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Song L, Cao F, Niu S, Xu M, Liang R, Ding K, Lin Z, Yao X, Liu D. Population Pharmacokinetic/Pharmacodynamic Analysis of the Glucokinase Activator PB201 in Healthy Volunteers and Patients with Type 2 Diabetes Mellitus: Facilitating the Clinical Development of PB201 in China. Clin Pharmacokinet 2024; 63:93-108. [PMID: 37985591 DOI: 10.1007/s40262-023-01321-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2023] [Indexed: 11/22/2023]
Abstract
PB201 is an orally active, partial glucokinase activator targeting both pancreatic and hepatic glucokinase. As the second glucokinase activator studied beyond phase I, PB201 has demonstrated promising glycemic effects as well as favorable pharmacokinetic (PK) and safety profiles in patients with type 2 diabetes mellitus (T2DM). This study aims to develop a population PK/pharmacodynamic (PD) model for PB201 using the pooled data from nine phase I/II clinical trials conducted in non-Chinese healthy volunteers and a T2DM population and to predict the PK/PD profile of PB201 in a Chinese T2DM population. We developed the PK/PD model using the non-linear mixed-effects modeling approach. All runs were performed using the first-order conditional estimation method with interaction. The pharmacokinetics of PB201 were well fitted by a one-compartment model with saturable absorption and linear elimination. The PD effects of PB201 on reducing the fasting plasma glucose and glycosylated hemoglobin levels in the T2DM population were described by indirect response models as stimulating the elimination of fasting plasma glucose, where the production of glycosylated hemoglobin was assumed to be stimulated by fasting plasma glucose. Covariate analyses revealed enhanced absorption of PB201 by food and decreased systemic clearance with ketoconazole co-administration, while no significant covariate was identified for the pharmacodynamics. The population PK model established for non-Chinese populations was shown to be applicable to the Chinese T2DM population as verified by the PK data from the Chinese phase I study. The final population PK/PD model predicted persistent and dose-dependent reductions in fasting plasma glucose and glycosylated hemoglobin levels in the Chinese T2DM population receiving 50/50 mg, 100/50 mg, and 100/100 mg PB201 twice daily for 24 weeks independent of co-administration of metformin. Overall, the proposed population PK/PD model quantitatively characterized the PK/PD properties of PB201 and the impact of covariates on its target populations, which allows the leveraging of extensive data in non-Chinese populations with the limited data in the Chinese T2DM population to successfully supported the waiver of the clinical phase II trial and facilitate the optimal dose regimen design of a pivotal phase III study of PB201 in China.
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Affiliation(s)
- Ling Song
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, 100191, China
- Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, 100191, China
| | - Fangrui Cao
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, 100191, China
| | - Shu Niu
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, 100191, China
| | - Michael Xu
- PegBio Co., Ltd., Suzhou, Jiangsu, China
| | | | - Ke Ding
- PegBio Co., Ltd., Suzhou, Jiangsu, China
| | | | - Xueting Yao
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, 100191, China.
| | - Dongyang Liu
- Drug Clinical Trial Center, Peking University Third Hospital, Beijing, 100191, China.
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, 100191, China.
- Beijing Key Laboratory of Cardiovascular Receptors Research, Peking University Third Hospital, Beijing, China.
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Paliwal A, Paliwal V, Jain S, Paliwal S, Sharma S. Current Insight on the Role of Glucokinase and Glucokinase Regulatory Protein in Diabetes. Mini Rev Med Chem 2024; 24:674-688. [PMID: 37612862 DOI: 10.2174/1389557523666230823151927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 06/19/2023] [Accepted: 07/13/2023] [Indexed: 08/25/2023]
Abstract
The glucokinase regulator (GCKR) gene encodes an inhibitor of the glucokinase enzyme (GCK), found only in hepatocytes and responsible for glucose metabolism. A common GCKR coding variation has been linked to various metabolic traits in genome-wide association studies. Rare GCKR polymorphisms influence GKRP activity, expression, and localization. Despite not being the cause, these variations are linked to hypertriglyceridemia. Because of their crystal structures, we now better understand the molecular interactions between GKRP and the GCK. Finally, small molecules that specifically bind to GKRP and decrease blood sugar levels in diabetic models have been identified. GCKR allelic spectrum changes affect lipid and glucose homeostasis. GKRP dysfunction has been linked to a variety of molecular causes, according to functional analysis. Numerous studies have shown that GKRP dysfunction is not the only cause of hypertriglyceridemia, implying that type 2 diabetes could be treated by activating liver-specific GCK via small molecule GKRP inhibition. The review emphasizes current discoveries concerning the characteristic roles of glucokinase and GKRP in hepatic glucose metabolism and diabetes. This information has influenced the growth of directed molecular therapies for diabetes, which has improved our understanding of lipid and glucose physiology.
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Affiliation(s)
- Ajita Paliwal
- Department of Pharmacy, Banasthali Vidyapith, Banasthali, Rajasthan, India
| | - Vartika Paliwal
- Department of Pharmacy, Banasthali Vidyapith, Banasthali, Rajasthan, India
| | - Smita Jain
- Department of Pharmacy, Banasthali Vidyapith, Banasthali, Rajasthan, India
| | - Sarvesh Paliwal
- Department of Pharmacy, Banasthali Vidyapith, Banasthali, Rajasthan, India
| | - Swapnil Sharma
- Department of Pharmacy, Banasthali Vidyapith, Banasthali, Rajasthan, India
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3
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Wang Y, Regeenes R, Memon M, Rocheleau JV. Insulin C-peptide secretion on-a-chip to measure the dynamics of secretion and metabolism from individual islets. CELL REPORTS METHODS 2023; 3:100602. [PMID: 37820726 PMCID: PMC10626205 DOI: 10.1016/j.crmeth.2023.100602] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 08/16/2023] [Accepted: 09/15/2023] [Indexed: 10/13/2023]
Abstract
First-phase glucose-stimulated insulin secretion is mechanistically linked to type 2 diabetes, yet the underlying metabolism is difficult to discern due to significant islet-to-islet variability. Here, we miniaturize a fluorescence anisotropy immunoassay onto a microfluidic device to measure C-peptide secretion from individual islets as a surrogate for insulin (InsC-chip). This method measures secretion from up to four islets at a time with ∼7 s resolution while providing an optical window for real-time live-cell imaging. Using the InsC-chip, we reveal two glucose-dependent peaks of insulin secretion (i.e., a double peak) within the classically defined 1st phase (<10 min). By combining real-time secretion and live-cell imaging, we show islets transition from glycolytic to oxidative phosphorylation (OxPhos)-driven metabolism at the nadir of the peaks. Overall, these data validate the InsC-chip to measure glucose-stimulated insulin secretion while revealing new dynamics in secretion defined by a shift in glucose metabolism.
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Affiliation(s)
- Yufeng Wang
- Advanced Diagnostics, Toronto General Hospital Research Institute, Toronto, ON M5G 1L7, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Romario Regeenes
- Advanced Diagnostics, Toronto General Hospital Research Institute, Toronto, ON M5G 1L7, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Mahnoor Memon
- Advanced Diagnostics, Toronto General Hospital Research Institute, Toronto, ON M5G 1L7, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Jonathan V Rocheleau
- Advanced Diagnostics, Toronto General Hospital Research Institute, Toronto, ON M5G 1L7, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada; Departments of Medicine and Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Zhang M, Lei Z, Yu Z, Yao X, Li H, Xu M, Liu D. Development of a PBPK model to quantitatively understand absorption and disposition mechanism and support future clinical trials for PB-201. CPT Pharmacometrics Syst Pharmacol 2023; 12:941-952. [PMID: 37078371 PMCID: PMC10349193 DOI: 10.1002/psp4.12964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 03/11/2023] [Accepted: 03/18/2023] [Indexed: 04/21/2023] Open
Abstract
PB-201 is the second glucokinase activator in the world to enter the phase III clinical trials for the treatment of type 2 diabetes mellitus (T2DM). Combined with the efficacy advantages and the friendly absorption, distribution, metabolism, and excretion characteristics, the indication population of PB-201 will be broad. Because the liver is the primary organ for PB-201 elimination, and the elderly account for 20% of patients with T2DM, it is essential to estimate PB-201 exposure in specific populations to understand the pharmacokinetic characteristics and avoid hypoglycemia. Despite the limited contribution of CYP3A4 to PB-201 metabolism in vivo, the dual effects of nonspecific inhibitors/inducers on PB-201 (substrate for CYP3A4 and CYP2C9 isoenzymes) exposure under fasted and fed states also need to be evaluated to understand potential risks of combination therapy. To grasp the unknown information, the physiologically-based pharmacokinetic (PBPK) model was first developed and the influence of internal and external factors on PB-201 exposure was evaluated. Results are shown that the predictive performance of the mechanistic PBPK model meets the predefined criteria, and can accurately capture the absorption and disposition characteristics. Impaired liver function and age-induced changes in physiological factors may significantly increase the exposure under fasted state by 36%-158% and 48%-82%, respectively. The nonspecific inhibitor (fluconazole) and inducer (rifampicin) may separately increase/decrease PB-201 systemic exposure by 44% and 58% under fasted state, and by 78% and 47% under fed state. Therefore, the influence of internal and external factors on PB-201 exposure deserves attention, and the precision dose can be informed in future clinical studies based on the predicted results.
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Affiliation(s)
- Miao Zhang
- Drug Clinical Trial CenterPeking University Third HospitalBeijingChina
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical SciencesUniversity at Buffalo, The State University of New YorkBuffaloNew YorkUSA
| | - Zihan Lei
- Drug Clinical Trial CenterPeking University Third HospitalBeijingChina
| | - Ziheng Yu
- Drug Clinical Trial CenterPeking University Third HospitalBeijingChina
- Department of Obstetrics and GynecologyPeking University Third HospitalBeijingChina
| | - Xueting Yao
- Drug Clinical Trial CenterPeking University Third HospitalBeijingChina
| | - Haiyan Li
- Drug Clinical Trial CenterPeking University Third HospitalBeijingChina
- Department of Cardiology and Institute of Vascular MedicinePeking University Third HospitalBeijingChina
| | - Min Xu
- PegBio Co., Ltd.SuzhouJiangsuChina
| | - Dongyang Liu
- Drug Clinical Trial CenterPeking University Third HospitalBeijingChina
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Tariq M, de Souza AH, Bensellam M, Chae H, Jaffredo M, Close AF, Deglasse JP, Santos LRB, Buemi A, Mourad NI, Wojtusciszyn A, Raoux M, Gilon P, Broca C, Jonas JC. Prolonged culture of human pancreatic islets under glucotoxic conditions changes their acute beta cell calcium and insulin secretion glucose response curves from sigmoid to bell-shaped. Diabetologia 2023; 66:709-723. [PMID: 36459178 DOI: 10.1007/s00125-022-05842-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 10/18/2022] [Indexed: 12/04/2022]
Abstract
AIMS/HYPOTHESIS The rapid remission of type 2 diabetes by a diet very low in energy correlates with a marked improvement in glucose-stimulated insulin secretion (GSIS), emphasising the role of beta cell dysfunction in the early stages of the disease. In search of novel mechanisms of beta cell dysfunction after long-term exposure to mild to severe glucotoxic conditions, we extensively characterised the alterations in insulin secretion and upstream coupling events in human islets cultured for 1-3 weeks at ~5, 8, 10 or 20 mmol/l glucose and subsequently stimulated by an acute stepwise increase in glucose concentration. METHODS Human islets from 49 non-diabetic donors (ND-islets) and six type 2 diabetic donors (T2D-islets) were obtained from five isolation centres. After shipment, the islets were precultured for 3-7 days in RPMI medium containing ~5 mmol/l glucose and 10% (vol/vol) heat-inactivated FBS with selective islet picking at each medium renewal. Islets were then cultured for 1-3 weeks in RPMI containing ~5, 8, 10 or 20 mmol/l glucose before measurement of insulin secretion during culture, islet insulin and DNA content, beta cell apoptosis and cytosolic and mitochondrial glutathione redox state, and assessment of dynamic insulin secretion and upstream coupling events during acute stepwise stimulation with glucose [NAD(P)H autofluorescence, ATP/(ATP+ADP) ratio, electrical activity, cytosolic Ca2+ concentration ([Ca2+]c)]. RESULTS Culture of ND-islets for 1-3 weeks at 8, 10 or 20 vs 5 mmol/l glucose did not significantly increase beta cell apoptosis or oxidative stress but decreased insulin content in a concentration-dependent manner and increased beta cell sensitivity to subsequent acute stimulation with glucose. Islet glucose responsiveness was higher after culture at 8 or 10 vs 5 mmol/l glucose and markedly reduced after culture at 20 vs 5 mmol/l glucose. In addition, the [Ca2+]c and insulin secretion responses to acute stepwise stimulation with glucose were no longer sigmoid but bell-shaped, with maximal stimulation at 5 or 10 mmol/l glucose and rapid sustained inhibition above that concentration. Such paradoxical inhibition was, however, no longer observed when islets were acutely depolarised by 30 mmol/l extracellular K+. The glucotoxic alterations of beta cell function were fully reversible after culture at 5 mmol/l glucose and were mimicked by pharmacological activation of glucokinase during culture at 5 mmol/l glucose. Similar results to those seen in ND-islets were obtained in T2D-islets, except that their rate of insulin secretion during culture at 8 and 20 mmol/l glucose was lower, their cytosolic glutathione oxidation increased after culture at 8 and 20 mmol/l glucose, and the alterations in GSIS and upstream coupling events were greater after culture at 8 mmol/l glucose. CONCLUSIONS/INTERPRETATION Prolonged culture of human islets under moderate to severe glucotoxic conditions markedly increased their glucose sensitivity and revealed a bell-shaped acute glucose response curve for changes in [Ca2+]c and insulin secretion, with maximal stimulation at 5 or 10 mmol/l glucose and rapid inhibition above that concentration. This novel glucotoxic alteration may contribute to beta cell dysfunction in type 2 diabetes independently from a detectable increase in beta cell apoptosis.
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Affiliation(s)
- Mohammad Tariq
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
- Lund University Diabetes Centre, Department of Clinical Sciences, Lund University, Malmö, Sweden
| | - Arnaldo H de Souza
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Mohammed Bensellam
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Heeyoung Chae
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Manon Jaffredo
- CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, University of Bordeaux, Pessac, France
| | - Anne-Françoise Close
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Jean-Philippe Deglasse
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Laila R B Santos
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
- Bio Base Europe Pilot Plant (BBEPP), Ghent, Belgium
| | - Antoine Buemi
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle de chirurgie expérimentale, Université catholique de Louvain, Brussels, Belgium
| | - Nizar I Mourad
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle de chirurgie expérimentale, Université catholique de Louvain, Brussels, Belgium
| | - Anne Wojtusciszyn
- Laboratoire de Thérapie Cellulaire du Diabète, Institut de Médecine Régénérative et Biothérapies, Hôpital St Eloi, CHU Montpellier, Montpellier, France
- Service d'Endocrinologie, Diabétologie et Métabolisme, Centre Hospitalier Universitaire Vaudois and Université de Lausanne, Lausanne, Switzerland
| | - Matthieu Raoux
- CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, University of Bordeaux, Pessac, France
| | - Patrick Gilon
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium
| | - Christophe Broca
- Laboratoire de Thérapie Cellulaire du Diabète, Institut de Médecine Régénérative et Biothérapies, Hôpital St Eloi, CHU Montpellier, Montpellier, France
| | - Jean-Christophe Jonas
- Secteur des sciences de la santé, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Université catholique de Louvain, Brussels, Belgium.
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Liu J, Fu H, Kang F, Ning G, Ni Q, Wang W, Wang Q. β-Cell glucokinase expression was increased in type 2 diabetes subjects with better glycemic control. J Diabetes 2023; 15:409-418. [PMID: 36942376 PMCID: PMC10172022 DOI: 10.1111/1753-0407.13380] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 02/22/2023] [Accepted: 02/26/2023] [Indexed: 03/23/2023] Open
Abstract
BACKGROUND Type 2 diabetes (T2D) is characterized by a progressive deterioration of β-cell function with a continuous decline in insulin secretion. Glucokinase (GCK) facilitates the rate-limiting step of glycolysis in pancreatic β-cells, to acquire the proper glucose-stimulated insulin secretion. Multiple glucokinase activators (GKAs) have been developed and clinically tested. However, the dynamic change of human pancreatic GCK expression during T2D progression has not been investigated. METHODS We evaluated GCK expression by measuring the average immunoreactivity of GCK in insulin+ or glucagon+ cells from pancreatic sections of 11 nondiabetic subjects (ND), 10 subjects with impaired fasting glucose (IFG), 9 with well-controlled T2D (wT2D), and 5 individuals with poorly controlled T2D (uT2D). We also assessed the relationship between GCK expression and adaptive unfolded protein response (UPR) in human diabetic β-cells. RESULTS We did not detect changes of GCK expression in IFG islets. However, we found β-cell GCK levels were significantly increased in T2D with adequate glucose control (wT2D) but not in T2D with poor glucose control (uT2D). Furthermore, there was a strong positive correlation between GCK expression and adaptive UPR (spliced X-box binding protein 1 [XBP1s] and activating transcription factor 4 [ATF4]), as well as functional maturity marker (urocortin-3 [UCN3]) in human diabetic β-cells. CONCLUSIONS Our study demonstrates that inductions of GCK enhanced adaptive UPR and UCN3 in human β-cells, which might be an adaptive mechanism during T2D progression. This finding provides a rationale for exploring novel molecules that activate β-cell GCK and thereby improve pharmacological treatment of T2D.
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Affiliation(s)
- Jingwen Liu
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hui Fu
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fuyun Kang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guang Ning
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Sino-French Research Center for Life Sciences and Genomics Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qicheng Ni
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weiqing Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qidi Wang
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai National Clinical Research Center for Metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR China, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Sino-French Research Center for Life Sciences and Genomics Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Chen KH, Doliba N, May CL, Roman J, Ustione A, Tembo T, Negron A, Radovick S, Piston DW, Glaser B, Kaestner KH, Matschinsky FM. Genetic activation of glucokinase in a minority of pancreatic beta cells causes hypoglycemia in mice. Life Sci 2022; 309:120952. [PMID: 36100080 PMCID: PMC10312065 DOI: 10.1016/j.lfs.2022.120952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 09/06/2022] [Accepted: 09/08/2022] [Indexed: 01/05/2023]
Abstract
AIMS Glucokinase (GK) is expressed in the glucose-sensing cells of the islets of Langerhans and plays a critical role in glucose homeostasis. Here, we tested the hypothesis that genetic activation of GK in a small subset of β-cells is sufficient to change the glucose set-point of the whole islet. MATERIAL AND METHODS Mouse models of cell-type specific GK deficiency (GKKO) and genetic enzyme activation (GKKI) in a subset of β-cells were obtained by crossing the αGSU (gonadotropin alpha subunit)-Cre transgene with the appropriate GK mutant alleles. Metabolic analyses consisted of glucose tolerance tests, perifusion of isolated islets and intracellular calcium measurements. KEY FINDINGS The αGSU-Cre transgene produced genetically mosaic islets, as Cre was active in 15 ± 1.2 % of β-cells. While mice deficient for GK in a subset of islet cells were normal, unexpectedly, GKKI mice were chronically hypoglycemic, glucose intolerant, and had a lower threshold for glucose stimulated insulin secretion. GKKI mice exhibited an average fasting blood glucose level of 3.5 mM. GKKI islets responded with intracellular calcium signals that spread through the whole islets at 1 mM and secreted insulin at 3 mM glucose. SIGNIFICANCE Genetic activation of GK in a minority of β-cells is sufficient to change the glucose threshold for insulin secretion in the entire islet and thereby glucose homeostasis in the whole animal. These data support the model in which β-cells with higher GK activity function as 'hub' or 'trigger' cells and thus control insulin secretion by the β-cell collective within the islet.
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Affiliation(s)
- Kevin H Chen
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Nicolai Doliba
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Catherine L May
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Jeffrey Roman
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Alessandro Ustione
- Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Teguru Tembo
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA
| | - Ariel Negron
- Department of Medicine and Pediatrics, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA
| | - Sally Radovick
- Department of Medicine and Pediatrics, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ 08901, USA
| | - David W Piston
- Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Benjamin Glaser
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA.
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA 19014, USA.
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8
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Ježek P, Holendová B, Jabůrek M, Dlasková A, Plecitá-Hlavatá L. Contribution of Mitochondria to Insulin Secretion by Various Secretagogues. Antioxid Redox Signal 2022; 36:920-952. [PMID: 34180254 PMCID: PMC9125579 DOI: 10.1089/ars.2021.0113] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Significance: Mitochondria determine glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells by elevating ATP synthesis. As the metabolic and redox hub, mitochondria provide numerous links to the plasma membrane channels, insulin granule vesicles (IGVs), cell redox, NADH, NADPH, and Ca2+ homeostasis, all affecting insulin secretion. Recent Advances: Mitochondrial redox signaling was implicated in several modes of insulin secretion (branched-chain ketoacid [BCKA]-, fatty acid [FA]-stimulated). Mitochondrial Ca2+ influx was found to enhance GSIS, reflecting cytosolic Ca2+ oscillations induced by action potential spikes (intermittent opening of voltage-dependent Ca2+ and K+ channels) or the superimposed Ca2+ release from the endoplasmic reticulum (ER). The ATPase inhibitory factor 1 (IF1) was reported to tune the glucose sensitivity range for GSIS. Mitochondrial protein kinase A was implicated in preventing the IF1-mediated inhibition of the ATP synthase. Critical Issues: It is unknown how the redox signal spreads up to the plasma membrane and what its targets are, what the differences in metabolic, redox, NADH/NADPH, and Ca2+ signaling, and homeostasis are between the first and second GSIS phase, and whether mitochondria can replace ER in the amplification of IGV exocytosis. Future Directions: Metabolomics studies performed to distinguish between the mitochondrial matrix and cytosolic metabolites will elucidate further details. Identifying the targets of cell signaling into mitochondria and of mitochondrial retrograde metabolic and redox signals to the cell will uncover further molecular mechanisms for insulin secretion stimulated by glucose, BCKAs, and FAs, and the amplification of secretion by glucagon-like peptide (GLP-1) and metabotropic receptors. They will identify the distinction between the hub β-cells and their followers in intact and diabetic states. Antioxid. Redox Signal. 36, 920-952.
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Affiliation(s)
- Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Blanka Holendová
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Andrea Dlasková
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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9
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Affiliation(s)
- Gaowei Wang
- Department of Pediatrics, Pediatric Diabetes Research Center, University of California San Diego, La Jolla, CA, USA
| | - Maike Sander
- Department of Pediatrics, Pediatric Diabetes Research Center, University of California San Diego, La Jolla, CA, USA.
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10
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Weir GC, Butler PC, Bonner-Weir S. The β-cell glucose toxicity hypothesis: Attractive but difficult to prove. Metabolism 2021; 124:154870. [PMID: 34480921 PMCID: PMC8530963 DOI: 10.1016/j.metabol.2021.154870] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/11/2021] [Accepted: 08/25/2021] [Indexed: 12/16/2022]
Abstract
β cells in the hyperglycemic environment of diabetes have marked changes in phenotype and function that are largely reversible if glucose levels can be returned to normal. A leading hypothesis is that these changes are caused by the elevated glucose levels leading to the concept of glucose toxicity. Support for the glucose toxicity hypothesis is largely circumstantial, but little progress has been made in defining the responsible mechanisms. Then questions emerge that are difficult to answer. In the very earliest stages of diabetes development, there is a dramatic loss of glucose-induced first-phase insulin release (FPIR) with only trivial elevations of blood glucose levels. A related question is how impaired insulin action on target tissues such as liver, muscle and fat can cause increased insulin secretion. The existence of a sophisticated feedback mechanism between insulin secretion and insulin action on peripheral tissues driven by glucose has been postulated, but it has been difficult to measure increases in blood glucose levels that might have been expected. These complexities force us to challenge the simplicity of the glucose toxicity hypothesis and feedback mechanisms. It may turn out that glucose is somehow driving all of these changes, but we must develop new questions and experimental approaches to test the hypothesis.
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Affiliation(s)
- Gordon C Weir
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA, USA.
| | - Peter C Butler
- Larry l. Hillblom Islet Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Susan Bonner-Weir
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA, USA
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11
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Langlhofer G, Kogel A, Schaefer M. Glucose-induced [Ca2+]i oscillations in β cells are composed of trains of spikes within a subplasmalemmal microdomain. Cell Calcium 2021; 99:102469. [PMID: 34509871 DOI: 10.1016/j.ceca.2021.102469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 10/20/2022]
Abstract
Electrical activity and oscillations of cytosolic Ca2+ concentrations ([Ca2+]i) that trigger insulin release in response to glucose are key functions of pancreatic β cells. Although oscillatory Ca2+ signals have been intensively studied in β cells, their lower frequency did not match that of electrical activity. In addition, the measured peak [Ca2+]i did not reach levels that are typically required by synaptotagmins to elicit the release of insulin-containing vesicles in live-cell experiments. We therefore sought to resolve the Ca2+ dynamics in the subplasmalemmal microdomain that is critical for triggering fast exocytosis. Applying total internal reflection fluorescence (TIRF) microscopy in insulin-producing INS-1E and primary mouse β cells, we resolved extraordinary fast trains of Ca2+ spiking (frequency > 3 s-1) in response to glucose exposure. Using a low-affinity [Ca2+]i indicator dye, we provide experimental evidence that Ca2+ spikes reach low micromolar apparent concentrations in the vicinity of the plasma membrane. Analysis of Ca2+ spikes evoked by repeated depolarization for 10 ms closely matched the Ca2+ dynamics observed upon glucose application. To our knowledge, this is the first study that experimentally demonstrates Ca2+ spikes in β cells with velocities that resemble those of bursting or continuously appearing trains of action potentials (APs) in non-patched cells.
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Affiliation(s)
- Georg Langlhofer
- Rudolf-Boehm-Institute for Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany
| | - Alexander Kogel
- Rudolf-Boehm-Institute for Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany
| | - Michael Schaefer
- Rudolf-Boehm-Institute for Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.
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12
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Tuluc P, Theiner T, Jacobo-Piqueras N, Geisler SM. Role of High Voltage-Gated Ca 2+ Channel Subunits in Pancreatic β-Cell Insulin Release. From Structure to Function. Cells 2021; 10:2004. [PMID: 34440773 PMCID: PMC8393260 DOI: 10.3390/cells10082004] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/03/2021] [Indexed: 02/07/2023] Open
Abstract
The pancreatic islets of Langerhans secrete several hormones critical for glucose homeostasis. The β-cells, the major cellular component of the pancreatic islets, secrete insulin, the only hormone capable of lowering the plasma glucose concentration. The counter-regulatory hormone glucagon is secreted by the α-cells while δ-cells secrete somatostatin that via paracrine mechanisms regulates the α- and β-cell activity. These three peptide hormones are packed into secretory granules that are released through exocytosis following a local increase in intracellular Ca2+ concentration. The high voltage-gated Ca2+ channels (HVCCs) occupy a central role in pancreatic hormone release both as a source of Ca2+ required for excitation-secretion coupling as well as a scaffold for the release machinery. HVCCs are multi-protein complexes composed of the main pore-forming transmembrane α1 and the auxiliary intracellular β, extracellular α2δ, and transmembrane γ subunits. Here, we review the current understanding regarding the role of all HVCC subunits expressed in pancreatic β-cell on electrical activity, excitation-secretion coupling, and β-cell mass. The evidence we review was obtained from many seminal studies employing pharmacological approaches as well as genetically modified mouse models. The significance for diabetes in humans is discussed in the context of genetic variations in the genes encoding for the HVCC subunits.
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Affiliation(s)
- Petronel Tuluc
- Centre for Molecular Biosciences, Department of Pharmacology and Toxicology, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; (T.T.); (N.J.-P.); (S.M.G.)
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13
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Rahman MS, Hossain KS, Das S, Kundu S, Adegoke EO, Rahman MA, Hannan MA, Uddin MJ, Pang MG. Role of Insulin in Health and Disease: An Update. Int J Mol Sci 2021; 22:6403. [PMID: 34203830 PMCID: PMC8232639 DOI: 10.3390/ijms22126403] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/12/2021] [Accepted: 06/14/2021] [Indexed: 02/06/2023] Open
Abstract
Insulin is a polypeptide hormone mainly secreted by β cells in the islets of Langerhans of the pancreas. The hormone potentially coordinates with glucagon to modulate blood glucose levels; insulin acts via an anabolic pathway, while glucagon performs catabolic functions. Insulin regulates glucose levels in the bloodstream and induces glucose storage in the liver, muscles, and adipose tissue, resulting in overall weight gain. The modulation of a wide range of physiological processes by insulin makes its synthesis and levels critical in the onset and progression of several chronic diseases. Although clinical and basic research has made significant progress in understanding the role of insulin in several pathophysiological processes, many aspects of these functions have yet to be elucidated. This review provides an update on insulin secretion and regulation, and its physiological roles and functions in different organs and cells, and implications to overall health. We cast light on recent advances in insulin-signaling targeted therapies, the protective effects of insulin signaling activators against disease, and recommendations and directions for future research.
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Affiliation(s)
- Md Saidur Rahman
- Department of Animal Science & Technology and BET Research Institute, Chung-Ang University, Anseong 17546, Korea; (M.S.R.); (E.O.A.)
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Khandkar Shaharina Hossain
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Sharnali Das
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Sushmita Kundu
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
| | - Elikanah Olusayo Adegoke
- Department of Animal Science & Technology and BET Research Institute, Chung-Ang University, Anseong 17546, Korea; (M.S.R.); (E.O.A.)
| | - Md. Ataur Rahman
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
- Department of Pathology, College of Korean Medicine, Kyung Hee University, Seoul 02447, Korea
| | - Md. Abdul Hannan
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
- Department of Biochemistry and Molecular Biology, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh
| | - Md Jamal Uddin
- ABEx Bio-Research Center, East Azampur, Dhaka 1230, Bangladesh; (K.S.H.); (S.D.); (S.K.); (M.A.R.); (M.A.H.); (M.J.U.)
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Woman’s University, Seoul 03760, Korea
| | - Myung-Geol Pang
- Department of Animal Science & Technology and BET Research Institute, Chung-Ang University, Anseong 17546, Korea; (M.S.R.); (E.O.A.)
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Veluthakal R, Thurmond DC. Emerging Roles of Small GTPases in Islet β-Cell Function. Cells 2021; 10:1503. [PMID: 34203728 PMCID: PMC8232272 DOI: 10.3390/cells10061503] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/08/2021] [Accepted: 06/08/2021] [Indexed: 12/16/2022] Open
Abstract
Several small guanosine triphosphatases (GTPases) from the Ras protein superfamily regulate glucose-stimulated insulin secretion in the pancreatic islet β-cell. The Rho family GTPases Cdc42 and Rac1 are primarily involved in relaying key signals in several cellular functions, including vesicle trafficking, plasma membrane homeostasis, and cytoskeletal dynamics. They orchestrate specific changes at each spatiotemporal region within the β-cell by coordinating with signal transducers, guanine nucleotide exchange factors (GEFs), GTPase-activating factors (GAPs), and their effectors. The Arf family of small GTPases is involved in vesicular trafficking (exocytosis and endocytosis) and actin cytoskeletal dynamics. Rab-GTPases regulate pre-exocytotic and late endocytic membrane trafficking events in β-cells. Several additional functions for small GTPases include regulating transcription factor activity and mitochondrial dynamics. Importantly, defects in several of these GTPases have been found associated with type 2 diabetes (T2D) etiology. The purpose of this review is to systematically denote the identities and molecular mechanistic steps in the glucose-stimulated insulin secretion pathway that leads to the normal release of insulin. We will also note newly identified defects in these GTPases and their corresponding regulatory factors (e.g., GDP dissociation inhibitors (GDIs), GEFs, and GAPs) in the pancreatic β-cells, which contribute to the dysregulation of metabolism and the development of T2D.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
| | - Debbie C. Thurmond
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
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15
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Henquin JC. Glucose-induced insulin secretion in isolated human islets: Does it truly reflect β-cell function in vivo? Mol Metab 2021; 48:101212. [PMID: 33737253 PMCID: PMC8065218 DOI: 10.1016/j.molmet.2021.101212] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Diabetes always involves variable degrees of β-cell demise and malfunction leading to insufficient insulin secretion. Besides clinical investigations, many research projects used rodent islets to study various facets of β-cell pathophysiology. Their important contributions laid the foundations of steadily increasing numbers of experimental studies resorting to isolated human islets. SCOPE OF REVIEW This review, based on an analysis of data published over 60 years of clinical investigations and results of more recent studies in isolated islets, addresses a question of translational nature. Does the information obtained in vitro with human islets fit with our knowledge of insulin secretion in man? The aims are not to discuss specificities of pathways controlling secretion but to compare qualitative and quantitative features of glucose-induced insulin secretion in isolated human islets and in living human subjects. MAJOR CONCLUSIONS Much of the information gathered in vitro can reliably be translated to the in vivo situation. There is a fairly good, though not complete, qualitative and quantitative coherence between insulin secretion rates measured in vivo and in vitro during stimulation with physiological glucose concentrations, but the concordance fades out under extreme conditions. Perplexing discrepancies also exist between insulin secretion in subjects with Type 2 diabetes and their islets studied in vitro, in particular concerning the kinetics. Future projects should ascertain that the experimental conditions are close to physiological and do not alter the function of normal and diabetic islets.
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Affiliation(s)
- Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium.
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16
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Gil-Rivera M, Medina-Gali RM, Martínez-Pinna J, Soriano S. Physiology of pancreatic β-cells: Ion channels and molecular mechanisms implicated in stimulus-secretion coupling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 359:287-323. [PMID: 33832651 DOI: 10.1016/bs.ircmb.2021.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The human and mouse islet of Langerhans is an endocrine organ composed of five different cells types; insulin-secreting β-cells, glucagon-producing α-cells, somatostatin-producing δ-cells, pancreatic polypeptide-secreting PP cells and ɛ-cells that secretes ghrelin. The most important cells are the pancreatic β-cells that comprise around 45-50% of human islets and 75-80% in the mouse. Pancreatic β-cells secrete insulin at high glucose concentration, thereby finely regulating glycaemia by the hypoglycaemic effects of this hormone. Different ion channels are implicated in the stimulus-secretion coupling of insulin. An increase in the intracellular ATP concentration leads to closure KATP channels, depolarizing the cell and opening voltage-gated calcium channels. The increase of intracellular calcium concentration induced by calcium entry through voltage-gated calcium channels promotes insulin secretion. Here, we briefly describe the diversity of ion channels present in pancreatic β-cells and the different mechanisms that are responsible to induce insulin secretion in human and mouse cells. Moreover, we described the pathophysiology due to alterations in the physiology of the main ion channels present in pancreatic β-cell and its implication to predispose metabolic disorders as type 2 diabetes mellitus.
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Affiliation(s)
- Minerva Gil-Rivera
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain.
| | - Regla M Medina-Gali
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, Elche, Spain
| | - Juan Martínez-Pinna
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, Elche, Spain
| | - Sergi Soriano
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain; Instituto de Investigación, Desarrollo e Innovación en Biotecnología Sanitaria de Elche (IDiBE), Universidad Miguel Hernández, Elche, Spain.
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17
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Grubelnik V, Zmazek J, Markovič R, Gosak M, Marhl M. Mitochondrial Dysfunction in Pancreatic Alpha and Beta Cells Associated with Type 2 Diabetes Mellitus. Life (Basel) 2020; 10:E348. [PMID: 33327428 PMCID: PMC7764865 DOI: 10.3390/life10120348] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/04/2020] [Accepted: 12/10/2020] [Indexed: 12/16/2022] Open
Abstract
Type 2 diabetes mellitus is a complex multifactorial disease of epidemic proportions. It involves genetic and lifestyle factors that lead to dysregulations in hormone secretion and metabolic homeostasis. Accumulating evidence indicates that altered mitochondrial structure, function, and particularly bioenergetics of cells in different tissues have a central role in the pathogenesis of type 2 diabetes mellitus. In the present study, we explore how mitochondrial dysfunction impairs the coupling between metabolism and exocytosis in the pancreatic alpha and beta cells. We demonstrate that reduced mitochondrial ATP production is linked with the observed defects in insulin and glucagon secretion by utilizing computational modeling approach. Specifically, a 30-40% reduction in alpha cells' mitochondrial function leads to a pathological shift of glucagon secretion, characterized by oversecretion at high glucose concentrations and insufficient secretion in hypoglycemia. In beta cells, the impaired mitochondrial energy metabolism is accompanied by reduced insulin secretion at all glucose levels, but the differences, compared to a normal beta cell, are the most pronounced in hyperglycemia. These findings improve our understanding of metabolic pathways and mitochondrial bioenergetics in the pathology of type 2 diabetes mellitus and might help drive the development of innovative therapies to treat various metabolic diseases.
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Affiliation(s)
- Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; (V.G.); (R.M.)
| | - Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
| | - Rene Markovič
- Faculty of Electrical Engineering and Computer Science, University of Maribor, SI-2000 Maribor, Slovenia; (V.G.); (R.M.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
| | - Marko Gosak
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
- Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia; (J.Z.); (M.G.)
- Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia
- Faculty of Education, University of Maribor, SI-2000 Maribor, Slovenia
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18
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Moede T, Leibiger B, Vaca Sanchez P, Daré E, Köhler M, Muhandiramlage TP, Leibiger IB, Berggren PO. Glucokinase intrinsically regulates glucose sensing and glucagon secretion in pancreatic alpha cells. Sci Rep 2020; 10:20145. [PMID: 33214580 PMCID: PMC7678872 DOI: 10.1038/s41598-020-76863-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/02/2020] [Indexed: 01/08/2023] Open
Abstract
The secretion of glucagon by pancreatic alpha cells is regulated by a number of external and intrinsic factors. While the electrophysiological processes linking a lowering of glucose concentrations to an increased glucagon release are well characterized, the evidence for the identity and function of the glucose sensor is still incomplete. In the present study we aimed to address two unsolved problems: (1) do individual alpha cells have the intrinsic capability to regulate glucagon secretion by glucose, and (2) is glucokinase the alpha cell glucose sensor in this scenario. Single cell RT-PCR was used to confirm that glucokinase is the main glucose-phosphorylating enzyme expressed in rat pancreatic alpha cells. Modulation of glucokinase activity by pharmacological activators and inhibitors led to a lowering or an increase of the glucose threshold of glucagon release from single alpha cells, measured by TIRF microscopy, respectively. Knockdown of glucokinase expression resulted in a loss of glucose control of glucagon secretion. Taken together this study provides evidence for a crucial role of glucokinase in intrinsic glucose regulation of glucagon release in rat alpha cells.
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Affiliation(s)
- Tilo Moede
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden.
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden
| | - Pilar Vaca Sanchez
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden
| | - Elisabetta Daré
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden
| | - Martin Köhler
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden
| | - Thusitha P Muhandiramlage
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden
| | - Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska Sjukhuset L1:03, 17176, Stockholm, Sweden
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19
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Amouyal C, Castel J, Guay C, Lacombe A, Denom J, Migrenne-Li S, Rouault C, Marquet F, Georgiadou E, Stylianides T, Luquet S, Le Stunff H, Scharfmann R, Clément K, Rutter GA, Taboureau O, Magnan C, Regazzi R, Andreelli F. A surrogate of Roux-en-Y gastric bypass (the enterogastro anastomosis surgery) regulates multiple beta-cell pathways during resolution of diabetes in ob/ob mice. EBioMedicine 2020; 58:102895. [PMID: 32739864 PMCID: PMC7393530 DOI: 10.1016/j.ebiom.2020.102895] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Bariatric surgery is an effective treatment for type 2 diabetes. Early post-surgical enhancement of insulin secretion is key for diabetes remission. The full complement of mechanisms responsible for improved pancreatic beta cell functionality after bariatric surgery is still unclear. Our aim was to identify pathways, evident in the islet transcriptome, that characterize the adaptive response to bariatric surgery independently of body weight changes. METHODS We performed entero-gastro-anastomosis (EGA) with pyloric ligature in leptin-deficient ob/ob mice as a surrogate of Roux-en-Y gastric bypass (RYGB) in humans. Multiple approaches such as determination of glucose tolerance, GLP-1 and insulin secretion, whole body insulin sensitivity, ex vivo glucose-stimulated insulin secretion (GSIS) and functional multicellular Ca2+-imaging, profiling of mRNA and of miRNA expression were utilized to identify significant biological processes involved in pancreatic islet recovery. FINDINGS EGA resolved diabetes, increased pancreatic insulin content and GSIS despite a persistent increase in fat mass, systemic and intra-islet inflammation, and lipotoxicity. Surgery differentially regulated 193 genes in the islet, most of which were involved in the regulation of glucose metabolism, insulin secretion, calcium signaling or beta cell viability, and these were normalized alongside changes in glucose metabolism, intracellular Ca2+ dynamics and the threshold for GSIS. Furthermore, 27 islet miRNAs were differentially regulated, four of them hubs in a miRNA-gene interaction network and four others part of a blood signature of diabetes resolution in ob/ob mice and in humans. INTERPRETATION Taken together, our data highlight novel miRNA-gene interactions in the pancreatic islet during the resolution of diabetes after bariatric surgery that form part of a blood signature of diabetes reversal. FUNDING European Union's Horizon 2020 research and innovation programme via the Innovative Medicines Initiative 2 Joint Undertaking (RHAPSODY), INSERM, Société Francophone du Diabète, Institut Benjamin Delessert, Wellcome Trust Investigator Award (212625/Z/18/Z), MRC Programme grants (MR/R022259/1, MR/J0003042/1, MR/L020149/1), Diabetes UK (BDA/11/0004210, BDA/15/0005275, BDA 16/0005485) project grants, National Science Foundation (310030-188447), Fondation de l'Avenir.
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Affiliation(s)
- Chloé Amouyal
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France; AP-HP, Pitié-Salpêtrière Hospital, Diabetology department, F-75013 Paris, France
| | - Julien Castel
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Claudiane Guay
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| | - Amélie Lacombe
- PreclinICAN, Institute of Cardiometabolism and Nutrition, Paris, France
| | - Jessica Denom
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | | | - Christine Rouault
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France
| | - Florian Marquet
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France
| | - Eleni Georgiadou
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | | | - Serge Luquet
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Hervé Le Stunff
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Raphael Scharfmann
- Université de Paris, Cochin Institute, Inserm U1016, Paris 75014, France
| | - Karine Clément
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France; APHP, Pitié-Salpêtrière Hospital, Nutrition department, F-75013 Paris, France
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK; Lee Kong Chian School of Medicine, Nan Yang Technological University, Singapore
| | - Olivier Taboureau
- Université de Paris, BFA, Team CMPLI, Inserm U1133, CNRS UMR 8251, Paris, France
| | | | - Romano Regazzi
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland; Department of Biomedical Sciences, University of Lausanne, Rue du Bugnon 7, CH-1005 Lausanne, Switzerland
| | - Fabrizio Andreelli
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France; AP-HP, Pitié-Salpêtrière Hospital, Diabetology department, F-75013 Paris, France.
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20
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Las G, Oliveira MF, Shirihai OS. Emerging roles of β-cell mitochondria in type-2-diabetes. Mol Aspects Med 2020; 71:100843. [PMID: 31918997 DOI: 10.1016/j.mam.2019.100843] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/23/2019] [Accepted: 12/27/2019] [Indexed: 10/25/2022]
Abstract
Type-2-Diabetes (T2D) is the most common metabolic disease in the world today. It erupts as a result of peripheral insulin resistance combined with hyperinsulinemia followed by suppression of insulin secretion from pancreatic β-cells. Mitochondria play a central role in β-cells by sensing glucose and also by mediating the suppression of insulin secretion in T2D. Here, we will summarize the evidence accumulated for the roles of β-cells mitochondria in T2D. We will present an updated view on how mitochondria in β-cells have been associated with T2D, from the genetic, bioenergetic, redox and structural points of view. The emerging picture is that mitochondrial structure and dysfunction directly contribute to β-cell function and in the pathogenesis of T2D.
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Affiliation(s)
- Guy Las
- Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer-Sheva, Israel
| | - Marcus F Oliveira
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal Do Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil.
| | - Orian S Shirihai
- Division of Endocrinology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
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21
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Magge SN, Zemel BS, Pipan ME, Gidding SS, Kelly A. Cardiometabolic Risk and Body Composition in Youth With Down Syndrome. Pediatrics 2019; 144:peds.2019-0137. [PMID: 31315916 PMCID: PMC6855833 DOI: 10.1542/peds.2019-0137] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/17/2019] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Whether BMI captures adiposity and cardiometabolic risk in Down syndrome (DS), a condition associated with obesity, short stature, and altered body proportions, is not known. We compared cardiometabolic risk measures in youth with DS and typically developing matched controls. METHODS Youth with (n = 150) and without (n = 103) DS of comparable age (10-20 years), sex, race, ethnicity, and BMI percentile underwent whole-body dual-energy X-ray absorptiometry, fasting glucose, insulin, lipids, lipoprotein particles, inflammatory factors, and when BMI percentile ≥85, an oral glucose tolerance test. RESULTS Sixty-four percent of youth with DS had BMI percentile ≥85. Among these, no difference in glucose, insulin, or insulin resistance was detected, but prediabetes was more prevalent with DS (26.4% vs 10.3%; P = .025) after adjustment for demographics, pubertal status, and BMI z score (odds ratio = 3.2; P = .026). Among all participants, those with DS had higher low-density lipoprotein cholesterol (median 107 [interquartile range 89-128] vs 88.5 [79-103] mg/dL; P < .00005), triglycerides (89.5 [73-133] vs 71.5 [56-104] mg/dL; P < .00005), non-high-density lipoprotein cholesterol (non-HDL-C; 128 [104-153] vs 107 [92-123] mg/dL; P < .00005), and triglycerides/HDL-C (2.2 [1.6-3.4] vs 1.7 [1.1-2.5] mg/dL; P = .0003) and lower levels of HDL-C (41 [36.5-47] vs 45 [37-53] mg/dL; P = .012). DS youth had higher high-sensitivity C-reactive protein, interleukin-6, small low-density lipoprotein particles (LDL-P), and total LDL-P, but similar LDL-P size. Youth with DS had less visceral fat (VFAT), fat mass, and lean mass for BMI z score, but greater VFAT at higher fat mass. However, VFAT did not fully explain the increased prevalence of dyslipidemia or prediabetes in youth with DS. CONCLUSIONS Despite similar insulin resistance, youth with DS had greater prevalence of dyslipidemia and prediabetes than typically developing youth, which was not fully explained by VFAT.
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Affiliation(s)
- Sheela N. Magge
- Division of Endocrinology and Diabetes, School of Medicine and Health Sciences, The George Washington University and Clinical and Translational Science Institute at Children’s National, Children’s Research Institute, Children’s National Health System, Washington, District of Columbia; Divisions of
| | - Babette S. Zemel
- Gastroenterology, Hepatology, and Nutrition,,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania; and
| | - Mary E. Pipan
- Developmental Behavioral Pediatrics, and,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania; and
| | | | - Andrea Kelly
- Endocrinology and Diabetes, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania;,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania; and
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22
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Zhu L, Dattaroy D, Pham J, Wang L, Barella LF, Cui Y, Wilkins KJ, Roth BL, Hochgeschwender U, Matschinsky FM, Kaestner KH, Doliba NM, Wess J. Intra-islet glucagon signaling is critical for maintaining glucose homeostasis. JCI Insight 2019; 5:127994. [PMID: 31012868 DOI: 10.1172/jci.insight.127994] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Glucagon, a hormone released from pancreatic alpha-cells, plays a key role in maintaining proper glucose homeostasis and has been implicated in the pathophysiology of diabetes. In vitro studies suggest that intra-islet glucagon can modulate the function of pancreatic beta-cells. However, because of the lack of suitable experimental tools, the in vivo physiological role of this intra-islet cross-talk has remained elusive. To address this issue, we generated a novel mouse model that selectively expressed an inhibitory designer G protein-coupled receptor (Gi DREADD) in α-cells only. Drug-induced activation of this inhibitory designer receptor almost completely shut off glucagon secretion in vivo, resulting in significantly impaired insulin secretion, hyperglycemia, and glucose intolerance. Additional studies with mouse and human islets indicated that intra-islet glucagon stimulates insulin release primarily by activating β-cell GLP-1 receptors. These new findings strongly suggest that intra-islet glucagon signaling is essential for maintaining proper glucose homeostasis in vivo. Our work may pave the way toward the development of novel classes of antidiabetic drugs that act by modulating intra-islet cross-talk between α- and β-cells.
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Affiliation(s)
- Lu Zhu
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
| | - Diptadip Dattaroy
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
| | - Jonathan Pham
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
| | - Lingdi Wang
- Laboratory of Mitochondrial Biology and Metabolism, National Heart, Lung and Blood Institute, Bethesda, Maryland, USA
| | - Luiz F Barella
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
| | - Yinghong Cui
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
| | - Kenneth J Wilkins
- Biostatistics Program, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland, USA
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Ute Hochgeschwender
- Neuroscience Program and College of Medicine, Central Michigan University, Mt. Pleasant, Michigan, USA
| | - Franz M Matschinsky
- Institute of Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Klaus H Kaestner
- Institute of Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nicolai M Doliba
- Institute of Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jürgen Wess
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA
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23
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Wilson DF, Matschinsky FM. Oxygen dependence of glucose sensing: role in glucose homeostasis and related pathology. J Appl Physiol (1985) 2019; 126:1746-1755. [PMID: 30991014 DOI: 10.1152/japplphysiol.00047.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
In glucose homeostasis, glucose concentration is sensed by its metabolism through glucokinase (GCK) and oxidative phosphorylation. Because oxidative phosphorylation is an integral part of the sensory system, glucose sensing is necessarily dependent on oxygen pressure. Much of the dependence on oxygen is suppressed by location of glucose sensing cells in tissues with well-regulated blood flow. In healthy individuals the oxygen dependence is primarily observed in response to transient global hypoxia events such as during birth or transition to high altitude. The GCK sensing system is, however, used to control release of both insulin and glucagon, the preeminant hormonal regulators of blood glucose, as well as glucose sensitive neuronal activity. Suppression of oxygen delivery to glucose-sensing cells or interference with regulation of tissue blood flow by either local or systemic causes, stresses the glucose regulatory system. This is true whether the stress is imposed locally, such as by altered oxygen delivery to the pancreas, or globally, as in pulmonary insufficiency or exposure to high altitude. It may be expected that chronic application of this stress predisposes individuals to developing diabetes. Type 2 diabetes is a broad class of diseases characterized by disturbance of glucose homeostasis, i.e., having either hyperglycemia and/or decreased sensitivity to insulin. Given the role of oxidative phosphorylation in glucose sensing, tissue oxygen deprivation may predispose individuals to developing diabetes as well as contributing to the disease itself. This is particularly true in age-related diabetes because the incidence of vascular insufficiency increases markedly with increasing age. NEW & NOTEWORTHY Glucose sensing requires glucose metabolism through glycolysis and oxidative phosphorylation. Dependence of the latter on oxygen concentration imposes an oxygen dependence on glucose sensing. We have used a validated computational model to quantify that dependence. Evidence is presented that tissue oxygenation plays an important role in predisposition of individuals to developing type 2 diabetes and in progression of the disease.
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Affiliation(s)
- David F Wilson
- Perelman School of Medicine, Department of Biochemistry and Biophysics, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Franz M Matschinsky
- Perelman School of Medicine, Department of Biochemistry and Biophysics, University of Pennsylvania , Philadelphia, Pennsylvania
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24
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Matschinsky FM, Wilson DF. The Central Role of Glucokinase in Glucose Homeostasis: A Perspective 50 Years After Demonstrating the Presence of the Enzyme in Islets of Langerhans. Front Physiol 2019; 10:148. [PMID: 30949058 PMCID: PMC6435959 DOI: 10.3389/fphys.2019.00148] [Citation(s) in RCA: 150] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 02/07/2019] [Indexed: 01/05/2023] Open
Abstract
It is hypothesized that glucokinase (GCK) is the glucose sensor not only for regulation of insulin release by pancreatic β-cells, but also for the rest of the cells that contribute to glucose homeostasis in mammals. This includes other cells in endocrine pancreas (α- and δ-cells), adrenal gland, glucose sensitive neurons, entero-endocrine cells, and cells in the anterior pituitary. Glucose transport is by facilitated diffusion and is not rate limiting. Once inside, glucose is phosphorylated to glucose-6-phosphate by GCK in a reaction that is dependent on glucose throughout the physiological range of concentrations, is irreversible, and not product inhibited. High glycerol phosphate shuttle, pyruvate dehydrogenase, and pyruvate carboxylase activities, combined with low pentose-P shunt, lactate dehydrogenase, plasma membrane monocarboxylate transport, and glycogen synthase activities constrain glucose-6-phosphate to being metabolized through glycolysis. Under these conditions, glycolysis produces mostly pyruvate and little lactate. Pyruvate either enters the citric acid cycle through pyruvate dehydrogenase or is carboxylated by pyruvate carboxylase. Reducing equivalents from glycolysis enter oxidative phosphorylation through both the glycerol phosphate shuttle and citric acid cycle. Raising glucose concentration increases intramitochondrial [NADH]/[NAD+] and thereby the energy state ([ATP]/[ADP][Pi]), decreasing [Mg2+ADP] and [AMP]. [Mg2+ADP] acts through control of KATP channel conductance, whereas [AMP] acts through regulation of AMP-dependent protein kinase. Specific roles of different cell types are determined by the diverse molecular mechanisms used to couple energy state to cell specific responses. Having a common glucose sensor couples complementary regulatory mechanisms into a tightly regulated and stable glucose homeostatic network.
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Affiliation(s)
- Franz M Matschinsky
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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25
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Henquin JC. Influence of organ donor attributes and preparation characteristics on the dynamics of insulin secretion in isolated human islets. Physiol Rep 2019. [PMID: 29536672 PMCID: PMC5849575 DOI: 10.14814/phy2.13646] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In vitro studies of human pancreatic islets are critical for understanding normal insulin secretion and its perturbations in diabetic β-cells, but the influence of islet preparation characteristics and organ donor attributes in such experiments is poorly documented. Preparations from normal donors were tested with a standardized protocol evaluating dynamic insulin secretion induced by glucose, tolbutamide, and cAMP (forskolin). Secretion rates, normalized to insulin content (fractional insulin secretion), were analyzed as a function of preparation and donor characteristics. Low purity (25-45%) of the preparation (n = 8) blunted the first phase of insulin secretion induced by glucose or tolbutamide and increased basal secretion, resulting in threefold lower stimulation index than in more pure (55-95%) preparations (n = 43). In these more pure preparations, cold ischemia time (1-13 h) before pancreas digestion did not impact insulin secretion. Islet size (estimated by the islet size index) did not influence the dynamics of secretion, but fractional insulin secretion rates were greater in large than small islets, and positively correlated with islet size. Age of the donors (20-68 years) had no influence on islet size and insulin content or on dynamics and amplitude of insulin secretion, which were also similar in islets from male and female donors. In contrast, islet size and islet insulin content (normalized for size), and basal or stimulated insulin secretion positively correlated with Body-Mass Index (19-33). These results contradict previous reports on the impact of donor age and islet size and point to possible confounding effects of donor BMI in insulin secretion studies with isolated human islets.
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Affiliation(s)
- Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium
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26
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Zhang E, Mohammed Al-Amily I, Mohammed S, Luan C, Asplund O, Ahmed M, Ye Y, Ben-Hail D, Soni A, Vishnu N, Bompada P, De Marinis Y, Groop L, Shoshan-Barmatz V, Renström E, Wollheim CB, Salehi A. Preserving Insulin Secretion in Diabetes by Inhibiting VDAC1 Overexpression and Surface Translocation in β Cells. Cell Metab 2019; 29:64-77.e6. [PMID: 30293774 PMCID: PMC6331340 DOI: 10.1016/j.cmet.2018.09.008] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 07/12/2018] [Accepted: 09/08/2018] [Indexed: 02/08/2023]
Abstract
Type 2 diabetes (T2D) develops after years of prediabetes during which high glucose (glucotoxicity) impairs insulin secretion. We report that the ATP-conducting mitochondrial outer membrane voltage-dependent anion channel-1 (VDAC1) is upregulated in islets from T2D and non-diabetic organ donors under glucotoxic conditions. This is caused by a glucotoxicity-induced transcriptional program, triggered during years of prediabetes with suboptimal blood glucose control. Metformin counteracts VDAC1 induction. VDAC1 overexpression causes its mistargeting to the plasma membrane of the insulin-secreting β cells with loss of the crucial metabolic coupling factor ATP. VDAC1 antibodies and inhibitors prevent ATP loss. Through direct inhibition of VDAC1 conductance, metformin, like specific VDAC1 inhibitors and antibodies, restores the impaired generation of ATP and glucose-stimulated insulin secretion in T2D islets. Treatment of db/db mice with VDAC1 inhibitor prevents hyperglycemia, and maintains normal glucose tolerance and physiological regulation of insulin secretion. Thus, β cell function is preserved by targeting the novel diabetes executer protein VDAC1.
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Affiliation(s)
- Enming Zhang
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Israa Mohammed Al-Amily
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Sarheed Mohammed
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Cheng Luan
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Olof Asplund
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Meftun Ahmed
- Academic Hospital Uppsala University, Uppsala, Sweden
| | - Yingying Ye
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Danya Ben-Hail
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Arvind Soni
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Neelanjan Vishnu
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Pradeep Bompada
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Yang De Marinis
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Leif Groop
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden; Finnish Institute for Molecular Medicine, Helsinki University, Helsinki, Finland
| | - Varda Shoshan-Barmatz
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Erik Renström
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden
| | - Claes B Wollheim
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden; Department of Cell Physiology and Metabolism, University Medical Centre, 1 rue Michel-Servet, Geneva 4, Switzerland.
| | - Albert Salehi
- Department of Clinical Sciences, Malmö, Lund University, Jan Waldenströms Gata 35, Malmö 214 28, Sweden.
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27
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Smith KE, Purvis WG, Davis MA, Min CG, Cooksey AM, Weber CS, Jandova J, Price ND, Molano DS, Stanton JB, Kelly AC, Steyn LV, Lynch RM, Limesand SW, Alexander M, Lakey JRT, Seeberger K, Korbutt GS, Mueller KR, Hering BJ, McCarthy FM, Papas KK. In vitro characterization of neonatal, juvenile, and adult porcine islet oxygen demand, β-cell function, and transcriptomes. Xenotransplantation 2018; 25:e12432. [PMID: 30052287 DOI: 10.1111/xen.12432] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 04/20/2018] [Accepted: 05/24/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND There is currently a shortage of human donor pancreata which limits the broad application of islet transplantation as a treatment for type 1 diabetes. Porcine islets have demonstrated potential as an alternative source, but a study evaluating islets from different donor ages under unified protocols has yet to be conducted. METHODS Neonatal porcine islets (NPI; 1-3 days), juvenile porcine islets (JPI; 18-21 days), and adult porcine islets (API; 2+ years) were compared in vitro, including assessments of oxygen consumption rate, membrane integrity determined by FDA/PI staining, β-cell proliferation, dynamic glucose-stimulated insulin secretion, and RNA sequencing. RESULTS Oxygen consumption rate normalized to DNA was not significantly different between ages. Membrane integrity was age dependent, and API had the highest percentage of intact cells. API also had the highest glucose-stimulated insulin secretion response during a dynamic insulin secretion assay and had 50-fold higher total insulin content compared to NPI and JPI. NPI and JPI had similar glucose responsiveness, β-cell percentage, and β-cell proliferation rate. Transcriptome analysis was consistent with physiological assessments. API transcriptomes were enriched for cellular metabolic and insulin secretory pathways, while NPI exhibited higher expression of genes associated with proliferation. CONCLUSIONS The oxygen demand, membrane integrity, β-cell function and proliferation, and transcriptomes of islets from API, JPI, and NPI provide a comprehensive physiological comparison for future studies. These assessments will inform the optimal application of each age of porcine islet to expand the availability of islet transplantation.
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Affiliation(s)
- Kate E Smith
- Department of Physiological Sciences, University of Arizona, Tucson, AZ, USA.,Department of Surgery, University of Arizona, Tucson, AZ, USA
| | | | - Melissa A Davis
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Catherine G Min
- Department of Physiological Sciences, University of Arizona, Tucson, AZ, USA.,Department of Surgery, University of Arizona, Tucson, AZ, USA
| | - Amanda M Cooksey
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Craig S Weber
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Jana Jandova
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | | | - Diana S Molano
- Department of Surgery, University of Arizona, Tucson, AZ, USA
| | | | - Amy C Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Leah V Steyn
- Department of Surgery, University of Arizona, Tucson, AZ, USA
| | - Ronald M Lynch
- Department of Physiology, University of Arizona, Tucson, AZ, USA
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
| | - Michael Alexander
- Department of Surgery, University of California-Irvine, Orange, CA, USA
| | | | - Karen Seeberger
- Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AL, Canada
| | - Gregory S Korbutt
- Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AL, Canada
| | - Kate R Mueller
- Schulze Diabetes Institute, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Bernhard J Hering
- Schulze Diabetes Institute, Department of Surgery, University of Minnesota, Minneapolis, MN, USA
| | - Fiona M McCarthy
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, USA
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Gerencser AA. Metabolic activation-driven mitochondrial hyperpolarization predicts insulin secretion in human pancreatic beta-cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:817-828. [PMID: 29886047 DOI: 10.1016/j.bbabio.2018.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/18/2018] [Accepted: 06/05/2018] [Indexed: 12/31/2022]
Abstract
Mitochondrial metabolism plays a central role in insulin secretion in pancreatic beta-cells. Generation of protonmotive force and ATP synthesis from glucose-originated pyruvate are critical steps in the canonical pathway of glucose-stimulated insulin secretion. Mitochondrial metabolism is intertwined with pathways that are thought to amplify insulin secretion with mechanisms distinct from the canonical pathway, and the relative importance of these two pathways is controversial. Here I show that glucose-induced mitochondrial membrane potential (MMP) hyperpolarization is necessary for, and predicts, the rate of insulin secretion in primary cultured human beta-cells. When glucose concentration is elevated, increased metabolism results in a substantial MMP hyperpolarization, as well as in increased rates of ATP synthesis and turnover marked by faster cell respiration. Using modular kinetic analysis I explored what properties of cellular energy metabolism enable a large glucose-induced change in MMP in human beta-cells. I found that an ATP-dependent pathway activates glucose or substrate oxidation, acting as a positive feedback in energy metabolism. This activation mechanism is essential for concomitant fast respiration and high MMP, and for a high magnitude glucose-induced MMP hyperpolarization and therefore for insulin secretion.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States; Image Analyst Software, 43 Nova Lane, Novato, CA 94945, United States.
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Proks P, Kramer H, Haythorne E, Ashcroft FM. Binding of sulphonylureas to plasma proteins - A KATP channel perspective. PLoS One 2018; 13:e0197634. [PMID: 29772022 PMCID: PMC5957440 DOI: 10.1371/journal.pone.0197634] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 05/04/2018] [Indexed: 12/25/2022] Open
Abstract
Sulphonylurea drugs stimulate insulin secretion from pancreatic β-cells primarily by inhibiting ATP sensitive potassium (KATP) channels in the β-cell membrane. The effective sulphonylurea concentration at its site of action is significantly attenuated by binding to serum albumin, which makes it difficult to compare in vitro and in vivo data. We therefore measured the ability of gliclazide and glibenclamide to inhibit KATP channels and stimulate insulin secretion in the presence of serum albumin. We used this data, together with estimates of free drug concentrations from binding studies, to predict the extent of sulphonylurea inhibition of KATP channels at therapeutic concentrations in vivo. KATP currents from mouse pancreatic β-cells and Xenopus oocytes were measured using the patch-clamp technique. Gliclazide and glibenclamide binding to human plasma were determined in spiked plasma samples using an ultrafiltration-mass spectrometry approach. Bovine serum albumin (60g/l) produced a mild, non-significant reduction of gliclazide block of KATP currents in pancreatic β-cells and Xenopus oocytes. In contrast, glibenclamide inhibition of recombinant KATP channels was dramatically suppressed by albumin (predicted free drug concentration <0.1%). Insulin secretion was also reduced. Free concentrations of gliclazide and glibenclamide in the presence of human plasma measured in binding experiments were 15% and 0.05%, respectively. Our data suggest the free concentration of glibenclamide in plasma is too low to account for the drug’s therapeutic effect. In contrast, the free gliclazide concentration in plasma is high enough to close KATP channels and stimulate insulin secretion.
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Affiliation(s)
- Peter Proks
- Oxford Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Holger Kramer
- Oxford Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Elizabeth Haythorne
- Oxford Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M. Ashcroft
- Oxford Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- * E-mail:
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30
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Control of pancreatic β-cell bioenergetics. Biochem Soc Trans 2018; 46:555-564. [PMID: 29666215 DOI: 10.1042/bst20170505] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 03/06/2018] [Accepted: 03/08/2018] [Indexed: 12/12/2022]
Abstract
The canonical model of glucose-stimulated insulin secretion (GSIS) by pancreatic β-cells predicts a glucose-induced rise in the cytosolic ATP/ADP ratio. Such bioenergetic sensitivity to metabolic fuel is unusual as it implies that ATP flux is governed, to a significant extent, by ATP supply, while it is predominantly demand-driven in other cell types. Metabolic control is generally shared between different processes, but potential control of ATP consumption over β-cell bioenergetics has been largely ignored to date. The present paper offers a brief overview of experimental evidence that demonstrates ATP flux control by glucose-fuelled oxidative phosphorylation. Based on old and new data, it is argued that ATP supply does not hold exclusive control over ATP flux, but shares it with ATP demand, and that the distribution of control is flexible. Quantification of the bioenergetic control distribution will be important from basic and clinical perspectives, but precise measurement of the cytosolic ATP/ADP ratio is complicated by adenine nucleotide compartmentalisation. Metabolic control analysis of β-cell bioenergetics will likely clarify the mechanisms by which glucose and fatty acids amplify and potentiate GSIS, respectively. Moreover, such analysis may offer hints as to how ATP flux control shifts from ATP supply to ATP demand during the development of type 2 diabetes, and why prolonged sulfonylurea treatment causes β-cell deterioration.
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Wilson DF, Cember ATJ, Matschinsky FM. Glutamate dehydrogenase: role in regulating metabolism and insulin release in pancreatic β-cells. J Appl Physiol (1985) 2018; 125:419-428. [PMID: 29648519 DOI: 10.1152/japplphysiol.01077.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Regulation of insulin release and glucose homeostasis by pancreatic β-cells is dependent on the metabolism of glucose by glucokinase (GK) and the influence of that activity on oxidative phosphorylation. Genetic alterations that result in hyperactivity of mitochondrial glutamate dehydrogenase (GDH-1) can cause hypoglycemia-hyperammonemia following high protein meals, but the role of GDH-1 remains poorly understood. GDH-1 activity is strongly inhibited by GTP, to near zero in the absence of ADP, and cooperatively activated ( n = 2.3) by ADP. The dissociation constant for ADP is near 200 µM in vivo, but leucine and its nonmetabolized analog 2-amino-2-norbornane-carboxylic acid (BCH) can activate GDH-1 by increasing the affinity for ADP. Under physiological conditions, as [ADP] increases GDH-1 activity remains very low until ~35 µM (threshold) and then increases rapidly. A model for GDH-1 and its regulation has been combined with a previously published model for glucose sensing that coupled GK activity and oxidative phosphorylation. The combined model (GK-GDH-core) shows that GK activity determines the energy state ([ATP]/[ADP][Pi]) in β-cells for glucose concentrations > 5 mM ([ADP] < 35 µM). As glucose falls < 5 mM the [ADP]-dependent increase in GDH-1 activity prevents [ADP] from rising above ~70 µM. Thus, GDH-1 dynamically buffers β-cell energy metabolism during hypoglycemia, maintaining the energy state and the basal rate of insulin release. GDH-1 hyperactivity suppresses the normal increase in [ADP] in hypoglycemia. This leads to hypoglycemia following a high protein meal by increasing the basal rate of insulin release (β-cells) and decreasing glucagon release (α-cells). NEW & NOTEWORTHY A model of β-cell metabolism and regulation of insulin release is presented. The model integrates regulation of oxidative phosphorylation, glucokinase (GK), and glutamate dehydrogenase (GDH-1). GDH-1 is near equilibrium under physiological conditions, but the activity is inhibited by GTP. In hypoglycemia, however, GK activity is low and [ADP], a potent activator of GDH-1, increases. Reducing equivalents from GDH dynamically buffers the intramitochondrial [NADH]/[NAD+], and thereby the energy state, preventing hypoglycemia-induced substrate deprivation.
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Abigail T J Cember
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
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Wilson DF, Cember ATJ, Matschinsky FM. The thermodynamic basis of glucose-stimulated insulin release: a model of the core mechanism. Physiol Rep 2018; 5:5/12/e13327. [PMID: 28655753 PMCID: PMC5492210 DOI: 10.14814/phy2.13327] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 05/23/2017] [Accepted: 05/24/2017] [Indexed: 11/24/2022] Open
Abstract
A model for glucose sensing by pancreatic β-cells is developed and compared with the available experimental data. The model brings together mathematical representations for the activities of the glucose sensor, glucokinase, and oxidative phosphorylation. Glucokinase produces glucose 6-phosphate (G-6-P) in an irreversible reaction that determines glycolytic flux. The primary products of glycolysis are NADH and pyruvate. The NADH is reoxidized and the reducing equivalents transferred to oxidative phosphorylation by the glycerol phosphate shuttle, and some of the pyruvate is oxidized by pyruvate dehydrogenase and enters the citric acid cycle. These reactions are irreversible and result in a glucose concentration-dependent reduction of the intramitochondrial NAD pool. This increases the electrochemical energy coupled to ATP synthesis and thereby the cellular energy state ([ATP]/[ADP][Pi]). ATP and Pi are 10-100 times greater than ADP, so the increase in energy state is primarily through decrease in ADP The decrease in ADP is considered responsible for altering ion channel conductance and releasing insulin. Applied to the reported glucose concentration-dependent release of insulin by perifused islet preparations (Doliba et al. 2012), the model predicts that the dependence of insulin release on ADP is strongly cooperative with a threshold of about 30 μmol/L and a negative Hill coefficient near -5.5. The predicted cellular energy state, ADP, creatine phosphate/creatine ratio, and cytochrome c reduction, including their dependence on glucose concentration, are consistent with experimental data. The ability of the model to predict behavior consistent with experiment is an invaluable resource for understanding glucose sensing and planning experiments.
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Abigail T J Cember
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Abstract
Islets of Langerhans are islands of endocrine cells scattered throughout the pancreas. A number of new studies have pointed to the potential for conversion of non-β islet cells in to insulin-producing β-cells to replenish β-cell mass as a means to treat diabetes. Understanding normal islet cell mass and function is important to help advance such treatment modalities: what should be the target islet/β-cell mass, does islet architecture matter to energy homeostasis, and what may happen if we lose a particular population of islet cells in favour of β-cells? These are all questions to which we will need answers for islet replacement therapy by transdifferentiation of non-β islet cells to be a reality in humans. We know a fair amount about the biology of β-cells but not quite as much about the other islet cell types. Until recently, we have not had a good grasp of islet mass and distribution in the human pancreas. In this review, we will look at current data on islet cells, focussing more on non-β cells, and on human pancreatic islet mass and distribution.
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Affiliation(s)
- Gabriela Da Silva Xavier
- Section of Functional Genomics and Cell Biology, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK.
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Edgbaston B15 2TT, UK.
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Riopel M, Seo JB, Bandyopadhyay GK, Li P, Wollam J, Chung H, Jung SR, Murphy A, Wilson M, de Jong R, Patel S, Balakrishna D, Bilakovics J, Fanjul A, Plonowski A, Koh DS, Larson CJ, Olefsky JM, Lee YS. Chronic fractalkine administration improves glucose tolerance and pancreatic endocrine function. J Clin Invest 2018; 128:1458-1470. [PMID: 29504946 DOI: 10.1172/jci94330] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 01/18/2018] [Indexed: 01/09/2023] Open
Abstract
We have previously reported that the fractalkine (FKN)/CX3CR1 system represents a novel regulatory mechanism for insulin secretion and β cell function. Here, we demonstrate that chronic administration of a long-acting form of FKN, FKN-Fc, can exert durable effects to improve glucose tolerance with increased glucose-stimulated insulin secretion and decreased β cell apoptosis in obese rodent models. Unexpectedly, chronic FKN-Fc administration also led to decreased α cell glucagon secretion. In islet cells, FKN inhibited ATP-sensitive potassium channel conductance by an ERK-dependent mechanism, which triggered β cell action potential (AP) firing and decreased α cell AP amplitude. This results in increased glucose-stimulated insulin secretion and decreased glucagon secretion. Beyond its islet effects, FKN-Fc also exerted peripheral effects to enhance hepatic insulin sensitivity due to inhibition of glucagon action. In hepatocytes, FKN treatment reduced glucagon-stimulated cAMP production and CREB phosphorylation in a pertussis toxin-sensitive manner. Together, these results raise the possibility of use of FKN-based therapy to improve type 2 diabetes by increasing both insulin secretion and insulin sensitivity.
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Affiliation(s)
- Matthew Riopel
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA
| | - Jong Bae Seo
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA.,Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
| | - Gautam K Bandyopadhyay
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA
| | - Pingping Li
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA.,State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Joshua Wollam
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA
| | - Heekyung Chung
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA
| | - Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
| | - Anne Murphy
- Department of Pharmacology, UCSD, La Jolla, California, USA
| | - Maria Wilson
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA
| | - Ron de Jong
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA
| | - Sanjay Patel
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA
| | - Deepika Balakrishna
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA
| | - James Bilakovics
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA
| | - Andrea Fanjul
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA
| | - Artur Plonowski
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA
| | - Duk-Su Koh
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
| | - Christopher J Larson
- Cardiovascular and Metabolic Diseases Drug Discovery Unit, Takeda Pharmaceuticals, San Diego, California, USA.,Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Jerrold M Olefsky
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA
| | - Yun Sok Lee
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California, USA.,Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 424] [Impact Index Per Article: 70.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Skelin Klemen M, Dolenšek J, Slak Rupnik M, Stožer A. The triggering pathway to insulin secretion: Functional similarities and differences between the human and the mouse β cells and their translational relevance. Islets 2017; 9:109-139. [PMID: 28662366 PMCID: PMC5710702 DOI: 10.1080/19382014.2017.1342022] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In β cells, stimulation by metabolic, hormonal, neuronal, and pharmacological factors is coupled to secretion of insulin through different intracellular signaling pathways. Our knowledge about the molecular machinery supporting these pathways and the patterns of signals it generates comes mostly from rodent models, especially the laboratory mouse. The increased availability of human islets for research during the last few decades has yielded new insights into the specifics in signaling pathways leading to insulin secretion in humans. In this review, we follow the most central triggering pathway to insulin secretion from its very beginning when glucose enters the β cell to the calcium oscillations it produces to trigger fusion of insulin containing granules with the plasma membrane. Along the way, we describe the crucial building blocks that contribute to the flow of information and focus on their functional role in mice and humans and on their translational implications.
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Affiliation(s)
- Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Marjan Slak Rupnik
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Institute of Physiology; Center for Physiology and Pharmacology; Medical University of Vienna; Vienna, Austria
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
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37
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Lu M, Li C. Nutrient sensing in pancreatic islets: lessons from congenital hyperinsulinism and monogenic diabetes. Ann N Y Acad Sci 2017; 1411:65-82. [PMID: 29044608 DOI: 10.1111/nyas.13448] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 07/05/2017] [Accepted: 07/14/2017] [Indexed: 12/14/2022]
Abstract
Pancreatic beta cells sense changes in nutrients during the cycles of fasting and feeding and release insulin accordingly to maintain glucose homeostasis. Abnormal beta cell nutrient sensing resulting from gene mutations leads to hypoglycemia or diabetes. Glucokinase (GCK) plays a key role in beta cell glucose sensing. As one form of congenital hyperinsulinism (CHI), activating mutations of GCK result in a decreased threshold for glucose-stimulated insulin secretion and hypoglycemia. In contrast, inactivating mutations of GCK result in diabetes, including a mild form (MODY2) and a severe form (permanent neonatal diabetes mellitus (PNDM)). Mutations of beta cell ion channels involved in insulin secretion regulation also alter glucose sensing. Activating or inactivating mutations of ATP-dependent potassium (KATP ) channel genes result in severe but completely opposite clinical phenotypes, including PNDM and CHI. Mutations of the other ion channels, including voltage-gated potassium channels (Kv 7.1) and voltage-gated calcium channels, also lead to abnormal glucose sensing and CHI. Furthermore, amino acids can stimulate insulin secretion in a glucose-independent manner in some forms of CHI, including activating mutations of the glutamate dehydrogenase gene, HDAH deficiency, and inactivating mutations of KATP channel genes. These genetic defects have provided insight into a better understanding of the complicated nature of beta cell fuel-sensing mechanisms.
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Affiliation(s)
- Ming Lu
- Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pediatrics & Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong, China
| | - Changhong Li
- Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.,Department of Pediatrics & Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Henquin JC, Dufrane D, Gmyr V, Kerr-Conte J, Nenquin M. Pharmacological approach to understanding the control of insulin secretion in human islets. Diabetes Obes Metab 2017; 19:1061-1070. [PMID: 28116849 DOI: 10.1111/dom.12887] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 01/12/2017] [Accepted: 01/19/2017] [Indexed: 11/29/2022]
Abstract
AIMS To understand better the control of insulin secretion by human β cells and to identify similarities to and differences from rodent models. METHODS Dynamic insulin secretion was measured in perifused human islets treated with pharmacological agents of known modes of action. RESULTS Glucokinase activation (Ro28-1675) lowered the glucose threshold for stimulation of insulin secretion to 1 mmol/L (G1), augmented the response to G3-G5 but not to G8-G15, whereas tolbutamide remained active in G20, which indicates that not all KATP channels were closed by high glucose concentrations. An almost 2-fold greater response to G15 than to supramaximal tolbutamide in G3 or to KCl+diazoxide in G15 vs G3 quantified the contribution of metabolic amplification to insulin secretion. Both disruption (latrunculin-B) and stabilization (jasplakinolide) of microfilaments augmented insulin secretion without affecting metabolic amplification. Tolbutamide-induced insulin secretion was consistently greater in G10 than G3, with a threshold at 1 and maximum at 10 µmol/L tolbutamide in G10, vs 10 and 25 µmol/L in G3. Sulphonylurea effects were thus clearly glucose-dependent. Insulin secretion was also increased by inhibiting K channels other than KATP channels: Kv or BK channels (tetraethylammonium), TASK-1 channels (ML-365) and SK4 channels (TRAM-34). Opening KATP channels with diazoxide inhibited glucose-induced insulin secretion with half maximum inhibitory concentrations of 9.6 and 24 µmol/L at G7 and G15. Blockade of L-type Ca channels (nimodipine) abolished insulin secretion, whereas a blocker of T-type Ca channels (NNC-55-0396) was ineffective at specific concentrations. Blockade of Na channels (tetrodotoxin) did not affect glucose-induced insulin secretion. CONCLUSIONS In addition to sharing a KATP channel-dependent triggering pathway and a metabolic amplifying pathway, human and rodent β cells were found to display more similarities than differences in the control of insulin secretion.
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Affiliation(s)
- Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium
| | - Denis Dufrane
- Endocrine Cell Therapy Unit, University Clinics Saint-Luc, University of Louvain, Brussels, Belgium
| | - Valery Gmyr
- Institut National de la Santé et de la Recherche Médicale U1190, Translational Research for Diabetes, and European Genomic Institute for Diabetes, University of Lille, Lille, France
| | - Julie Kerr-Conte
- Institut National de la Santé et de la Recherche Médicale U1190, Translational Research for Diabetes, and European Genomic Institute for Diabetes, University of Lille, Lille, France
| | - Myriam Nenquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium
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Li C, Ackermann AM, Boodhansingh KE, Bhatti TR, Liu C, Schug J, Doliba N, Han B, Cosgrove KE, Banerjee I, Matschinsky FM, Nissim I, Kaestner KH, Naji A, Adzick NS, Dunne MJ, Stanley CA, De León DD. Functional and Metabolomic Consequences of K ATP Channel Inactivation in Human Islets. Diabetes 2017; 66:1901-1913. [PMID: 28442472 PMCID: PMC5482088 DOI: 10.2337/db17-0029] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 04/15/2017] [Indexed: 12/17/2022]
Abstract
Loss-of-function mutations of β-cell KATP channels cause the most severe form of congenital hyperinsulinism (KATPHI). KATPHI is characterized by fasting and protein-induced hypoglycemia that is unresponsive to medical therapy. For a better understanding of the pathophysiology of KATPHI, we examined cytosolic calcium ([Ca2+] i ), insulin secretion, oxygen consumption, and [U-13C]glucose metabolism in islets isolated from the pancreases of children with KATPHI who required pancreatectomy. Basal [Ca2+] i and insulin secretion were higher in KATPHI islets compared with controls. Unlike controls, insulin secretion in KATPHI islets increased in response to amino acids but not to glucose. KATPHI islets have an increased basal rate of oxygen consumption and mitochondrial mass. [U-13C]glucose metabolism showed a twofold increase in alanine levels and sixfold increase in 13C enrichment of alanine in KATPHI islets, suggesting increased rates of glycolysis. KATPHI islets also exhibited increased serine/glycine and glutamine biosynthesis. In contrast, KATPHI islets had low γ-aminobutyric acid (GABA) levels and lacked 13C incorporation into GABA in response to glucose stimulation. The expression of key genes involved in these metabolic pathways was significantly different in KATPHI β-cells compared with control, providing a mechanism for the observed changes. These findings demonstrate that the pathophysiology of KATPHI is complex, and they provide a framework for the identification of new potential therapeutic targets for this devastating condition.
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Affiliation(s)
- Changhong Li
- Division of Endocrinology and Diabetes, Department of Pediatrics, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Amanda M Ackermann
- Division of Endocrinology and Diabetes, Department of Pediatrics, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Kara E Boodhansingh
- Division of Endocrinology and Diabetes, Department of Pediatrics, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Tricia R Bhatti
- Department of Pathology, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Chengyang Liu
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Jonathan Schug
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Nicolai Doliba
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Bing Han
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, U.K
| | - Karen E Cosgrove
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, U.K
| | - Indraneel Banerjee
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, U.K
| | - Franz M Matschinsky
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Itzhak Nissim
- Division of Metabolism, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Klaus H Kaestner
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Ali Naji
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - N Scott Adzick
- Department of Surgery, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Mark J Dunne
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, U.K
| | - Charles A Stanley
- Division of Endocrinology and Diabetes, Department of Pediatrics, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Diva D De León
- Division of Endocrinology and Diabetes, Department of Pediatrics, The Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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Chong CR, Clarke K, Levelt E. Metabolic Remodeling in Diabetic Cardiomyopathy. Cardiovasc Res 2017; 113:422-430. [PMID: 28177068 PMCID: PMC5412022 DOI: 10.1093/cvr/cvx018] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/02/2017] [Indexed: 02/07/2023] Open
Abstract
Diabetes is a risk factor for heart failure and cardiovascular mortality with specific changes to myocardial metabolism, energetics, structure, and function. The gradual impairment of insulin production and signalling in diabetes is associated with elevated plasma fatty acids and increased myocardial free fatty acid uptake and activation of the transcription factor PPARα. The increased free fatty acid uptake results in accumulation of toxic metabolites, such as ceramide and diacylglycerol, activation of protein kinase C, and elevation of uncoupling protein-3. Insulin signalling and glucose uptake/oxidation become further impaired, and mitochondrial function and ATP production become compromised. Increased oxidative stress also impairs mitochondrial function and disrupts metabolic pathways. The diabetic heart relies on free fatty acids (FFA) as the major substrate for oxidative phosphorylation and is unable to increase glucose oxidation during ischaemia or hypoxia, thereby increasing myocardial injury, especially in ageing female diabetic animals. Pharmacological activation of PPARγ in adipose tissue may lower plasma FFA and improve recovery from myocardial ischaemic injury in diabetes. Not only is the diabetic heart energetically-impaired, it also has early diastolic dysfunction and concentric remodelling. The contractile function of the diabetic myocardium negatively correlates with epicardial adipose tissue, which secretes proinflammatory cytokines, resulting in interstitial fibrosis. Novel pharmacological strategies targeting oxidative stress seem promising in preventing progression of diabetic cardiomyopathy, although clinical evidence is lacking. Metabolic agents that lower plasma FFA or glucose, including PPARγ agonism and SGLT2 inhibition, may therefore be promising options.
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Affiliation(s)
- Cher-Rin Chong
- 1 Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Kieran Clarke
- 1 Department of Physiology, Anatomy and Genetics, University of Oxford
| | - Eylem Levelt
- 2 Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital
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Zhu L, Almaça J, Dadi PK, Hong H, Sakamoto W, Rossi M, Lee RJ, Vierra NC, Lu H, Cui Y, McMillin SM, Perry NA, Gurevich VV, Lee A, Kuo B, Leapman RD, Matschinsky FM, Doliba NM, Urs NM, Caron MG, Jacobson DA, Caicedo A, Wess J. β-arrestin-2 is an essential regulator of pancreatic β-cell function under physiological and pathophysiological conditions. Nat Commun 2017; 8:14295. [PMID: 28145434 PMCID: PMC5296650 DOI: 10.1038/ncomms14295] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Accepted: 12/15/2016] [Indexed: 01/06/2023] Open
Abstract
β-arrestins are critical signalling molecules that regulate many fundamental physiological functions including the maintenance of euglycemia and peripheral insulin sensitivity. Here we show that inactivation of the β-arrestin-2 gene, barr2, in β-cells of adult mice greatly impairs insulin release and glucose tolerance in mice fed with a calorie-rich diet. Both glucose and KCl-induced insulin secretion and calcium responses were profoundly reduced in β-arrestin-2 (barr2) deficient β-cells. In human β-cells, barr2 knockdown abolished glucose-induced insulin secretion. We also show that the presence of barr2 is essential for proper CAMKII function in β-cells. Importantly, overexpression of barr2 in β-cells greatly ameliorates the metabolic deficits displayed by mice consuming a high-fat diet. Thus, our data identify barr2 as an important regulator of β-cell function, which may serve as a new target to improve β-cell function. Beta-arrestins have key roles in development and metabolic functions as euglycaemic control and insulin sentitivity. Here Zhu et al. show that beta-arrestin-2 regulates insulin secretion and glucose tolerance in mice by promoting CAMKII functions in beta cells.
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Affiliation(s)
- Lu Zhu
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Joana Almaça
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Hao Hong
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA.,Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210023, China
| | - Wataru Sakamoto
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Mario Rossi
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Regina J Lee
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Huiyan Lu
- Mouse Transgenic Core Facility, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Yinghong Cui
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Sara M McMillin
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
| | - Nicole A Perry
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242, USA
| | - Bryan Kuo
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, Bethesda, Maryland 20892, USA
| | - Richard D Leapman
- Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, Bethesda, Maryland 20892, USA
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennslvania 19104, USA
| | - Nicolai M Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennslvania 19104, USA
| | - Nikhil M Urs
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Marc G Caron
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232, USA
| | - Alejandro Caicedo
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33136, USA
| | - Jürgen Wess
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
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Gerencser AA, Mookerjee SA, Jastroch M, Brand MD. Positive Feedback Amplifies the Response of Mitochondrial Membrane Potential to Glucose Concentration in Clonal Pancreatic Beta Cells. Biochim Biophys Acta Mol Basis Dis 2016; 1863:1054-1065. [PMID: 27771512 DOI: 10.1016/j.bbadis.2016.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 10/16/2016] [Accepted: 10/18/2016] [Indexed: 02/07/2023]
Abstract
Analysis of the cellular mechanisms of metabolic disorders, including type 2 diabetes mellitus, is complicated by the large number of reactions and interactions in metabolic networks. Metabolic control analysis with appropriate modularization is a powerful method for simplifying and analyzing these networks. To analyze control of cellular energy metabolism in adherent cell cultures of the INS-1 832/13 pancreatic β-cell model we adapted our microscopy assay of absolute mitochondrial membrane potential (ΔψM) to a fluorescence microplate reader format, and applied it in conjunction with cell respirometry. In these cells the sensitive response of ΔψM to extracellular glucose concentration drives glucose-stimulated insulin secretion. Using metabolic control analysis we identified the control properties that generate this sensitive response. Force-flux relationships between ΔψM and respiration were used to calculate kinetic responses to ΔψM of processes both upstream (glucose oxidation) and downstream (proton leak and ATP turnover) of ΔψM. The analysis revealed that glucose-evoked ΔψM hyperpolarization is amplified by increased glucose oxidation activity caused by factors downstream of ΔψM. At high glucose, the hyperpolarized ΔψM is stabilized almost completely by the action of glucose oxidation, whereas proton leak also contributes to the homeostatic control of ΔψM at low glucose. These findings suggest a strong positive feedback loop in the regulation of β-cell energetics, and a possible regulatory role of proton leak in the fasting state. Analysis of islet bioenergetics from published cases of type 2 diabetes suggests that disruption of this feedback can explain the damaged bioenergetic response of β-cells to glucose. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States; Image Analyst Software, 43 Nova Lane, Novato, CA 94945, United States.
| | - Shona A Mookerjee
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States; Touro University California College of Pharmacy, 1310 Club Drive, Vallejo, CA 94592, United States
| | - Martin Jastroch
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States
| | - Martin D Brand
- Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, United States
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Wortham M, Sander M. Mechanisms of β-cell functional adaptation to changes in workload. Diabetes Obes Metab 2016; 18 Suppl 1:78-86. [PMID: 27615135 PMCID: PMC5021190 DOI: 10.1111/dom.12729] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/09/2016] [Indexed: 11/28/2022]
Abstract
Insulin secretion must be tightly coupled to nutritional state to maintain blood glucose homeostasis. To this end, pancreatic β-cells sense and respond to changes in metabolic conditions, thereby anticipating insulin demands for a given physiological context. This is achieved in part through adjustments of nutrient metabolism, which is controlled at several levels including allosteric regulation, post-translational modifications, and altered expression of metabolic enzymes. In this review, we discuss mechanisms of β-cell metabolic and functional adaptation in the context of two physiological states that alter glucose-stimulated insulin secretion: fasting and insulin resistance. We review current knowledge of metabolic changes that occur in the β-cell during adaptation and specifically discuss transcriptional mechanisms that underlie β-cell adaptation. A more comprehensive understanding of how β-cells adapt to changes in nutrient state could identify mechanisms to be co-opted for therapeutically modulating insulin secretion in metabolic disease.
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Affiliation(s)
- M Wortham
- Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California San Diego, La Jolla
| | - M Sander
- Departments of Pediatrics and Cellular and Molecular Medicine, Pediatric Diabetes Research Center, University of California San Diego, La Jolla.
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44
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Gerencser AA, Mookerjee SA, Jastroch M, Brand MD. Measurement of the Absolute Magnitude and Time Courses of Mitochondrial Membrane Potential in Primary and Clonal Pancreatic Beta-Cells. PLoS One 2016; 11:e0159199. [PMID: 27404273 PMCID: PMC4942067 DOI: 10.1371/journal.pone.0159199] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/28/2016] [Indexed: 12/22/2022] Open
Abstract
The aim of this study was to simplify, improve and validate quantitative measurement of the mitochondrial membrane potential (ΔψM) in pancreatic β-cells. This built on our previously introduced calculation of the absolute magnitude of ΔψM in intact cells, using time-lapse imaging of the non-quench mode fluorescence of tetramethylrhodamine methyl ester and a bis-oxonol plasma membrane potential (ΔψP) indicator. ΔψM is a central mediator of glucose-stimulated insulin secretion in pancreatic β-cells. ΔψM is at the crossroads of cellular energy production and demand, therefore precise assay of its magnitude is a valuable tool to study how these processes interplay in insulin secretion. Dispersed islet cell cultures allowed cell type-specific, single-cell observations of cell-to-cell heterogeneity of ΔψM and ΔψP. Glucose addition caused hyperpolarization of ΔψM and depolarization of ΔψP. The hyperpolarization was a monophasic step increase, even in cells where the ΔψP depolarization was biphasic. The biphasic response of ΔψP was associated with a larger hyperpolarization of ΔψM than the monophasic response. Analysis of the relationships between ΔψP and ΔψM revealed that primary dispersed β-cells responded to glucose heterogeneously, driven by variable activation of energy metabolism. Sensitivity analysis of the calibration was consistent with β-cells having substantial cell-to-cell variations in amounts of mitochondria, and this was predicted not to impair the accuracy of determinations of relative changes in ΔψM and ΔψP. Finally, we demonstrate a significant problem with using an alternative ΔψM probe, rhodamine 123. In glucose-stimulated and oligomycin-inhibited β-cells the principles of the rhodamine 123 assay were breached, resulting in misleading conclusions.
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Affiliation(s)
- Akos A. Gerencser
- Buck Institute for Research on Aging, Novato, California, United States of America
- Image Analyst Software, Novato, California, United States of America
| | - Shona A. Mookerjee
- Buck Institute for Research on Aging, Novato, California, United States of America
- Touro University California College of Pharmacy, Vallejo, California, United States of America
| | - Martin Jastroch
- Buck Institute for Research on Aging, Novato, California, United States of America
| | - Martin D. Brand
- Buck Institute for Research on Aging, Novato, California, United States of America
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45
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Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis. PLoS One 2016; 11:e0152869. [PMID: 27138453 PMCID: PMC4854486 DOI: 10.1371/journal.pone.0152869] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/21/2016] [Indexed: 12/17/2022] Open
Abstract
Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger pathway interactions will improve understanding of critical regulatory sites, how different GPCRs interact and pharmacological targets for modulating insulin secretion in type 2 diabetes.
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Peiris H, Duffield MD, Fadista J, Jessup CF, Kashmir V, Genders AJ, McGee SL, Martin AM, Saiedi M, Morton N, Carter R, Cousin MA, Kokotos AC, Oskolkov N, Volkov P, Hough TA, Fisher EMC, Tybulewicz VLJ, Busciglio J, Coskun PE, Becker A, Belichenko PV, Mobley WC, Ryan MT, Chan JY, Laybutt DR, Coates PT, Yang S, Ling C, Groop L, Pritchard MA, Keating DJ. A Syntenic Cross Species Aneuploidy Genetic Screen Links RCAN1 Expression to β-Cell Mitochondrial Dysfunction in Type 2 Diabetes. PLoS Genet 2016; 12:e1006033. [PMID: 27195491 PMCID: PMC4873152 DOI: 10.1371/journal.pgen.1006033] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 04/18/2016] [Indexed: 12/20/2022] Open
Abstract
Type 2 diabetes (T2D) is a complex metabolic disease associated with obesity, insulin resistance and hypoinsulinemia due to pancreatic β-cell dysfunction. Reduced mitochondrial function is thought to be central to β-cell dysfunction. Mitochondrial dysfunction and reduced insulin secretion are also observed in β-cells of humans with the most common human genetic disorder, Down syndrome (DS, Trisomy 21). To identify regions of chromosome 21 that may be associated with perturbed glucose homeostasis we profiled the glycaemic status of different DS mouse models. The Ts65Dn and Dp16 DS mouse lines were hyperglycemic, while Tc1 and Ts1Rhr mice were not, providing us with a region of chromosome 21 containing genes that cause hyperglycemia. We then examined whether any of these genes were upregulated in a set of ~5,000 gene expression changes we had identified in a large gene expression analysis of human T2D β-cells. This approach produced a single gene, RCAN1, as a candidate gene linking hyperglycemia and functional changes in T2D β-cells. Further investigations demonstrated that RCAN1 methylation is reduced in human T2D islets at multiple sites, correlating with increased expression. RCAN1 protein expression was also increased in db/db mouse islets and in human and mouse islets exposed to high glucose. Mice overexpressing RCAN1 had reduced in vivo glucose-stimulated insulin secretion and their β-cells displayed mitochondrial dysfunction including hyperpolarised membrane potential, reduced oxidative phosphorylation and low ATP production. This lack of β-cell ATP had functional consequences by negatively affecting both glucose-stimulated membrane depolarisation and ATP-dependent insulin granule exocytosis. Thus, from amongst the myriad of gene expression changes occurring in T2D β-cells where we had little knowledge of which changes cause β-cell dysfunction, we applied a trisomy 21 screening approach which linked RCAN1 to β-cell mitochondrial dysfunction in T2D.
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Affiliation(s)
- Heshan Peiris
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Michael D. Duffield
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | | | - Claire F. Jessup
- Islet Biology Laboratory, Department of Anatomy and Histology and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
- Discipline of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Vinder Kashmir
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Amanda J. Genders
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
| | - Sean L. McGee
- Metabolic Remodelling Laboratory, Metabolic Research Unit, School of Medicine, Deakin University, Geelong, Australia
- Metabolism and Inflammation Program, Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Alyce M. Martin
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Madiha Saiedi
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
| | - Nicholas Morton
- Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Roderick Carter
- Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Michael A. Cousin
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Alexandros C. Kokotos
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Petr Volkov
- Lund University Diabetes Centre, Malmö, Sweden
| | - Tertius A. Hough
- Mary Lyon Centre Pathology, MRC Harwell, Harwell Oxford Science Park, Oxford, United Kingdom
| | - Elizabeth M. C. Fisher
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London, United Kingdom
| | - Victor L. J. Tybulewicz
- Francis Crick Institute, Mill Hill, London, United Kingdom
- Department of Medicine, Imperial College London, London, United Kingdom
| | - Jorge Busciglio
- Department of Neurobiology and Behaviour, University of California, Irvine, Irvine, California, United States of America
| | - Pinar E. Coskun
- Department of Neurobiology and Behaviour, University of California, Irvine, Irvine, California, United States of America
| | - Ann Becker
- Department of Neurosciences School of Medicine, University of California, San Diego, San Diego, California, United States of America
| | - Pavel V. Belichenko
- Department of Neurosciences School of Medicine, University of California, San Diego, San Diego, California, United States of America
| | - William C. Mobley
- Department of Neurosciences School of Medicine, University of California, San Diego, San Diego, California, United States of America
| | - Michael T. Ryan
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Jeng Yie Chan
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales, Australia
| | - D. Ross Laybutt
- Diabetes and Metabolism Division, Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales, Australia
| | - P. Toby Coates
- Clinical and Experimental Transplantation Group, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, Australia
| | - Sijun Yang
- Animal Experiment Center, Animal Biosafety Level-III Laboratory, Wuhan University, Wuhan, China
| | | | - Leif Groop
- Lund University Diabetes Centre, Malmö, Sweden
| | - Melanie A. Pritchard
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Damien J. Keating
- Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia
- South Australian Health and Medical Research Institute, Adelaide, Australia
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Doliba NM, Liu Q, Li C, Chen J, Chen P, Liu C, Frederick DW, Baur JA, Bennett MJ, Naji A, Matschinsky FM. Accumulation of 3-hydroxytetradecenoic acid: Cause or corollary of glucolipotoxic impairment of pancreatic β-cell bioenergetics? Mol Metab 2015; 4:926-39. [PMID: 26909309 PMCID: PMC4731732 DOI: 10.1016/j.molmet.2015.09.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 09/16/2015] [Accepted: 09/25/2015] [Indexed: 12/20/2022] Open
Abstract
Objectives Hyperglycemia and elevated blood lipids are the presumed precipitating causes of β-cell damage in T2DM as the result of a process termed “glucolipotoxicity”. Here, we tested whether glucolipotoxic pathophysiology is caused by defective bioenergetics using islets in culture. Methods Insulin secretion, respiration, ATP generation, fatty acid (FA) metabolite profiles and gene expression were determined in isolated islets treated under glucolipotoxic culture conditions. Results Over time, chronic exposure of mouse islets to FAs with glucose leads to bioenergetic failure and reduced insulin secretion upon stimulation with glucose or amino acids. Islets exposed to glucolipotoxic conditions displayed biphasic changes of the oxygen consumption rate (OCR): an initial increase in baseline and Vmax of OCR after 3 days, followed by decreased baseline and glucose stimulated OCR after 5 days. These changes were associated with lower islet ATP levels, impaired glucose-induced ATP generation, a trend for reduced mitochondrial DNA content and reduced expression of mitochondrial transcription factor A (Tfam). We discovered the accumulation of carnitine esters of hydroxylated long chain FAs, in particular 3-hydroxytetradecenoyl-carnitine. Conclusions As long chain 3-hydroxylated FA metabolites are known to uncouple heart and brain mitochondria [53], [54], [55], we propose that under glucolipotoxic condition, unsaturated hydroxylated long-chain FAs accumulate, uncouple and ultimately inhibit β-cell respiration. This leads to the slow deterioration of mitochondrial function progressing to bioenergetics β-cell failure. We found low capacity of islets to generate ATP after glucolipotoxic treatment. Found biphasic (up/down) respiratory time course as expression of glucolipotoxicity. We found β-Hydroxylated long FA metabolites as new glucolipotoxicity mediators. β-Hydroxylated long FAs are known to uncouple Ox/Phos. We propose defective bioenergetics as main cause of glucolipotoxicity.
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Affiliation(s)
- Nicolai M. Doliba
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
- Corresponding author. University of Pennsylvania, Biochemistry/Biophysics, 3400 Civic Center Blvd, Smilow Center for Translation Research, TRC12-131, Philadelphia, PA 19104, United States. Tel.: +1 215 898 4366; fax: +1 215 898 5408.
| | - Qing Liu
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Changhong Li
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Jie Chen
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Pan Chen
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Chengyang Liu
- Department of Surgery, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - David W. Frederick
- Department of Physiology, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Joseph A. Baur
- Department of Physiology, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Michael J. Bennett
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Ali Naji
- Department of Surgery, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
| | - Franz M. Matschinsky
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, United States
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania School of Medicine, United States
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Roma LP, Duprez J, Jonas JC. Glucokinase activation is beneficial or toxic to cultured rat pancreatic islets depending on the prevailing glucose concentration. Am J Physiol Endocrinol Metab 2015; 309:E632-9. [PMID: 26264555 DOI: 10.1152/ajpendo.00154.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 08/10/2015] [Indexed: 11/22/2022]
Abstract
In rat pancreatic islets, β-cell gene expression, survival, and subsequent acute glucose stimulation of insulin secretion (GSIS) are optimally preserved by prolonged culture at 10 mM glucose (G10) and markedly altered by culture at G5 or G30. Here, we tested whether pharmacological glucokinase (GK) activation prevents these alterations during culture or improves GSIS after culture. Rat pancreatic islets were cultured 1-7 days at G5, G10, or G30 with or without 3 μM of the GK activator Ro 28-0450 (Ro). After culture, β-cell apoptosis and islet gene mRNA levels were measured, and the acute glucose-induced increase in NAD(P)H autofluorescence, intracellular calcium concentration, and insulin secretion were tested in the absence or presence of Ro. Prolonged culture of rat islets at G5 or G30 instead of G10 triggered β-cell apoptosis and reduced their glucose responsiveness. Addition of Ro during culture differently affected β-cell survival and glucose responsiveness depending on the glucose concentration during culture: it was beneficial to β-cell survival and function at G5, detrimental at G10, and ineffective at G30. In contrast, acute GK activation with Ro increased the glucose sensitivity of islets cultured at G10 but failed at restoring β-cell glucose responsiveness after culture at G5 or G30. We conclude that pharmacological GK activation prevents the alteration of β-cell survival and function by long-term culture at G5 but mimics glucotoxicity when added to G10. The complex effects of glucose on the β-cell phenotype result from changes in glucose metabolism and not from an effect of glucose per se.
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Affiliation(s)
- Leticia P Roma
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium; and
| | - Jessica Duprez
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium; and
| | - Jean-Christophe Jonas
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium; and Fonds de la recherche scientifique-FNRS, Brussels, Belgium
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Henquin JC, Dufrane D, Kerr-Conte J, Nenquin M. Dynamics of glucose-induced insulin secretion in normal human islets. Am J Physiol Endocrinol Metab 2015; 309:E640-50. [PMID: 26264556 DOI: 10.1152/ajpendo.00251.2015] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 08/10/2015] [Indexed: 11/22/2022]
Abstract
The biphasic pattern of glucose-induced insulin secretion is altered in type 2 diabetes. Impairment of the first phase is an early sign of β-cell dysfunction, but the underlying mechanisms are still unknown. Their identification through in vitro comparisons of islets from diabetic and control subjects requires characterization and quantification of the dynamics of insulin secretion by normal islets. When perifused normal human islets were stimulated with 15 mmol/l glucose (G15), the proinsulin/insulin ratio in secretory products rapidly and reversibly decreased (∼50%) and did not reaugment with time. Switching from prestimulatory G3 to G6-G30 induced biphasic insulin secretion with flat but sustained (2 h) second phases. Stimulation index reached 6.7- and 3.6-fold for the first and second phases induced by G10. Concentration dependency was similar for both phases, with half-maximal and maximal responses at G6.5 and G15, respectively. First-phase response to G15-G30 was diminished by short (30-60 min) prestimulation in G6 (vs. G3) and abolished by prestimulation in G8, whereas the second phase was unaffected. After 1-2 days of culture in G8 (instead of G5), islets were virtually unresponsive to G15. In both settings, a brief return to G3-G5 or transient omission of CaCl2 restored biphasic insulin secretion. Strikingly, tolbutamide and arginine evoked immediate insulin secretion in islets refractory to glucose. In conclusion, we quantitatively characterized the dynamics of glucose-induced insulin secretion in normal human islets and showed that slight elevation of prestimulatory glucose reversibly impairs the first phase, which supports the view that the similar impairment in type 2 diabetic patients might partially be a secondary phenomenon.
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Affiliation(s)
- Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium;
| | - Denis Dufrane
- Endocrine Cell Therapy Unit, University Clinics Saint-Luc, University of Louvain, Brussels, Belgium
| | - Julie Kerr-Conte
- Institut National de la Santé et de la Recherche Médicale U1190, Translational Research for Diabetes, and European Genomic Institute for Diabetes, University of Lille, Lille, France
| | - Myriam Nenquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain, Brussels, Belgium
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Gerencser AA. Bioenergetic Analysis of Single Pancreatic β-Cells Indicates an Impaired Metabolic Signature in Type 2 Diabetic Subjects. Endocrinology 2015. [PMID: 26204464 DOI: 10.1210/en.2015-1552] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Impaired activation of mitochondrial energy metabolism by glucose has been demonstrated in type 2 diabetic β-cells. The cause of this dysfunction is unknown. The aim of this study was to identify segments of energy metabolism with normal or with altered function in human type 2 diabetes mellitus. The mitochondrial membrane potential (ΔψM), and its response to glucose, is the main driver of mitochondrial ATP synthesis and is hence a central mediator of glucose-induced insulin secretion, but its quantitative determination in β-cells from human donors has not been attempted, due to limitations in assay technology. Here, novel fluorescence microscopic assays are exploited to quantify ΔψM and its response to glucose and other secretagogues in β-cells of dispersed pancreatic islet cells from 4 normal and 3 type 2 diabetic organ donors. Mitochondrial volume densities and the magnitude of ΔψM in low glucose were not consistently altered in diabetic β-cells. However, ΔψM was consistently less responsive to elevation of glucose concentration, whereas the decreased response was not observed with metabolizable secretagogue mixtures that feed directly into the tricarboxylic acid cycle. Single-cell analysis of the heterogeneous responses to metabolizable secretagogues indicated no dysfunction in relaying ΔψM hyperpolarization to plasma membrane potential depolarization in diabetic β-cells. ΔψM of diabetic β-cells was distinctly responsive to acute inhibition of ATP synthesis during glucose stimulation. It is concluded that the mechanistic deficit in glucose-induced insulin secretion and mitochondrial hyperpolarization of diabetic human β-cells is located upstream of the tricarboxylic acid cycle and manifests in dampening the control of ΔψM by glucose metabolism.
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Affiliation(s)
- Akos A Gerencser
- Buck Institute for Research on Aging and Image Analyst Software, Novato, California 94945; and College of Pharmacy, Touro University California, Vallejo, California 94592
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