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Cordiner RLM, Bedair K, Mari A, Pearson E. Low-Dose Sulfonylurea Plus DPP4 Inhibitor Lower Blood Glucose and Enhance Beta-Cell Function Without Hypoglycemia. J Clin Endocrinol Metab 2024; 109:2106-2115. [PMID: 38267622 PMCID: PMC11244179 DOI: 10.1210/clinem/dgae033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 12/14/2023] [Accepted: 01/23/2024] [Indexed: 01/26/2024]
Abstract
CONTEXT Low-dose sulfonylureas (SUs) have been found to augment the classical incretin effect, increase glucose sensitivity and late phase incretin potentiation. OBJECTIVE To evaluate potential synergy between low-dose SU plus a dipeptidyl peptidase 4 (DPP4) inhibitor. METHODS Unblinded randomized crossover study at the Clinical Research Centre, University of Dundee. Thirty participants with T2DM (HbA1c < 64 mmol/mol) were treated with diet or metformin. Participants completed 4, 14-day blocks in a random order: control, gliclazide 20 mg (SU), sitagliptin 100 mg (DPP4 inhibitor [DPP4i]), or combination (SUDPP4i). A mixed meal test was conducted after each intervention. The primary outcome was the effect of treatment on beta-cell glucose sensitivity. Secondary outcomes included frequency of glucose <3 mmol/L on continuous glucose monitoring, subanalyses by genotype (KNCJ11 E23K), gender, and body mass index. RESULTS SU combination with DPP4i showed additive effect on glucose lowering: mean glucose area under the curve (mean 95% CI) (mmol/L) was control 11.5 (10.7-12.3), DPP4i 10.2 (9.4-11.1), SU 9.7 (8.9-10.5), SUDPP4i 8.7 (7.9-9.5) (P < .001). Glucose sensitivity mirrored the additive effect (pmol min-1 m-2 mM-1): control 71.5 (51.1-91.9), DPP4i 75.9 (55.7-96.0), SU 86.3 (66.1-106.4), SUDPP4i 94.1 (73.9-114.3) (P = .04). The additive effect was seen in men but not women. Glucose time in range <3 mmol/L on continuous glucose monitoring (%) was unaffected: control 1 (2-4), DPP4i 2 (3-6), SU 1 (0-4), SUDPP4i 3 (2-7) (P = .65). CONCLUSION Low-dose sulfonylurea plus DPP4i has a potent glucose-lowering effect through augmentation of beta-cell function. A double-blind randomized controlled trial would formalize efficacy and safety of this combination, which may avoid negative aspects of SU.
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Affiliation(s)
- Ruth L M Cordiner
- Division of Population, Health and Genomics, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Khaled Bedair
- Division of Population, Health and Genomics, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - Andrea Mari
- National Research Council, Institute of Neuroscience, University of Padua, 35127 Padua, Italy
| | - Ewan Pearson
- Division of Population, Health and Genomics, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
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Ogata H, Kitamura S, Fujiwara M, Shimizu M, Tan C, Zhao S, Maejima Y, Shimomura K. Dose Dependent Effect of Sulfamethoxazole on Inhibiting K ATP Channel of Mouse Pancreatic β Cell. Dose Response 2023; 21:15593258231203611. [PMID: 37780606 PMCID: PMC10540586 DOI: 10.1177/15593258231203611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 09/08/2023] [Indexed: 10/03/2023] Open
Abstract
Sulfamethoxazole (SMX) is widely used as an antibiotic in the clinical application with side effects of hypoglycemia. This is because SMX contains the sulfonamide structure, which closes ATP-sensitive potassium (KATP) channels and induces insulin secretion. However, there are no detail reports that measure the effective dose that can close KATP channels and induce insulin secretion. In this study, whole-cell patch clamp recording was utilized to measure the effect of SMX on KATP channel activity on pancreatic β cells. Also, the static incubation assay with mice islets was assessed to measure the insulin secretion capacity of SMX. SMX was shown to inhibit the KATP channel in pancreatic β cell membrane and induce insulin secretion in relatively high concentration. The half maximal inhibitory concentration (IC50) for KATP channel activity of SMX was .46 ± .08 mM. It was also shown that a near IC50 concentration of SMX (.5 mM) was able to nearly fully block the KATP channel when simultaneously applied with low concentration sulfonylurea, tolbutamide (.01 mM). Our present data provide important information for the clinical use of SMX to treat infection in diabetic patients using sulfonylureas.
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Affiliation(s)
- Hiroshi Ogata
- Department of Bioregulation and Pharmacological Medicine, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Shigeki Kitamura
- Department of Bioregulation and Pharmacological Medicine, School of Medicine, Fukushima Medical University, Fukushima, Japan
- Department of Plastic and Reconstructive Surgery, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Makoto Fujiwara
- Department of Bioregulation and Pharmacological Medicine, School of Medicine, Fukushima Medical University, Fukushima, Japan
- Department of Diabetes, Endocrinology and Metabolism, Tsukuba Medical Center, Ibaragi, Japan
| | - Masaru Shimizu
- Department of Bioregulation and Pharmacological Medicine, School of Medicine, Fukushima Medical University, Fukushima, Japan
- Department of Neurology, Matsumura General Hospital, Fukushima, Japan
| | - Chengbo Tan
- Advanced Clinical Research Center, Fukushima Global Medical Science Center, Fukushima Medical University, Fukushima, Japan
| | - Songji Zhao
- Advanced Clinical Research Center, Fukushima Global Medical Science Center, Fukushima Medical University, Fukushima, Japan
| | - Yuko Maejima
- Department of Bioregulation and Pharmacological Medicine, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Kenju Shimomura
- Department of Bioregulation and Pharmacological Medicine, School of Medicine, Fukushima Medical University, Fukushima, Japan
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3
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Ashcroft FM. KATP Channels and the Metabolic Regulation of Insulin Secretion in Health and Disease: The 2022 Banting Medal for Scientific Achievement Award Lecture. Diabetes 2023; 72:693-702. [PMID: 37815796 PMCID: PMC10202764 DOI: 10.2337/dbi22-0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 02/28/2023] [Indexed: 10/11/2023]
Abstract
Diabetes is characterized by elevation of plasma glucose due to an insufficiency of the hormone insulin and is associated with both inadequate insulin secretion and impaired insulin action. The Banting Medal for Scientific Achievement Commemorates the work of Sir Frederick Banting, a member of the team that first used insulin to treat a patient with diabetes almost exactly one hundred years ago on 11 January 1922. This article is based on my Banting lecture of 2022 and concerns the mechanism of glucose-stimulated insulin secretion from pancreatic β-cells, with an emphasis on the metabolic regulation of the KATP channel. This channel plays a central role in insulin release. Its closure in response to metabolically generated changes in the intracellular concentrations of ATP and MgADP stimulates β-cell electrical activity and insulin granule exocytosis. Activating mutations in KATP channel genes that impair the ability of the channel to respond to ATP give rise to neonatal diabetes. Impaired KATP channel regulation may also play a role in type 2 diabetes. I conjecture that KATP channel closure in response to glucose is reduced because of impaired glucose metabolism, which fails to generate a sufficient increase in ATP. Consequently, glucose-stimulated β-cell electrical activity is less. As ATP is also required for insulin granule exocytosis, both reduced exocytosis and less β-cell electrical activity may contribute to the reduction in insulin secretion. I emphasize that what follows is not a definitive review of the topic but a personal account of the contribution of my team to the field that is based on my Banting lecture.
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Affiliation(s)
- Frances M. Ashcroft
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, U.K
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4
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Choi J, Shin E, Lee J, Devarasou S, Kim D, Shin JH, Choi JH, Heo WD, Han YM. Light-stimulated insulin secretion from pancreatic islet-like organoids derived from human pluripotent stem cells. Mol Ther 2023; 31:1480-1495. [PMID: 36932674 PMCID: PMC10188912 DOI: 10.1016/j.ymthe.2023.03.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 02/06/2023] [Accepted: 03/12/2023] [Indexed: 03/18/2023] Open
Abstract
Optogenetic techniques permit non-invasive, spatiotemporal, and reversible modulation of cellular activities. Here, we report a novel optogenetic regulatory system for insulin secretion in human pluripotent stem cell (hPSC)-derived pancreatic islet-like organoids using monSTIM1 (monster-opto-Stromal interaction molecule 1), an ultra-light-sensitive OptoSTIM1 variant. The monSTIM1 transgene was incorporated at the AAVS1 locus in human embryonic stem cells (hESCs) by CRISPR-Cas9-mediated genome editing. Not only were we able to elicit light-induced intracellular Ca2+ concentration ([Ca2+]i) transients from the resulting homozygous monSTIM1+/+-hESCs, but we also successfully differentiated them into pancreatic islet-like organoids (PIOs). Upon light stimulation, the β-cells in these monSTIM1+/+-PIOs displayed reversible and reproducible [Ca2+]i transient dynamics. Furthermore, in response to photoexcitation, they secreted human insulin. Light-responsive insulin secretion was similarly observed in monSTIM1+/+-PIOs produced from neonatal diabetes (ND) patient-derived induced pluripotent stem cells (iPSCs). Under LED illumination, monSTIM1+/+-PIO-transplanted diabetic mice produced human c-peptide. Collectively, we developed a cellular model for the optogenetic control of insulin secretion using hPSCs, with the potential to be applied to the amelioration of hyperglycemic disorders.
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Affiliation(s)
- Jieun Choi
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Eunji Shin
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Jinsu Lee
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | | | - Dongkyu Kim
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea
| | - Jennifer H Shin
- Department of Mechanical Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Jin-Ho Choi
- Department of Pediatrics, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea
| | - Won Do Heo
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea.
| | - Yong-Mahn Han
- Department of Biological Sciences, KAIST, Daejeon 34141, Republic of Korea; Graduate School of Medical Science and Engineering, KAIST, Daejeon 34141, Republic of Korea.
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5
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Abstract
Plasma glucose is tightly regulated via the secretion of the two glucose-regulating hormones insulin and glucagon. Situated next to the insulin-secreting β-cells, the α-cells produce and secrete glucagon-one of the body's few blood glucose-increasing hormones. Diabetes is a bihormonal disorder, resulting from both inadequate insulin secretion and dysregulation of glucagon. The year 2023 marks the 100th anniversary of the discovery of glucagon, making it particularly timely to highlight the roles of this systemic metabolic messenger in health and disease.
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Affiliation(s)
- Patrick E MacDonald
- Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
- Metabolic Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Gothenburg, Sweden.
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Abstract
Ubiquitously expressed throughout the body, ATP-sensitive potassium (KATP) channels couple cellular metabolism to electrical activity in multiple tissues; their unique assembly as four Kir6 pore-forming subunits and four sulfonylurea receptor (SUR) subunits has resulted in a large armory of selective channel opener and inhibitor drugs. The spectrum of monogenic pathologies that result from gain- or loss-of-function mutations in these channels, and the potential for therapeutic correction of these pathologies, is now clear. However, while available drugs can be effective treatments for specific pathologies, cross-reactivity with the other Kir6 or SUR subfamily members can result in drug-induced versions of each pathology and may limit therapeutic usefulness. This review discusses the background to KATP channel physiology, pathology, and pharmacology and considers the potential for more specific or effective therapeutic agents.
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Affiliation(s)
- Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases and Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA;
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7
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Driggers CM, Shyng SL. Mechanistic insights on KATP channel regulation from cryo-EM structures. J Gen Physiol 2022; 155:213723. [PMID: 36441147 PMCID: PMC9700523 DOI: 10.1085/jgp.202113046] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/19/2022] [Accepted: 11/08/2022] [Indexed: 11/29/2022] Open
Abstract
Gated by intracellular ATP and ADP, ATP-sensitive potassium (KATP) channels couple cell energetics with membrane excitability in many cell types, enabling them to control a wide range of physiological processes based on metabolic demands. The KATP channel is a complex of four potassium channel subunits from the Kir channel family, Kir6.1 or Kir6.2, and four sulfonylurea receptor subunits, SUR1, SUR2A, or SUR2B, from the ATP-binding cassette (ABC) transporter family. Dysfunction of KATP channels underlies several human diseases. The importance of these channels in human health and disease has made them attractive drug targets. How the channel subunits interact with one another and how the ligands interact with the channel to regulate channel activity have been long-standing questions in the field. In the past 5 yr, a steady stream of high-resolution KATP channel structures has been published using single-particle cryo-electron microscopy (cryo-EM). Here, we review the advances these structures bring to our understanding of channel regulation by physiological and pharmacological ligands.
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Affiliation(s)
- Camden M. Driggers
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR
| | - Show-Ling Shyng
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health and Science University, Portland, OR,Correspondence to Show-Ling Shyng:
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8
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Ramu Y, Yamakaze J, Zhou Y, Hoshi T, Lu Z. Blocking Kir6.2 channels with SpTx1 potentiates glucose-stimulated insulin secretion from murine pancreatic β cells and lowers blood glucose in diabetic mice. eLife 2022; 11:77026. [PMID: 35212627 PMCID: PMC8880991 DOI: 10.7554/elife.77026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 01/26/2022] [Indexed: 11/16/2022] Open
Abstract
ATP-sensitive K+ (KATP) channels in pancreatic β cells are comprised of pore-forming subunits (Kir6.2) and modulatory sulfonylurea receptor subunits (SUR1). The ATP sensitivity of these channels enables them to couple metabolic state to insulin secretion in β cells. Antidiabetic sulfonylureas such as glibenclamide target SUR1 and indirectly suppress Kir6.2 activity. Glibenclamide acts as both a primary and a secondary secretagogue to trigger insulin secretion and potentiate glucose-stimulated insulin secretion, respectively. We tested whether blocking Kir6.2 itself causes the same effects as glibenclamide, and found that the Kir6.2 pore-blocking venom toxin SpTx1 acts as a strong secondary, but not a strong primary, secretagogue. SpTx1 triggered a transient rise of plasma insulin and lowered the elevated blood glucose of diabetic mice overexpressing Kir6.2 but did not affect those of nondiabetic mice. This proof-of-concept study suggests that blocking Kir6.2 may serve as an effective treatment for diabetes and other diseases stemming from KATP hyperactivity that cannot be adequately suppressed with sulfonylureas.
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Affiliation(s)
- Yajamana Ramu
- Department of Physiology, Perelman School of Medicine University of Pennsylvania, Philadelphia, United States
| | - Jayden Yamakaze
- Department of Physiology, Perelman School of Medicine University of Pennsylvania, Philadelphia, United States
| | - Yufeng Zhou
- Department of Physiology, Perelman School of Medicine University of Pennsylvania, Philadelphia, United States
| | - Toshinori Hoshi
- Department of Physiology, Perelman School of Medicine University of Pennsylvania, Philadelphia, United States
| | - Zhe Lu
- Department of Physiology, Perelman School of Medicine University of Pennsylvania, Philadelphia, United States
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9
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Abstract
Glycaemic response to metformin and sulphonylureas is heritable - with ~34%-37% of variation explainable by common genetic variation. The premise of this review is that by understanding how genetic variation contributes to drug response we can gain insights into the mechanisms of action of diabetes drugs. Here, I focus on two old drugs, metformin and sulphonylureas, where I would suggest we still have a lot to learn about their mechanism of action or their optimal use in clinical care. The fact that reduced function variants of the key transporter that takes metformin into the liver (OCT1) do not alter glycaemic response to metformin suggests that metformin does not need to get into the liver to work. A subsequent GWAS of metformin response identifies a robust variant that alters GLUT2 expression - which may support increasing evidence that metformin works primarily in the gut. For sulphonylureas, observation from patients with neonatal diabetes due to activating KATP channel mutations treated with sulphonylureas identified a novel role for sulphonylureas to enable β-cell incretin response. This work led to recent studies of low-dose sulphonylurea (20 mg gliclazide) in T2DM, which identified that at this dose sulphonylureas augment the incretin effect and increase β-cell glucose sensitivity, without increasing hypoglycaemia risk. This work, prompted by studies in monogenic diabetes, suggests that we have historically been using sulphonylureas at too high a dose. With increasing availability of genetic data pharmacogenomic studies in patients with diabetes should reveal mechanistic insights into old and new diabetes drugs, with the potential for optimized use and novel therapies.
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Affiliation(s)
- Ewan R Pearson
- Professor of Diabetic Medicine, Head of Division, Population Health & Genomics, School of Medicine, University of Dundee, Dundee, UK
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10
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Tang D, Xu J, Li Y, Zhao P, Kong X, Hu H, Liang S, Tang C, Liu Z. Molecular mechanisms of centipede toxin SsTx-4 inhibition of inwardly rectifying potassium channels. J Biol Chem 2021; 297:101076. [PMID: 34391777 PMCID: PMC8413892 DOI: 10.1016/j.jbc.2021.101076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/05/2021] [Accepted: 08/11/2021] [Indexed: 11/29/2022] Open
Abstract
Inwardly rectifying potassium channels (Kirs) are important drug targets, with antagonists for the Kir1.1, Kir4.1, and pancreatic Kir6.2/SUR1 channels being potential drug candidates for treating hypertension, depression, and diabetes, respectively. However, few peptide toxins acting on Kirs are identified and their interacting mechanisms remain largely elusive yet. Herein, we showed that the centipede toxin SsTx-4 potently inhibited the Kir1.1, Kir4.1, and Kir6.2/SUR1 channels with nanomolar to submicromolar affinities and intensively studied the molecular bases for toxin–channel interactions using patch-clamp analysis and site-directed mutations. Other Kirs including Kir2.1 to 2.4, Kir4.2, and Kir7.1 were resistant to SsTx-4 treatment. Moreover, SsTx-4 inhibited the inward and outward currents of Kirs with different potencies, possibly caused by a K+ “knock-off” effect, suggesting the toxin functions as an out pore blocker physically occluding the K+-conducting pathway. This conclusion was further supported by a mutation analysis showing that M137 located in the outer vestibule of the Kir6.2/ΔC26 channel was the key residue mediating interaction with SsTx-4. On the other hand, the molecular determinants within SsTx-4 for binding these Kir channels only partially overlapped, with K13 and F44 being the common key residues. Most importantly, K11A, P15A, and Y16A mutant toxins showed improved affinity and/or selectivity toward Kir6.2, while R12A mutant toxin had increased affinity for Kir4.1. To our knowledge, SsTx-4 is the first characterized peptide toxin with Kir4.1 inhibitory activity. This study provides useful insights for engineering a Kir6.2/SUR1 channel–specific antagonist based on the SsTx-4 template molecule and may be useful in developing new antidiabetic drugs.
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Affiliation(s)
- Dongfang Tang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China; College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, Hunan, China
| | - Jiahui Xu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Yinping Li
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Piao Zhao
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Xiangjin Kong
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Haoliang Hu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Songping Liang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China
| | - Cheng Tang
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
| | - Zhonghua Liu
- The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, China.
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Al-Saleh Y, Sabico S, Al-Furqani A, Jayyousi A, Alromaihi D, Ba-Essa E, Alawadi F, Alkaabi J, Hassanein M, Al-Sifri S, Saleh S, Alessa T, Al-Daghri NM. Sulfonylureas in the Current Practice of Type 2 Diabetes Management: Are They All the Same? Consensus from the Gulf Cooperation Council (GCC) Countries Advisory Board on Sulfonylureas. Diabetes Ther 2021; 12:2115-2132. [PMID: 33983614 PMCID: PMC8342668 DOI: 10.1007/s13300-021-01059-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/09/2021] [Indexed: 12/22/2022] Open
Abstract
Since their inception in the commercial market in the mid-twentieth century, sulfonylureas (SUs) have remained a therapeutic option in the management of type 2 diabetes (T2D). Despite their established glucose-lowering effects, there is no consensus among global experts and modern guidelines regarding the priority of SUs in relation to other therapeutic options, given the lack of evidence that SUs are associated with a low risk of macrovascular events and excess mortality. However, findings from recent trials and real-time observations have resolved this contentious issue somewhat, albeit to varying degrees. The present consensus discusses the role of SUs in contemporary diabetes management in the Gulf Cooperation Council (GCC) countries. Regional experts from these countries gathered virtually to formulate a consensus following presentations of topics relevant to SU therapy with an emphasis on gliclazide, including long-term efficacy, cost, end-organ benefits, and side effects, based on up-to-date evidence. The present narrative review reflects the conclusions of this assembly and provides a platform upon which future guidelines for the use of SUs in the GCC can be tailored.
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Affiliation(s)
- Yousef Al-Saleh
- College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, 22490, Saudi Arabia.
- King Abdullah International Medical Research Center, Riyadh, 11481, Saudi Arabia.
- Department of Medicine, King Abdulaziz Medical City, Riyadh, Ministry of National Guard-Health Affairs, Riyadh, 14611, Saudi Arabia.
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
| | - Shaun Sabico
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | | | - Amin Jayyousi
- Endocrine and Diabetes Section, Hamad Medical Corporation, Doha, Qatar
- Weill Cornell Medical College, Doha, Qatar
| | - Dalal Alromaihi
- King Hamad University Hospital, Busaiteen, Bahrain
- Medical University of Bahrain, Busaiteen, Bahrain
- Bahrain Diabetes Society, Manama, Bahrain
| | | | - Fatheya Alawadi
- Endocrine Department, Dubai Hospital, Dubai Health Authority, Dubai, United Arab Emirates
| | - Juma Alkaabi
- Department of Internal Medicine, College of Medicine, and Health Sciences, UAE University, Al Ain, United Arab Emirates
| | - Mohamed Hassanein
- Endocrine Department, Dubai Hospital, Dubai Health Authority, Dubai, United Arab Emirates
| | | | - Seham Saleh
- Prince Sultan Cardiac Center, Riyadh, Saudi Arabia
| | - Thamer Alessa
- Division of Endocrinology, Diabetes and Metabolism, Jaber Al-Ahmad Hospital, Kuwait City, Kuwait
- Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Nasser M Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
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12
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Stožer A, Paradiž Leitgeb E, Pohorec V, Dolenšek J, Križančić Bombek L, Gosak M, Skelin Klemen M. The Role of cAMP in Beta Cell Stimulus-Secretion and Intercellular Coupling. Cells 2021; 10:1658. [PMID: 34359828 PMCID: PMC8304079 DOI: 10.3390/cells10071658] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/18/2021] [Accepted: 06/28/2021] [Indexed: 12/22/2022] Open
Abstract
Pancreatic beta cells secrete insulin in response to stimulation with glucose and other nutrients, and impaired insulin secretion plays a central role in development of diabetes mellitus. Pharmacological management of diabetes includes various antidiabetic drugs, including incretins. The incretin hormones, glucagon-like peptide-1 and gastric inhibitory polypeptide, potentiate glucose-stimulated insulin secretion by binding to G protein-coupled receptors, resulting in stimulation of adenylate cyclase and production of the secondary messenger cAMP, which exerts its intracellular effects through activation of protein kinase A or the guanine nucleotide exchange protein 2A. The molecular mechanisms behind these two downstream signaling arms are still not fully elucidated and involve many steps in the stimulus-secretion coupling cascade, ranging from the proximal regulation of ion channel activity to the central Ca2+ signal and the most distal exocytosis. In addition to modifying intracellular coupling, the effect of cAMP on insulin secretion could also be at least partly explained by the impact on intercellular coupling. In this review, we systematically describe the possible roles of cAMP at these intra- and inter-cellular signaling nodes, keeping in mind the relevance for the whole organism and translation to humans.
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Affiliation(s)
- Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Lidija Križančić Bombek
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
- Faculty of Natural Sciences and Mathematics, University of Maribor, SI-2000 Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, SI-2000 Maribor, Slovenia; (A.S.); (E.P.L.); (V.P.); (J.D.); (L.K.B.); (M.G.)
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13
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Cao L, He Y, Huang Q, Zhang Y, Deng P, Du W, Hua Z, Zhu M, Wei H. Clinical features and partial proportional molecular genetics in neonatal diabetes mellitus: a retrospective analysis in southwestern China. Endocrine 2020; 69:53-62. [PMID: 32279225 DOI: 10.1007/s12020-020-02279-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 03/23/2020] [Indexed: 01/29/2023]
Abstract
PURPOSE To explore the relationship of phenotype and genotype of neonatal diabetes mellitus (NDM) in southwestern China. METHODS Sixteen cases of NDM admitted to Children's Hospital of Chongqing Medical University from May 2009 to May 2019 were included in this study. The clinical features of the included infants were retrospectively analyzed. Peripheral blood samples of the patients and their parents were collected for mutation detection. RESULTS Among the 16 cases of NDM, 8 cases were permanent neonatal diabetes mellitus (PNDM) (including 3 clinical syndromes), and 3 cases were transient neonatal diabetes mellitus (TNDM). Mutation detection was performed in six cases. The mutation genes and their loci were FOXP3 p.V408M, KCNJ11 p.C166Y, ABCC8 p.S830P, KCNJ11 p.I182T, KCNJ11 p.G334D, and ZFP57 p.R125X,412. ABCC8 p.S830P was the new found pathogenic site of gene mutation. According to the clinical features and follow-up results, one case was diagnosed as IPEX syndrome, two as DEND syndrome, two as simple PNDM, and one as TNDM. All the TNDM could spontaneously alleviate and then insulin was withdrawn. In PNDM, 75% of those with KATP channel gene mutation could be completely or partially converted to oral sulfonylureas treatment, however, the rest cases needed lifelong insulin replacement therapy. CONCLUSION The clinical manifestations and treatment regimens of patients with NDM vary according to the type of gene mutation. Even the same mutant genotype has differences in phenotype and response to treatment.
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Affiliation(s)
- Luying Cao
- Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Yi He
- Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Qinrong Huang
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Department of Rehabilitation, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Yu Zhang
- Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Pinglan Deng
- Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Weixia Du
- Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Ziyu Hua
- Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Min Zhu
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China
- Department of Endocrinology, Children's Hospital of Chongqing Medical University, Chongqing, PR China
| | - Hong Wei
- Department of Neonatology, Children's Hospital of Chongqing Medical University, Chongqing, PR China.
- Ministry of Education Key Laboratory of Child Development and Disorders; National Clinical Research Center for Child Health and Disorders; China International Science and Technology Cooperation base of Child development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, PR China.
- Chongqing Key Laboratory of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, PR China.
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14
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Pipatpolkai T, Usher S, Stansfeld PJ, Ashcroft FM. New insights into K ATP channel gene mutations and neonatal diabetes mellitus. Nat Rev Endocrinol 2020; 16:378-393. [PMID: 32376986 DOI: 10.1038/s41574-020-0351-y] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/17/2020] [Indexed: 12/12/2022]
Abstract
The ATP-sensitive potassium channel (KATP channel) couples blood levels of glucose to insulin secretion from pancreatic β-cells. KATP channel closure triggers a cascade of events that results in insulin release. Metabolically generated changes in the intracellular concentrations of adenosine nucleotides are integral to this regulation, with ATP and ADP closing the channel and MgATP and MgADP increasing channel activity. Activating mutations in the genes encoding either of the two types of KATP channel subunit (Kir6.2 and SUR1) result in neonatal diabetes mellitus, whereas loss-of-function mutations cause hyperinsulinaemic hypoglycaemia of infancy. Sulfonylurea and glinide drugs, which bind to SUR1, close the channel through a pathway independent of ATP and are now the primary therapy for neonatal diabetes mellitus caused by mutations in the genes encoding KATP channel subunits. Insight into the molecular details of drug and nucleotide regulation of channel activity has been illuminated by cryo-electron microscopy structures that reveal the atomic-level organization of the KATP channel complex. Here we review how these structures aid our understanding of how the various mutations in the genes encoding Kir6.2 (KCNJ11) and SUR1 (ABCC8) lead to a reduction in ATP inhibition and thereby neonatal diabetes mellitus. We also provide an update on known mutations and sulfonylurea therapy in neonatal diabetes mellitus.
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Affiliation(s)
- Tanadet Pipatpolkai
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Samuel Usher
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford, UK
- School of Life Sciences, University of Warwick, Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, UK
| | - Frances M Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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15
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Christensen SL, Munro G, Petersen S, Shabir A, Jansen-Olesen I, Kristensen DM, Olesen J. ATP sensitive potassium (K ATP) channel inhibition: A promising new drug target for migraine. Cephalalgia 2020; 40:650-664. [PMID: 32418458 DOI: 10.1177/0333102420925513] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Recently, the adenosine triphosphate (ATP) sensitive potassium channel opener levcromakalim was shown to induce migraine attacks with a far higher incidence than any previous provoking agent such as calcitonin gene-related peptide. Here, we show efficacy of ATP sensitive potassium channel inhibitors in two validated rodent models of migraine. METHODS In female spontaneous trigeminal allodynic rats, the sensitivity of the frontal region of the head was tested by an electronic von Frey filament device. In mice, cutaneous hypersensitivity was induced by repeated glyceryl trinitrate or levcromakalim injections over nine days, as measured with von Frey filaments in the hindpaw. Release of calcitonin gene-related peptide from dura mater and trigeminal ganglion was studied ex vivo. RESULTS The ATP sensitive potassium channel inhibitor glibenclamide attenuated the spontaneous cephalic hypersensitivity in spontaneous trigeminal allodynic rats and glyceryl trinitrate-induced hypersensitivity of the hindpaw in mice. It also inhibited CGRP release from dura mater and the trigeminal ganglion isolated from spontaneous trigeminal allodynic rats. The hypersensitivity was also diminished by the structurally different ATP sensitive potassium channel inhibitor gliquidone. Mice injected with the ATP sensitive potassium channel opener levcromakalim developed a progressive hypersensitivity that was completely blocked by glibenclamide, confirming target engagement. CONCLUSION The results suggest that ATP sensitive potassium channel inhibitors could be novel and highly effective drugs in the treatment of migraine.
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Affiliation(s)
- Sarah L Christensen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Righospitalet Glostrup, Glostrup, Denmark
| | - Gordon Munro
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Righospitalet Glostrup, Glostrup, Denmark
| | - Steffen Petersen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Righospitalet Glostrup, Glostrup, Denmark
| | - Anmool Shabir
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Righospitalet Glostrup, Glostrup, Denmark
| | - Inger Jansen-Olesen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Righospitalet Glostrup, Glostrup, Denmark
| | - David M Kristensen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Righospitalet Glostrup, Glostrup, Denmark.,Univ Rennes, Inserm, EHESP, Irset (Research Center for Environmental and Occupational Health), Rennes, France
| | - Jes Olesen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Righospitalet Glostrup, Glostrup, Denmark
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16
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Nicolaides NC, Kanaka-Gantenbein C, Papadopoulou-Marketou N, Sertedaki A, Chrousos GP, Papassotiriou I. Emerging technologies in pediatrics: the paradigm of neonatal diabetes mellitus. Crit Rev Clin Lab Sci 2020; 57:522-531. [PMID: 32356495 DOI: 10.1080/10408363.2020.1752141] [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] [Indexed: 10/24/2022]
Abstract
In the era of precision medicine, the tremendous progress in next-generation sequencing technologies has allowed the identification of an ever-increasing number of genes associated with known Mendelian disorders. Neonatal diabetes mellitus is a rare, genetically heterogeneous endocrine disorder diagnosed before 6 months of age. It may occur alone or in the context of genetic syndromes. Neonatal diabetes mellitus has been linked with genetic defects in at least 26 genes to date. Novel mutations in these disease-causing genes are being reported, giving us a better knowledge of the molecular events that occur upon insulin biosynthesis and secretion from the pancreatic β-cell. Of great importance, some of the identified genes encode proteins that can be therapeutically targeted by drugs per os, leading to transitioning from insulin to sulfonylureas. In this review, we provide an overview of pancreatic β-cell physiology, present the clinical manifestations and the genetic causes of the different forms of neonatal diabetes, and discuss the application of next-generation sequencing methods in the diagnosis and therapeutic management of neonatal diabetes and on research in this area.
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Affiliation(s)
- Nicolas C Nicolaides
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, "Aghia Sophia" Children's Hospital, Athens, Greece.,Division of Endocrinology and Metabolism, Center of Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.,University Research Institute of Maternal and Child Health and Precision Medicine, National and Kapodistrian University of Athens Medical School, Athens, Greece
| | - Christina Kanaka-Gantenbein
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, "Aghia Sophia" Children's Hospital, Athens, Greece
| | - Nektaria Papadopoulou-Marketou
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, "Aghia Sophia" Children's Hospital, Athens, Greece
| | - Amalia Sertedaki
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, "Aghia Sophia" Children's Hospital, Athens, Greece
| | - George P Chrousos
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, National and Kapodistrian University of Athens Medical School, "Aghia Sophia" Children's Hospital, Athens, Greece.,Division of Endocrinology and Metabolism, Center of Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.,University Research Institute of Maternal and Child Health and Precision Medicine, National and Kapodistrian University of Athens Medical School, Athens, Greece
| | - Ioannis Papassotiriou
- Department of Clinical Biochemistry, "Aghia Sophia" Children's Hospital, Athens, Greece.,IFCC Emerging Technologies Division, Emerging Technologies in Pediatric Laboratory Medicine (C-ETPLM), Milano, Italy
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17
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Khatami F, Mohajeri-Tehrani MR, Tavangar SM. The Importance of Precision Medicine in Type 2 Diabetes Mellitus (T2DM): From Pharmacogenetic and Pharmacoepigenetic Aspects. Endocr Metab Immune Disord Drug Targets 2020; 19:719-731. [PMID: 31122183 DOI: 10.2174/1871530319666190228102212] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 10/18/2018] [Accepted: 11/21/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND Type 2 Diabetes Mellitus (T2DM) is a worldwide disorder as the most important challenges of health-care systems. Controlling the normal glycaemia greatly profit long-term prognosis and gives explanation for early, effective, constant, and safe intervention. MATERIAL AND METHODS Finding the main genetic and epigenetic profile of T2DM and the exact molecular targets of T2DM medications can shed light on its personalized management. The comprehensive information of T2DM was earned through the genome-wide association study (GWAS) studies. In the current review, we represent the most important candidate genes of T2DM like CAPN10, TCF7L2, PPAR-γ, IRSs, KCNJ11, WFS1, and HNF homeoboxes. Different genetic variations of a candidate gene can predict the efficacy of T2DM personalized strategy medication. RESULTS SLCs and AMPK variations are considered for metformin, CYP2C9, KATP channel, CDKAL1, CDKN2A/2B and KCNQ1 for sulphonylureas, OATP1B, and KCNQ1 for repaglinide and the last but not the least ADIPOQ, PPAR-γ, SLC, CYP2C8, and SLCO1B1 for thiazolidinediones response prediction. CONCLUSION Taken everything into consideration, there is an extreme need to determine the genetic status of T2DM patients in some known genetic region before planning the medication strategies.
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Affiliation(s)
- Fatemeh Khatami
- Chronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad R Mohajeri-Tehrani
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed M Tavangar
- Chronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.,Department of Pathology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
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18
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Wu JX, Ding D, Wang M, Chen L. Structural Insights into the Inhibitory Mechanism of Insulin Secretagogues on the Pancreatic ATP-Sensitive Potassium Channel. Biochemistry 2019; 59:18-25. [PMID: 31566370 DOI: 10.1021/acs.biochem.9b00692] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Sulfonylureas and glinides are commonly used oral insulin secretagogues (ISs) that act on the pancreatic ATP-sensitive potassium (KATP) channel to promote insulin secretion in order to lower the blood glucose level. Physiologically, KATP channels are inhibited by intracellular ATP and activated by Mg-ADP. Therefore, they sense the cellular energy status to regulate the permeability of potassium ions across the plasma membrane. The pancreatic KATP channel is composed of the pore-forming Kir6.2 subunits and the regulatory SUR1 subunits. Previous electrophysiological studies have established that ISs bind to the SUR1 subunit and inhibit the channel activity primarily by two mechanisms. First, ISs prevent Mg-ADP activation. Second, ISs inhibit the channel activity of Kir6.2 directly. Several cryo-EM structures of the pancreatic KATP channel determined recently have provided remarkable structural insights into these two mechanisms.
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Affiliation(s)
- Jing-Xiang Wu
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine , Peking University , Beijing 100871 , China.,Peking-Tsinghua Center for Life Sciences , Peking University , Beijing 100871 , China
| | - Dian Ding
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine , Peking University , Beijing 100871 , China.,Peking-Tsinghua Center for Life Sciences , Peking University , Beijing 100871 , China.,Academy for Advanced Interdisciplinary Studies , Peking University , Beijing 100871 , China
| | - Mengmeng Wang
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine , Peking University , Beijing 100871 , China.,Peking-Tsinghua Center for Life Sciences , Peking University , Beijing 100871 , China.,Academy for Advanced Interdisciplinary Studies , Peking University , Beijing 100871 , China
| | - Lei Chen
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine , Peking University , Beijing 100871 , China.,Peking-Tsinghua Center for Life Sciences , Peking University , Beijing 100871 , China
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19
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Cyranka M, Veprik A, McKay EJ, van Loon N, Thijsse A, Cotter L, Hare N, Saibudeen A, Lingam S, Pires E, Larraufie P, Reimann F, Gribble F, Stewart M, Bentley E, Lear P, McCullagh J, Cantley J, Cox RD, de Wet H. Abcc5 Knockout Mice Have Lower Fat Mass and Increased Levels of Circulating GLP-1. Obesity (Silver Spring) 2019; 27:1292-1304. [PMID: 31338999 PMCID: PMC6658130 DOI: 10.1002/oby.22521] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 04/09/2019] [Indexed: 12/11/2022]
Abstract
OBJECTIVE A previous genome-wide association study linked overexpression of an ATP-binding cassette transporter, ABCC5, in humans with a susceptibility to developing type 2 diabetes with age. Specifically, ABCC5 gene overexpression was shown to be strongly associated with increased visceral fat mass and reduced peripheral insulin sensitivity. Currently, the role of ABCC5 in diabetes and obesity is unknown. This study reports the metabolic phenotyping of a global Abcc5 knockout mouse. METHODS A global Abcc5-/- mouse was generated by CRISPR/Cas9. Fat mass was determined by weekly EchoMRI and fat pads were dissected and weighed at week 18. Glucose homeostasis was ascertained by an oral glucose tolerance test, intraperitoneal glucose tolerance test, and intraperitoneal insulin tolerance test. Energy expenditure and locomotor activity were measured using PhenoMaster cages. Glucagon-like peptide 1 (GLP-1) levels in plasma, primary gut cell cultures, and GLUTag cells were determined by enzyme-linked immunosorbent assay. RESULTS Abcc5-/- mice had decreased fat mass and increased plasma levels of GLP-1, and they were more insulin sensitive and more active. Recombinant overexpression of ABCC5 protein in GLUTag cells decreased GLP-1 release. CONCLUSIONS ABCC5 protein expression levels are inversely related to fat mass and appear to play a role in the regulation of GLP-1 secretion from enteroendocrine cells.
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Affiliation(s)
- Malgorzata Cyranka
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Anna Veprik
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Eleanor J. McKay
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Nienke van Loon
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Amber Thijsse
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Luke Cotter
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Nisha Hare
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Affan Saibudeen
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Swathi Lingam
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | | | - Pierre Larraufie
- Wellcome Trust‐MRC Institute of Metabolic ScienceAddenbrooke's HospitalCambridgeUK
| | - Frank Reimann
- Wellcome Trust‐MRC Institute of Metabolic ScienceAddenbrooke's HospitalCambridgeUK
| | - Fiona Gribble
- Wellcome Trust‐MRC Institute of Metabolic ScienceAddenbrooke's HospitalCambridgeUK
| | - Michelle Stewart
- MRC Harwell Institute, Genetics of Type 2 DiabetesMammalian Genetics Unit, Harwell CampusOxfordshireUK
| | - Elizabeth Bentley
- MRC Harwell Institute, Genetics of Type 2 DiabetesMammalian Genetics Unit, Harwell CampusOxfordshireUK
| | - Pamela Lear
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | | | - James Cantley
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
| | - Roger D. Cox
- MRC Harwell Institute, Genetics of Type 2 DiabetesMammalian Genetics Unit, Harwell CampusOxfordshireUK
| | - Heidi de Wet
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
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20
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Ion Transporters, Channelopathies, and Glucose Disorders. Int J Mol Sci 2019; 20:ijms20102590. [PMID: 31137773 PMCID: PMC6566632 DOI: 10.3390/ijms20102590] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 01/19/2023] Open
Abstract
Ion channels and transporters play essential roles in excitable cells including cardiac, skeletal and smooth muscle cells, neurons, and endocrine cells. In pancreatic beta-cells, for example, potassium KATP channels link the metabolic signals generated inside the cell to changes in the beta-cell membrane potential, and ultimately regulate insulin secretion. Mutations in the genes encoding some ion transporter and channel proteins lead to disorders of glucose homeostasis (hyperinsulinaemic hypoglycaemia and different forms of diabetes mellitus). Pancreatic KATP, Non-KATP, and some calcium channelopathies and MCT1 transporter defects can lead to various forms of hyperinsulinaemic hypoglycaemia (HH). Mutations in the genes encoding the pancreatic KATP channels can also lead to different types of diabetes (including neonatal diabetes mellitus (NDM) and Maturity Onset Diabetes of the Young, MODY), and defects in the solute carrier family 2 member 2 (SLC2A2) leads to diabetes mellitus as part of the Fanconi–Bickel syndrome. Variants or polymorphisms in some ion channel genes and transporters have been reported in association with type 2 diabetes mellitus.
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21
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Sikimic J, McMillen TS, Bleile C, Dastvan F, Quast U, Krippeit-Drews P, Drews G, Bryan J. ATP binding without hydrolysis switches sulfonylurea receptor 1 (SUR1) to outward-facing conformations that activate K ATP channels. J Biol Chem 2018; 294:3707-3719. [PMID: 30587573 DOI: 10.1074/jbc.ra118.005236] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 12/19/2018] [Indexed: 11/06/2022] Open
Abstract
Neuroendocrine-type ATP-sensitive K+ (KATP) channels are metabolite sensors coupling membrane potential with metabolism, thereby linking insulin secretion to plasma glucose levels. They are octameric complexes, (SUR1/Kir6.2)4, comprising sulfonylurea receptor 1 (SUR1 or ABCC8) and a K+-selective inward rectifier (Kir6.2 or KCNJ11). Interactions between nucleotide-, agonist-, and antagonist-binding sites affect channel activity allosterically. Although it is hypothesized that opening these channels requires SUR1-mediated MgATP hydrolysis, we show here that ATP binding to SUR1, without hydrolysis, opens channels when nucleotide antagonism on Kir6.2 is minimized and SUR1 mutants with increased ATP affinities are used. We found that ATP binding is sufficient to switch SUR1 alone between inward- or outward-facing conformations with low or high dissociation constant, KD , values for the conformation-sensitive channel antagonist [3H]glibenclamide ([3H]GBM), indicating that ATP can act as a pure agonist. Assembly with Kir6.2 reduced SUR1's KD for [3H]GBM. This reduction required the Kir N terminus (KNtp), consistent with KNtp occupying a "transport cavity," thus positioning it to link ATP-induced SUR1 conformational changes to channel gating. Moreover, ATP/GBM site coupling was constrained in WT SUR1/WT Kir6.2 channels; ATP-bound channels had a lower KD for [3H]GBM than ATP-bound SUR1. This constraint was largely eliminated by the Q1179R neonatal diabetes-associated mutation in helix 15, suggesting that a "swapped" helix pair, 15 and 16, is part of a structural pathway connecting the ATP/GBM sites. Our results suggest that ATP binding to SUR1 biases KATP channels toward open states, consistent with SUR1 variants with lower KD values causing neonatal diabetes, whereas increased KD values cause congenital hyperinsulinism.
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Affiliation(s)
- Jelena Sikimic
- From the Institute of Pharmacy, Department of Pharmacology, University of Tübingen, D-72076 Tübingen, Germany and
| | - Timothy S McMillen
- Pacific Northwest Diabetes Research Institute, Seattle, Washington 98122, and
| | - Cita Bleile
- From the Institute of Pharmacy, Department of Pharmacology, University of Tübingen, D-72076 Tübingen, Germany and
| | - Frank Dastvan
- Pacific Northwest Diabetes Research Institute, Seattle, Washington 98122, and
| | - Ulrich Quast
- Department of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, D-72074 Tübingen, Germany
| | - Peter Krippeit-Drews
- From the Institute of Pharmacy, Department of Pharmacology, University of Tübingen, D-72076 Tübingen, Germany and
| | - Gisela Drews
- From the Institute of Pharmacy, Department of Pharmacology, University of Tübingen, D-72076 Tübingen, Germany and
| | - Joseph Bryan
- Pacific Northwest Diabetes Research Institute, Seattle, Washington 98122, and
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22
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Vedovato N, Rorsman O, Hennis K, Ashcroft FM, Proks P. Role of the C-terminus of SUR in the differential regulation of β-cell and cardiac K ATP channels by MgADP and metabolism. J Physiol 2018; 596:6205-6217. [PMID: 30179258 PMCID: PMC6292810 DOI: 10.1113/jp276708] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Abstract
Key points β‐Cell KATP channels are partially open in the absence of metabolic substrates, whereas cardiac KATP channels are closed. Using cloned channels heterologously expressed in Xenopus oocytes we measured the effect of MgADP on the MgATP concentration–inhibition curve immediately after patch excision. MgADP caused a far more striking reduction in ATP inhibition of Kir6.2/SUR1 channels than Kir6.2/SUR2A channels; this effect declined rapidly after patch excision. Exchanging the final 42 amino acids of SUR was sufficient to switch the Mg‐nucleotide regulation of Kir6.2/SUR1 and Kir6.2/SUR2A channels, and partially switch their sensitivity to metabolic inhibition. Deletion of the C‐terminal 42 residues of SUR abolished MgADP activation of both Kir6.2/SUR1 and Kir6.2/SUR2A channels. We conclude that the different metabolic sensitivity of Kir6.2/SUR1 and Kir6.2/SUR2A channels is at least partially due to their different regulation by Mg‐nucleotides, which is determined by the final 42 amino acids.
Abstract ATP‐sensitive potassium (KATP) channels couple the metabolic state of a cell to its electrical activity and play important physiological roles in many tissues. In contrast to β‐cell (Kir6.2/SUR1) channels, which open when extracellular glucose levels fall, cardiac (Kir6.2/SUR2A) channels remain closed. This is due to differences in the SUR subunit rather than cell metabolism. As ATP inhibition and MgADP activation are similar for both types of channels, we investigated channel inhibition by MgATP in the presence of 100 μm MgADP immediately after patch excision [when the channel open probability (PO) is near maximal]. The results were strikingly different: 100 μm MgADP substantially reduced MgATP inhibition of Kir6.2/SUR1, but had no effect on MgATP inhibition of Kir6.2/SUR2A. Exchanging the final 42 residues of SUR2A with that of SUR1 switched the channel phenotype (and vice versa), and deleting this region abolished Mg‐nucleotide activation. This suggests the C‐terminal 42 residues are important for the ability of MgADP to influence ATP inhibition at Kir6.2. This region was also necessary, but not sufficient, for activation of the KATP channel in intact cells by metabolic inhibition (azide). We conclude that the ability of MgADP to impair ATP inhibition at Kir6.2 accounts, in part, for the differential metabolic sensitivities of β‐cell and cardiac KATP channels. β‐Cell KATP channels are partially open in the absence of metabolic substrates, whereas cardiac KATP channels are closed. Using cloned channels heterologously expressed in Xenopus oocytes we measured the effect of MgADP on the MgATP concentration–inhibition curve immediately after patch excision. MgADP caused a far more striking reduction in ATP inhibition of Kir6.2/SUR1 channels than Kir6.2/SUR2A channels; this effect declined rapidly after patch excision. Exchanging the final 42 amino acids of SUR was sufficient to switch the Mg‐nucleotide regulation of Kir6.2/SUR1 and Kir6.2/SUR2A channels, and partially switch their sensitivity to metabolic inhibition. Deletion of the C‐terminal 42 residues of SUR abolished MgADP activation of both Kir6.2/SUR1 and Kir6.2/SUR2A channels. We conclude that the different metabolic sensitivity of Kir6.2/SUR1 and Kir6.2/SUR2A channels is at least partially due to their different regulation by Mg‐nucleotides, which is determined by the final 42 amino acids.
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Affiliation(s)
- Natascia Vedovato
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Olof Rorsman
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Konstantin Hennis
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Frances M Ashcroft
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
| | - Peter Proks
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford, OX1 3PT, UK
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23
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Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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24
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Mendes CP, Postal BG, Oliveira GTC, Castro AJG, Frederico MJS, Moraes ALL, Neuenfeldt PD, Nunes RJ, Menegaz D, Silva FRMB. Insulin stimulus‐secretion coupling is triggered by a novel thiazolidinedione/sulfonylurea hybrid in rat pancreatic islets. J Cell Physiol 2018; 234:509-520. [DOI: 10.1002/jcp.26746] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 04/13/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Camila P. Mendes
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
| | - Bárbara G. Postal
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
| | - Geisel T. C. Oliveira
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
- Núcleo de Bioeletricidade Celular (NUBIOCEL), Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
| | - Allisson J. G. Castro
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
| | - Marisa J. S. Frederico
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
| | - Ana L. L. Moraes
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
| | - Patrícia D. Neuenfeldt
- Universidade Federal de Santa Catarina, Departamento de Química, Centro de Ciências Físicas e MatemáticasCampus UniversitárioBairro Trindade, FlorianópolisSanta CatarinaBrazil
| | - Ricardo J. Nunes
- Universidade Federal de Santa Catarina, Departamento de Química, Centro de Ciências Físicas e MatemáticasCampus UniversitárioBairro Trindade, FlorianópolisSanta CatarinaBrazil
| | - Danusa Menegaz
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
- Núcleo de Bioeletricidade Celular (NUBIOCEL), Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
| | - Fátima R. M. B. Silva
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
- Núcleo de Bioeletricidade Celular (NUBIOCEL), Centro de Ciências Biológicas, Universidade Federal de Santa CatarinaCampus UniversitárioTrindade, FlorianópolisSanta CatarinaBrazil
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25
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Ramu Y, Xu Y, Lu Z. A novel high-affinity inhibitor against the human ATP-sensitive Kir6.2 channel. J Gen Physiol 2018; 150:969-976. [PMID: 29844136 DOI: 10.1085/jgp.201812017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/27/2018] [Indexed: 01/29/2023] Open
Abstract
The adenosine triphosphate (ATP)-sensitive (KATP) channels in pancreatic β cells couple the blood glucose level to insulin secretion. KATP channels in pancreatic β cells comprise the pore-forming Kir6.2 and the modulatory sulfonylurea receptor 1 (SUR1) subunits. Currently, there is no high-affinity and relatively specific inhibitor for the Kir6.2 pore. The importance of developing such inhibitors is twofold. First, in many cases, the lack of such an inhibitor precludes an unambiguous determination of the Kir6.2's role in certain physiological and pathological processes. This problem is exacerbated because Kir6.2 knockout mice do not yield the expected phenotypes of hyperinsulinemia and hypoglycemia, which in part, may reflect developmental adaptation. Second, mutations in Kir6.2 or SUR1 that increase the KATP current cause permanent neonatal diabetes mellitus (PNDM). Many patients who have PNDM have been successfully treated with sulphonylureas, a common class of antidiabetic drugs that bind to SUR1 and indirectly inhibit Kir6.2, thereby promoting insulin secretion. However, some PNDM-causing mutations render KATP channels insensitive to sulphonylureas. Conceptually, because these mutations are located intracellularly, an inhibitor blocking the Kir6.2 pore from the extracellular side might provide another approach to this problem. Here, by screening the venoms from >200 animals against human Kir6.2 coexpressed with SUR1, we discovered a small protein of 54 residues (SpTx-1) that inhibits the KATP channel from the extracellular side. It inhibits the channel with a dissociation constant value of 15 nM in a relatively specific manner and with an apparent one-to-one stoichiometry. SpTx-1 evidently inhibits the channel by primarily targeting Kir6.2 rather than SUR1; it inhibits not only wild-type Kir6.2 coexpressed with SUR1 but also a Kir6.2 mutant expressed without SUR1. Importantly, SpTx-1 suppresses both sulfonylurea-sensitive and -insensitive, PNDM-causing Kir6.2 mutants. Thus, it will be a valuable tool to investigate the channel's physiological and biophysical properties and to test a new strategy for treating sulfonylurea-resistant PNDM.
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Affiliation(s)
- Yajamana Ramu
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Yanping Xu
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Zhe Lu
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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26
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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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27
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Abstract
Since the discovery of the KATP channel in 1983, numerous studies have revealed its physiological functions. The KATP channel is expressed in various organs, including the pancreas, brain and skeletal muscles. It functions as a "metabolic sensor" that converts the metabolic status to electrical activity. In pancreatic beta-cells, the KATP channel regulates the secretion of insulin by sensing a change in the blood glucose level and thus maintains glucose homeostasis. In 2004, heterozygous gain-of-function mutations in the KCNJ11 gene, which encodes the Kir6.2 subunit of the KATP channel, were found to cause neonatal diabetes. In some mutations, diabetes is accompanied by severe neurological symptoms [developmental delay, epilepsy, neonatal diabetes (DEND) syndrome]. This review focuses on mutations of Kir6.2, the pore-forming subunit and sulfonylurea receptor (SUR) 1, the regulatory subunit of the KATP channel, which cause neonatal diabetes/DEND syndrome and also discusses the findings of the pathological mechanisms that are associated with neonatal diabetes, and its neurological features.
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Affiliation(s)
- Kenju Shimomura
- Department of Medical Electrophysiology, Fukushima Medical University School of Medicine, Japan
| | - Yuko Maejima
- Department of Medical Electrophysiology, Fukushima Medical University School of Medicine, Japan
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28
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Cooper PE, McClenaghan C, Chen X, Stary-Weinzinger A, Nichols CG. Conserved functional consequences of disease-associated mutations in the slide helix of Kir6.1 and Kir6.2 subunits of the ATP-sensitive potassium channel. J Biol Chem 2017; 292:17387-17398. [PMID: 28842488 DOI: 10.1074/jbc.m117.804971] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/04/2017] [Indexed: 11/06/2022] Open
Abstract
Cantu syndrome (CS) is a condition characterized by a range of anatomical defects, including cardiomegaly, hyperflexibility of the joints, hypertrichosis, and craniofacial dysmorphology. CS is associated with multiple missense mutations in the genes encoding the regulatory sulfonylurea receptor 2 (SUR2) subunits of the ATP-sensitive K+ (KATP) channel as well as two mutations (V65M and C176S) in the Kir6.1 (KCNJ8) subunit. Previous analysis of leucine and alanine substitutions at the Val-65-equivalent site (Val-64) in Kir6.2 indicated no major effects on channel function. In this study, we characterized the effects of both valine-to-methionine and valine-to-leucine substitutions at this position in both Kir6.1 and Kir6.2 using ion flux and patch clamp techniques. We report that methionine substitution, but not leucine substitution, results in increased open state stability and hence significantly reduced ATP sensitivity and a marked increase of channel activity in the intact cell irrespective of the identity of the coassembled SUR subunit. Sulfonylurea inhibitors, such as glibenclamide, are potential therapies for CS. However, as a consequence of the increased open state stability, both Kir6.1(V65M) and Kir6.2(V64M) mutations essentially abolish high-affinity sensitivity to the KATP blocker glibenclamide in both intact cells and excised patches. This raises the possibility that, at least for some CS mutations, sulfonylurea therapy may not prove to be successful and highlights the need for detailed pharmacogenomic analyses of CS mutations.
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Affiliation(s)
- Paige E Cooper
- From the Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Conor McClenaghan
- From the Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Xingyu Chen
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Anna Stary-Weinzinger
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria
| | - Colin G Nichols
- From the Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri 63110 and
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29
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Ashcroft FM, Puljung MC, Vedovato N. Neonatal Diabetes and the K ATP Channel: From Mutation to Therapy. Trends Endocrinol Metab 2017; 28:377-387. [PMID: 28262438 PMCID: PMC5582192 DOI: 10.1016/j.tem.2017.02.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 01/30/2017] [Accepted: 02/01/2017] [Indexed: 12/25/2022]
Abstract
Activating mutations in one of the two subunits of the ATP-sensitive potassium (KATP) channel cause neonatal diabetes (ND). This may be either transient or permanent and, in approximately 20% of patients, is associated with neurodevelopmental delay. In most patients, switching from insulin to oral sulfonylurea therapy improves glycemic control and ameliorates some of the neurological disabilities. Here, we review how KATP channel mutations lead to the varied clinical phenotype, how sulfonylureas exert their therapeutic effects, and why their efficacy varies with individual mutations.
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Affiliation(s)
- Frances M Ashcroft
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT, UK.
| | - Michael C Puljung
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT, UK
| | - Natascia Vedovato
- Henry Wellcome Centre for Gene Function, Department of Physiology, Anatomy and Genetics, University of Oxford, OX1 3PT, UK
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30
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Sood S, Landreth H, Bustinza J, Chalmers L, Thukaram R. Neonatal Diabetes: Case Report of a 9-Week-Old Presenting Diabetic Ketoacidosis Due to an Activating ABCC8 Gene Mutation. J Investig Med High Impact Case Rep 2017; 5:2324709617698718. [PMID: 28540314 PMCID: PMC5433553 DOI: 10.1177/2324709617698718] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 02/04/2017] [Accepted: 02/10/2017] [Indexed: 11/16/2022] Open
Abstract
Context: Neonatal diabetes mellitus, a rare condition occurring in approximately 1 in 500 000 live births, is defined as insulin-requiring hyperglycemia presenting in the first months of life. Neonatal diabetes can be transient or permanent, with studies characterizing the condition as a monogenic disorder. Case Report: We describe a case of a 9-week-old infant with neonatal diabetes who presented in diabetic ketoacidosis due to a mutation affecting the ABCC8 gene that encodes the SUR1 subunit of the potassium ATP channel. Conclusion: This genetic diagnosis has therapeutic implications regarding the initiation of sulfonylurea administration as 85% of patients with neonatal diabetes due to ABCC8 gene mutations can be successfully treated with oral sulfonylurea treatment.
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Affiliation(s)
- Shawn Sood
- The University of Oklahoma, Tulsa, OK, USA
| | | | | | | | - Roopa Thukaram
- The Children's Hospital at Saint Francis, Tulsa, OK, USA
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31
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Molecular action of sulphonylureas on KATP channels: a real partnership between drugs and nucleotides. Biochem Soc Trans 2016; 43:901-7. [PMID: 26517901 PMCID: PMC4613533 DOI: 10.1042/bst20150096] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Sulphonylureas stimulate insulin secretion from pancreatic β-cells primarily by closing ATP-sensitive K+ channels in the β-cell plasma membrane. The mechanism of channel inhibition by these drugs is unusually complex. As direct inhibitors of channel activity, sulphonylureas act only as partial antagonists at therapeutic concentrations. However, they also exert an additional indirect inhibitory effect via modulation of nucleotide-dependent channel gating. In this review, we summarize current knowledge and recent advances in our understanding of the molecular mechanism of action of these drugs.
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32
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The shifting landscape of KATP channelopathies and the need for 'sharper' therapeutics. Future Med Chem 2016; 8:789-802. [PMID: 27161588 DOI: 10.4155/fmc-2016-0005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
ATP-sensitive potassium (KATP) channels play fundamental roles in the regulation of endocrine, neural and cardiovascular function. Small-molecule inhibitors (e.g., sulfonylurea drugs) or activators (e.g., diazoxide) acting on SUR1 or SUR2 have been used clinically for decades to manage the inappropriate secretion of insulin in patients with Type 2 diabetes, hyperinsulinism and intractable hypertension. More recently, the discovery of rare disease-causing mutations in KATP channel-encoding genes has highlighted the need for new therapeutics for the treatment of certain forms of neonatal diabetes mellitus, congenital hyperinsulinism and Cantu syndrome. Here, we provide a high-level overview of the pathophysiology of these diseases and discuss the development of a flexible high-throughput screening platform to enable the development of new classes of KATP channel modulators.
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RamaKrishnan AM, Sankaranarayanan K. Understanding autoimmunity: The ion channel perspective. Autoimmun Rev 2016; 15:585-620. [PMID: 26854401 DOI: 10.1016/j.autrev.2016.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 01/29/2016] [Indexed: 12/11/2022]
Abstract
Ion channels are integral membrane proteins that orchestrate the passage of ions across the cell membrane and thus regulate various key physiological processes of the living system. The stringently regulated expression and function of these channels hold a pivotal role in the development and execution of various cellular functions. Malfunction of these channels results in debilitating diseases collectively termed channelopathies. In this review, we highlight the role of these proteins in the immune system with special emphasis on the development of autoimmunity. The role of ion channels in various autoimmune diseases is also listed out. This comprehensive review summarizes the ion channels that could be used as molecular targets in the development of new therapeutics against autoimmune disorders.
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Affiliation(s)
| | - Kavitha Sankaranarayanan
- AU-KBC Research Centre, Madras Institute of Technology, Anna University, Chrompet, Chennai 600 044, India.
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34
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Psichas A, Glass LL, Sharp SJ, Reimann F, Gribble FM. Galanin inhibits GLP-1 and GIP secretion via the GAL1 receptor in enteroendocrine L and K cells. Br J Pharmacol 2016; 173:888-98. [PMID: 26661062 PMCID: PMC4761093 DOI: 10.1111/bph.13407] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 11/26/2015] [Accepted: 12/03/2015] [Indexed: 12/19/2022] Open
Abstract
Background and Purpose Galanin is a widely expressed neuropeptide, which in the gut is thought to modulate gastrointestinal motility and secretion. We aimed to elucidate the poorly characterised mechanisms underlying the inhibitory effect of galanin and the potential involvement of G‐protein coupled inwardly rectifying potassium, Kir3, (GIRK) channels in glucagon‐like peptide 1 (GLP‐1) and glucose‐dependent insulinotropic polypeptide (GIP) secretion. Experimental Approach Purified murine L and K cells were analysed for expression of galanin receptors and GIRK subunits. Hormone secretion was measured from primary murine intestinal cultures. Intracellular cAMP was monitored in primary L cells derived from mice expressing the Epac2camps sensor under the control of the proglucagon promoter. Key Results Galanin receptor 1 (GAL1, Galr1) and GIRK channel 1 (Kir3.1, Kcnj3) and 4 (Kir3.4, Kcnj5) mRNA expression was highly enriched in K and L cells. Galanin and a selective GAL1 receptor agonist (M617) potently inhibited GLP‐1 and GIP secretion from primary small intestinal cultures. In L cells, galanin significantly inhibited the forskolin‐induced cAMP response. The GIRK1/4 activator ML297 significantly reduced glucose‐stimulated and IBMX‐stimulated GLP‐1 secretion but had no effect on GIP. The GIRK blocker tertiapin‐Q did not impair galanin‐mediated GLP‐1 inhibition. Conclusions and Implications Galanin, acting via the GAL1 receptor and Gi‐coupled signalling in L and K cells, is a potent inhibitor of GLP‐1 and GIP secretion. Although GIRK1/4 channels are expressed in these cells, their activation does not appear to play a major role in galanin‐mediated inhibition of incretin secretion.
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Affiliation(s)
- Arianna Psichas
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, WT-MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Leslie L Glass
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, WT-MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Stephen J Sharp
- MRC Epidemiology Unit, WT-MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Frank Reimann
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, WT-MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Fiona M Gribble
- Metabolic Research Laboratories and MRC Metabolic Diseases Unit, WT-MRC Institute of Metabolic Science, Addenbrooke's Hospital, University of Cambridge, Cambridge, CB2 0QQ, UK
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35
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Genetic markers predicting sulphonylurea treatment outcomes in type 2 diabetes patients: current evidence and challenges for clinical implementation. THE PHARMACOGENOMICS JOURNAL 2016; 16:209-19. [DOI: 10.1038/tpj.2015.95] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 10/25/2015] [Accepted: 11/13/2015] [Indexed: 12/17/2022]
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Kofent J, Spagnoli FM. Xenopus as a model system for studying pancreatic development and diabetes. Semin Cell Dev Biol 2016; 51:106-16. [PMID: 26806634 DOI: 10.1016/j.semcdb.2016.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/06/2016] [Indexed: 02/07/2023]
Abstract
Diabetes is a chronic disease caused by the loss or dysfunction of the insulin-producing β-cells in the pancreas. To date, much of our knowledge about β-cells in humans comes from studying rare monogenic forms of diabetes. Importantly, the majority of mutations so far associated to monogenic diabetes are in genes that exert a regulatory role in pancreatic development and/or β-cell function. Thus, the identification and study of novel mutations open an unprecedented window into human pancreatic development. In this review, we summarize major advances in the genetic dissection of different types of monogenic diabetes and the insights gained from a developmental perspective. We highlight future challenges to bridge the gap between the fast accumulation of genetic data through next-generation sequencing and the need of functional insights into disease mechanisms. Lastly, we discuss the relevance and advantages of studying candidate gene variants in vivo using the Xenopus as model system.
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Affiliation(s)
- Julia Kofent
- Max Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Str. 10, D-13125 Berlin, Germany
| | - Francesca M Spagnoli
- Max Delbrück Center for Molecular Medicine (MDC), Robert-Rössle-Str. 10, D-13125 Berlin, Germany.
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O'Connell SM, Proks P, Kramer H, Mattis KK, Sachse G, Joyce C, Houghton JAL, Ellard S, Hattersley AT, Ashcroft FM, O'Riordan SMP. The value of in vitro studies in a case of neonatal diabetes with a novel Kir6.2-W68G mutation. Clin Case Rep 2015; 3:884-7. [PMID: 26509030 PMCID: PMC4614663 DOI: 10.1002/ccr3.370] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/19/2015] [Accepted: 08/06/2015] [Indexed: 11/20/2022] Open
Abstract
In infants, especially with novel previously undescribed mutations of the KATP channel causing neonatal diabetes, in vitro studies can be used to both predict the response to sulphonylurea treatment and support a second trial of glibenclamide at higher than standard doses if the expected response is not observed.
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Affiliation(s)
- Susan M O'Connell
- Department of Paediatrics and Child Health, Cork University Hospital Cork, Ireland
| | - Peter Proks
- Department of Physiology Anatomy & Genetics Parks Road, University of Oxford Oxford, OX1 3PT, UK
| | - Holger Kramer
- Department of Physiology Anatomy & Genetics Parks Road, University of Oxford Oxford, OX1 3PT, UK
| | - Katia K Mattis
- Department of Physiology Anatomy & Genetics Parks Road, University of Oxford Oxford, OX1 3PT, UK
| | - Gregor Sachse
- Department of Physiology Anatomy & Genetics Parks Road, University of Oxford Oxford, OX1 3PT, UK
| | - Caroline Joyce
- Department of Biochemistry, Cork University Hospital Cork, Ireland
| | - Jayne A L Houghton
- Institute of Biomedical and Clinical Science, University of Exeter Medical School Exeter, EX2 5AD, UK
| | - Sian Ellard
- Institute of Biomedical and Clinical Science, University of Exeter Medical School Exeter, EX2 5AD, UK
| | - Andrew T Hattersley
- Institute of Biomedical and Clinical Science, University of Exeter Medical School Exeter, EX2 5AD, UK
| | - Frances M Ashcroft
- Department of Physiology Anatomy & Genetics Parks Road, University of Oxford Oxford, OX1 3PT, UK
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Systemic Administration of Glibenclamide Fails to Achieve Therapeutic Levels in the Brain and Cerebrospinal Fluid of Rodents. PLoS One 2015. [PMID: 26225433 PMCID: PMC4520580 DOI: 10.1371/journal.pone.0134476] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Activating mutations in the Kir6.2 (KCNJ11) subunit of the ATP-sensitive potassium channel cause neonatal diabetes (ND). Patients with severe mutations also suffer from neurological complications. Glibenclamide blocks the open KATP channels and is the treatment of choice for ND. However, although glibenclamide successfully restores normoglycaemia, it has a far more limited effect on the neurological problems. To assess the extent to which glibenclamide crosses the blood-brain barrier (BBB) in vivo, we quantified glibenclamide concentrations in plasma, cerebrospinal fluid (CSF), and brain tissue of rats, control mice, and mice expressing a human neonatal diabetes mutation (Kir6.2-V59M) selectively in neurones (nV59M mice). As only small sample volumes can be obtained from rodents, we developed a highly sensitive method of analysis, using liquid chromatography tandem mass spectrometry acquisition with pseudo-selected reaction monitoring, achieving a quantification limit of 10ng/ml (20nM) glibenclamide in a 30μl sample. Glibenclamide was not detectable in the CSF or brain of rats after implantation with subcutaneous glibenclamide pellets, despite high plasma concentrations. Further, one hour after a suprapharmacological glibenclamide dose was administered directly into the lateral ventricle of the brain, the plasma concentration was twice that of the CSF. This suggests the drug is rapidly exported from the CSF. Elacridar, an inhibitor of P-glycoprotein and breast cancer resistance protein (major multidrug resistance transporters at the BBB), did not affect glibenclamide levels in CSF and brain tissue. We also identified a reduced sensitivity to volatile anaesthetics in nV59M mice and showed this was not reversed by systemic delivery of glibenclamide. Our results therefore suggest that little glibenclamide reaches the central nervous system when given systemically, that glibenclamide is rapidly removed across the BBB when given intracranioventricularly, and that any glibenclamide that does enter (and is below our detection limit) is insufficient to influence neuronal function as assessed by anaesthesia sensitivity.
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Proks P, de Wet H, Ashcroft FM. Sulfonylureas suppress the stimulatory action of Mg-nucleotides on Kir6.2/SUR1 but not Kir6.2/SUR2A KATP channels: a mechanistic study. ACTA ACUST UNITED AC 2015; 144:469-86. [PMID: 25348414 PMCID: PMC4210431 DOI: 10.1085/jgp.201411222] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Sulfonylureas suppress the stimulatory effect of Mg-nucleotides on recombinant β-cell (Kir6.2/SUR1) but not cardiac (Kir6.2/SUR2A) KATP channels. Sulfonylureas, which stimulate insulin secretion from pancreatic β-cells, are widely used to treat both type 2 diabetes and neonatal diabetes. These drugs mediate their effects by binding to the sulfonylurea receptor subunit (SUR) of the ATP-sensitive K+ (KATP) channel and inducing channel closure. The mechanism of channel inhibition is unusually complex. First, sulfonylureas act as partial antagonists of channel activity, and second, their effect is modulated by MgADP. We analyzed the molecular basis of the interactions between the sulfonylurea gliclazide and Mg-nucleotides on β-cell and cardiac types of KATP channel (Kir6.2/SUR1 and Kir6.2/SUR2A, respectively) heterologously expressed in Xenopus laevis oocytes. The SUR2A-Y1206S mutation was used to confer gliclazide sensitivity on SUR2A. We found that both MgATP and MgADP increased gliclazide inhibition of Kir6.2/SUR1 channels and reduced inhibition of Kir6.2/SUR2A-Y1206S. The latter effect can be attributed to stabilization of the cardiac channel open state by Mg-nucleotides. Using a Kir6.2 mutation that renders the KATP channel insensitive to nucleotide inhibition (Kir6.2-G334D), we showed that gliclazide abolishes the stimulatory effects of MgADP and MgATP on β-cell KATP channels. Detailed analysis suggests that the drug both reduces nucleotide binding to SUR1 and impairs the efficacy with which nucleotide binding is translated into pore opening. Mutation of one (or both) of the Walker A lysines in the catalytic site of the nucleotide-binding domains of SUR1 may have a similar effect to gliclazide on MgADP binding and transduction, but it does not appear to impair MgATP binding. Our results have implications for the therapeutic use of sulfonylureas.
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Affiliation(s)
- Peter Proks
- Oxford Centre for Gene Function and Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, England, UK Oxford Centre for Gene Function and Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, England, UK
| | - Heidi de Wet
- Oxford Centre for Gene Function and Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, England, UK Oxford Centre for Gene Function and Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, England, UK
| | - Frances M Ashcroft
- Oxford Centre for Gene Function and Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, England, UK Oxford Centre for Gene Function and Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3PT, England, UK
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Kale VP, Amin SG, Pandey MK. Targeting ion channels for cancer therapy by repurposing the approved drugs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2747-55. [PMID: 25843679 DOI: 10.1016/j.bbamem.2015.03.034] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 03/18/2015] [Accepted: 03/27/2015] [Indexed: 12/21/2022]
Abstract
Ion channels have been shown to be involved in oncogenesis and efforts are being poured in to target the ion channels. There are many clinically approved drugs with ion channels as "off" targets. The question is, can these drugs be repurposed to inhibit ion channels for cancer treatment? Repurposing of drugs will not only save investors' money but also result in safer drugs for cancer patients. Advanced bioinformatics techniques and availability of a plethora of open access data on FDA approved drugs for various indications and omics data of large number of cancer types give a ray of hope to look for possibility of repurposing those drugs for cancer treatment. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.
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Affiliation(s)
- Vijay Pralhad Kale
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Shantu G Amin
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Manoj K Pandey
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
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Abstract
Diseases affecting endodermal organs like the pancreas, lung and gastrointestinal (GI) tract have a substantial impact on human welfare. Since many of these are congenital defects that arise as a result of defects during development broad efforts are focused on understanding the development of these organs so as to better identify risk factors, disease mechanisms and therapeutic targets. Studies implementing model systems, like the amphibian Xenopus, have contributed immensely to our understanding of signaling (e.g. Wnt, FGF, BMP, RA) pathways and gene regulation (e.g. hhex, ptf1a, ngn3) that underlie normal development as well as disease progression. Recent advances in genome engineering further enhance the capabilities of the Xenopus model system for pursuing biomedical research, and will undoubtedly result in a boom of new information underlying disease mechanisms ultimately leading to advancements in diagnosis and therapy.
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