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Ishii T, Kobayakawa T, Matsuda K, Nigorikawa K, Bolah P, Noborio A, Tsuji K, Ohashi N, Yoshimura K, Nomura W, Mitsuya H, Maeda K, Tamamura H. Discovery of Potent DAG-Lactone Derivatives as HIV Latency Reversing Agents. ACS Infect Dis 2024. [PMID: 38771724 DOI: 10.1021/acsinfecdis.4c00194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2024]
Abstract
Toward human immunodeficiency virus type-1 (HIV-1) cure, cells latently infected with HIV-1 must be eliminated from people living with HIV-1. We previously developed a protein kinase C (PKC) activator, diacylglycerol (DAG)-lactone derivative 3, with high HIV-1 latency-reversing activity, based on YSE028 (2) as a lead compound and found that the activity was correlated with binding affinity for PKC and stability against esterase-mediated hydrolysis. Here, we synthesized new DAG-lactone derivatives not only containing a tertiary ester group or an isoxazole surrogate but also several symmetric alkylidene moieties to improve HIV-1 latency reversing activity. Compound 9a, with a dimethyl group at the α-position of the ester group, exerted twice higher HIV-1 latency reversing activity than compound 3, and compound 26, with the isoxazole moiety, was significantly active. In addition, DAG-lactone derivatives with moderate hydrophobicity and potent biostability showed high biological activity.
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Affiliation(s)
- Takahiro Ishii
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Takuya Kobayakawa
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Kouki Matsuda
- Division of Antiviral Therapy, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, Kagoshima 890-8544, Japan
| | - Kiyomi Nigorikawa
- Department of Genome and Biomolecular Engineering for Drug Discovery, School of Pharmaceutical Sciences and Graduate School of Biomedical & Health Sciences, Hiroshima University, Minami-ku, Hiroshima 734-8553, Japan
| | - Peter Bolah
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Airi Noborio
- Division of Antiviral Therapy, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, Kagoshima 890-8544, Japan
| | - Kohei Tsuji
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
| | - Nami Ohashi
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Kazuhisa Yoshimura
- Institute of Public Health, Bureau of Social Welfare and Public Health, Tokyo Metropolitan Government, Shinjuku-ku, Tokyo 169-0073, Japan
| | - Wataru Nomura
- Department of Genome and Biomolecular Engineering for Drug Discovery, School of Pharmaceutical Sciences and Graduate School of Biomedical & Health Sciences, Hiroshima University, Minami-ku, Hiroshima 734-8553, Japan
| | - Hiroaki Mitsuya
- Department of Refractory Viral Infections, National Center for Global Health and Medicine Research Institute, Shinjuku-ku, Tokyo 162-8655, Japan
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
- Department of Clinical Sciences, Kumamoto University Hospital, Chuo-ku, Kumamoto 860-8556, Japan
| | - Kenji Maeda
- Division of Antiviral Therapy, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, Kagoshima 890-8544, Japan
| | - Hirokazu Tamamura
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo 101-0062, Japan
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Zhou M, Hanschmann EM, Römer A, Linn T, Petry SF. The significance of glutaredoxins for diabetes mellitus and its complications. Redox Biol 2024; 71:103043. [PMID: 38377787 PMCID: PMC10891345 DOI: 10.1016/j.redox.2024.103043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Accepted: 01/13/2024] [Indexed: 02/22/2024] Open
Abstract
Diabetes mellitus is a non-communicable metabolic disease hallmarked by chronic hyperglycemia caused by beta-cell failure. Diabetic complications affect the vasculature and result in macro- and microangiopathies, which account for a significantly increased morbidity and mortality. The rising incidence and prevalence of diabetes is a major global health burden. There are no feasible strategies for beta-cell preservation available in daily clinical practice. Therefore, patients rely on antidiabetic drugs or the application of exogenous insulin. Glutaredoxins (Grxs) are ubiquitously expressed and highly conserved members of the thioredoxin family of proteins. They have specific functions in redox-mediated signal transduction, iron homeostasis and biosynthesis of iron-sulfur (FeS) proteins, and the regulation of cell proliferation, survival, and function. The involvement of Grxs in chronic diseases has been a topic of research for several decades, suggesting them as therapeutic targets. Little is known about their role in diabetes and its complications. Therefore, this review summarizes the available literature on the significance of Grxs in diabetes and its complications. In conclusion, Grxs are differentially expressed in the endocrine pancreas and in tissues affected by diabetic complications, such as the heart, the kidneys, the eye, and the vasculature. They are involved in several pathways essential for insulin signaling, metabolic inflammation, glucose and fatty acid uptake and processing, cell survival, and iron and mitochondrial metabolism. Most studies describe significant changes in glutaredoxin expression and/or activity in response to the diabetic metabolism. In general, mitigated levels of Grxs are associated with oxidative distress, cell damage, and even cell death. The induced overexpression is considered a potential part of the cellular stress-response, counteracting oxidative distress and exerting beneficial impact on cell function such as insulin secretion, cytokine expression, and enzyme activity.
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Affiliation(s)
- Mengmeng Zhou
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
| | - Eva-Maria Hanschmann
- Experimental and Translational Research, Department of Otorhinolaryngology, University Hospital Essen, Essen, Germany
| | - Axel Römer
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
| | - Thomas Linn
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
| | - Sebastian Friedrich Petry
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, Giessen, Germany.
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Ishii T, Kobayakawa T, Matsuda K, Tsuji K, Ohashi N, Nakahata S, Noborio A, Yoshimura K, Mitsuya H, Maeda K, Tamamura H. Synthesis and evaluation of DAG-lactone derivatives with HIV-1 latency reversing activity. Eur J Med Chem 2023; 256:115449. [PMID: 37224601 PMCID: PMC10683555 DOI: 10.1016/j.ejmech.2023.115449] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/01/2023] [Accepted: 05/02/2023] [Indexed: 05/26/2023]
Abstract
Cells latently infected with human immunodeficiency virus type 1 (HIV-1) prevent people living with HIV-1 from obtaining a cure to the infectious disease. Latency reversing agents (LRAs) such as protein kinase C (PKC) activators and histone deacetylase (HDAC) inhibitors can reactivate cells latently infected with HIV-1. Several trials based on treatment with HDAC inhibitors alone, however, failed to reduce the number of latent HIV-1 reservoirs. Herein, we have focused on a diacylglycerol (DAG)-lactone derivative, YSE028 (1), which is a PKC activator with latency reversing activity and no significant cytotoxicity. Caspase-3 activation of YSE028 (1) led to cell apoptosis, specifically in HIV-1 latently infected cells. Structure-activity relationship studies of YSE028 (1) have produced several useful derivatives. Among these, compound 2 is approximately ten times more potent than YSE028 (1) in reactivation of cells latently infected with HIV-1. The activity of DAG-lactone derivatives was correlated with the binding affinity for PKC and the stability against esterase-mediated hydrolysis.
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Affiliation(s)
- Takahiro Ishii
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo, 101-0062, Japan
| | - Takuya Kobayakawa
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo, 101-0062, Japan
| | - Kouki Matsuda
- Division of Antiviral Therapy, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, 890-8544, Japan; AIDS Clinical Center, National Center for Global Health and Medicine Research Institute, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Kohei Tsuji
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo, 101-0062, Japan
| | - Nami Ohashi
- Laboratory of Drug Design and Medicinal Chemistry, Showa Pharmaceutical University, Machida, Tokyo, 194-8543, Japan
| | - Shingo Nakahata
- Division of HTLV-1/ATL Carcinogenesis and Therapeutics, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Airi Noborio
- Division of Antiviral Therapy, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Kazuhisa Yoshimura
- Institute of Public Health, Bureau of Social Welfare and Public Health, Tokyo Metropolitan Government, Shinjuku-ku, Tokyo, 169-0073, Japan
| | - Hiroaki Mitsuya
- Department of Refractory Viral Infections, National Center for Global Health and Medicine Research Institute, Shinjuku-ku, Tokyo, 162-8655, Japan; Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States; Department of Clinical Sciences, Kumamoto University Hospital, Chuo-ku, Kumamoto, 860-8556, Japan
| | - Kenji Maeda
- Division of Antiviral Therapy, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Hirokazu Tamamura
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), Chiyoda-ku, Tokyo, 101-0062, Japan.
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Al-Romaiyan A, Masocha W, Oyedemi S, Marafie SK, Huang GC, Jones PM, Persaud SJ. Commiphora myrrha stimulates insulin secretion from β-cells through activation of atypical protein kinase C and mitogen-activated protein kinase. J Ethnopharmacol 2023; 302:115937. [PMID: 36410575 DOI: 10.1016/j.jep.2022.115937] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 08/22/2022] [Accepted: 11/11/2022] [Indexed: 06/16/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Ayurvedic medicine has been used in the treatment of diabetes mellitus for centuries. In Arabia and some areas of Africa, Commiphora myrrha (CM) has been extensively used as a plant-based remedy. We have previously shown that an aqueous CM resin solution directly stimulates insulin secretion from MIN6 cells, a mouse β-cell line, and isolated mouse and human islets. However, the signaling pathways involved in CM-induced insulin secretion are completely unknown. Insulin secretion is normally triggered by elevations in intracellular Ca2+ ([Ca2+]i) through voltage gated Ca2+ channels (VGCC) and activation of protein kinases. Protein and lipid kinases such as protein kinase A (PKA), Ca2+-calmodulin dependent protein kinase II (CaMKII), phosphoinositide 3-kinases (PI3Ks), protein kinase C (PKC) and mitogen-activated protein kinase (MAPK), specifically extracellular signal-regulated kinases (ERK1/2), may be involved in receptor-operated insulin secretion. Therefore, we hypothesized that CM may induce insulin secretion by modulating the activity of VGCC and/or one or more of the above kinases. AIM OF THE STUDY To investigate the possible molecular mechanism of action of CM-induced insulin secretion. The effects of aqueous CM resin extract on [Ca2+]i and protein kinase activation from β-cells were examined. METHODS The effect of aqueous CM resin solution on [Ca2+]i was assessed using Ca2+ microfluorimetry. The involvement of VGCC in CM-induced insulin secretion was investigated using static and perifusion insulin secretion experiments in the presence of either EGTA, a Ca2+ chelator, or nifedipine, a blocker of VGCC. The involvement of kinase activation in the stimulatory effect of CM on insulin secretion was examined by using static and perifusion insulin secretion experiments in the presence of known pharmacological inhibitors and/or downregulation of specific kinases. The effects of CM on phosphorylation of PKCζ and ERK1/2 were also assessed using the Wes™ capillary-based protein electrophoresis. RESULTS Ca2+ microfluorimetry measurements showed that exposing MIN6 cells to CM (0.5-2 mg/mL) was not associated with changes in [Ca2+]i. Similarly, incubating MIN6 cells and mouse islets with EGTA and nifedipine, respectively, did not attenuate the insulin secretion induced by CM. However, incubating mouse and human islets with CM in the presence of staurosporine, a non-selective protein kinase inhibitor, completely blocked the effect of CM on insulin secretion. Exposing mouse islets to CM in the presence of H89, KN62 and LY294002, inhibitors of PKA, CaMKII and PI3K, respectively, did not reduce CM-induced insulin secretion. However, incubating mouse and human islets with CM in the presence of Ro 31-8220, a pan-PKC inhibitor, diminished insulin secretion stimulated by CM, whereas inhibiting the action of typical PKC (with Go6976) and PLCβ (with U73122) did not affect CM-stimulated insulin secretion. Similarly, downregulating typical and novel PKC by chronic exposure of mouse islets to phorbol 12-myristate 13-acetate (PMA) was also not associated with a decrease in the stimulatory effect of CM on insulin secretion. Interestingly, CM-induced insulin secretion from mouse islets was inhibited in the presence of the PKCζ inhibitor ZIP and a MAPK inhibitor PD 98059. In addition, Wes™ capillary-based protein electrophoresis indicated that expression of the phosphorylated forms of PKCζ and ERK1/2, a MAPK, was significantly increased following exposure of INS-1832/13 cells, a rat insulinoma cell line, to CM. CONCLUSIONS Our data indicate that CM directly stimulates insulin secretion through activating known downstream effectors of insulin-stimulus secretion coupling. Indeed, the increase in insulin secretion seen with CM is independent of changes in [Ca2+]i and does not involve activation of VGCC. Instead, the CM stimulatory effect on insulin secretion is completely dependent on protein kinase activation. Our findings indicate that CM could induce insulin exocytosis by stimulating the phosphorylation and activation of PKCζ, which in turn phosphorylates and activates ERK1/2.
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Affiliation(s)
- Altaf Al-Romaiyan
- Department of Pharmacology & Therapeutics, Faculty of Pharmacy, Kuwait University, Kuwait.
| | - Willias Masocha
- Department of Pharmacology & Therapeutics, Faculty of Pharmacy, Kuwait University, Kuwait.
| | - Sunday Oyedemi
- School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
| | - Sulaiman K Marafie
- Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait.
| | - Guo-Cai Huang
- Department of Diabetes, School of Cardiovascular Medicine &Sciences, Faculty of Life Sciences and Medicine, King's College London, UK.
| | - Peter M Jones
- Department of Diabetes, School of Cardiovascular Medicine &Sciences, Faculty of Life Sciences and Medicine, King's College London, UK.
| | - Shanta J Persaud
- Department of Diabetes, School of Cardiovascular Medicine &Sciences, Faculty of Life Sciences and Medicine, King's College London, UK.
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Tsuji K, Ishii T, Kobayakawa T, Ohashi N, Nomura W, Tamamura H. Fluorescence resonance energy transfer-based screening for protein kinase C ligands using 6-methoxynaphthalene-labeled 1,2-diacylglycerol-lactones. Org Biomol Chem 2021; 19:8264-8271. [PMID: 34338277 DOI: 10.1039/d1ob00814e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protein kinase C (PKC) is associated with a central cellular signal transduction pathway and disorders such as cancer and Alzheimer-type dementia and is therefore a target for the treatment of these diseases. The development of simple methods suitable for high-throughput screening to find potent PKC ligands is desirable. We have developed an assay based on fluorescence-quenching screening with a solvatochromic fluorophore attached to a competitive probe and its alternative method based on Förster/fluorescence resonance energy transfer (FRET) phenomena. Here, an improved FRET-based PKC binding assay using a diacylglycerol (DAG) lactone labeled with a donor fluorescent dye, 6-methoxynaphthalene (6MN), was developed. The 6MN-labeled DAG-lactone has a higher binding affinity for the PKCδ C1b domain and the fluorescent PKCδ C1b domain labeled by fluorescein as an acceptor fluorescent dye (Fl-δC1b) than the diethylaminocoumarin (DEAC)-labeled DAG-lactone. The combination of the 6MN-labeled DAG-lactone and Fl-δC1b showed a change in fluorescence response larger than that of the DEAC-labeled DAG-lactone and Fl-δC1b. The IC50 values of known PKC ligands calculated by the present FRET-based method using 6MN-labeled DAG-lactone agree well with the Ki values obtained by the conventional radioisotope-based assays. Some false positive compounds, identified by the previous solvatochromic fluorophore-based method, were found to be negative by this method. The present FRET-based PKC binding assay is more sensitive and could be more useful.
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Affiliation(s)
- Kohei Tsuji
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Takahiro Ishii
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Takuya Kobayakawa
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Nami Ohashi
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Wataru Nomura
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Hirokazu Tamamura
- Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU), 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
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Ježek P, Holendová B, Jabůrek M, Tauber J, Dlasková A, Plecitá-Hlavatá L. The Pancreatic β-Cell: The Perfect Redox System. Antioxidants (Basel) 2021; 10:antiox10020197. [PMID: 33572903 PMCID: PMC7912581 DOI: 10.3390/antiox10020197] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β-cell insulin secretion, which responds to various secretagogues and hormonal regulations, is reviewed here, emphasizing the fundamental redox signaling by NADPH oxidase 4- (NOX4-) mediated H2O2 production for glucose-stimulated insulin secretion (GSIS). There is a logical summation that integrates both metabolic plus redox homeostasis because the ATP-sensitive K+ channel (KATP) can only be closed when both ATP and H2O2 are elevated. Otherwise ATP would block KATP, while H2O2 would activate any of the redox-sensitive nonspecific calcium channels (NSCCs), such as TRPM2. Notably, a 100%-closed KATP ensemble is insufficient to reach the -50 mV threshold plasma membrane depolarization required for the activation of voltage-dependent Ca2+ channels. Open synergic NSCCs or Cl- channels have to act simultaneously to reach this threshold. The resulting intermittent cytosolic Ca2+-increases lead to the pulsatile exocytosis of insulin granule vesicles (IGVs). The incretin (e.g., GLP-1) amplification of GSIS stems from receptor signaling leading to activating the phosphorylation of TRPM channels and effects on other channels to intensify integral Ca2+-influx (fortified by endoplasmic reticulum Ca2+). ATP plus H2O2 are also required for branched-chain ketoacids (BCKAs); and partly for fatty acids (FAs) to secrete insulin, while BCKA or FA β-oxidation provide redox signaling from mitochondria, which proceeds by H2O2 diffusion or hypothetical SH relay via peroxiredoxin "redox kiss" to target proteins.
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Han YE, Chun JN, Kwon MJ, Ji YS, Jeong MH, Kim HH, Park SH, Rah JC, Kang JS, Lee SH, Ho WK. Endocytosis of K ATP Channels Drives Glucose-Stimulated Excitation of Pancreatic β Cells. Cell Rep 2019; 22:471-481. [PMID: 29320741 DOI: 10.1016/j.celrep.2017.12.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 11/02/2017] [Accepted: 12/14/2017] [Indexed: 11/30/2022] Open
Abstract
Insulin secretion from pancreatic β cells in response to high glucose (HG) critically depends on the inhibition of KATP channel activity in HG. It is generally believed that HG-induced effects are mediated by the increase in intracellular ATP, but here, we showed that, in INS-1 cells, endocytosis of KATP channel plays a major role. Upon HG stimulation, resting membrane potential depolarized by 30.6 mV (from -69.2 to -38.6 mV) and KATP conductance decreased by 91% (from 0.243 to 0.022 nS/pF), whereas intracellular ATP was increased by only 47%. HG stimulation induced internalization of KATP channels, causing a significant decrease in surface channel density, and this decrease was completely abolished by inhibiting endocytosis using dynasore, a dynamin inhibitor, or a PKC inhibitor. These drugs profoundly inhibited HG-induced depolarization. Our results suggest that the control of KATP channel surface density plays a greater role than ATP-dependent gating in regulating β cell excitability.
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Affiliation(s)
- Young-Eun Han
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Korea Brain Research Institute, Daegu 41068, Republic of Korea
| | - Jung Nyeo Chun
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Min Jeong Kwon
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Young-Sun Ji
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Myong-Ho Jeong
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Hye-Hyun Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Sun-Hyun Park
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Jong Cheol Rah
- Korea Brain Research Institute, Daegu 41068, Republic of Korea
| | - Jong-Sun Kang
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea
| | - Suk-Ho Lee
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Won-Kyung Ho
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Republic of Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 03080, Republic of Korea.
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Xie Y, Cui C, Nie A, Wang Y, Ni Q, Liu Y, Yin Q, Zhang H, Li Y, Wang Q, Gu Y, Ning G. The mTORC2/PKC pathway sustains compensatory insulin secretion of pancreatic β cells in response to metabolic stress. Biochim Biophys Acta Gen Subj 2017; 1861:2039-2047. [DOI: 10.1016/j.bbagen.2017.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/31/2017] [Accepted: 04/18/2017] [Indexed: 12/24/2022]
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Trexler AJ, Taraska JW. Regulation of insulin exocytosis by calcium-dependent protein kinase C in beta cells. Cell Calcium 2017; 67:1-10. [PMID: 29029784 DOI: 10.1016/j.ceca.2017.07.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/25/2017] [Accepted: 07/27/2017] [Indexed: 12/27/2022]
Abstract
The control of insulin release from pancreatic beta cells helps ensure proper blood glucose level, which is critical for human health. Protein kinase C has been shown to be one key control mechanism for this process. After glucose stimulation, calcium influx into beta cells triggers exocytosis of insulin-containing dense-core granules and activates protein kinase C via calcium-dependent phospholipase C-mediated generation of diacylglycerol. Activated protein kinase C potentiates insulin release by enhancing the calcium sensitivity of exocytosis, likely by affecting two main pathways that could be linked: (1) the reorganization of the cortical actin network, and (2) the direct phosphorylation of critical exocytotic proteins such as munc18, SNAP25, and synaptotagmin. Here, we review what is currently known about the molecular mechanisms of protein kinase C action on each of these pathways and how these effects relate to the control of insulin release by exocytosis. We identify remaining challenges in the field and suggest how these challenges might be addressed to advance our understanding of the regulation of insulin release in health and disease.
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Affiliation(s)
- Adam J Trexler
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States
| | - Justin W Taraska
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, United States.
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Ohashi N, Kobayashi R, Nomura W, Kobayakawa T, Czikora A, Herold BK, Lewin NE, Blumberg PM, Tamamura H. Synthesis and Evaluation of Dimeric Derivatives of Diacylglycerol-Lactones as Protein Kinase C Ligands. Bioconjug Chem 2017; 28:2135-2144. [PMID: 28671468 DOI: 10.1021/acs.bioconjchem.7b00299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein kinase C (PKC) mediates a central cellular signal transduction pathway involved in disorders such as cancer and Alzheimer's disease. PKC is regulated by binding of the second messenger sn-1,2-diacylglycerol (DAG) to its tandem C1 domains, designated C1a and C1b, leading both to PKC activation and to its translocation to the plasma membrane and to internal organelles. Depending on the isoform, there may be differences in the ligand selectivity of the C1a and C1b domains, and there is different spacing between the C1 domains of the conventional and novel PKCs. Bivalent ligands have the potential to exploit these differences between isoforms, yielding isoform selectivity. In the present study, we describe the synthesis of a series of dimeric derivatives of conformationally constrained diacylglycerol (DAG) analogs (DAG-lactones). We characterize the derivatives in vitro for their binding affinities, both to a single C1 domain (the C1b domain of PKCδ) as well as to the conventional PKCα isoform and the novel PKCδ isoform, and we measure their abilities to cause translocation of PKCδ and PKCε in intact cells. The dimeric compound with the 10-carbon linker was modestly more effective for the isolated PKCδ C1b domain than was the monomeric compound. For the intact PKCα and PKCδ, the shortest DAG-lactone dimer had similar affinity to the monomer and affinity decreased progressively up to the 16-carbon linker. The dimeric derivatives did not cause the Golgi accumulation of PKCδ. The present results provide important insights into the development of new chemical tools for biological studies on PKC.
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Affiliation(s)
- Nami Ohashi
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan
| | - Ryosuke Kobayashi
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan
| | - Wataru Nomura
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan
| | - Takuya Kobayakawa
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan
| | - Agnes Czikora
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Brienna K Herold
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Nancy E Lewin
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Peter M Blumberg
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda, Maryland 20892, United States
| | - Hirokazu Tamamura
- Department of Medicinal Chemistry, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University , 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan
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11
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Petry SF, Sharifpanah F, Sauer H, Linn T. Differential expression of islet glutaredoxin 1 and 5 with high reactive oxygen species production in a mouse model of diabesity. PLoS One 2017; 12:e0176267. [PMID: 28542222 PMCID: PMC5443478 DOI: 10.1371/journal.pone.0176267] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/07/2017] [Indexed: 01/14/2023] Open
Abstract
The onset and progression of diabetes mellitus type 2 is highly contingent on the amount of functional beta-cell mass. An underlying cause of beta-cell decay in diabetes is oxidative stress, which markedly affects the insulin producing pancreatic cells due to their poor antioxidant defence capacity. Consequently, disturbances of cellular redox signaling have been implicated to play a major role in beta-cell loss in diabetes mellitus type 2. There is evidence suggesting that the glutaredoxin (Grx) system exerts a protective role for pancreatic islets, but the exact mechanisms have not yet been elucidated. In this study, a mouse model for diabetes mellitus type 2 was used to gain further insight into the significance of Grx for the islets of Langerhans in the diabetic metabolism. We have observed distinct differences in the expression levels of Grx in pancreatic islets between obese, diabetic db mice and lean, non-diabetic controls. This finding is the first report about a decrease of Grx expression levels in pancreatic islets of diabetic mice which was accompanied by declining insulin secretion, increase of reactive oxygen species (ROS) production level, and cell cycle alterations. These data demonstrate the essential role of the Grx system for the beta-cell during metabolic stress which may provide a new target for diabetes mellitus type 2 treatment.
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Affiliation(s)
- Sebastian Friedrich Petry
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
- * E-mail:
| | - Fatemeh Sharifpanah
- Department of Physiology, Faculty of Medicine, Justus Liebig University, Giessen, Germany
| | - Heinrich Sauer
- Department of Physiology, Faculty of Medicine, Justus Liebig University, Giessen, Germany
| | - Thomas Linn
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
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12
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Santo-Domingo J, Chareyron I, Dayon L, Núñez Galindo A, Cominetti O, Pilar Giner Giménez M, De Marchi U, Canto C, Kussmann M, Wiederkehr A. Coordinated activation of mitochondrial respiration and exocytosis mediated by PKC signaling in pancreatic β cells. FASEB J 2016; 31:1028-1045. [PMID: 27927723 DOI: 10.1096/fj.201600837r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/22/2016] [Indexed: 12/17/2022]
Abstract
Mitochondria play a central role in pancreatic β-cell nutrient sensing by coupling their metabolism to plasma membrane excitability and insulin granule exocytosis. Whether non-nutrient secretagogues stimulate mitochondria as part of the molecular mechanism to promote insulin secretion is not known. Here, we show that PKC signaling, which is employed by many non-nutrient secretagogues, augments mitochondrial respiration in INS-1E (rat insulinoma cell line clone 1E) and human pancreatic β cells. The phorbol ester, phorbol 12-myristate 13-acetate, accelerates mitochondrial respiration at both resting and stimulatory glucose concentrations. A range of inhibitors of novel PKC isoforms prevent phorbol ester-induced respiration. Respiratory response was blocked by oligomycin that demonstrated PKC-dependent acceleration of mitochondrial ATP synthesis. Enhanced respiration was observed even when glycolysis was bypassed or fatty acid transport was blocked, which suggested that PKC regulates mitochondrial processes rather than upstream catabolic fluxes. A phosphoproteome study of phorbol ester-stimulated INS-1E cells maintained under resting (2.5 mM) glucose revealed a large number of phosphorylation sites that were altered during short-term activation of PKC signaling. The data set was enriched for proteins that are involved in gene expression, cytoskeleton remodeling, secretory vesicle transport, and exocytosis. Interactome analysis identified PKC, C-Raf, and ERK1/2 as the central phosphointeraction cluster. Prevention of ERK1/2 signaling by using a MEK1 inhibitor caused a marked decreased in phorbol 12-myristate 13-acetate-induced mitochondrial respiration. ERK1/2 signaling module therefore links PKC activation to downstream mitochondrial activation. We conclude that non-nutrient secretagogues act, in part, via PKC and downstream ERK1/2 signaling to stimulate mitochondrial energy production to compensate for energy expenditure that is linked to β-cell activation.-Santo-Domingo, J., Chareyron, I., Dayon, L., Galindo, A. N., Cominetti, O., Giménez, M. P. G., De Marchi, U., Canto, C., Kussmann, M., Wiederkehr, A. Coordinated activation of mitochondrial respiration and exocytosis mediated by PKC signaling in pancreatic β cells.
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Affiliation(s)
- Jaime Santo-Domingo
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Isabelle Chareyron
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Loïc Dayon
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Antonio Núñez Galindo
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Ornella Cominetti
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - María Pilar Giner Giménez
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Umberto De Marchi
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Carles Canto
- Diabetes and Metabolic Health, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Martin Kussmann
- Systems Nutrition, Metabonomics and Proteomics, Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - Andreas Wiederkehr
- Mitochondrial Function, Nestlé Institute of Health Sciences, Lausanne, Switzerland;
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Wuttke A, Yu Q, Tengholm A. Autocrine Signaling Underlies Fast Repetitive Plasma Membrane Translocation of Conventional and Novel Protein Kinase C Isoforms in β Cells. J Biol Chem 2016; 291:14986-95. [PMID: 27226533 PMCID: PMC4946917 DOI: 10.1074/jbc.m115.698456] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Indexed: 01/08/2023] Open
Abstract
PKC signaling has been implicated in the regulation of many cell functions, including metabolism, cell death, proliferation, and secretion. Activation of conventional and novel PKC isoforms is associated with their Ca2+- and/or diacylglycerol (DAG)-dependent translocation to the plasma membrane. In β cells, exocytosis of insulin granules evokes brief (<10 s) local DAG elevations (“spiking”) at the plasma membrane because of autocrine activation of P2Y1 purinoceptors by ATP co-released with insulin. Using total internal reflection microscopy, fluorescent protein-tagged PKCs, and signaling biosensors, we investigated whether DAG spiking causes membrane recruitment of PKCs and whether different classes of PKCs show characteristic responses. Glucose stimulation of MIN6 cells triggered DAG spiking with concomitant repetitive translocation of the novel isoforms PKCδ, PKCϵ, and PKCη. The conventional PKCα, PKCβI, and PKCβII isoforms showed a more complex pattern with both rapid and slow translocation. K+ depolarization-induced PKCϵ translocation entirely mirrored DAG spiking, whereas PKCβI translocation showed a sustained component, reflecting the subplasma membrane Ca2+ concentration ([Ca2+]pm), with additional effect during DAG spikes. Interference with DAG spiking by purinoceptor inhibition prevented intermittent translocation of PKCs and reduced insulin secretion but did not affect [Ca2+]pm elevation or sustained PKCβI translocation. The muscarinic agonist carbachol induced pronounced transient PKCβI translocation and sustained recruitment of PKCϵ. When rise of [Ca2+]pm was prevented, the carbachol-induced DAG and PKCϵ responses were somewhat reduced, but PKCβI translocation was completely abolished. We conclude that exocytosis-induced DAG spikes efficiently recruit both conventional and novel PKCs to the β cell plasma membrane. PKC signaling is thus implicated in autocrine regulation of β cell function.
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Affiliation(s)
- Anne Wuttke
- From the Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, 75123 Uppsala, Sweden
| | - Qian Yu
- From the Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, 75123 Uppsala, Sweden
| | - Anders Tengholm
- From the Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, 75123 Uppsala, Sweden
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Seed Ahmed M, Ahmed MS, Pelletier J, Leumann H, Gu HF, Östenson CG. Expression of Protein Kinase C Isoforms in Pancreatic Islets and Liver of Male Goto-Kakizaki Rats, a Model of Type 2 Diabetes. PLoS One 2015; 10:e0135781. [PMID: 26398746 PMCID: PMC4580567 DOI: 10.1371/journal.pone.0135781] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 07/27/2015] [Indexed: 02/03/2023] Open
Abstract
Protein kinase C (PKC) is a family of protein kinases controlling protein phosphorylation and playing important roles in the regulation of metabolism. We have investigated expression levels of PKC isoforms in pancreatic islets and liver of diabetic Goto-Kakizaki (GK) rats with and without insulin treatment to evaluate their association with glucose homeostasis. mRNA and protein expression levels of PKC isoforms were assessed in pancreatic islets and liver of Wistar rats and GK rats with or without insulin treatment. PKCα and PKCζ mRNA expressions were down-regulated in islets of GK compared with Wistar rats. PKCα and phosphorylated PKCα (p-PKCα) protein expressions were decreased in islets of GK compared with insulin-treated GK and Wistar rats. PKCζ protein expression in islets was reduced in GK and insulin-treated GK compared with Wistar rats, but p-PKCζ was decreased only in GK rats. Islet PKCε mRNA and protein expressions were lower in GK compared with insulin-treated GK and Wistar rats. In liver, PKCδ and PKCζ mRNA expressions were decreased in both GK and insulin-treated GK compared with Wistar rats. Hepatic PKCζ protein expression was diminished in both GK rats with and without insulin treatment compared with Wistar rats. Hepatic PKCε mRNA expression was down-regulated in insulin-treated GK compared with GK and Wistar rats. PKCα, PKCε, and p-PKCζ expressions were secondary to hyperglycaemia in GK rat islets. Hepatic PKCδ and PKCζ mRNA expressions were primarily linked to hyperglycaemia. Additionally, hepatic PKCε mRNA expression could be under control of insulin.
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Affiliation(s)
- Mohammed Seed Ahmed
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden; Department of Physiology, Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | | | - Julien Pelletier
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden
| | - Hannes Leumann
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden
| | - Harvest F Gu
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden
| | - Claes-Göran Östenson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Solna, Stockholm, Sweden
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15
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Inoue T, Hagiyama M, Yoneshige A, Kato T, Enoki E, Maenishi O, Chikugo T, Kimura M, Satou T, Ito A. Increased ectodomain shedding of cell adhesion molecule 1 from pancreatic islets in type 2 diabetic pancreata: correlation with hemoglobin A1c levels. PLoS One 2014; 9:e100988. [PMID: 24964098 PMCID: PMC4071031 DOI: 10.1371/journal.pone.0100988] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 05/31/2014] [Indexed: 01/09/2023] Open
Abstract
Pulmonary emphysema and type 2 diabetes mellitus (T2DM), both caused by lifestyle factors, frequently concur. Respectively, the diseases affect lung alveolar and pancreatic islet cells, which express cell adhesion molecule 1 (CADM1), an immunoglobulin superfamily member. Protease-mediated ectodomain shedding of full-length CADM1 produces C-terminal fragments (CTFs) with proapoptotic activity. In emphysematous lungs, the CADM1 shedding rate and thus the level of CTFs in alveolar cells increase. In this study, CADM1 expression in islet cells was examined by western blotting. Protein was extracted from formalin-fixed, paraffin-embedded sections of pancreata isolated from patients with T2DM (n = 12) or from patients without pancreatic disease (n = 8) at autopsy. After adjusting for the number of islet cells present in the adjacent section, we found that full-length CADM1 decreased in T2DM islets, while ectodomain shedding increased. Hemoglobin A1c levels, measured when patients were alive, correlated inversely with full-length CADM1 levels (P = 0.041) and positively with ectodomain shedding rates (P = 0.001). In immunofluorescence images of T2DM islet cells, CADM1 was detected in the cytoplasm, but not on the cell membrane. Consistently, when MIN6-m9 mouse beta cells were treated with phorbol ester and trypsin to induce shedding, CADM1 immunostaining was diffuse in the cytoplasm. When a form of CTFs was exogenously expressed in MIN6-m9 cells, it localized diffusely in the cytoplasm and increased the number of apoptotic cells. These results suggest that increased CADM1 ectodomain shedding contributes to blood glucose dysregulation in T2DM by decreasing full-length CADM1 and producing CTFs that accumulate in the cytoplasm and promote apoptosis of beta cells. Thus, this study has identified a molecular alteration shared by pulmonary emphysema and T2DM.
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Affiliation(s)
- Takao Inoue
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Man Hagiyama
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Azusa Yoneshige
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Takashi Kato
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Eisuke Enoki
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Osamu Maenishi
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Takaaki Chikugo
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Masatomo Kimura
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Takao Satou
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
| | - Akihiko Ito
- Department of Pathology, Faculty of Medicine, Kinki University, Osaka, Japan
- * E-mail:
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16
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Fernández-Millán E, Ramos S, Alvarez C, Bravo L, Goya L, Martín MÁ. Microbial phenolic metabolites improve glucose-stimulated insulin secretion and protect pancreatic beta cells against tert-butyl hydroperoxide-induced toxicity via ERKs and PKC pathways. Food Chem Toxicol 2014; 66:245-53. [PMID: 24491264 DOI: 10.1016/j.fct.2014.01.044] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 01/24/2014] [Accepted: 01/27/2014] [Indexed: 12/26/2022]
Abstract
Oxidative stress is accepted as one of the causes of beta cell failure in type 2 diabetes. Therefore, identification of natural antioxidant agents that preserve beta cell mass and function is considered an interesting strategy to prevent or treat diabetes. Recent evidences indicated that colonic metabolites derived from flavonoids could possess beneficial effects on various tissues. The aim of this work was to establish the potential anti-diabetic properties of the microbial-derived flavonoid metabolites 3,4-dihydroxyphenylacetic acid (DHPAA), 2,3-dihydroxybenzoic acid (DHBA) and 3-hydroxyphenylpropionic acid (HPPA). To this end, we tested their ability to influence beta cell function and to protect against tert-butyl hydroperoxide-induced beta cell toxicity. DHPAA and HPPA were able to potentiate glucose-stimulated insulin secretion (GSIS) in a beta cell line INS-1E and in rat pancreatic islets. Moreover, pre-treatment of cells with both compounds protected against beta cell dysfunction and death induced by the pro-oxidant. Finally, experiments with pharmacological inhibitors indicate that these effects were mediated by the activation of protein kinase C and the extracellular regulated kinases pathways. Altogether, these findings strongly suggest that the microbial-derived flavonoid metabolites DHPAA and HPPA may have anti-diabetic potential by promoting survival and function of pancreatic beta cells.
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Affiliation(s)
- Elisa Fernández-Millán
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Sonia Ramos
- Departamento de Metabolismo y Nutrición, Instituto de Ciencia y Tecnología de los Alimentos y Nutrición (ICTAN), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Carmen Alvarez
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III (ISCIII), Madrid, Spain; Departamento de Bioquímica y Biología Molecular II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain
| | - Laura Bravo
- Departamento de Metabolismo y Nutrición, Instituto de Ciencia y Tecnología de los Alimentos y Nutrición (ICTAN), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Luis Goya
- Departamento de Metabolismo y Nutrición, Instituto de Ciencia y Tecnología de los Alimentos y Nutrición (ICTAN), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - María Ángeles Martín
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III (ISCIII), Madrid, Spain; Departamento de Metabolismo y Nutrición, Instituto de Ciencia y Tecnología de los Alimentos y Nutrición (ICTAN), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
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Kurohane Kaneko Y, Kobayashi Y, Motoki K, Nakata K, Miyagawa S, Yamamoto M, Hayashi D, Shirai Y, Sakane F, Ishikawa T. Depression of type I diacylglycerol kinases in pancreatic β-cells from male mice results in impaired insulin secretion. Endocrinology 2013; 154:4089-98. [PMID: 24035999 DOI: 10.1210/en.2013-1356] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Diacylglycerol kinase (DGK) catalyzes the conversion of diacylglycerol (DAG) to phosphatidic acid. This study investigated the expression and function of DGK in pancreatic β-cells. mRNA expression of type I DGK isoforms (α, β, γ) was detected in mouse pancreatic islets and the β-cell line MIN6. Protein expression of DGKα and DGKγ was also detected in mouse β-cells and MIN6 cells. The type I DGK inhibitor R59949 inhibited high K(+)- and glucose-induced insulin secretion in MIN6 cells. Moreover, single knockdown of DGKα or DGKγ by small interfering RNA slightly but significantly decreased glucose- and high K(+)-induced insulin secretions, and the double knockdown further decreased them to the levels comparable with those induced by R59949. R59949 and DiC8, a membrane permeable DAG analog, decreased intracellular Ca(2+) concentration elevated by glucose and high K(+) in MIN6 cells. Real-time imaging in MIN6 cells expressing green fluorescent protein-tagged DGKα or DGKγ showed that the DGK activator phorbol 12-myristate 13-acetate rapidly induced translocation of DGKγ to the plasma membrane, whereas high K(+) slowly translocated DGKα and DGKγ to the plasma membrane. R59949 increased the DAG content in MIN6 cells when stimulated with high KCl, whereas it did not increase the DAG content but decreased the phosphatidic acid content when stimulated with high glucose. Finally, R59949 was confirmed to inhibit high K(+)-induced insulin secretion from mouse islets and glucose-induced insulin secretion from rat islets. These results suggest that DGKα and DGKγ are present in β-cells and that the depression of these DGKs causes a decrease in intracellular Ca(2+) concentration, thereby reducing insulin secretion.
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Beaudry JL, D'souza AM, Teich T, Tsushima R, Riddell MC. Exogenous glucocorticoids and a high-fat diet cause severe hyperglycemia and hyperinsulinemia and limit islet glucose responsiveness in young male Sprague-Dawley rats. Endocrinology 2013; 154:3197-208. [PMID: 23766132 DOI: 10.1210/en.2012-2114] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Corticosterone (CORT) and other glucocorticoids cause peripheral insulin resistance and compensatory increases in β-cell mass. A prolonged high-fat diet (HFD) induces insulin resistance and impairs β-cell insulin secretion. This study examined islet adaptive capacity in rats treated with CORT and a HFD. Male Sprague-Dawley rats (age ∼6 weeks) were given exogenous CORT (400 mg/rat) or wax (placebo) implants and placed on a HFD (60% calories from fat) or standard diet (SD) for 2 weeks (N = 10 per group). CORT-HFD rats developed fasting hyperglycemia (>11 mM) and hyperinsulinemia (∼5-fold higher than controls) and were 15-fold more insulin resistant than placebo-SD rats by the end of ∼2 weeks (Homeostatic Model Assessment for Insulin Resistance [HOMA-IR] levels, 15.08 ± 1.64 vs 1.0 ± 0.12, P < .05). Pancreatic β-cell function, as measured by HOMA-β, was lower in the CORT-HFD group as compared to the CORT-SD group (1.64 ± 0.22 vs 3.72 ± 0.64, P < .001) as well as acute insulin response (0.25 ± 0.22 vs 1.68 ± 0.41, P < .05). Moreover, β- and α-cell mass were 2.6- and 1.6-fold higher, respectively, in CORT-HFD animals compared to controls (both P < .05). CORT treatment increased p-protein kinase C-α content in SD but not HFD-fed rats, suggesting that a HFD may lower insulin secretory capacity via impaired glucose sensing. Isolated islets from CORT-HFD animals secreted more insulin in both low and high glucose conditions; however, total insulin content was relatively depleted after glucose challenge. Thus, CORT and HFD, synergistically not independently, act to promote severe insulin resistance, which overwhelms islet adaptive capacity, thereby resulting in overt hyperglycemia.
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Affiliation(s)
- Jacqueline L Beaudry
- School of Kinesiology and Health Science, Faculty of Health, Muscle Health Research Center and Physical Activity and Chronic Disease Unit, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3
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Portha B, Giroix MH, Tourrel-Cuzin C, Le-Stunff H, Movassat J. The GK rat: a prototype for the study of non-overweight type 2 diabetes. Methods Mol Biol 2012; 933:125-59. [PMID: 22893405 DOI: 10.1007/978-1-62703-068-7_9] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Type 2 diabetes mellitus (T2D) arises when the endocrine pancreas fails to secrete sufficient insulin to cope with the metabolic demand because of β-cell secretory dysfunction and/or decreased β-cell mass. Defining the nature of the pancreatic islet defects present in T2D has been difficult, in part because human islets are inaccessible for direct study. This review is aimed to illustrate to what extent the Goto Kakizaki rat, one of the best characterized animal models of spontaneous T2D, has proved to be a valuable tool offering sufficient commonalities to study this aspect. A comprehensive compendium of the multiple functional GK abnormalities so far identified is proposed in this perspective, together with their time-course and interactions. A special focus is given toward the pathogenesis of defective β-cell number and function in the GK model. It is proposed that the development of T2D in the GK model results from the complex interaction of multiple events: (1) several susceptibility loci containing genes responsible for some diabetic traits; (2) gestational metabolic impairment inducing an epigenetic programming of the offspring pancreas and the major insulin target tissues; and (3) environmentally induced loss of β-cell differentiation due to chronic exposure to hyperglycemia/hyperlipidemia, inflammation, and oxidative stress.
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Affiliation(s)
- Bernard Portha
- Laboratoire B2PE (Biologie et Pathologie du Pancréas Endocrine), Unité BFA (Biologie Fonctionnelle et Adaptive), Université Paris-Diderot, CNRS EAC 4413, Paris, France.
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Sancho V, Berna MJ, Thill M, Jensen RT. PKCθ activation in pancreatic acinar cells by gastrointestinal hormones/neurotransmitters and growth factors is needed for stimulation of numerous important cellular signaling cascades. Biochim Biophys Acta 2011; 1813:2145-56. [PMID: 21810446 DOI: 10.1016/j.bbamcr.2011.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 07/12/2011] [Accepted: 07/13/2011] [Indexed: 02/08/2023]
Abstract
The novel PKCθ isoform is highly expressed in T-cells, brain and skeletal muscle and originally thought to have a restricted distribution. It has been extensively studied in T-cells and shown to be important for apoptosis, T-cell activation and proliferation. Recent studies showed its presence in other tissues and importance in insulin signaling, lung surfactant secretion, intestinal barrier permeability, platelet and mast-cell functions. However, little information is available for PKCθ activation by gastrointestinal (GI) hormones/neurotransmitters and growth factors. In the present study we used rat pancreatic acinar cells to explore their ability to activate PKCθ and the possible interactions with important cellular mediators of their actions. Particular attention was paid to cholecystokinin (CCK), a physiological regulator of pancreatic function and important in pathological processes affecting acinar function, like pancreatitis. PKCθ-protein/mRNA was present in the pancreatic acini, and T538-PKCθ phosphorylation/activation was stimulated only by hormones/neurotransmitters activating phospholipase C. PKCθ was activated in time- and dose-related manner by CCK, mediated 30% by high-affinity CCK(A)-receptor activation. CCK stimulated PKCθ translocation from cytosol to membrane. PKCθ inhibition (by pseudostrate-inhibitor or dominant negative) inhibited CCK- and TPA-stimulation of PKD, Src, RafC, PYK2, p125(FAK) and IKKα/β, but not basal/stimulated enzyme secretion. Also CCK- and TPA-induced PKCθ activation produced an increment in PKCθ's direct association with AKT, RafA, RafC and Lyn. These results show for the first time the PKCθ presence in pancreatic acinar cells, its activation by some GI hormones/neurotransmitters and involvement in important cell signaling pathways mediating physiological responses (enzyme secretion, proliferation, apoptosis, cytokine expression, and pathological responses like pancreatitis and cancer growth).
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Affiliation(s)
- Veronica Sancho
- Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1804, USA
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Han S, Pan H, Zhang J, Tan L, Ma D, Yuan J, Wu JR. Identification of a small molecule activator of novel PKCs for promoting glucose-dependent insulin secretion. Cell Res 2011; 21:588-99. [PMID: 20877311 DOI: 10.1038/cr.2010.137] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Using an image-based screen for small molecules that can affect Golgi morphology, we identify a small molecule, Sioc145, which can enlarge the Golgi compartments and promote protein secretion. More importantly, Sioc145 potentiates insulin secretion in a glucose-dependent manner. We show that Sioc145 selectively activates novel protein kinase Cs (nPKCs; δ and ɛ) but not conventional PKCs (cPKCs; α, βI and βII) in INS-1E insulinoma cells. In contrast, PMA, a non-selective activator of cPKCs and nPKCs, promotes insulin secretion independent of glucose concentrations. Furthermore, we demonstrate that Sioc145 and PMA show differential abilities in depolarizing the cell membrane, and suggest that Sioc145 promotes insulin secretion in the amplifying pathway downstream of K(ATP) channels. In pancreatic islets, the treatment with Sioc145 enhances the second phase of insulin secretion. Increased insulin granules close to the plasma membrane are observed after Sioc145 treatment. Finally, the administration of Sioc145 to diabetic GK rats increases their serum insulin levels and improves glucose tolerance. Collectively, our studies identify Sioc145 as a novel glucose-dependent insulinotropic compound via selectively activating nPKCs.
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Amaral AG, Rafacho A, Machado de Oliveira CA, Batista TM, Ribeiro RA, Latorraca MQ, Boschero AC, Carneiro EM. Leucine supplementation augments insulin secretion in pancreatic islets of malnourished mice. Pancreas 2010; 39:847-55. [PMID: 20697208 DOI: 10.1097/MPA.0b013e3181d37210] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVES We investigated the influence of leucine supplementation on insulin secretion and on some proteins related to insulin secretion in malnourished mice. METHODS Swiss mice (aged 21 days) received isocaloric normo-17% (NP) or 6% low-protein (LP) diet for 120 days. Half of the NP and LP mice received 1.5% leucine in the drinking water during the last 30 days (NPL and LPL, respectively). RESULTS The LP mice were hypoinsulinemic compared with the NP group, whereas LPL mice exhibited increased insulinemia in the fed state versus LP mice. The LP mouse islets were less responsive to 22.2 mM glucose, 100 microM carbachol (Cch), and 10 mM leucine than the NP group. However, LPL islets were more responsive to all these conditions compared with the LP group. The muscarinic type 3 receptor, (M3R) Cabeta2, and PKC-alpha protein contents were reduced in LP compared with NP islets but significantly higher in LPL than LP islets. The p-AKT/AKT ratio was higher in LPL compared with LP islets. CONCLUSIONS Leucine supplementation increases insulin secretion in response to glucose and leucine and to agents that potentiate secretion, such as Cch, in malnourished mice. The enhanced levels of M3R, Cabeta2, and PKC-alpha proteins, as well as of the p-AKT/AKT ratio, may play a role in this process.
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Manna PT, Smith AJ, Taneja TK, Howell GJ, Lippiat JD, Sivaprasadarao A. Constitutive endocytic recycling and protein kinase C-mediated lysosomal degradation control K(ATP) channel surface density. J Biol Chem 2010; 285:5963-73. [PMID: 20026601 PMCID: PMC2820821 DOI: 10.1074/jbc.m109.066902] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 12/07/2009] [Indexed: 11/06/2022] Open
Abstract
Pancreatic ATP-sensitive potassium (K(ATP)) channels control insulin secretion by coupling the excitability of the pancreatic beta-cell to glucose metabolism. Little is currently known about how the plasma membrane density of these channels is regulated. We therefore set out to examine in detail the endocytosis and recycling of these channels and how these processes are regulated. To achieve this goal, we expressed K(ATP) channels bearing an extracellular hemagglutinin epitope in human embryonic kidney cells and followed their fate along the endocytic pathway. Our results show that K(ATP) channels undergo multiple rounds of endocytosis and recycling. Further, activation of protein kinase C (PKC) with phorbol 12-myristate 13-acetate significantly decreases K(ATP) channel surface density by reducing channel recycling and diverting the channel to lysosomal degradation. These findings were recapitulated in the model pancreatic beta-cell line INS1e, where activation of PKC leads to a decrease in the surface density of native K(ATP) channels. Because sorting of internalized channels between lysosomal and recycling pathways could have opposite effects on the excitability of pancreatic beta-cells, we propose that PKC-regulated K(ATP) channel trafficking may play a role in the regulation of insulin secretion.
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Affiliation(s)
- Paul T. Manna
- From the Multidisciplinary Cardiovascular Research Centre, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Andrew J. Smith
- From the Multidisciplinary Cardiovascular Research Centre, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Tarvinder K. Taneja
- From the Multidisciplinary Cardiovascular Research Centre, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Gareth J. Howell
- From the Multidisciplinary Cardiovascular Research Centre, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Jonathan D. Lippiat
- From the Multidisciplinary Cardiovascular Research Centre, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Asipu Sivaprasadarao
- From the Multidisciplinary Cardiovascular Research Centre, Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
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Portha B, Lacraz G, Chavey A, Figeac F, Fradet M, Tourrel-Cuzin C, Homo-Delarche F, Giroix MH, Bailbé D, Gangnerau MN, Movassat J. Islet structure and function in the GK rat. Adv Exp Med Biol 2010; 654:479-500. [PMID: 20217511 DOI: 10.1007/978-90-481-3271-3_21] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Type 2 diabetes mellitus (T2D) arises when the endocrine pancreas fails to secrete sufficient insulin to cope with the metabolic demand because of beta-cell secretory dysfunction and/or decreased beta-cell mass. Defining the nature of the pancreatic islet defects present in T2D has been difficult, in part because human islets are inaccessible for direct study. This review is aimed to illustrate to what extent the Goto-Kakizaki rat, one of the best characterized animal models of spontaneous T2D, has proved to be a valuable tool offering sufficient commonalities to study this aspect. A comprehensive compendium of the multiple functional GK islet abnormalities so far identified is proposed in this perspective. The pathogenesis of defective beta-cell number and function in the GK model is also discussed. It is proposed that the development of T2D in the GK model results from the complex interaction of multiple events: (i) several susceptibility loci containing genes responsible for some diabetic traits (distinct loci encoding impairment of beta-cell metabolism and insulin exocytosis, but no quantitative trait locus for decreased beta-cell mass); (ii) gestational metabolic impairment inducing an epigenetic programming of the offspring pancreas (decreased beta-cell neogenesis and proliferation) transmitted over generations; and (iii) loss of beta-cell differentiation related to chronic exposure to hyperglycaemia/hyperlipidaemia, islet inflammation, islet oxidative stress, islet fibrosis and perturbed islet vasculature.
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Affiliation(s)
- Bernard Portha
- Laboratoire B2PE, Unité BFA, Université Paris-Diderot et CNRS EAC4413, F - 75205 Paris Cedex13, France.
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25
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Edholm T, Cejvan K, Abdel-Halim SM, Efendic S, Schmidt PT, Hellström PM. The incretin hormones GIP and GLP-1 in diabetic rats: effects on insulin secretion and small bowel motility. Neurogastroenterol Motil 2009; 21:313-21. [PMID: 19126188 DOI: 10.1111/j.1365-2982.2008.01229.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Incretin hormones often display inhibitory actions on gut motility. The aim of this study was to investigate if altered responsiveness to glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1) as regards insulin release and small bowel motility could bring further clarity to the pathophysiology of diabetes in the Goto-Kakizaki (GK) rat. The isolated perfused pancreas was studied in male GK and Wistar rats (controls) under euglycemic and hyperglycemic conditions. Glucose-dependent insulinotropic peptide (10 nmol L(-1)) or GLP-1 (10 nmol L(-1)) were added to the medium and perfusate was collected and analysed for insulin. Moreover, GK and Wistar rats were supplied with bipolar electrodes in the small bowel and myoelectric activity was recorded during intravenous administration of GIP (1-400 pmol kg(-1) min(-1)) or GLP-1 (0.1-20 pmol kg(-1) min(-1)). Finally, tissue was collected from GK and Wistar rats for RNA extraction. Under euglycemia, GIP and GLP-1 stimulated the initial insulin response by 10-fold in GK rats (P < 0.05). At later hyperglycemia, the insulin response to GIP and GLP-1 was blunted to about one-third compared with controls (P < 0.05). In the bowel GLP-1 was about 2.6-16.7 times more potent than GIP in abolishing the migrating myoelectric complex in the GK and control rats. Polymerase chain reaction (PCR) showed GIP and GLP-1 receptor gene expression in pancreatic islets and in small bowel. The initially high, but later low insulin responsiveness to stimulation with GIP and GLP-1 along with inhibition of small bowel motility in the GK rat indicates a preserved incretin response on motility in diabetes type 2.
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Affiliation(s)
- T Edholm
- Department of Medicine, Gastroenterology Unit, Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden
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26
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Abstract
Pancreatic beta-cells possess an inherent ability to generate oscillatory signals that trigger insulin release. Coordination of the secretory activity among beta-cells results in pulsatile insulin secretion from the pancreas, which is considered important for the action of the hormone in the target tissues. This review focuses on the mechanisms underlying oscillatory control of insulin secretion at the level of the individual beta-cell. Recent studies have demonstrated that oscillations of the cytoplasmic Ca(2+) concentration are synchronized with oscillations in beta-cell metabolism, intracellular cAMP concentration, phospholipase C activity and plasma membrane phosphoinositide lipid concentrations. There are complex interdependencies between the different messengers and signalling pathways that contribute to amplitude regulation and shaping of the insulin secretory response to nutrient stimuli and neurohormonal modulators. Several of these pathways may be important pharmacological targets for improving pulsatile insulin secretion in type 2 diabetes.
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Affiliation(s)
- Anders Tengholm
- Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, SE-75123 Uppsala, Sweden.
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27
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Churchill EN, Qvit N, Mochly-Rosen D. Rationally designed peptide regulators of protein kinase C. Trends Endocrinol Metab 2009; 20:25-33. [PMID: 19056296 PMCID: PMC2714361 DOI: 10.1016/j.tem.2008.10.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/30/2008] [Accepted: 10/01/2008] [Indexed: 11/23/2022]
Abstract
Protein-protein interactions sequester enzymes close to their substrates. Protein kinase C (PKC) is one example of a ubiquitous signaling molecule with effects that are dependent upon localization. Short peptides derived from interaction sites between each PKC isozyme and its receptor for activated C kinase act as highly specific inhibitors and have become available as selective drugs in basic research and animal models of human diseases, such as myocardial infarction and hyperglycemia. Whereas the earlier inhibitory peptides are highly specific, we believe that peptides targeting additional interactions between PKC and selective substrates will generate even more selective tools that regulate different functions of individual isozymes. Here, we discuss the methodologies and applications for identifying selective regulators of PKC.
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Affiliation(s)
- Eric N Churchill
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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28
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Abstract
Beta-cells in pancreatic islets form complex syncytia. Sufficient cell-to-cell electrical coupling seems to ensure coordinated depolarization pattern and insulin release that can be further modulated by rich innervation. The complex structure and coordinated action develop after birth during fast proliferation of the endocrine tissue. These emergent properties can be lost due to various reasons later in life and can lead to glucose intolerance and diabetes mellitus. Pancreas slice is a novel method of choice to study the physiology of beta-cells still embedded in their normal cellulo-social context. I present major advantages, list drawbacks and provide an overview on recent advances in our understanding of the physiology of beta-cells using the pancreas slice approach.
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Affiliation(s)
- M Rupnik
- Faculty of Medicine, Institute of Physiology, University of Maribor, Maribor, Slovenia.
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29
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Biden TJ, Schmitz-Peiffer C, Burchfield JG, Gurisik E, Cantley J, Mitchell CJ, Carpenter L. The diverse roles of protein kinase C in pancreatic beta-cell function. Biochem Soc Trans 2008; 36:916-9. [PMID: 18793161 DOI: 10.1042/BST0360916] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Members of the serine/threonine PKC (protein kinase C) family perform diverse functions in multiple cell types. All members of the family are activated in signalling cascades triggered by occupation of cell surface receptors, but the cPKC (conventional PKC) and nPKC (novel PKC) isoforms are also responsive to fatty acid metabolites. PKC isoforms are involved in various aspects of pancreatic beta-cell function, including cell proliferation, differentiation and death, as well as regulation of secretion in response to glucose and muscarinic receptor agonists. Recently, the nPKC isoform, PKCepsilon, has also been implicated in the loss of insulin secretory responsiveness that underpins the development of Type 2 diabetes.
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30
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Schmitz-Peiffer C, Biden TJ. Protein kinase C function in muscle, liver, and beta-cells and its therapeutic implications for type 2 diabetes. Diabetes 2008; 57:1774-83. [PMID: 18586909 PMCID: PMC2453608 DOI: 10.2337/db07-1769] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 04/15/2008] [Indexed: 01/27/2023]
Affiliation(s)
| | - Trevor J. Biden
- From the Garvan Institute of Medical Research, Darlinghurst, Australia
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31
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Warwar N, Dov A, Abramovitch E, Wu R, Jmoudiak M, Haber E, Cerasi E, Nesher R. PKCepsilon mediates glucose-regulated insulin production in pancreatic beta-cells. Biochim Biophys Acta 2008; 1783:1929-34. [PMID: 18486624 DOI: 10.1016/j.bbamcr.2008.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 03/27/2008] [Accepted: 04/18/2008] [Indexed: 11/26/2022]
Abstract
Endocrine cells produce large amounts of one or more peptides. The post-translational control of selective production of a single protein is often unknown. We used 3 unrelated approaches to diminish PKCepsilon in rat islets to evaluate its role in preferential glucose-mediated insulin production. Transfection with siRNA (siR-PKCepsilon) or expression of inactive PKCepsilon (PKCepsilon-KD) resulted in a significant reduction in insulin response to glucose (16.7 mmol/l). Glucose stimulation resulted in concentration of PKCepsilon in the perinuclear region, an area known to be rich in ER-Golgi systems, associated with insulin-containing structures. ss'COP1 (RACK2) is the anchoring protein for PKCepsilon. Glucose-stimulated proinsulin production was diminished by 50% in islets expressing PKCepsilon-KD, and 60% in islets expressing RACK2 binding protein (epsilonV1-2); total protein biosynthesis was not affected. In islets expressing epsilonV1-2, a chase period following glucose stimulus resulted in a reduced proinsulin conversion to mature insulin. We propose that PKCepsilon plays a specific role in mediating the glucose-signal into insulin production: binding to ss'COP1 localizes the activated enzyme to the RER where it modulates the shuttling of proinsulin to the TGN. Subsequently the enzyme may be involved in anterograde trafficking of the prohormone or in its processing within the TGN.
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Affiliation(s)
- Nasim Warwar
- Endocrinology and Metabolism Service, Department of Medicine, The Hebrew University - Hadassah Medical Center, Jerusalem, Israel
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32
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Yanagita RC, Nakagawa Y, Yamanaka N, Kashiwagi K, Saito N, Irie K. Synthesis, conformational analysis, and biological evaluation of 1-hexylindolactam-V10 as a selective activator for novel protein kinase C isozymes. J Med Chem 2007; 51:46-56. [PMID: 18072722 DOI: 10.1021/jm0706719] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Conventional and novel protein kinase C (PKC) isozymes are the main targets of tumor promoters. We developed 1-hexylindolactam-V10 ( 5) as a selective activator for novel PKC isozymes that play important roles in various cellular processes related to tumor promotion, ischemia--reperfusion injury in the heart, and Alzheimer's disease. The compound existed as a mixture of three conformers. The trans-amide restricted analogues of 5 ( 14 and 15) hardly bound to PKC isozymes, suggesting that the active conformation of 5 could be that with a cis-amide. Compound 5 selectively translocated novel PKC isozymes over conventional PKC isozymes in HeLa cells at 0.1-1 microM. These results suggest that 5 could be useful for the functional analysis of novel PKC isozymes.
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Affiliation(s)
- Ryo C Yanagita
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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33
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Oyasu M, Fujimiya M, Kashiwagi K, Ohmori S, Imaeda H, Saito N. Immunogold electron microscopic demonstration of distinct submembranous localization of the activated gammaPKC depending on the stimulation. J Histochem Cytochem 2007; 56:253-65. [PMID: 18040079 DOI: 10.1369/jhc.7a7291.2007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We examined the precise intracellular translocation of gamma subtype of protein kinase C (gammaPKC) after various extracellular stimuli using confocal laser-scanning fluorescent microscopy (CLSM) and immunogold electron microscopy. By CLSM, treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in a slow and irreversible accumulation of green fluorescent protein (GFP)-tagged gammaPKC (gammaPKC-GFP) on the plasma membrane. In contrast, treatment with Ca(2+) ionophore and activation of purinergic or NMDA receptors induced a rapid and transient membrane translocation of gammaPKC-GFP. Although each stimulus resulted in PKC localization at the plasma membrane, electron microscopy revealed that gammaPKC showed a subtle but significantly different localization depending on stimulation. Whereas TPA and UTP induced a sustained localization of gammaPKC-GFP on the plasma membrane, Ca(2+) ionophore and NMDA rapidly translocated gammaPKC-GFP to the plasma membrane and then restricted gammaPKC-GFP in submembranous area (<500 nm from the plasma membrane). These results suggest that Ca(2+) influx alone induced the association of gammaPKC with the plasma membrane for only a moment and then located this enzyme at a proper distance in a touch-and-go manner, whereas diacylglycerol or TPA tightly anchored this enzyme on the plasma membrane. The distinct subcellular targeting of gammaPKC in response to various stimuli suggests a novel mechanism for PKC activation.
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Affiliation(s)
- Miho Oyasu
- Laboratory of Molecular Pharmacology, Biosignal Research Center, Kobe University, Kobe, Japan
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Vasavada RC, Wang L, Fujinaka Y, Takane KK, Rosa TC, Mellado-Gil JMD, Friedman PA, Garcia-Ocaña A. Protein kinase C-zeta activation markedly enhances beta-cell proliferation: an essential role in growth factor mediated beta-cell mitogenesis. Diabetes 2007; 56:2732-43. [PMID: 17686945 DOI: 10.2337/db07-0461] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Diabetes results from a deficiency of functional beta-cells. Previous studies have identified hepatocyte growth factor (HGF) and parathyroid hormone-related protein (PTHrP) as two potent beta-cell mitogens. The objective of this study is to determine 1) whether HGF and PTHrP have additive/synergistic effects on beta-cell growth and proliferation; 2) the signaling pathways through which these growth factors mediate beta-cell mitogenesis; and 3) whether activation of this/these signaling pathway(s) enhances human beta-cell replication. RESEARCH DESIGN AND METHODS We generated and phenotypically analyzed doubly transgenic mice overexpressing PTHrP and HGF in the beta-cell. INS-1 and primary mouse and human islet cells were used to identify mitogenic signaling pathways activated by HGF and/or PTHrP. RESULTS Combined overexpression of HGF and PTHrP in the beta-cell of doubly transgenic mice did not result in additive/synergistic effects on beta-cell growth and proliferation, suggesting potential cross-talk between signaling pathways activated by both growth factors. Examination of these signaling pathways in INS-1 cells revealed atypical protein kinase C (PKC) as a novel intracellular target activated by both HGF and PTHrP in beta-cells. Knockdown of PKC zeta, but not PKC iota/lambda, expression using specific small-interfering RNAs blocked growth factor-induced INS-1 cell proliferation. Furthermore, adenovirus-mediated delivery of kinase-dead PKC zeta completely inhibited beta-cell proliferation in primary islet cells overexpressing PTHrP and/or HGF. Finally, adenovirus-mediated delivery of constitutively active PKC zeta in mouse and human primary islet cells significantly enhanced beta-cell proliferation. CONCLUSIONS PKC zeta is essential for PTHrP- and HGF-induced beta-cell proliferation. PKC zeta activation could be useful in therapeutic strategies for expanding beta-cell mass in vitro and in vivo.
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Affiliation(s)
- Rupangi C Vasavada
- Department of Medicine, Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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35
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Abstract
Defective beta-cell function with resulting impairment of glucose-stimulated insulin release is a critical factor in the pathogenesis of type 2 diabetes. Accumulated studies in pancreatic islets of the spontaneously diabetic Goto-Kakizaki (GK) rat suggest that this is a useful animal model of type 2 diabetes. The GK rat is non-obese, and abnormal glucose regulation develops early in life in association with impaired insulin secretion. There are some differences in islet morphology and function reported between different GK rat colonies. In addition to reduction of beta-cell mass, a number of beta-cell defects have been described with possible relevance for the reduced insulin secretion. Interestingly, some of these defects have also been shown in isolated islets from type 2 diabetic humans. The polygenic nature of diabetes heredity in the GK rat may well resemble the genetic basis in the majority of patients with type 2 diabetes. Here, we review studies concerning beta-cell function and islet gene expression in the GK rat and compare it with the limited number of investigations on similar topics in isolated islets from patients with type 2 diabetes.
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Affiliation(s)
- C-G Ostenson
- Department of Molecular Medicine and Surgery, Endocrine and Diabetes Unit, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
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36
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Nunes E, Peixoto F, Louro T, Sena CM, Santos MS, Matafome P, Moreira PI, Seiça R. Soybean oil treatment impairs glucose-stimulated insulin secretion and changes fatty acid composition of normal and diabetic islets. Acta Diabetol 2007; 44:121-30. [PMID: 17721750 DOI: 10.1007/s00592-007-0252-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 03/19/2007] [Indexed: 10/22/2022]
Abstract
We investigated the effect of sub-chronic soybean oil (SO) treatment on the insulin secretion and fatty acid composition of islets of Langerhans obtained from Goto-Kakizaki (GK), a model of type 2 diabetes, and normal Wistar rats. We observed that soybean-treated Wistar rats present insulin resistance and defective islet insulin secretion when compared with untreated Wistar rats. The decrease in insulin secretion occurred at all concentrations of glucose and arginine tested. Furthermore we observed that soybean-treated normal islets present a significant decrease in two saturated fatty acids, myristic and heneicosanoic acids, and one monounsaturated eicosenoic acid, and the appearance of the monounsaturated erucic acid. Concerning diabetic animals, we observed that soybean-treated diabetic rats, when compared with untreated GK rats, present an increase in plasma non-fasting free fatty acids, an exacerbation of islet insulin secretion impairment in all conditions tested and a significant decrease in the monounsaturated palmitoleic acid. Altogether our results show that SO treatment results in a decrease of insulin secretion and alterations on fatty acid composition in normal and diabetic islets. Furthermore, the impairment of insulin secretion, islet erucic acid and fasting plasma insulin levels are similar in treated normal and untreated diabetic rats, suggesting that SO could have a deleterious effect on beta-cell function and insulin sensitivity.
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Affiliation(s)
- E Nunes
- Faculty of Medicine, Institute of Physiology, Rua Larga, PT-3004-504, Coimbra, Portugal
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Abstract
The Goto Kakizaki (GK) rat is a widely used animal model to study defective glucose-stimulated insulin release in type-2 diabetes (T2D). As in T2D patients, the expression of several proteins involved in Ca(2+)-dependent exocytosis of insulin-containing large dense-core vesicles is dysregulated in this model. So far, a defect in late steps of insulin secretion could not be demonstrated. To resolve this apparent contradiction, we studied Ca(2+)-secretion coupling of healthy and GK rat beta cells in acute pancreatic tissue slices by assessing exocytosis with high time-resolution membrane capacitance measurements. We found that beta cells of GK rats respond to glucose stimulation with a normal increase in the cytosolic Ca(2+) concentration. During trains of depolarizing pulses, the secretory activity from GK rat beta cells was defective in spite of upregulated cell size and doubled voltage-activated Ca(2+) currents. In GK rat beta cells, evoked Ca(2+) entry was significantly less efficient in triggering release than in nondiabetic controls. This impairment was neither due to a decrease of functional vesicle pool sizes nor due to different kinetics of pool refilling. Strong stimulation with two successive trains of depolarizing pulses led to a prominent activity-dependent facilitation of release in GK rat beta cells, whereas secretion in controls was unaffected. Broad-spectrum inhibition of PKC sensitized Ca(2+)-dependent exocytosis, whereas it prevented the activity-dependent facilitation in GK rat beta cells. We conclude that a decrease in the sensitivity of the GK rat beta-cell to depolarization-evoked Ca(2+) influx is involved in defective glucose-stimulated insulin secretion. Furthermore, we discuss a role for constitutively increased activity of one or more PKC isoenzymes in diabetic rat beta cells.
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Affiliation(s)
- Tobias Rose
- European Neuroscience Institute-Göttingen, 37073 Göttingen, Germany
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Uchida T, Iwashita N, Ohara-Imaizumi M, Ogihara T, Nagai S, Choi JB, Tamura Y, Tada N, Kawamori R, Nakayama KI, Nagamatsu S, Watada H. Protein Kinase Cδ Plays a Non-redundant Role in Insulin Secretion in Pancreatic β Cells. J Biol Chem 2007; 282:2707-16. [PMID: 17135234 DOI: 10.1074/jbc.m610482200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein kinase C (PKC) is considered to modulate glucose-stimulated insulin secretion. Pancreatic beta cells express multiple isoforms of PKCs; however, the role of each isoform in glucose-stimulated insulin secretion remains controversial. In this study we investigated the role of PKCdelta, a major isoform expressed in pancreatic beta cells on beta cell function. Here, we showed that PKCdelta null mice manifested glucose intolerance with impaired insulin secretion. Insulin tolerance test showed no decrease in insulin sensitivity in PKCdelta null mice. Studies using islets isolated from these mice demonstrated decreased glucose- and KCl-stimulated insulin secretion. Perifusion studies indicated that mainly the second phase of insulin secretion was decreased. On the other hand, glucose-induced influx of Ca2+ into beta cells was not altered. Immunohistochemistry using total internal reflection fluorescence microscopy and electron microscopic analysis showed an increased number of insulin granules close to the plasma membrane in beta cells of PKCdelta null mice. Although PKC is thought to phosphorylate Munc18-1 and facilitate soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors complex formation, the phosphorylation of Munc18-1 by glucose stimulation was decreased in islets of PKCdelta null mice. We conclude that PKCdelta plays a non-redundant role in glucose-stimulated insulin secretion. The impaired insulin secretion in PKCdelta null mice is associated with reduced phosphorylation of Munc18-1.
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Affiliation(s)
- Toyoyoshi Uchida
- Department of Medicine, Metabolism and Endocrinology, Juntendo University School of Medicine, 2-1-1, Tokyo 113-8421, Japan
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