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Deręgowska A, Tomaszek N, Cuch P, Kozioł K, Kaniuka O, Sabadashka M, Bandura Y, Sybirna N. Glucotoxicity is mediated by cytoplasmic distribution of RAP1 in pancreatic β-cells. Arch Biochem Biophys 2024; 755:109982. [PMID: 38570110 DOI: 10.1016/j.abb.2024.109982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 03/04/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024]
Abstract
Diabetes mellitus (DM) is a group of chronic metabolic disorders characterized by persistent hyperglycemia. In our study, we analyzed the level and location of RAP1 changes in the development of β-cell dysfunction induced by glucotoxicity. We employed three pancreatic β-cell lines, namely INS-1, 1.2B4, and NIT-1, as well as a streptozotocin-induced diabetes rat model. We demonstrate that after high glucose treatment, RAP1 is increased, probably through induction by AKT, allowing RAP1 to shuttle from the nucleus to the cytoplasm and activate NF-κB signaling. Furthermore, non-enzymatic post-translational modifications of RAP1, such as advanced glycation end products and carbonylation may affect the function of RAP1, such as activation of the NF-κB signaling. Taken together, we showed that RAP1 is a new player in the mechanism of glucotoxicity in pancreatic β-cells.
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Affiliation(s)
- A Deręgowska
- Institute of Biotechnology, College of Natural Sciences, University of Rzeszow, Pigonia 1, 35-310, Rzeszow, Poland.
| | - N Tomaszek
- Institute of Biotechnology, College of Natural Sciences, University of Rzeszow, Pigonia 1, 35-310, Rzeszow, Poland
| | - P Cuch
- Institute of Biotechnology, College of Natural Sciences, University of Rzeszow, Pigonia 1, 35-310, Rzeszow, Poland
| | - K Kozioł
- Institute of Biotechnology, College of Natural Sciences, University of Rzeszow, Pigonia 1, 35-310, Rzeszow, Poland
| | - O Kaniuka
- Department of Biochemistry, Ivan Franko National University of Lviv, 1, Universytetska St., 79000, Lviv, Ukraine
| | - M Sabadashka
- Department of Biochemistry, Ivan Franko National University of Lviv, 1, Universytetska St., 79000, Lviv, Ukraine
| | - Yu Bandura
- Department of Biochemistry, Ivan Franko National University of Lviv, 1, Universytetska St., 79000, Lviv, Ukraine
| | - N Sybirna
- Department of Biochemistry, Ivan Franko National University of Lviv, 1, Universytetska St., 79000, Lviv, Ukraine
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2
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Chen X, Zhang Z, Niu H, Tian X, Tian H, Yao W, He H, Shi H, Li C, Luo J. Goat Milk Improves Glucose Metabolism in Type 2 Diabetic Mice and Protects Pancreatic β-Cell Functions. Mol Nutr Food Res 2024; 68:e2200842. [PMID: 37990402 DOI: 10.1002/mnfr.202200842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 07/13/2023] [Indexed: 11/23/2023]
Abstract
SCOPE Consuming goat milk is known to benefit high-fat diet-fed and streptozocin (STZ)-induced diabetic rats, but the underlying mechanisms are unknown. This study is conducted to investigate the metabolic effects of a goat milk diet (a form of goat milk powder) on glucose homeostasis and pancreatic conditions in a mouse model of Type 2 diabetes mellitus (T2DM) induced by STZ. METHODS AND RESULTS T2DM mice are fed with a goat-milk-based diet containing 10.3% w/w goat milk powder for 10 weeks for investigating the in vivo effects; a β-cell line MIN6 cells are used to test the in vitro effects of digested goat milk (DGM). Goat milk diet improves the deleterious effects of STZ on fasting glucose levels and glucose tolerance, accelerates pancreatic structure recovery, and alters blood metabolites in mice. Based on the significant differences observed in metabolites, the key pathways, metabolite regulatory enzymes, metabolite molecular modules, and biochemical reactions are identified as critical integrated pathways. DGM promotes the cell activity, glucose transportation, and AKT activation in cultured STZ-treated MIN6 cells in vitro. CONCLUSIONS Goat milk diet improves glucose homeostasis and pancreatic conditions of T2DM mice, in association with improved blood metabolite profiles and activation of pancreatic AKT pathway.
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Affiliation(s)
- Xiaoying Chen
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Zhifei Zhang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Huiming Niu
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xinmiao Tian
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Huibin Tian
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Weiwei Yao
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Huanshan He
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Huaiping Shi
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Cong Li
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Jun Luo
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
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Ferreira G, Santander A, Cardozo R, Chavarría L, Domínguez L, Mujica N, Benítez M, Sastre S, Sobrevia L, Nicolson GL. Nutrigenomics of inward rectifier potassium channels. Biochim Biophys Acta Mol Basis Dis 2023:166803. [PMID: 37406972 DOI: 10.1016/j.bbadis.2023.166803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/27/2023] [Accepted: 06/30/2023] [Indexed: 07/07/2023]
Abstract
Inwardly rectifying potassium (Kir) channels play a key role in maintaining the resting membrane potential and supporting potassium homeostasis. There are many variants of Kir channels, which are usually tetramers in which the main subunit has two trans-membrane helices attached to two N- and C-terminal cytoplasmic tails with a pore-forming loop in between that contains the selectivity filter. These channels have domains that are strongly modulated by molecules present in nutrients found in different diets, such as phosphoinositols, polyamines and Mg2+. These molecules can impact these channels directly or indirectly, either allosterically by modulation of enzymes or via the regulation of channel expression. A particular type of these channels is coupled to cell metabolism and inhibited by ATP (KATP channels, essential for insulin release and for the pathogenesis of metabolic diseases like diabetes mellitus). Genomic changes in Kir channels have a significant impact on metabolism, such as conditioning the nutrients and electrolytes that an individual can take. Thus, the nutrigenomics of ion channels is an important emerging field in which we are attempting to understand how nutrients and diets can affect the activity and expression of ion channels and how genomic changes in such channels may be the basis for pathological conditions that limit nutrition and electrolyte intake. In this contribution we briefly review Kir channels, discuss their nutrigenomics, characterize how different components in the diet affect their function and expression, and suggest how their genomic changes lead to pathological phenotypes that affect diet and electrolyte intake.
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Affiliation(s)
- Gonzalo Ferreira
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay.
| | - Axel Santander
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Romina Cardozo
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Luisina Chavarría
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Lucía Domínguez
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Nicolás Mujica
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Milagros Benítez
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay
| | - Santiago Sastre
- Laboratory of Ion Channels, Biological Membranes and Cell Signaling, Dept. of Biophysics, Facultad de Medicina, CP 11800, Universidad de la Republica, Montevideo, Uruguay; Centro de Investigaciones Biomédicas (CEINBIO), Universidad de la República, Montevideo CP 11800, Uruguay
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL), Department of Obstetrics, Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile; Department of Physiology, Faculty of Pharmacy, Universidad de Sevilla, Seville E-41012, Spain; Medical School (Faculty of Medicine), Sao Paulo State University (UNESP), Brazil; University of Queensland, Centre for Clinical Research (UQCCR), Faculty of Medicine and Biomedical Sciences, University of Queensland, Herston, 4029, Queensland, Australia; Tecnologico de Monterrey, Eutra, The Institute for Obesity Research (IOR), School of Medicine and Health Sciences, Monterrey, Nuevo León, Mexico
| | - Garth L Nicolson
- Department of Molecular Pathology, The Institute for Molecular Medicine, Huntington Beach, CA, USA
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4
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Mu-U-Min RBA, Diane A, Allouch A, Al-Siddiqi HH. Ca 2+-Mediated Signaling Pathways: A Promising Target for the Successful Generation of Mature and Functional Stem Cell-Derived Pancreatic Beta Cells In Vitro. Biomedicines 2023; 11:1577. [PMID: 37371672 DOI: 10.3390/biomedicines11061577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/18/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
Diabetes mellitus is a chronic disease affecting over 500 million adults globally and is mainly categorized as type 1 diabetes mellitus (T1DM), where pancreatic beta cells are destroyed, and type 2 diabetes mellitus (T2DM), characterized by beta cell dysfunction. This review highlights the importance of the divalent cation calcium (Ca2+) and its associated signaling pathways in the proper functioning of beta cells and underlines the effects of Ca2+ dysfunction on beta cell function and its implications for the onset of diabetes. Great interest and promise are held by human pluripotent stem cell (hPSC) technology to generate functional pancreatic beta cells from diabetic patient-derived stem cells to replace the dysfunctional cells, thereby compensating for insulin deficiency and reducing the comorbidities of the disease and its associated financial and social burden on the patient and society. Beta-like cells generated by most current differentiation protocols have blunted functionality compared to their adult human counterparts. The Ca2+ dynamics in stem cell-derived beta-like cells and adult beta cells are summarized in this review, revealing the importance of proper Ca2+ homeostasis in beta-cell function. Consequently, the importance of targeting Ca2+ function in differentiation protocols is suggested to improve current strategies to use hPSCs to generate mature and functional beta-like cells with a comparable glucose-stimulated insulin secretion (GSIS) profile to adult beta cells.
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Affiliation(s)
- Razik Bin Abdul Mu-U-Min
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Abdoulaye Diane
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Asma Allouch
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
| | - Heba H Al-Siddiqi
- Diabetes Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation (QF), Doha P.O. Box 34110, Qatar
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5
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Conway JRW, Warren SC, Lee YK, McCulloch AT, Magenau A, Lee V, Metcalf XL, Stoehr J, Haigh K, Abdulkhalek L, Guaman CS, Reed DA, Murphy KJ, Pereira BA, Mélénec P, Chambers C, Latham SL, Lenthall H, Deenick EK, Ma Y, Phan T, Lim E, Joshua AM, Walters S, Grey ST, Shi YC, Zhang L, Herzog H, Croucher DR, Philp A, Scheele CLGJ, Herrmann D, Sansom OJ, Morton JP, Papa A, Haigh JJ, Nobis M, Timpson P. Monitoring AKT activity and targeting in live tissue and disease contexts using a real-time Akt-FRET biosensor mouse. SCIENCE ADVANCES 2023; 9:eadf9063. [PMID: 37126544 PMCID: PMC10132756 DOI: 10.1126/sciadv.adf9063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Aberrant AKT activation occurs in a number of cancers, metabolic syndrome, and immune disorders, making it an important target for the treatment of many diseases. To monitor spatial and temporal AKT activity in a live setting, we generated an Akt-FRET biosensor mouse that allows longitudinal assessment of AKT activity using intravital imaging in conjunction with image stabilization and optical window technology. We demonstrate the sensitivity of the Akt-FRET biosensor mouse using various cancer models and verify its suitability to monitor response to drug targeting in spheroid and organotypic models. We also show that the dynamics of AKT activation can be monitored in real time in diverse tissues, including in individual islets of the pancreas, in the brown and white adipose tissue, and in the skeletal muscle. Thus, the Akt-FRET biosensor mouse provides an important tool to study AKT dynamics in live tissue contexts and has broad preclinical applications.
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Affiliation(s)
- James R W Conway
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, FI-20520 Turku, Finland
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Sean C Warren
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Young-Kyung Lee
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Andrew T McCulloch
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- School of Clinical Medicine, UNSW Sydney, Randwick Clinical Campus, Sydney, NSW, Australia
| | - Astrid Magenau
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Victoria Lee
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Xanthe L Metcalf
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Janett Stoehr
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Katharina Haigh
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- CancerCare Manitoba Research Institute, Winnipeg, Manitoba, Canada
| | - Lea Abdulkhalek
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Cristian S Guaman
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Daniel A Reed
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Kendelle J Murphy
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Brooke A Pereira
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Pauline Mélénec
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Cecilia Chambers
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Sharissa L Latham
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Helen Lenthall
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
| | - Elissa K Deenick
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Yuanqing Ma
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Tri Phan
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Elgene Lim
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Anthony M Joshua
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Stacey Walters
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
| | - Shane T Grey
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Yan-Chuan Shi
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Lei Zhang
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - Herbert Herzog
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
| | - David R Croucher
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Andy Philp
- School of Clinical Medicine, Randwick Clinical Campus, UNSW Sydney, Centre for Healthy Ageing, Centenary Institute, Missenden Road, Sydney, NSW 2050, Australia
- Charles Perkins Centre, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia
| | - Colinda L G J Scheele
- Laboratory for Intravital Imaging and Dynamics of Tumor Progression, VIB Center for Cancer Biology, KU Leuven, 3000 Leuven, Belgium
- Department of Oncology, KU Leuven, 3000 Leuven, Belgium
| | - David Herrmann
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Owen J Sansom
- Cancer Research UK Beatson Institute, Glasgow G611BD, UK
- School of Cancer Sciences, Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, University of Glasgow, Glasgow G611QH, UK
| | - Jennifer P Morton
- Cancer Research UK Beatson Institute, Glasgow G611BD, UK
- School of Cancer Sciences, Wolfson Wohl Cancer Research Centre, Institute of Cancer Sciences, University of Glasgow, Glasgow G611QH, UK
| | - Antonella Papa
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Jody J Haigh
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
- CancerCare Manitoba Research Institute, Winnipeg, Manitoba, Canada
| | - Max Nobis
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
- Laboratory for Intravital Imaging and Dynamics of Tumor Progression, VIB Center for Cancer Biology, KU Leuven, 3000 Leuven, Belgium
- Intravital Imaging Expertise Center, VIB Center for Cancer Biology, KU Leuven, 3000 Leuven, Belgium
| | - Paul Timpson
- Garvan Institute of Medical Research & The Kinghorn Cancer Centre, Sydney, NSW 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, Sydney, NSW 2010, Australia
- Cancer Ecosystems Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
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6
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Rosa LRDO, Vettorazzi JF, Zangerolamo L, Carneiro EM, Barbosa HCDL. TUDCA receptors and their role on pancreatic beta cells. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 167:26-31. [PMID: 34547326 DOI: 10.1016/j.pbiomolbio.2021.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 08/31/2021] [Accepted: 09/14/2021] [Indexed: 12/12/2022]
Abstract
Bile acids have received increasing attention over the past years as their multiple alternative roles became clearer. Tauroursodeoxycholic Acid (TUDCA) in specific has generated special interest due to its ability to promote pancreatic survival and function, as well as reduce endoplasmic reticulum stress. However, there are few studies explaining the molecular mechanisms behind TUDCA's beneficial actions on pancreatic beta cells. In this review, we decided to review the literature in order to craft a primer for researchers on what is known about TUDCA's receptors and the molecular pathways involved in this bile acid's function in the endocrine pancreas. We review the studies that focused on G protein-coupled bile acid receptor (TGR5), Sphingosine-1-phosphate receptor 2 (S1PR2) and α5β1 Integrin function in pancreatic cells. Our hope is to provide a basis for future studies to expand upon, especially considering the current lack of studies focusing on the importance of these receptors, either through TUDCA signaling or other signaling molecules.
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Affiliation(s)
- Lucas Rodolfo de Oliveira Rosa
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | | | - Lucas Zangerolamo
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Everardo Magalhães Carneiro
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
| | - Helena Cristina de Lima Barbosa
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
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7
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Untereiner A, Xu J, Bhattacharjee A, Cabrera O, Hu C, Dai FF, Wheeler MB. γ-aminobutyric acid stimulates β-cell proliferation through the mTORC1/p70S6K pathway, an effect amplified by Ly49, a novel γ-aminobutyric acid type A receptor positive allosteric modulator. Diabetes Obes Metab 2020; 22:2021-2031. [PMID: 32558194 DOI: 10.1111/dom.14118] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/11/2020] [Accepted: 06/14/2020] [Indexed: 12/15/2022]
Abstract
AIM To examine the mechanism of action of γ-aminobutyric acid (GABA) on β-cell proliferation and investigate if co-treatment with Ly49, a novel GABA type A receptor positive allosteric modulator (GABAA -R PAM), amplifies this effect. METHODS Human or mouse islets were co-treated for 4-5 days with GABA and selected receptor or cell signalling pathway modulators. Immunofluorescence was used to determine protein co-localization, cell number or proliferation, and islet size. Osmotic minipumps were surgically implanted in mice to assess Ly49 effects on pancreatic β-cells. RESULTS Amplification of GABAA -R signalling enhanced GABA-stimulated β-cell proliferation in cultured mouse islets. Co-treatment of GABA with an inhibitor specific for PI3K, mTORC1/2, or p70S6K, abolished GABA-stimulated β-cell proliferation in mouse and human islets. Nuclear p-AktSer473 and p-p70S6KThr421/Ser424 expression in pancreatic β-cells was increased in GABA-treated mice compared with vehicle-treated mice, an effect augmented with GABA and Ly49 co-treatment. Mice co-treated with GABA and Ly49 exhibited enhanced β-cell area and proliferation compared with GABA-treated mice. Furthermore, S961 injection (an insulin receptor antagonist) resulted in enhanced plasma insulin in GABA and Ly49 co-treated mice compared with GABA-treated mice. Importantly, GABA co-treated with Ly49 increased β-cell proliferation in human islets providing a potential application for human subjects. CONCLUSIONS We show that GABA stimulates β-cell proliferation via the PI3K/mTORC1/p70S6K pathway in both mouse and human islets. Furthermore, we show that Ly49 enhances the β-cell regenerative effects of GABA, showing potential in the intervention of diabetes.
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Affiliation(s)
- Ashley Untereiner
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Jie Xu
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Key Clinical Center for Metabolic Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Alpana Bhattacharjee
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Over Cabrera
- Diabetes and Complications Research, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, USA
| | - Cheng Hu
- Shanghai Diabetes Institute, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Key Clinical Center for Metabolic Diseases, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
- Institute for Metabolic Disease, Fengxian Central Hospital Affiliated to Southern Medical University, Shanghai, China
| | - Feihan F Dai
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Michael B Wheeler
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
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Ye L, Li G, Goebel A, Raju AV, Kong F, Lv Y, Li K, Zhu Y, Raja S, He P, Li F, Mwangi SM, Hu W, Srinivasan S. Caspase-11-mediated enteric neuronal pyroptosis underlies Western diet-induced colonic dysmotility. J Clin Invest 2020; 130:3621-3636. [PMID: 32484462 PMCID: PMC7324173 DOI: 10.1172/jci130176] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 03/24/2020] [Indexed: 02/06/2023] Open
Abstract
Enteric neuronal degeneration, as seen in inflammatory bowel disease, obesity, and diabetes, can lead to gastrointestinal dysmotility. Pyroptosis is a novel form of programmed cell death but little is known about its role in enteric neuronal degeneration. We observed higher levels of cleaved caspase-1, a marker of pyroptosis, in myenteric ganglia of overweight and obese human subjects compared with normal-weight subjects. Western diet-fed (WD-fed) mice exhibited increased myenteric neuronal pyroptosis, delayed colonic transit, and impaired electric field stimulation-induced colonic relaxation responses. WD increased TLR4 expression and cleaved caspase-1 in myenteric nitrergic neurons. Overactivation of nitrergic neuronal NF-κB signaling resulted in increased pyroptosis and delayed colonic motility. In caspase-11-deficient mice, WD did not induce nitrergic myenteric neuronal pyroptosis and colonic dysmotility. To understand the contributions of saturated fatty acids and bacterial products to the steps leading to enteric neurodegeneration, we performed in vitro experiments using mouse enteric neurons. Palmitate and lipopolysaccharide (LPS) increased nitrergic, but not cholinergic, enteric neuronal pyroptosis. LPS gained entry to the cytosol in the presence of palmitate, activating caspase-11 and gasdermin D, leading to pyroptosis. These results support a role of the caspase-11-mediated pyroptotic pathway in WD-induced myenteric nitrergic neuronal degeneration and colonic dysmotility, providing important therapeutic targets for enteric neuropathy.
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Affiliation(s)
- Lan Ye
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Gastroenterology Research, Atlanta VA Health Care System, Decatur, Georgia, USA
| | - Ge Li
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Gastroenterology Research, Atlanta VA Health Care System, Decatur, Georgia, USA
| | - Anna Goebel
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Gastroenterology Research, Atlanta VA Health Care System, Decatur, Georgia, USA
| | - Abhinav V. Raju
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Gastroenterology Research, Atlanta VA Health Care System, Decatur, Georgia, USA
| | - Feng Kong
- Second Hospital of Shandong University, Jinan, China
| | - Yanfei Lv
- Second Hospital of Shandong University, Jinan, China
| | - Kailin Li
- Second Hospital of Shandong University, Jinan, China
| | - Yuanjun Zhu
- Center for Metabolic Disease Research, Department of Pathology and Laboratory Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Shreya Raja
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Gastroenterology Research, Atlanta VA Health Care System, Decatur, Georgia, USA
| | - Peijian He
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Fang Li
- Center for Metabolic Disease Research, Department of Pathology and Laboratory Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Simon Musyoka Mwangi
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Gastroenterology Research, Atlanta VA Health Care System, Decatur, Georgia, USA
| | - Wenhui Hu
- Center for Metabolic Disease Research, Department of Pathology and Laboratory Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Shanthi Srinivasan
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
- Gastroenterology Research, Atlanta VA Health Care System, Decatur, Georgia, USA
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9
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Jara MA, Werneck-De-Castro JP, Lubaczeuski C, Johnson JD, Bernal-Mizrachi E. Pancreatic and duodenal homeobox-1 (PDX1) contributes to β-cell mass expansion and proliferation induced by Akt/PKB pathway. Islets 2020; 12:32-40. [PMID: 32876522 PMCID: PMC7527019 DOI: 10.1080/19382014.2020.1762471] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Maintenance of pancreatic β-cell mass and function is fundamental to glucose homeostasis and to prevent diabetes. The PI3 K-Akt-mTORC1 pathway is critical for β-cells mass and function, while PDX1 has been implicated in β-cell development, maturation, and function. Here we tested whether Akt signaling requires PDX1 expression to regulate β-cell mass, proliferation, and glucose homeostasis. In order to address that, we crossed a mouse model overexpressing constitutively active Akt mutant in β-cells (β-caAkt) with mice lacking one allele of PDX1gene (β-caAkt/pdx1+/-). While the β-caAkt mice exhibit higher plasma insulin levels, greater β-cell mass and improved glucose tolerance compared to control mice, the β-caAkt/pdx1+/- mice are hyperglycemic and intolerant to glucose. The changes in glucose homeostasis in β-caAkt/pdx1+/- were associated with a 60% reduction in β-cell mass compared to β-caAkt mice. The impaired β-cell mass in the β-caAkt/pdx1+/- mice can be explained by a lesser β-cell proliferation measured by the number of Ki67 positive β-cells. We did not observe any differences in apoptosis between β-caAkt/pdx1+/- and β-caAkt mice. In conclusion, PDX1 contributes to β-cell mass expansion and glucose metabolism induced by activation of Akt signaling.
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Affiliation(s)
- Mark Anthony Jara
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Joao Pedro Werneck-De-Castro
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
- Miami VA Health Care System, Miami, FL, USA
| | - Camila Lubaczeuski
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - James D. Johnson
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
- Miami VA Health Care System, Miami, FL, USA
- CONTACT Ernesto Bernal-Mizrachi Department Of Internal Medicine, Division Of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL33136, USA
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10
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Calcium Signaling in ß-cell Physiology and Pathology: A Revisit. Int J Mol Sci 2019; 20:ijms20246110. [PMID: 31817135 PMCID: PMC6940736 DOI: 10.3390/ijms20246110] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 11/28/2019] [Accepted: 12/02/2019] [Indexed: 12/12/2022] Open
Abstract
Pancreatic beta (β) cell dysfunction results in compromised insulin release and, thus, failed regulation of blood glucose levels. This forms the backbone of the development of diabetes mellitus (DM), a disease that affects a significant portion of the global adult population. Physiological calcium (Ca2+) signaling has been found to be vital for the proper insulin-releasing function of β-cells. Calcium dysregulation events can have a dramatic effect on the proper functioning of the pancreatic β-cells. The current review discusses the role of calcium signaling in health and disease in pancreatic β-cells and provides an in-depth look into the potential role of alterations in β-cell Ca2+ homeostasis and signaling in the development of diabetes and highlights recent work that introduced the current theories on the connection between calcium and the onset of diabetes.
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11
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Oakie A, Feng ZC, Li J, Silverstein J, Yee SP, Wang R. Long-term c-Kit overexpression in beta cells compromises their function in ageing mice. Diabetologia 2019; 62:1430-1444. [PMID: 31154478 DOI: 10.1007/s00125-019-4890-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 04/04/2019] [Indexed: 12/23/2022]
Abstract
AIMS/HYPOTHESIS c-Kit signalling regulates intracellular pathways that enhance beta cell proliferation, insulin secretion and islet vascularisation in mice up to 28 weeks of age and on short-term high-fat diet. However, long-term c-Kit activation in ageing mouse islets has yet to be examined. This study utilises beta cell-specific c-Kit-overexpressing transgenic (c-KitβTg) ageing mice (~60 weeks) to determine the effect of its activation on beta cell dysfunction and insulin secretion. METHODS Wild-type and c-KitβTg mice, aged 60 weeks, were examined using metabolic tests to determine glucose tolerance and insulin secretion. Pancreas histology and proteins in isolated islets were examined to determine the expression of beta cell transcription factors, proliferation and intracellular signalling. To determine the role of insulin receptor signalling in ageing c-KitβTg mice, we generated beta cell-specific inducible insulin receptor knockout in ageing c-KitβTg mice (c-KitβTg;βIRKO mice) and examined the ageing mice for glucose tolerance and islet histology. RESULTS Ageing c-KitβTg mice progressively developed glucose intolerance, compared with age-matched wild-type littermates, due to impaired insulin secretion. Increased beta cell mass, proliferation and nuclear forkhead box transcription factor O1 (FOXO1) expression and reduced exocytotic protein levels were detected in ageing c-KitβTg mouse islets. Protein analyses of isolated islets showed increased insulin receptor, phosphorylated IRS-1Ser612 and cleaved poly(ADP-ribose) polymerase levels in ageing c-KitβTg mice. Ageing c-KitβTg mouse islets treated ex vivo with insulin demonstrated reduced Akt phosphorylation, indicating that prolonged c-Kit induced beta cell insulin insensitivity. Ageing c-KitβTg;βIRKO mice displayed improved glucose tolerance and beta cell function compared with ageing c-KitβTg mice. CONCLUSIONS/INTERPRETATION These findings indicate that long-term c-Kit overexpression in beta cells has a negative impact on insulin exocytosis and that temporally dependent regulation of c-Kit-insulin receptor signalling is important for optimal beta cell function.
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Affiliation(s)
- Amanda Oakie
- Children's Health Research Institute, University of Western Ontario, Victoria Research Laboratories, Room A5-140, 800 Commissioners Road East, London, ON, N6C 2V5, Canada
- Department of Pathology and Laboratory Medicine, University of Western Ontario, London, ON, Canada
| | - Zhi-Chao Feng
- Children's Health Research Institute, University of Western Ontario, Victoria Research Laboratories, Room A5-140, 800 Commissioners Road East, London, ON, N6C 2V5, Canada
| | - Jinming Li
- Children's Health Research Institute, University of Western Ontario, Victoria Research Laboratories, Room A5-140, 800 Commissioners Road East, London, ON, N6C 2V5, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - Jenna Silverstein
- Children's Health Research Institute, University of Western Ontario, Victoria Research Laboratories, Room A5-140, 800 Commissioners Road East, London, ON, N6C 2V5, Canada
| | - Siu-Pok Yee
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT, USA
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, USA
| | - Rennian Wang
- Children's Health Research Institute, University of Western Ontario, Victoria Research Laboratories, Room A5-140, 800 Commissioners Road East, London, ON, N6C 2V5, Canada.
- Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada.
- Department of Medicine, University of Western Ontario, London, ON, Canada.
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12
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Sabatini PV, Speckmann T, Lynn FC. Friend and foe: β-cell Ca 2+ signaling and the development of diabetes. Mol Metab 2019; 21:1-12. [PMID: 30630689 PMCID: PMC6407368 DOI: 10.1016/j.molmet.2018.12.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/03/2018] [Accepted: 12/19/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The divalent cation Calcium (Ca2+) regulates a wide range of processes in disparate cell types. Within insulin-producing β-cells, increases in cytosolic Ca2+ directly stimulate insulin vesicle exocytosis, but also initiate multiple signaling pathways. Mediated through activation of downstream kinases and transcription factors, Ca2+-regulated signaling pathways leverage substantial influence on a number of critical cellular processes within the β-cell. Additionally, there is evidence that prolonged activation of these same pathways is detrimental to β-cell health and may contribute to Type 2 Diabetes pathogenesis. SCOPE OF REVIEW This review aims to briefly highlight canonical Ca2+ signaling pathways in β-cells and how β-cells regulate the movement of Ca2+ across numerous organelles and microdomains. As a main focus, this review synthesizes experimental data from in vitro and in vivo models on both the beneficial and detrimental effects of Ca2+ signaling pathways for β-cell function and health. MAJOR CONCLUSIONS Acute increases in intracellular Ca2+ stimulate a number of signaling cascades, resulting in (de-)phosphorylation events and activation of downstream transcription factors. The short-term stimulation of these Ca2+ signaling pathways promotes numerous cellular processes critical to β-cell function, including increased viability, replication, and insulin production and secretion. Conversely, chronic stimulation of Ca2+ signaling pathways increases β-cell ER stress and results in the loss of β-cell differentiation status. Together, decades of study demonstrate that Ca2+ movement is tightly regulated within the β-cell, which is at least partially due to its dual roles as a potent signaling molecule.
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Affiliation(s)
- Paul V Sabatini
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada; Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Thilo Speckmann
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Francis C Lynn
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
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13
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Murase M, Seino Y, Maekawa R, Iida A, Hosokawa K, Hayami T, Tsunekawa S, Hamada Y, Yokoi N, Seino S, Hayashi Y, Arima H. Functional adenosine triphosphate-sensitive potassium channel is required in high-carbohydrate diet-induced increase in β-cell mass. J Diabetes Investig 2019; 10:238-250. [PMID: 30084544 PMCID: PMC6400177 DOI: 10.1111/jdi.12907] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/26/2018] [Accepted: 08/01/2018] [Indexed: 12/22/2022] Open
Abstract
AIMS/INTRODUCTION A high-carbohydrate diet is known to increase insulin secretion and induce obesity. However, whether or not a high-carbohydrate diet affects β-cell mass (BCM) has been little investigated. MATERIALS AND METHODS Both wild-type (WT) mice and adenosine triphosphate-sensitive potassium channel-deficient (Kir6.2KO) mice were fed normal chow or high-starch (ST) diets for 22 weeks. BCM and the numbers of islets were analyzed by immunohistochemistry, and gene expression levels in islets were investigated by quantitative real-time reverse transcription polymerase chain reaction. MIN6-K8 β-cells were stimulated in solution containing various concentrations of glucose combined with nifedipine and glimepiride, and gene expression was analyzed. RESULTS Both WT and Kir6.2KO mice fed ST showed hyperinsulinemia and body weight gain. BCM, the number of islets and the expression levels of cyclinD2 messenger ribonucleic acid were increased in WT mice fed ST compared with those in WT mice fed normal chow. In contrast, no significant difference in BCM, the number of islets or the expression levels of cyclinD2 messenger ribonucleic acid were observed between Kir6.2KO mice fed normal chow and those fed ST. Incubation of MIN6-K8 β-cells in high-glucose media or with glimepiride increased cyclinD2 expression, whereas nifedipine attenuated a high-glucose-induced increase in cyclinD2 expression. CONCLUSIONS These results show that a high-starch diet increases BCM in an adenosine triphosphate-sensitive potassium channel-dependent manner, which is mediated through upregulation of cyclinD2 expression.
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Affiliation(s)
- Masatoshi Murase
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
| | - Yusuke Seino
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
| | - Ryuya Maekawa
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
| | - Atsushi Iida
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
| | - Kaori Hosokawa
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
| | - Tomohide Hayami
- Division of Molecular and Metabolic MedicineKobe University Graduate School of MedicineKobeJapan
- Yutaka Seino Distinguished Center for Diabetes ResearchKansai Electric Power Medical Research InstituteKobeJapan
- Division of DiabetesDepartment of Internal MedicineAichi Medical University School of MedicineNagakuteJapan
| | - Shin Tsunekawa
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
| | - Yoji Hamada
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
| | - Norihide Yokoi
- Division of Molecular and Metabolic MedicineKobe University Graduate School of MedicineKobeJapan
| | - Susumu Seino
- Division of Molecular and Metabolic MedicineKobe University Graduate School of MedicineKobeJapan
| | - Yoshitaka Hayashi
- Division of Stress Adaptation and ProtectionDepartment of Genetics ResearchInstitute of Environmental MedicineNagoya UniversityNagoyaJapan
| | - Hiroshi Arima
- Departments of Endocrinology and DiabetesNagoya University Graduate School of MedicineNagoyaJapan
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14
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Rachdaoui N, Polo-Parada L, Ismail-Beigi F. Prolonged Exposure to Insulin Inactivates Akt and Erk 1/2 and Increases Pancreatic Islet and INS1E β-Cell Apoptosis. J Endocr Soc 2018; 3:69-90. [PMID: 30697602 PMCID: PMC6344346 DOI: 10.1210/js.2018-00140] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/29/2018] [Indexed: 12/18/2022] Open
Abstract
Chronic hyperinsulinemia, in vivo, increases the resistance of peripheral tissues to insulin by desensitizing insulin signaling. Insulin, in a heterologous manner, can also cause IGF-1 resistance. The aim of the current study was to investigate whether insulin-mediated insulin and IGF-1 resistance develops in pancreatic β-cells and whether this resistance results in β-cell decompensation. Chronic exposure of rat islets or INS1E β-cells to increasing concentrations of insulin decreased AktS473 phosphorylation in response to subsequent acute stimulation with 10 nM insulin or IGF-1. Prolonged exposure to high insulin levels not only inhibited AktS473 phosphorylation, but it also resulted in a significant inhibition of the phosphorylation of P70S6 kinase and Erk1/2 phosphorylation in response to the acute stimulation by glucose, insulin, or IGF-1. Decreased activation of Akt, P70S6K, and Erk1/2 was associated with decreased insulin receptor substrate 2 tyrosine phosphorylation and insulin receptor β-subunit abundance; neither IGF receptor β-subunit content nor its phosphorylation were affected. These signaling impairments were associated with decreased SERCA2 expression, perturbed plasma membrane calcium current and intracellular calcium handling, increased endoplasmic reticulum stress markers such as eIF2αS51 phosphorylation and Bip (GRP78) expression, and increased islet and β-cell apoptosis. We demonstrate that prolonged exposure to high insulin levels induces not only insulin resistance, but in a heterologous manner causes resistance to IGF-1 in rat islets and insulinoma cells resulting in decreased cell survival. These findings suggest the possibility that chronic exposure to hyperinsulinemia may negatively affect β-cell mass by increasing β-cell apoptosis.
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Affiliation(s)
- Nadia Rachdaoui
- Division of Clinical and Molecular Endocrinology, Department of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Luis Polo-Parada
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, Missouri
| | - Faramarz Ismail-Beigi
- Division of Clinical and Molecular Endocrinology, Department of Medicine, Case Western Reserve University, Cleveland, Ohio
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15
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Abstract
SIGNIFICANCE Among many endogenous mediators, the gasotransmitter hydrogen sulfide (H2S) plays an important role in the regulation of glucose homeostasis. In this article we discuss different functional roles of H2S in several metabolic organs/tissues required in the maintenance of glucose homeostasis. Recent Advances: New evidence has emerged revealing the insulin sensitizing role of H2S in adipose tissue and skeletal muscle biology. In addition, H2S was demonstrated to be a potent stimulator of gluconeogenesis via the induction and stimulation of various glucose-producing pathways in the liver. CRITICAL ISSUES Similar to its other physiological effects, H2S exhibits paradoxical characteristics in the regulation of glucose homeostasis: (1) H2S stimulates glucose production via activation of gluconeogenesis and glycogenolysis in hepatocytes, yet inhibits lipolysis in adipocytes; (2) H2S stimulates glucose uptake into adipocytes and skeletal muscle but inhibits glucose uptake into hepatocytes; (3) H2S inhibits insulin secretion from pancreatic β cells, yet sensitizes insulin signaling and insulin-triggered response in adipose tissues and skeletal muscle. It is also unclear the impact H2S may have on glucose metabolism and utilization by other vital organs, such as the brain. FUTURE DIRECTIONS Recent reports and ongoing studies lay the foundation for a general, although highly incomplete, understanding of the effect of H2S on regulating glucose homeostasis. In this review, we describe the molecular mechanisms and physiological outcomes of the gasotransmitter H2S on organs and tissues required for homeostatic maintenance of blood glucose. Future directions highlighting the H2S-mediated homeostatic control of glucose metabolism under physiological and insulin-resistant conditions are also discussed. Antioxid. Redox Signal. 28, 1463-1482.
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Affiliation(s)
- Ashley Untereiner
- 1 Department of Anesthesiology, University of Texas Medical Branch , Galveston, Texas
| | - Lingyun Wu
- 2 Cardiovascular & Metabolic Research Unit and School of Human Kinetics, Laurentian University , Sudbury, Canada .,3 Health Sciences North Research Institute , Sudbury, Canada
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16
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He Y, Bai J, Liu P, Dong J, Tang Y, Zhou J, Han P, Xing J, Chen Y, Yu X. miR-494 protects pancreatic β-cell function by targeting PTEN in gestational diabetes mellitus. EXCLI JOURNAL 2017; 16:1297-1307. [PMID: 29333131 PMCID: PMC5763094 DOI: 10.17179/excli2017-491] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 11/18/2017] [Indexed: 12/13/2022]
Abstract
Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications characterized by insulin resistance and pancreatic β-cell dysfunction. Increasing evidence suggests that microRNAs (miRNAs) play key roles in the diverse types of diabetes, including GDM. However, the underlying mechanisms remain largely unknown. The purpose of this study is to investigate the role of microRNAs in GDM. The microarray data of dysregulated miRNAs in blood and placenta was retrieved in the GEO dataset under the accession number GSE19649. Quantitative reverse transcription PCR (qRT-PCR) was performed to analyze the expression levels of miR-494 in peripheral blood from twenty pairs of gestational diabetes (GDM) women and healthy women. Then, we investigated the effects of miR-494 on the insulin secretion of pancreatic β-cells. Moreover, the role of this miR-494 in regulating the proliferation and apoptosis of pancreatic β-cells were determined by MTT assay and flow cytometry, respectively in INS1 cells transfected with a miR-494 mimic or inhibitor. In addition, the direct target of miR-494 was confirmed using 3' untranslated region (UTR) luciferase reporter assay. Our data demonstrated that the miR-494 level was significantly decreased in the blood of GDM patients, and the low level was associated with a high concentration of blood glucose. Furthermore, overexpression of miR-494 improved pancreatic β-cell dysfunction by enhancing insulin secretion and total insulin content, inducing cell proliferation, and inhibiting cell apoptosis, whereas miR-494 knockdown exhibited decreased insulin secretion and proliferation, as well as stimulated apoptosis. In addition, phosphatase and tensin homolog (PTEN) which has been shown to play a pivotal role in apoptosis, was proved to be a direct target of miR-494 in pancreatic β-cells. More importantly, siRNA-induced downregulation of PTEN reversed the effects of miR-494 knockdown on insulin secretion, cell proliferation, and apoptosis of pancreatic β-cells.
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Affiliation(s)
- Yanfang He
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Jie Bai
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Ping Liu
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Jianxin Dong
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Yajuan Tang
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Jianli Zhou
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Ping Han
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Jun Xing
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Yan Chen
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
| | - Xiangyang Yu
- Department of Obstetrics and Gynecology; Affiliated Hospital of North China University of Science and Technology, Tangshan 063000, China
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17
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Anitha M, Reichardt F, Tabatabavakili S, Nezami BG, Chassaing B, Mwangi S, Vijay-Kumar M, Gewirtz A, Srinivasan S. Intestinal dysbiosis contributes to the delayed gastrointestinal transit in high-fat diet fed mice. Cell Mol Gastroenterol Hepatol 2016; 2:328-339. [PMID: 27446985 PMCID: PMC4945127 DOI: 10.1016/j.jcmgh.2015.12.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND & AIMS High-fat diet (HFD) feeding is associated with gastrointestinal motility disorders. We recently reported delayed colonic motility in mice fed a HFD mice for 11 weeks. In this study, we investigated the contributing role of gut microbiota in HFD-induced gut dysmotility. METHODS Male C57BL/6 mice were fed a HFD (60% kcal fat) or a regular/control diet (RD) (18% kcal fat) for 13 weeks. Serum and fecal endotoxin levels were measured, and relative amounts of specific gut bacteria in the feces assessed by real time PCR. Intestinal transit was measured by fluorescent-labeled marker and bead expulsion test. Enteric neurons were assessed by immunostaining. Oligofructose (OFS) supplementation with RD or HFD for 5 weeks was also studied. In vitro studies were performed using primary enteric neurons and an enteric neuronal cell line. RESULTS HFD-fed mice had reduced numbers of enteric nitrergic neurons and exhibited delayed gastrointestinal transit compared to RD-fed mice. HFD-fed mice had higher fecal Firmicutes and Escherichia coli and lower Bacteroidetes compared to RD-fed mice. OFS supplementation protected against enteric nitrergic neurons loss in HFD-fed mice, and improved intestinal transit time. OFS supplementation resulted in a reductions in fecal Firmicutes and Escherichia coli and serum endotoxin levels. In vitro, palmitate activation of TLR4 induced enteric neuronal apoptosis in a p-JNK1 dependent pathway. This apoptosis was prevented by a JNK inhibitor and in neurons from TLR4-/- mice. CONCLUSIONS Together our data suggest that intestinal dysbiosis in HFD fed mice contribute to the delayed intestinal motility by inducing a TLR4-dependant neuronal loss. Manipulation of gut microbiota with OFS improved intestinal motility in HFD mice.
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Affiliation(s)
- Mallappa Anitha
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania
| | - François Reichardt
- Department of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia
| | - Sahar Tabatabavakili
- Department of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia
| | - Behtash Ghazi Nezami
- Department of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia
| | - Benoit Chassaing
- Center for Inflammation, Immunity and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia
| | - Simon Mwangi
- Department of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia
| | - Matam Vijay-Kumar
- Department of Nutritional Sciences & Medicine, The Pennsylvania State University, University Park, Pennsylvania
| | - Andrew Gewirtz
- Center for Inflammation, Immunity and Infection, Institute for Biomedical Sciences, Georgia State University, Atlanta, Georgia
| | - Shanthi Srinivasan
- Department of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia,Correspondence Address correspondence to: Shanthi Srinivasan, MD, Division of Digestive Diseases, Whitehead Biomedical Research Building, 615 Michael Street, Suite 201A, Atlanta, Georgia 30322. fax: (404) 727-5767.Division of Digestive DiseasesWhitehead Biomedical Research Building615 Michael StreetSuite 201AAtlantaGeorgia 30322
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18
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Speckmann T, Sabatini PV, Nian C, Smith RG, Lynn FC. Npas4 Transcription Factor Expression Is Regulated by Calcium Signaling Pathways and Prevents Tacrolimus-induced Cytotoxicity in Pancreatic Beta Cells. J Biol Chem 2015; 291:2682-95. [PMID: 26663079 DOI: 10.1074/jbc.m115.704098] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Indexed: 12/16/2022] Open
Abstract
Cytosolic calcium influx activates signaling pathways known to support pancreatic beta cell function and survival by modulating gene expression. Impaired calcium signaling leads to decreased beta cell mass and diabetes. To appreciate the causes of these cytotoxic perturbations, a more detailed understanding of the relevant signaling pathways and their respective gene targets is required. In this study, we examined the calcium-induced expression of the cytoprotective beta cell transcription factor Npas4. Pharmacological inhibition implicated the calcineurin, Akt/protein kinase B, and Ca(2+)/calmodulin-dependent protein kinase signaling pathways in the regulation of Npas4 transcription and translation. Both Npas4 mRNA and protein had high turnover rates, and, at the protein level, degradation was mediated via the ubiquitin-proteasome pathway. Finally, beta cell cytotoxicity of the calcineurin inhibitor and immunosuppressant tacrolimus (FK-506) was prevented by Npas4 overexpression. These results delineate the pathways regulating Npas4 expression and stability and demonstrate its importance in clinical settings such as islet transplantation.
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Affiliation(s)
- Thilo Speckmann
- From the Diabetes Research Program, Child and Family Research Institute, Vancouver, British Columbia V5Z 4H4, Canada and the Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada
| | - Paul V Sabatini
- From the Diabetes Research Program, Child and Family Research Institute, Vancouver, British Columbia V5Z 4H4, Canada and the Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada
| | - Cuilan Nian
- From the Diabetes Research Program, Child and Family Research Institute, Vancouver, British Columbia V5Z 4H4, Canada and the Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada
| | - Riley G Smith
- From the Diabetes Research Program, Child and Family Research Institute, Vancouver, British Columbia V5Z 4H4, Canada and
| | - Francis C Lynn
- From the Diabetes Research Program, Child and Family Research Institute, Vancouver, British Columbia V5Z 4H4, Canada and the Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V5Z 1M9, Canada
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19
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Israely E, Ginsberg M, Nolan D, Ding BS, James D, Elemento O, Rafii S, Rabbany SY. Akt suppression of TGFβ signaling contributes to the maintenance of vascular identity in embryonic stem cell-derived endothelial cells. Stem Cells 2014; 32:177-90. [PMID: 23963623 DOI: 10.1002/stem.1521] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 07/23/2013] [Accepted: 07/24/2013] [Indexed: 01/04/2023]
Abstract
The ability to generate and maintain stable in vitro cultures of mouse endothelial cells (ECs) has great potential for genetic dissection of the numerous pathologies involving vascular dysfunction as well as therapeutic applications. However, previous efforts at achieving sustained cultures of primary stable murine vascular cells have fallen short, and the cellular requirements for EC maintenance in vitro remain undefined. In this study, we have generated vascular ECs from mouse embryonic stem (ES) cells and show that active Akt is essential to their survival and propagation as homogeneous monolayers in vitro. These cells harbor the phenotypical, biochemical, and functional characteristics of ECs and expand throughout long-term cultures, while maintaining their angiogenic capacity. Moreover, Akt-transduced embryonic ECs form functional perfused vessels in vivo that anastomose with host blood vessels. We provide evidence for a novel function of Akt in stabilizing EC identity, whereby the activated form of the protein protects mouse ES cell-derived ECs from TGFβ-mediated transdifferentiation by downregulating SMAD3. These findings identify a role for Akt in regulating the developmental potential of ES cell-derived ECs and demonstrate that active Akt maintains endothelial identity in embryonic ECs by interfering with active TGFβ-mediated processes that would ordinarily usher these cells to alternate fates.
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Affiliation(s)
- Edo Israely
- Department of Genetic Medicine, Ansary Stem Cell Institute, Howard Hughes Medical Institute, Weill Cornell Medical College, New York, New York, USA
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20
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Shrestha N, Araújo F, Sarmento B, Hirvonen J, Santos HA. Gene-based therapy for Type 1 diabetes mellitus: viral and nonviral vectors. ACTA ACUST UNITED AC 2014. [DOI: 10.2217/dmt.14.31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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22
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PTBP1 is required for glucose-stimulated cap-independent translation of insulin granule proteins and Coxsackieviruses in beta cells. Mol Metab 2014; 3:518-30. [PMID: 25061557 PMCID: PMC4099505 DOI: 10.1016/j.molmet.2014.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/02/2014] [Accepted: 05/06/2014] [Indexed: 12/15/2022] Open
Abstract
Glucose and GLP-1 stimulate not only insulin secretion, but also the post-transcriptional induction of insulin granule biogenesis. This process involves the nucleocytoplasmic translocation of the RNA binding protein PTBP1. Binding of PTBP1 to the 3'-UTRs of mRNAs for insulin and other cargoes of beta cell granules increases their stability. Here we show that glucose enhances also the binding of PTBP1 to the 5'-UTRs of these transcripts, which display IRES activity, and their translation exclusively in a cap-independent fashion. Accordingly, glucose-induced biosynthesis of granule cargoes was unaffected by pharmacological, genetic or Coxsackievirus-mediated inhibition of cap-dependent translation. Infection with Coxsackieviruses, which also depend on PTBP1 for their own cap-independent translation, reduced instead granule stores and insulin release. These findings provide insight into the mechanism for glucose-induction of insulin granule production and on how Coxsackieviruses, which have been implicated in the pathogenesis of type 1 diabetes, can foster beta cell failure.
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Key Words
- Beta cells
- CV, Coxsackievirus
- Diabetes
- ER, endoplasmic reticulum
- EV, Enterovirus
- F, Faulkner
- FL, firefly luciferase
- IRES, internal ribosomal entry site
- ITAF, IRES-trans-acting factor
- Insulin
- MCA, MIN6 cell adapted
- PABP, poly(A)-binding protein
- PC, prohormone convertase
- PTBP1, polypyrimidine tract-binding protein 1
- Polypyrimidine tract-binding protein
- S6K1, p70S6 Kinase 1
- Secretory granules
- T1D, type 1 diabetes
- Translation
- UTR, untranslated region
- Virus
- eIF4E-V5, eIF4E tagged at its C-terminus with a V5-epitope
- mTORC1, mammalian Target Of Rapamycin Complex 1
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23
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Zheng YL, Li C, Hu YF, Cao L, Wang H, Li B, Lu XH, Bao L, Luo HY, Shukla V, Amin ND, Pant HC. Cdk5 inhibitory peptide (CIP) inhibits Cdk5/p25 activity induced by high glucose in pancreatic beta cells and recovers insulin secretion from p25 damage. PLoS One 2013; 8:e63332. [PMID: 24039692 PMCID: PMC3764143 DOI: 10.1371/journal.pone.0063332] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 04/02/2013] [Indexed: 11/27/2022] Open
Abstract
Cdk5/p25 hyperactivity has been demonstrated to lead to neuron apoptosis and degenerations. Chronic exposure to high glucose (HG) results in hyperactivity of Cdk5 and reduced insulin secretion. Here, we set out to determine whether abnormal upregulation of Cdk5/p25 activity may be induced in a pancreatic beta cell line, Min6 cells. We first confirmed that p25 were induced in overexpressed p35 cells treated with HG and increased time course dependence. Next, we showed that no p25 was detected under short time HG stimulation (4–12 hrs), however was detectable in the long exposure in HG cells (24 hrs and 48 hrs). Cdk5 activity in the above cells was much higher than low glucose treated cells and resulted in more than 50% inhibition of insulin secretion. We confirmed these results by overexpression of p25 in Min6 cells. As in cortical neurons, CIP, a small peptide, inhibited Cdk5/p25 activity and restored insulin secretion. The same results were detected in co-infection of dominant negative Cdk5 (DNCdk5) with p25. CIP also reduced beta cells apoptosis induced by Cdk5/p25. These studies indicate that Cdk5/p25 hyperactivation deregulates insulin secretion and induces cell death in pancreatic beta cells and suggests that CIP may serve as a therapeutic agent for type 2 diabetes.
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Affiliation(s)
- Ya-Li Zheng
- Department of Nephrology, Ningxia People's Hospital, Yinchuan, Ningxia Province, China
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24
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Sabatini PV, Krentz NA, Zarrouki B, Westwell-Roper CY, Nian C, Uy RA, Shapiro AJ, Poitout V, Lynn FC. Npas4 is a novel activity-regulated cytoprotective factor in pancreatic β-cells. Diabetes 2013; 62:2808-20. [PMID: 23656887 PMCID: PMC3717850 DOI: 10.2337/db12-1527] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cellular homeostasis requires intrinsic sensing mechanisms to temper function in the face of prolonged activity. In the pancreatic β-cell, glucose is likely a physiological trigger that activates an adaptive response to stimulation, thereby maintaining cellular homeostasis. Immediate early genes (IEGs) are activated as a first line of defense in cellular homeostasis and are largely responsible for transmitting an environmental cue to a cellular response. Here we examine the regulation and function of the novel β-cell IEG, neuronal PAS domain protein 4 (Npas4). Using MIN6 cells, mouse and human islets, as well as in vivo infusions, we demonstrate that Npas4 is expressed within pancreatic islets and is upregulated by β-cell depolarizing agents. Npas4 tempers β-cell function through a direct inhibitory interaction with the insulin promoter and by blocking the potentiating effects of GLP-1 without significantly reducing glucose-stimulated secretion. Finally, Npas4 expression is induced by classical endoplasmic reticulum (ER) stressors and can prevent thapsigargin- and palmitate-induced dysfunction and cell death. These results suggest that Npas4 is a key activity-dependent regulator that improves β-cell efficiency in the face of stress. We posit that Npas4 could be a novel therapeutic target in type 2 diabetes that could both reduce ER stress and cell death and maintain basal cell function.
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Affiliation(s)
- Paul V. Sabatini
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nicole A.J. Krentz
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Bader Zarrouki
- Montreal Diabetes Research Center, CRCHUM, and Department of Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Clara Y. Westwell-Roper
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Cuilan Nian
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ryan A. Uy
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
| | | | - Vincent Poitout
- Montreal Diabetes Research Center, CRCHUM, and Department of Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Francis C. Lynn
- Diabetes Research Group, Child and Family Research Institute, Vancouver, British Columbia, Canada
- Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding author: Francis C. Lynn,
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25
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Puddu A, Sanguineti R, Mach F, Dallegri F, Viviani GL, Montecucco F. Update on the protective molecular pathways improving pancreatic beta-cell dysfunction. Mediators Inflamm 2013; 2013:750540. [PMID: 23737653 PMCID: PMC3659509 DOI: 10.1155/2013/750540] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/10/2013] [Indexed: 12/16/2022] Open
Abstract
The primary function of pancreatic beta-cells is to produce and release insulin in response to increment in extracellular glucose concentrations, thus maintaining glucose homeostasis. Deficient beta-cell function can have profound metabolic consequences, leading to the development of hyperglycemia and, ultimately, diabetes mellitus. Therefore, strategies targeting the maintenance of the normal function and protecting pancreatic beta-cells from injury or death might be crucial in the treatment of diabetes. This narrative review will update evidence from the recently identified molecular regulators preserving beta-cell mass and function recovery in order to suggest potential therapeutic targets against diabetes. This review will also highlight the relevance for novel molecular pathways potentially improving beta-cell dysfunction.
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Affiliation(s)
- Alessandra Puddu
- Department of Internal Medicine, University of Genoa, Viale Benedetto XV 6, 16132 Genova, Italy
| | - Roberta Sanguineti
- Department of Internal Medicine, University of Genoa, Viale Benedetto XV 6, 16132 Genova, Italy
| | - François Mach
- Division of Cardiology, Geneva University Hospitals, Faculty of Medicine, Foundation for Medical Researches, Avenue de la Roseraie 64, 1211 Geneva 4, Switzerland
| | - Franco Dallegri
- First Medical Clinic, Laboratory of Phagocyte Physiopathology and Inflammation, Department of Internal Medicine, University of Genoa, Viale Benedetto XV 6, 16132 Genova, Italy
| | - Giorgio Luciano Viviani
- Department of Internal Medicine, University of Genoa, Viale Benedetto XV 6, 16132 Genova, Italy
| | - Fabrizio Montecucco
- Division of Cardiology, Geneva University Hospitals, Faculty of Medicine, Foundation for Medical Researches, Avenue de la Roseraie 64, 1211 Geneva 4, Switzerland
- First Medical Clinic, Laboratory of Phagocyte Physiopathology and Inflammation, Department of Internal Medicine, University of Genoa, Viale Benedetto XV 6, 16132 Genova, Italy
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26
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Lee H, Park HS, Hong SH, Choi OK, Cho SD, Park J, Oh JE, Chung SS, Jung HS, Park KS. 4-Deoxypyridoxine improves the viability of isolated pancreatic islets ex vivo. Islets 2013; 5:116-21. [PMID: 23756681 DOI: 10.4161/isl.25254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The successful islet transplantation, for the treatment of type 1 diabetes, depends on the quantity and the quality of transplanted islets. Previously, it has reported that the significant loss of isolated islet mass could be prevented by sphingolipid metabolite, sphinogosine 1-phophate (S1P). This study was performed to elucidate whether the beneficial effects of S1P maintaining isolated pancreatic islets ex vivo are mimicked by modulation of intracellular S1P. We tested the in vitro effect of various agents that modulate intracellular S1P levels in insulinoma cell lines and isolated islets to compare their anti-apoptotic effects with that of S1P. As results, we discovered that 4-deoxypyridoxine (DOP), which inhibits the degradation of intracellular S1P by inhibiting S1P lyase (SPL) activity, minimized the chemically induced apoptosis of insulinoma cell lines as S1P did. Also, supplementation of DOP in the culture media protected the regression of isolated islets that have been maintained ex vivo at least for 18 h providing the evidence of increasing viability of isolated islets with DOP, which impaired SPL activity. In conclusion, these results suggest that the application of SPL inhibitors could be considered as a supplement for the maintenance of viable islets isolated from donor sources in the process of islet transplantation.
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Affiliation(s)
- Hakmo Lee
- Department of Internal Medicine; Seoul National University College of Medicine; Seoul, Republic of Korea; Innovative Research Institute for Cell Therapy; Seoul National University Hospital; Seoul, Republic of Korea; Biomedical Research Institute; Seoul National University Hospital; Seoul, Republic of Korea
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27
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Kim JH, Park YK, Kim JE, Lee SP, Kim BC, Jang BC. Crude extract of Ceriporia lacerata has a protective effect on dexamethasone-induced cytotoxicity in INS-1 cells via the modulation of PI3K/PKB activity. Int J Mol Med 2013; 32:179-86. [PMID: 23624822 DOI: 10.3892/ijmm.2013.1364] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 12/14/2012] [Indexed: 11/05/2022] Open
Abstract
Excessive and/or long-term glucocorticoid therapy reduces β-cell mass and induces hyperglycemia, which contribute to the development of steroid‑induced diabetes. Ceriporia (C.) lacerata is one of the white‑rot fungi and has been used in bioremediations, such as lignocellulose degradation, in nature. The pharmacologic effect of C. lacerata on steroid-induced β-cell toxicity is not known. In this study, we evaluated the effect of a crude extract from a submerged cultivation of C. lacerata on the survival and apoptosis of INS-1 rat insulin-secreting cells exposed to dexamethasone (Dex), a synthetic diabetogenic glucocorticoid. Treatment with the C. lacerata crude extract (CLCE) largely blocked the Dex-induced reduction in survival and apoptosis of INS-1 cells. Moreover, CLCE treatment inhibited Dex-induced protein kinase B (PKB) dephosphorylation without affecting Dex-induced extracellular signal-regulated protein kinase-1/2 dephosphorylation and MKP-1 upregulation. Importantly, the protective effect of CLCE on Dex-induced cytotoxicity in INS-1 cells was attenuated by LY294002, an inhibitor of PI3K/PKB. CLCE treatment, however, did not protect the INS-1 cells from the cytotoxic effects triggered by other insults, such as interleukin-1β (an inflammatory cytokine), streptozotocin (a diabetogenic drug), thapsigargin (a calcium mobilizing agent), and tunicamycin (an ER stress inducer). Collectively, these findings demonstrate for the first time the ability of CLCE to specifically protect INS-1 cells from Dex-induced cytotoxicity through the modulation of the PI3K/PKB pathway. It is suggested that CLCE may be applied for the prevention and/or treatment of steroid diabetes in which reduction of β-cell survival and induction of β-cell apoptosis play pathogenic roles.
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Affiliation(s)
- Ji-Hye Kim
- Department of Medical Genetic Engineering, Keimyung University School of Medicine, Dalseo-gu, Daegu 704-701, Republic of Korea
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28
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Sathanoori R, Olde B, Erlinge D, Göransson O, Wierup N. Cocaine- and amphetamine-regulated transcript (CART) protects beta cells against glucotoxicity and increases cell proliferation. J Biol Chem 2012; 288:3208-18. [PMID: 23250745 DOI: 10.1074/jbc.m112.437145] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cocaine- and amphetamine-regulated transcript (CART) is an islet peptide that promotes glucose-stimulated insulin secretion in beta cells via cAMP/PKA-dependent pathways. In addition, CART is a regulator of neuronal survival. In this study, we examined the effect of exogenous CART 55-102 on beta cell viability and dissected its signaling mechanisms. Evaluation of DNA fragmentation and chromatin condensation revealed that CART 55-102 reduced glucotoxicity-induced apoptosis in both INS-1 (832/13) cells and isolated rat islets. Glucotoxicity in INS-1 (832/13) cells also caused a 50% reduction of endogenous CART protein. We show that CART increased proliferation in INS-1 (832/13) cells, an effect that was blocked by PKA, PKB, and MEK1 inhibitors. In addition, CART induced phosphorylation of CREB, IRS, PKB, FoxO1, p44/42 MAPK, and p90RSK in INS-1 (832/13) cells and isolated rat islets, all key mediators of cell survival and proliferation. Thus, we demonstrate that CART 55-102 protects beta cells against glucotoxicity and promotes proliferation. Taken together our data point to the potential use of CART in therapeutic interventions targeted at enhancing functional beta cell mass and long-term insulin secretion in T2D.
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29
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Bensellam M, Laybutt DR, Jonas JC. The molecular mechanisms of pancreatic β-cell glucotoxicity: recent findings and future research directions. Mol Cell Endocrinol 2012; 364:1-27. [PMID: 22885162 DOI: 10.1016/j.mce.2012.08.003] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/11/2012] [Accepted: 08/01/2012] [Indexed: 02/06/2023]
Abstract
It is well established that regular physiological stimulation by glucose plays a crucial role in the maintenance of the β-cell differentiated phenotype. In contrast, prolonged or repeated exposure to elevated glucose concentrations both in vitro and in vivo exerts deleterious or toxic effects on the β-cell phenotype, a concept termed as glucotoxicity. Evidence indicates that the latter may greatly contribute to the pathogenesis of type 2 diabetes. Through the activation of several mechanisms and signaling pathways, high glucose levels exert deleterious effects on β-cell function and survival and thereby, lead to the worsening of the disease over time. While the role of high glucose-induced β-cell overstimulation, oxidative stress, excessive Unfolded Protein Response (UPR) activation, and loss of differentiation in the alteration of the β-cell phenotype is well ascertained, at least in vitro and in animal models of type 2 diabetes, the role of other mechanisms such as inflammation, O-GlcNacylation, PKC activation, and amyloidogenesis requires further confirmation. On the other hand, protein glycation is an emerging mechanism that may play an important role in the glucotoxic deterioration of the β-cell phenotype. Finally, our recent evidence suggests that hypoxia may also be a new mechanism of β-cell glucotoxicity. Deciphering these molecular mechanisms of β-cell glucotoxicity is a mandatory first step toward the development of therapeutic strategies to protect β-cells and improve the functional β-cell mass in type 2 diabetes.
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Affiliation(s)
- Mohammed Bensellam
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium
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30
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Bone RN, Icyuz M, Zhang Y, Zhang Y, Cui W, Wang H, Peng JB, Matthews QL, Siegal GP, Wu H. Gene transfer of active Akt1 by an infectivity-enhanced adenovirus impacts β-cell survival and proliferation differentially in vitro and in vivo. Islets 2012; 4. [PMID: 23183538 PMCID: PMC3605165 DOI: 10.4161/isl.22721] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Type 1 Diabetes is characterized by an absolute insulin deficiency due to the autoimmune destruction of insulin producing β-cells in the pancreatic islets. Akt1/Protein Kinase B is the direct downstream target of PI3 Kinase activation, and has shown potent anti-apoptotic and proliferation-inducing activities. This study was designed to explore whether gene transfer of constitutively active Akt1 (CA-Akt1) would promote β-cell survival and proliferation, thus be protective against experimental diabetes. In the study, a fiber-modified infectivity-enhanced adenoviral vector, Ad5RGDpK7, was used to deliver rat insulin promoter (RIP)-driven CA-Akt1 into β-cells. Our data showed this vector efficiently delivered CA-Akt1 into freshly isolated pancreatic islets, and promoted islet cell survival and β-cell proliferation in vitro. The therapeutic effect of the vector in vivo was assessed using streptozotocin (STZ)-induced diabetes mice. Two means of vector administration were explored: intravenous and intra-bile ductal injections. While direct vector administration into pancreas via bile-ductal injection resulted in local adverse effect, intravenous injection of the vectors offered therapeutic benefits. Further analysis suggests systemic vector administration caused endogenous Akt expression and activation in islets, which may be responsible, at least in part, for the protective effect of the infectivity-enhanced CA-Akt1 gene delivery vector. Taken together, our data suggest CA-Akt1 is effective in promoting β-cell survival and proliferation in vitro, but direct in vivo use is compromised by the efficacy of transgene delivery into β-cells. Nonetheless, the vector evoked the expression and activation of endogenous Akt in the islets, thus offering beneficial bystander effect against STZ-induced diabetes.
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Affiliation(s)
- Robert N. Bone
- Department of Pathology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Mert Icyuz
- Department of Medicine; University of Alabama at Birmingham; Birmingham, AL USA
| | - Yanqing Zhang
- Department of Medicine; Section of Endocrinology; Tulane University; New Orleans, LA USA
| | - Yuan Zhang
- Department of Medicine; University of Alabama at Birmingham; Birmingham, AL USA
| | - Wanxing Cui
- Department of Surgery; University of Alabama at Birmingham; Birmingham, AL USA
| | - Hongjun Wang
- Department of Surgery; Medical University of South Carolina; Charleston, SC USA
| | - Ji-Bin Peng
- Department of Medicine; University of Alabama at Birmingham; Birmingham, AL USA
| | - Qiana L. Matthews
- Department of Medicine; University of Alabama at Birmingham; Birmingham, AL USA
| | - Gene P. Siegal
- Department of Pathology; University of Alabama at Birmingham; Birmingham, AL USA
| | - Hongju Wu
- Department of Medicine; Section of Endocrinology; Tulane University; New Orleans, LA USA
- Correspondence to: Hongju Wu,
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31
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Joshi MS, Wattanapitayakul S, Schanbacher BL, Bauer JA. Effects of human endothelial gene polymorphisms on cellular responses to hyperglycaemia: role of NOS3 (Glu298Asp) and ACE (I/D) polymorphisms. Diab Vasc Dis Res 2011; 8:276-83. [PMID: 21844127 DOI: 10.1177/1479164111416679] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The functional relevance of NOS3 and ACE genetic variations to endothelial cell function is largely unstudied. Here we tested the functional relevance of the NOS3 (Glu298Asp) polymorphism and ACE (I/D) polymorphism in endothelial cells in vitro. Our hypothesis was that these genetic polymorphisms alter endothelial cell sensitivity to glucose and 3-nitrotyrosine (3NT). Genotyped HUVECs were incubated with glucose, free 3NT or a combination of these two toxicants. Significant differences in glucose-induced cell death and free 3NT-induced cell death were observed among the NOS3 genotypes. Combined glucose/3NT caused increased toxicity among the NOS3 genotypes. No differences were observed among the ACE genotypes in their responses to glucose/3NT. These data demonstrate that the NOS3 genotype may be an important predictor of, or be mechanistically involved in, endothelial vulnerability, whereas the ACE I/D genotype is apparently less important. Thus this NOS3 genetic variation may play a role in vulnerability to endothelium-dependent diabetic vascular complications.
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Affiliation(s)
- Mandar S Joshi
- The Ritchie Centre, Monash Institute of Medical Research, Clayton VIC, Australia.
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32
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Zhang L, Yang G, Tang G, Wu L, Wang R. Rat pancreatic level of cystathionine γ-lyase is regulated by glucose level via specificity protein 1 (SP1) phosphorylation. Diabetologia 2011; 54:2615-25. [PMID: 21618058 DOI: 10.1007/s00125-011-2187-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 04/19/2011] [Indexed: 01/24/2023]
Abstract
AIMS/HYPOTHESIS Cystathionine γ-lyase (CSE) catalyses the endogenous production of hydrogen sulphide (H(2)S) in pancreatic beta cells, and H(2)S has been shown to inhibit insulin release from these cells. As altered pancreatic H(2)S production modulated by glucose has been previously shown, we hypothesised that the Cse gene could be regulated by glucose level in insulin-secreting cells. METHODS The effects of glucose on CSE protein level and mRNA level were analysed in INS-1E cells. Glucose effect on Cse promoter activity was tested by constructing a proximal Cse promoter vector including specificity protein 1 (Sp1) consensus sequence. RESULTS High glucose (20 mmol/l) inhibited H(2)S production in INS-1E cells and freshly isolated rat pancreatic islets. Cse mRNA expression, CSE activity and protein abundance were also profoundly reduced by high glucose. The involvement of SP1 in basal and high-glucose-regulated CSE production was demonstrated. Sp1-knockdown abolished a large portion of CSE production at basal glucose. Phosphorylation of SP1 stimulated by high glucose was inhibited by p38 mitogen-activated protein kinase (MAPK) inhibitors SB203580 and SB202190. After blocking p38 MAPK phosphorylation, the inhibitive effects of high glucose on CSE protein production and promoter activity in INS-1E cells were also virtually abolished. CONCLUSIONS/INTERPRETATION Glucose stimulates the phosphorylation of SP1 via p38 MAPK activation, which leads to decreased Cse promoter activity and subsequent downregulation of Cse gene expression. Inhibited H(2)S production through glucose-mediated CSE activity and production alterations may be involved in the fine control of glucose-induced insulin secretion.
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Affiliation(s)
- L Zhang
- Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, Canada, P7B 5E1
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Sharma G, Prossnitz ER. Mechanisms of estradiol-induced insulin secretion by the G protein-coupled estrogen receptor GPR30/GPER in pancreatic beta-cells. Endocrinology 2011; 152:3030-9. [PMID: 21673097 PMCID: PMC3138237 DOI: 10.1210/en.2011-0091] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Sexual dimorphism and supplementation studies suggest an important role for estrogens in the amelioration of glucose intolerance and diabetes. Because little is known regarding the signaling mechanisms involved in estradiol-mediated insulin secretion, we investigated the role of the G protein-coupled receptor 30, now designated G protein-coupled estrogen receptor (GPER), in activating signal transduction cascades in β-cells, leading to secretion of insulin. GPER function in estradiol-induced signaling in the pancreatic β-cell line MIN6 was assessed using small interfering RNA and GPER-selective ligands (G-1 and G15) and in islets isolated from wild-type and GPER knockout mice. GPER is expressed in MIN6 cells, where estradiol and the GPER-selective agonist G-1 mediate calcium mobilization and activation of ERK and phosphatidylinositol 3-kinase. Both estradiol and G-1 induced insulin secretion under low- and high-glucose conditions, which was inhibited by pretreatment with GPER antagonist G15 as well as depletion of GPER by small interfering RNA. Insulin secretion in response to estradiol and G-1 was dependent on epidermal growth factor receptor and ERK activation and further modulated by phosphatidylinositol 3-kinase activity. In islets isolated from wild-type mice, the GPER antagonist G15 inhibited insulin secretion induced by estradiol and G-1, both of which failed to induce insulin secretion in islets obtained from GPER knockout mice. Our results indicate that GPER activation of the epidermal growth factor receptor and ERK in response to estradiol treatment plays a critical role in the secretion of insulin from β-cells. The results of this study suggest that the activation of downstream signaling pathways by the GPER-selective ligand G-1 could represent a novel therapeutic strategy in the treatment of diabetes.
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Affiliation(s)
- Geetanjali Sharma
- Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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Tanabe K, Liu Y, Hasan SD, Martinez SC, Cras-Méneur C, Welling CM, Bernal-Mizrachi E, Tanizawa Y, Rhodes CJ, Zmuda E, Hai T, Abumrad NA, Permutt MA. Glucose and fatty acids synergize to promote B-cell apoptosis through activation of glycogen synthase kinase 3β independent of JNK activation. PLoS One 2011; 6:e18146. [PMID: 21541314 PMCID: PMC3082528 DOI: 10.1371/journal.pone.0018146] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 02/27/2011] [Indexed: 01/09/2023] Open
Abstract
Background The combination of elevated glucose and free-fatty acids (FFA), prevalent in diabetes, has been suggested to be a major contributor to pancreatic β-cell death. This study examines the synergistic effects of glucose and FFA on β-cell apoptosis and the molecular mechanisms involved. Mouse insulinoma cells and primary islets were treated with palmitate at increasing glucose and effects on apoptosis, endoplasmic reticulum (ER) stress and insulin receptor substrate (IRS) signaling were examined. Principal Findings Increasing glucose (5–25 mM) with palmitate (400 µM) had synergistic effects on apoptosis. Jun NH2-terminal kinase (JNK) activation peaked at the lowest glucose concentration, in contrast to a progressive reduction in IRS2 protein and impairment of insulin receptor substrate signaling. A synergistic effect was observed on activation of ER stress markers, along with recruitment of SREBP1 to the nucleus. These findings were confirmed in primary islets. The above effects associated with an increase in glycogen synthase kinase 3β (Gsk3β) activity and were reversed along with apoptosis by an adenovirus expressing a kinase dead Gsk3β. Conclusions/Significance Glucose in the presence of FFA results in synergistic effects on ER stress, impaired insulin receptor substrate signaling and Gsk3β activation. The data support the importance of controlling both hyperglycemia and hyperlipidemia in the management of Type 2 diabetes, and identify pancreatic islet β-cell Gsk3β as a potential therapeutic target.
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Affiliation(s)
- Katsuya Tanabe
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Yang Liu
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Syed D. Hasan
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sara C. Martinez
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Corentin Cras-Méneur
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Cris M. Welling
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Ernesto Bernal-Mizrachi
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Yukio Tanizawa
- Division of Endocrinology, Metabolism, Hematological Sciences and Therapeutics Department of Bio-Signal Analysis, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, Japan
| | - Christopher J. Rhodes
- Department of Medicine, Kovler Diabetes Center, University of Chicago, Chicago, Illinois, United States of America
| | - Erik Zmuda
- Department of Molecular and Cellular Biochemistry, Center for Molecular Neurobiology, Ohio State University, Columbus, Ohio, United States of America
| | - Tsonwin Hai
- Department of Molecular and Cellular Biochemistry, Center for Molecular Neurobiology, Ohio State University, Columbus, Ohio, United States of America
| | - Nada A. Abumrad
- Division of Nutritional Science, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - M. Alan Permutt
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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Wang X, Liu Y, Yang Z, Zhang Z, Zhou W, Ye Z, Zhang W, Zhang S, Yang Z, Feng X, Chen F, Hu R. Glucose metabolism-related protein 1 (GMRP1) regulates pancreatic beta cell proliferation and apoptosis via activation of Akt signalling pathway in rats and mice. Diabetologia 2011; 54:852-63. [PMID: 21267538 DOI: 10.1007/s00125-011-2048-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 12/10/2010] [Indexed: 12/31/2022]
Abstract
AIMS/HYPOTHESIS We attempted to elucidate the impacts on and possible mechanisms by which glucose metabolism-related protein 1 (GMRP1) affects beta cell survival. METHODS Adenovirus-mediated GMRP1 overproduction and siRNA-mediated knockdown were performed in INS-1E cells and rat islets, after which cell proliferation or apoptosis were determined, and phosphorylation of Akt and BCL2-associated agonist of cell death (BAD) investigated. INS-1E cells and rat islets were cultured at 5.6 (low) or 25 mmol/l (high) glucose for 24 or 48 h, and cell proliferation or apoptosis and GMRP1 levels were investigated. INS-1E cells were treated for 24 h with 0, 10, 50 and 100 nmol/l insulin, and GMRP1 levels were determined. After INS-1E cells were transfected with siRNA for 72 h, high glucose-induced cell proliferation and insulin-stimulated Akt phosphorylation were investigated. Glucose-infused rat models were established and beta cell proliferation and mass were evaluated. Levels of GMRP1, and phosphorylation of Akt and BAD were determined in glucose-infused islets. The GMRP1-mediated Akt pathway was also investigated in db/db mice. RESULTS Overproduction of GMRP1 promoted beta cell proliferation via increased phosphorylation of Akt. Knockdown of Gmrp1 (also known as Btbd10) reduced phosphorylation of Akt with enhanced beta cell apoptosis. High glucose increased GMRP1 levels and cell proliferation in INS-1E cells and islet cells. Knockdown of Gmrp1 decreased high glucose-induced cell proliferation and insulin-stimulated Akt phosphorylation. Increased GMRP1 levels were involved in the enhancement of beta cell proliferation and mass in glucose-infused islets. Decreased GMRP1 levels may participate in beta cell apoptosis of db/db mice. CONCLUSIONS/INTERPRETATION GMRP1 regulates pancreatic beta cell proliferation and apoptosis via activation of Akt signalling pathway.
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Affiliation(s)
- X Wang
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Wulumuqi Road Middle, Shanghai 200040, People's Republic of China.
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Soleimanpour SA, Crutchlow MF, Ferrari AM, Raum JC, Groff DN, Rankin MM, Liu C, De León DD, Naji A, Kushner JA, Stoffers DA. Calcineurin signaling regulates human islet {beta}-cell survival. J Biol Chem 2010; 285:40050-9. [PMID: 20943662 DOI: 10.1074/jbc.m110.154955] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The calcium-regulated phosphatase calcineurin intersects with both calcium and cAMP-mediated signaling pathways in the pancreatic β-cell. Pharmacologic calcineurin inhibition, necessary to prevent rejection in the setting of organ transplantation, is associated with post-transplant β-cell failure. We sought to determine the effect of calcineurin inhibition on β-cell replication and survival in rodents and in isolated human islets. Further, we assessed whether the GLP-1 receptor agonist and cAMP stimulus, exendin-4 (Ex-4), could rescue β-cell replication and survival following calcineurin inhibition. Following treatment with the calcineurin inhibitor tacrolimus, human β-cell apoptosis was significantly increased. Although we detected no human β-cell replication, tacrolimus significantly decreased rodent β-cell replication. Ex-4 nearly normalized both human β-cell survival and rodent β-cell replication when co-administered with tacrolimus. We found that tacrolimus decreased Akt phosphorylation, suggesting that calcineurin could regulate replication and survival via the PI3K/Akt pathway. We identify insulin receptor substrate-2 (Irs2), a known cAMP-responsive element-binding protein target and upstream regulator of the PI3K/Akt pathway, as a novel calcineurin target in β-cells. Irs2 mRNA and protein are decreased by calcineurin inhibition in both rodent and human islets. The effect of calcineurin on Irs2 expression is mediated at least in part through the nuclear factor of activated T-cells (NFAT), as NFAT occupied the Irs2 promoter in a calcineurin-sensitive manner. Ex-4 restored Irs2 expression in tacrolimus-treated rodent and human islets nearly to baseline. These findings reveal calcineurin as a regulator of human β-cell survival in part through regulation of Irs2, with implications for the pathogenesis and treatment of diabetes following organ transplantation.
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Affiliation(s)
- Scott A Soleimanpour
- Division of Endocrinology, Department of Medicine and the Institute for Diabetes, Obesity, and Metabolism, the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Bindom SM, Hans CP, Xia H, Boulares AH, Lazartigues E. Angiotensin I-converting enzyme type 2 (ACE2) gene therapy improves glycemic control in diabetic mice. Diabetes 2010; 59:2540-8. [PMID: 20660625 PMCID: PMC3279528 DOI: 10.2337/db09-0782] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Several clinical studies have shown the benefits of renin-angiotensin system (RAS) blockade in the development of diabetes, and a local RAS has been identified in pancreatic islets. Angiotensin I-converting enzyme (ACE)2, a new component of the RAS, has been identified in the pancreas, but its role in β-cell function remains unknown. Using 8- and 16-week-old obese db/db mice, we examined the ability of ACE2 to alter pancreatic β-cell function and thereby modulate hyperglycemia. RESEARCH DESIGN AND METHODS Both db/db and nondiabetic lean control (db/m) mice were infected with an adenovirus expressing human ACE2 (Ad-hACE2-eGFP) or the control virus (Ad-eGFP) via injection into the pancreas. Glycemia and β-cell function were assessed 1 week later at the peak of viral expression. RESULTS In 8-week-old db/db mice, Ad-hACE2-eGFP significantly improved fasting glycemia, enhanced intraperitoneal glucose tolerance, increased islet insulin content and β-cell proliferation, and reduced β-cell apoptosis compared with Ad-eGFP. ACE2 overexpression had no effect on insulin sensitivity in comparison with Ad-eGFP treatment in diabetic mice. Angiotensin-(1-7) receptor blockade by D-Ala(7)-Ang-(1-7) prevented the ACE2-mediated improvements in intraperitoneal glucose tolerance, glycemia, and islet function and also impaired insulin sensitivity in both Ad-hACE2-eGFP- and Ad-eGFP-treated db/db mice. D-Ala(7)-Ang-(1-7) had no effect on db/m mice. In 16-week-old diabetic mice, Ad-hACE2-eGFP treatment improved fasting blood glucose but had no effect on any of the other parameters. CONCLUSIONS These findings identify ACE2 as a novel target for the prevention of β-cell dysfunction and apoptosis occurring in type 2 diabetes.
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Affiliation(s)
- Sharell M. Bindom
- From the Department of Pharmacology and Experimental Therapeutics and the Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Chetan P. Hans
- From the Department of Pharmacology and Experimental Therapeutics and the Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Huijing Xia
- From the Department of Pharmacology and Experimental Therapeutics and the Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - A. Hamid Boulares
- From the Department of Pharmacology and Experimental Therapeutics and the Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana
| | - Eric Lazartigues
- From the Department of Pharmacology and Experimental Therapeutics and the Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana
- Corresponding author: Eric Lazartigues,
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Bernal-Mizrachi E, Cras-Méneur C, Ye BR, Johnson JD, Permutt MA. Transgenic overexpression of active calcineurin in beta-cells results in decreased beta-cell mass and hyperglycemia. PLoS One 2010; 5:e11969. [PMID: 20689817 PMCID: PMC2914754 DOI: 10.1371/journal.pone.0011969] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 07/09/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Glucose modulates beta-cell mass and function through an initial depolarization and Ca(2+) influx, which then triggers a number of growth regulating signaling pathways. One of the most important downstream effectors in Ca(2+) signaling is the calcium/Calmodulin activated serine threonine phosphatase, calcineurin. Recent evidence suggests that calcineurin/NFAT is essential for beta-cell proliferation, and that in its absence loss of beta-cells results in diabetes. We hypothesized that in contrast, activation of calcineurin might result in expansion of beta-cell mass and resistance to diabetes. METHODOLOGY/PRINCIPAL FINDINGS To determine the role of activation of calcineurin signaling in the regulation of pancreatic beta-cell mass and proliferation, we created mice that expressed a constitutively active form of calcineurin under the insulin gene promoter (caCn(RIP)). To our surprise, these mice exhibited glucose intolerance. In vitro studies demonstrated that while the second phase of Insulin secretion is enhanced, the overall insulin secretory response was conserved. Islet morphometric studies demonstrated decreased beta-cell mass suggesting that this was a major component responsible for altered Insulin secretion and glucose intolerance in caCn(RIP) mice. The reduced beta-cell mass was accompanied by decreased proliferation and enhanced apoptosis. CONCLUSIONS Our studies identify calcineurin as an important factor in controlling glucose homeostasis and indicate that chronic depolarization leading to increased calcineurin activity may contribute, along with other genetic and environmental factors, to beta-cell dysfunction and diabetes.
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Affiliation(s)
- Ernesto Bernal-Mizrachi
- Division of Metabolism, Endocrinology, Diabetes, The Brehm Center for Type 1 Diabetes, University of Michigan, Ann Arbor, Michigan, United States of America.
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Humphrey RK, Yu SM, Flores LE, Jhala US. Glucose regulates steady-state levels of PDX1 via the reciprocal actions of GSK3 and AKT kinases. J Biol Chem 2010; 285:3406-16. [PMID: 19833727 PMCID: PMC2823452 DOI: 10.1074/jbc.m109.006734] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 10/09/2009] [Indexed: 12/31/2022] Open
Abstract
The pancreatic beta cell is sensitive to even small changes in PDX1 protein levels; consequently, Pdx1 haploinsufficiency can inhibit beta cell growth and decrease insulin biosynthesis and gene expression, leading to compromised glucose-stimulated insulin secretion. Using metabolic labeling of primary islets and a cultured beta cell line, we show that glucose levels modulate PDX1 protein phosphorylation at a novel C-terminal GSK3 consensus that maps to serines 268 and 272. A decrease in glucose levels triggers increased turnover of the PDX1 protein in a GSK3-dependent manner, such that PDX1 phosphomutants are refractory to the destabilizing effect of low glucose. Glucose-stimulated activation of AKT and inhibition of GSK3 decrease PDX1 phosphorylation and delay degradation. Furthermore, direct pharmacologic inhibition of AKT destabilizes, and inhibition of GSK3 increases PDX1 protein stability. These studies define a novel functional role for the PDX1 C terminus in mediating the effects of glucose and demonstrate that glucose modulates PDX1 stability via the AKT-GSK3 axis.
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Affiliation(s)
- Rohan K. Humphrey
- From the Department of Pediatrics, University of California San Diego, La Jolla, California 92037
| | - Shu-Mei Yu
- From the Department of Pediatrics, University of California San Diego, La Jolla, California 92037
| | - Luis E. Flores
- From the Department of Pediatrics, University of California San Diego, La Jolla, California 92037
| | - Ulupi S. Jhala
- From the Department of Pediatrics, University of California San Diego, La Jolla, California 92037
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Jonas JC, Bensellam M, Duprez J, Elouil H, Guiot Y, Pascal SMA. Glucose regulation of islet stress responses and beta-cell failure in type 2 diabetes. Diabetes Obes Metab 2009; 11 Suppl 4:65-81. [PMID: 19817790 DOI: 10.1111/j.1463-1326.2009.01112.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pancreatic beta-cells exposed to high glucose concentrations display altered gene expression, function, survival and growth that may contribute to the slow deterioration of the functional beta-cell mass in type 2 diabetes. These glucotoxic alterations may result from various types of stress imposed by the hyperglycaemic environment, including oxidative stress, endoplasmic reticulum stress, cytokine-induced apoptosis and hypoxia. The glucose regulation of oxidative stress-response and integrated stress-response genes in cultured rat islets follows an asymmetric V-shaped profile parallel to that of beta-cell apoptosis, with a large increase at low glucose and a moderate increase at high vs. intermediate glucose concentrations. These observations suggest that both types of stress could play a role in the alteration of the functional beta-cell mass under states of prolonged hypoglycaemia and hyperglycaemia. In addition, beta-cell demise under glucotoxic conditions may also result from beta-cell hypoxia and, in vivo, from their exposure to inflammatory cytokines released locally by non-endocrine islet cells. A better understanding of the relative contribution of each type of stress to beta-cell glucotoxicity and of their pathophysiological cause in vivo may lead to new therapeutic strategies to prevent the slow deterioration of the functional beta-cell mass in glucose intolerant and type 2 diabetic patients.
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Affiliation(s)
- J C Jonas
- Université catholique de Louvain, Brussels, Belgium.
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Molina AJ, Wikstrom JD, Stiles L, Las G, Mohamed H, Elorza A, Walzer G, Twig G, Katz S, Corkey BE, Shirihai OS. Mitochondrial networking protects beta-cells from nutrient-induced apoptosis. Diabetes 2009; 58:2303-15. [PMID: 19581419 PMCID: PMC2750232 DOI: 10.2337/db07-1781] [Citation(s) in RCA: 296] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Previous studies have reported that beta-cell mitochondria exist as discrete organelles that exhibit heterogeneous bioenergetic capacity. To date, networking activity, and its role in mediating beta-cell mitochondrial morphology and function, remains unclear. In this article, we investigate beta-cell mitochondrial fusion and fission in detail and report alterations in response to various combinations of nutrients. RESEARCH DESIGN AND METHODS Using matrix-targeted photoactivatable green fluorescent protein, mitochondria were tagged and tracked in beta-cells within intact islets, as isolated cells and as cell lines, revealing frequent fusion and fission events. Manipulations of key mitochondrial dynamics proteins OPA1, DRP1, and Fis1 were tested for their role in beta-cell mitochondrial morphology. The combined effects of free fatty acid and glucose on beta-cell survival, function, and mitochondrial morphology were explored with relation to alterations in fusion and fission capacity. RESULTS beta-Cell mitochondria are constantly involved in fusion and fission activity that underlies the overall morphology of the organelle. We find that networking activity among mitochondria is capable of distributing a localized green fluorescent protein signal throughout an isolated beta-cell, a beta-cell within an islet, and an INS1 cell. Under noxious conditions, we find that beta-cell mitochondria become fragmented and lose their ability to undergo fusion. Interestingly, manipulations that shift the dynamic balance to favor fusion are able to prevent mitochondrial fragmentation, maintain mitochondrial dynamics, and prevent apoptosis. CONCLUSIONS These data suggest that alterations in mitochondrial fusion and fission play a critical role in nutrient-induced beta-cell apoptosis and may be involved in the pathophysiology of type 2 diabetes.
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Affiliation(s)
- Anthony J.A. Molina
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
| | - Jakob D. Wikstrom
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
- The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden
| | - Linsey Stiles
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts
| | - Guy Las
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
| | - Hibo Mohamed
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts
| | - Alvaro Elorza
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
| | - Gil Walzer
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts
| | - Gilad Twig
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
| | - Steve Katz
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts
| | - Barbara E. Corkey
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
| | - Orian S. Shirihai
- Department of Molecular Medicine, Obesity Research Center, Boston University School of Medicine, Boston, Massachusetts
- Corresponding author: Orian S. Shirihai,
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Wei P, Shi M, Barnum S, Cho H, Carlson T, Fraser JD. Effects of glucokinase activators GKA50 and LY2121260 on proliferation and apoptosis in pancreatic INS-1 beta cells. Diabetologia 2009; 52:2142-50. [PMID: 19641898 DOI: 10.1007/s00125-009-1446-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Accepted: 06/11/2009] [Indexed: 01/24/2023]
Abstract
AIMS/HYPOTHESIS Glucokinase (GK), an enzyme that phosphorylates glucose to form glucose 6-phosphate, serves as the glucose sensor that regulates insulin secretion in beta cells. GK activators (GKAs) activate GK via binding to an allosteric site of the enzyme. GKAs increase glucose-stimulated insulin secretion and decrease blood glucose levels. Using the differentiated beta cell line INS-1, we investigated the role of GKAs in promoting beta cell growth and survival and preventing beta cell apoptosis induced by chronic exposure to high levels of glucose. METHODS Proliferation was assessed using BrdU incorporation. Apoptosis was measured using caspase-3 activity. Immunoblot analysis was used to detect protein levels and the degree of phosphorylation. RESULTS The GK agonists GKA50 and LY2121260 increased both cell replication and cell numbers when tested at basal levels of glucose (3 mmol/l) in INS-1 cells. GKAs promoted INS-1 cell proliferation via upregulation of insulin receptor substrate-2 and subsequent activation of protein kinase B phosphorylation. GKA50 also prevented the INS-1 cell apoptosis that was induced by chronic high glucose conditions, probably via an increase in GK protein levels and normalisation of the apoptotic protein BCL2-associated agonist of cell death (BAD) and its phosphorylation. As a result of the reduction in cell apoptosis, GKA50 prevented cell loss and maintained glucose-stimulated insulin secretion. In addition, the anti-apoptotic activity of GKA50 was significantly abrogated by other GKAs that do not inhibit apoptosis, suggesting that direct binding of GKA50 to GK is essential for its anti-apoptotic effect. CONCLUSION/INTERPRETATION Our results suggest novel roles of GKAs in promoting beta cell growth and preventing chronic-hyperglycaemia-induced beta cell apoptosis. Thus, GKAs may provide novel therapeutics that increase beta cell mass to maintain euglycaemia in diabetes.
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Affiliation(s)
- P Wei
- Diabetes Biology Department, Pfizer Global Research and Development, La Jolla Laboratories, CA 92121, USA.
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Short-term modulation of extracellular signal-regulated kinase 1/2 and stress-activated protein kinase/c-Jun NH2-terminal kinase in pancreatic islets by glucose and palmitate: possible involvement of ceramide. Pancreas 2009; 38:585-92. [PMID: 19295452 DOI: 10.1097/mpa.0b013e31819fef03] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES The effect of glucose and palmitate on the phosphorylation of proteins associated with cell growth and survival (extracellular signal-regulated kinase 1/2 [ERK1/2] and stress-activated protein kinase/c-Jun NH2-terminal kinase [SAPK/JNK]) and on the expression of immediate early genes was investigated. METHODS Groups of freshly isolated rat pancreatic islets were incubated in 10-mmol/L glucose with palmitate, LY294002, or fumonisin B1 for the measurement of the phosphorylation and the content of ERK1/2, JNK/SAPK, and v-akt murine thymoma viral oncongene (AKT) (serine 473) by immunoblotting. The expressions of the immediate early genes, c-fos and c-jun, were evaluated by reverse transcription-polymerase chain reaction. RESULTS Glucose at 10 mmol/L induced ERK1/2 and AKT phosphorylations and decreased SAPK/JNK phosphorylation. Palmitate (0.1 mmol/L) abolished the glucose effect on ERK1/2, AKT, and SAPK/JNK phosphorylations. LY294002 caused a similar effect. The inhibitory effect of palmitate on glucose-induced ERK1/2 and AKT phosphorylation changes was not observed in the presence of fumonisin B1. Glucose increased c-fos and decreased c-jun expressions. Palmitate and LY294002 abolished these latter glucose effects. The presence of fumonisin B1 abolished the effect induced by palmitate on c-jun expression. CONCLUSIONS Our results suggest that short-term changes of mitogen-activated protein kinase and AKT signaling pathways and c-fos and c-jun expressions caused by glucose are abolished by palmitate through phosphatidylinositol 3-kinase inhibition via ceramide synthesis.
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Elghazi L, Bernal-Mizrachi E. Akt and PTEN: beta-cell mass and pancreas plasticity. Trends Endocrinol Metab 2009; 20:243-51. [PMID: 19541499 PMCID: PMC4456182 DOI: 10.1016/j.tem.2009.03.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 03/02/2009] [Accepted: 03/03/2009] [Indexed: 12/31/2022]
Abstract
The capacity of pancreatic beta-cells to adapt to insulin resistance is crucial for glucose homeostasis and is a factor in the development of type 2 diabetes. The insulin receptor substrate (insulin receptor 2/phosphoinositide 3-kinase [PI3K]) pathway plays a crucial part in regulating beta-cell mass and function. The serine-threonine kinase Akt, also known as protein kinase B, is one of the major downstream targets of the PI3K pathway and is negatively regulated by phosphatase and tensin homologue deleted on chromosome 10. This Akt signaling pathway has recently been implicated in cell-cycle progression and survival of pancreatic beta-cells. Understanding the mechanisms that link Akt to modulation of beta-cell mass, function and plasticity will positively affect treatment of human diabetes.
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Affiliation(s)
- Lynda Elghazi
- Department of Internal Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine Saint-Louis, MO 63110, USA
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Sachdeva MM, Stoffers DA. Minireview: Meeting the demand for insulin: molecular mechanisms of adaptive postnatal beta-cell mass expansion. Mol Endocrinol 2009; 23:747-58. [PMID: 19196831 DOI: 10.1210/me.2008-0400] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Type 2 diabetes results from pancreatic ss-cell failure in the setting of insulin resistance. This model of disease progression has received recent support from the results of genome-wide association studies that identify genes potentially regulating ss-cell growth and function as type 2 diabetes susceptibility loci. Normal ss-cell compensation for an increased insulin demand includes both enhanced insulin-secretory capacity and an expansion of morphological ss-cell mass, due largely to changes in the balance between ss-cell proliferation and apoptosis. Recent years have brought significant progress in the understanding of both extrinsic signals stimulating ss-cell growth as well as mediators intrinsic to the ss-cell that regulate the compensatory response. Here, we review the current knowledge of mechanisms underlying adaptive expansion of ss-cell mass, focusing on lessons learned from experimental models of physiologically occurring insulin-resistant states including diet-induced obesity and pregnancy, and highlighting the potential importance of interorgan cross talk. The identification of critical mediators of islet compensation may direct the development of future therapeutic strategies to enhance the response of ss-cells to insulin resistance.
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Affiliation(s)
- Mira M Sachdeva
- Department of Medicine, Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA
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Lee YC, Nielsen JH. Regulation of beta cell replication. Mol Cell Endocrinol 2009; 297:18-27. [PMID: 18824066 DOI: 10.1016/j.mce.2008.08.033] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 08/24/2008] [Accepted: 08/24/2008] [Indexed: 10/21/2022]
Abstract
Beta cell mass, at any given time, is governed by cell differentiation, neogenesis, increased or decreased cell size (cell hypertrophy or atrophy), cell death (apoptosis), and beta cell proliferation. Nutrients, hormones and growth factors coupled with their signalling intermediates have been suggested to play a role in beta cell mass regulation. In addition, genetic mouse model studies have indicated that cyclins and cyclin-dependent kinases that determine cell cycle progression are involved in beta cell replication, and more recently, menin in association with cyclin-dependent kinase inhibitors has been demonstrated to be important in beta cell growth. In this review, we consider and highlight some aspects of cell cycle regulation in relation to beta cell replication. The role of cell cycle regulation in beta cell replication is mostly from studies in rodent models, but whether these findings can be extended to human beta cells remains to be shown.
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Affiliation(s)
- Ying C Lee
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, Building 6.5, DK-2200 Copenhagen N., Denmark
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Abstract
The appropriate function of insulin-producing pancreatic beta-cells is crucial for the regulation of glucose homeostasis, and its impairment leads to diabetes mellitus, the most common metabolic disorder in man. In addition to glucose, the major nutrient factor, inputs from the nervous system, humoral components, and cell-cell communication within the islet of Langerhans act together to guarantee the release of appropriate amounts of insulin in response to changes in blood glucose levels. Data obtained within the past decade in several laboratories have revitalized controversy over the autocrine feedback action of secreted insulin on beta-cell function. Although insulin historically has been suggested to exert a negative effect on beta-cells, recent data provide evidence for a positive role of insulin in transcription, translation, ion flux, insulin secretion, proliferation, and beta-cell survival. Current insights on the role of insulin on pancreatic beta-cell function are discussed.
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Affiliation(s)
- Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden.
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Bates HE, Sirek A, Kiraly MA, Yue JTY, Riddell MC, Matthews SG, Vranic M. Adaptation to intermittent stress promotes maintenance of beta-cell compensation: comparison with food restriction. Am J Physiol Endocrinol Metab 2008; 295:E947-58. [PMID: 18713962 DOI: 10.1152/ajpendo.90378.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Intermittent restraint stress delays hyperglycemia in ZDF rats better than pair feeding. We hypothesized that intermittent stress would preserve beta-cell mass through distinct mechanisms from food restriction. We studied temporal effects of intermittent stress on beta-cell compensation during pre-, early, and late diabetes. Six-week-old obese male ZDF rats were restraint-stressed 1 h/day, 5 days/wk for 0, 3, 6, or 13 wk and compared with age-matched obese ZDF rats that had been food restricted for 13 wk, and 19-wk-old lean ZDF rats. Thirteen weeks of stress and food restriction lowered cumulative food intake 10-15%. Obese islets were fibrotic and disorganized and not improved by stress or food restriction. Obese pancreata had islet hyperplasia and showed evidence of neogenesis, but by 19 wk old beta-cell mass was not increased, and islets had fewer beta-cells that were hypertrophic. Both stress and food restriction partially preserved beta-cell mass at 19 wk old via islet hypertrophy, whereas stress additionally lowered alpha-cell mass. Concomitant with maintenance of insulin responses to glucose, stress delayed the sixfold decline in beta-cell proliferation and reduced beta-cell hypertrophy, translating into 30% more beta-cells per islet after 13 wk. In contrast, food restriction did not improve insulin responses or beta-cell hyperplasia, exacerbated beta-cell hypertrophy, and resulted in fewer beta-cells and greater alpha-cell mass than with stress. Thus, preservation of beta-cell mass with adaptation to intermittent stress is related to beta-cell hyperplasia, maintenance of insulin responses to glucose, and reductions in alpha-cell mass that do not occur with food restriction.
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Affiliation(s)
- Holly E Bates
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
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El Ouaamari A, Baroukh N, Martens GA, Lebrun P, Pipeleers D, van Obberghen E. miR-375 targets 3'-phosphoinositide-dependent protein kinase-1 and regulates glucose-induced biological responses in pancreatic beta-cells. Diabetes 2008; 57:2708-17. [PMID: 18591395 PMCID: PMC2551681 DOI: 10.2337/db07-1614] [Citation(s) in RCA: 339] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE MicroRNAs are short, noncoding RNAs that regulate gene expression. We hypothesized that the phosphatidylinositol 3-kinase (PI 3-kinase) cascade known to be important in beta-cell physiology could be regulated by microRNAs. Here, we focused on the pancreas-specific miR-375 as a potential regulator of its predicted target 3'-phosphoinositide-dependent protein kinase-1 (PDK1), and we analyzed its implication in the response of insulin-producing cells to elevation of glucose levels. RESEARCH DESIGN AND METHODS We used insulinoma-1E cells to analyze the effects of miR-375 on PDK1 protein level and downstream signaling using Western blotting, glucose-induced insulin gene expression using quantitative RT-PCR, and DNA synthesis by measuring thymidine incorporation. Moreover, we analyzed the effect of glucose on miR-375 expression in both INS-1E cells and primary rat islets. Finally, miR-375 expression in isolated islets was analyzed in diabetic Goto-Kakizaki (GK) rats. RESULTS We found that miR-375 directly targets PDK1 and reduces its protein level, resulting in decreased glucose-stimulatory action on insulin gene expression and DNA synthesis. Furthermore, glucose leads to a decrease in miR-375 precursor level and a concomitant increase in PDK1 protein. Importantly, regulation of miR-375 expression by glucose occurs in primary rat islets as well. Finally, miR-375 expression was found to be decreased in fed diabetic GK rat islets. CONCLUSIONS Our findings provide evidence for a role of a pancreatic-specific microRNA, miR-375, in the regulation of PDK1, a key molecule in PI 3-kinase signaling in pancreatic beta-cells. The effects of glucose on miR-375 are compatible with the idea that miR-375 is involved in glucose regulation of insulin gene expression and beta-cell growth.
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Abstract
The healthy beta-cell has an enormous capacity to adapt to conditions of higher insulin demand (e.g. in obesity, pregnancy, cortisol excess) to maintain normoglycaemia with an increase in its functional beta-cell mass. This compensates in 80-90% of individuals for insulin resistance. However, in 10-20% of individuals, the beta-cells are unable to match the demands of insulin resistance and insulin levels are relatively insufficient to maintain normal glycaemic control. This eventually leads to glucose intolerance and type 2 diabetes (T2DM). Accordingly, preservation of functional beta-cell mass has become central in the treatment of type 1 diabetes as well as T2DM. The purpose of this review is to summarize the recently described mechanisms of beta-cell death in T2DM and to postulate possible new targets for treatment.
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Affiliation(s)
- Kathrin Maedler
- Department of Medicine, Larry L. Hillblom Islet Research Center, University of California at Los Angeles, Los Angeles, CA 90095-7345, USA.
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