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Yoo HS, Moss KO, Cockrum MA, Woo W, Napoli JL. Energy status regulates levels of the RAR/RXR ligand 9-cis-retinoic acid in mammalian tissues: Glucose reduces its synthesis in β-cells. J Biol Chem 2023; 299:105255. [PMID: 37714463 PMCID: PMC10582780 DOI: 10.1016/j.jbc.2023.105255] [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: 08/05/2023] [Revised: 09/01/2023] [Accepted: 09/10/2023] [Indexed: 09/17/2023] Open
Abstract
9-cis-retinoic acid (9cRA) binds retinoic acid receptors (RAR) and retinoid X receptors (RXR) with nanomolar affinities, in contrast to all-trans-retinoic acid (atRA), which binds only RAR with nanomolar affinities. RXR heterodimerize with type II nuclear receptors, including RAR, to regulate a vast gene array. Despite much effort, 9cRA has not been identified as an endogenous retinoid, other than in pancreas. By revising tissue analysis methods, 9cRA quantification by liquid chromatography-tandem mass spectrometry becomes possible in all mouse tissues analyzed. 9cRA occurs in concentrations similar to or greater than atRA. Fasting increases 9cRA in white and brown adipose, brain and pancreas, while increasing atRA in white adipose, liver and pancreas. 9cRA supports FoxO1 actions in pancreas β-cells and counteracts glucose actions that lead to glucotoxicity; in part by inducing Atg7 mRNA, which encodes the key enzyme essential for autophagy. Glucose suppresses 9cRA biosynthesis in the β-cell lines 832/13 and MIN6. Glucose reduces 9cRA biosynthesis in 832/13 cells by inhibiting Rdh5 transcription, unconnected to insulin, through cAMP and Akt, and inhibiting FoxO1. Through adapting tissue specifically to fasting, 9cRA would act independent of atRA. Widespread occurrence of 9cRA in vivo, and its self-sufficient adaptation to energy status, provides new perspectives into regulation of energy balance, attenuation of insulin and glucose actions, regulation of type II nuclear receptors, and retinoid biology.
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Affiliation(s)
- Hong Sik Yoo
- Department of Nutritional Sciences and Toxicology, Graduate Program in Metabolic Biology, University of California, Berkeley, Berkeley, California, USA
| | - Kristin Obrochta Moss
- Department of Nutritional Sciences and Toxicology, Graduate Program in Metabolic Biology, University of California, Berkeley, Berkeley, California, USA
| | - Michael A Cockrum
- Department of Nutritional Sciences and Toxicology, Graduate Program in Metabolic Biology, University of California, Berkeley, Berkeley, California, USA
| | - Wonsik Woo
- Department of Nutritional Sciences and Toxicology, Graduate Program in Metabolic Biology, University of California, Berkeley, Berkeley, California, USA
| | - Joseph L Napoli
- Department of Nutritional Sciences and Toxicology, Graduate Program in Metabolic Biology, University of California, Berkeley, Berkeley, California, USA.
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2
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Sánchez-Jasso DE, López-Guzmán SF, Bermúdez-Cruz RM, Oviedo N. Novel Aspects of cAMP-Response Element Modulator (CREM) Role in Spermatogenesis and Male Fertility. Int J Mol Sci 2023; 24:12558. [PMID: 37628737 PMCID: PMC10454534 DOI: 10.3390/ijms241612558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/27/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Spermatogenesis is a very complex process with an intricate transcriptional regulation. The transition from the diploid to the haploid state requires the involvement of specialized genes in meiosis, among other specific functions for the formation of the spermatozoon. The transcription factor cAMP-response element modulator (CREM) is a key modulator that triggers the differentiation of the germ cell into the spermatozoon through the modification of gene expression. CREM has multiple repressor and activator isoforms whose expression is tissue-cell-type specific and tightly regulated by various factors at the transcriptional, post-transcriptional and post-translational level. The activator isoform CREMτ controls the expression of several relevant genes in post-meiotic stages of spermatogenesis. In addition, exposure to xenobiotics negatively affects CREMτ expression, which is linked to male infertility. On the other hand, antioxidants could have a positive effect on CREMτ expression and improve sperm parameters in idiopathically infertile men. Therefore, CREM expression could be used as a biomarker to detect and even counteract male infertility. This review examines the importance of CREM as a transcription factor for sperm production and its relevance in male fertility, infertility and the response to environmental xenobiotics that may affect CREMτ expression and the downstream regulation that alters male fertility. Also, some health disorders in which CREM expression is altered are discussed.
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Affiliation(s)
- Diego Eduardo Sánchez-Jasso
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City 07360, Mexico; (D.E.S.-J.); (S.F.L.-G.); (R.M.B.-C.)
| | - Sergio Federico López-Guzmán
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City 07360, Mexico; (D.E.S.-J.); (S.F.L.-G.); (R.M.B.-C.)
| | - Rosa Maria Bermúdez-Cruz
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), Mexico City 07360, Mexico; (D.E.S.-J.); (S.F.L.-G.); (R.M.B.-C.)
| | - Norma Oviedo
- Unidad de Investigación Médica en Immunología e Infectología, Centro Médico Nacional La Raza, Instituto Mexicano del Seguro Social (IMSS), Mexico City 02990, Mexico
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Keller DM, Perez IG. Dual regulation of miR-375 and CREM genes in pancreatic beta cells. Islets 2022; 14:139-148. [PMID: 35377267 PMCID: PMC8986308 DOI: 10.1080/19382014.2022.2060688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
MicroRNA-375 (miR-375) is upregulated in the islets of some diabetics and is correlated with poor outcome. Previous work in our laboratory showed that cyclic adenosine monophosphate (cAMP) reduces miR-375 expression and could provide a way to restore normal miR-375 levels, however the transcription repression mechanism is unknown. Using a chromatin immunoprecipitation assay we show that cAMP response element modulator (CREM) binds to the miR-375 promoter 3-fold above background and we find that CREM represses transcription from the miR-375 promoter 1.8-fold. While investigating miR-375 target genes we discovered that several microRNA:mRNA target prediction algorithms listed human CREM as a target gene of miR-375. The predicted binding site is conserved in primates but not in other species. We found that indeed miR-375 binds to the predicted site on human CREM and represses translation of a green fluorescent protein reporter gene by 30%. These findings suggest a primate-specific double-negative feedback loop, a mechanism that would keep these important β-cell regulators in check.
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Affiliation(s)
- David M. Keller
- Department of Biological Sciences, California State University Chico, Chico, CA, USA
- CONTACT David M. Keller Department of Biological Sciences, California State University, Chico, 900 W. 1st St, Chico, CA95929 linkedin.com/in/keller-david-6529485b
| | - Isis G. Perez
- Department of Biological Sciences, California State University Chico, Chico, CA, USA
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4
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Tajbakhsh A, Gheibihayat SM, Askari H, Savardashtaki A, Pirro M, Johnston TP, Sahebkar A. Statin-regulated phagocytosis and efferocytosis in physiological and pathological conditions. Pharmacol Ther 2022; 238:108282. [DOI: 10.1016/j.pharmthera.2022.108282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 09/10/2022] [Accepted: 09/13/2022] [Indexed: 10/14/2022]
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Izumi T. In vivo Roles of Rab27 and Its Effectors in Exocytosis. Cell Struct Funct 2021; 46:79-94. [PMID: 34483204 PMCID: PMC10511049 DOI: 10.1247/csf.21043] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 08/31/2021] [Indexed: 11/11/2022] Open
Abstract
The monomeric GTPase Rab27 regulates exocytosis of a broad range of vesicles in multicellular organisms. Several effectors bind GTP-bound Rab27a and/or Rab27b on secretory vesicles to execute a series of exocytic steps, such as vesicle maturation, movement along microtubules, anchoring within the peripheral F-actin network, and tethering to the plasma membrane, via interactions with specific proteins and membrane lipids in a local milieu. Although Rab27 effectors generally promote exocytosis, they can also temporarily restrict it when they are involved in the rate-limiting step. Genetic alterations in Rab27-related molecules cause discrete diseases manifesting pigment dilution and immunodeficiency, and can also affect common diseases such as diabetes and cancer in complex ways. Although the function and mechanism of action of these effectors have been explored, it is unclear how multiple effectors act in coordination within a cell to regulate the secretory process as a whole. It seems that Rab27 and various effectors constitutively reside on individual vesicles to perform consecutive exocytic steps. The present review describes the unique properties and in vivo roles of the Rab27 system, and the functional relationship among different effectors coexpressed in single cells, with pancreatic beta cells used as an example.Key words: membrane trafficking, regulated exocytosis, insulin granules, pancreatic beta cells.
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Affiliation(s)
- Tetsuro Izumi
- Laboratory of Molecular Endocrinology and Metabolism, Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8512, Japan
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Gendaszewska-Darmach E, Garstka MA, Błażewska KM. Targeting Small GTPases and Their Prenylation in Diabetes Mellitus. J Med Chem 2021; 64:9677-9710. [PMID: 34236862 PMCID: PMC8389838 DOI: 10.1021/acs.jmedchem.1c00410] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
A fundamental role
of pancreatic β-cells to maintain proper
blood glucose level is controlled by the Ras superfamily of small
GTPases that undergo post-translational modifications, including prenylation.
This covalent attachment with either a farnesyl or a geranylgeranyl
group controls their localization, activity, and protein–protein
interactions. Small GTPases are critical in maintaining glucose homeostasis
acting in the pancreas and metabolically active tissues such as skeletal
muscles, liver, or adipocytes. Hyperglycemia-induced upregulation
of small GTPases suggests that inhibition of these pathways deserves
to be considered as a potential therapeutic approach in treating T2D.
This Perspective presents how inhibition of various points in the
mevalonate pathway might affect protein prenylation and functioning
of diabetes-affected tissues and contribute to chronic inflammation
involved in diabetes mellitus (T2D) development. We also demonstrate
the currently available molecular tools to decipher the mechanisms
linking the mevalonate pathway’s enzymes and GTPases with diabetes.
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Affiliation(s)
- Edyta Gendaszewska-Darmach
- Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego Street 4/10, 90-924 Łódź, Poland
| | - Malgorzata A Garstka
- Core Research Laboratory, Department of Endocrinology, Department of Tumor and Immunology, Precision Medical Institute, Western China Science and Technology Innovation Port, School of Medicine, the Second Affiliated Hospital of Xi'an Jiaotong University, DaMingGong, Jian Qiang Road, Wei Yang district, Xi'an 710016, China
| | - Katarzyna M Błażewska
- Institute of Organic Chemistry, Faculty of Chemistry, Lodz University of Technology, Żeromskiego Street 116, 90-924 Łódź, Poland
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Daziano G, Blondeau N, Béraud-Dufour S, Abderrahmani A, Rovère C, Heurteaux C, Mazella J, Lebrun P, Coppola T. Sortilin-derived peptides promote pancreatic beta-cell survival through CREB signaling pathway. Pharmacol Res 2021; 167:105539. [PMID: 33737242 DOI: 10.1016/j.phrs.2021.105539] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/24/2021] [Accepted: 03/04/2021] [Indexed: 12/25/2022]
Abstract
Deterioration of insulin secretion and pancreatic beta-cell mass by inflammatory attacks is one of the main pathophysiological features of type 2 diabetes (T2D). Therefore, preserving beta-cell mass and stimulating insulin secretion only in response to glucose for avoiding the hypoglycemia risks, are the most state-of-the-art option for the treatment of T2D. In this study we tested two correlated hypothesis that 1/ the endogenous peptide released from sortilin, known as PE, that stimulates insulin secretion only in response to glucose, protects beta-cells against death induced by cytokines, and 2/ Spadin and Mini-Spadin, two synthetic peptides derived from PE, that mimic the effects of PE in insulin secretion, also provide beneficial effect on beta-cells survival. We show that PE and its derivatives by inducing a rise of intracellular calcium concentration by depolarizing the membrane protect beta-cells against death induced by Interleukin-1β. Using biochemical, confocal imaging and cell biology techniques, we reveal that the protective effects of PE and its derivatives rely on the activation of the CaM-Kinase pathway, and on the phosphorylation and activation of the transcription factor CREB. In addition, Mini-Spadin promotes beta-cell proliferation, suggesting its possible regenerative effect. This study highlights new possible roles of PE in pancreatic beta-cell survival and its derivatives as pharmacological tools against diabetes.
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Affiliation(s)
- Guillaume Daziano
- Université Côte d'Azur, CNRS, IPMC, Sophia Antipolis, F-06560, France
| | - Nicolas Blondeau
- Université Côte d'Azur, CNRS, IPMC, Sophia Antipolis, F-06560, France
| | | | - Amar Abderrahmani
- Université Lille, CNRS, Centrale Lille, Université Polytechnique Hauts-de-France, UMR 8520-IEMN, F-59000 Lille, France
| | - Carole Rovère
- Université Côte d'Azur, CNRS, IPMC, Sophia Antipolis, F-06560, France
| | | | - Jean Mazella
- Université Côte d'Azur, CNRS, IPMC, Sophia Antipolis, F-06560, France
| | - Patricia Lebrun
- Université Côte d'Azur, CNRS, IPMC, Sophia Antipolis, F-06560, France.
| | - Thierry Coppola
- Université Côte d'Azur, CNRS, IPMC, Sophia Antipolis, F-06560, France.
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Coppola T, Beraud-Dufour S, Lebrun P, Blondeau N. Bridging the Gap Between Diabetes and Stroke in Search of High Clinical Relevance Therapeutic Targets. Neuromolecular Med 2019; 21:432-444. [PMID: 31489567 DOI: 10.1007/s12017-019-08563-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 08/13/2019] [Indexed: 12/20/2022]
Abstract
Diabetes affects more than 425 million people worldwide, a scale approaching pandemic proportion. Diabetes represents a major risk factor for stroke, and therefore is actively addressed for stroke prevention. However, how diabetes affects stroke severity has not yet been extensively considered, which is surprising given the evident but understudied common mechanistic features of both pathologies. The increase in number of diabetic people, incidence of stroke in the presence of this specific risk factor, and the exacerbation of ischemic brain damage in diabetic conditions (at least in animal models) warrants the need to integrate this comorbidity in preclinical studies of brain ischemia to develop novel therapeutic approaches. Therefore, a better understanding of the commonalties involved in the course of both diseases would offer the promise of discovering novel neuroprotective pathways that would be more appropriated to clinical scenarios. In this article, we will review the relevant mechanisms that have been identified as common traits of both pathologies and that could be, to our knowledge, potential targets in both pathologies.
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Affiliation(s)
- Thierry Coppola
- Université Côte d'Azur, CNRS, IPMC, 660 route des Lucioles, 06560, Valbonne, France.
| | - Sophie Beraud-Dufour
- Université Côte d'Azur, CNRS, IPMC, 660 route des Lucioles, 06560, Valbonne, France
| | - Patricia Lebrun
- Université Côte d'Azur, CNRS, IPMC, 660 route des Lucioles, 06560, Valbonne, France
| | - Nicolas Blondeau
- Université Côte d'Azur, CNRS, IPMC, 660 route des Lucioles, 06560, Valbonne, France.
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Brajkovic S, Ferdaoussi M, Pawlowski V, Ezanno H, Plaisance V, Zmuda E, Hai T, Annicotte JS, Waeber G, Abderrahmani A. Islet Brain 1 Protects Insulin Producing Cells against Lipotoxicity. J Diabetes Res 2016; 2016:9158562. [PMID: 26665154 PMCID: PMC4655268 DOI: 10.1155/2016/9158562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/06/2015] [Indexed: 01/09/2023] Open
Abstract
Chronic intake of saturated free fatty acids is associated with diabetes and may contribute to the impairment of functional beta cell mass. Mitogen activated protein kinase 8 interacting protein 1 also called islet brain 1 (IB1) is a candidate gene for diabetes that is required for beta cell survival and glucose-induced insulin secretion (GSIS). In this study we investigated whether IB1 expression is required for preserving beta cell survival and function in response to palmitate. Chronic exposure of MIN6 and isolated rat islets cells to palmitate led to reduction of the IB1 mRNA and protein content. Diminution of IB1 mRNA and protein level relied on the inducible cAMP early repressor activity and proteasome-mediated degradation, respectively. Suppression of IB1 level mimicked the harmful effects of palmitate on the beta cell survival and GSIS. Conversely, ectopic expression of IB1 counteracted the deleterious effects of palmitate on the beta cell survival and insulin secretion. These findings highlight the importance in preserving the IB1 content for protecting beta cell against lipotoxicity in diabetes.
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Affiliation(s)
- Saška Brajkovic
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland
- University of Lille, European Genomic Institute for Diabetes (EGID) FR 3508, UMR CNRS 8199, Faculty of Medicine West, 1 place de Verdun, 59045 Lille, France
| | - Mourad Ferdaoussi
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland
- University of Lille, European Genomic Institute for Diabetes (EGID) FR 3508, UMR CNRS 8199, Faculty of Medicine West, 1 place de Verdun, 59045 Lille, France
- Department of Pharmacology and the Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Valérie Pawlowski
- University of Lille, European Genomic Institute for Diabetes (EGID) FR 3508, UMR CNRS 8199, Faculty of Medicine West, 1 place de Verdun, 59045 Lille, France
- University of Lille, EGID FR 3508, Department of Endocrine Surgery, Lille University Hospital, UMR INSERM 1190, Lille, France
| | - Hélène Ezanno
- University of Lille, European Genomic Institute for Diabetes (EGID) FR 3508, UMR CNRS 8199, Faculty of Medicine West, 1 place de Verdun, 59045 Lille, France
| | - Valérie Plaisance
- University of Lille, European Genomic Institute for Diabetes (EGID) FR 3508, UMR CNRS 8199, Faculty of Medicine West, 1 place de Verdun, 59045 Lille, France
| | - Erik Zmuda
- Department of Molecular and Cellular Biochemistry, Ohio State University, 1060 Carmack Road, Columbus, OH, USA
| | - Tsonwin Hai
- Department of Molecular and Cellular Biochemistry, Ohio State University, 1060 Carmack Road, Columbus, OH, USA
| | - Jean-Sébastien Annicotte
- University of Lille, European Genomic Institute for Diabetes (EGID) FR 3508, UMR CNRS 8199, Faculty of Medicine West, 1 place de Verdun, 59045 Lille, France
| | - Gérard Waeber
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland
| | - Amar Abderrahmani
- University of Lille, European Genomic Institute for Diabetes (EGID) FR 3508, UMR CNRS 8199, Faculty of Medicine West, 1 place de Verdun, 59045 Lille, France
- *Amar Abderrahmani:
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Heo KS, Cushman HJ, Akaike M, Woo CH, Wang X, Qiu X, Fujiwara K, Abe JI. ERK5 activation in macrophages promotes efferocytosis and inhibits atherosclerosis. Circulation 2014; 130:180-91. [PMID: 25001623 DOI: 10.1161/circulationaha.113.005991] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Efferocytosis is a process by which dead and dying cells are removed by phagocytic cells. Efferocytosis by macrophages is thought to curb the progression of atherosclerosis, but the mechanistic insight of this process is lacking. METHODS AND RESULTS When macrophages were fed apoptotic cells or treated with pitavastatin in vitro, efferocytosis-related signaling and phagocytic capacity were upregulated in an ERK5 activity-dependent manner. Macrophages isolated from macrophage-specific ERK5-null mice exhibited reduced efferocytosis and levels of gene and protein expression of efferocytosis-related molecules. When these mice were crossed with low-density lipoprotein receptor(-/-) mice and fed a high-cholesterol diet, atherosclerotic plaque formation was accelerated, and the plaques had more advanced and vulnerable morphology. CONCLUSIONS Our results demonstrate that ERK5, which is robustly activated by statins, is a hub molecule that upregulates macrophage efferocytosis, thereby suppressing atherosclerotic plaque formation. Molecules that upregulate ERK5 and its signaling in macrophages may be good drug targets for suppressing cardiovascular diseases.
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Affiliation(s)
- Kyung-Sun Heo
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.).
| | - Hannah J Cushman
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.)
| | - Masashi Akaike
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.)
| | - Chang-Hoon Woo
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.)
| | - Xin Wang
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.)
| | - Xing Qiu
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.)
| | - Keigi Fujiwara
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.)
| | - Jun-ichi Abe
- From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY (K.H., H.J.C., C.W., K.F., J.A.); Department of Medical Education, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan (M.A.); Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom (X.W.); and Biostatistics and Computational Biology, University of Rochester School of Medicine and Dentistry, Rochester, NY (X.Q.).
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Salvi R, Abderrahmani A. Decompensation of β-cells in diabetes: when pancreatic β-cells are on ICE(R). J Diabetes Res 2014; 2014:768024. [PMID: 24672804 PMCID: PMC3941242 DOI: 10.1155/2014/768024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/03/2014] [Indexed: 01/05/2023] Open
Abstract
Insulin production and secretion are temporally regulated. Keeping insulin secretion at rest after a rise of glucose prevents exhaustion and ultimately failure of β-cells. Among the mechanisms that reduce β-cell activity is the inducible cAMP early repressor (ICER). ICER is an immediate early gene, which is rapidly induced by the cyclic AMP (cAMP) signaling cascade. The seminal function of ICER is to negatively regulate the production and secretion of insulin by repressing the genes expression. This is part of adaptive response required for proper β-cells function in response to environmental factors. Inappropriate induction of ICER accounts for pancreatic β-cells dysfunction and ultimately death elicited by chronic hyperglycemia, fatty acids, and oxidized LDL. This review underlines the importance of balancing the negative regulation achieved by ICER for preserving β-cell function and survival in diabetes.
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Affiliation(s)
- Roberto Salvi
- European Genomic Institute for Diabetes (EGID), Lille 2 University, UMR 8199, 3508 Lille, France
| | - Amar Abderrahmani
- European Genomic Institute for Diabetes (EGID), Lille 2 University, UMR 8199, 3508 Lille, France
- Faculty of Medicine West, 1 Place de Verdun, 59045 Lille, France
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Ezanno H, Pawlowski V, Abdelli S, Boutry R, Gmyr V, Kerr-Conte J, Bonny C, Pattou F, Abderrahmani A. JNK3 is required for the cytoprotective effect of exendin 4. J Diabetes Res 2014; 2014:814854. [PMID: 25025079 PMCID: PMC4083605 DOI: 10.1155/2014/814854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 05/13/2014] [Accepted: 05/27/2014] [Indexed: 12/26/2022] Open
Abstract
Preservation of beta cell against apoptosis is one of the therapeutic benefits of the glucagon-like peptide-1 (GLP1) antidiabetic mimetics for preserving the functional beta cell mass exposed to diabetogenic condition including proinflammatory cytokines. The mitogen activated protein kinase 10 also called c-jun amino-terminal kinase 3 (JNK3) plays a protective role in insulin-secreting cells against death caused by cytokines. In this study, we investigated whether the JNK3 expression is associated with the protective effect elicited by the GLP1 mimetic exendin 4. We found an increase in the abundance of JNK3 in isolated human islets and INS-1E cells cultured with exendin 4. Induction of JNK3 by exendin 4 was associated with an increased survival of INS-1E cells. Silencing of JNK3 prevented the cytoprotective effect of exendin 4 against apoptosis elicited by culture condition and cytokines. These results emphasize the requirement of JNK3 in the antiapoptotic effects of exendin 4.
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Affiliation(s)
- Hélène Ezanno
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
| | - Valérie Pawlowski
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Saida Abdelli
- Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, 1011 Lausanne, Switzerland
| | - Raphael Boutry
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
| | - Valery Gmyr
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Julie Kerr-Conte
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Christophe Bonny
- Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, 1011 Lausanne, Switzerland
| | - François Pattou
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Amar Abderrahmani
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
- *Amar Abderrahmani:
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Ljubicic S, Bezzi P, Brajkovic S, Nesca V, Guay C, Ohbayashi N, Fukuda M, Abderrhamani A, Regazzi R. The GTPase Rab37 Participates in the Control of Insulin Exocytosis. PLoS One 2013; 8:e68255. [PMID: 23826383 PMCID: PMC3694898 DOI: 10.1371/journal.pone.0068255] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 05/27/2013] [Indexed: 01/04/2023] Open
Abstract
Rab37 belongs to a subclass of Rab GTPases regulating exocytosis, including also Rab3a and Rab27a. Proteomic studies indicate that Rab37 is associated with insulin-containing large dense core granules of pancreatic β-cells. In agreement with these observations, we detected Rab37 in extracts of β-cell lines and human pancreatic islets and confirmed by confocal microscopy the localization of the GTPase on insulin-containing secretory granules. We found that, as is the case for Rab3a and Rab27a, reduction of Rab37 levels by RNA interference leads to impairment in glucose-induced insulin secretion and to a decrease in the number of granules in close apposition to the plasma membrane. Pull-down experiments revealed that, despite similar functional effects, Rab37 does not interact with known Rab3a or Rab27a effectors and is likely to operate through a different mechanism. Exposure of insulin-secreting cells to proinflammatory cytokines, fatty acids or oxidized low-density lipoproteins, mimicking physiopathological conditions that favor the development of diabetes, resulted in a decrease in Rab37 expression. Our data identify Rab37 as an additional component of the machinery governing exocytosis of β-cells and suggest that impaired expression of this GTPase may contribute to defective insulin release in pre-diabetic and diabetic conditions.
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Affiliation(s)
- Sanda Ljubicic
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Paola Bezzi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Saska Brajkovic
- EGID FR 3508, INSERM U859, Université de Lille 2, Lille, France
| | - Valeria Nesca
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Claudiane Guay
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Norihiko Ohbayashi
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | | | - Romano Regazzi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
- * E-mail:
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14
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Fukuda M. Rab27 effectors, pleiotropic regulators in secretory pathways. Traffic 2013; 14:949-63. [PMID: 23678941 DOI: 10.1111/tra.12083] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/13/2013] [Accepted: 05/16/2013] [Indexed: 12/18/2022]
Abstract
Rab27, a member of the small GTPase Rab family, is widely conserved in metazoan, and two Rab27 isoforms, Rab27A and Rab27B, are present in vertebrates. Rab27A was the first Rab protein whose dysfunction was found to cause a human hereditary disease, type 2 Griscelli syndrome, which is characterized by silvery hair and immunodeficiency. The discovery in the 21st century of three distinct types of mammalian Rab27A effectors [synaptotagmin-like protein (Slp), Slp homologue lacking C2 domains (Slac2), and Munc13-4] that specifically bind active Rab27A has greatly accelerated our understanding not only of the molecular mechanisms of Rab27A-mediated membrane traffic (e.g. melanosome transport and regulated secretion) but of the symptoms of Griscelli syndrome patients at the molecular level. Because Rab27B is widely expressed in various tissues together with Rab27A and has been found to have the ability to bind all of the Rab27A effectors that have been tested, Rab27A and Rab27B were initially thought to function redundantly by sharing common Rab27 effectors. However, recent evidence has indicated that by interacting with different Rab27 effectors Rab27A and Rab27B play different roles in special types of secretion (e.g. exosome secretion and mast cell secretion) even within the same cell type. In this review article, I describe the current state of our understanding of the functions of Rab27 effectors in secretory pathways.
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Affiliation(s)
- Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
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15
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Haefliger JA, Rohner-Jeanrenaud F, Caille D, Charollais A, Meda P, Allagnat F. Hyperglycemia downregulates Connexin36 in pancreatic islets via the upregulation of ICER-1/ICER-1γ. J Mol Endocrinol 2013; 51:49-58. [PMID: 23613279 DOI: 10.1530/jme-13-0054] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Channels formed by the gap junction protein Connexin36 (CX36) contribute to the proper control of insulin secretion. We previously demonstrated that chronic exposure to glucose decreases Cx36 levels in insulin-secreting cells in vitro. Here, we investigated whether hyperglycemia also regulates Cx36 in vivo. Using a model of continuous glucose infusion in adult rats, we showed that prolonged (24-48 h) hyperglycemia reduced the Cx36 gene Gjd2 mRNA levels in pancreatic islets. Accordingly, prolonged exposure to high glucose concentrations also reduced the expression and function of Cx36 in the rat insulin-producing INS-1E cell line. The glucose effect was blocked after inhibition of the cAMP/PKA pathway and was associated with an overexpression of the inducible cAMP early repressor ICER-1/ICER-1γ, which binds to a functional cAMP-response element in the promoter of the Cx36 gene Gjd2. The involvement of this repressor was further demonstrated using an antisense strategy of ICER-1 inhibition, which prevented glucose-induced downregulation of Cx36. The data indicate that chronic exposure to glucose alters the in vivo expression of Cx36 by the insulin-producing β-cells through ICER-1/ICER-1γ overexpression. This mechanism may contribute to the reduced glucose sensitivity and altered insulin secretion, which contribute to the pathophysiology of diabetes.
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Affiliation(s)
- Jacques-Antoine Haefliger
- Service of Internal Medicine, Department of Physiology, University Hospital Lausanne, Lausanne, Switzerland
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16
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Haefliger JA, Martin D, Favre D, Petremand Y, Mazzolai L, Abderrahmani A, Meda P, Waeber G, Allagnat F. Reduction of connexin36 content by ICER-1 contributes to insulin-secreting cells apoptosis induced by oxidized LDL particles. PLoS One 2013; 8:e55198. [PMID: 23383107 PMCID: PMC3559396 DOI: 10.1371/journal.pone.0055198] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 12/19/2012] [Indexed: 12/14/2022] Open
Abstract
Connexin36 (Cx36), a trans-membrane protein that forms gap junctions between insulin-secreting beta-cells in the Langerhans islets, contributes to the proper control of insulin secretion and beta-cell survival. Hypercholesterolemia and pro-atherogenic low density lipoproteins (LDL) contribute to beta-cell dysfunction and apoptosis in the context of Type 2 diabetes. We investigated the impact of LDL-cholesterol on Cx36 levels in beta-cells. As compared to WT mice, the Cx36 content was reduced in islets from hypercholesterolemic ApoE-/- mice. Prolonged exposure to human native (nLDL) or oxidized LDL (oxLDL) particles decreased the expression of Cx36 in insulin secreting cell-lines and isolated rodent islets. Cx36 down-regulation was associated with overexpression of the inducible cAMP early repressor (ICER-1) and the selective disruption of ICER-1 prevented the effects of oxLDL on Cx36 expression. Oil red O staining and Plin1 expression levels suggested that oxLDL were less stored as neutral lipid droplets than nLDL in INS-1E cells. The lipid beta-oxidation inhibitor etomoxir enhanced oxLDL-induced apoptosis whereas the ceramide synthesis inhibitor myriocin partially protected INS-1E cells, suggesting that oxLDL toxicity was due to impaired metabolism of the lipids. ICER-1 and Cx36 expressions were closely correlated with oxLDL toxicity. Cx36 knock-down in INS-1E cells or knock-out in primary islets sensitized beta-cells to oxLDL-induced apoptosis. In contrast, overexpression of Cx36 partially protected INS-1E cells against apoptosis. These data demonstrate that the reduction of Cx36 content in beta-cells by oxLDL particles is mediated by ICER-1 and contributes to oxLDL-induced beta-cell apoptosis.
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Affiliation(s)
| | - David Martin
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Dimitri Favre
- Department of Cellular Biology and Morphology, University of Lausanne, Lausanne, Switzerland
| | - Yannick Petremand
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Lucia Mazzolai
- Service of Vascular Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Amar Abderrahmani
- European Genomic Institute for Diabetes, UMR 8199, University of Lille Nord de France, Lille, France
| | - Paolo Meda
- Department of Cell Physiology and Metabolism, University Medical Center, Geneva, Switzerland
| | - Gérard Waeber
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Florent Allagnat
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
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17
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Brajkovic S, Marenzoni R, Favre D, Guérardel A, Salvi R, Beeler N, Froguel P, Vollenweider P, Waeber G, Abderrahmani A. Evidence for tuning adipocytes ICER levels for obesity care. Adipocyte 2012; 1:157-160. [PMID: 23700525 PMCID: PMC3609089 DOI: 10.4161/adip.20000] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Abnormal adipokine production, along with defective uptake and metabolism of glucose within adipocytes, contributes to insulin resistance and altered glucose homeostasis. Recent research has highlighted one of the mechanisms that accounts for impaired production of adiponectin (ADIPOQ) and adipocyte glucose uptake in obesity. In adipocytes of human obese subjects and mice fed with a high fat diet, the level of the inducible cAMP early repressor (ICER) is diminished. Reduction of ICER elevates the cAMP response element binding protein (CREB) activity, which in turn increases the repressor activating transcription factor 3. In fine, the cascade triggers reduction in the ADIPOQ and GLUT4 levels, which ultimately hampers insulin-mediated glucose uptake. The c-Jun N-terminal kinase (JNK) interacting-protein 1, also called islet brain 1 (IB1), is a target of CREB/ICER that promotes JNK-mediated insulin resistance in adipocytes. A rise in IB1 and c-Jun levels accompanies the drop of ICER in white adipose tissues of obese mice when compared with mice fed with a chow diet. Other than the expression of ADIPOQ and glucose transport, decline in ICER expression might impact insulin signaling. Impairment of ICER is a critical issue that will need major consideration in future therapeutic purposes.
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18
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Keller DM, Clark EA, Goodman RH. Regulation of microRNA-375 by cAMP in pancreatic β-cells. Mol Endocrinol 2012; 26:989-99. [PMID: 22539037 DOI: 10.1210/me.2011-1205] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
MicroRNA-375 (miR-375) is necessary for proper formation of pancreatic islets in vertebrates and is necessary for the development of β-cells in mice, but regulation of miR-375 in these cells is poorly understood. Here, we show that miR-375 is transcriptionally repressed by the cAMP-protein kinase A (PKA) pathway and that this repression is mediated through a block in RNA polymerase II binding to the miR-375 promoter. cAMP analogs that are PKA selective repress miR-375, as do cAMP agonists and the glucagon-like peptide-1 receptor agonist, exendin-4. Repression of the miR-375 precursor occurs rapidly in rat insulinoma INS-1 832/13 cells, within 15 min after cAMP stimulation, although the mature microRNA declines more slowly due to the kinetics of RNA processing. Repression of miR-375 in isolated rat islets by exendin-4 also occurs slowly, after several hours of stimulation. Glucose is another reported antagonist of miR-375 expression, although we demonstrate here that glucose does not target the microRNA through the PKA pathway. As reported previously, miR-375 negatively regulates insulin secretion, and attenuation of miR-375 through the cAMP-PKA pathway may boost the insulin response in pancreatic β-cells.
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Affiliation(s)
- David M Keller
- Department of Biological Sciences, California State University, Chico, CA 95929-0515, USA.
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19
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Cho IS, Jung M, Kwon KS, Moon E, Cho JH, Yoon KH, Kim JW, Lee YD, Kim SS, Suh-Kim H. Deregulation of CREB signaling pathway induced by chronic hyperglycemia downregulates NeuroD transcription. PLoS One 2012; 7:e34860. [PMID: 22509362 PMCID: PMC3318007 DOI: 10.1371/journal.pone.0034860] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 03/08/2012] [Indexed: 01/05/2023] Open
Abstract
CREB mediates the transcriptional effects of glucose and incretin hormones in insulin-target cells and insulin-producing β-cells. Although the inhibition of CREB activity is known to decrease the β-cell mass, it is still unknown what factors inversely alter the CREB signaling pathway in β-cells. Here, we show that β-cell dysfunctions occurring in chronic hyperglycemia are not caused by simple inhibition of CREB activity but rather by the persistent activation of CREB due to decreases in protein phophatase PP2A. When freshly isolated rat pancreatic islets were chronically exposed to 25 mM (high) glucose, the PP2A activity was reduced with a concomitant increase in active pCREB. Brief challenges with 15 mM glucose or 30 µM forskolin after 2 hour fasting further increased the level of pCREB and consequently induced the persistent expression of ICER. The excessively produced ICER was sufficient to repress the transcription of NeuroD, insulin, and SUR1 genes. In contrast, when islets were grown in 5 mM (low) glucose, CREB was transiently activated in response to glucose or forskolin stimuli. Thus, ICER expression was transient and insufficient to repress those target genes. Importantly, overexpression of PP2A reversed the adverse effects of chronic hyperglycemia and successfully restored the transient activation of CREB and ICER. Conversely, depletion of PP2A with siRNA was sufficient to disrupt the negative feedback regulation of CREB and induce hyperglycemic phenotypes even under low glucose conditions. Our findings suggest that the failure of the negative feedback regulation of CREB is the primary cause for β-cell dysfunctions under conditions of pathogenic hyperglycemia, and PP2A can be a novel target for future therapies aiming to protect β-cells mass in the late transitional phase of non-insulin dependent type 2 diabetes (NIDDM).
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Affiliation(s)
- In-Su Cho
- Department of Anatomy, Ajou University, Suwon, South Korea
- Graduate Neuroscience Program, Ajou University, Suwon, South Korea
- BK21, Division of Cell Transformation and Restoration, Ajou University, Suwon, South Korea
| | - Miyoung Jung
- Department of Biological Sciences, Ajou University, Suwon, South Korea
| | - Ki-Sun Kwon
- Aging Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
| | - Eunpyo Moon
- Department of Biological Sciences, Ajou University, Suwon, South Korea
| | - Jang-Hyeon Cho
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kun-Ho Yoon
- Department of Endocrinology, Catholic University, School of Medicine, Seoul, South Korea
| | - Ji-Won Kim
- Department of Endocrinology, Catholic University, School of Medicine, Seoul, South Korea
| | - Young-Don Lee
- Department of Anatomy, Ajou University, Suwon, South Korea
- Molecular Science and Technology, Ajou University, Suwon, South Korea
- Control for Cell Death Regulating Biodrug, Ajou University, Suwon, South Korea
| | - Sung-Soo Kim
- Department of Anatomy, Ajou University, Suwon, South Korea
- Control for Cell Death Regulating Biodrug, Ajou University, Suwon, South Korea
- * E-mail: (HS-K); (S-SK)
| | - Haeyoung Suh-Kim
- Department of Anatomy, Ajou University, Suwon, South Korea
- Graduate Neuroscience Program, Ajou University, Suwon, South Korea
- BK21, Division of Cell Transformation and Restoration, Ajou University, Suwon, South Korea
- * E-mail: (HS-K); (S-SK)
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20
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Schvartz D, Couté Y, Brunner Y, Wollheim CB, Sanchez JC. Modulation of neuronal pentraxin 1 expression in rat pancreatic β-cells submitted to chronic glucotoxic stress. Mol Cell Proteomics 2012; 11:244-54. [PMID: 22427704 DOI: 10.1074/mcp.m112.018051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Insulin secretory granules are β-cell vesicles dedicated to insulin processing, storage, and release. The secretion of insulin secretory granule content in response to an acute increase of glucose concentration is a highly regulated process allowing normal glycemic homeostasis. Type 2 diabetes is a metabolic disease characterized by chronic hyperglycemia. The consequent prolonged glucose exposure is known to exert deleterious effects on the function of various organs, notably impairment of insulin secretion by pancreatic β-cells and induction of apoptosis. It has also been described as modifying gene and protein expression in β-cells. Therefore, we hypothesized that a modulation of insulin secretory granule protein expression induced by chronic hyperglycemia may partially explain β-cell dysfunction. To identify the potential early molecular mechanisms underlying β-cell dysfunction during chronic hyperglycemia, we performed SILAC and mass spectrometry experiments to monitor changes in the insulin secretory granule proteome from INS-1E rat insulinoma β-cells cultivated either with 11 or 30 mm of glucose for 24 h. Fourteen proteins were found to be differentially expressed between these two conditions, and several of these proteins were not described before to be present in β-cells. Among them, neuronal pentraxin 1 was only described in neurons so far. Here we investigated its expression and intracellular localization in INS-1E cells. Furthermore, its overexpression in glucotoxic conditions was confirmed at the mRNA and protein levels. According to its role in hypoxia-ischemia-induced apoptosis described in neurons, this suggests that neuronal pentraxin 1 might be a new β-cell mediator in the AKT/GSK3 apoptotic pathway. In conclusion, the modification of specific β-cell pathways such as apoptosis and oxidative stress may partially explain the impairment of insulin secretion and β-cell failure, observed after prolonged exposure to high glucose concentrations.
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Affiliation(s)
- Domitille Schvartz
- Biomedical Proteomics Research Group, Department of Human Protein Sciences, University Medical Center, Geneva 1211, Switzerland
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21
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Bieganska K, Figiel I, Gierej D, Kaczmarek L, Klejman A. Silencing of ICERs (Inducible cAMP Early Repressors) results in partial protection of neurons from programmed cell death. Neurobiol Dis 2012; 45:701-10. [DOI: 10.1016/j.nbd.2011.10.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 09/21/2011] [Accepted: 10/16/2011] [Indexed: 11/30/2022] Open
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22
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Favre D, Le Gouill E, Fahmi D, Verdumo C, Chinetti-Gbaguidi G, Staels B, Caiazzo R, Pattou F, Lê KA, Tappy L, Regazzi R, Giusti V, Vollenweider P, Waeber G, Abderrahmani A. Impaired expression of the inducible cAMP early repressor accounts for sustained adipose CREB activity in obesity. Diabetes 2011; 60:3169-74. [PMID: 21998402 PMCID: PMC3219947 DOI: 10.2337/db10-1743] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 09/11/2011] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Increase in adipose cAMP-responsive element binding protein (CREB) activity promotes adipocyte dysfunction and systemic insulin resistance in obese mice. This is achieved by increasing the expression of activating transcription factor 3 (ATF3). In this study, we investigated whether impaired expression of the inducible cAMP early repressor (ICER), a transcriptional antagonist of CREB, is responsible for the increased CREB activity in adipocytes of obese mice and humans. RESEARCH DESIGN AND METHODS Total RNA and nuclear proteins were prepared from visceral adipose tissue (VAT) of human nonobese or obese subjects and white adipose tissue (WAT) of C57Bl6-Rj mice that were fed with normal or high-fat diet for 16 weeks. The expression of genes was monitored by real-time PCR, Western blotting, and electromobility shift assays. RNA interference was used to silence the expression of Icer. RESULTS The expression of Icer/ICER was reduced in VAT and WAT of obese humans and mice, respectively. Diminution of Icer/ICER was restricted to adipocytes and was accompanied by a rise of Atf3/ATF3 and diminution of Adipoq/ADIPOQ and Glut4/GLUT4. Silencing the expression of Icer in 3T3-L1 adipocytes mimicked the results observed in human and mice cells and hampered glucose uptake, thus confirming the requirement of Icer for appropriate adipocyte function. CONCLUSIONS Impaired expression of ICER contributes to elevation in CREB target genes and, therefore, to the development of insulin resistance in obesity.
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Affiliation(s)
- Dimitri Favre
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland
| | - Eric Le Gouill
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland
| | - Denis Fahmi
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland
| | - Chantal Verdumo
- Service of Endocrinology, Diabetology, and Metabolism, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Giulia Chinetti-Gbaguidi
- University of Lille Nord de France, INSERM UMR1011, UDSL, Institut Pasteur de Lille, Lille, France
| | - Bart Staels
- University of Lille Nord de France, INSERM UMR1011, UDSL, Institut Pasteur de Lille, Lille, France
| | - Robert Caiazzo
- Department of Endocrine Surgery, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille University, Lille, France
| | - François Pattou
- Department of Endocrine Surgery, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille University, Lille, France
| | - Kim-Anne Lê
- Childhood Obesity Research Center, Department of Preventive Medicine, University of Southern California, Los Angeles, California
| | - Luc Tappy
- Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Romano Regazzi
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland
| | - Vittorio Giusti
- Service of Endocrinology, Diabetology, and Metabolism, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Peter Vollenweider
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Gérard Waeber
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Amar Abderrahmani
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland
- University of Lille Nord de France, CNRS UMR-8199, European Genomic Institute for Diabetes, Lille, France
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23
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Favre D, Niederhauser G, Fahmi D, Plaisance V, Brajkovic S, Beeler N, Allagnat F, Haefliger JA, Regazzi R, Waeber G, Abderrahmani A. Role for inducible cAMP early repressor in promoting pancreatic beta cell dysfunction evoked by oxidative stress in human and rat islets. Diabetologia 2011; 54:2337-46. [PMID: 21547497 PMCID: PMC3149674 DOI: 10.1007/s00125-011-2165-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 04/01/2011] [Indexed: 02/03/2023]
Abstract
AIMS/HYPOTHESIS Pro-atherogenic and pro-oxidant, oxidised LDL trigger adverse effects on pancreatic beta cells, possibly contributing to diabetes progression. Because oxidised LDL diminish the expression of genes regulated by the inducible cAMP early repressor (ICER), we investigated the involvement of this transcription factor and of oxidative stress in beta cell failure elicited by oxidised LDL. METHODS Isolated human and rat islets, and insulin-secreting cells were cultured with human native or oxidised LDL or with hydrogen peroxide. The expression of genes was determined by quantitative real-time PCR and western blotting. Insulin secretion was monitored by EIA kit. Cell apoptosis was determined by scoring cells displaying pycnotic nuclei. RESULTS Exposure of beta cell lines and islets to oxidised LDL, but not to native LDL raised the abundance of ICER. Induction of this repressor by the modified LDL compromised the expression of important beta cell genes, including insulin and anti-apoptotic islet brain 1, as well as of genes coding for key components of the secretory machinery. This led to hampering of insulin production and secretion, and of cell survival. Silencing of this transcription factor by RNA interference restored the expression of its target genes and alleviated beta cell dysfunction and death triggered by oxidised LDL. Induction of ICER was stimulated by oxidative stress, whereas antioxidant treatment with N-acetylcysteine or HDL prevented the rise of ICER elicited by oxidised LDL and restored beta cell functions. CONCLUSIONS/INTERPRETATION Induction of ICER links oxidative stress to beta cell failure caused by oxidised LDL and can be effectively abrogated by antioxidant treatment.
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Affiliation(s)
- D. Favre
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - G. Niederhauser
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - D. Fahmi
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - V. Plaisance
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - S. Brajkovic
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - N. Beeler
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - F. Allagnat
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
| | - J. A. Haefliger
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
| | - R. Regazzi
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - G. Waeber
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
| | - A. Abderrahmani
- Service of Internal Medicine, CHUV-Hospital, Lausanne, Switzerland
- Department of Cell Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
- CNRS-UMR-8199, Université Lille Nord de France, UDSL, Lille, France
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Roger B, Papin J, Vacher P, Raoux M, Mulot A, Dubois M, Kerr-Conte J, Voy BH, Pattou F, Charpentier G, Jonas JC, Moustaïd-Moussa N, Lang J. Adenylyl cyclase 8 is central to glucagon-like peptide 1 signalling and effects of chronically elevated glucose in rat and human pancreatic beta cells. Diabetologia 2011; 54:390-402. [PMID: 21046358 DOI: 10.1007/s00125-010-1955-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 09/08/2010] [Indexed: 01/19/2023]
Abstract
AIMS/HYPOTHESIS Glucose and incretins regulate beta cell function, gene expression and insulin exocytosis via calcium and cAMP. Prolonged exposure to elevated glucose (also termed glucotoxicity) disturbs calcium homeostasis, but little is known about cAMP signalling. We therefore investigated long-term effects of glucose on this pathway with special regard to the incretin glucagon-like peptide 1 (GLP-1). METHODS We exposed INS-1E cells and rat or human islets to different levels of glucose for 3 days and determined functional responses in terms of second messengers (cAMP, Ca(2+)), transcription profiles, activation of cAMP-responsive element (CRE) and secretion by measuring membrane capacitance. Moreover, we modulated directly the abundance of a calcium-sensitive adenylyl cyclase (ADCY8) and GLP-1 receptor (GLP1R). RESULTS GLP-1- or forskolin-mediated increases in cytosolic calcium, cAMP-levels or insulin secretion were largely reduced in INS-1E cells cultured at elevated glucose (>5.5 mmol/l). Statistical analysis of transcription profiles identified cAMP pathways as major targets regulated by glucose. Quantitative PCR confirmed these findings and unravelled marked downregulation of the calcium-sensitive adenylyl cyclase ADCY8 also in rat and in human islets. Re-expression of ADCY8, but not of the GLP1R, recovered GLP-1 signalling in glucotoxicity in INS-1E cells and in rat islets. Moreover, knockdown of this adenylyl cyclase showed that GLP-1-induced cAMP generation, calcium signalling, activation of the downstream target CRE and direct amplification of exocytosis by cAMP-raising agents (evaluated by capacitance measurement) proceeds via ADCY8. CONCLUSIONS/INTERPRETATION cAMP-mediated pathways are modelled by glucose, and downregulation of the calcium-sensitive ADCY8 plays a central role herein, including signalling via the GLP1R.
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Affiliation(s)
- B Roger
- Université de Bordeaux 1, Institut Européen de Chimie et Biologie, UMR CNRS 5248, 2 Av Robert Escarpit, 33607 Pessac, France
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Kögel T, Gerdes HH. Roles of myosin Va and Rab3D in membrane remodeling of immature secretory granules. Cell Mol Neurobiol 2010; 30:1303-8. [PMID: 21080055 PMCID: PMC3008937 DOI: 10.1007/s10571-010-9597-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 09/02/2010] [Indexed: 01/24/2023]
Abstract
Neuroendocrine secretory granules (SGs) are formed at the trans-Golgi network (TGN) as immature intermediates. In PC12 cells, these immature SGs (ISGs) are transported within seconds to the cell cortex, where they move along actin filaments and complete maturation. This maturation process comprises acidification-dependent processing of cargo proteins, condensation of the SG matrix, and removal of membrane and proteins not destined to mature SGs (MSGs) into ISG-derived vesicles (IDVs). We investigated the roles of myosin Va and Rab3 isoforms in the maturation of ISGs in neuroendocrine PC12 cells. The expression of dominant-negative mutants of myosin Va or Rab3D blocked the removal of the endoprotease furin from ISGs. Furthermore, expression of mutant Rab3D, but not of mutant myosin Va, impaired cargo processing of SGs. In conclusion, our data suggest an implication of myosin Va and Rab3D in the maturation of SGs where they participate in overlapping but not identical tasks.
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Affiliation(s)
- Tanja Kögel
- Department of Biomedicine, University of Bergen, Jonas Lies Vei 91, 5009 Bergen, Norway
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26
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Piper Hanley K, Hearn T, Berry A, Carvell MJ, Patch AM, Williams LJ, Sugden SA, Wilson DI, Ellard S, Hanley NA. In vitro expression of NGN3 identifies RAB3B as the predominant Ras-associated GTP-binding protein 3 family member in human islets. J Endocrinol 2010; 207:151-61. [PMID: 20807725 PMCID: PMC2951179 DOI: 10.1677/joe-10-0120] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 08/05/2010] [Accepted: 08/31/2010] [Indexed: 12/17/2022]
Abstract
Neurogenin 3 (NGN3) commits pancreatic progenitors to an islet cell fate. We have induced NGN3 expression and identified upregulation of the gene encoding the Ras-associated small molecular mass GTP-binding protein, RAB3B. RAB3B localised to the cytoplasm of human β-cells, both during the foetal period and post natally. Genes encoding alternative RAB3 proteins and RAB27A were unaltered by NGN3 expression and in human adult islets their transcripts were many fold less prevalent than those of RAB3B. The regulation of insulin exocytosis in rodent β-cells and responsiveness to incretins are reliant on Rab family members, notably Rab3a and Rab27a, but not Rab3b. Our results support an important inter-species difference in regulating insulin exocytosis where RAB3B is the most expressed isoform in human islets.
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Affiliation(s)
| | - Tom Hearn
- Human Genetics DivisionUniversity of SouthamptonSouthampton, SO16 6YDUK
| | | | - Melanie J Carvell
- Beta-Cell Development and Function GroupKing's College LondonGuy's Campus, London, SE1 1ULUK
| | - Ann-Marie Patch
- Peninsula Medical SchoolInstitute of Biomedical and Clinical ScienceBarrack Road, Exeter, EX2 5DWUK
| | - Louise J Williams
- Human Genetics DivisionUniversity of SouthamptonSouthampton, SO16 6YDUK
| | | | - David I Wilson
- Human Genetics DivisionUniversity of SouthamptonSouthampton, SO16 6YDUK
| | - Sian Ellard
- Peninsula Medical SchoolInstitute of Biomedical and Clinical ScienceBarrack Road, Exeter, EX2 5DWUK
| | - Neil A Hanley
- (Correspondence should be addressed to N A Hanley; )
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Gaspar JM, Castilho Á, Baptista FI, Liberal J, Ambrósio AF. Long-term exposure to high glucose induces changes in the content and distribution of some exocytotic proteins in cultured hippocampal neurons. Neuroscience 2010; 171:981-92. [PMID: 20950673 DOI: 10.1016/j.neuroscience.2010.10.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 09/15/2010] [Accepted: 10/06/2010] [Indexed: 01/19/2023]
Abstract
A few studies have reported the existence of depletion of synaptic vesicles, and changes in neurotransmitter release and in the content of exocytotic proteins in the hippocampus of diabetic rats. Recently, we found that diabetes alters the levels of synaptic proteins in hippocampal nerve terminals. Hyperglycemia is considered the main trigger of diabetic complications, although other factors, such as low insulin levels, also contribute to diabetes-induced changes. Thus, the aim of this work was to evaluate whether long-term elevated glucose per se, which mimics prolonged hyperglycemia, induces significant changes in the content and localization of synaptic proteins involved in exocytosis in hippocampal neurons. Hippocampal cell cultures were cultured for 14 days and were exposed to high glucose (50 mM) or mannitol (osmotic control; 25 mM plus 25 mM glucose), for 7 days. Cell viability and nuclear morphology were evaluated by MTT and Hoechst assays, respectively. The protein levels of vesicle-associated membrane protein-2 (VAMP-2), synaptosomal-associated protein-25 (SNAP-25), syntaxin-1, synapsin-1, synaptophysin, synaptotagmin-1, rabphilin 3a, and also of vesicular glutamate and GABA transporters (VGluT-1 and VGAT), were evaluated by immunoblotting, and its localization was analyzed by immunocytochemistry. The majority of the proteins were not affected. However, elevated glucose decreased the content of SNAP-25 and increased the content of synaptotagmin-1 and VGluT-1. Moreover, there was an accumulation of syntaxin-1, synaptotagmin-1 and VGluT-1 in the cell body of some hippocampal neurons exposed to high glucose. No changes were detected in mannitol-treated cells. In conclusion, elevated glucose per se did not induce significant changes in the content of the majority of the synaptic proteins studied in hippocampal cultures, with the exception of SNAP-25, synaptotagmin-1 and VGluT-1. However, there was an accumulation of some proteins in cell bodies of hippocampal neurons exposed to elevated glucose, suggesting that the trafficking of these proteins to the synapse may be compromised. Moreover, these results also suggest that other factors, in addition to hyperglycemia, certainly contribute to alterations detected in synaptic proteins in diabetic animals.
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Affiliation(s)
- J M Gaspar
- Center of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, 3004-548 Coimbra, Portugal
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Béraud-Dufour S, Abderrahmani A, Noel J, Brau F, Waeber G, Mazella J, Coppola T. Neurotensin is a regulator of insulin secretion in pancreatic beta-cells. Int J Biochem Cell Biol 2010; 42:1681-8. [DOI: 10.1016/j.biocel.2010.06.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 06/18/2010] [Accepted: 06/23/2010] [Indexed: 11/29/2022]
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Yang AJ, Li CC, Lu CY, Liu KL, Tsai CW, Lii CK, Chen HW. Activation of the cAMP/CREB/inducible cAMP early repressor pathway suppresses andrographolide-induced gene expression of the pi class of glutathione S-transferase in rat primary hepatocytes. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:1993-2000. [PMID: 20063885 DOI: 10.1021/jf902221j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Andrographolide (Ap) is a bioactive compound in Andrographis paniculata that is a Chinese herb. The pi class of glutathione S-transferase (GSTP) is one kind of phase II detoxification enzyme. Here we show that induction of GSTP protein and mRNA expression in rat primary hepatocytes by Ap was inhibited by forskolin and a variety of cAMP analogues. The inhibitory effect of the cAMP analogues was partially blocked by pretreatment with H89. In the presence of Ap, forskolin, or both, the expression of phospho-cAMP response element-binding protein (CREB) was increased. Ap alone had no effect on inducible cAMP early repressor (ICER) mRNA expression; however, Ap played a potentiating role in forskolin-induced ICER mRNA expression. An EMSA and immunoprecipitation assay showed that ICER binding to cAMP-response element (CRE) was increased in cells cotreated with Ap and forskolin for 3 and 8 h. Taken together, these results suggest that ICER is likely to be involved in the suppression of Ap-induced GSTP expression caused by the increase of cAMP in rat primary hepatocytes.
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Affiliation(s)
- Ai-Jen Yang
- Department of Nutrition, Chung Shan Medical University, Taichung, Taiwan
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Cornu M, Modi H, Kawamori D, Kulkarni RN, Joffraud M, Thorens B. Glucagon-like peptide-1 increases beta-cell glucose competence and proliferation by translational induction of insulin-like growth factor-1 receptor expression. J Biol Chem 2010; 285:10538-45. [PMID: 20145256 DOI: 10.1074/jbc.m109.091116] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Glucagon-like peptide-1 (GLP-1) protects beta-cells against apoptosis, increases their glucose competence, and induces their proliferation. We previously demonstrated that the anti-apoptotic effect was mediated by an increase in insulin-like growth factor-1 receptor (IGF-1R) expression and signaling, which was dependent on autocrine secretion of insulin-like growth factor 2 (IGF-2). Here, we further investigated how GLP-1 induces IGF-1R expression and whether the IGF-2/IGF-1R autocrine loop is also involved in mediating GLP-1-increase in glucose competence and proliferation. We show that GLP-1 up-regulated IGF-1R expression by a protein kinase A-dependent translational control mechanism, whereas isobutylmethylxanthine, which led to higher intracellular accumulation of cAMP than GLP-1, increased both IGF-1R transcription and translation. We then demonstrated, using MIN6 cells and primary islets, that the glucose competence of these cells was dependent on the level of IGF-1R expression and on IGF-2 secretion. We showed that GLP-1-induced primary beta-cell proliferation was suppressed by Igf-1r gene inactivation and by IGF-2 immunoneutralization or knockdown. Together our data show that regulation of beta-cell number and function by GLP-1 depends on the cAMP/protein kinase A mediated-induction of IGF-1R expression and the increased activity of an IGF-2/IGF-1R autocrine loop.
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Affiliation(s)
- Marion Cornu
- Department of Physiology and Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland
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31
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Abstract
Glucose-stimulated insulin secretion from the islet beta-cell involves a sequence of metabolic events and an interplay between a wide range of signaling pathways leading to the generation of second messengers (e.g., cyclic nucleotides, adenine and guanine nucleotides, soluble lipid messengers) and mobilization of calcium ions. Consequent to the generation of necessary signals, the insulin-laden secretory granules are transported from distal sites to the plasma membrane for fusion and release of their cargo into the circulation. The secretory granule transport underlies precise changes in cytoskeletal architecture involving a well-coordinated cross-talk between various signaling proteins, including small molecular mass GTP-binding proteins (G proteins) and their respective effector proteins. The purpose of this article is to provide an overview of current understanding of the identity of small G proteins (e.g., Cdc42, Rac1, and ARF-6) and their corresponding regulatory factors (e.g., GDP/GTP-exchange factors, GDP-dissociation inhibitors) in the pancreatic beta-cell. Plausible mechanisms underlying regulation of these signaling proteins by insulin secretagogues are also discussed. In addition to their positive modulatory roles, certain small G proteins also contribute to the metabolic dysfunction and demise of the islet beta-cell seen in in vitro and in vivo models of impaired insulin secretion and diabetes. Emerging evidence also suggests significant insulin secretory abnormalities in small G protein knockout animals, further emphasizing vital roles for these proteins in normal health and function of the islet beta-cell. Potential significance of these experimental observations from multiple laboratories and possible avenues for future research in this area of islet research are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, 259 Mack Avenue, Detroit, MI 48202-3489, USA.
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Tsuboi T, Kitaguchi T, Karasawa S, Fukuda M, Miyawaki A. Age-dependent preferential dense-core vesicle exocytosis in neuroendocrine cells revealed by newly developed monomeric fluorescent timer protein. Mol Biol Cell 2010; 21:87-94. [PMID: 19889833 PMCID: PMC2801723 DOI: 10.1091/mbc.e09-08-0722] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 10/13/2009] [Accepted: 10/28/2009] [Indexed: 11/11/2022] Open
Abstract
Although it is evident that only a few secretory vesicles accumulating in neuroendocrine cells are qualified to fuse with the plasma membrane and release their contents to the extracellular space, the molecular mechanisms that regulate their exocytosis are poorly understood. For example, it has been controversial whether secretory vesicles are exocytosed randomly or preferentially according to their age. Using a newly developed protein-based fluorescent timer, monomeric Kusabira Green Orange (mK-GO), which changes color with a predictable time course, here we show that small GTPase Rab27A effectors regulate age-dependent exocytosis of secretory vesicles in PC12 cells. When the vesicles were labeled with mK-GO-tagged neuropeptide Y or tissue-type plasminogen activator, punctate structures with green or red fluorescence were observed. Application of high [K(+)] stimulation induced exocytosis of new (green) fluorescent secretory vesicles but not of old (red) vesicles. Overexpression or depletion of rabphilin and synaptotagmin-like protein4-a (Slp4-a), which regulate exocytosis positively and negatively, respectively, disturbed the age-dependent exocytosis of the secretory vesicles in different manners. Our results suggest that coordinate functions of the two effectors of Rab27A, rabphilin and Slp4-a, are required for regulated secretory pathway.
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Affiliation(s)
- Takashi Tsuboi
- *Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan
- Laboratory for Cell Function and Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
| | - Tetsuya Kitaguchi
- Life Function and Dynamics, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Wako, Saitama 351-0198, Japan
| | - Satoshi Karasawa
- Laboratory for Cell Function and Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
- Amalgaam Co., Ltd., Itabashi, Tokyo 173-0004, Japan; and
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Atsushi Miyawaki
- Laboratory for Cell Function and Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
- Life Function and Dynamics, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Wako, Saitama 351-0198, Japan
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Abstract
Technological developments make mass spectrometry (MS)-based proteomics a central pillar of biochemical research. MS has been very successful in cell culture systems, where sample amounts are not limiting. To extend its capabilities to extremely small, physiologically distinct cell types isolated from tissue, we developed a high sensitivity chromatographic system that measures nanogram protein mixtures for 8 h with very high resolution. This technology is based on splitting gradient effluents into a capture capillary and provides an inherent technical replicate. In a single analysis, this allowed us to characterize kidney glomeruli isolated by laser capture microdissection to a depth of more than 2,400 proteins. From pooled pancreatic islets of Langerhans, another type of "miniorgan," we obtained an in-depth proteome of 6,873 proteins, many of them involved in diabetes. We quantitatively compared the proteome of single islets, containing 2,000-4,000 cells, treated with high or low glucose levels, and covered most of the characteristic functions of beta cells. Our ultrasensitive analysis recapitulated known hyperglycemic changes but we also find components up-regulated such as the mitochondrial stress regulator Park7. Direct proteomic analysis of functionally distinct cellular structures opens up perspectives in physiology and pathology.
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Plaisance V, Perret V, Favre D, Abderrahmani A, Yang JY, Widmann C, Regazzi R. Role of the transcriptional factor C/EBPbeta in free fatty acid-elicited beta-cell failure. Mol Cell Endocrinol 2009; 305:47-55. [PMID: 19133313 DOI: 10.1016/j.mce.2008.12.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 12/04/2008] [Indexed: 01/09/2023]
Abstract
Fatty acids can favour the development of Type 2 diabetes by reducing insulin secretion and inducing apoptosis of pancreatic beta-cells. Here, we show that sustained exposure of the beta-cell line MIN6 or of isolated pancreatic islets to the most abundant circulating fatty acid palmitate increases the level of C/EBPbeta, an insulin transcriptional repressor. In contrast, two unsaturated fatty acids, oleate and linoleate were without effect. The induction of C/EBPbeta elicited by palmitate was prevented by inhibiting the ERK1/2 MAP kinase pathway or by reducing mitochondrial fatty acid oxidation with an inhibitor of Carnitine Palmitoyl Transferase-1. Overexpression of C/EBPbeta mimicked the detrimental effects of palmitate and resulted in a drastic reduction in insulin promoter activity, impairment in the capacity to respond to secretory stimuli and an increase in apoptosis. Our data suggest a potential involvement of C/EBPbeta as mediator of the deleterious effects of unsaturated free fatty acids on beta-cell function.
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Affiliation(s)
- Valérie Plaisance
- Department of Cell Biology and Morphology, Faculty of Biology and Medicine, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
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Shanmugam C, Katkoori VR, Jhala NC, Grizzle WE, Manne U. Immunohistochemical expression of rabphilin-3A-like (Noc2) in normal and tumor tissues of human endocrine pancreas. Biotech Histochem 2009; 84:39-45. [PMID: 19212825 DOI: 10.1080/10520290902738878] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Involvement of rabphilin-3A-like (RPH3AL), or Noc2, the potential effector of Ras-associated binding proteins Rab3A and Rab27A in the regulation of exocytotic processes in the endocrine pancreas has been demonstrated in experimental models. Noc2 expression together with other regulatory molecules of the exocytotic machinery in human tissues, however, has not been studied. We evaluated immunohistochemical expression of the key molecules of the exocytotic machinery, Noc2, Rab3A, Rab27A, and RIM2, together with the characteristic islet cell hormones, insulin and glucagon in normal and endocrine tumor tissues of human pancreas. Normal pancreatic islets were stained for all of these proteins and showed strong cytoplasmic localization. A similar pattern of strong cytoplasmic expression of these proteins was observed in the majority of endocrine tumors. By contrast, the exocrine portions of normal appearing pancreas completely lacked Rab27A staining and showed decreased expression of the proteins, Noc2, Rab3A, and RIM2. The staining pattern of Noc2 and Rab27A was similar to the staining pattern of glucagon-producing cells within the islets. The concomitant expression of Noc2 with these molecules suggests that Noc2 may serve as an effector for Rab3A and Rab27A and that it is involved in the regulation of exocytosis of the endocrine pancreas in humans.
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Affiliation(s)
- C Shanmugam
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294-7331, USA
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Higai K, Tsukada M, Moriya Y, Azuma Y, Matsumoto K. Prolonged high glucose suppresses phorbol 12-myristate 13-acetate and ionomycin-induced interleukin-2 mRNA expression in Jurkat cells. Biochim Biophys Acta Gen Subj 2008; 1790:8-15. [PMID: 18992303 DOI: 10.1016/j.bbagen.2008.10.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 09/29/2008] [Accepted: 10/03/2008] [Indexed: 01/13/2023]
Abstract
BACKGROUND The disturbance of immunological responses is a complication of diabetes mellitus. METHODS AND RESULTS We cultured Jurkat cells in 11.1 (normal) and 22.2 mmol/l (high) glucose for 12 weeks and stimulated them with 10 nmol/l phorbol 12-myristate 13-acetate (PMA) and 500 nmol/l ionomycin. RT-PCR revealed that induced interleukin (IL)-2 mRNA expression levels were suppressed in high glucose cultures compared to those in normal glucose. Promoter activities of IL-2, nuclear factor of activated T cells (NFAT), and activator protein-1 (AP-1), after 6 h stimulation with PMA and ionomycin, gradually decreased in high glucose cultures to approximately 20% of those in normal glucose at 12 weeks. The prolonged culture in high glucose increased inducible cAMP early repressor (ICER) II mRNA and protein levels, and overexpression of ICER II dose-dependently suppressed promoter activities of IL-2, NFAT, and AP-1. Moreover, ICER II mRNA expression was transiently induced by stimulation with PMA and ionomycin in normal glucose cultures; however, with high glucose, the induction disappeared. CONCLUSION These results indicate that ICER II protein accumulates during prolonged culture in high glucose and suppresses IL-2 mRNA expression in Jurkat cells.
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Affiliation(s)
- Koji Higai
- Department of Clinical Chemistry, School of Pharmaceutical Sciences, Toho University Miyama 2-2-1, Funabashi, Chiba 247-8510, Japan.
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Lovis P, Roggli E, Laybutt DR, Gattesco S, Yang JY, Widmann C, Abderrahmani A, Regazzi R. Alterations in microRNA expression contribute to fatty acid-induced pancreatic beta-cell dysfunction. Diabetes 2008; 57:2728-36. [PMID: 18633110 PMCID: PMC2551683 DOI: 10.2337/db07-1252] [Citation(s) in RCA: 265] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Visceral obesity and elevated plasma free fatty acids are predisposing factors for type 2 diabetes. Chronic exposure to these lipids is detrimental for pancreatic beta-cells, resulting in reduced insulin content, defective insulin secretion, and apoptosis. We investigated the involvement in this phenomenon of microRNAs (miRNAs), a class of noncoding RNAs regulating gene expression by sequence-specific inhibition of mRNA translation. RESEARCH DESIGN AND METHODS We analyzed miRNA expression in insulin-secreting cell lines or pancreatic islets exposed to palmitate for 3 days and in islets from diabetic db/db mice. We studied the signaling pathways triggering the changes in miRNA expression and determined the impact of the miRNAs affected by palmitate on insulin secretion and apoptosis. RESULTS Prolonged exposure of the beta-cell line MIN6B1 and pancreatic islets to palmitate causes a time- and dose-dependent increase of miR34a and miR146. Elevated levels of these miRNAs are also observed in islets of diabetic db/db mice. miR34a rise is linked to activation of p53 and results in sensitization to apoptosis and impaired nutrient-induced secretion. The latter effect is associated with inhibition of the expression of vesicle-associated membrane protein 2, a key player in beta-cell exocytosis. Higher miR146 levels do not affect the capacity to release insulin but contribute to increased apoptosis. Treatment with oligonucleotides that block miR34a or miR146 activity partially protects palmitate-treated cells from apoptosis but is insufficient to restore normal secretion. CONCLUSIONS Our findings suggest that at least part of the detrimental effects of palmitate on beta-cells is caused by alterations in the level of specific miRNAs.
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Affiliation(s)
- Pascal Lovis
- Department of Cell Biology and Morphology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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Abstract
The inducible cyclic AMP (cAMP) early repressor (ICER) and cAMP response element-binding protein (CREB) are transcriptional regulators of the cAMP-mediated signaling pathway. CREB has been demonstrated to be upregulated in the majority of childhood leukemias contributing to disease progression, whereas ICER, its endogenous repressor, was found to be downregulated. Our research focus has been the function of restored ICER expression. ICER exogenously expressed in cell lines decreases CREB protein level and induces a lowered clonogenic potential in vitro. It decreases the ability of HL60 to invade the extramedullary sites and to promote bone marrow angiogenesis in nonobese diabetic-severe combined immunodeficient mice, demonstrating its potential effects on tumor progression. ICER represses the majority of 96 target genes upregulated by CREB. It binds CRE promoters and controls gene expression restoring the normal regulation of major cellular pathways. ICER is subjected to degradation through a constitutively active form of the extracellular signal-regulated protein kinase, which drives it to the proteasome. We propose that ICER is downregulated in HL60 to preserve CREB overexpression, which disrupts normal myelopoiesis and promotes blast proliferation. These findings define the function of ICER as a tumor suppressor in leukemia. Unbalanced CREB/ICER expression needs to be considered a pathogenetic feature in leukemogenesis. The molecular characterization of this pathway could be useful for novel therapeutic strategies.
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Martin D, Allagnat F, Chaffard G, Caille D, Fukuda M, Regazzi R, Abderrahmani A, Waeber G, Meda P, Maechler P, Haefliger JA. Functional significance of repressor element 1 silencing transcription factor (REST) target genes in pancreatic beta cells. Diabetologia 2008; 51:1429-39. [PMID: 18385973 DOI: 10.1007/s00125-008-0984-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Accepted: 02/19/2008] [Indexed: 11/30/2022]
Abstract
AIMS/HYPOTHESIS The expression of several neuronal genes in pancreatic beta cells is due to the absence of the transcription factor repressor element 1 (RE-1) silencing transcription factor (REST). The identification of these traits and their functional significance in beta cells has only been partly elucidated. Herein, we investigated the biological consequences of a repression of REST target genes by expressing REST in beta cells. METHODS The effect of REST expression on glucose homeostasis, insulin content and release, and beta cell mass was analysed in transgenic mice selectively expressing REST in beta cells. Relevant target genes were identified in INS-1E and primary beta cells expressing REST. RESULTS Transgenic mice featuring a beta cell-targeted expression of REST exhibited glucose intolerance and reduced beta cell mass. In primary beta cells, REST repressed several proteins of the exocytotic machinery, including synaptosomal-associated protein (SNAP) 25, synaptotagmin (SYT) IV, SYT VII, SYT IX and complexin II; it impaired first and second phases of insulin secretion. Using RNA interference in INS-1E cells, we showed that SYT IV and SYT VII were implicated in the control of insulin release. CONCLUSIONS/INTERPRETATION The data document the critical role of REST target genes in pancreatic beta cells. Specifically, we provide evidence that the downregulation of these genes is detrimental for the exocytosis of large dense core vesicles, thus contributing to beta cell dysfunction and impaired glucose homeostasis.
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Affiliation(s)
- D Martin
- Department of Medicine, University Hospital, CHUV, Lausanne, Switzerland
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40
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Corbeel L, Freson K. Rab proteins and Rab-associated proteins: major actors in the mechanism of protein-trafficking disorders. Eur J Pediatr 2008; 167:723-9. [PMID: 18463892 PMCID: PMC2413085 DOI: 10.1007/s00431-008-0740-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Accepted: 04/08/2008] [Indexed: 11/28/2022]
Abstract
UNLABELLED Ras-associated binding (Rab) proteins and Rab-associated proteins are key regulators of vesicle transport, which is essential for the delivery of proteins to specific intracellular locations. More than 60 human Rab proteins have been identified, and their function has been shown to depend on their interaction with different Rab-associated proteins regulating Rab activation, post-translational modification and intracellular localization. The number of known inherited disorders of vesicle trafficking due to Rab cycle defects has increased substantially during the past decade. This review describes the important role played by Rab proteins in a number of rare monogenic diseases as well as common multifactorial human ones. Although the clinical phenotype in these monogenic inherited diseases is highly variable and dependent on the type of tissue in which the defective Rab or its associated protein is expressed, frequent features are hypopigmentation (Griscelli syndrome), eye defects (Choroideremia, Warburg Micro syndrome and Martsolf syndrome), disturbed immune function (Griscelli syndrome and Charcot-Marie-Tooth disease) and neurological dysfunction (X-linked non-specific mental retardation, Charcot-Marie-Tooth disease, Warburg Micro syndrome and Martsolf syndrome). There is also evidence that alterations in Rab function play an important role in the progression of multifactorial human diseases, such as infectious diseases and type 2 diabetes. Rab proteins must not only be bound to GTP, but they need also to be 'prenylated'-i.e. bound to the cell membranes by isoprenes, which are intermediaries in the synthesis of cholesterol (e.g. geranyl geranyl or farnesyl compounds). This means that isoprenylation can be influenced by drugs such as statins, which inhibit isoprenylation, or biphosphonates, which inhibit that farnesyl pyrophosphate synthase necessary for Rab GTPase activity. CONCLUSION Although protein-trafficking disorders are clinically heterogeneous and represented in almost every subspeciality of pediatrics, the identification of common pathogenic mechanisms may provide a better diagnosis and management of patients with still unknown Rab cycle defects and stimulate the development of therapeutic agents.
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Affiliation(s)
- Lucien Corbeel
- Department of Pediatrics, University Hospital, Herestraat 49, 3000 Leuven, Belgium.
| | - Kathleen Freson
- Center for Molecular and Vascular Biology, University of Leuven, Leuven, Belgium
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Ferdaoussi M, Abdelli S, Yang JY, Cornu M, Niederhauser G, Favre D, Widmann C, Regazzi R, Thorens B, Waeber G, Abderrahmani A. Exendin-4 protects beta-cells from interleukin-1 beta-induced apoptosis by interfering with the c-Jun NH2-terminal kinase pathway. Diabetes 2008; 57:1205-15. [PMID: 18252896 DOI: 10.2337/db07-1214] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE The pro-inflammatory cytokine interleukin-1 beta (IL-1 beta) generates pancreatic beta-cells apoptosis mainly through activation of the c-Jun NH(2)-terminal kinase (JNK) pathway. This study was designed to investigate whether the long-acting agonist of the hormone glucagon-like peptide 1 (GLP-1) receptor exendin-4 (ex-4), which mediates protective effects against cytokine-induced beta-cell apoptosis, could interfere with the JNK pathway. RESEARCH DESIGN AND METHODS Isolated human, rat, and mouse islets and the rat insulin-secreting INS-1E cells were incubated with ex-4 in the presence or absence of IL-1 beta. JNK activity was assessed by solid-phase JNK kinase assay and quantification of c-Jun expression. Cell apoptosis was determined by scoring cells displaying pycnotic nuclei. RESULTS Ex-4 inhibited induction of the JNK pathway elicited by IL-1 beta. This effect was mimicked with the use of cAMP-raising agents isobutylmethylxanthine and forskolin and required activation of the protein kinase A. Inhibition of the JNK pathway by ex-4 or IBMX and forskolin was concomitant with a rise in the levels of islet-brain 1 (IB1), a potent blocker of the stress-induced JNK pathway. In fact, ex-4 as well as IBMX and forskolin induced expression of IB1 at the promoter level through cAMP response element binding transcription factor 1. Suppression of IB1 levels with the use of RNA interference strategy impaired the protective effects of ex-4 against apoptosis induced by IL-1 beta. CONCLUSIONS The data establish the requirement of IB1 in the protective action of ex-4 against apoptosis elicited by IL-1 beta and highlight the GLP-1 mimetics as new potent inhibitors of the JNK signaling induced by cytokines.
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Affiliation(s)
- Mourad Ferdaoussi
- Service of Internal Medicine, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Lausanne, Switzerland
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Lu H, Yang Y, Allister EM, Wijesekara N, Wheeler MB. The identification of potential factors associated with the development of type 2 diabetes: a quantitative proteomics approach. Mol Cell Proteomics 2008; 7:1434-51. [PMID: 18448419 DOI: 10.1074/mcp.m700478-mcp200] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type 2 diabetes (T2D) arises when pancreatic beta-cells fail to compensate for systemic insulin resistance with appropriate insulin secretion. However, the link between insulin resistance and beta-cell failure in T2D is not fully understood. To explore this association, we studied transgenic MKR mice that initially develop insulin resistance in skeletal muscle but by 8 weeks of age have T2D. In the present study, global islet protein and gene expression changes were characterized in diabetic MKR versus non-diabetic control mice at 10 weeks of age. Using a quantitative proteomics approach (isobaric tags for relative and absolute quantification (iTRAQ)), 159 proteins were differentially expressed in MKR compared with control islets. Marked up-regulation of protein biosynthesis and endoplasmic reticulum stress pathways and parallel down-regulation in insulin processing/secretion, energy utilization, and metabolism were observed. A fraction of the differentially expressed proteins identified (including GLUT2, DNAJC3, VAMP2, RAB3A, and PC1/3) were linked previously to insulin-secretory defects and T2D. However, many proteins for the first time were associated with islet dysfunction, including the unfolded protein response proteins (ERP72, ERP44, ERP29, PPIB, FKBP2, FKBP11, and DNAJB11), endoplasmic reticulum-associated degradation proteins (VCP and UFM1), and multiple proteins associated with mitochondrial energy metabolism (NDUFA9, UQCRH, COX2, COX4I1, COX5A, ATP6V1B2, ATP6V1H, ANT1, ANT2, ETFA, and ETFB). The mRNA expression level corresponding to these proteins was examined by microarray, and then a small subset was validated using quantitative real time PCR and Western blot analyses. Importantly approximately 54% of differentially expressed proteins in MKR islets (including proteins involved in proinsulin processing, protein biosynthesis, and mitochondrial oxidation) showed changes in the proteome but not transcriptome, suggesting post-transcriptional regulation. These results underscore the importance of integrated mRNA and protein expression measurements and validate the use of the iTRAQ method combined with microarray to assess global protein and gene changes involved in the development of T2D.
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Affiliation(s)
- Hongfang Lu
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto M5S 1A8, Canada
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Lovis P, Gattesco S, Regazzi R. Regulation of the expression of components of the exocytotic machinery of insulin-secreting cells by microRNAs. Biol Chem 2008; 389:305-12. [DOI: 10.1515/bc.2008.026] [Citation(s) in RCA: 214] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Abstract
Fine-tuning of insulin secretion from pancreatic β-cells participates in blood glucose homeostasis. Defects in this process can lead to chronic hyperglycemia and diabetes mellitus. Several proteins controlling insulin exocytosis have been identified, but the mechanisms regulating their expression remain poorly understood. Here, we show that two non-coding microRNAs, miR124a and miR96, modulate the expression of proteins involved in insulin exocytosis and affect secretion of the β-cell line MIN6B1. miR124a increases the levels of SNAP25, Rab3A and synapsin-1A and decreases those of Rab27A and Noc2. Inhibition of Rab27A expression is mediated by direct binding to the 3′-untranslated region of Rab27A mRNA. The effect on the other genes is indirect and linked to changes in mRNA levels. Over-expression of miR124a leads to exaggerated hormone release under basal conditions and a reduction in glucose-induced secretion. miR96 increases mRNA and protein levels of granuphilin, a negative modulator of insulin exocytosis, and decreases the expression of Noc2, resulting in lower capacity of MIN6B1 cells to respond to secretagogues. Our data identify miR124a and miR96 as novel regulators of the expression of proteins playing a critical role in insulin exocytosis and in the release of other hormones and neurotransmitters.
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Allagnat F, Alonso F, Martin D, Abderrahmani A, Waeber G, Haefliger JA. ICER-1gamma overexpression drives palmitate-mediated connexin36 down-regulation in insulin-secreting cells. J Biol Chem 2008; 283:5226-34. [PMID: 18073214 DOI: 10.1074/jbc.m708181200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Channels formed by the gap junction protein connexin36 (Cx36) contribute to the proper control of insulin secretion. We investigated the impact of chronic hyperlipidemia on Cx36 expression in pancreatic beta-cells. Prolonged exposure to the saturated free fatty acid palmitate reduced the expression of Cx36 in several insulin-secreting cell lines and isolated mouse islets. The effect of palmitate was fully blocked upon protein kinase A (PKA) inhibition by H89 and (Rp)-cAMP, indicating that the cAMP/PKA pathway is involved in the control of Cx36 expression. Palmitate treatment led to overexpression of the inducible cAMP early repressor (ICER-1gamma), which bound to a functional cAMP-response element located in the promoter of the CX36 gene. Inhibition of ICER-1gamma overexpression prevented the Cx36 decrease, as well as the palmitate-induced beta-cell secretory dysfunction. Finally, freshly isolated islets from mice undergoing a long term high fat diet expressed reduced Cx36 levels and increased ICER-1gamma levels. Taken together, these data demonstrate that chronic exposure to palmitate inhibits the Cx36 expression through PKA-mediated ICER-1gamma overexpression. This Cx36 down-regulation may contribute to the reduced glucose sensitivity and altered insulin secretion observed during the pre-diabetic stage and in the metabolic syndrome.
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Affiliation(s)
- Florent Allagnat
- Department of Medicine, University Hospital, CHUV-1011 Lausanne, Switzerland
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45
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Katkoori VR, Jia X, Chatla C, Kumar S, Ponnazhagan S, Callens T, Messiaen L, Grizzle WE, Manne U. Clinical significance of a novel single nucleotide polymorphism in the 5' untranslated region of the Rabphillin-3A-Like gene in colorectal adenocarcinoma. FRONT BIOSCI-LANDMRK 2008; 13:1050-61. [PMID: 17981610 DOI: 10.2741/2742] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The recently identified human ortholog of the Rabphillin-3A-Like (RPH3AL) gene, located at the 17p13.3 locus, has been assessed for its mutational status and clinical significance in colorectal adenocarcinoma (CRC). Prospectively collected 95 frozen CRCs and their matching benign colonic epithelial tissues were evaluated for mutations and mRNA expression. Since, we observed a higher incidence of a single nucleotide polymorphism (SNP) at the -25 position in the 5'untranslated region (5'UTR-25) of RPH3AL, we performed the genotyping analysis of this SNP in a retrospective CRC cohort (n=134) to assess their clinical importance. Univariate and multivariate outcome analyses were performed. The cDNA analysis has detected point mutations in 6 CRCs, coding region SNPs in 14 CRCs, and non-coding region SNPs in 38 CRCs. Combined analyses of both cohorts has demonstrated that the incidence of SNP at 5'UTR-25 was 41% (95 of 229), and its A/A genotype (9%, 20 of 229) was observed exclusively in non-Hispanic Caucasians, and 19 of these cases were diagnosed with nodal metastasis. Patients who exhibited homozygous for A or C alleles had a significantly decreased levels of mRNA expression, increased risk of CRC recurrence and mortality. Therefore, these findings have significant clinical implications in assessing the aggressiveness of CRC.
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Affiliation(s)
- Venkat R Katkoori
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294-7331, USA
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Bibliography. Current world literature. Diabetes and the endocrine pancreas II. Curr Opin Endocrinol Diabetes Obes 2007; 14:329-57. [PMID: 17940461 DOI: 10.1097/med.0b013e3282c3a898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
PURPOSE OF THE REVIEW In addition to its metabolic function, glucose modulates gene expression which is crucial in adapting cells to variations in glycaemia. We summarize recent advances in our understanding of regulation of gene expression by glucose. RECENT FINDINGS In-vivo and in-vitro experiments demonstrated that glucose regulates the transcription of genes encoding not only lipogenic and glycolytic enzymes but also proteins involved in global cell functions. The molecular mechanisms have begun to be elucidated, and the transcription factor carbohydrate responsive element-binding protein has emerged as a key actor, at least in liver. More recently, other candidates have been proposed, such as liver X receptors. In pathological situations, altered glycaemic control, as observed in diabetes mellitus, is associated with increased risk for microvascular and macrovascular complications. Recent findings suggest that changes in gene expression occurring in response to hyperglycaemia represent a novel component of glucotoxicity. SUMMARY Until recently, the direct transcriptional effects of glucose were underestimated, and insulin was considered to be the major regulator of gene expression in response to glycaemic variation. The recent discovery and characterization of transcription factors mediating the glucose response demonstrate that glucose, like fatty acids and other key nutrients, can directly control gene expression.
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48
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Abderrahmani A, Niederhauser G, Favre D, Abdelli S, Ferdaoussi M, Yang JY, Regazzi R, Widmann C, Waeber G. Human high-density lipoprotein particles prevent activation of the JNK pathway induced by human oxidised low-density lipoprotein particles in pancreatic beta cells. Diabetologia 2007; 50:1304-14. [PMID: 17437081 DOI: 10.1007/s00125-007-0642-z] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 01/15/2007] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS We explored the potential adverse effects of pro-atherogenic oxidised LDL-cholesterol particles on beta cell function. MATERIALS AND METHODS Isolated human and rat islets and different insulin-secreting cell lines were incubated with human oxidised LDL with or without HDL particles. The insulin level was monitored by ELISA, real-time PCR and a rat insulin promoter construct linked to luciferase gene reporter. Cell apoptosis was determined by scoring cells displaying pycnotic nuclei. RESULTS Prolonged incubation with human oxidised LDL particles led to a reduction in preproinsulin expression levels, whereas the insulin level was preserved in the presence of native LDL-cholesterol. The loss of insulin production occurred at the transcriptional levels and was associated with an increase in activator protein-1 transcriptional activity. The rise in activator protein-1 activity resulted from activation of c-Jun N-terminal kinases (JNK, now known as mitogen-activated protein kinase 8 [MAPK8]) due to a subsequent decrease in islet-brain 1 (IB1; now known as MAPK8 interacting protein 1) levels. Consistent with the pro-apoptotic role of the JNK pathway, oxidised LDL also induced a twofold increase in the rate of beta cell apoptosis. Treatment of the cells with JNK inhibitor peptides or HDL countered the effects mediated by oxidised LDL. CONCLUSIONS/INTERPRETATION These data provide strong evidence that oxidised LDL particles exert deleterious effects in the progression of beta cell failure in diabetes and that these effects can be countered by HDL particles.
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Affiliation(s)
- A Abderrahmani
- Service of Internal Medicine, CHUV-Hospital, Rue du Bugnon 9, 1005 Lausanne, Switzerland.
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49
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MacDonald PE, Rorsman P. The Ins and Outs of Secretion from Pancreatic β-Cells: Control of Single-Vesicle Exo- and Endocytosis. Physiology (Bethesda) 2007; 22:113-21. [PMID: 17420302 DOI: 10.1152/physiol.00047.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exocytosis of insulin-containing secretory vesicles in pancreatic β-cells is crucial to maintenance of plasma glucose levels. They fuse with the plasma membrane in a regulated manner to release their contents and are subsequently recaptured either intact or through conventional clathrin-mediated endocytosis. Here, we discuss these mechanisms in β-cells at the single-vesicle level.
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Affiliation(s)
- Patrick E MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada.
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Morales V, Gonzalez-Robayna I, Santana MP, Hernandez I, Fanjul LF. Tumor necrosis factor-alpha activates transcription of inducible repressor form of 3',5'-cyclic adenosine 5'-monophosphate-responsive element binding modulator and represses P450 aromatase and inhibin alpha-subunit expression in rat ovarian granulosa cells by a p44/42 mitogen-activated protein kinase-dependent mechanism. Endocrinology 2006; 147:5932-9. [PMID: 16946004 DOI: 10.1210/en.2006-0635] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The proinflammatory cytokine TNFalpha has important actions at the level of the ovary, including inhibition of P450 aromatase (P450AROM) activity and the secretion of inhibin, two proteins that are markers of the granulosa cell's differentiated status. Because the transcription of both P450AROM and inhibin alpha-subunit can be suppressed in the ovary by the inducible repressor isoform of cAMP-responsive element binding modulator (ICER), we have investigated whether TNFalpha and its intracellular messenger ceramide can induce ICER expression and the mechanisms whereby the induction is accomplished. ICER mRNA levels were assessed by RT-PCR in granulosa cells treated with TNFalpha, the ceramide-mobilizing enzyme sphingomyelinase (SMase), or C6-cer, a cell-permeant ceramide analog. Rapid (3 h) yet transient increases in the four isoforms of ICER were observed in response to all treatments. Likewise, ICER protein measured by immunoprecipitation with a specific antibody increases after TNFalpha, SMase, or C6-cer treatment. The mandatory phosphorylation of cAMP-responsive element binding was also observed in response to TNFalpha, SMase, or C6-cer and shown to be prevented by the p44/42 MAPK-specific inhibitor PD098059 but no other kinase blockers. Activation of p44/42 MAPK by the cytokine and its messenger was subsequently demonstrated as well as the inhibition of ICER expression by PD098059. Finally, the blocking of p44/42 MAPK activation prevented TNFalpha inhibition of FSH-dependent increases in P450AROM and inhibin alpha-subunit mRNA levels, thus indicating that p44/42 MAPK-mediated ICER expression may be accountable for the effects of TNFalpha on the expression of both proteins.
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Affiliation(s)
- Victoria Morales
- Department of Biochemistry and Physiology, Facultad de Medicina, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, 35016, Spain
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