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Mueller JW, Thomas P, Dalgaard LT, da Silva Xavier G. Sulfation pathways in the maintenance of functional beta-cell mass and implications for diabetes. Essays Biochem 2024; 68:509-522. [PMID: 39290144 PMCID: PMC11625869 DOI: 10.1042/ebc20240034] [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: 07/04/2024] [Revised: 08/21/2024] [Accepted: 09/02/2024] [Indexed: 09/19/2024]
Abstract
Diabetes Type 1 and Type 2 are widely occurring diseases. In spite of a vast amount of biomedical literature about diabetic processes in general, links to certain biological processes are only becoming evident these days. One such area of biology is the sulfation of small molecules, such as steroid hormones or metabolites from the gastrointestinal tract, as well as larger biomolecules, such as proteins and proteoglycans. Thus, modulating the physicochemical propensities of the different sulfate acceptors, resulting in enhanced solubility, expedited circulatory transit, or enhanced macromolecular interaction. This review lists evidence for the involvement of sulfation pathways in the maintenance of functional pancreatic beta-cell mass and the implications for diabetes, grouped into various classes of sulfated biomolecule. Complex heparan sulfates might play a role in the development and maintenance of beta-cells. The sulfolipids sulfatide and sulfo-cholesterol might contribute to beta-cell health. In beta-cells, there are only very few proteins with confirmed sulfation on some tyrosine residues, with the IRS4 molecule being one of them. Sulfated steroid hormones, such as estradiol-sulfate and vitamin-D-sulfate, may facilitate downstream steroid signaling in beta-cells, following de-sulfation. Indoxyl sulfate is a metabolite from the intestine, that causes kidney damage, contributing to diabetic kidney disease. Finally, from a technological perspective, there is heparan sulfate, heparin, and chondroitin sulfate, that all might be involved in next-generation beta-cell transplantation. Sulfation pathways may play a role in pancreatic beta-cells through multiple mechanisms. A more coherent understanding of sulfation pathways in diabetes will facilitate discussion and guide future research.
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Affiliation(s)
- Jonathan Wolf Mueller
- Department of Metabolism and Systems Science, University of Birmingham, Birmingham, U.K
| | - Patricia Thomas
- Department of Metabolism and Systems Science, University of Birmingham, Birmingham, U.K
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2
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Zhou W, Zhao X, Hassan A, Jia B, Liu L, Huang Q. Uncovering the function of insulin receptor substrate in termites' immunity through active immunization. JOURNAL OF INSECT SCIENCE (ONLINE) 2024; 24:1. [PMID: 38958928 PMCID: PMC11221318 DOI: 10.1093/jisesa/ieae061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 04/03/2024] [Accepted: 06/28/2024] [Indexed: 07/04/2024]
Abstract
Insulin receptor substrate (IRS) proteins are key mediators in insulin signaling pathway. In social insect lives, IRS proteins played important roles in caste differentiation and foraging, but there function in disease defenses such as active immunization has not been reported yet. To investigate the issue, we successfully suppressed the IRS gene 3 days after dsRNA injection. Suppressing IRS gene increased the contents of glucose, trehalose, glycogen, and triglyceride and decreased the content of pyruvate in termites, and led to the metabolic disorder of glucose and lipids. IRS suppressing significantly enhanced grooming behaviors of nestmates of fungus-contaminated termites and hence increased the conidial load in the guts of the nestmates. Additionally, IRS suppressing led to significant downregulation of the immune genes Gram-negative bacteria-binding protein2 (GNBP2) and termicin and upregulation of the apoptotic gene caspase8, and hence diminished antifungal activity of nestmates of fungus-contaminated termites. The above abnormal behavioral and physiological responses significantly decreased the survival rate of dsIRS-injected nestmates of the fungus-contaminated termites. These findings suggest that IRS is involved in regulation of active immunization in termites, providing a better understanding of the link between insulin signaling and the social immunity of termites.
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Affiliation(s)
- Wei Zhou
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Xingying Zhao
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Ali Hassan
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, Huazhong Agricultural University, Wuhan 430070, China
| | - Bao Jia
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- Nanning Institute of Termite Control, Nanning 530023, China
| | - Long Liu
- Henan International Laboratory for Green Pest Control, Henan Engineering Laboratory of Pest Biological Control, College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Qiuying Huang
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, Huazhong Agricultural University, Wuhan 430070, China
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3
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Guijarro LG, Justo Bermejo FJ, Boaru DL, De Castro-Martinez P, De Leon-Oliva D, Fraile-Martínez O, Garcia-Montero C, Alvarez-Mon M, Toledo-Lobo MDV, Ortega MA. Is Insulin Receptor Substrate4 (IRS4) a Platform Involved in the Activation of Several Oncogenes? Cancers (Basel) 2023; 15:4651. [PMID: 37760618 PMCID: PMC10526421 DOI: 10.3390/cancers15184651] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 09/06/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023] Open
Abstract
The IRS (insulin receptor substrate) family of scaffold proteins includes insulin receptor substrate-4 (IRS4), which is expressed only in a few cell lines, including human kidney, brain, liver, and thymus and some cell lines. Its N-terminus carries a phosphotyrosine-binding (PTB) domain and a pleckstrin homology domain (PH), which distinguishes it as a member of this family. In this paper, we collected data about the molecular mechanisms that explain the relevance of IRS4 in the development of cancer and identify IRS4 differences that distinguish it from IRS1 and IRS2. Search engines and different databases, such as PubMed, UniProt, ENSEMBL and SCANSITE 4.0, were used. We used the name of the protein that it encodes "(IRS-4 or IRS4)", or the combination of these terms with the word "(cancer)" or "(human)", for searches. Terms related to specific tumor pathologies ("breast", "ovary", "colon", "lung", "lymphoma", etc.) were also used. Despite the lack of knowledge on IRS4, it has been reported that some cancers and benign tumors are characterized by high levels of IRS-4 expression. Specifically, the role of IRS-4 in different types of digestive tract neoplasms, gynecological tumors, lung cancers, melanomas, hematological tumors, and other less common types of cancers has been shown. IRS4 differs from IRS1 and IRS2 in that can activate several oncogenes that regulate the PI3K/Akt cascade, such as BRK and FER, which are characterized by tyrosine kinase-like activity without regulation via extracellular ligands. In addition, IRS4 can activate the CRKL oncogene, which is an adapter protein that regulates the MAP kinase cascade. Knowledge of the role played by IRS4 in cancers at the molecular level, specifically as a platform for oncogenes, may enable the identification and validation of new therapeutic targets.
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Affiliation(s)
- Luis G. Guijarro
- Unit of Biochemistry and Molecular Biology, Department of System Biology (CIBEREHD), University of Alcalá, 28801 Alcala de Henares, Spain
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
| | | | - Diego Liviu Boaru
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain;
| | - Patricia De Castro-Martinez
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain;
| | - Diego De Leon-Oliva
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain;
| | - Oscar Fraile-Martínez
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain;
| | - Cielo Garcia-Montero
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain;
| | - Melchor Alvarez-Mon
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain;
- Immune System Diseases-Rheumatology, Oncology Service and Internal Medicine (CIBEREHD), University Hospital Príncipe de Asturias, 28806 Alcala de Henares, Spain
| | - María del Val Toledo-Lobo
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
- Department of Biomedicine and Biotechnology, University of Alcalá, 28801 Alcala de Henares, Spain;
| | - Miguel A. Ortega
- Ramón y Cajal Institute of Sanitary Research (IRYCIS), 28034 Madrid, Spain; (D.L.B.); (D.D.L.-O.); (O.F.-M.); (C.G.-M.); (M.A.-M.); (M.A.O.)
- Department of Medicine and Medical Specialities, Faculty of Medicine and Health Sciences, University of Alcalá, 28801 Alcala de Henares, Spain;
- Cancer Registry and Pathology Department, Principe de Asturias University Hospital, 28806 Alcala de Henares, Spain
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Newsholme P, Rowlands J, Rose’Meyer R, Cruzat V. Metabolic Adaptions/Reprogramming in Islet Beta-Cells in Response to Physiological Stimulators—What Are the Consequences. Antioxidants (Basel) 2022; 11:antiox11010108. [PMID: 35052612 PMCID: PMC8773416 DOI: 10.3390/antiox11010108] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/25/2022] Open
Abstract
Irreversible pancreatic β-cell damage may be a result of chronic exposure to supraphysiological glucose or lipid concentrations or chronic exposure to therapeutic anti-diabetic drugs. The β-cells are able to respond to blood glucose in a narrow concentration range and release insulin in response, following activation of metabolic pathways such as glycolysis and the TCA cycle. The β-cell cannot protect itself from glucose toxicity by blocking glucose uptake, but indeed relies on alternative metabolic protection mechanisms to avoid dysfunction and death. Alteration of normal metabolic pathway function occurs as a counter regulatory response to high nutrient, inflammatory factor, hormone or therapeutic drug concentrations. Metabolic reprogramming is a term widely used to describe a change in regulation of various metabolic enzymes and transporters, usually associated with cell growth and proliferation and may involve reshaping epigenetic responses, in particular the acetylation and methylation of histone proteins and DNA. Other metabolic modifications such as Malonylation, Succinylation, Hydroxybutyrylation, ADP-ribosylation, and Lactylation, may impact regulatory processes, many of which need to be investigated in detail to contribute to current advances in metabolism. By describing multiple mechanisms of metabolic adaption that are available to the β-cell across its lifespan, we hope to identify sites for metabolic reprogramming mechanisms, most of which are incompletely described or understood. Many of these mechanisms are related to prominent antioxidant responses. Here, we have attempted to describe the key β-cell metabolic adaptions and changes which are required for survival and function in various physiological, pathological and pharmacological conditions.
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Affiliation(s)
- Philip Newsholme
- Curtin Medical School and CHIRI, Curtin University, Perth, WA 6845, Australia
- Correspondence: (P.N.); (J.R.)
| | - Jordan Rowlands
- Curtin Medical School and CHIRI, Curtin University, Perth, WA 6845, Australia
- Correspondence: (P.N.); (J.R.)
| | - Roselyn Rose’Meyer
- School of Pharmacy and Medical Sciences, Griffith University, Gold Coast, QLD 4222, Australia;
| | - Vinicius Cruzat
- Faculty of Health, Torrens University Australia, Brisbane, QLD 4006, Australia;
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McCarty MF, DiNicolantonio JJ. Maintaining Effective Beta Cell Function in the Face of Metabolic Syndrome-Associated Glucolipotoxicity-Nutraceutical Options. Healthcare (Basel) 2021; 10:3. [PMID: 35052168 PMCID: PMC8775473 DOI: 10.3390/healthcare10010003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 11/16/2022] Open
Abstract
In people with metabolic syndrome, episodic exposure of pancreatic beta cells to elevated levels of both glucose and free fatty acids (FFAs)-or glucolipotoxicity-can induce a loss of glucose-stimulated insulin secretion (GSIS). This in turn can lead to a chronic state of glucolipotoxicity and a sustained loss of GSIS, ushering in type 2 diabetes. Loss of GSIS reflects a decline in beta cell glucokinase (GK) expression associated with decreased nuclear levels of the pancreatic and duodenal homeobox 1 (PDX1) factor that drives its transcription, along with that of Glut2 and insulin. Glucolipotoxicity-induced production of reactive oxygen species (ROS), stemming from both mitochondria and the NOX2 isoform of NADPH oxidase, drives an increase in c-Jun N-terminal kinase (JNK) activity that promotes nuclear export of PDX1, and impairs autocrine insulin signaling; the latter effect decreases PDX1 expression at the transcriptional level and up-regulates beta cell apoptosis. Conversely, the incretin hormone glucagon-like peptide-1 (GLP-1) promotes nuclear import of PDX1 via cAMP signaling. Nutraceuticals that quell an increase in beta cell ROS production, that amplify or mimic autocrine insulin signaling, or that boost GLP-1 production, should help to maintain GSIS and suppress beta cell apoptosis in the face of glucolipotoxicity, postponing or preventing onset of type 2 diabetes. Nutraceuticals with potential in this regard include the following: phycocyanobilin-an inhibitor of NOX2; agents promoting mitophagy and mitochondrial biogenesis, such as ferulic acid, lipoic acid, melatonin, berberine, and astaxanthin; myo-inositol and high-dose biotin, which promote phosphatidylinositol 3-kinase (PI3K)/Akt activation; and prebiotics/probiotics capable of boosting GLP-1 secretion. Complex supplements or functional foods providing a selection of these agents might be useful for diabetes prevention.
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Affiliation(s)
| | - James J. DiNicolantonio
- Department of Preventive Cardiology, Saint Luke’s Mid America Heart Institute, Kansas City, MO 64111, USA
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Šrámek J, Němcová-Fürstová V, Kovář J. Molecular Mechanisms of Apoptosis Induction and Its Regulation by Fatty Acids in Pancreatic β-Cells. Int J Mol Sci 2021; 22:4285. [PMID: 33924206 PMCID: PMC8074590 DOI: 10.3390/ijms22084285] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/09/2021] [Accepted: 04/16/2021] [Indexed: 02/06/2023] Open
Abstract
Pancreatic β-cell failure and death contribute significantly to the pathogenesis of type 2 diabetes. One of the main factors responsible for β-cell dysfunction and subsequent cell death is chronic exposure to increased concentrations of FAs (fatty acids). The effect of FAs seems to depend particularly on the degree of their saturation. Saturated FAs induce apoptosis in pancreatic β-cells, whereas unsaturated FAs are well tolerated and are even capable of inhibiting the pro-apoptotic effect of saturated FAs. Molecular mechanisms of apoptosis induction by saturated FAs in β-cells are not completely elucidated. Saturated FAs induce ER stress, which in turn leads to activation of all ER stress pathways. When ER stress is severe or prolonged, apoptosis is induced. The main mediator seems to be the CHOP transcription factor. Via regulation of expression/activity of pro- and anti-apoptotic Bcl-2 family members, and potentially also through the increase in ROS production, CHOP switches on the mitochondrial pathway of apoptosis induction. ER stress signalling also possibly leads to autophagy signalling, which may activate caspase-8. Saturated FAs activate or inhibit various signalling pathways, i.e., p38 MAPK signalling, ERK signalling, ceramide signalling, Akt signalling and PKCδ signalling. This may lead to the activation of the mitochondrial pathway of apoptosis, as well. Particularly, the inhibition of the pro-survival Akt signalling seems to play an important role. This inhibition may be mediated by multiple pathways (e.g., ER stress signalling, PKCδ and ceramide) and could also consequence in autophagy signalling. Experimental evidence indicates the involvement of certain miRNAs in mechanisms of FA-induced β-cell apoptosis, as well. In the rather rare situations when unsaturated FAs are also shown to be pro-apoptotic, the mechanisms mediating this effect in β-cells seem to be the same as for saturated FAs. To conclude, FA-induced apoptosis rather appears to be preceded by complex cross talks of multiple signalling pathways. Some of these pathways may be regulated by decreased membrane fluidity due to saturated FA incorporation. Few data are available concerning molecular mechanisms mediating the protective effect of unsaturated FAs on the effect of saturated FAs. It seems that the main possible mechanism represents a rather inhibitory intervention into saturated FA-induced pro-apoptotic signalling than activation of some pro-survival signalling pathway(s) or metabolic interference in β-cells. This inhibitory intervention may be due to an increase of membrane fluidity.
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Affiliation(s)
- Jan Šrámek
- Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague, Czech Republic;
| | - Vlasta Němcová-Fürstová
- Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague, Czech Republic;
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Liu Y, Zeng Y, Miao Y, Cheng X, Deng S, Hao X, Jiang Y, Wan Q. Relationships among pancreatic beta cell function, the Nrf2 pathway, and IRS2: a cross-sectional study. Postgrad Med 2020; 132:720-726. [PMID: 32757691 DOI: 10.1080/00325481.2020.1797311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVES This study aimed to investigate the relationships among islet function, the Nrf2 pathway, and insulin receptor substrate 2 (IRS2) in type 2 diabetes mellitus (T2DM), prediabetes mellitus (IGR), and normal glucose tolerance (NGT) populations. METHODS Three hundred cases each were selected for the NGT, IGR, and T2DM groups; FBG, 2hPG, HbA1 c, FINS, TG, TC, HDL-C, and LDL-C levels and serum levels of nuclear factor in E2-related factor 2 (Nrf2), insulin receptor substrate 2 (IRS2), tumor necrosis factor alpha (TNF-α), and heme oxygenase 1 (HO-1) were evaluated. RESULTS The T2DM group had lower islet β-cell function index and insulin sensitivity index than the NGT and IGR groups (P < 0.05). The Nrf2, IRS2, and HO-1 levels in the NGT, IGR, and T2DM groups followed a decreasing trend in the order mentioned, whereas the TNF-α levels followed an increasing trend. CONCLUSIONS Upon impairment of glucose regulation, the expression of TNF-α in the human body increased, which indicated the aggravation of oxidative stress (OS) and the inflammatory response. Islet function was maintained in the pre-diabetic population, and concurrently, the TNF-α, Nrf2, and HO-1 levels were moderately elevated, the expression of IRS2 was marginally inhibited, and the Nrf2 pathway was activated under mild OS stimulus to resist OS, inflammation, and injury, which may have been mediated through PI3 K/AKT. In patients with T2DM, islet function was significantly poorer, TNF-α amplification was enhanced significantly, and Nrf2, HO-1, and IRS2 expression reduced significantly; this suggested that, along with the aggravation of OS and the inflammatory response, Nrf2 pathway activation and HO-1 expression were both inhibited, the antioxidant capacity of the body was reduced, IRS2 degradation increased, and islet function was impaired.
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Affiliation(s)
- Yiying Liu
- Department of Endocrinology, The Affiliated Hospital of Southwest Medical University , Luzhou, Sichuan, China.,Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy
| | - Yue Zeng
- Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy.,Department of Endocrinology, Longchang People's Hospital , Neijiang, Sichuan, China
| | - Ying Miao
- Department of Endocrinology, The Affiliated Hospital of Southwest Medical University , Luzhou, Sichuan, China.,Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy
| | - Xiaoling Cheng
- Department of Endocrinology, The Affiliated Hospital of Southwest Medical University , Luzhou, Sichuan, China.,Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy
| | - Sijie Deng
- Department of Endocrinology, The Affiliated Hospital of Southwest Medical University , Luzhou, Sichuan, China.,Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy
| | - Xinlin Hao
- Department of Endocrinology, The Affiliated Hospital of Southwest Medical University , Luzhou, Sichuan, China.,Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy
| | - Yuefei Jiang
- Department of Endocrinology, The Affiliated Hospital of Southwest Medical University , Luzhou, Sichuan, China.,Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy
| | - Qin Wan
- Department of Endocrinology, The Affiliated Hospital of Southwest Medical University , Luzhou, Sichuan, China.,Key Laboratory of Cardiovascular and Metabolism of LuZhou City.,SiChuan Clinical Research Center for Nephropathy
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Jara MA, Werneck-De-Castro JP, Lubaczeuski C, Johnson JD, Bernal-Mizrachi E. Pancreatic and duodenal homeobox-1 (PDX1) contributes to β-cell mass expansion and proliferation induced by Akt/PKB pathway. Islets 2020; 12:32-40. [PMID: 32876522 PMCID: PMC7527019 DOI: 10.1080/19382014.2020.1762471] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Maintenance of pancreatic β-cell mass and function is fundamental to glucose homeostasis and to prevent diabetes. The PI3 K-Akt-mTORC1 pathway is critical for β-cells mass and function, while PDX1 has been implicated in β-cell development, maturation, and function. Here we tested whether Akt signaling requires PDX1 expression to regulate β-cell mass, proliferation, and glucose homeostasis. In order to address that, we crossed a mouse model overexpressing constitutively active Akt mutant in β-cells (β-caAkt) with mice lacking one allele of PDX1gene (β-caAkt/pdx1+/-). While the β-caAkt mice exhibit higher plasma insulin levels, greater β-cell mass and improved glucose tolerance compared to control mice, the β-caAkt/pdx1+/- mice are hyperglycemic and intolerant to glucose. The changes in glucose homeostasis in β-caAkt/pdx1+/- were associated with a 60% reduction in β-cell mass compared to β-caAkt mice. The impaired β-cell mass in the β-caAkt/pdx1+/- mice can be explained by a lesser β-cell proliferation measured by the number of Ki67 positive β-cells. We did not observe any differences in apoptosis between β-caAkt/pdx1+/- and β-caAkt mice. In conclusion, PDX1 contributes to β-cell mass expansion and glucose metabolism induced by activation of Akt signaling.
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Affiliation(s)
- Mark Anthony Jara
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Joao Pedro Werneck-De-Castro
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
- Miami VA Health Care System, Miami, FL, USA
| | - Camila Lubaczeuski
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - James D. Johnson
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Miller School of Medicine, University of Miami, Miami, FL, USA
- Miami VA Health Care System, Miami, FL, USA
- CONTACT Ernesto Bernal-Mizrachi Department Of Internal Medicine, Division Of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL33136, USA
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Lu M, Ma L, Shan P, Liu A, Yu X, Jiang W, Wang X, Zhao X, Ye X, Wang T. DYRK1A aggravates β cell dysfunction and apoptosis by promoting the phosphorylation and degradation of IRS2. Exp Gerontol 2019; 125:110659. [PMID: 31306739 DOI: 10.1016/j.exger.2019.110659] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 07/12/2019] [Accepted: 07/12/2019] [Indexed: 01/21/2023]
Abstract
In this study, we aimed to investigate the role of dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A), which is one of the most important regulators of Alzheimer's disease development, in islet β cell dysfunction and apoptosis. We found significantly increased expression of DYRK1A in both the hippocampus and pancreatic islets of APPswe/PS1ΔE9 transgenic mice than in wild-type littermates. Furthermore, we observed that the overexpression of DYRK1A greatly aggravated β cell apoptosis. Most importantly, we found that DYRK1A directly interacted with insulin receptor substrate-2 (IRS2) and promoted IRS2 phosphorylation, leading to the proteasomal degradation of IRS2 and promotion of β cell dysfunction and apoptosis. These findings suggested that DYRK1A is a potential drug target in diabetes mellitus.
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Affiliation(s)
- Mei Lu
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China; Shandong Provincial Key laboratory of Cardiovascular Proteomics, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Lin Ma
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China; Shandong Provincial Key laboratory of Cardiovascular Proteomics, Qilu Hospital of Shandong University, Jinan, Shandong, China.
| | - Peiyan Shan
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China; Shandong Provincial Key laboratory of Cardiovascular Proteomics, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Aifen Liu
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xiaolin Yu
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Wenjing Jiang
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xinbang Wang
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xinjing Zhao
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xiang Ye
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Tan Wang
- Department of Geriatric Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
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10
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Liu J, Carnero-Montoro E, van Dongen J, Lent S, Nedeljkovic I, Ligthart S, Tsai PC, Martin TC, Mandaviya PR, Jansen R, Peters MJ, Duijts L, Jaddoe VWV, Tiemeier H, Felix JF, Willemsen G, de Geus EJC, Chu AY, Levy D, Hwang SJ, Bressler J, Gondalia R, Salfati EL, Herder C, Hidalgo BA, Tanaka T, Moore AZ, Lemaitre RN, Jhun MA, Smith JA, Sotoodehnia N, Bandinelli S, Ferrucci L, Arnett DK, Grallert H, Assimes TL, Hou L, Baccarelli A, Whitsel EA, van Dijk KW, Amin N, Uitterlinden AG, Sijbrands EJG, Franco OH, Dehghan A, Spector TD, Dupuis J, Hivert MF, Rotter JI, Meigs JB, Pankow JS, van Meurs JBJ, Isaacs A, Boomsma DI, Bell JT, Demirkan A, van Duijn CM. An integrative cross-omics analysis of DNA methylation sites of glucose and insulin homeostasis. Nat Commun 2019; 10:2581. [PMID: 31197173 PMCID: PMC6565679 DOI: 10.1038/s41467-019-10487-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 05/09/2019] [Indexed: 02/07/2023] Open
Abstract
Despite existing reports on differential DNA methylation in type 2 diabetes (T2D) and obesity, our understanding of its functional relevance remains limited. Here we show the effect of differential methylation in the early phases of T2D pathology by a blood-based epigenome-wide association study of 4808 non-diabetic Europeans in the discovery phase and 11,750 individuals in the replication. We identify CpGs in LETM1, RBM20, IRS2, MAN2A2 and the 1q25.3 region associated with fasting insulin, and in FCRL6, SLAMF1, APOBEC3H and the 15q26.1 region with fasting glucose. In silico cross-omics analyses highlight the role of differential methylation in the crosstalk between the adaptive immune system and glucose homeostasis. The differential methylation explains at least 16.9% of the association between obesity and insulin. Our study sheds light on the biological interactions between genetic variants driving differential methylation and gene expression in the early pathogenesis of T2D.
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Affiliation(s)
- Jun Liu
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands. .,Nuffield Department of Population Health, University of Oxford, Oxford, OX3 7FL, UK.
| | - Elena Carnero-Montoro
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Center for Genomics and Oncological Research, GENYO, Pfizer/University of Granada/Andalusian Government, PTS, Granada, 18007, Spain.,Department of Twin Research and Genetic Epidemiology, King's College London, London, WC2R 2LS, UK
| | - Jenny van Dongen
- Department of Biological Psychology, Amsterdam Public Health (APH) research institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, 1081BT, The Netherlands
| | - Samantha Lent
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, 02118, USA
| | - Ivana Nedeljkovic
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Symen Ligthart
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Pei-Chien Tsai
- Department of Twin Research and Genetic Epidemiology, King's College London, London, WC2R 2LS, UK.,Department of Biomedical Sciences, Chang Gung University, Taoyuan, 333, Taiwan.,Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital, Linkou, 333, Taiwan
| | - Tiphaine C Martin
- Department of Twin Research and Genetic Epidemiology, King's College London, London, WC2R 2LS, UK.,Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.,The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Pooja R Mandaviya
- Department of Internal Medicine, Section of Pharmacology Vascular and Metabolic Diseases, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Rick Jansen
- Department of Psychiatry and Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, 1081BT, The Netherlands
| | - Marjolein J Peters
- Department of Internal Medicine, Section of Pharmacology Vascular and Metabolic Diseases, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Liesbeth Duijts
- Division of Neonatology, Department of Pediatrics, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Division of Respiratory Medicine, Department of Pediatrics, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Vincent W V Jaddoe
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Department of Pediatrics, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Generation R Study Group, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Henning Tiemeier
- Department of Child and Adolescent Psychiatry, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Department of Social and Behavioral Science, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA
| | - Janine F Felix
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Department of Pediatrics, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Generation R Study Group, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Gonneke Willemsen
- Department of Biological Psychology, Amsterdam Public Health (APH) research institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, 1081BT, The Netherlands
| | - Eco J C de Geus
- Department of Biological Psychology, Amsterdam Public Health (APH) research institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, 1081BT, The Netherlands
| | - Audrey Y Chu
- The Population Sciences Branch, Division of Intramural Research, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20814, USA.,The Framingham Heart Study, National Heart, Lung and Blood Institute, National Institutes of Health, Framingham, MA, 01702, USA
| | - Daniel Levy
- The Population Sciences Branch, Division of Intramural Research, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20814, USA.,The Framingham Heart Study, National Heart, Lung and Blood Institute, National Institutes of Health, Framingham, MA, 01702, USA
| | - Shih-Jen Hwang
- The Population Sciences Branch, Division of Intramural Research, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20814, USA.,The Framingham Heart Study, National Heart, Lung and Blood Institute, National Institutes of Health, Framingham, MA, 01702, USA
| | - Jan Bressler
- Human Genetics Center, School of Public Health, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Rahul Gondalia
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Elias L Salfati
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Christian Herder
- German Center for Diabetes Research (DZD), München-Neuherberg, 85764, Germany.,Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany.,Division of Endocrinology and Diabetology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Bertha A Hidalgo
- Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL, 35233, USA
| | - Toshiko Tanaka
- Translational Gerontology Branch, National Institute on Aging, Baltimore, MD, 21224, USA
| | - Ann Zenobia Moore
- Translational Gerontology Branch, National Institute on Aging, Baltimore, MD, 21224, USA
| | - Rozenn N Lemaitre
- Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, WA, 98101, USA
| | - Min A Jhun
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jennifer A Smith
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Nona Sotoodehnia
- Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, WA, 98101, USA
| | | | - Luigi Ferrucci
- Translational Gerontology Branch, National Institute on Aging, Baltimore, MD, 21224, USA
| | - Donna K Arnett
- School of Public Health, University of Kentucky, Lexington, KY, 40536, USA
| | - Harald Grallert
- German Center for Diabetes Research (DZD), München-Neuherberg, 85764, Germany.,Research Unit of Molecular Epidemiology, Institute of Epidemiology, Helmholtz Zentrum München Research Center for Environmental Health, Neuherberg, 85764, Germany
| | - Themistocles L Assimes
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Lifang Hou
- Center for Population Epigenetics, Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University Chicago, Evanston, IL, 60611, USA.,Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Andrea Baccarelli
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, 10032, USA
| | - Eric A Whitsel
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA.,Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina, NC, 27516, USA
| | - Ko Willems van Dijk
- Department of Human Genetics, Leiden University Medical Center, Leiden, 2333ZA, The Netherlands.,Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, 2333ZA, The Netherlands
| | - Najaf Amin
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - André G Uitterlinden
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Department of Internal Medicine, Section of Pharmacology Vascular and Metabolic Diseases, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Eric J G Sijbrands
- Department of Internal Medicine, Section of Pharmacology Vascular and Metabolic Diseases, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands
| | - Oscar H Franco
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, 3012, Switzerland
| | - Abbas Dehghan
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,Department of Epidemiology and Biostatistics, Imperial College London, London, SW7 2AZ, UK
| | - Tim D Spector
- Department of Twin Research and Genetic Epidemiology, King's College London, London, WC2R 2LS, UK
| | - Josée Dupuis
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, 02118, USA
| | - Marie-France Hivert
- Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, J1K0A5, Canada.,Diabetes Unit, Massachusetts General Hospital, Boston, MA, 02114, USA.,Division of Chronic Disease Research Across the Lifecourse, Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, 02215, USA
| | - Jerome I Rotter
- The Institute for Translational Genomics and Population Sciences and Departments of Pediatrics and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, 90502, USA
| | - James B Meigs
- Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA.,Division of General Internal Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA.,Programs in Metabolism and Medical & Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - James S Pankow
- Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Joyce B J van Meurs
- CARIM School for Cardiovascular Diseases, Maastricht Centre for Systems Biology (MaCSBio), and Departments of Biochemistry and Physiology, Maastricht University, Maastricht, 6211LK, The Netherlands
| | - Aaron Isaacs
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands.,CARIM School for Cardiovascular Diseases, Maastricht Centre for Systems Biology (MaCSBio), and Departments of Biochemistry and Physiology, Maastricht University, Maastricht, 6211LK, The Netherlands
| | - Dorret I Boomsma
- Department of Biological Psychology, Amsterdam Public Health (APH) research institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, 1081BT, The Netherlands
| | - Jordana T Bell
- Department of Twin Research and Genetic Epidemiology, King's College London, London, WC2R 2LS, UK
| | - Ayşe Demirkan
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands. .,Department of Genetics, University Medical Center Groningen, Groningen, 9713GZ, The Netherlands. .,Section of Statistical Multi-Omics, Department of Experimental and Clinical Research, School of Bioscience and Medicine, Univeristy of Surrey, Guildford, GU2 7XH, UK.
| | - Cornelia M van Duijn
- Department of Epidemiology, Erasmus University Medical Center, Rotterdam, 3015GD, The Netherlands. .,Nuffield Department of Population Health, University of Oxford, Oxford, OX3 7FL, UK. .,Leiden Academic Center for Drug Research, Leiden University, Leiden, 2311EZ, The Netherlands.
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11
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Isaac R, Vinik Y, Boura-Halfon S, Farack L, Streim S, Elhanany E, Kam Z, Zick Y. Prolonged Elimination of Negative Feedback Control Mechanisms Along the Insulin Signaling Pathway Impairs β-Cell Function In Vivo. Diabetes 2017; 66:1879-1889. [PMID: 28424159 DOI: 10.2337/db16-0827] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 04/06/2017] [Indexed: 11/13/2022]
Abstract
Cellular stress and proinflammatory cytokines induce phosphorylation of insulin receptor substrate (IRS) proteins at Ser sites that inhibit insulin and IGF-I signaling. We therefore examined the effects of mutation of five "inhibitory" Ser phosphorylation sites on IRS2 function in transgenic mice that overexpress, selectively in pancreatic β-cells, either wild-type (WT) or a mutated IRS2 protein (IRS25A). Islets size, number, and mRNA levels of catalase and superoxide dismutase were increased, whereas those of nitric oxide synthase were decreased, in 7- to 10-week-old IRS25A-β mice compared with IRS2WT-β mice. However, glucose homeostasis and insulin secretion in IRS25A-β mice were impaired when compared with IRS2WT-β mice or to nontransgenic mice. This was associated with reduced mRNA levels of Glut2 and islet β-cell transcription factors such as Nkx6.1 and MafA Similarly, components mediating the unfolded protein response were decreased in islets of IRS25A-β mice in accordance with their decreased insulin secretion. The beneficial effects of IRS25A on β-cell proliferation and β-cell transcription factors were evident only in 5- to 8-day-old mice. These findings suggest that elimination of inhibitory Ser phosphorylation sites of IRS2 exerts short-term beneficial effects in vivo; however, their sustained elimination leads to impaired β-cell function.
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Affiliation(s)
- Roi Isaac
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Yaron Vinik
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Sigalit Boura-Halfon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Lydia Farack
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Sarina Streim
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Eytan Elhanany
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Zvi Kam
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Yehiel Zick
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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12
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Linyi L, Yoshitomi H, Lingling Q, Xinli W, Tian Z, Haiyan W, Yueying J, Ying W, Tunhai X, Tonghua L, Ming G. Tangnaikang improves insulin resistance and β-cell apoptosis by ameliorating metabolic inflammation in SHR.Cg-Lepr cp /NDmcr rats. J TRADIT CHIN MED 2017. [DOI: 10.1016/s0254-6272(17)30072-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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13
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Sebastiani G, Guarino E, Grieco GE, Formichi C, Delli Poggi C, Ceccarelli E, Dotta F. Circulating microRNA (miRNA) Expression Profiling in Plasma of Patients with Gestational Diabetes Mellitus Reveals Upregulation of miRNA miR-330-3p. Front Endocrinol (Lausanne) 2017; 8:345. [PMID: 29312141 PMCID: PMC5732927 DOI: 10.3389/fendo.2017.00345] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/27/2017] [Indexed: 12/20/2022] Open
Abstract
Gestational diabetes mellitus (GDM) is characterized by insulin resistance accompanied by low/absent beta-cell compensatory adaptation to the increased insulin demand. Although the molecular mechanisms and factors acting on beta-cell compensatory response during pregnancy have been partially elucidated and reported, those inducing an impaired beta-cell compensation and function, thus evolving in GDM, have yet to be fully addressed. MicroRNAs (miRNAs) are a class of small endogenous non-coding RNAs, which negatively modulate gene expression through their sequence-specific binding to 3'UTR of mRNA target. They have been described as potent modulators of cell survival and proliferation and, furthermore, as orchestrating molecules of beta-cell compensatory response and function in diabetes. Moreover, it has been reported that miRNAs can be actively secreted by cells and found in many biological fluids (e.g., serum/plasma), thus representing both optimal candidate disease biomarkers and mediators of tissues crosstalk(s). Here, we analyzed the expression profiles of circulating miRNAs in plasma samples obtained from n = 21 GDM patients and from n = 10 non-diabetic control pregnant women (24-33 weeks of gestation) using TaqMan array microfluidics cards followed by RT-real-time PCR single assay validation. The results highlighted the upregulation of miR-330-3p in plasma of GDM vs non-diabetics. Furthermore, the analysis of miR-330-3p expression levels revealed a bimodally distributed GDM patients group characterized by high or low circulating miR-330 expression and identified as GDM-miR-330high and GDM-miR-330low. Interestingly, GDM-miR-330high subgroup retained lower levels of insulinemia, inversely correlated to miR-330-3p expression levels, and a significant higher rate of primary cesarean sections. Finally, miR-330-3p target genes analysis revealed major modulators of beta-cell proliferation and of insulin secretion, such as the experimentally validated genes E2F1 and CDC42 as well as AGT2R2, a gene involved in the differentiation of mature beta-cells. In conclusion, we demonstrated that plasma miR-330-3p could be of help in identifying GDM patients with potential worse gestational diabetes outcome; in GDM, miR-330-3p may directly be transferred from plasma to beta-cells thus modulating key target genes involved in proliferation, differentiation, and insulin secretion.
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Affiliation(s)
- Guido Sebastiani
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto di Mario, Toscana Life Sciences, Siena, Italy
| | - Elisa Guarino
- Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Giuseppina Emanuela Grieco
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto di Mario, Toscana Life Sciences, Siena, Italy
| | - Caterina Formichi
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto di Mario, Toscana Life Sciences, Siena, Italy
| | - Chiara Delli Poggi
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto di Mario, Toscana Life Sciences, Siena, Italy
| | - Elena Ceccarelli
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
| | - Francesco Dotta
- Diabetes Unit, Department of Medicine, Surgery and Neurosciences, University of Siena, Siena, Italy
- Fondazione Umberto di Mario, Toscana Life Sciences, Siena, Italy
- Azienda Ospedaliera Universitaria Senese, Siena, Italy
- *Correspondence: Francesco Dotta,
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14
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Pan-cancer analysis of somatic copy-number alterations implicates IRS4 and IGF2 in enhancer hijacking. Nat Genet 2016; 49:65-74. [PMID: 27869826 DOI: 10.1038/ng.3722] [Citation(s) in RCA: 289] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 10/19/2016] [Indexed: 02/06/2023]
Abstract
Extensive prior research focused on somatic copy-number alterations (SCNAs) affecting cancer genes, yet the extent to which recurrent SCNAs exert their influence through rearrangement of cis-regulatory elements (CREs) remains unclear. Here we present a framework for inferring cancer-related gene overexpression resulting from CRE reorganization (e.g., enhancer hijacking) by integrating SCNAs, gene expression data and information on topologically associating domains (TADs). Analysis of 7,416 cancer genomes uncovered several pan-cancer candidate genes, including IRS4, SMARCA1 and TERT. We demonstrate that IRS4 overexpression in lung cancer is associated with recurrent deletions in cis, and we present evidence supporting a tumor-promoting role. We additionally pursued cancer-type-specific analyses and uncovered IGF2 as a target for enhancer hijacking in colorectal cancer. Recurrent tandem duplications intersecting with a TAD boundary mediate de novo formation of a 3D contact domain comprising IGF2 and a lineage-specific super-enhancer, resulting in high-level gene activation. Our framework enables systematic inference of CRE rearrangements mediating dysregulation in cancer.
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15
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Baquedano E, Burgos-Ramos E, Canelles S, González-Rodríguez A, Chowen JA, Argente J, Barrios V, Valverde AM, Frago LM. Increased oxidative stress and apoptosis in the hypothalamus of diabetic male mice in the insulin receptor substrate-2 knockout model. Dis Model Mech 2016; 9:573-83. [PMID: 27013528 PMCID: PMC4892662 DOI: 10.1242/dmm.023515] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 03/11/2016] [Indexed: 01/12/2023] Open
Abstract
Insulin receptor substrate-2-deficient (IRS2(-/-)) mice are considered a good model to study the development of diabetes because IRS proteins mediate the pleiotropic effects of insulin-like growth factor-I (IGF-I) and insulin on metabolism, mitogenesis and cell survival. The hypothalamus might play a key role in the early onset of diabetes, owing to its involvement in the control of glucose homeostasis and energy balance. Because some inflammatory markers are elevated in the hypothalamus of diabetic IRS2(-/-) mice, our aim was to analyze whether the diabetes associated with the absence of IRS2 results in hypothalamic injury and to analyze the intracellular mechanisms involved. Only diabetic IRS2(-/-) mice showed increased cell death and activation of caspase-8 and -3 in the hypothalamus. Regulators of apoptosis such as FADD, Bcl-2, Bcl-xL and p53 were also increased, whereas p-IκB and c-FLIPL were decreased. This was accompanied by increased levels of Nox-4 and catalase, enzymes involved in oxidative stress. In summary, the hypothalamus of diabetic IRS2(-/-) mice showed an increase in oxidative stress and inflammatory markers that finally resulted in cell death via substantial activation of the extrinsic apoptotic pathway. Conversely, non-diabetic IRS2(-/-) mice did not show cell death in the hypothalamus, possibly owing to an increase in the levels of circulating IGF-I and in the enhanced hypothalamic IGF-IR phosphorylation that would lead to the stimulation of survival pathways. In conclusion, diabetes in IRS2-deficient male mice is associated with increased oxidative stress and apoptosis in the hypothalamus.
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Affiliation(s)
- Eva Baquedano
- Department of Paediatrics, Universidad Autónoma de Madrid, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Instituto de Investigación Sanitaria Princesa, IIS-IP, Madrid E-28006, Spain Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Emma Burgos-Ramos
- Department of Paediatrics, Universidad Autónoma de Madrid, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Instituto de Investigación Sanitaria Princesa, IIS-IP, Madrid E-28006, Spain Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Sandra Canelles
- Department of Paediatrics, Universidad Autónoma de Madrid, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Instituto de Investigación Sanitaria Princesa, IIS-IP, Madrid E-28006, Spain Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Agueda González-Rodríguez
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid, Madrid E-28029, Spain Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Julie A Chowen
- Department of Paediatrics, Universidad Autónoma de Madrid, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Instituto de Investigación Sanitaria Princesa, IIS-IP, Madrid E-28006, Spain Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Jesús Argente
- Department of Paediatrics, Universidad Autónoma de Madrid, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Instituto de Investigación Sanitaria Princesa, IIS-IP, Madrid E-28006, Spain Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Vicente Barrios
- Department of Paediatrics, Universidad Autónoma de Madrid, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Instituto de Investigación Sanitaria Princesa, IIS-IP, Madrid E-28006, Spain Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Angela M Valverde
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid, Madrid E-28029, Spain Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid E-28029, Spain
| | - Laura M Frago
- Department of Paediatrics, Universidad Autónoma de Madrid, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Av. Menéndez Pelayo, 65, Madrid 28009, Spain Instituto de Investigación Sanitaria Princesa, IIS-IP, Madrid E-28006, Spain Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid E-28029, Spain
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16
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Arous C, Halban PA. The skeleton in the closet: actin cytoskeletal remodeling in β-cell function. Am J Physiol Endocrinol Metab 2015; 309:E611-20. [PMID: 26286869 DOI: 10.1152/ajpendo.00268.2015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/11/2015] [Indexed: 01/13/2023]
Abstract
Over the last few decades, biomedical research has considered not only the function of single cells but also the importance of the physical environment within a whole tissue, including cell-cell and cell-extracellular matrix interactions. Cytoskeleton organization and focal adhesions are crucial sensors for cells that enable them to rapidly communicate with the physical extracellular environment in response to extracellular stimuli, ensuring proper function and adaptation. The involvement of the microtubular-microfilamentous cytoskeleton in secretion mechanisms was proposed almost 50 years ago, since when the evolution of ever more sensitive and sophisticated methods in microscopy and in cell and molecular biology have led us to become aware of the importance of cytoskeleton remodeling for cell shape regulation and its crucial link with signaling pathways leading to β-cell function. Emerging evidence suggests that dysfunction of cytoskeletal components or extracellular matrix modification influences a number of disorders through potential actin cytoskeleton disruption that could be involved in the initiation of multiple cellular functions. Perturbation of β-cell actin cytoskeleton remodeling could arise secondarily to islet inflammation and fibrosis, possibly accounting in part for impaired β-cell function in type 2 diabetes. This review focuses on the role of actin remodeling in insulin secretion mechanisms and its close relationship with focal adhesions and myosin II.
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Affiliation(s)
- Caroline Arous
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
| | - Philippe A Halban
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
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Tsai CY, Larson CA, Safaei R, Howell SB. Molecular modulation of the copper and cisplatin transport function of CTR1 and its interaction with IRS-4. Biochem Pharmacol 2014; 90:379-87. [PMID: 24967972 DOI: 10.1016/j.bcp.2014.06.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 01/29/2023]
Abstract
The copper influx transporter CTR1 is also a major influx transporter for cisplatin (cDDP) in tumor cells. It influences the cytotoxicity of cDDP both in vivo and in vitro. Whereas Cu triggers internalization of CTR1 from the plasma membrane, cDDP does not. To investigate the mechanisms of these effects, myc-tagged forms of wild type hCTR1 and variants in which Y103 was converted to alanine, C189 was converted to serine, or the K178/K179 dilysine motif was converted to alanines were re-expressed in mouse embryo cells in which both alleles of CTR1 had been knocked out and also in HEK293T cells. The Y103A mutation and to a lesser extent the C189S mutation reduced internalization of CTR1 induced by Cu while the K178A/K179A had little effect. Both Y103 and C189 were required for Cu and cDDP transport whereas the K178/K179 motif was not. While Y103 lies in an YXXM motif that, when phosphorylated, is a potential docking site for phosphatidylinositol 3-kinase and other proteins involved in endocytosis, Western blot analysis of immunoprecipitated myc-CTR1, and proteomic analysis of peptides derived from CTR1, failed to identify any basal or Cu-induced phosphorylation. However, proteomic analysis did identify an interaction of CTR1 with IRS-4 and this was confirmed by co-immunoprecipitation from HEK cells expressing either FLAG-CTR1 or myc-CTR1. The interaction was greater in the Y103A-expressing cells. We conclude that Y103 is required for the internalization of hCTR1 in response to Cu, that this occurs by a mechanism other than phosphorylation and that mutation of Y103 modulates the interaction with IRS-4.
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Affiliation(s)
- Cheng-Yu Tsai
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA.
| | - Christopher A Larson
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA.
| | - Roohangiz Safaei
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA
| | - Stephen B Howell
- Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA; Department of Medicine, University of California, San Diego, 3855 Health Sciences Drive, Mail Code 0819, La Jolla, CA 92093-0819, USA.
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18
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Lee JH, Jung IR, Choi SE, Lee SM, Lee SJ, Han SJ, Kim HJ, Kim DJ, Lee KW, Kang Y. Toxicity generated through inhibition of pyruvate carboxylase and carnitine palmitoyl transferase-1 is similar to high glucose/palmitate-induced glucolipotoxicity in INS-1 beta cells. Mol Cell Endocrinol 2014; 383:48-59. [PMID: 24333689 DOI: 10.1016/j.mce.2013.12.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 11/14/2013] [Accepted: 12/01/2013] [Indexed: 01/22/2023]
Abstract
This work was initiated to determine whether toxicity generated through inhibition of mitochondrial fuel metabolism is similar to high glucose/palmitate (HG/PA)-induced glucolipotoxicity. Influx of glucose and free fatty acids into the tricarboxylic acid (TCA) cycle was inhibited by treatment with the pyruvate carboxylase (PC) inhibitor phenylacetic acid (PAA) and carnitine palmitoyl transferase-1 (CPT-1) inhibitor etomoxir (Eto), or knockdown of PC and CPT-1. Treatment of PAA/Eto or knockdown of PC/CPT-1 induced apoptotic death in INS-1 beta cells. Similar to HG/PA treatment, PAA/Eto increased endoplasmic reticulum stress responses but decreased the Akt signal. JNK inhibitor or chemical chaperone was protective against both PAA/Eto- and HG/PA-induced cell death. All attempts to reduce [Ca²⁺](i), stimulate lipid metabolism, and increase the TCA cycle intermediate pool protected PAA/Eto-induced death as well as HG/PA-induced death. These data suggest that signals induced from impaired mitochondrial fuel metabolism play a critical role in HG/PA-induced glucolipotoxicity.
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Affiliation(s)
- Ji-Hyun Lee
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea; Department of Life Science, Korea University Seoul 136-701, Republic of Korea
| | - Ik-Rak Jung
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Sung-E Choi
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Sung-Mi Lee
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Soo-Jin Lee
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Seung Jin Han
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Hae Jin Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Dae Jung Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Kwan-Woo Lee
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Yup Kang
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea.
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Huang Y, Chang Y. Regulation of pancreatic islet beta-cell mass by growth factor and hormone signaling. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 121:321-49. [PMID: 24373242 DOI: 10.1016/b978-0-12-800101-1.00010-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Dysfunction and destruction of pancreatic islet beta cells is a hallmark of diabetes. Better understanding of cellular signals in beta cells will allow development of therapeutic strategies for diabetes, such as preservation and expansion of beta-cell mass and improvement of beta-cell function. During the past several decades, the number of studies analyzing the molecular mechanisms, including growth factor/hormone signaling pathways that impact islet beta-cell mass and function, has increased exponentially. Notably, somatolactogenic hormones including growth hormone (GH), prolactin (PRL), and insulin-like growth factor-1 (IGF-1) and their receptors (GHR, PRLR, and IGF-1R) are critically involved in beta-cell growth, survival, differentiation, and insulin secretion. In this chapter, we focus more narrowly on GH, PRL, and IGF-1 signaling, and GH-IGF-1 cross talk. We also discuss how these signaling aspects contribute to the regulation of beta-cell proliferation and apoptosis. In particular, our novel findings of GH-induced formation of GHR-JAK2-IGF-1R protein complex and synergistic effects of GH and IGF-1 on beta-cell signaling, proliferation, and antiapoptosis lead to a new concept that IGF-1R may serve as a proximal component of GH/GHR signaling.
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Affiliation(s)
- Yao Huang
- Department of Obstetrics and Gynecology, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Yongchang Chang
- Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
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Hoxhaj G, Dissanayake K, MacKintosh C. Effect of IRS4 levels on PI 3-kinase signalling. PLoS One 2013; 8:e73327. [PMID: 24039912 PMCID: PMC3769281 DOI: 10.1371/journal.pone.0073327] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/25/2013] [Indexed: 11/20/2022] Open
Abstract
Insulin receptor substrate 1 (IRS1) and IRS2 are well-characterized adapter proteins that relay signals from receptor tyrosine kinases to downstream components of signalling pathways. In contrast, the function of IRS4 is not well understood. IRS4 overexpression has been associated with acute lymphoblastic leukaemia and subungual exostosis, while point mutations of IRS4 have been found in melanomas. Here, we show that while IRS4 expression is low in most cancer cell lines, IRS4 mRNA and protein levels are markedly elevated in certain cells including the NCI-H720, DMS114, HEK293T and HEK293AAV lines. Surprisingly, IRS4 expression was also strongly induced when HEK293 cells were infected with retroviral particles and selected under puromycin, making IRS4 expression a potential off-target effect of retroviral expression vectors. Cells with high expression of IRS4 displayed high phosphatidylinositol (3,4,5)-trisphosphate (PIP3) levels, as well as elevated Akt and p70 S6 kinase activities, even in the absence of growth factors. PI 3-kinase (PI3K) signalling in these cells depends on IRS4, even though these cells also express IRS1/2. Knockdown of IRS4 also inhibited cell proliferation in cells with high levels of IRS4. Together, these findings suggest IRS4 as a potential therapeutic target for cancers with high expression of this protein.
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Affiliation(s)
- Gerta Hoxhaj
- Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Kumara Dissanayake
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
| | - Carol MacKintosh
- Medical Research Council Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
- Division of Cell and Developmental Biology, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom
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21
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Gui S, Yuan G, Wang L, Zhou L, Xue Y, Yu Y, Zhang J, Zhang M, Yang Y, Wang DW. Wnt3a regulates proliferation, apoptosis and function of pancreatic NIT-1 beta cells via activation of IRS2/PI3K signaling. J Cell Biochem 2013; 114:1488-97. [DOI: 10.1002/jcb.24490] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 12/21/2012] [Indexed: 01/07/2023]
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Liu B, Barbosa-Sampaio H, Jones PM, Persaud SJ, Muller DS. The CaMK4/CREB/IRS-2 cascade stimulates proliferation and inhibits apoptosis of β-cells. PLoS One 2012; 7:e45711. [PMID: 23049845 PMCID: PMC3458088 DOI: 10.1371/journal.pone.0045711] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 08/23/2012] [Indexed: 01/09/2023] Open
Abstract
Progressive reduction in β-cell mass is responsible for the development of type 2 diabetes mellitus, and alteration in insulin receptor substrate 2 (IRS-2) abundance plays a critical role in this process. IRS-2 expression is stimulated by the transcription factor cAMP response element-binding protein (CREB) and we recently demonstrated that Ca2+/calmodulin dependent kinase 4 (CaMK4) is upstream of CREB activation in β-cells. This study investigated whether CaMK4 is also a potential target to increase β-cell mass through CREB-mediated IRS-2 expression, by quantifying mouse MIN6 β-cell proliferation and apoptosis following IRS-2 knockdown, CaMKs inhibition and alterations in CaMK4 and CREB expression. Expression of constitutively active CaMK4 (ΔCaMK4) and CREB (CREBDIEDLM) significantly stimulated β-cell proliferation and survival. In contrast, expression of their corresponding dominant negative forms (ΔK75ECaMK4 and CREBM1) and silencing of IRS-2 increased apoptosis and reduced β-cell division. Moreover, CREBDIEDLM and CREBM1 expression completely abolished the effects of ΔK75ECaMK4 and of ΔCaMK4, respectively. Our results indicate that CaMK4 regulates β-cell proliferation and apoptosis in a CREB-dependent manner and that CaMK4-induced IRS-2 expression is important in these processes.
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Affiliation(s)
- Bo Liu
- Diabetes Research Group, School of Medicine, Division of Diabetes & Nutritional Sciences, King’s College London, London, United Kingdom
| | - Helena Barbosa-Sampaio
- Diabetes Research Group, School of Medicine, Division of Diabetes & Nutritional Sciences, King’s College London, London, United Kingdom
| | - Peter M. Jones
- Diabetes Research Group, School of Medicine, Division of Diabetes & Nutritional Sciences, King’s College London, London, United Kingdom
| | - Shanta J. Persaud
- Diabetes Research Group, School of Medicine, Division of Diabetes & Nutritional Sciences, King’s College London, London, United Kingdom
- * E-mail:
| | - Dany S. Muller
- Diabetes Research Group, School of Medicine, Division of Diabetes & Nutritional Sciences, King’s College London, London, United Kingdom
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23
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The role of fatty acid metabolism and lipotoxicity in pancreatic β-cell injury: Identification of potential therapeutic targets. Acta Pharm Sin B 2012. [DOI: 10.1016/j.apsb.2012.05.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Blandino-Rosano M, Chen AY, Scheys JO, Alejandro EU, Gould AP, Taranukha T, Elghazi L, Cras-Méneur C, Bernal-Mizrachi E. mTORC1 signaling and regulation of pancreatic β-cell mass. Cell Cycle 2012; 11:1892-902. [PMID: 22544327 DOI: 10.4161/cc.20036] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The capacity of β cells to expand in response to insulin resistance is a critical factor in the development of type 2 diabetes. Proliferation of β cells is a major component for these adaptive responses in animal models. The extracellular signals responsible for β-cell expansion include growth factors, such as insulin, and nutrients, such as glucose and amino acids. AKT activation is one of the important components linking growth signals to the regulation of β-cell expansion. Downstream of AKT, tuberous sclerosis complex 1 and 2 (TSC1/2) and mechanistic target of rapamycin complex 1 (mTORC1) signaling have emerged as prime candidates in this process, because they integrate signals from growth factors and nutrients. Recent studies demonstrate the importance of mTORC1 signaling in β cells. This review will discuss recent advances in the understanding of how this pathway regulates β-cell mass and present data on the role of TSC1 in modulation of β-cell mass. Herein, we also demonstrate that deletion of Tsc1 in pancreatic β cells results in improved glucose tolerance, hyperinsulinemia and expansion of β-cell mass that persists with aging.
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Affiliation(s)
- Manuel Blandino-Rosano
- Department of Internal Medicine; Division of Metabolism, Endocrinology and Diabetes, Brehm Center for Diabetes Research, University of Michigan Medical Center; Ann Arbor, MI, USA
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25
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Sartorius T, Lutz SZ, Hoene M, Waak J, Peter A, Weigert C, Rammensee HG, Kahle PJ, Häring HU, Hennige AM. Toll-like receptors 2 and 4 impair insulin-mediated brain activity by interleukin-6 and osteopontin and alter sleep architecture. FASEB J 2012; 26:1799-809. [PMID: 22278939 DOI: 10.1096/fj.11-191023] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Impaired insulin action in the brain represents an early step in the progression toward type 2 diabetes, and elevated levels of saturated free fatty acids are known to impair insulin action in prediabetic subjects. One potential mediator that links fatty acids to inflammation and insulin resistance is the Toll-like receptor (TLR) family. Therefore, C3H/HeJ/TLR2-KO (TLR2/4-deficient) mice were fed a high-fat diet (HFD), and insulin action in the brain as well as cortical and locomotor activity was analyzed by using telemetric implants. TLR2/4-deficient mice were protected from HFD-induced glucose intolerance and insulin resistance in the brain and displayed an improvement in cortical and locomotor activity that was not observed in C3H/HeJ mice. Sleep recordings revealed a 42% increase in rapid eye movement sleep in the deficient mice during daytime, and these mice spent 41% more time awake during the night period. Treatment of control mice with a neutralizing IL-6 antibody improved insulin action in the brain as well as cortical activity and diminished osteopontin protein to levels of the TLR2/4-deficient mice. Together, our data suggest that the lack of functional TLR2/4 protects mice from a fat-mediated impairment in insulin action, brain activity, locomotion, and sleep architecture by an IL-6/osteopontin-dependent mechanism.
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Affiliation(s)
- Tina Sartorius
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Disease, Nephrology and Clinical Chemistry, University of Tuebingen, Otfried-Mueller-Straße 10, D-72076 Tuebingen, Germany
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Demozay D, Tsunekawa S, Briaud I, Shah R, Rhodes CJ. Specific glucose-induced control of insulin receptor substrate-2 expression is mediated via Ca2+-dependent calcineurin/NFAT signaling in primary pancreatic islet β-cells. Diabetes 2011; 60:2892-902. [PMID: 21940781 PMCID: PMC3198104 DOI: 10.2337/db11-0341] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Insulin receptor substrate-2 (IRS-2) plays an essential role in pancreatic islet β-cells by promoting growth and survival. IRS-2 turnover is rapid in primary β-cells, but its expression is highly regulated at the transcriptional level, especially by glucose. The aim was to investigate the molecular mechanism on how glucose regulates IRS-2 gene expression in β-cells. RESEARCH DESIGN AND METHODS Rat islets were exposed to inhibitors or subjected to adenoviral vector-mediated gene manipulations and then to glucose-induced IRS-2 expression analyzed by real-time PCR and immunoblotting. Transcription factor nuclear factor of activated T cells (NFAT) interaction with IRS-2 promoter was analyzed by chromatin immunoprecipitation assay and glucose-induced NFAT translocation by immunohistochemistry. RESULTS Glucose-induced IRS-2 expression occurred in pancreatic islet β-cells in vivo but not in liver. Modulating rat islet β-cell Ca(2+) influx with nifedipine or depolarization demonstrated that glucose-induced IRS-2 gene expression was dependent on a rise in intracellular calcium concentration derived from extracellular sources. Calcineurin inhibitors (FK506, cyclosporin A, and a peptide calcineurin inhibitor [CAIN]) abolished glucose-induced IRS-2 mRNA and protein levels, whereas expression of a constitutively active calcineurin increased them. Specific inhibition of NFAT with the peptide inhibitor VIVIT prevented a glucose-induced IRS-2 transcription. NFATc1 translocation to the nucleus in response to glucose and association of NFATc1 to conserved NFAT binding sites in the IRS-2 promoter were demonstrated. CONCLUSIONS The mechanism behind glucose-induced transcriptional control of IRS-2 gene expression specific to the islet β-cell is mediated by the Ca(2+)/calcineurin/NFAT pathway. This insight into the IRS-2 regulation could provide novel therapeutic means in type 2 diabetes to maintain an adequate functional mass.
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Affiliation(s)
- Damien Demozay
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois
| | - Shin Tsunekawa
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois
| | | | - Ramila Shah
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois
| | - Christopher J. Rhodes
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois
- Corresponding author: Christopher J. Rhodes,
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Tsunekawa S, Demozay D, Briaud I, McCuaig J, Accili D, Stein R, Rhodes CJ. FoxO feedback control of basal IRS-2 expression in pancreatic β-cells is distinct from that in hepatocytes. Diabetes 2011; 60:2883-91. [PMID: 21933986 PMCID: PMC3198101 DOI: 10.2337/db11-0340] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Appropriate regulation of insulin receptor substrate 2 (IRS-2) expression in pancreatic β-cells is essential to adequately compensate for insulin resistance. In liver, basal IRS-2 expression is controlled via a temporal negative feedback of sterol regulatory element-binding protein 1 (SREBP-1) to antagonize transcription factors forkhead box class O (FoxO)1/FoxO3a at an insulin response element (IRE) on the IRS-2 promoter. The purpose of the study was to examine if a similar mechanism controlled IRS-2 expression in β-cells. RESEARCH DESIGN AND METHODS IRS-2 mRNA and protein expression, as well as IRS-2 gene promoter activity, were examined in isolated rat islets. Specific transcription factor association with the IRE on the IRS-2 promoter was examined by chromatin immunoprecipitation (ChIP) assay, and their nuclear translocation was examined by immunofluorescence. A direct in vivo effect of insulin on control of IRS-2 expression in liver and pancreatic islets was also investigated. RESULTS In IRS-2 promoter-reporter assays conducted in isolated islets, removal of the IRE decreased basal IRS-2 promoter activity in β-cells up to 80%. Activation of IRS signaling in isolated rat islets by insulin/IGF-I (used as an experimental in vitro tool) or downstream constitutive activation of protein kinase B (PKB) significantly decreased IRS-2 expression. In contrast, inhibition of phosphatidylinositol 3-kinase (PI3K) or PKB significantly increased IRS-2 levels in β-cells. ChIP assays indicated that transcription factors FoxO1 and FoxO3a associated with the IRE on the IRS-2 promoter in β-cells in a PI3K/PKB-dependent manner, whereas others, such as SREBP-1, the transcription factor binding to immunoglobulin heavy chain enhancer 3', and the aryl hydrocarbon receptor nuclear translocator (ARNT), did not. However, only FoxO3a, not FoxO1, was capable of driving IRS-2 promoter activity via the IRE in β-cells. In vivo studies showed insulin was able to suppress IRS-2 expression via activation of SREBP-1 in the liver, but this mechanism was not apparent in pancreatic islets from the same animal. CONCLUSIONS The molecular mechanism for feedback control of IRS signaling to decrease IRS-2 expression in liver and β-cells is quite distinct, with a predominant role played by FoxO3a in β-cells.
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Affiliation(s)
- Shin Tsunekawa
- Kovler Diabetes Center, Department of Medicine, University of Chicago, Chicago, Illinois
| | - Damien Demozay
- Kovler Diabetes Center, Department of Medicine, University of Chicago, Chicago, Illinois
| | | | - Jill McCuaig
- Kovler Diabetes Center, Department of Medicine, University of Chicago, Chicago, Illinois
| | - Domenico Accili
- Naomi Berrie Diabetes Center and Department of Medicine, Columbia University, New York City, New York
| | - Roland Stein
- Departments of Molecular Physiology and Biophysics and Cell Biology and Development, Vanderbilt University, Nashville, Tennessee
| | - Christopher J. Rhodes
- Kovler Diabetes Center, Department of Medicine, University of Chicago, Chicago, Illinois
- Corresponding author: Christopher J. Rhodes,
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Schultze SM, Jensen J, Hemmings BA, Tschopp O, Niessen M. Promiscuous affairs of PKB/AKT isoforms in metabolism. Arch Physiol Biochem 2011; 117:70-7. [PMID: 21214427 DOI: 10.3109/13813455.2010.539236] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The protein kinase B (PKB) family encompasses three isoforms; PKBα (AKT1), PKBβ (AKT2) and PKBγ (AKT3). PKBα and PKBβ but not PKBγ, are prominently expressed in classical insulin-sensitive tissues like liver, muscle and fat. Transgenic mice deficient for PKBα, PKBβ or PKBγ have been analysed to study the roles of PKB isoforms in metabolic regulation. Until recently, only loss of PKBβ was reported to result in metabolic disorders, especially insulin resistance, in humans and mice. However, a new study has shown that PKBα-deficient mice can show enhanced glucose tolerance accompanied by improved β-cell function and higher insulin sensitivity in adipocytes. These findings prompted us to review the relevant literature on the regulation of glucose metabolism by PKB isoforms in liver, skeletal muscle, adipocytes and pancreas.
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Affiliation(s)
- Simon M Schultze
- Endocrinology, Diabetology & Clinical Nutrition, University Hospital of Zurich, Switzerland
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29
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Dalle S, Ravier MA, Bertrand G. Emerging roles for β-arrestin-1 in the control of the pancreatic β-cell function and mass: New therapeutic strategies and consequences for drug screening. Cell Signal 2011; 23:522-8. [DOI: 10.1016/j.cellsig.2010.09.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 09/06/2010] [Indexed: 01/09/2023]
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30
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Choi SE, Lee YJ, Hwang GS, Chung JH, Lee SJ, Lee JH, Han SJ, Kim HJ, Lee KW, Kim Y, Jun HS, Kang Y. Supplement of TCA cycle intermediates protects against high glucose/palmitate-induced INS-1 beta cell death. Arch Biochem Biophys 2010; 505:231-41. [PMID: 20965146 DOI: 10.1016/j.abb.2010.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/12/2010] [Accepted: 10/14/2010] [Indexed: 01/22/2023]
Abstract
The aim of this study is to investigate the effect of mitochondrial metabolism on high glucose/palmitate (HG/PA)-induced INS-1 beta cell death. Long-term treatment of INS-1 cells with HG/PA impaired energy-producing metabolism accompanying with depletion of TCA cycle intermediates. Whereas an inhibitor of carnitine palmitoyl transferase 1 augmented HG/PA-induced INS-1 cell death, stimulators of fatty acid oxidation protected the cells against the HG/PA-induced death. Furthermore, whereas mitochondrial pyruvate carboxylase inhibitor phenylacetic acid augmented HG/PA-induced INS-1 cell death, supplementation of TCA cycle metabolites including leucine/glutamine, methyl succinate/α-ketoisocaproic acid, dimethyl malate, and valeric acid or treatment with a glutamate dehydrogenase activator, aminobicyclo-heptane-2-carboxylic acid (BCH), significantly protected the cells against the HG/PA-induced death. In particular, the mitochondrial tricarboxylate carrier inhibitor, benzene tricarboxylate (BTA), also showed a strong protective effect on the HG/PA-induced INS-1 cell death. Knockdown of glutamate dehydrogenase or tricarboxylate carrier augmented or reduced the HG/PA-induced INS-1 cell death, respectively. Both BCH and BTA restored HG/PA-induced reduction of energy metabolism as well as depletion of TCA intermediates. These data suggest that depletion of the TCA cycle intermediate pool and impaired energy-producing metabolism may play a role in HG/PA-induced cytotoxicity to beta cells and thus, HG/PA-induced beta cell glucolipotoxicity can be protected by nutritional or pharmacological maneuver enhancing anaplerosis or reducing cataplerosis.
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Affiliation(s)
- Sung-E Choi
- Institute for Medical Sciences, Ajou University School of Medicine, Suwon, Republic of Korea
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Soleimanpour SA, Crutchlow MF, Ferrari AM, Raum JC, Groff DN, Rankin MM, Liu C, De León DD, Naji A, Kushner JA, Stoffers DA. Calcineurin signaling regulates human islet {beta}-cell survival. J Biol Chem 2010; 285:40050-9. [PMID: 20943662 DOI: 10.1074/jbc.m110.154955] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The calcium-regulated phosphatase calcineurin intersects with both calcium and cAMP-mediated signaling pathways in the pancreatic β-cell. Pharmacologic calcineurin inhibition, necessary to prevent rejection in the setting of organ transplantation, is associated with post-transplant β-cell failure. We sought to determine the effect of calcineurin inhibition on β-cell replication and survival in rodents and in isolated human islets. Further, we assessed whether the GLP-1 receptor agonist and cAMP stimulus, exendin-4 (Ex-4), could rescue β-cell replication and survival following calcineurin inhibition. Following treatment with the calcineurin inhibitor tacrolimus, human β-cell apoptosis was significantly increased. Although we detected no human β-cell replication, tacrolimus significantly decreased rodent β-cell replication. Ex-4 nearly normalized both human β-cell survival and rodent β-cell replication when co-administered with tacrolimus. We found that tacrolimus decreased Akt phosphorylation, suggesting that calcineurin could regulate replication and survival via the PI3K/Akt pathway. We identify insulin receptor substrate-2 (Irs2), a known cAMP-responsive element-binding protein target and upstream regulator of the PI3K/Akt pathway, as a novel calcineurin target in β-cells. Irs2 mRNA and protein are decreased by calcineurin inhibition in both rodent and human islets. The effect of calcineurin on Irs2 expression is mediated at least in part through the nuclear factor of activated T-cells (NFAT), as NFAT occupied the Irs2 promoter in a calcineurin-sensitive manner. Ex-4 restored Irs2 expression in tacrolimus-treated rodent and human islets nearly to baseline. These findings reveal calcineurin as a regulator of human β-cell survival in part through regulation of Irs2, with implications for the pathogenesis and treatment of diabetes following organ transplantation.
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Affiliation(s)
- Scott A Soleimanpour
- Division of Endocrinology, Department of Medicine and the Institute for Diabetes, Obesity, and Metabolism, the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Gurevitch D, Boura-Halfon S, Isaac R, Shahaf G, Alberstein M, Ronen D, Lewis EC, Zick Y. Elimination of negative feedback control mechanisms along the insulin signaling pathway improves beta-cell function under stress. Diabetes 2010; 59:2188-97. [PMID: 20547979 PMCID: PMC2927941 DOI: 10.2337/db09-0890] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Cellular stress and proinflammatory cytokines induce phosphorylation of insulin receptor substrate (IRS) proteins at Ser sites that inhibit insulin and IGF-1 signaling. Here, we examined the role of Ser phosphorylation of IRS-2 in mediating the inhibitory effects of proinflammatory cytokines and cellular stress on beta-cell function. RESEARCH DESIGN AND METHODS Five potential inhibitory Ser sites located proximally to the P-Tyr binding domain of IRS-2 were mutated to Ala. These IRS-2 mutants, denoted IRS-2(5A), and their wild-type controls (IRS-2(WT)) were introduced into adenoviral constructs that were infected into Min6 cells or into cultured murine islets. RESULTS When expressed in cultured mouse islets, IRS-2(5A) was better than IRS-2(WT) in protecting beta-cells from apoptosis induced by a combination of IL-1beta, IFN-gamma, TNF-alpha, and Fas ligand. Cytokine-treated islets expressing IRS2(5A) secreted significantly more insulin in response to glucose than did islets expressing IRS-2(WT). This could be attributed to the higher transcription of Pdx1 in cytokine-treated islets that expressed IRS-2(5A). Accordingly, transplantation of 200 islets expressing IRS2(5A) into STZ-induced diabetic mice restored their ability to respond to a glucose load similar to naïve mice. In contrast, mice transplanted with islets expressing IRS2(WT) maintained sustained hyperglycemia 3 days after transplantation. CONCLUSIONS Elimination of a physiological negative feedback control mechanism along the insulin-signaling pathway that involves Ser/Thr phosphorylation of IRS-2 affords protection against the adverse effects of proinflammatory cytokines and improves beta-cell function under stress. Genetic approaches that promote IRS2(5A) expression in pancreatic beta-cells, therefore, could be considered a rational treatment against beta-cell failure after islet transplantation.
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Affiliation(s)
- Diana Gurevitch
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Sigalit Boura-Halfon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Roi Isaac
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Galit Shahaf
- Department of Clinical Biochemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Moti Alberstein
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Denise Ronen
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Eli C. Lewis
- Department of Clinical Biochemistry, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yehiel Zick
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
- Corresponding author: Yehiel Zick,
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Villarreal RS, Forneris ML, Uranga RM, Salvador GA, Ciuffo GM. Role of IRS-4 in PI3-K activation by insulin in HepG2 cells, modulation by Angiotensin II. ACTA ACUST UNITED AC 2010; 161:67-72. [PMID: 20079766 DOI: 10.1016/j.regpep.2009.12.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 12/04/2009] [Accepted: 12/30/2009] [Indexed: 11/16/2022]
Abstract
Insulin receptor substrate-4 (IRS-4) has a limited tissue expression and its modulation by tyr-phosphorylation is still controversial. We evaluated the participation of IRS-4 in the cross-talk between Angiotensin II (Ang II) and Insulin (Ins) receptors in HepG2 cells. Ins (10(-7)M) induced tyr-phosphorylation of IRS-4 (maximal at 5 min), an effect potentiated by Ang II AT(1) receptors. Phosphatydilinositol-3 kinase (PI3-K) inhibitors Wortmanin or LY294002 reduced Ang II effect on tyr-phosphorylation of IRS-4 to a level comparable to that of Ins alone. Physical association between IRS-4 substrate and PI3-K was demonstrated by co-immunoprecipitation. Recruitment of PI3-K by IRS-4 was induced by Ins (10(-7)M, 5 min) not by Ang II (10(-7)M) and this was inhibited by Wortmanin and LY294002. Ang II did not modify either the association or activation of PI3-K in immunocomplexes. The present data provide novel evidence of IRS-4 phosphorylation mediated by Ins, an effect modulated by Ang II. We report also Ins-induced PI3-K activation mediated by IRS-4. Our findings suggest a role for IRS-4 as a docking protein in the Ins signaling pathway that involves PI3-K association and activation. The present data suggest a possible participation of IRS-4 in cell proliferation Ins-induced.
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Affiliation(s)
- Rodrigo Sebastián Villarreal
- Instituto Multidisciplinario de Investigaciones Biológicas (IMIBIO-SL, CONICET), Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Ejército de los Andes 950, 5700 San Luis, Argentina
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Venieratos PD, Drossopoulou GI, Kapodistria KD, Tsilibary EC, Kitsiou PV. High glucose induces suppression of insulin signalling and apoptosis via upregulation of endogenous IL-1beta and suppressor of cytokine signalling-1 in mouse pancreatic beta cells. Cell Signal 2010; 22:791-800. [PMID: 20067833 DOI: 10.1016/j.cellsig.2010.01.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 12/22/2009] [Accepted: 01/05/2010] [Indexed: 12/31/2022]
Abstract
Chronic hyperglycemia and inflammatory cytokines disrupt and/or attenuate signal transduction pathways that promote normal beta-cell survival, leading to the destruction of endocrine pancreas in type 2 diabetes. There is convincing evidence that autocrine insulin signalling exerts protective anti-apoptotic effects on beta cells. Suppressors of cytokine signalling (SOCS) were induced by several cytokines and inhibit insulin-initiated signal transduction. The aim of this study was to investigate whether high glucose can influence endogenous interleukin-1beta (IL-1beta) and SOCS expression thus affecting insulin signalling and survival in insulin-producing mouse pancreatic beta cells (betaTC-6). Results showed that prolonged exposure of betaTC-6 cells to increased glucose concentrations resulted in significant inhibition of insulin-induced tyrosine phosphorylation of the insulin receptor (IR), and insulin receptor substrate-2 (IRS-2) as well as PI3-kinase activation. These changes were accompanied by impaired activation of the anti-apoptotic signalling protein Akt and annulment of Akt-mediated suppression of the Forkhead family of transcription factors (FoxO) activation. Glucose-induced attenuation of IRS-2/Akt-mediated signalling was associated with increased IL-1beta expression. Enhanced endogenous IL-1beta specifically induced mRNA and protein expression of SOCS-1 in betaTC-6 cells. Inhibition of SOCS-1 expression by SOCS-1-specific small interfering RNA restored IRS-2/PI3K-mediated Akt phosphorylation suppressed by high glucose. The upregulation of endogenous cytokine signalling and FoxO activation were accompanied by enhanced caspase-3 activation and increased susceptibility of cells to apoptosis. These results indicated that glucose-induced endogenous IL-1beta expression increased betaTC-6 cells apoptosis by inhibiting, at least in part, IRS-2/Akt-mediated signalling through SOCS-1 upregulation.
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Affiliation(s)
- Panagiotis D Venieratos
- Institute of Biology, National Centre for Scientific Research "Demokritos", Athens, Attiki, Greece
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35
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Differential effects of protein kinase B/Akt isoforms on glucose homeostasis and islet mass. Mol Cell Biol 2009; 30:601-12. [PMID: 19933838 DOI: 10.1128/mcb.00719-09] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Protein kinase B (PKB)/Akt is considered to be a key target downstream of insulin receptor substrate 2 (IRS2) in the regulation of beta-cell mass. However, while deficiency of IRS2 in mice results in diabetes with insulin resistance and severe failure of beta-cell mass and function, only loss of the PKBbeta isoform leads to a mild metabolic phenotype with insulin resistance. Other isoforms were reported not to be required for metabolic regulation. To clarify the roles of the three PKB isoforms in the regulation of islet mass and glucose homeostasis, we assessed the metabolic and pancreatic phenotypes of Pkbalpha, Pkbbeta, and Pkbgamma-deficient mice. Our study uncovered a novel role for PKBalpha in the regulation of glucose homeostasis, whereas it confirmed that Pkbbeta(-/)(-) mice are insulin resistant with compensatory increase of islet mass. Pkbalpha(-/)(-) mice displayed an opposite phenotype with improved insulin sensitivity, lower blood glucose, and higher serum glucagon concentrations. Pkbgamma(-/)(-) mice did not show metabolic abnormalities. Additionally, our signaling analyses revealed that PKBalpha, but not PKBbeta or PKBgamma, is specifically activated by overexpression of IRS2 in beta-cells and is required for IRS2 action in the islets.
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36
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Kim B, Feldman EL. Insulin receptor substrate (IRS)-2, not IRS-1, protects human neuroblastoma cells against apoptosis. Apoptosis 2009; 14:665-73. [PMID: 19259821 DOI: 10.1007/s10495-009-0331-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Insulin receptor substrates (IRS)-1 and -2 are major substrates of insulin and type I insulin-like growth factor (IGF-I) receptor (IGF-IR) signaling. In this study, SH-EP human neuroblastoma cells are used as a model system to examine the differential roles of IRS-1 and IRS-2 on glucose-mediated apoptosis. In the presence of high glucose, IRS-1 underwent caspase-mediated degradation, followed by focal adhesion kinase (FAK) and Akt degradation and apoptosis. IRS-2 expression blocked all these changes whereas IRS-1 overexpression had no effect. In parallel, IRS-2, but not IRS-1, overexpression enhanced IGF-I-mediated Akt activation without affecting extracellular regulated kinase signaling. While IRS-1 was readily degraded by caspases, hyperglycemia-mediated IRS-2 degradation was unaffected by caspase inhibitors but blocked by proteasome and calpain inhibitors. Our data suggest that the differential degradation of IRS-1 and IRS-2 contributes to their distinct modes of action and the increased neuroprotective effects of IRS-2 in this report are due, in part, to its resistance to caspase-mediated degradation.
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Affiliation(s)
- Bhumsoo Kim
- Department of Neurology, University of Michigan, 5371 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109-2200, USA.
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37
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Vodenik B, Rovira J, Campistol JM. Mammalian target of rapamycin and diabetes: what does the current evidence tell us? Transplant Proc 2009; 41:S31-8. [PMID: 19651294 DOI: 10.1016/j.transproceed.2009.06.159] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
New-onset diabetes mellitus after transplantation (NODAT) is a serious complication in organ transplantation; not only does it enhance the risk of graft dysfunction, it also increases cardiovascular morbidity and mortality. The mammalian target of rapamycin (mTOR) is regulated independently by insulin, amino acids, and energy sufficiency. It integrates signal from growth factors, hormones, nutrients, and cellular energy levels to regulate protein translation and cell growth, proliferation, and survival. In addition, mTOR generates an inhibitory feedback loop on insulin receptor substrate (IRS) proteins. Therefore, it was suggested that mTOR might link nutrient excess with both obesity and insulin resistance. In this review, we summarize the role of mTOR and its inhibitor sirolimus (SRL) on chronic hyperglycemia and insulin resistance in beta cells, adipose tissue, liver, and muscle. We further hypothesize, based on data from the literature and generated in our laboratory, that SRL could counteract the development of NODAT in stable glucose homeostasis due to its positive effects on insulin-stimulated glucose uptake, whereas in conditions that require an adaptive beta cell proliferation (such as pregnancy and weight increase), the administration of SRL might have effects that would promote the development of NODAT. Therefore, it seems crucial for patient outcome to consider these potentially contrasting effects of SRL.
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Affiliation(s)
- B Vodenik
- Department of Nephrology and Renal Transplantation, Laboratori Experimental de Nefrologia I Trasplantament (LENIT), Hospital Clinic i Provincial de Barcelona, Barcelona, Spain
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38
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Association analysis of v-AKT murine thymoma viral oncogene homolog 1 (AKT1) polymorphisms and type 2 diabetes mellitus in the Korean population. Genes Genomics 2009. [DOI: 10.1007/bf03191140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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39
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40
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Choi SE, Lee SM, Lee YJ, Li LJ, Lee SJ, Lee JH, Kim Y, Jun HS, Lee KW, Kang Y. Protective role of autophagy in palmitate-induced INS-1 beta-cell death. Endocrinology 2009; 150:126-34. [PMID: 18772242 DOI: 10.1210/en.2008-0483] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Autophagy, a vacuolar degradative pathway, constitutes a stress adaptation that avoids cell death or elicits the alternative cell-death pathway. This study was undertaken to determine whether autophagy is activated in palmitate (PA)-treated beta-cells and, if activated, what the role of autophagy is in the PA-induced beta-cell death. The enhanced formation of autophagosomes and autolysosomes was observed by exposure of INS-1 beta-cells to 400 microm PA in the presence of 25 mm glucose for 12 h. The formation of green fluorescent protein-LC3-labeled structures (green fluorescent protein-LC3 dots), with the conversion from LC3-I to LC3-II, was also distinct in the PA-treated cells. The phospho-mammalian target of rapamycin level, a typical signal pathway that inhibits activation of autophagy, was gradually decreased by PA treatment. Blockage of the mammalian target of rapamycin signaling pathway by treatment with rapamycin augmented the formation of autophagosomes but reduced PA-induced INS-1 cell death. In contrast, reduction of autophagosome formation by knocking down the ATG5, inhibition of fusion between autophagosome and lysosome by treatment with bafilomycin A1, or inhibition of proteolytic degradation by treatment with E64d/pepstatin A, significantly augmented PA-induced INS-1 cell death. These findings showed that the autophagy system could be activated in PA-treated INS-1 beta-cells, and suggested that the induction of autophagy might play an adaptive and protective role in PA-induced cell death.
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Affiliation(s)
- Sung-E Choi
- Institute for Medical Science, Ajou University School of Medicine, Wonchon-dong san5, Yongtong-gu, Suwon, Gyeonggi-do 442-749, Republic of Korea
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41
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Takamoto I, Terauchi Y, Kubota N, Ohsugi M, Ueki K, Kadowaki T. Crucial role of insulin receptor substrate-2 in compensatory beta-cell hyperplasia in response to high fat diet-induced insulin resistance. Diabetes Obes Metab 2008; 10 Suppl 4:147-56. [PMID: 18834442 DOI: 10.1111/j.1463-1326.2008.00951.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In type 2 diabetes, there is a defect in the regulation of functional beta-cell mass to overcome high-fat (HF) diet-induced insulin resistance. Many signals and pathways have been implicated in beta-cell function, proliferation and apoptosis. The co-ordinated regulation of functional beta-cell mass by insulin signalling and glucose metabolism under HF diet-induced insulin-resistant conditions is discussed in this article. Insulin receptor substrate (IRS)-2 is one of the two major substrates for the insulin signalling. Interestingly, IRS-2 is involved in the regulation of beta-cell proliferation, as has been demonstrated using knockout mice models. On the other hand, in an animal model for human type 2 diabetes with impaired insulin secretion because of insufficiency of glucose metabolism, decreased beta-cell proliferation was observed in mice with beta-cell-specific glucokinase haploinsufficiency (Gck(+/) (-)) fed a HF diet without upregulation of IRS-2 in beta-cells, which was reversed by overexpression of IRS-2 in beta-cells. As to the mechanism underlying the upregulation of IRS-2 in beta-cells, glucose metabolism plays an important role independently of insulin, and phosphorylation of cAMP response element-binding protein triggered by calcium-dependent signalling is the critical pathway. Downstream from insulin signalling via IRS-2 in beta-cells, a reduction in FoxO1 nuclear exclusion contributes to the insufficient proliferative response of beta-cells to insulin resistance. These findings suggest that IRS-2 is critical for beta-cell hyperplasia in response to HF diet-induced insulin resistance.
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Affiliation(s)
- I Takamoto
- Department of Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Japan
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42
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Choi SE, Lee YJ, Jang HJ, Lee KW, Kim YS, Jun HS, Kang SS, Chun J, Kang Y. A chemical chaperone 4-PBA ameliorates palmitate-induced inhibition of glucose-stimulated insulin secretion (GSIS). Arch Biochem Biophys 2008; 475:109-14. [DOI: 10.1016/j.abb.2008.04.015] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 04/07/2008] [Accepted: 04/13/2008] [Indexed: 10/22/2022]
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Disruption of Tsc2 in pancreatic beta cells induces beta cell mass expansion and improved glucose tolerance in a TORC1-dependent manner. Proc Natl Acad Sci U S A 2008; 105:9250-5. [PMID: 18587048 DOI: 10.1073/pnas.0803047105] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Regulation of pancreatic beta cell mass and function is a major determinant for the development of diabetes. Growth factors and nutrients are important regulators of beta cell mass and function. The signaling pathways by which these growth signals modulate these processes have not been completely elucidated. Tsc2 is an attractive candidate to modulate these processes, because it is a converging point for growth factor and nutrient signals. In these experiments, we generated mice with conditional deletion of Tsc2 in beta cells (betaTsc2(-/-)). These mice exhibited decreased glucose levels and hyperinsulinemia in the fasting and fed state. Improved glucose tolerance in these mice was observed as early as 4 weeks of age and was still present in 52-week-old mice. Deletion of Tsc2 in beta cells induced expansion of beta cell mass by increased proliferation and cell size. Rapamycin treatment reversed the metabolic changes in betaTsc2(-/-) mice by induction of insulin resistance and reduction of beta cell mass. The reduction of beta cell mass in betaTsc2(-/-) mice by inhibition of the mTOR/Raptor (TORC1) complex with rapamycin treatment suggests that TORC1 mediates proliferative and growth signals induced by deletion of Tsc2 in beta cells. These studies uncover a critical role for the Tsc2/mTOR pathway in regulation of beta cell mass and carbohydrate metabolism in vivo.
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44
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Bouzakri K, Ribaux P, Tomas A, Parnaud G, Rickenbach K, Halban PA. Rab GTPase-activating protein AS160 is a major downstream effector of protein kinase B/Akt signaling in pancreatic beta-cells. Diabetes 2008; 57:1195-204. [PMID: 18276765 DOI: 10.2337/db07-1469] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Protein kinase B/Akt plays a central role in beta-cells, but little is known regarding downstream Akt substrates in these cells. Recently, Rab GTPase-activating protein AS160, a substrate of Akt, was shown to be involved in insulin modulation of GLUT4 trafficking in skeletal muscle and adipose tissue. The aim of this study was to investigate the expression and potential role of AS160 in beta-cells. RESEARCH DESIGN AND METHODS AS160 mRNA expression was measured in mouse and human islets and fluorescence-activated cell sorted beta-cells and compared in islets from control subjects versus individuals with type 2 diabetes. For knockdown experiments, transformed mouse insulin-secreting MIN6B1 cells were transfected with pSUPER-GFP plasmid encoding a small hairpin RNA against insulin receptor substrate (IRS)-2, AS160, or a negative control. Primary mouse islet cells were transfected with AS160 small interfering RNA. RESULTS AS160 was expressed in human and mouse pancreatic beta-cells and phosphorylated after glucose stimulation. AS160 mRNA expression was downregulated in pancreatic islets from individuals with type 2 diabetes. In MIN6B1 cells, glucose induced phosphorylation of Akt and AS160, and this was mediated by insulin receptor/IRS-2/phosphatidylinositol 3-kinase independently of changes in cytosolic Ca(2+). Knockdown of AS160 resulted in increased basal insulin secretion, whereas glucose-stimulated insulin release was abolished. Furthermore, beta-cells with decreased AS160 showed increased apoptosis and loss of glucose-induced proliferation. CONCLUSIONS This study shows for the first time that AS160, previously recognized as a key player in insulin signaling in skeletal muscle and adipose tissue, is also a major effector of protein kinase B/Akt signaling in the beta-cell.
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Affiliation(s)
- Karim Bouzakri
- University Medical Center, Department of Genetic Medicine and Development, 1 Rue Michel-Servet, CH-1211 Geneva 4, Switzerland.
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45
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Lai E, Bikopoulos G, Wheeler MB, Rozakis-Adcock M, Volchuk A. Differential activation of ER stress and apoptosis in response to chronically elevated free fatty acids in pancreatic beta-cells. Am J Physiol Endocrinol Metab 2008; 294:E540-50. [PMID: 18198352 DOI: 10.1152/ajpendo.00478.2007] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Chronic exposure to elevated saturated free fatty acid (FFA) levels has been shown to induce endoplasmic reticulum (ER) stress that may contribute to promoting pancreatic beta-cell apoptosis. Here, we compared the effects of FFAs on apoptosis and ER stress in human islets and two pancreatic beta-cell lines, rat INS-1 and mouse MIN6 cells. Isolated human islets cultured in vitro underwent apoptosis, and markers of ER stress pathways were elevated by chronic palmitate exposure. Palmitate also induced apoptosis in MIN6 and INS-1 cells, although the former were more resistant to both apoptosis and ER stress. MIN6 cells were found to express significantly higher levels of ER chaperone proteins than INS-1 cells, which likely accounts for the ER stress resistance. We attempted to determine the relative contribution that ER stress plays in palmitate-induced beta-cell apoptosis. Although overexpressing GRP78 in INS-1 cells partially reduced susceptibility to thapsigargin, this failed to reduce palmitate-induced ER stress or apoptosis. In INS-1 cells, palmitate induced apoptosis at concentrations that did not result in significant ER stress. Finally, MIN6 cells depleted of GRP78 were more susceptible to tunicamycin-induced apoptosis but not to palmitate-induced apoptosis compared with control cells. These results suggest that ER stress is likely not the main mechanism involved in palmitate-induced apoptosis in beta-cell lines. Human islets and MIN6 cells were found to express high levels of stearoyl-CoA desaturase-1 compared with INS-1 cells, which may account for the decreased susceptibility of these cells to the cytotoxic effects of palmitate.
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Affiliation(s)
- Elida Lai
- Division of Cell and Molecular Biology, Toronto General Research Institute, University Health Network, 101 College Street, TMOT 10-707, Toronto, ON, Canada, M5G1L7
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Choi SE, Kim HE, Shin HC, Jang HJ, Lee KW, Kim Y, Kang SS, Chun J, Kang Y. Involvement of Ca2+-mediated apoptotic signals in palmitate-induced MIN6N8a beta cell death. Mol Cell Endocrinol 2007; 272:50-62. [PMID: 17507155 DOI: 10.1016/j.mce.2007.04.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/06/2007] [Accepted: 04/19/2007] [Indexed: 01/09/2023]
Abstract
The extracellular Ca(2+) chelator EGTA and L-type Ca(2+) channel blockers, such as, nifedipine and nimodipine were found to have a protective effect on palmitate-induced MIN6N8a beta cell apoptosis, whereas the Ca(2+) channel opener, Bay K8644, enhanced the apoptotic process. Moreover, the phospho-form of Bad, in conjunction with phospho-Akt, was reduced in response to palmitate and the palmitate-induced dephosphorylations of Akt and Bad were dependent on Ca(2+) influx. The transient expression of catalytically active Akt prevented MIN6N8a cells from palmitate-induced apoptosis. Deltamethrin, an inhibitor of Ca(2+)-activated phosphatase, delayed Akt and Bad dephosphorylations, and then protected MIN6N8a cells from palmitate-induced apoptosis. On the other hand, palmitate was found to induce CHOP, an apoptotic transcription factor in response to ER stress, and this induction was enhanced by Ca(2+) influx. Our studies suggested that Ca(2+) influx and subsequent Ca(2+)-mediated apoptotic signals are involved in palmitate-induced beta cell death.
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Affiliation(s)
- Sung-E Choi
- Institute for Medical Science, Ajou University School of Medicine, 442-749 Suwon, Republic of Korea
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47
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Denley A, Carroll JM, Brierley GV, Cosgrove L, Wallace J, Forbes B, Roberts CT. Differential activation of insulin receptor substrates 1 and 2 by insulin-like growth factor-activated insulin receptors. Mol Cell Biol 2007; 27:3569-77. [PMID: 17325037 PMCID: PMC1899985 DOI: 10.1128/mcb.01447-06] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The insulin-like growth factors (insulin-like growth factor I [IGF-I] and IGF-II) exert important effects on growth, development, and differentiation through the IGF-I receptor (IGF-IR) transmembrane tyrosine kinase. The insulin receptor (IR) is structurally related to the IGF-IR, and at high concentrations, the IGFs can also activate the IR, in spite of their generally low affinity for the latter. Two mechanisms that facilitate cross talk between the IGF ligands and the IR at physiological concentrations have been described. The first of these is the existence of an alternatively spliced IR variant that exhibits high affinity for IGF-II as well as for insulin. A second phenomenon is the ability of hybrid receptors comprised of IGF-IR and IR hemireceptors to bind IGFs, but not insulin. To date, however, direct activation of an IR holoreceptor by IGF-I at physiological levels has not been demonstrated. We have now found that IGF-I can function through both splice variants of the IR, in spite of low affinity, to specifically activate IRS-2 to levels similar to those seen with equivalent concentrations of insulin or IGF-II. The specific activation of IRS-2 by IGF-I through the IR does not result in activation of the extracellular signal-regulated kinase pathway but does induce delayed low-level activation of the phosphatidylinositol 3-kinase pathway and biological effects such as enhanced cell viability and protection from apoptosis. These findings suggest that IGF-I can function directly through the IR and that the observed effects of IGF-I on insulin sensitivity may be the result of direct facilitation of insulin action by IGF-I costimulation of the IR in insulin target tissues.
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Affiliation(s)
- Adam Denley
- Oregon National Primate Research Center, L584, 505 NW 185th Ave., Beaverton, OR 97006-3448, USA
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Fernández E, Martín MA, Fajardo S, Escrivá F, Alvarez C. Increased IRS-2 content and activation of IGF-I pathway contribute to enhance beta-cell mass in fetuses from undernourished pregnant rats. Am J Physiol Endocrinol Metab 2007; 292:E187-95. [PMID: 16912057 DOI: 10.1152/ajpendo.00283.2006] [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: 12/31/2022]
Abstract
We have previously shown that fetuses from undernourished (U) pregnant rats exhibited an increased beta-cell mass probably related to an enhanced IGF-I replicative response. Because IGF-I signaling pathways have been implicated in regulating beta-cell growth, we investigated in this study the IGF-I transduction system in U fetuses. To this end, an in vitro model of primary fetal islets was developed to characterize glucose/IGF-I-mediated signaling that specially influences beta-cell proliferation. We found that U fetal islets showed a greater replicative response to glucose and IGF-I than controls. Furthermore, insulin receptor substrate (IRS)-2 protein and its association with p85 were also increased. In the complete absence of IGF-I or stimulatory glucose, U islets presented an increased basal phosphorylation of downstream signals of the phosphatidylinositol 3-kinase (PI3K) pathway such as PKB, glycogen synthase kinase (GSK)3alpha/beta, PKCzeta, and mammalian target of rapamycin (mTOR). Similarly, phosphorylation of these proteins (except GSK3alpha/beta) by glucose and IGF-I was augmented even though total protein content remained unchanged. Downstream of PKB, direct glucose activation of mTOR was increased as well. In contrast, ERK1/2 phosphorylation was unaffected by undernutrition, but ERK activation seemed to be required to induce a higher proliferative response in U islets. In conclusion, we have demonstrated that fetal U islets show increased IRS-2 content and an enhancement in both basal and glucose/IGF-I activations of the IRS-2/PI3K/PKB pathway. These molecular changes may be responsible for the greater glucose/IGF-I islet replication and contribute to the increased beta-cell mass found in these fetuses.
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Affiliation(s)
- Elisa Fernández
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense, Ciudad Universitaria, 28040 Madrid, Spain
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Ranta F, Avram D, Berchtold S, Düfer M, Drews G, Lang F, Ullrich S. Dexamethasone induces cell death in insulin-secreting cells, an effect reversed by exendin-4. Diabetes 2006; 55:1380-90. [PMID: 16644695 DOI: 10.2337/db05-1220] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Glucocorticoid excess induces hyperglycemia, which may result in diabetes. The present experiments explored whether glucocorticoids trigger apoptosis in insulin-secreting cells. Treatment of mouse beta-cells or INS-1 cells with the glucocorticoid dexamethasone (0.1 micromol/l) over 4 days in cell culture increased the number of fractionated nuclei from 2 to 7 and 14%, respectively, an effect that was reversed by the glucocorticoid receptor antagonist RU486 (1 micromol/l). In INS-1 cells, dexamethasone increased the number of transferase-mediated dUTP nick-end labeling-staining positive cells, caspase-3 activity, and poly-(ADP-) ribose polymerase protein cleavage; decreased Bcl-2 transcript and protein abundance; dephosphorylated the proapoptotic protein of the Bcl-2 family (BAD) at serine155; and depolarized mitochondria. Dexamethasone increased PP-2B (calcineurin) activity, an effect abrogated by FK506. FK506 (0.1 micromol/l) and another calcineurin inhibitor, deltamethrin (1 micromol/l), attenuated dexamethasone-induced cell death. The stable glucagon-like peptide 1 analog, exendin-4 (10 nmol/l), inhibited dexamethasone-induced apoptosis in mouse beta-cells and INS-1 cells. The protective effect of exendin-4 was mimicked by forskolin (10 micromol/l) but not mimicked by guanine nucleotide exchange factor with the specific agonist 8CPT-Me-cAMP (50 micromol/l). Exendin-4 did not protect against cell death in the presence of cAMP-dependent protein kinase (PKA) inhibition by H89 (10 micromol/l) or KT5720 (5 micromol/l). In conclusion, glucocorticoid-induced apoptosis in insulin-secreting cells is accompanied by a downregulation of Bcl-2, activation of calcineurin with subsequent dephosphorylation of BAD, and mitochondrial depolarization. Exendin-4 protects against glucocorticoid-induced apoptosis, an effect mimicked by forskolin and reversed by PKA inhibitors.
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Affiliation(s)
- Felicia Ranta
- Institut für Physiologie, University of Tübingen, Gmelinstrasse 5, D-72076 Tübingen, Germany
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Lingohr MK, Briaud I, Dickson LM, McCuaig JF, Alárcon C, Wicksteed BL, Rhodes CJ. Specific regulation of IRS-2 expression by glucose in rat primary pancreatic islet beta-cells. J Biol Chem 2006; 281:15884-92. [PMID: 16574657 DOI: 10.1074/jbc.m600356200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Insulin receptor substrate 2 (IRS-2) plays a critical role in pancreatic beta-cells. Increased IRS-2 expression promotes beta-cell growth and survival, whereas decreased IRS-2 levels lead to apoptosis. It was found that IRS-2 turnover in rat islet beta-cells was rapid, with mRNA and protein half-lives of approximately 90 min and approximately 2 h, respectively. However, this was countered by specific glucose-regulated IRS-2 expression mediated at the transcriptional level. Glucose (> or = 6 mM) increased IRS-2 mRNA and protein levels in a dose-dependent manner, reaching a maximum 4-fold increase in IRS-2 mRNA and a 5-6-fold increase in IRS-2 protein levels at > or = 12 mM glucose (p < or = 0.01). Glucose (15 mM) regulation of islet beta-cell IRS-2 gene expression was rapid, with a significant increase in IRS-2 mRNA levels within 2 h that reached a maximum 4-fold increase by 4 h. IRS-2 protein expression in beta-cells followed that of IRS-2 mRNA. Glucose metabolism was necessary for increased IRS-2 expression in beta-cells. Moreover, inhibition of a glucose-induced rise in islet beta-cell cytosolic [Ca2+]i prevented an increase in IRS-2 expression, indicating this was Ca2+-dependent. The glucose-induced rise in IRS-2 levels correlated with increased IRS-2 tyrosine phosphorylation and downstream activation of protein kinase B. These data indicate that fluctuations of glucose in the normal physiological range (5-15 mM) promote beta-cell survival via regulation of IRS-2 expression and a subsequent parallel protein kinase B activation. Given that the onset of type-2 diabetes is marked by loss of beta-cells, these data further the idea that controlled IRS-2 expression in beta-cells could be a therapeutic means to promote beta-cell survival and delay the onset of the disease.
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Affiliation(s)
- Melissa K Lingohr
- The Pacific Northwest Research Institute, Seattle, Washington 98122, USA
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