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Yan W, Guo T, Liu N, Cui X, Wei X, Sun Y, Hu H, Chen L. Erythropoietin ameliorates cognitive deficits by improving hippocampal and synaptic damage in streptozotocin-induced diabetic mice. Cell Signal 2023; 106:110614. [PMID: 36739954 DOI: 10.1016/j.cellsig.2023.110614] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/05/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023]
Abstract
Recent studies have shown that erythropoietin (EPO) is an effective neuroprotective and neurotrophic agent for neurological disorders, such as traumatic brain injury and Alzheimer's disease. However, the effectiveness of EPO administration against diabetic cognitive impairments has rarely been examined. In this study, we investigated the effects of EPO on streptozotocin (STZ)-induced male C57BL/6 J mice. Then, we sought to clarify the mechanisms of EPO-mediated neuroprotection in high-glucose (HG)-stimulated HT22 cells. In vivo, we found that STZ-induced diabetic mice showed impaired spatial learning and memory, which was alleviated by EPO treatment. EPO also significantly lowered elevated fasting blood glucose levels, improved pancreatic and hippocampal damage, and restored oxidative stress in the STZ-induced diabetic mice. In vitro, EPO markedly increased cell viability, restrained the expression of pro-apoptotic Bax, enhanced the expression of pro-caspase 3, anti-apoptotic Bcl-2, brain-derived neurotrophic factor (BDNF) and postsynaptic density 95 (PSD-95), and attenuated the upregulation of N-methyl-d-aspartic acid (NMDA) receptor subunits NR1, NR2A and NR2B in HG-induced HT22 cells. The protective effects of EPO was obviously abolished by treatment with an NMDA receptor agonist. Our findings revealed that EPO impedes hippocampal and synaptic damage and neuronal apoptosis by regulating BDNF and PSD-95 expression through NMDA receptors, thereby ameliorating cognitive impairments in mice with T1DM.
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Affiliation(s)
- Wenhui Yan
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Institute of Cardiovascular Sciences, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, Shaanxi 710061, China
| | - Tingli Guo
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China
| | - Na Liu
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China
| | - Xin Cui
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China
| | - Xiaotong Wei
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China
| | - Yuzhuo Sun
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China
| | - Hao Hu
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Institute of Cardiovascular Sciences, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, Shaanxi 710061, China
| | - Lina Chen
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Institute of Cardiovascular Sciences, Translational Medicine Institute, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, Shaanxi 710061, China; International Obesity and Metabolic Disease Research Center (IIOMC), Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China.
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Camaya I, Donnelly S, O'Brien B. Targeting the PI3K/Akt signaling pathway in pancreatic β-cells to enhance their survival and function: An emerging therapeutic strategy for type 1 diabetes. J Diabetes 2022; 14:247-260. [PMID: 35191175 PMCID: PMC9060113 DOI: 10.1111/1753-0407.13252] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 01/11/2022] [Indexed: 12/16/2022] Open
Abstract
Type 1 diabetes (T1D) is an autoimmune disease caused by the destruction of the insulin-producing β-cells within the pancreas. Islet transplantation represents one cure; however, during islet preparation and post transplantation significant amounts of β-cell death occur. Therefore, prevention and cure of T1D is dependent upon the preservation of β-cell function and the prevention of β-cell death. Phosphoinositide 3-kinase (PI3K)/Akt signaling represents a promising therapeutic target for T1D due to its pronounced effects on cellular survival, proliferation, and metabolism. A growing amount of evidence indicates that PI3K/Akt signaling is a critical determinant of β-cell mass and function. Modulation of the PI3K/Akt pathway, directly (via the use of highly specific protein and peptide-based biologics, excretory/secretory products of parasitic worms, and complex constituents of plant extracts) or indirectly (through microRNA interactions) can regulate the β-cell processes to ultimately determine the fate of β-cell mass. An important consideration is the identification of the specific PI3K/Akt pathway modulators that enhance β-cell function and prevent β-cell death without inducing excessive β-cell proliferation, which may carry carcinogenic side effects. Among potential PI3K/Akt pathway agonists, we have identified a novel parasite-derived protein, termed FhHDM-1 (Fasciola hepatica helminth defense molecule 1), which efficiently stimulates the PI3K/Akt pathway in β-cells to enhance function and prevent death without concomitantly inducing proliferation unlike several other identified stimulators of PI3K/Akt signaling . As such, FhHDM-1 will inform the design of biologics aimed at targeting the PI3K/Akt pathway to prevent/ameliorate not only T1D but also T2D, which is now widely recognized as an inflammatory disease characterized by β-cell dysfunction and death. This review will explore the modulation of the PI3K/Akt signaling pathway as a novel strategy to enhance β-cell function and survival.
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Affiliation(s)
- Inah Camaya
- School of Life Sciences, Faculty of ScienceThe University of Technology SydneyUltimoNew South WalesAustralia
| | - Sheila Donnelly
- School of Life Sciences, Faculty of ScienceThe University of Technology SydneyUltimoNew South WalesAustralia
| | - Bronwyn O'Brien
- School of Life Sciences, Faculty of ScienceThe University of Technology SydneyUltimoNew South WalesAustralia
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Camaya I, Mok TY, Lund M, To J, Braidy N, Robinson MW, Santos J, O'Brien B, Donnelly S. The parasite-derived peptide FhHDM-1 activates the PI3K/Akt pathway to prevent cytokine-induced apoptosis of β-cells. J Mol Med (Berl) 2021; 99:1605-1621. [PMID: 34374810 DOI: 10.1007/s00109-021-02122-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/13/2021] [Accepted: 07/27/2021] [Indexed: 12/31/2022]
Abstract
Type 1 diabetes (T1D) is an autoimmune disease characterised by the destruction of the insulin-producing beta (β)-cells within the pancreatic islets. We have previously identified a novel parasite-derived molecule, termed Fasciola hepatica helminth defence molecule 1 (FhHDM-1), that prevents T1D development in non-obese diabetic (NOD) mice. In this study, proteomic analyses of pancreas tissue from NOD mice suggested that FhHDM-1 activated the PI3K/Akt signalling pathway, which is associated with β-cell metabolism, survival and proliferation. Consistent with this finding, FhHDM-1 preserved β-cell mass in NOD mice. Examination of the biodistribution of FhHDM-1 after intraperitoneal administration in NOD mice revealed that the parasite peptide localised to the pancreas, suggesting that it exerted a direct effect on the survival/function of β-cells. This was confirmed in vitro, as the interaction of FhHDM-1 with the NOD-derived β-cell line, NIT-1, resulted in increased levels of phosphorylated Akt, increased NADH and NADPH and reduced activity of the NAD-dependent DNA nick sensor, poly(ADP-ribose) polymerase (PARP-1). As a consequence, β-cell survival was enhanced and apoptosis was prevented in the presence of the pro-inflammatory cytokines that destroy β-cells during T1D pathogenesis. Similarly, FhHDM-1 protected primary human islets from cytokine-induced apoptosis. Importantly, while FhHDM-1 promoted β-cell survival, it did not induce proliferation. Collectively, these data indicate that FhHDM-1 has significant therapeutic applications to promote β-cell survival, which is required for T1D and T2D prevention and islet transplantation. KEY MESSAGES: FhHDM-1 preserves β-cell mass in NOD mice and prevents the development of T1D. FhHDM-1 enhances phosphorylation of Akt in mouse β-cell lines. FhHDM-1 increases levels of NADH/NADPH in mouse β-cell lines in vitro. FhHDM-1 prevents cytokine-induced cell death of mouse β-cell lines and primary human β-cells in vitro via activation of the PI3K/Akt pathway.
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Affiliation(s)
- Inah Camaya
- School of Life Sciences, Faculty of Science, the University of Technology Sydney, Ultimo, Australia
| | - Tsz Y Mok
- School of Life Sciences, Faculty of Science, the University of Technology Sydney, Ultimo, Australia
| | - Maria Lund
- School of Life Sciences, Faculty of Science, the University of Technology Sydney, Ultimo, Australia
| | - Joyce To
- School of Life Sciences, Faculty of Science, the University of Technology Sydney, Ultimo, Australia
| | - Nady Braidy
- Centre for Healthy Brain Ageing, University of New South Wales, Sydney, Randwick, Australia
| | - Mark W Robinson
- School of Biological Sciences, Queen's University, Belfast, Northern Ireland, UK
| | - Jerran Santos
- School of Life Sciences, Faculty of Science, the University of Technology Sydney, Ultimo, Australia
| | - Bronwyn O'Brien
- School of Life Sciences, Faculty of Science, the University of Technology Sydney, Ultimo, Australia
| | - Sheila Donnelly
- School of Life Sciences, Faculty of Science, the University of Technology Sydney, Ultimo, Australia.
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Arthur E, Kittur FS, Lin Y, Hung CY, Sane DC, Xie J. Plant-Produced Asialo-Erythropoietin Restores Pancreatic Beta-Cell Function by Suppressing Mammalian Sterile-20-like Kinase (MST1) and Caspase-3 Activation. Front Pharmacol 2017; 8:208. [PMID: 28469576 PMCID: PMC5395651 DOI: 10.3389/fphar.2017.00208] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/03/2017] [Indexed: 01/12/2023] Open
Abstract
Pancreatic beta-cell death adversely contributes to the progression of both type I and II diabetes by undermining beta-cell mass and subsequently diminishing endogenous insulin production. Therapeutics to impede or even reverse the apoptosis and dysfunction of beta-cells are urgently needed. Asialo-rhuEPO, an enzymatically desialylated form of recombinant human erythropoietin (rhuEPO), has been shown to have cardioprotective and neuroprotective functions but with no adverse effects like that of sialylated rhuEPO. Heretofore, the anti-apoptotic effect of asialo-rhuEPO on pancreatic beta-cells has not been reported. In the current study, we investigated the cytoprotective properties of plant-produced asialo-rhuEPO (asialo-rhuEPOP) against staurosporine-induced cell death in the pancreatic beta-cell line RIN-m5F. Our results showed that 60 IU/ml asialo-rhuEPOP provided 41% cytoprotection while 60 IU/ml rhuEPO yielded no effect. Western blotting results showed that asialo-rhuEPOP treatment inhibited both MST1 and caspase-3 activation with the retention of PDX1 and insulin levels close to untreated control cells. Our study provides the first evidence indicating that asialo-rhuEPOP-mediated protection involves the reduction of MST1 activation, which is considered a key mediator of apoptotic signaling in beta-cells. Considering the many advantages its plant-based expression, asialo-rhuEPOP could be potentially developed as a novel and inexpensive agent to treat or prevent diabetes after further performing studies in cell-based and animal models of diabetes.
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Affiliation(s)
- Elena Arthur
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, DurhamNC, USA
| | - Farooqahmed S Kittur
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, DurhamNC, USA
| | - Yuan Lin
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, DurhamNC, USA.,School of Basic Medical Sciences, Ningxia Medical UniversityYinchuan, China
| | - Chiu-Yueh Hung
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, DurhamNC, USA
| | - David C Sane
- Carilion Clinic and Virginia Tech Carilion School of Medicine, RoanokeVA, USA
| | - Jiahua Xie
- Department of Pharmaceutical Sciences, Biomanufacturing Research Institute and Technology Enterprise, North Carolina Central University, DurhamNC, USA
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Chen LN, Sun Q, Liu SQ, Hu H, Lv J, Ji WJ, Wang M, Chen MX, Zhou J. Erythropoietin improves glucose metabolism and pancreatic β-cell damage in experimental diabetic rats. Mol Med Rep 2015; 12:5391-8. [PMID: 26126591 DOI: 10.3892/mmr.2015.4006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 06/03/2015] [Indexed: 11/05/2022] Open
Abstract
Previous studies have implicated erythropoietin (EPO) signaling in the regulation of glucose metabolism. Whether EPO can be used treat diabetes and the underlying mechanism remain to be elucidated. The present study aimed to investigate whether EPO affects glucose metabolism, and the underlying mechanisms, in experimental diabetic rats. The effects of EPO (300 U/kg three times a week for 4 weeks) on glucose metabolism, hematopoietic function, blood selenium content and the ultrastructure of pancreatic β‑cells were investigated in low dose (25 mg/kg body weight) streptozotocin‑induced experimental diabetic rats provided with a high‑fat diet. The results demonstrated that EPO significantly decreased the fasting blood glucose, the area under the curve of the oral glucose tolerance and insulin tolerance tests and L‑alanine gluconeogenesis. Ultrastructural examination of the pancreatic islets revealed that EPO prevented the dysfunction of pancreatic β‑cells in experimental diabetic rats, ameliorated cytoplasmic vacuolation and fragmentation of mitochondria, and increased the number of secretory granules. EPO administration increased the activities of superoxide dismutase and glutathione peroxidase, and decreased the level of malondialdehyde. Additionally, EPO increased blood selenium in the diabetic rats and produced a hematopoietic effect. These results indicated that EPO modulated glucose metabolism and improved pancreatic β‑cells damage by increasing anti‑oxidation. The detailed mechanisms underlying these effects require further investigation.
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Affiliation(s)
- Li-Na Chen
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Qiang Sun
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Shu-Qing Liu
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Hao Hu
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Juan Lv
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Wen-Jun Ji
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Meng Wang
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Ming-Xia Chen
- Department of Electron Microscopy Room, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
| | - Jun Zhou
- Department of Pharmacology, School of Basic Medical Sciences, Xian Jiaotong University Health Science Center, Xian, Shaanxi 710061, P.R. China
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Caillaud C, Connes P, Ben Saad H, Mercier J. Erythropoietin enhances whole body lipid oxidation during prolonged exercise in humans. J Physiol Biochem 2015; 71:9-16. [DOI: 10.1007/s13105-014-0374-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/16/2014] [Indexed: 01/29/2023]
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Wang L, Di L, Noguchi CT. Erythropoietin, a novel versatile player regulating energy metabolism beyond the erythroid system. Int J Biol Sci 2014; 10:921-39. [PMID: 25170305 PMCID: PMC4147225 DOI: 10.7150/ijbs.9518] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 06/04/2014] [Indexed: 12/12/2022] Open
Abstract
Erythropoietin (EPO), the required cytokine for promoting the proliferation and differentiation of erythroid cells to stimulate erythropoiesis, has been reported to act as a pleiotropic cytokine beyond hematopoietic system. The various activities of EPO are determined by the widespread distribution of its cell surface EPO receptor (EpoR) in multiple tissues including endothelial, neural, myoblasts, adipocytes and other cell types. EPO activity has been linked to angiogenesis, neuroprotection, cardioprotection, stress protection, anti-inflammation and especially the energy metabolism regulation that is recently revealed. The investigations of EPO activity in animals and the expression analysis of EpoR provide more insights on the potential of EPO in regulating energy metabolism and homeostasis. The findings of crosstalk between EPO and some important energy sensors and the regulation of EPO in the cellular respiration and mitochondrial function further provide molecular mechanisms for EPO activity in metabolic activity regulation. In this review, we will summarize the roles of EPO in energy metabolism regulation and the activity of EPO in tissues that are tightly associated with energy metabolism. We will also discuss the effects of EPO in regulating oxidative metabolism and mitochondrial function, the interactions between EPO and important energy regulation factors, and the protective role of EPO from stresses that are related to metabolism, providing a brief overview of previously less appreciated EPO biological function in energy metabolism and homeostasis.
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Affiliation(s)
- Li Wang
- 1. Faculty of Health Sciences, University of Macau, SAR of People's Republic of China
| | - Lijun Di
- 1. Faculty of Health Sciences, University of Macau, SAR of People's Republic of China
| | - Constance Tom Noguchi
- 2. Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, U.S.A
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9
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Abstract
The hematopoietic growth factor erythropoietin (Epo) circulates in plasma and controls the oxygen carrying capacity of the blood (Fisher. Exp Biol Med (Maywood) 228:1-14, 2003). Epo is produced primarily in the adult kidney and fetal liver and was originally believed to play a role restricted to stimulation of early erythroid precursor proliferation, inhibition of apoptosis, and differentiation of the erythroid lineage. Early studies showed that mice with targeted deletion of Epo or the Epo receptor (EpoR) show impaired erythropoiesis, lack mature erythrocytes, and die in utero around embryonic day 13.5 (Wu et al. Cell 83:59-67, 1995; Lin et al. Genes Dev. 10:154-164, 1996). These animals also exhibited heart defects, abnormal vascular development as well as increased apoptosis in the brain suggesting additional functions for Epo signaling in normal development of the central nervous system and heart. Now, in addition to its well-known role in erythropoiesis, a diverse array of cells have been identified that produce Epo and/or express the Epo-R including endothelial cells, smooth muscle cells, and cells of the central nervous system (Masuda et al. J Biol Chem. 269:19488-19493, 1994; Marti et al. Eur J Neurosci. 8:666-676, 1996; Bernaudin et al. J Cereb Blood Flow Metab. 19:643-651, 1999; Li et al. Neurochem Res. 32:2132-2141, 2007). Endogenously produced Epo and/or expression of the EpoR gives rise to autocrine and paracrine signaling in different organs particularly during hypoxia, toxicity, and injury conditions. Epo has been shown to regulate a variety of cell functions such as calcium flux (Korbel et al. J Comp Physiol B. 174:121-128, 2004) neurotransmitter synthesis and cell survival (Velly et al. Pharmacol Ther. 128:445-459, 2010; Vogel et al. Blood. 102:2278-2284, 2003). Furthermore Epo has neurotrophic effects (Grimm et al. Nat Med. 8:718-724, 2002; Junk et al. Proc Natl Acad Sci U S A. 99:10659-10664, 2002), can induce an angiogenic phenotype in cultured endothelial cells and is a potent angiogenic factor in vivo (Ribatti et al. Eur J Clin Invest. 33:891-896, 2003) and might enhance ventilation in hypoxic conditions (Soliz et al. J Physiol. 568:559-571, 2005; Soliz et al. J Physiol. 583, 329-336, 2007). Thus multiple functions have been identified breathing new life and exciting possibilities into what is really an old growth factor.This review will address the function of Epo in non-hematopoietic tissues with significant emphasis on the brain and heart.
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Affiliation(s)
- Omolara O Ogunshola
- Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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Barlow AD, Xie J, Moore CE, Campbell SC, Shaw JAM, Nicholson ML, Herbert TP. Rapamycin toxicity in MIN6 cells and rat and human islets is mediated by the inhibition of mTOR complex 2 (mTORC2). Diabetologia 2012; 55:1355-65. [PMID: 22314813 PMCID: PMC3328678 DOI: 10.1007/s00125-012-2475-7] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 01/09/2012] [Indexed: 11/05/2022]
Abstract
AIMS/HYPOTHESIS Rapamycin (sirolimus) is one of the primary immunosuppressants for islet transplantation. Yet there is evidence that the long-term treatment of islet-transplant patients with rapamycin may be responsible for subsequent loss of islet graft function and viability. Therefore, the primary objective of this study was to elucidate the molecular mechanism of rapamycin toxicity in beta cells. METHODS Experiments were performed on isolated rat and human islets of Langerhans and MIN6 cells. The effects of rapamycin and the roles of mammalian target of rapamycin complex 2 (mTORC2)/protein kinase B (PKB) on beta cell signalling, function and viability were investigated using cell viability assays, insulin ELISA assays, kinase assays, western blotting, pharmacological inhibitors, small interfering (si)RNA and through the overproduction of a constitutively active mutant of PKB. RESULTS Rapamycin treatment of MIN6 cells and islets of Langerhans resulted in a loss of cell function and viability. Although rapamycin acutely inhibited mTOR complex 1 (mTORC1), the toxic effects of rapamycin were more closely correlated to the dissociation and inactivation of mTORC2 and the inhibition of PKB. Indeed, the overproduction of constitutively active PKB protected islets from rapamycin toxicity whereas the inhibition of PKB led to a loss of cell viability. Moreover, the selective inactivation of mTORC2 using siRNA directed towards rapamycin-insensitive companion of target of rapamycin (RICTOR), mimicked the toxic effects of chronic rapamycin treatment. CONCLUSIONS/INTERPRETATION This report provides evidence that rapamycin toxicity is mediated by the inactivation of mTORC2 and the inhibition of PKB and thus reveals the molecular basis of rapamycin toxicity and the essential role of mTORC2 in maintaining beta cell function and survival.
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Affiliation(s)
- A. D. Barlow
- Transplant Surgery Group, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - J. Xie
- Department of Cell Physiology and Pharmacology, University of Leicester, The Henry Wellcome Building, University Road, Leicester, LE1 9HN UK
| | - C. E. Moore
- Department of Cell Physiology and Pharmacology, University of Leicester, The Henry Wellcome Building, University Road, Leicester, LE1 9HN UK
| | - S. C. Campbell
- Institute of Cellular Medicine, Newcastle University, Newcastle, UK
| | - J. A. M. Shaw
- Institute of Cellular Medicine, Newcastle University, Newcastle, UK
| | - M. L. Nicholson
- Transplant Surgery Group, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - T. P. Herbert
- Department of Cell Physiology and Pharmacology, University of Leicester, The Henry Wellcome Building, University Road, Leicester, LE1 9HN UK
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Wu Z, Mata M, Fink DJ. Prolonged regulatable expression of EPO from an HSV vector using the LAP2 promoter element. Gene Ther 2011; 19:1107-13. [PMID: 22089494 DOI: 10.1038/gt.2011.188] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We previously reported regulated expression of erythropoietin (EPO) over 4 weeks in the peripheral nerve in vivo, using a herpes simplex virus (HSV)-based vector containing a Tet-on regulatable gene expression cassette. To create a vector that would be appropriate for the treatment of chronic neuropathy, we constructed a HSV vector with expression of EPO under the control of the Tet-on system in which the HSV latency-associated promoter 2 element was used to drive the expression of the Tet-on transactivator. EPO expression from the vector was tightly controlled by administration of doxycycline (DOX) in vitro. One month after inoculation of the vector to transduce dorsal root ganglion (DRG) in vivo, administration of DOX-containing chow-induced expression of EPO. Mice with streptozotocin-induced diabetes, inoculated with the vector, were protected against the development of neuropathy by continuous administration of DOX-containing chow over the course of 3 months. Identical results were achieved when DOX was administered every other week over 3 months of diabetes, but administration of DOX, 1 week out of 3, provided only partial protection against the development of neuropathy. Taken together, these results suggest such a vector is well suited for clinical trial for the treatment of chronic or subacutely developing neuropathy.
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Affiliation(s)
- Z Wu
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System, Ann Arbor, MI 48109, USA
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Chateauvieux S, Grigorakaki C, Morceau F, Dicato M, Diederich M. Erythropoietin, erythropoiesis and beyond. Biochem Pharmacol 2011; 82:1291-303. [DOI: 10.1016/j.bcp.2011.06.045] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 06/28/2011] [Accepted: 06/29/2011] [Indexed: 12/21/2022]
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