1
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Exendin-4 alleviates myocardial ischemia reperfusion injury by enhancing autophagy through promoting nuclear translocation of TFEB. Exp Cell Res 2023; 423:113469. [PMID: 36627100 DOI: 10.1016/j.yexcr.2023.113469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 01/06/2023] [Indexed: 01/09/2023]
Abstract
Ischemia-reperfusion (I/R) injury (IRI) is a common clinical consequence of myocardial infarction. Exendin-4 is a glucagon-like peptide-1 (GLP-1) analog that has been demonstrated to alleviate myocardial IRI. Autophagy, a lysosomal pathway balancing cell survival and cell death, is engaged in myocardial IRI. However, whether exendin-4 exerts a protective effect on myocardial IRI by modulating autophagy remains elusive. Herein, we investigated the effect of exendin-4 on autophagic flux and explored the underlying molecular mechanisms. Our data revealed that the autophagic flux was blocked in the human ventricular cardiomyocyte cell lines (AC16) subjected to oxygen glucose deprivation/reoxygenation (OGD/R) in vitro. Exendin-4 pre-treatment markedly restored the blocked autophagic flux induced by OGD/R through promoting nuclear translocation of TFEB and transcription of genes involving autophagy initiation, the effect of which was reversed by TFEB knockdown. The restoration of autophagic flux contributed to multiple beneficial effects of exendin-4 in cardiomyocytes, including reduction of oxidative stress, preservation of mitochondrial network as well as inhibition of cytochrome c leakage from mitochondrial permeability transition pore (MPTP) and the resulting apoptosis. Moreover, the administration of exendin-4 reduced infarct size and preserved cardiac function through its anti-apoptosis and antioxidative effects in vivo. These results shed some light on understanding the novel mechanism of exendin-4 as a protective agent against myocardial IRI.
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2
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Metzger K, Kalbe C, Siengdee P, Ponsuksili S. The effects of temperature and donor piglet age on the transcriptomic profile and energy metabolism of myoblasts. Front Physiol 2022; 13:979283. [PMID: 36213238 PMCID: PMC9532859 DOI: 10.3389/fphys.2022.979283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/30/2022] [Indexed: 11/13/2022] Open
Abstract
Rapid climate change is associated with frequent extreme heat events and the resulting thermal stress has consequences for the health, welfare, and growth of farm animals. The aim of this study was to characterize the transcriptional changes and the effects on energy metabolism in proliferating porcine myoblasts derived from piglets of different ages, representing differences in thermoregulatory abilities, and cultivated below (35°C) and above (39°C, 41°C) the standard cultivation temperature (37°C). Satellite cells originating from Musculus rhomboideus of piglets isolated on days 5 (P5, thermolabile) and 20 (P20, thermostable) of age were used. Our expression analyses highlighted differentially expressed genes in porcine myoblasts cultures under heat or cold induced stress. These gene sets showed enrichment for biological processes and pathways related to organelle fission, cell cycle, chromosome organization, and DNA replication. Culture at 35°C resulted in increased metabolic flux as well as a greater abundance of transcripts of the cold shock protein-encoding gene RBM3 and those of genes related to biological processes and signaling pathways, especially those involving the immune system (cytokine–cytokine receptor interaction, TNF and IL-17 signaling pathways). For cultivation at 39°C, differences in the expression of genes related to DNA replication and cell growth were identified. The highest glutathione index ratio was also found under 39°C. Meanwhile, cultivation at 41°C induced a heat stress response, including the upregulation of HSP70 expression and the downregulation of many biological processes and signaling pathways related to proliferative ability. Our analysis also identified differentially expressed genes between cells of donors with a not yet (P5) and already fully developed (P20) capacity for thermoregulation at different cultivation temperatures. When comparing P5 and P20, most of the changes in gene expression were detected at 37°C. At this optimal temperature, muscle cells can develop to their full capacity. Therefore, the most diverse molecular signaling pathways, including PI3K-Akt signaling, Wnt signaling, and EGFR tyrosine kinase inhibitor, were found and are more pronounced in muscle cells from 20-day-old piglets. These results contribute to a better understanding of the mechanisms underlying the adaptation of skeletal muscle cells to temperature stress in terms of their thermoregulatory ability.
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Affiliation(s)
- Katharina Metzger
- Research Institute for Farm Animal Biology (FBN), Institute of Muscle Biology and Growth, Dummerstorf, Germany
- Research Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Dummerstorf, Germany
| | - Claudia Kalbe
- Research Institute for Farm Animal Biology (FBN), Institute of Muscle Biology and Growth, Dummerstorf, Germany
| | - Puntita Siengdee
- Research Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Dummerstorf, Germany
| | - Siriluck Ponsuksili
- Research Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Dummerstorf, Germany
- *Correspondence: Siriluck Ponsuksili,
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3
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Cignarelli A, Genchi VA, Le Grazie G, Caruso I, Marrano N, Biondi G, D’Oria R, Sorice GP, Natalicchio A, Perrini S, Laviola L, Giorgino F. Mini Review: Effect of GLP-1 Receptor Agonists and SGLT-2 Inhibitors on the Growth Hormone/IGF Axis. Front Endocrinol (Lausanne) 2022; 13:846903. [PMID: 35265043 PMCID: PMC8899086 DOI: 10.3389/fendo.2022.846903] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/01/2022] [Indexed: 11/13/2022] Open
Abstract
Accumulating evidence supports the early use of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and sodium glucose transporter-2 inhibitors (SGLT-2is) for the treatment of type 2 diabetes. Indeed, these compounds exert numerous pleiotropic actions that favorably affect metabolism and diabetes comorbidities, showing an additional effect beyond glucose control. Although a substantial amount of knowledge has been generated regarding the mechanism of action of both drug classes, much remains to be understood. Growth hormone (GH) is an important driver for multiple endocrine responses involving changes in glucose and lipid metabolism, and affects several tissues and organs (e.g., bone, heart). It acts directly on several target tissues, including skeletal muscle and bone, but several effects are mediated indirectly by circulating (liver-derived) or locally produced IGF-1. In consideration of the multiple metabolic and cardiovascular effects seen in subjects treated with GLP-1RAs and SGLT-2is (e.g., reduction of hyperglycemia, weight loss, free/fat mass and bone remodeling, anti-atherosclerosis, natriuresis), it is reasonable to speculate that GH and IGF-1 may play a about a relevant role in this context. This narrative mini-review aims to describe the involvement of the GH/IGF-1/IGF-1R axis in either mediating or responding to the effects of each of the two drug classes.
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Xie J, Shen K, Jones AT, Yang J, Tee AR, Shen MH, Yu M, Irani S, Wong D, Merrett JE, Lenchine RV, De Poi S, Jensen KB, Trim PJ, Snel MF, Kamei M, Martin SK, Fitter S, Tian S, Wang X, Butler LM, Zannettino ACW, Proud CG. Reciprocal signaling between mTORC1 and MNK2 controls cell growth and oncogenesis. Cell Mol Life Sci 2021; 78:249-270. [PMID: 32170339 PMCID: PMC11068017 DOI: 10.1007/s00018-020-03491-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/23/2020] [Accepted: 02/17/2020] [Indexed: 12/21/2022]
Abstract
eIF4E plays key roles in protein synthesis and tumorigenesis. It is phosphorylated by the kinases MNK1 and MNK2. Binding of MNKs to eIF4G enhances their ability to phosphorylate eIF4E. Here, we show that mTORC1, a key regulator of mRNA translation and oncogenesis, directly phosphorylates MNK2 on Ser74. This suppresses MNK2 activity and impairs binding of MNK2 to eIF4G. These effects provide a novel mechanism by which mTORC1 signaling impairs the function of MNK2 and thereby decreases eIF4E phosphorylation. MNK2[S74A] knock-in cells show enhanced phosphorylation of eIF4E and S6K1 (i.e., increased mTORC1 signaling), enlarged cell size, and increased invasive and transformative capacities. MNK2[Ser74] phosphorylation was inversely correlated with disease progression in human prostate tumors. MNK inhibition exerted anti-proliferative effects in prostate cancer cells in vitro. These findings define a novel feedback loop whereby mTORC1 represses MNK2 activity and oncogenic signaling through eIF4E phosphorylation, allowing reciprocal regulation of these two oncogenic pathways.
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Affiliation(s)
- Jianling Xie
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
| | - Kaikai Shen
- Medical Research Council Toxicology Unit, Leicester, UK
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Ashley T Jones
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Jian Yang
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Andrew R Tee
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Ming Hong Shen
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Mengyuan Yu
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Swati Irani
- Adelaide Medical School and Freemasons Foundation Centre for Men's Health, University of Adelaide, Adelaide, Australia
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Derick Wong
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
| | - James E Merrett
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Roman V Lenchine
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Stuart De Poi
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Kirk B Jensen
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Paul J Trim
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Marten F Snel
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Makoto Kamei
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Sally Kim Martin
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Science, University of Adelaide, Adelaide, Australia
| | - Stephen Fitter
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Science, University of Adelaide, Adelaide, Australia
| | - Shuye Tian
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Xuemin Wang
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Lisa M Butler
- Adelaide Medical School and Freemasons Foundation Centre for Men's Health, University of Adelaide, Adelaide, Australia
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Andrew C W Zannettino
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Science, University of Adelaide, Adelaide, Australia
| | - Christopher G Proud
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia.
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia.
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Zaky DA, Abouelfadl DM, Nassar NN, Abdallah DM, Al-Shorbagy MY. The paradox of dipeptidyl peptidase IV inhibition in enterocytic differentiation and epithelial-mesenchymal transition in rat cholestatic sepsis. Toxicol Appl Pharmacol 2020; 394:114956. [PMID: 32171571 DOI: 10.1016/j.taap.2020.114956] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/19/2020] [Accepted: 03/10/2020] [Indexed: 12/16/2022]
Abstract
Proper enterocytic proliferation/differentiation, besides providing adequate adherens junctions (AJ) integrity, are responsible for strengthening of the gut barrier that acts as a first line defense against endotoxemia. However, the preferential role of the underlying PI3K/Akt (PKB) axis in triggering enterocytic proliferation/differentiation signaling and AJ assembly is still obscure in sepsis. Additionally, the potential involvement of dipeptidyl peptidase (DPP)-IV in cholestatic sepsis has not yet been reported. Common bile duct ligation (CBDL) insult was performed in adult male Sprague-Dawley rats except for sham operated animals; three doses of vildagliptin (VLD3, 10 and 30 mg/kg/d; p.o) were administered for 10 consecutive days post CBDL. VLD3/10/30 dose-dependently decreased DPP-IV and elevated GLP-1, IGF-1, PI3K, pS473-Akt (PKB), pS9-GSK-3β, pS133-CREB and cyclin-D1. VLD3/10 reduced fever, portal/aortic endotoxin and IgG, body weight loss as well as ileal NF-κB, TNF-α, MPO, TBARS, subepithelial/pericryptal and submucosal collagen deposition, vimentin immunoreactivity, N-cadherin, Zeb1 and pY654-β-catenin but increased E-cadherin, NPSH and colon/spleen indices - effects that were quite the opposite of VLD30. Accordingly, maintaining proper enterocytic proliferation/differentiation and phosphorylation inputs consequent to adequate DPP-IV inhibition is integral to AJ assembly in cholestatic sepsis; however, perturbed signals by excessive suppression of the enzyme activity induce toxic effects manifested as AJ disassembly and EMT, hence gut leakage and overt endotoxemia.
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Affiliation(s)
- Doaa A Zaky
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Kasr El-Aini street, Cairo, P.O. Box 11562, Egypt.
| | | | - Noha N Nassar
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Kasr El-Aini street, Cairo, P.O. Box 11562, Egypt
| | - Dalaal M Abdallah
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Kasr El-Aini street, Cairo, P.O. Box 11562, Egypt
| | - Muhammad Y Al-Shorbagy
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Kasr El-Aini street, Cairo, P.O. Box 11562, Egypt; School of Pharmacy, NewGiza University, Giza, Egypt
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6
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Abstract
PURPOSE OF REVIEW Pancreatic β-cells play a critical role in whole-body glucose homeostasis by regulating the release of insulin in response to minute by minute alterations in metabolic demand. As such, β-cells are staunchly resilient but there are circumstances where they can become functionally compromised or physically lost due to pathophysiological changes which culminate in overt hyperglycemia and diabetes. RECENT FINDINGS In humans, β-cell mass appears to be largely defined in the postnatal period and this early replicative and generative phase is followed by a refractory state which persists throughout life. Despite this, efforts to identify physiological and pharmacological factors which might re-initiate β-cell replication (or cause the replenishment of β-cells by neogenesis or transdifferentiation) are beginning to bear fruit. Controlled manipulation of β-cell mass in humans still represents a holy grail for therapeutic intervention in diabetes, but progress is being made which may lead to ultimate success.
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Affiliation(s)
- Giorgio Basile
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Harvard Stem Cell Institute, Boston, MA 02215, USA
| | - Rohit N. Kulkarni
- Islet Cell and Regenerative Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Harvard Stem Cell Institute, Boston, MA 02215, USA
| | - Noel G. Morgan
- Institute of Biomedical & Clinical Science, University of Exeter Medical School, Exeter EX2 5DW, UK
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7
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Liang H, Nie J, Van Skike CE, Valentine JM, Orr ME. Mammalian Target of Rapamycin at the Crossroad Between Alzheimer's Disease and Diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1128:185-225. [PMID: 31062331 DOI: 10.1007/978-981-13-3540-2_10] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Accumulating evidence suggests that Alzheimer's disease may manifest as a metabolic disorder with pathology and/or dysfunction in numerous tissues. Adults with Alzheimer's disease suffer with significantly more comorbidities than demographically matched Medicare beneficiaries (Zhao et al, BMC Health Serv Res 8:108, 2008b). Reciprocally, comorbid health conditions increase the risk of developing Alzheimer's disease (Haaksma et al, PLoS One 12(5):e0177044, 2017). Type 2 diabetes mellitus is especially notable as the disease shares many overlapping pathologies observed in patients with Alzheimer's disease, including hyperglycemia, hyperinsulinemia, insulin resistance, glucose intolerance, dyslipidemia, inflammation, and cognitive dysfunction, as described in Chap. 8 of this book (Yoshitake et al, Neurology 45(6):1161-1168, 1995; Leibson et al, Am J Epidemiol 145(4):301-308, 1997; Ott et al, Neurology 53(9):1937-1942, 1999; Voisin et al, Rev Med Interne 24(Suppl 3):288s-291s, 2003; Janson et al. Diabetes 53(2):474-481, 2004; Ristow M, J Mol Med (Berl) 82(8):510-529, 2004; Whitmer et al, BMJ 330(7504):1360, 2005, Curr Alzheimer Res 4(2):103-109, 2007; Ohara et al, Neurology 77(12):1126-1134, 2011). Although nondiabetic older adults also experience age-related cognitive decline, diabetes is uniquely associated with a twofold increased risk of Alzheimer's disease, as described in Chap. 2 of this book (Yoshitake et al, Neurology 45(6):1161-1168, 1995; Leibson et al, Am J Epidemiol 145(4):301-308, 1997; Ott et al. Neurology 53(9):1937-1942, 1999; Ohara et al, Neurology 77(12):1126-1134, 2011). Good glycemic control has been shown to improve cognitive status (Cukierman-et al, Diabetes Care 32(2):221-226, 2009), and the use of insulin sensitizers is correlated with a lower rate of cognitive decline in older adults (Morris JK, Burns JM, Curr Neurol Neurosci Rep 12(5):520-527, 2012). At the molecular level, the mechanistic/mammalian target of rapamycin (mTOR) plays a key role in maintaining energy homeostasis. Nutrient availability and cellular stress information, both extracellular and intracellular, are integrated and transduced through mTOR signaling pathways. Aberrant regulation of mTOR occurs in the brains of patients with Alzheimer's disease and in numerous tissues of individuals with type 2 diabetes (Mannaa et al, J Mol Med (Berl) 91(10):1167-1175, 2013). Moreover, modulating mTOR activity with a pharmacological inhibitor, rapamycin, provides wide-ranging health benefits, including healthy life span extension in numerous model organisms (Vellai et al, Nature 426(6967):620, 2003; Jia et al, Development 131(16):3897-3906, 2004; Kapahi et al, Curr Biol 14(10):885-890, 2004; Kaeberlein et al, Science 310(5751):1193-1196, 2005; Powers et al, Genes Dev 20(2):174-184, 2006; Harrison et al, Nature 460(7253):392-395, 2009; Selman et al, Science 326(5949):140-144, 2009; Sharp ZD, Strong R, J Gerontol A Biol Sci Med Sci 65(6):580-589, 2010), which underscores its importance to overall organismal health and longevity. In this chapter, we discuss the physiological role of mTOR signaling and the consequences of mTOR dysregulation in the brain and peripheral tissues, with emphasis on its relevance to the development of Alzheimer's disease and link to type 2 diabetes.
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Affiliation(s)
- Hanyu Liang
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Jia Nie
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Candice E Van Skike
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Joseph M Valentine
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Miranda E Orr
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- San Antonio Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, TX, USA.
- Glenn Biggs Institute for Alzheimer's & Neurodegenerative Diseases, San Antonio, TX, USA.
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8
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Ye R, Gordillo R, Shao M, Onodera T, Chen Z, Chen S, Lin X, SoRelle JA, Li X, Tang M, Keller MP, Kuliawat R, Attie AD, Gupta RK, Holland WL, Beutler B, Herz J, Scherer PE. Intracellular lipid metabolism impairs β cell compensation during diet-induced obesity. J Clin Invest 2018; 128:1178-1189. [PMID: 29457786 DOI: 10.1172/jci97702] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/09/2018] [Indexed: 12/16/2022] Open
Abstract
The compensatory proliferation of insulin-producing β cells is critical to maintaining glucose homeostasis at the early stage of type 2 diabetes. Failure of β cells to proliferate results in hyperglycemia and insulin dependence in patients. To understand the effect of the interplay between β cell compensation and lipid metabolism upon obesity and peripheral insulin resistance, we eliminated LDL receptor-related protein 1 (LRP1), a pleiotropic mediator of cholesterol, insulin, energy metabolism, and other cellular processes, in β cells. Upon high-fat diet exposure, LRP1 ablation significantly impaired insulin secretion and proliferation of β cells. The diminished insulin signaling was partly contributed to by the hypersensitivity to glucose-induced, Ca2+-dependent activation of Erk and the mTORC1 effector p85 S6K1. Surprisingly, in LRP1-deficient islets, lipotoxic sphingolipids were mitigated by improved lipid metabolism, mediated at least in part by the master transcriptional regulator PPARγ2. Acute overexpression of PPARγ2 in β cells impaired insulin signaling and insulin secretion. Elimination of Apbb2, a functional regulator of LRP1 cytoplasmic domain, also impaired β cell function in a similar fashion. In summary, our results uncover the double-edged effects of intracellular lipid metabolism on β cell function and viability in obesity and type 2 diabetes and highlight LRP1 as an essential regulator of these processes.
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Affiliation(s)
- Risheng Ye
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA.,Department of Medical Education, Texas Tech University Health Sciences Center Paul L. Foster School of Medicine, El Paso, Texas, USA
| | - Ruth Gordillo
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
| | - Mengle Shao
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
| | - Toshiharu Onodera
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
| | - Zhe Chen
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA.,Center for the Genetics of Host Defense, UTSW Medical Center, Dallas, Texas, USA
| | - Shiuhwei Chen
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
| | - Xiaoli Lin
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
| | - Jeffrey A SoRelle
- Center for the Genetics of Host Defense, UTSW Medical Center, Dallas, Texas, USA
| | - Xiaohong Li
- Center for the Genetics of Host Defense, UTSW Medical Center, Dallas, Texas, USA
| | - Miao Tang
- Center for the Genetics of Host Defense, UTSW Medical Center, Dallas, Texas, USA
| | - Mark P Keller
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, USA
| | - Regina Kuliawat
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, New York, New York, USA
| | - Alan D Attie
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, USA
| | - Rana K Gupta
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
| | - William L Holland
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
| | - Bruce Beutler
- Center for the Genetics of Host Defense, UTSW Medical Center, Dallas, Texas, USA
| | - Joachim Herz
- Departments of Molecular Genetics, Neuroscience, Neurology and Neurotherapeutics, and Center for Translational Neurodegeneration Research, UTSW Medical Center, Dallas, Texas, USA.,Center for Neuroscience, Department of Neuroanatomy, Albert Ludwig University, Freiburg, Germany
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern (UTSW) Medical Center, Dallas, Texas, USA
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9
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Ardestani A, Lupse B, Kido Y, Leibowitz G, Maedler K. mTORC1 Signaling: A Double-Edged Sword in Diabetic β Cells. Cell Metab 2018; 27:314-331. [PMID: 29275961 DOI: 10.1016/j.cmet.2017.11.004] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/11/2017] [Accepted: 11/15/2017] [Indexed: 12/21/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a central regulator of metabolic and nutrient cues that integrates environmental inputs into downstream signaling pathways to control cellular metabolism, growth, and survival. While numerous in vitro and in vivo studies reported the positive functions of mTORC1 in the regulation of β cell survival and proliferation under physiological conditions, more recent work demonstrates the opposite in the long term; this is exemplified by the constitutive inappropriate hyper-activation of mTORC1 in diabetic islets or β cells under conditions of increased β cell stress and metabolic demands. These recent findings uncover mTORC1's importance as an emerging significant player in the development and progression of β cell failure in type 2 diabetes and suggest that mTORC1 may act as a "double edge sword" in the regulation of β cell mass and function in response to metabolic stress such as nutrient overload and insulin resistance.
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Affiliation(s)
- Amin Ardestani
- University of Bremen, Centre for Biomolecular Interactions Bremen, Bremen 28359, Germany.
| | - Blaz Lupse
- University of Bremen, Centre for Biomolecular Interactions Bremen, Bremen 28359, Germany
| | - Yoshiaki Kido
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan; Division of Metabolism and Disease, Department of Biophysics, Kobe University Graduate School of Health Sciences, Kobe 654-0142, Japan
| | - Gil Leibowitz
- Endocrinology and Metabolism Service and the Hadassah Diabetes Unit, Department of Medicine, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Kathrin Maedler
- University of Bremen, Centre for Biomolecular Interactions Bremen, Bremen 28359, Germany.
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10
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Muhammad AB, Xing B, Liu C, Naji A, Ma X, Simmons RA, Hua X. Menin and PRMT5 suppress GLP1 receptor transcript and PKA-mediated phosphorylation of FOXO1 and CREB. Am J Physiol Endocrinol Metab 2017; 313:E148-E166. [PMID: 28270438 PMCID: PMC5582886 DOI: 10.1152/ajpendo.00241.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 01/11/2017] [Accepted: 02/20/2017] [Indexed: 12/23/2022]
Abstract
Menin is a scaffold protein that interacts with several epigenetic mediators to regulate gene transcription, and suppresses pancreatic β-cell proliferation. Tamoxifen-inducible deletion of multiple endocrine neoplasia type 1 (MEN1) gene, which encodes the protein menin, increases β-cell mass in multiple murine models of diabetes and ameliorates diabetes. Glucagon-like-peptide-1 (GLP1) is another key physiological modulator of β-cell mass and glucose homeostasis. However, it is not clearly understood whether menin crosstalks with GLP1 signaling. Here, we show that menin and protein arginine methyltransferase 5 (PRMT5) suppress GLP1 receptor (GLP1R) transcript levels. Notably, a GLP1R agonist induces phosphorylation of forkhead box protein O1 (FOXO1) at S253, and the phosphorylation is mediated by PKA. Interestingly, menin suppresses GLP1-induced and PKA-mediated phosphorylation of both FOXO1 and cAMP response element binding protein (CREB), likely through a protein arginine methyltransferase. Menin-mediated suppression of FOXO1 and CREB phosphorylation increases FOXO1 levels and suppresses CREB target genes, respectively. A small-molecule menin inhibitor reverses menin-mediated suppression of both FOXO1 and CREB phosphorylation. In addition, ex vivo treatment of both mouse and human pancreatic islets with a menin inhibitor increases levels of proliferation marker Ki67. In conclusion, our results suggest that menin and PRMT5 suppress GLP1R transcript levels and PKA-mediated phosphorylation of FOXO1 and CREB, and a menin inhibitor may reverse this suppression to induce β-cell proliferation.
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Affiliation(s)
- Abdul Bari Muhammad
- Abramson Family Cancer Research Institute, Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Bowen Xing
- Shenzen University School of Medicine, Institute of Diabetes Research, Shenzhen, Guangdong, China
| | - Chengyang Liu
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ali Naji
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Xiaosong Ma
- Shenzen University School of Medicine, Institute of Diabetes Research, Shenzhen, Guangdong, China
| | - Rebecca A Simmons
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and
- Division of Neonatology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Xianxin Hua
- Abramson Family Cancer Research Institute, Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
- Institute for Diabetes, Obesity, and Metabolism Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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11
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Li L. The Molecular Mechanism of Glucagon-Like Peptide-1 Therapy in Alzheimer's Disease, Based on a Mechanistic Target of Rapamycin Pathway. CNS Drugs 2017; 31:535-549. [PMID: 28540646 DOI: 10.1007/s40263-017-0431-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The mechanistic target of rapamycin (mTOR) is an important molecule that connects aging, lifespan, energy balance, glucose and lipid metabolism, and neurodegeneration. Rapamycin exerts effects in numerous biological activities via its target protein, playing a key role in energy balance, regulation of autophagy, extension of lifespan, immunosuppression, and protection against neurodegeneration. There are many similar pathophysiological processes and molecular pathways between Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM), and pharmacologic agents used to treat T2DM, including glucagon-like peptide-1 (GLP-1) analogs, seem to be beneficial for AD. mTOR mediates the effects of GLP-1 analogs in the treatment of T2DM; hence, I hypothesize that mTOR is a key molecule for mediating the protective effects of GLP-1 for AD.
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Affiliation(s)
- Lin Li
- Key Laboratory of Cellular Physiology, Shanxi Medical University, Taiyuan, Shanxi, China.
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12
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GLP-1 receptor signalling promotes β-cell glucose metabolism via mTOR-dependent HIF-1α activation. Sci Rep 2017; 7:2661. [PMID: 28572610 PMCID: PMC5454020 DOI: 10.1038/s41598-017-02838-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/19/2017] [Indexed: 02/05/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) promotes insulin secretion from pancreatic β-cells in a glucose dependent manner. Several pathways mediate this action by rapid, kinase phosphorylation-dependent, but gene expression-independent mechanisms. Since GLP-1-induced insulin secretion requires glucose metabolism, we aimed to address the hypothesis that GLP-1 receptor (GLP-1R) signalling can modulate glucose uptake and utilization in β-cells. We have assessed various metabolic parameters after short and long exposure of clonal BRIN-BD11 β-cells and rodent islets to the GLP-1R agonist Exendin-4 (50 nM). Here we report for the first time that prolonged stimulation of the GLP-1R for 18 hours promotes metabolic reprogramming of β-cells. This is evidenced by up-regulation of glycolytic enzyme expression, increased rates of glucose uptake and consumption, as well as augmented ATP content, insulin secretion and glycolytic flux after removal of Exendin-4. In our model, depletion of Hypoxia-Inducible Factor 1 alpha (HIF-1α) impaired the effects of Exendin-4 on glucose metabolism, while pharmacological inhibition of Phosphoinositide 3-kinase (PI3K) or mTOR completely abolished such effects. Considering the central role of glucose catabolism for stimulus-secretion coupling in β-cells, our findings suggest that chronic GLP-1 actions on insulin secretion include elevated β-cell glucose metabolism. Moreover, our data reveal novel aspects of GLP-1 stimulated insulin secretion involving de novo gene expression.
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13
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Wu X, Liang W, Guan H, Liu J, Liu L, Li H, He X, Zheng J, Chen J, Cao X, Li Y. Exendin-4 promotes pancreatic β-cell proliferation via inhibiting the expression of Wnt5a. Endocrine 2017; 55:398-409. [PMID: 27826714 DOI: 10.1007/s12020-016-1160-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 10/25/2016] [Indexed: 01/07/2023]
Abstract
Exendin-4, a glucagon-like peptide-1 receptor agonist, is currently regarded as an effective therapeutic strategy for type-2 diabetes. Previous studies indicated that exendin-4 promoted β cell proliferation. However, the underlying mechanisms remain largely unknown. Recently it was reported that exendin-4 promoted pancreatic β cell proliferation by regulating the expression level of Wnt4. The present study was designed to investigate whether other Wnt isoforms take part in accommodation of β-cell proliferation. We found that exendin-4 promotes the proliferation and suppresses the expression of Wnt5a in INS-1 cell line and C57Bl/6 mouse pancreatic β-cells. Further mechanistic study demonstrated that exendin-4 promoted INS-1 cell proliferation partly through down-regulating the expression of Wnt5a. Furthermore, Wnt5a could induce the activation of calmodulin-dependent protein kinase II in INS-1 cells, thereby decreasing the cellular stable β-catenin and its nuclear translocation, and finally reduce the expression of cyclin D1. In addition, we also found that both of the receptors (Frz-2 and Ror-2) mediated the effect of Wnt5a on β cell line INS-1 proliferation. Taken together, this study suggests that Wnt5a plays a critical role in exendin-4-induced β-cell proliferation, indicating that Wnt5a might be a novel regulator in counterbalance of β cell mass.
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Affiliation(s)
- Xinger Wu
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- Southern Medical University, Guangzhou, China
| | - Weiwei Liang
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Hongyu Guan
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Juan Liu
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Liehua Liu
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Hai Li
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaoying He
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jing Zheng
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jie Chen
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaopei Cao
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yanbing Li
- Department of Endocrinology and Diabetes Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China.
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14
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Cheng Q, Beltran VD, Chan SMH, Brown JR, Bevington A, Herbert TP. System-L amino acid transporters play a key role in pancreatic β-cell signalling and function. J Mol Endocrinol 2016; 56:175-87. [PMID: 26647387 DOI: 10.1530/jme-15-0212] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The branched-chain amino acids (BCAA) leucine, isoleucine and valine, are essential amino acids that play a critical role in cellular signalling and metabolism. They acutely stimulate insulin secretion and activate the regulatory serine/threonine kinase mammalian target of rapamycin complex 1 (mTORC1), a kinase that promotes increased β-cell mass and function. The effects of BCAA on cellular function are dependent on their active transport into the mammalian cells via amino acid transporters and thus the expression and activity of these transporters likely influence β-cell signalling and function. In this report, we show that the System-L transporters are required for BCAA uptake into clonal β-cell lines and pancreatic islets, and that these are essential for signalling to mTORC1. Further investigation revealed that the System-L amino acid transporter 1 (LAT1) is abundantly expressed in the islets, and that knockdown of LAT1 using siRNA inhibits mTORC1 signalling, leucine-stimulated insulin secretion and islet cell proliferation. In summary, we show that the LAT1 is required for regulating β-cell signalling and function in islets and thus may be a novel pharmacological/nutritional target for the treatment and prevention of type 2 diabetes.
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Affiliation(s)
- Qi Cheng
- Research School of BiologyAustralian National University, Acton, Australia
| | - Violeta D Beltran
- Department of InfectionImmunity and Inflammation, University of Leicester, UK
| | - Stanley M H Chan
- Health Innovations Research Institute (HIRI)School of Medical Sciences, RMIT University, Bundoora, Australia
| | - Jeremy R Brown
- Department of InfectionImmunity and Inflammation, University of Leicester, UK
| | - Alan Bevington
- Department of InfectionImmunity and Inflammation, University of Leicester, UK
| | - Terence P Herbert
- Health Innovations Research Institute (HIRI)School of Medical Sciences, RMIT University, Bundoora, Australia
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15
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Feng Y, Su L, Zhong X, Guohong W, Xiao H, Li Y, Xiu L. Exendin-4 promotes proliferation and differentiation of MC3T3-E1 osteoblasts by MAPKs activation. J Mol Endocrinol 2016; 56:189-99. [PMID: 26647389 DOI: 10.1530/jme-15-0264] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 12/02/2015] [Indexed: 12/15/2022]
Abstract
Glucagon-like peptide-1 (GLP1) and its receptor agonist have been previously reported to play a positive role in bone metabolism in aged ovariectomized rats and insulin-resistant models. However, whether GLP1 has a direct effect on the proliferation and differentiation of osteoblasts or any cellular mechanism for this potential role is unknown. We examined the effects of the GLP1 receptor agonist exendin-4 on the proliferation, differentiation, and mineralization of mouse osteoblastic MC3T3-E1 cells. GLP1 receptor was detected in MC3T3-E1 cells by polymerase chain reaction (PCR) and Western blot assay. Cell proliferation was assessed using MTT assay, revealing that exendin-4 increased cell proliferation at effective concentrations between 10(-10) and 10(-5) M. Quantitative PCR analysis showed that exendin-4 increased the mRNA expression of the differentiation markers alkaline phosphatase (ALP), collagen-1 (COL1), osteocalcin (OC), and runt-related transcription factor 2 (RUNX2) under osteogenic conditions. Alizarin red staining confirmed that 10(-7) M exendin-4 increased osteoblast mineralization by 18.7%. Exendin-4 upregulated the phosphorylation of ERK1/2, p38, and JNK, with the peak effect at 1.5 h in the Western blot analysis. The use of selective MAPK inhibitors, namely PD98059, SB203580, and SP600125, blocked the effects of exendin-4 on kinase activation (ERK1/2, p38, and JNK), as well as cell proliferation and differentiation in MC3T3-E1 cells. These findings demonstrate that exendin-4 promotes both the proliferation and differentiation of preosteoblasts MC3T3-E1 via activation of the MAPK pathway.
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Affiliation(s)
- Yingyu Feng
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Lei Su
- Department of GeriatricsFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Xing Zhong
- Department of EndocrinologySecond Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People's Republic of China
| | - Wei Guohong
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Haipeng Xiao
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Yanbing Li
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Lingling Xiu
- Department of EndocrinologyFirst Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China
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16
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Stamateris RE, Sharma RB, Kong Y, Ebrahimpour P, Panday D, Ranganath P, Zou B, Levitt H, Parambil NA, O'Donnell CP, García-Ocaña A, Alonso LC. Glucose Induces Mouse β-Cell Proliferation via IRS2, MTOR, and Cyclin D2 but Not the Insulin Receptor. Diabetes 2016; 65:981-95. [PMID: 26740601 PMCID: PMC5314707 DOI: 10.2337/db15-0529] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 12/29/2015] [Indexed: 12/21/2022]
Abstract
An important goal in diabetes research is to understand the processes that trigger endogenous β-cell proliferation. Hyperglycemia induces β-cell replication, but the mechanism remains debated. A prime candidate is insulin, which acts locally through the insulin receptor. Having previously developed an in vivo mouse hyperglycemia model, we tested whether glucose induces β-cell proliferation through insulin signaling. By using mice lacking insulin signaling intermediate insulin receptor substrate 2 (IRS2), we confirmed that hyperglycemia-induced β-cell proliferation requires IRS2 both in vivo and ex vivo. Of note, insulin receptor activation was not required for glucose-induced proliferation, and insulin itself was not sufficient to drive replication. Glucose and insulin caused similar acute signaling in mouse islets, but chronic signaling differed markedly, with mammalian target of rapamycin (MTOR) and extracellular signal-related kinase (ERK) activation by glucose and AKT activation by insulin. MTOR but not ERK activation was required for glucose-induced proliferation. Cyclin D2 was necessary for glucose-induced β-cell proliferation. Cyclin D2 expression was reduced when either IRS2 or MTOR signaling was lost, and restoring cyclin D2 expression rescued the proliferation defect. Human islets shared many of these regulatory pathways. Taken together, these results support a model in which IRS2, MTOR, and cyclin D2, but not the insulin receptor, mediate glucose-induced proliferation.
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Affiliation(s)
- Rachel E Stamateris
- Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Rohit B Sharma
- Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Yahui Kong
- Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Pantea Ebrahimpour
- Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Deepika Panday
- Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Pavana Ranganath
- Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Baobo Zou
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Helena Levitt
- Division of Endocrinology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | | | - Christopher P O'Donnell
- Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Adolfo García-Ocaña
- Diabetes, Obesity and Metabolism Institute, Division of Endocrinology, Diabetes and Bone Disease, The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Laura C Alonso
- Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
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17
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Ding HH, Ni WJ, Tang LQ, Wei W. G protein-coupled receptors: potential therapeutic targets for diabetic nephropathy. J Recept Signal Transduct Res 2015; 36:411-421. [PMID: 26675443 DOI: 10.3109/10799893.2015.1122039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Diabetic nephropathy, a lethal microvascular complication of diabetes mellitus, is characterized by progressive albuminuria, excessive deposition of extracellular matrix, thickened glomerular basement membrane, podocyte abnormalities, and podocyte loss. The G protein-coupled receptors (GPCRs) have attracted considerable attention in diabetic nephropathy, but the specific effects have not been elucidated yet. Likewise, abnormal signaling pathways are closely interrelated to the pathologic process of diabetic nephropathy, despite the fact that the mechanisms have not been explored clearly. Therefore, GPCRs and its mediated signaling pathways are essential for priority research, so that preventative strategies and potential targets might be developed for diabetic nephropathy. This article will give us comprehensive overview of predominant GPCR types, roles, and correlative signaling pathways in diabetic nephropathy.
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Affiliation(s)
- Hai-Hua Ding
- a Key Laboratory of Anti-Inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-Inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University , Hefei, Anhui Province , People's Republic of China.,b Affiliated Anhui Provincial Hospital, Anhui Medical University , Hefei, Anhui Province , People's Republic of China
| | - Wei-Jian Ni
- b Affiliated Anhui Provincial Hospital, Anhui Medical University , Hefei, Anhui Province , People's Republic of China
| | - Li-Qin Tang
- b Affiliated Anhui Provincial Hospital, Anhui Medical University , Hefei, Anhui Province , People's Republic of China
| | - Wei Wei
- a Key Laboratory of Anti-Inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-Inflammatory and Immune Medicine, Institute of Clinical Pharmacology, Anhui Medical University , Hefei, Anhui Province , People's Republic of China
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18
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Abstract
Based on own translational research of the biochemical and hormonal effects of cow's milk consumption in humans, this review presents milk as a signaling system of mammalian evolution that activates the nutrient-sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), the pivotal regulator of translation. Milk, a mammary gland-derived secretory product, is required for species-specific gene-nutrient interactions that promote appropriate growth and development of the newborn mammal. This signaling system is highly conserved and tightly controlled by the lactation genome. Milk is sufficient to activate mTORC1, the crucial regulator of protein, lipid, and nucleotide synthesis orchestrating anabolism, cell growth and proliferation. To fulfill its mTORC1-activating function, milk delivers four key metabolic messengers: (1) essential branched-chain amino acids (BCAAs); (2) glutamine; (3) palmitic acid; and (4) bioactive exosomal microRNAs, which in a synergistical fashion promote mTORC1-dependent translation. In all mammals except Neolithic humans, postnatal activation of mTORC1 by milk intake is restricted to the postnatal lactation period. It is of critical concern that persistent hyperactivation of mTORC1 is associated with aging and the development of age-related disorders such as obesity, type 2 diabetes mellitus, cancer, and neurodegenerative diseases. Persistent mTORC1 activation promotes endoplasmic reticulum (ER) stress and drives an aimless quasi-program, which promotes aging and age-related diseases.
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19
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Stewart AF, Hussain MA, García-Ocaña A, Vasavada RC, Bhushan A, Bernal-Mizrachi E, Kulkarni RN. Human β-cell proliferation and intracellular signaling: part 3. Diabetes 2015; 64:1872-85. [PMID: 25999530 PMCID: PMC4439562 DOI: 10.2337/db14-1843] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This is the third in a series of Perspectives on intracellular signaling pathways coupled to proliferation in pancreatic β-cells. We contrast the large knowledge base in rodent β-cells with the more limited human database. With the increasing incidence of type 1 diabetes and the recognition that type 2 diabetes is also due in part to a deficiency of functioning β-cells, there is great urgency to identify therapeutic approaches to expand human β-cell numbers. Therapeutic approaches might include stem cell differentiation, transdifferentiation, or expansion of cadaver islets or residual endogenous β-cells. In these Perspectives, we focus on β-cell proliferation. Past Perspectives reviewed fundamental cell cycle regulation and its upstream regulation by insulin/IGF signaling via phosphatidylinositol-3 kinase/mammalian target of rapamycin signaling, glucose, glycogen synthase kinase-3 and liver kinase B1, protein kinase Cζ, calcium-calcineurin-nuclear factor of activated T cells, epidermal growth factor/platelet-derived growth factor family members, Wnt/β-catenin, leptin, and estrogen and progesterone. Here, we emphasize Janus kinase/signal transducers and activators of transcription, Ras/Raf/extracellular signal-related kinase, cadherins and integrins, G-protein-coupled receptors, and transforming growth factor β signaling. We hope these three Perspectives will serve to introduce these pathways to new researchers and will encourage additional investigators to focus on understanding how to harness key intracellular signaling pathways for therapeutic human β-cell regeneration for diabetes.
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Affiliation(s)
- Andrew F Stewart
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Mehboob A Hussain
- Departments of Medicine and Pediatrics, Johns Hopkins School of Medicine, Baltimore, MD
| | - Adolfo García-Ocaña
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Rupangi C Vasavada
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Anil Bhushan
- Diabetes Center, University of California, San Francisco, San Francisco, CA
| | - Ernesto Bernal-Mizrachi
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, Ann Arbor, MI, and VA Ann Arbor Healthcare System, Ann Arbor, MI
| | - Rohit N Kulkarni
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA
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