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Castiglione R, Vivacqua A, Santoro M, De Rose D, Peluso G, Panza S, Aquila S, D'Agata R. Glucagon-like Peptide-1 Acts as Signaling Mediator to Modulate Human Sperm Performance via Targeting Akt, JNK and IRS-1 Cell Signaling Cascades: Novel Insights into Sperm Physiopathology. J Clin Med 2023; 12:jcm12113844. [PMID: 37298039 DOI: 10.3390/jcm12113844] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/19/2023] [Accepted: 06/01/2023] [Indexed: 06/12/2023] Open
Abstract
Recent evidence suggests that the male gonad is a potential target of glucagon-like peptide-1 (GLP-1). We investigated the effects of glucagon-like peptide-1 (GLP-1) on sperm function and the molecular mechanisms through which it may act. Semen samples of healthy men were incubated in the presence or absence of a GLP-1 mimetic analog, exendin-4 (Exe). In a different analysis, sperm were exposed to tumor necrosis factor (TNF-α) alone and, in some tubes, TNF-α was added after previous exposure to exendin-4 (Exe). Sperm parameters and protein-kinase B (p-Akt), insulin receptor substrate-1 (p-IRS-1 Ser312), and c Jun N-terminal protein kinase (p-JNK Thr183/Tyr185) were considered and evaluated. Sperm parameters, when incubated for 4 h in a simple defined balanced salt solution lacking protein, declined progressively with incubation time. The maximum decline was associated with a significant decrease in phosphorylated protein kinase B (p-Akt), concomitantly to an increase in insulin receptor substrate-1 (p-IRS-1 Ser312) and c Jun N-terminal protein kinase (p-JNK Thr183/Tyr185). Preincubation with exendin-4 (Exe) prevented this decline and maintained sperm motility (progressive-PM and total-TM). TNF-α exposure resulted in decreased sperm motility (PM and TM) and viability (V) in a concentration-dependent manner. Exe addition attenuated this TNF-α negative effect on sperm parameters. Glucagon-like peptide-1 (GLP-1) also acts by reducing levels of the "negative" kinases p-IRS-1Ser312 and p-JNK. An imbalance involving these three kinases in sperm, as it occurs in somatic cells, is a novel scenario that may participate in sperm physiopathology.
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Affiliation(s)
- Roberto Castiglione
- Department of Experimental and Clinical Medicine, University of Catania, 95123 Catania, Italy
| | - Adele Vivacqua
- Department of Pharmacy and Science of Health and Nutrition, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
- Centro Sanitario, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
| | - Marta Santoro
- Department of Pharmacy and Science of Health and Nutrition, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
- Centro Sanitario, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
| | - Daniela De Rose
- Department of Pharmacy and Science of Health and Nutrition, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
- Centro Sanitario, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
| | - Giuseppina Peluso
- Unit of Physiophatology of Reproduction, Annunziata Hospital, 87100 Cosenza, Italy
| | - Salvatore Panza
- Department of Pharmacy and Science of Health and Nutrition, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
- Centro Sanitario, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
| | - Saveria Aquila
- Department of Pharmacy and Science of Health and Nutrition, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
- Centro Sanitario, University of Calabria, Arcavacata di Rende, 87036 Cosenza, Italy
| | - Rosario D'Agata
- Department of Experimental and Clinical Medicine, University of Catania, 95123 Catania, Italy
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Biondi G, Marrano N, Borrelli A, Rella M, Palma G, Calderoni I, Siciliano E, Lops P, Giorgino F, Natalicchio A. Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes. Int J Mol Sci 2022; 23:ijms23105522. [PMID: 35628332 PMCID: PMC9143684 DOI: 10.3390/ijms23105522] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 12/10/2022] Open
Abstract
The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.
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Bai C, Wang Y, Niu Z, Guan Y, Huang J, Nian X, Zuo F, Zhao J, Kazumi T, Wu B. Exenatide improves hepatocyte insulin resistance induced by different regional adipose tissue. Front Endocrinol (Lausanne) 2022; 13:1012904. [PMID: 36246878 PMCID: PMC9558273 DOI: 10.3389/fendo.2022.1012904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Accepted: 09/15/2022] [Indexed: 11/13/2022] Open
Abstract
Obesity is resulted from energy surplus and is characterized by abnormal adipose tissue accumulation and/or distribution. Adipokines secreted by different regional adipose tissue can induce changes in key proteins of the insulin signaling pathway in hepatocytes and result in impaired hepatic glucose metabolism. This study aimed to investigate whether exenatide affects key proteins of IRS2/PI3K/Akt2 signaling pathway in hepatocytes altered by the different regional fat depots. Six non-obese patients without endocrine diseases were selected as the research subjects. Their subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT)were co-cultured with HepG2 cells in the transwell chamber. In the presence or absence of exenatide, adipokines content in the supernatant of each experimental group was detected by ELISA. In addition, HepG2 cells in each co-culture group with and without insulin were collected, and the expression of key proteins IRS2, p-IRS2(S731), PI3K-p85, Akt2, and p-Akt2(S473) was detected by western blotting (WB). The results showed that the adipokines IL-8, MCP-1, VEGF, and sTNFR2 in the supernatant of HepG2 cells induced by different regional adipose tissue were significantly higher than those in the HepG2 group, and VAT released more adipokines than SAT. Furthermore, these adipokines were significantly inhibited by exenatide. Importantly, the different regional fat depot affects the IRS2/PI3K/Akt2 insulin signaling pathway of hepatocytes. Exenatide can up-regulate the expression of hepatocyte proteins IRS2, PI3K-p85, p-Akt2(S731) inhibited by adipose tissue, and down-regulate the expression of hepatocyte proteins p-IRS2(S731) promoted by adipose tissue. The effect of VAT on the expression of these key proteins in hepatocytes is more significant than that of SAT. But there was no statistical difference in the expression of Akt2 protein among each experimental group, suggesting that exenatide has no influence on the expression of Akt2 protein in hepatocytes. In conclusion, exenatide may improve hepatic insulin resistance (IR) by inhibiting adipokines and regulating the expression of key proteins in the IRS2/PI3K/Akt2 pathway.
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Affiliation(s)
- Chuanmin Bai
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
| | - Yujun Wang
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
| | - Zhi Niu
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
| | - Yaxin Guan
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
| | - Jingshan Huang
- School of Computing, University of South Alabama, Mobile, AL, United States
| | - Xin Nian
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
| | - Fan Zuo
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
| | - Juan Zhao
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
| | - Tsutomu Kazumi
- Open Research Center for Studying of Lifestyle−Related Diseases, Mukogawa Women’s University, Nishinomiya, Japan
- Research Institute for Nutrition Sciences, Mukogawa Women’s University, Nishinomiya, Japan
- Department of Medicine, Kohnan Kakogawa Hospital, Kakogawa, Japan
| | - Bin Wu
- Department of Endocrinology, First Affiliated Hospital, Kunming Medical University, Kunming, China
- *Correspondence: Bin Wu,
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Wu Y, Hu J, Long X, Pan Y, Mu J, Park KY, Zhao X. Lactobacillus plantarum ZS62 Alleviates Alcohol-Induced Gastric Injury in Mice via an Anti-Oxidative Mechanism. DRUG DESIGN DEVELOPMENT AND THERAPY 2021; 15:1667-1676. [PMID: 33911852 PMCID: PMC8075736 DOI: 10.2147/dddt.s292243] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 03/17/2021] [Indexed: 12/16/2022]
Abstract
Aim Gastric mucosal injury is a typical characteristic of gastric diseases. The prevalence of gastric mucosal injury caused by alcohol has been on the rise, which has been considered a serious problem. The purpose of this study is to explore the protective effect on gastric injury of Lactobacillus plantarum ZS62 (LP-ZS62) isolated from naturally fermented yak yoghurt. Methods We established a gastric injury model through alcohol and evaluated the protective effect of LP-ZS62 on gastric injury in mice. The injury to the gastric mucosa, histopathological sections, related biochemical indicators, and related genes were examined to evaluate the protective effect of LP-ZS62. Results LP-ZS62 effectively alleviated alcohol-induced gastric injury according to visual observations of gastric tissue and pathological tissue sections. The experimental results revealed that LP-ZS62 decreased malondialdehyde (MDA) level, and elevated superoxide dismutase (SOD) and glutathione (GSH) levels in gastric tissues. Additionally, LP-ZS62 increased glutathione peroxidase (GSH-Px), prostaglandin E2 (PGE2), and somatostatin (SS) levels. LP-ZS62 also decreased inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor-α (TNF-α) and IL-6 levels, and increased the anti-inflammatory cytokine IL-10 level. The quantitative polymerase chain reaction results showed that LP-ZS62 upregulated mRNA expression of nuclear factor E2-related factor 2 (Nrf2), copper/zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), catalase (CAT), gamma-glutamylcysteine synthetase (GSH1), and glutathione peroxidase (GSH-Px). Conclusion This study confirmed that LP-ZS62 alleviated alcohol-induced gastric injury by regulating antioxidant capacity. Therefore, LP-ZS62 could be developed as a probiotic product to treat alcoholic gastric injury.
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Affiliation(s)
- Ya Wu
- Chongqing Collaborative Innovation Center for Functional Food, Chongqing Engineering Research Center of Functional Food, Chongqing Engineering Laboratory for Research and Development of Functional Food, Chongqing University of Education, Chongqing, 400067, People's Republic of China.,College of Biological and Chemical Engineering, Chongqing University of Education, Chongqing, 400067, People's Republic of China
| | - Jing Hu
- Department of Pharmacy, Southwest Hospital, Army Medical University (Third Military Medical University), Chongqing, 400038, People's Republic of China
| | - Xingyao Long
- Chongqing Collaborative Innovation Center for Functional Food, Chongqing Engineering Research Center of Functional Food, Chongqing Engineering Laboratory for Research and Development of Functional Food, Chongqing University of Education, Chongqing, 400067, People's Republic of China.,Department of Food Science and Biotechnology, Cha University, Seongnam, 13488, South Korea
| | - Yanni Pan
- Chongqing Collaborative Innovation Center for Functional Food, Chongqing Engineering Research Center of Functional Food, Chongqing Engineering Laboratory for Research and Development of Functional Food, Chongqing University of Education, Chongqing, 400067, People's Republic of China.,Department of Food Science and Biotechnology, Cha University, Seongnam, 13488, South Korea
| | - Jianfei Mu
- Chongqing Collaborative Innovation Center for Functional Food, Chongqing Engineering Research Center of Functional Food, Chongqing Engineering Laboratory for Research and Development of Functional Food, Chongqing University of Education, Chongqing, 400067, People's Republic of China
| | - Kun-Young Park
- Chongqing Collaborative Innovation Center for Functional Food, Chongqing Engineering Research Center of Functional Food, Chongqing Engineering Laboratory for Research and Development of Functional Food, Chongqing University of Education, Chongqing, 400067, People's Republic of China.,Department of Food Science and Biotechnology, Cha University, Seongnam, 13488, South Korea
| | - Xin Zhao
- Chongqing Collaborative Innovation Center for Functional Food, Chongqing Engineering Research Center of Functional Food, Chongqing Engineering Laboratory for Research and Development of Functional Food, Chongqing University of Education, Chongqing, 400067, People's Republic of China
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Yamada N, Matsushima-Nishiwaki R, Kobayashi K, Tachi J, Kozawa O. GLP-1 reduces the migration of hepatocellular carcinoma cells via suppression of the stress-activated protein kinase/c-Jun N-terminal kinase pathway. Arch Biochem Biophys 2021; 703:108851. [PMID: 33771507 DOI: 10.1016/j.abb.2021.108851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/11/2021] [Accepted: 03/17/2021] [Indexed: 12/25/2022]
Abstract
Incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are hormones secreted from small intestine accompanied with oral intake. We previously showed that transforming growth factor (TGF)-α stimulates the migration of hepatocellular carcinoma (HCC) cells via mitogen-activated protein (MAP) kinases, AKT and Rho-kinase. However, it remains to be elucidated whether incretins affect HCC cell functions. In the present study, therefore, we investigated whether incretins affect the migration of HCC cells using human HCC-derived HuH7 cells. GLP-1, but not GIP, reduced both TGF-α- and hepatocyte growth factor (HGF)-induced cell migration. IBMX, an inhibitor of cyclic nucleotide phosphodiesterase, enhanced the suppressive effect of GLP-1. GLP-1 attenuated the phosphorylation of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) by TGF-α and HGF. Our results strongly suggest that GLP-1 suppresses TGF-α- and HGF-induced migration of HCC cells through inhibiting the SAPK/JNK signaling pathway, and that the inhibition by GLP-1 is due to cAMP production.
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Affiliation(s)
- Noriko Yamada
- Department of Pharmacology, Gifu University Graduate School of Medicine, 501-1194, Gifu, Japan
| | | | - Kaido Kobayashi
- Department of Pharmacology, Gifu University Graduate School of Medicine, 501-1194, Gifu, Japan
| | - Junko Tachi
- Department of Pharmacology, Gifu University Graduate School of Medicine, 501-1194, Gifu, Japan
| | - Osamu Kozawa
- Department of Pharmacology, Gifu University Graduate School of Medicine, 501-1194, Gifu, Japan.
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Marrano N, Biondi G, Borrelli A, Cignarelli A, Perrini S, Laviola L, Giorgino F, Natalicchio A. Irisin and Incretin Hormones: Similarities, Differences, and Implications in Type 2 Diabetes and Obesity. Biomolecules 2021; 11:286. [PMID: 33671882 PMCID: PMC7918991 DOI: 10.3390/biom11020286] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Revised: 02/09/2021] [Accepted: 02/12/2021] [Indexed: 12/11/2022] Open
Abstract
Incretins are gut hormones that potentiate glucose-stimulated insulin secretion (GSIS) after meals. Glucagon-like peptide-1 (GLP-1) is the most investigated incretin hormone, synthesized mainly by L cells in the lower gut tract. GLP-1 promotes β-cell function and survival and exerts beneficial effects in different organs and tissues. Irisin, a myokine released in response to a high-fat diet and exercise, enhances GSIS. Similar to GLP-1, irisin augments insulin biosynthesis and promotes accrual of β-cell functional mass. In addition, irisin and GLP-1 share comparable pleiotropic effects and activate similar intracellular pathways. The insulinotropic and extra-pancreatic effects of GLP-1 are reduced in type 2 diabetes (T2D) patients but preserved at pharmacological doses. GLP-1 receptor agonists (GLP-1RAs) are therefore among the most widely used antidiabetes drugs, also considered for their cardiovascular benefits and ability to promote weight loss. Irisin levels are lower in T2D patients, and in diabetic and/or obese animal models irisin administration improves glycemic control and promotes weight loss. Interestingly, recent evidence suggests that both GLP-1 and irisin are also synthesized within the pancreatic islets, in α- and β-cells, respectively. This review aims to describe the similarities between GLP-1 and irisin and to propose a new potential axis-involving the gut, muscle, and endocrine pancreas that controls energy homeostasis.
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Affiliation(s)
| | | | | | | | | | | | - Francesco Giorgino
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; (N.M.); (G.B.); (A.B.); (A.C.); (S.P.); (L.L.); (A.N.)
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Madhu D, Khadir A, Hammad M, Kavalakatt S, Dehbi M, Al-Mulla F, Abubaker J, Tiss A. The GLP-1 analog exendin-4 modulates HSP72 expression and ERK1/2 activity in BTC6 mouse pancreatic cells. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140426. [DOI: 10.1016/j.bbapap.2020.140426] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/09/2020] [Accepted: 04/02/2020] [Indexed: 12/25/2022]
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Wang W, Wu RD, Chen P, Xu XJ, Shi XZ, Huang LH, Shao ZL, Guo W. Liraglutide combined with human umbilical cord mesenchymal stem cell transplantation inhibits beta-cell apoptosis via mediating the ASK1/JNK/BAX pathway in rats with type 2 diabetes. Diabetes Metab Res Rev 2020; 36:e3212. [PMID: 31411368 DOI: 10.1002/dmrr.3212] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 06/15/2019] [Accepted: 08/09/2019] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Accumulating evidence suggests an association between beta-cell apoptosis and the ASK1/JNK/BAX pathway. The aim of this study was to investigate the effects of a combined therapy of liraglutide and human umbilical cord mesenchymal stem cells (hUC-MSCs) on the glucose metabolism and islet beta-cell apoptosis, and further explore its relationship to the ASK1/JNK/BAX pathway. METHOD Type 2 diabetes mellitus (T2DM) rat model was induced by a high-sugar and high-fat diet and intraperitoneal injection of low-dose streptozotocin (STZ) (30 mg/kg). Three days after STZ injection, diabetic rats were randomly treated with subcutaneous injection of liraglutide (200 μg/kg/12 h) for 8 weeks and or hUC-MSCs (1 × 106 /rat) at the first and fifth weeks. Diabetes-related physical and biochemical parameters, pancreatic histopathological changes, immunohistochemical staining, quantitative real-time polymerase chain reaction, and western blot were used to measure the expression of apoptosis signal-regulating kinase 1 (ASK1), Jun N-terminal kinase (JNK), Bcl-2 associated X protein (BAX), and B-cell lymphoma-2 (Bcl-2). RESULTS Eight weeks after liraglutide or human umbilical cord mesenchymal stem cell administration, FPG, HbA1c , glucagon, body weight, and pancreatic ASK1, JNK, and BAX mRNA and proteins were significantly decreased, and the levels of serum C-p, INS and GLP-1, ratio of insulin positive area, and Bcl-2 expression were significantly increased in three treatment groups compared with T2DM group (P<.05). CONCLUSION Liraglutide combined with hUC-MSCs improve glucose metabolism and inhibit islet beta-cell apoptosis in a ASK1/JNK/BAX pathway-dependent manner.
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Affiliation(s)
- Wei Wang
- Fuzong Clinical Medical College, Fujian Medical University, Fuzhou, China
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
| | - Rong Dan Wu
- Fuzong Clinical Medical College, Fujian Medical University, Fuzhou, China
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
| | - Pin Chen
- Fuzong Clinical Medical College, Fujian Medical University, Fuzhou, China
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
| | - Xiang Jin Xu
- Fuzong Clinical Medical College, Fujian Medical University, Fuzhou, China
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
| | - Xiao Zhi Shi
- Fuzong Clinical Medical College, Fujian Medical University, Fuzhou, China
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
| | - Li Hong Huang
- Fuzong Clinical Medical College, Fujian Medical University, Fuzhou, China
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
| | - Zhu Lin Shao
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
| | - Wen Guo
- Department of Endocrinology, Fuzhou General Hospital, Fuzhou, China
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Madhu D, Hammad M, Kavalakatt S, Khadir A, Tiss A. GLP-1 Analogue, Exendin-4, Modulates MAPKs Activity but not the Heat Shock Response in Human HepG2 Cells. Proteomics Clin Appl 2017; 12. [PMID: 29105359 DOI: 10.1002/prca.201600169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 09/17/2017] [Indexed: 02/04/2023]
Abstract
PURPOSE Glucagon-like peptide-1 (GLP-1) analogues reduce ER stress and inflammation in key metabolic organs, including the liver. However, their effects on heat shock response (HSR) and mitogen-activated protein kinases (MAPKs) have not yet been elucidated. In the present study, we investigate whether the GLP-1 analogue, exendin-4, triggers the expression of HSR and increases MAPK activity under metabolic stress. EXPERIMENTAL DESIGN The effects of exendin-4 in the presence or absence of palmitic acid (PA; 400 μm) or glucose (30 mm) in the HepG2 liver cell line are assessed using Western blots, quantitative real-time PCR, and label-free proteomics. RESULTS Heat shock proteins (HSP60, HSP72, HSP90, and GRP78) and other chaperones are not significantly affected by exendin-4 under the conditions tested. In contrast, the presence of exendin-4 alone increases the MAPK phosphorylation levels (JNK, ERK1/2, and p38). For short incubation periods, in the presence of PA or glucose, treatment with exendin-4 exhibits limited effects but significantly attenuates MAPK phosphorylation after a 24-h incubation. Interestingly, canonical signaling pathways, such as EIF2, ILK, PKA, and Rho, are modulated by exendin-4. CONCLUSION AND CLINICAL RELEVANCE Identifying new pathways modulated by GLP-1 analogues will provide further insights into their benefits beyond their currently recognized roles in glycemic control, such as MAPK activity, energy homeostasis, and body weight decrease.
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Affiliation(s)
- Dhanya Madhu
- Research Division, Functional Proteomics and Metabolomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Maha Hammad
- Research Division, Functional Proteomics and Metabolomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Sina Kavalakatt
- Research Division, Functional Proteomics and Metabolomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Abdelkrim Khadir
- Research Division, Functional Proteomics and Metabolomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Ali Tiss
- Research Division, Functional Proteomics and Metabolomics Unit, Dasman Diabetes Institute, Kuwait City, Kuwait
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Muscogiuri G, Balercia G, Barrea L, Cignarelli A, Giorgino F, Holst JJ, Laudisio D, Orio F, Tirabassi G, Colao A. Gut: A key player in the pathogenesis of type 2 diabetes? Crit Rev Food Sci Nutr 2017; 58:1294-1309. [PMID: 27892685 DOI: 10.1080/10408398.2016.1252712] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The gut regulates glucose and energy homeostasis; thus, the presence of ingested nutrients into the gut activates sensing mechanisms that affect both glucose homeostasis and regulate food intake. Increasing evidence suggest that gut may also play a key role in the pathogenesis of type 2 diabetes which may be related to both the intestinal microbiological profile and patterns of gut hormones secretion. Intestinal microbiota includes trillions of microorganisms but its composition and function may be adversely affected in type 2 diabetes. The intestinal microbiota may be responsible of the secretion of molecules that may impair insulin secretion/action. At the same time, intestinal milieu regulates the secretion of hormones such as GLP-1, GIP, ghrelin, gastrin, somatostatin, CCK, serotonin, peptide YY, GLP-2, all of which importantly influence metabolism in general and in particular glucose metabolism. Thus, the aim of this paper is to review the current evidence on the role of the gut in the pathogenesis of type 2 diabetes, taking into account both hormonal and microbiological aspects.
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Affiliation(s)
| | - Giancarlo Balercia
- b Division of Endocrinology, Department of Clinical and Molecular Sciences , Umberto I Hospital, Polytechnic University of Marche , Ancona , Italy
| | | | - Angelo Cignarelli
- c Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases , University of Bari Aldo Moro , Bari , Italy
| | - Francesco Giorgino
- c Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases , University of Bari Aldo Moro , Bari , Italy
| | - Jens J Holst
- d NNF Center for Basic Metabolic Research and Department of Biomedical Sciences , Panum Institute, University of Copenhagen, Copenhagen , Denmark
| | | | - Francesco Orio
- e Endocrinology, Department of Sports Science and Wellness , "Parthenope" University Naples , Naples , Italy
| | - Giacomo Tirabassi
- b Division of Endocrinology, Department of Clinical and Molecular Sciences , Umberto I Hospital, Polytechnic University of Marche , Ancona , Italy
| | - Annamaria Colao
- f Department of Clinical Medicine and Surgery , "Federico II" University of Naples , Naples , Italy
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Oh YS, Seo E, Park K, Jun HS. Compound 19e, a Novel Glucokinase Activator, Protects against Cytokine-Induced Beta-Cell Apoptosis in INS-1 Cells. Front Pharmacol 2017; 8:169. [PMID: 28405188 PMCID: PMC5370240 DOI: 10.3389/fphar.2017.00169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 03/14/2017] [Indexed: 01/28/2023] Open
Abstract
Previously, compound 19e, a novel heteroaryl-containing benzamide derivative, was identified as a potent glucokinase activator (GKA) and showed a glucose-lowering effect in diabetic mice. In this study, the anti-apoptotic actions of 19e were evaluated in INS-1 pancreatic beta-cells co-treated with TNF-α and IL-1β to induce cell death. Compound 19e protected INS-1 cells from cytokine-induced cell death, and the effect was similar to treatment with another GKA or exendin-4. Compound 19e reduced annexin-V stained cells and the expression of cleaved caspase-3 and poly (ADP-ribose) polymerase protein, as well as upregulated the expression of B-cell lymphoma-2 protein. Compound 19e inhibited apoptotic signaling via induction of the ATP content, and the effect was correlated with the downregulation of nuclear factor-κB p65 and inducible nitric oxide synthase. Further, 19e increased NAD-dependent protein deacetylase sirtuin-1 (SIRT1) deacetylase activity, and the anti-apoptotic effect of 19e was attenuated by SIRT1 inhibitor or SIRT1 siRNA treatment. Our results demonstrate that the novel GKA, 19e, prevents cytokine-induced beta-cell apoptosis via SIRT1 activation and has potential as a therapeutic drug for the preservation of pancreatic beta-cells.
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Affiliation(s)
- Yoon Sin Oh
- College of Medicine, Lee Gil Ya Cancer and Diabetes Institute, Gachon UniversityIncheon, South Korea; Gachon Medical Research Institute, Gil HospitalIncheon, South Korea; Department of Food and Nutrition, Eulji UniversitySeongnam, South Korea
| | - Eunhui Seo
- College of Medicine, Lee Gil Ya Cancer and Diabetes Institute, Gachon University Incheon, South Korea
| | - Kaapjoo Park
- Yuhan Research Institute Gyeonggi-do, South Korea
| | - Hee-Sook Jun
- College of Medicine, Lee Gil Ya Cancer and Diabetes Institute, Gachon UniversityIncheon, South Korea; Gachon Medical Research Institute, Gil HospitalIncheon, South Korea; College of Pharmacy and Gachon Institute of Pharmaceutical Science, Gachon UniversityIncheon, South Korea
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12
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Takii M, Kaneko YK, Akiyama K, Aoyagi Y, Tara Y, Asakawa T, Inai M, Kan T, Nemoto K, Ishikawa T. Insulinotropic and anti-apoptotic effects of nobiletin in INS-1D β-cells. J Funct Foods 2017. [DOI: 10.1016/j.jff.2016.12.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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13
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Giorgino F, Bonadonna RC, Gentile S, Vettor R, Pozzilli P. Treatment intensification in patients with inadequate glycemic control on basal insulin: rationale and clinical evidence for the use of short-acting and other glucagon-like peptide-1 receptor agonists. Diabetes Metab Res Rev 2016; 32:497-511. [PMID: 26787264 PMCID: PMC5071744 DOI: 10.1002/dmrr.2775] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 12/07/2015] [Accepted: 12/18/2015] [Indexed: 12/17/2022]
Abstract
A substantial proportion of patients with type 2 diabetes mellitus do not reach glycemic targets, despite treatment with oral anti-diabetic drugs and basal insulin therapy. Several options exist for treatment intensification beyond basal insulin, and the treatment paradigm is complex. In this review, the options for treatment intensification will be explored, focusing on drug classes that act via the incretin system and paying particular attention to the short-acting glucagon-like peptide-1 receptor agonists exenatide and lixisenatide. Current treatment guidelines will be summarized and discussed. © 2016 The Authors. Diabetes/Metabolism Research and Reviews Published by John Wiley & Sons Ltd.
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Affiliation(s)
- Francesco Giorgino
- Dipartimento dell'Emergenza e dei Trapianti di Organi, Sezione di Medicina Interna, Endocrinologia, Andrologia e Malattie MetabolicheUniversità degli Studi di Bari Aldo MoroBariItaly
| | - Riccardo C. Bonadonna
- Dipartimento di Medicina Clinica e Sperimentale, Divisione di EndocrinologiaUniversità degli Studi di Parma, and AOU di ParmaParmaItaly
| | - Sandro Gentile
- Dipartimento di Medicina Clinica e SperimentaleSeconda Università degli Studi di NapoliNaplesItaly
| | - Roberto Vettor
- Dipartimento di Medicina – DIMED, Clinica Medica 3Università di PadovaPadovaItaly
| | - Paolo Pozzilli
- Department of Endocrinology & DiabetesUniversità Campus Bio‐MedicoRomeItaly
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14
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Natalicchio A, Biondi G, Marrano N, Labarbuta R, Tortosa F, Spagnuolo R, D'Oria R, Carchia E, Leonardini A, Cignarelli A, Perrini S, Laviola L, Giorgino F. Long-Term Exposure of Pancreatic β-Cells to Palmitate Results in SREBP-1C-Dependent Decreases in GLP-1 Receptor Signaling via CREB and AKT and Insulin Secretory Response. Endocrinology 2016; 157:2243-58. [PMID: 27035653 DOI: 10.1210/en.2015-2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effects of prolonged exposure of pancreatic β-cells to high saturated fatty acids on glucagon-like peptide-1 (GLP-1) action were investigated. Murine islets, human pancreatic 1.1B4 cells, and rat INS-1E cells were exposed to palmitate for 24 hours. mRNA and protein expression/phosphorylation were measured by real-time RT-PCR and immunoblotting, respectively. Specific short interfering RNAs were used to knockdown expression of the GLP-1 receptor (Glp1r) and Srebf1. Insulin release was assessed with a specific ELISA. Exposure of murine islets, as well as of human and INS-1E β-cells, to palmitate reduced the ability of exendin-4 to augment insulin mRNA levels, protein content, and release. In addition, palmitate blocked exendin-4-stimulated cAMP-response element-binding protein and v-akt murine thymoma viral oncogene homolog phosphorylation, whereas phosphorylation of MAPK-ERK kinase-1/2 and ERK-1/2 was not altered. Similarly, RNA interference-mediated suppression of Glp1r expression prevented exendin-4-induced cAMP-response element-binding protein and v-akt murine thymoma viral oncogene homolog phosphorylation, but did not impair exendin-4 stimulation of MAPK-ERK kinase-1/2 and ERK-1/2. Both islets from mice fed a high fat diet and human and INS-1E β-cells exposed to palmitate showed reduced GLP-1 receptor and pancreatic duodenal homeobox-1 (PDX-1) and increased sterol regulatory element-binding protein (SREBP-1C) mRNA and protein levels. Furthermore, suppression of SREBP-1C protein expression prevented the reduction of PDX-1 and GLP-1 receptor levels and restored exendin-4 signaling and action. Finally, treatment of INS-1E cells with metformin for 24 h resulted in inhibition of SREBP-1C expression, increased PDX-1 and GLP-1 receptor levels, consequently, enhancement of exendin-4-induced insulin release. Palmitate impairs exendin-4 effects on β-cells by reducing PDX-1 and GLP-1 receptor expression and signaling in a SREBP-1C-dependent manner. Metformin counteracts the impairment of GLP-1 receptor signaling induced by palmitate.
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Affiliation(s)
- Annalisa Natalicchio
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Giuseppina Biondi
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Nicola Marrano
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Rossella Labarbuta
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Federica Tortosa
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Rosaria Spagnuolo
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Rossella D'Oria
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Emanuele Carchia
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Anna Leonardini
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Angelo Cignarelli
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Sebastio Perrini
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Luigi Laviola
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
| | - Francesco Giorgino
- Department of Emergency and Organ Transplantation (A.N., G.B., N.M., R.L., F.T., R.S., R.D., A.L., A.C., S.P., L.L., F.G.), Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari Aldo Moro, I-70124 Bari, Italy; and IRGS Biogem (E.C.), I-83031 Ariano Irpino, Avellino, Italy
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15
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Wang J, Hu S, Wang J, Li S, Jiang W. Fucoidan from Acaudina molpadioides protects pancreatic islet against cell apoptosis via inhibition of inflammation in type 2 diabetic mice. Food Sci Biotechnol 2016; 25:293-300. [PMID: 30263270 DOI: 10.1007/s10068-016-0042-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/15/2015] [Accepted: 10/22/2015] [Indexed: 12/20/2022] Open
Abstract
Inflammation induces pancreatic islet cell apoptosis. Effects of fucoidan from Acaudina molpadioides (Am-FUC) on inhibition of pancreatic islet cell apoptosis and inflammation in type 2 diabetic mice were investigated. Am-FUC repaired pancreatic islet cells, decreased serum C-reactive protein (CRP), macrophage inflammatory protein 1 (MIP-1), interleukin 1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) levels, and increased the IL-10 level. Am-FUC also reduced TNF-α, CRP, MIP-1, IL-1β, and IL-6 mRNA expressions, and increased IL-10 mRNA expression in epididymal adipose tissues. Am-FUC reduced Bid, Bax, cytochrome c, caspase 9, and caspase 3 mRNA expressions, and increased Bcl-2 and Bcl-xL mRNA expressions. Am-FUC down-regulated t-Bid, Bax, cytochrome c, and caspase 9 activities, cleaved caspase 3 proteins, and up-regulated Bcl-2 and Bcl-xL proteins. Thus, an Am-FUCblocked mitochondrial pathway was the suppression mechanism in pancreatic islet cell apoptosis via regulation of inflammatory cytokines providing dietary intervention in type 2 diabetes and inflammation-induced pancreatic islet apoptosis.
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Affiliation(s)
- Jinhui Wang
- 1Innovation Application Institute, Zhejiang Ocean University, Zhoushan, 316022 China
| | - Shiwei Hu
- 1Innovation Application Institute, Zhejiang Ocean University, Zhoushan, 316022 China.,2College of Food Science and Engineering, Ocean University of China, Qingdao, 266003 China
| | - Jingfeng Wang
- 2College of Food Science and Engineering, Ocean University of China, Qingdao, 266003 China
| | - Shijie Li
- 1Innovation Application Institute, Zhejiang Ocean University, Zhoushan, 316022 China
| | - Wei Jiang
- 1Innovation Application Institute, Zhejiang Ocean University, Zhoushan, 316022 China.,2College of Food Science and Engineering, Ocean University of China, Qingdao, 266003 China
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16
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Yang TY, Yen CC, Lee KI, Su CC, Yang CY, Wu CC, Hsieh SS, Ueng KC, Huang CF. Molybdenum induces pancreatic β-cell dysfunction and apoptosis via interdependent of JNK and AMPK activation-regulated mitochondria-dependent and ER stress-triggered pathways. Toxicol Appl Pharmacol 2016; 294:54-64. [PMID: 26806093 DOI: 10.1016/j.taap.2016.01.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/29/2015] [Accepted: 01/19/2016] [Indexed: 12/25/2022]
Abstract
Molybdenum (Mo), a well-known toxic environmental and industrial pollutant, causes adverse health effects and diseases in humans and has received attention as a potential risk factor for DM. However, the roles of Mo in the mechanisms of the toxicological effects in pancreatic β-cells are mostly unclear. In this study, the results revealed dysfunction of insulin secretion and apoptosis in the pancreatic β-cell-derived RIN-m5F cells and the isolated mouse islets in response to Mo. These effects were accompanied by a mitochondria-dependent apoptotic signals including a decreased in the MMP, an increase in cytochrome c release, and the activation of caspase cascades and PARP. In addition, ER stress was triggered as indicated by several key molecules of the UPR. Furthermore, exposure to Mo induced the activation of ERK1/2, JNK, AMPKα, and GSK3-α/β. Pretreatment with specific pharmacological inhibitors (in RIN-m5F cells and isolated mouse islets) of JNK (SP600125) and AMPK (Compound C) or transfection with si-RNAs (in RIN-m5F cells) specific to JNK and AMPKα effectively prevented the Mo-induced apoptosis and related signals, but inhibitors of ERK1/2 and GSK3-α/β (PD98059 and LiCl, respectively) did not reverse the Mo-induced effects. Additionally, both the inhibitors and specific si-RNAs could suppress the Mo-induced phosphorylation of JNK and AMPKα each other. Taken together, these results suggest that Mo exerts its cytotoxicity on pancreatic β-cells by inducing dysfunction and apoptosis via interdependent JNK and AMPK activation downstream-regulated mitochondrial-dependent and ER stress-triggered apoptosis pathways.
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Affiliation(s)
- Tsung-Yuan Yang
- Institute of Medicine, Chung Shan Medical University, Taichung 402, Taiwan; Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan
| | - Cheng-Chieh Yen
- Department of Occupational Safety and Health, College of Health Care and Management, Chung Shan Medical University, Taichung 402, Taiwan; Department of Occupational Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan
| | - Kuan-I Lee
- Department of Emergency, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung 427, Taiwan
| | - Chin-Chuan Su
- Department of Otorhinolaryngology, Head and Neck Surgery, Changhua Christian Hospital, Changhua County 500, Taiwan; Graduate Institute of Basic Medical Science, School of Medicine, College of Medicine, China Medical University, Taichung 404, Taiwan
| | - Ching-Yao Yang
- Department of Surgery, National Taiwan University Hospital, Taipei 100, Taiwan; Department of Surgery, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Chin-Ching Wu
- Department of Public Health, China Medical University, Taichung 404, Taiwan
| | - Shang-Shu Hsieh
- Department of Emergency, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung 427, Taiwan.
| | - Kwo-Chang Ueng
- Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan; School of Medicine, Chung Shan Medical University, Taichung 402, Taiwan.
| | - Chun-Fa Huang
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung 404, Taiwan.
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17
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Baden MY, Fukui K, Hosokawa Y, Iwahashi H, Imagawa A, Shimomura I. Examination of a Viral Infection Mimetic Model in Human iPS Cell-Derived Insulin-Producing Cells and the Anti-Apoptotic Effect of GLP-1 Analogue. PLoS One 2015; 10:e0144606. [PMID: 26659307 PMCID: PMC4676675 DOI: 10.1371/journal.pone.0144606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/21/2015] [Indexed: 12/22/2022] Open
Abstract
Aims Viral infection is associated with pancreatic beta cell destruction in fulminant type 1 diabetes mellitus. The aim of this study was to investigate the acceleration and protective mechanisms of beta cell destruction by establishing a model of viral infection in pancreatic beta cells. Methods Polyinosinic:polycytidylic acid was transfected into MIN6 cells and insulin-producing cells differentiated from human induced pluripotent stem cells via small molecule applications. Gene expression was analyzed by real-time PCR, and apoptosis was evaluated by caspase-3 activity and TUNEL staining. The anti-apoptotic effect of Exendin-4 was also evaluated. Results Polyinosinic:polycytidylic acid transfection led to elevated expression of the genes encoding IFNα, IFNβ, CXCL10, Fas, viral receptors, and IFN-inducible antiviral effectors in MIN6 cells. Exendin-4 treatment suppressed the elevated gene expression levels and reduced polyinosinic:polycytidylic acid-induced apoptosis both in MIN6 cells and in insulin-producing cells from human induced pluripotent stem cells. Glucagon-like peptide-1 receptor, protein kinase A, and phosphatidylinositol-3 kinase inhibitors counteracted the anti-apoptotic effect of Exendin-4. Conclusions Polyinosinic:polycytidylic acid transfection can mimic viral infection, and Exendin-4 exerted an anti-apoptotic effect both in MIN6 and insulin-producing cells from human induced pluripotent stem cells.
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Affiliation(s)
- Megu Yamaguchi Baden
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Kenji Fukui
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Yoshiya Hosokawa
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Hiromi Iwahashi
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Akihisa Imagawa
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
- * E-mail:
| | - Iichiro Shimomura
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Suita, Japan
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18
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Fucosylated chondroitin sulfate from sea cucumber inhibited islets of langerhans apoptosis via inactivation of the mitochondrial pathway in insulin resistant mice. Food Sci Biotechnol 2015. [DOI: 10.1007/s10068-015-0141-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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19
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Natalicchio A, Tortosa F, Labarbuta R, Biondi G, Marrano N, Carchia E, Leonardini A, Cignarelli A, Bugliani M, Marchetti P, Fadini GP, Giorgio M, Avogaro A, Perrini S, Laviola L, Giorgino F. The p66(Shc) redox adaptor protein is induced by saturated fatty acids and mediates lipotoxicity-induced apoptosis in pancreatic beta cells. Diabetologia 2015; 58:1260-71. [PMID: 25810038 DOI: 10.1007/s00125-015-3563-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 02/27/2015] [Indexed: 01/03/2023]
Abstract
AIMS/HYPOTHESIS The role of the redox adaptor protein p66(Shc) as a potential mediator of saturated fatty acid (FA)-induced beta cell death was investigated. METHODS The effects of the FA palmitate on p66(Shc) expression were evaluated in human and murine islets and in rat insulin-secreting INS-1E cells. p66(Shc) expression was also measured in islets from mice fed a high-fat diet (HFD) and from human donors with different BMIs. Cell apoptosis was quantified by two independent assays. The role of p66(Shc) was investigated using pancreatic islets from p66 (Shc-/-) mice and in INS-1E cells with knockdown of p66(Shc) or overexpression of wild-type and phosphorylation-defective p66(Shc). Production of reactive oxygen species (ROS) was evaluated by the dihydroethidium oxidation method. RESULTS Palmitate induced a selective increase in p66(Shc) protein expression and phosphorylation on Ser(36) and augmented apoptosis in human and mouse islets and in INS-1E cells. Inhibiting the tumour suppressor protein p53 prevented both the palmitate-induced increase in p66(Shc) expression and beta cell apoptosis. Palmitate-induced apoptosis was abrogated in islets from p66 (Shc-/-) mice and following p66 (Shc) knockdown in INS-1E cells; by contrast, overexpression of p66(Shc), but not that of the phosphorylation-defective p66(Shc) mutant, enhanced palmitate-induced apoptosis. The pro-apoptotic effects of p66(Shc) were dependent upon its c-Jun N-terminal kinase-mediated phosphorylation on Ser(36) and associated with generation of ROS. p66(Shc) protein expression and function were also elevated in islets from HFD-fed mice and from obese/overweight cadaveric human donors. CONCLUSIONS/INTERPRETATION p53-dependent augmentation of p66(Shc) expression and function represents a key signalling response contributing to beta cell apoptosis under conditions of lipotoxicity.
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Affiliation(s)
- Annalisa Natalicchio
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
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20
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Blaabjerg L, Christensen GL, Matsumoto M, van der Meulen T, Huising MO, Billestrup N, Vale WW. CRFR1 activation protects against cytokine-induced β-cell death. J Mol Endocrinol 2014; 53:417-27. [PMID: 25324488 PMCID: PMC4518718 DOI: 10.1530/jme-14-0056] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
During the development of diabetes β-cells are exposed to elevated concentrations of proinflammatory cytokines, TNFα and IL1β, which in vitro induce β-cell death. The class B G-protein-coupled receptors (GPCRs): corticotropin-releasing factor receptor 1 (CRFR1) and CRFR2 are expressed in pancreatic islets. As downstream signaling by other class B GPCRs can protect against cytokine-induced β-cell apoptosis, we evaluated the protective potential of CRFR activation in β-cells in a pro-inflammatory setting. CRFR1/CRFR2 ligands activated AKT and CRFR1 signaling and reduced apoptosis in human islets. In rat and mouse insulin-secreting cell lines (INS-1 and MIN6), CRFR1 agonists upregulated insulin receptor substrate 2 (IRS2) expression, increased AKT activation, counteracted the cytokine-mediated decrease in BAD phosphorylation, and inhibited apoptosis. The anti-apoptotic signaling was dependent on prolonged exposure to corticotropin-releasing factor family peptides and followed PKA-mediated IRS2 upregulation. This indicates that CRFR signaling counteracts proinflammatory cytokine-mediated apoptotic pathways through upregulation of survival signaling in β-cells. Interestingly, CRFR signaling also counteracted basal apoptosis in both cultured INS-1 cells and intact human islets.
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Affiliation(s)
- Lykke Blaabjerg
- Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Gitte L Christensen
- Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Masahito Matsumoto
- Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Talitha van der Meulen
- Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Mark O Huising
- Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Nils Billestrup
- Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Wylie W Vale
- Clayton Foundation Laboratories for Peptide BiologySalk Institute, 10100 North Torrey Pines Road, La Jolla, California 92037, USACellular and Metabolic Research SectionDepartment of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
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21
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Shin S, Le Lay J, Everett LJ, Gupta R, Rafiq K, Kaestner KH. CREB mediates the insulinotropic and anti-apoptotic effects of GLP-1 signaling in adult mouse β-cells. Mol Metab 2014; 3:803-12. [PMID: 25379405 PMCID: PMC4216406 DOI: 10.1016/j.molmet.2014.08.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 08/12/2014] [Accepted: 08/15/2014] [Indexed: 12/27/2022] Open
Abstract
Objective Glucagon-like peptide-1 (GLP-1) plays a major role in pancreatic β-cell function and survival by increasing cytoplasmic cAMP levels, which are thought to affect transcription through activation of the basic leucine zipper (bZIP) transcription factor CREB. Here, we test CREB function in the adult β-cell through inducible gene deletion. Methods We employed cell type-specific and inducible gene ablation to determine CREB function in pancreatic β-cells in mice. Results By ablating CREB acutely in mature β-cells in tamoxifen-treated CrebloxP/loxP;Pdx1-CreERT2 mice, we show that CREB has little impact on β-cell turnover, in contrast to what had been postulated previously. Rather, CREB is required for GLP-1 to elicit its full effects on stimulating glucose-induced insulin secretion and protection from cytokine-induced apoptosis. Mechanistically, we find that CREB regulates expression of the pro-apoptotic gene p21 (Cdkn1a) in β-cells, thus demonstrating that CREB is essential to mediating this critical aspect of GLP-1 receptor signaling. Conclusions In sum, our studies using conditional gene deletion put into question current notions about the importance of CREB in regulating β-cell function and mass. However, we reveal an important role for CREB in the β-cell response to GLP-1 receptor signaling, further validating CREB as a therapeutic target for diabetes.
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Affiliation(s)
- Soona Shin
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - John Le Lay
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Logan J Everett
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Rana Gupta
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Kiran Rafiq
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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22
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Ogbourne SM, Parsons PG. The value of nature's natural product library for the discovery of New Chemical Entities: the discovery of ingenol mebutate. Fitoterapia 2014; 98:36-44. [PMID: 25016953 DOI: 10.1016/j.fitote.2014.07.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/03/2014] [Accepted: 07/04/2014] [Indexed: 11/15/2022]
Abstract
In recent decades, 'Big Pharma' has invested billions of dollars into ingenious and innovative strategies designed to develop drugs using high throughput screening of small molecule libraries generated on the laboratory bench. Within the same time frame, screening of natural products by pharmaceutical companies has suffered an equally significant reduction. This is despite the fact that the complexity, functional diversity and druggability of nature's natural product library are considered by many to be superior to any library any team of scientists can prepare. It is therefore no coincidence that the number of New Chemical Entities reaching the market has also suffered a substantial decrease, leading to a productivity crisis within the pharmaceutical sector. In fact, the current dearth of New Chemical Entities reaching the market in recent decades might be a direct consequence of the strategic decision to move away from screening of natural products. Nearly 700 novel drugs derived from natural product New Chemical Entities were approved between 1981 and 2010; more than 60% of all approved drugs over the same time. In this review, we use the example of ingenol mebutate, a natural product identified from Euphorbia peplus and later approved as a therapy for actinic keratosis, as why nature's natural product library remains the most valuable library for discovery of New Chemical Entities and of novel drug candidates.
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Affiliation(s)
- Steven M Ogbourne
- GeneCology Research Centre, Faculty of Science, Health, Engineering and Education, University of the Sunshine Coast, Maroochydore DC, QLD 4558, Australia.
| | - Peter G Parsons
- QIMR Berghofer Medical Research Institute, Locked Bag 2000, Post Office Royal Brisbane Hospital, QLD 4029, Australia.
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23
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Cunha DA, Gurzov EN, Naamane N, Ortis F, Cardozo AK, Bugliani M, Marchetti P, Eizirik DL, Cnop M. JunB protects β-cells from lipotoxicity via the XBP1-AKT pathway. Cell Death Differ 2014; 21:1313-24. [PMID: 24786832 DOI: 10.1038/cdd.2014.53] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 03/18/2014] [Accepted: 03/20/2014] [Indexed: 12/24/2022] Open
Abstract
Diets rich in saturated fats may contribute to the loss of pancreatic β-cells in type 2 diabetes. JunB, a member of the activating protein 1 (AP-1) transcription factor family, promotes β-cell survival and mediates part of the beneficial effects of GLP-1 agonists. In this study we interrogated the molecular mechanisms involved in JunB-mediated β-cell protection from lipotoxicity. The saturated fatty acid palmitate decreased JunB expression, and this loss may contribute to β-cell apoptosis, as overexpression of JunB protected cells from lipotoxicity. Array analysis of JunB-deficient β-cells identified a gene expression signature of a downregulated endoplasmic reticulum (ER) stress response and inhibited AKT signaling. JunB stimulates XBP1 expression via the transcription factor c/EBPδ during ER stress, and forced expression of XBP1s rescued the viability of JunB-deficient cells, constituting an important antiapoptotic mechanism. JunB silencing inhibited AKT activation and activated the proapoptotic Bcl-2 protein BAD via its dephosphorylation. BAD knockdown reversed lipotoxic β-cell death potentiated by JunB siRNA. Interestingly, XBP1s links JunB and AKT signaling as XBP1 knockdown also reduced AKT phosphorylation. GLP-1 agonists induced cAMP-dependent AKT phosphorylation leading to β-cell protection against palmitate-induced apoptosis. JunB and XBP1 knockdown or IRE1 inhibition decreased AKT activation by cAMP, leading to β-cell apoptosis. In conclusion, JunB modulates the β-cell ER stress response and AKT signaling via the induction of XBP1s. The activation of the JunB gene network and the crosstalk between the ER stress and AKT pathway constitute a crucial defense mechanism by which GLP-1 agonists protect against lipotoxic β-cell death. These findings elucidate novel β-cell-protective signal transduction in type 2 diabetes.
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Affiliation(s)
- D A Cunha
- Laboratory of Experimental Medicine and ULB Center of Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - E N Gurzov
- Laboratory of Experimental Medicine and ULB Center of Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - N Naamane
- Laboratory of Experimental Medicine and ULB Center of Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - F Ortis
- Laboratory of Experimental Medicine and ULB Center of Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - A K Cardozo
- Laboratory of Experimental Medicine and ULB Center of Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - M Bugliani
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
| | - P Marchetti
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
| | - D L Eizirik
- Laboratory of Experimental Medicine and ULB Center of Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - M Cnop
- 1] Laboratory of Experimental Medicine and ULB Center of Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium [2] Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
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24
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Marques C, Mega C, Gonçalves A, Rodrigues-Santos P, Teixeira-Lemos E, Teixeira F, Fontes-Ribeiro C, Reis F, Fernandes R. Sitagliptin prevents inflammation and apoptotic cell death in the kidney of type 2 diabetic animals. Mediators Inflamm 2014; 2014:538737. [PMID: 24817793 PMCID: PMC4000968 DOI: 10.1155/2014/538737] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 03/06/2014] [Accepted: 03/06/2014] [Indexed: 02/08/2023] Open
Abstract
This study aimed to evaluate the efficacy of sitagliptin, a dipeptidyl peptidase IV (DPP-IV) inhibitor, in preventing the deleterious effects of diabetes on the kidney in an animal model of type 2 diabetes mellitus; the Zucker diabetic fatty (ZDF) rat: 20-week-old rats were treated with sitagliptin (10 mg/kg bw/day) during 6 weeks. Glycaemia and blood HbA1c levels were monitored, as well as kidney function and lesions. Kidney mRNA and/or protein content/distribution of DPP-IV, GLP-1, GLP-1R, TNF-α, IL-1β, BAX, Bcl-2, and Bid were evaluated by RT-PCR and/or western blotting/immunohistochemistry. Sitagliptin treatment improved glycaemic control, as reflected by the significantly reduced levels of glycaemia and HbA1c (by about 22.5% and 1.2%, resp.) and ameliorated tubulointerstitial and glomerular lesions. Sitagliptin prevented the diabetes-induced increase in DPP-IV levels and the decrease in GLP-1 levels in kidney. Sitagliptin increased colocalization of GLP-1 and GLP-1R in the diabetic kidney. Sitagliptin also decreased IL-1β and TNF-α levels, as well as, prevented the increase of BAX/Bcl-2 ratio, Bid protein levels, and TUNEL-positive cells which indicates protective effects against inflammation and proapoptotic state in the kidney of diabetic rats, respectively. In conclusion, sitagliptin might have a major role in preventing diabetic nephropathy evolution due to anti-inflammatory and antiapoptotic properties.
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Affiliation(s)
- Catarina Marques
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Cristina Mega
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
- ESAV, Technologies and Health Study Center, Polytechnic Institute of Viseu, 3504-510 Viseu, Portugal
- Educational Technologies and Health Study Center, Polytechnic Institute of Viseu, 3504-510 Viseu, Portugal
| | - Andreia Gonçalves
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Paulo Rodrigues-Santos
- Institute of Immunology, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
- Immunology and Oncology Laboratory, CNC, 3004-517 Coimbra, Portugal
| | - Edite Teixeira-Lemos
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
- ESAV, Technologies and Health Study Center, Polytechnic Institute of Viseu, 3504-510 Viseu, Portugal
| | - Frederico Teixeira
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Carlos Fontes-Ribeiro
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Flávio Reis
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Rosa Fernandes
- Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
- Center of Ophthalmology and Vision Sciences, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
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25
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Hu S, Wang J, Xu H, Wang Y, Li Z, Xue C. Fucosylated chondroitin sulphate from sea cucumber inhibits high-fat-sucrose diet-induced apoptosis in mouse pancreatic islets via down-regulating mitochondrial signaling pathway. J Funct Foods 2014. [DOI: 10.1016/j.jff.2014.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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26
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Ezanno H, Pawlowski V, Abdelli S, Boutry R, Gmyr V, Kerr-Conte J, Bonny C, Pattou F, Abderrahmani A. JNK3 is required for the cytoprotective effect of exendin 4. J Diabetes Res 2014; 2014:814854. [PMID: 25025079 PMCID: PMC4083605 DOI: 10.1155/2014/814854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 05/13/2014] [Accepted: 05/27/2014] [Indexed: 12/26/2022] Open
Abstract
Preservation of beta cell against apoptosis is one of the therapeutic benefits of the glucagon-like peptide-1 (GLP1) antidiabetic mimetics for preserving the functional beta cell mass exposed to diabetogenic condition including proinflammatory cytokines. The mitogen activated protein kinase 10 also called c-jun amino-terminal kinase 3 (JNK3) plays a protective role in insulin-secreting cells against death caused by cytokines. In this study, we investigated whether the JNK3 expression is associated with the protective effect elicited by the GLP1 mimetic exendin 4. We found an increase in the abundance of JNK3 in isolated human islets and INS-1E cells cultured with exendin 4. Induction of JNK3 by exendin 4 was associated with an increased survival of INS-1E cells. Silencing of JNK3 prevented the cytoprotective effect of exendin 4 against apoptosis elicited by culture condition and cytokines. These results emphasize the requirement of JNK3 in the antiapoptotic effects of exendin 4.
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Affiliation(s)
- Hélène Ezanno
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
| | - Valérie Pawlowski
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Saida Abdelli
- Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, 1011 Lausanne, Switzerland
| | - Raphael Boutry
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
| | - Valery Gmyr
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Julie Kerr-Conte
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Christophe Bonny
- Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, 1011 Lausanne, Switzerland
| | - François Pattou
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
| | - Amar Abderrahmani
- Lille 2 University, University of Lille Nord de France, European Genomic Institute for Diabetes, EGID FR 3508, UMR 8199, Lille, France
- Department of Endocrine Surgery, Lille 2 University, University of Lille Nord de France, Lille University Hospital, INSERM UMR 859, Biotherapies for Diabetes, European Genomic Institute for Diabetes, Lille, France
- *Amar Abderrahmani:
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27
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Puyal J, Pétremand J, Dubuis G, Rummel C, Widmann C. HDLs protect the MIN6 insulinoma cell line against tunicamycin-induced apoptosis without inhibiting ER stress and without restoring ER functionality. Mol Cell Endocrinol 2013; 381:291-301. [PMID: 23994023 DOI: 10.1016/j.mce.2013.08.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 08/22/2013] [Accepted: 08/22/2013] [Indexed: 12/31/2022]
Abstract
HDLs protect pancreatic beta cells against apoptosis induced by several endoplasmic reticulum (ER) stressors, including thapsigargin, cyclopiazonic acid, palmitate and insulin over-expression. This protection is mediated by the capacity of HDLs to maintain proper ER morphology and ER functions such as protein folding and trafficking. Here, we identified a distinct mode of protection exerted by HDLs in beta cells challenged with tunicamycin (TM), a protein glycosylation inhibitor inducing ER stress. HDLs were found to inhibit apoptosis induced by TM in the MIN6 insulinoma cell line and this correlated with the maintenance of a normal ER morphology. Surprisingly however, this protective response was neither associated with a significant ER stress reduction, nor with restoration of protein folding and trafficking in the ER. These data indicate that HDLs can use at least two mechanisms to protect beta cells against ER stressors. One that relies on the maintenance of ER function and one that operates independently of ER function modulation. The capacity of HDLs to activate several anti-apoptotic pathways in beta cells may explain their ability to efficiently protect these cells against a variety of insults.
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Affiliation(s)
- Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland
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28
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Liu XH, Wang YP, Wang LX, Chen Z, Liu XY, Liu LB. Exendin-4 protects murine MIN6 pancreatic β-cells from interleukin-1β-induced apoptosis via the NF-κB pathway. J Endocrinol Invest 2013; 36:803-11. [PMID: 23609920 DOI: 10.3275/8938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Glucagon-like peptide-1 (GLP-1) and its potent analog, exendin-4, are well known to inhibit β- cell apoptosis and promote β-cell proliferation. Meanwhile, cytokines, such as interleukin-1β (IL-1β), stimulate inducible nitric oxide synthase (iNOS) expression and nitric oxide overproduction leading to β-cell damage. However, the protective mechanisms of GLP-1 in β-cells exposed to cytokines have not been fully elucidated. AIMS In this study, the protective effects of exendin-4 on IL-1β-induced apoptosis were investigated in murine MIN6 pancreatic β-cells. The role of nuclear factor-κB (NF-κB) signaling in this process was also explored. METHODS The effects of exendin-4 pre-treatment on IL-1β-induced apoptosis were investigated by Hoechst/PI and Annexin V/PI staining. Levels of iNOS and NF-κB proteins were investigated by Western blotting and cytoplasmic nitrite levels were determined using Griess reagent. RESULTS IL-1β treatment (range, 5-40 ng/ml) for 24 h was positively correlated with nitrite production (R2=0.9668, p<0.01), a significant increase in the percentage of apoptotic cells (p<0.01) and a concomitant dose-dependent increase in cytoplasmic levels of iNOS and NF-κB p65 activation. N-acetyl- L-cysteine (NAC), NG-nitro-L-arginine methyl ester (L-NAME) and pyrrolidine dithiocarbamate (PDTC), partially rescued apoptotic β-cells, suggesting involvement of NF-κB-iNOS-nitrite in this process. Exendin-4 (100 nM) treatment significantly decreased IL-1β-induced apoptosis (p<0.01), downregulated NF-κB activation and subsequently decreased iNOS and nitrite levels in IL-1β-induced β-cells (p<0.001), in a similar manner to L-NAME, PDTC and NAC. CONCLUSIONS These results suggest that exendin-4 protects against IL-1β- induced apoptosis in β-cells via downregulation of the NF- κB-iNOS-nitrite pathway.
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Affiliation(s)
- X H Liu
- Department of Endocrinology, Fujian Institute of Endocrinology, Union Hospital of Fujian Medical University, 29 Xinquan Road, Fuzhou, Fujian 350001, People's Republic of China
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29
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Natalicchio A, Labarbuta R, Tortosa F, Biondi G, Marrano N, Peschechera A, Carchia E, Orlando MR, Leonardini A, Cignarelli A, Marchetti P, Perrini S, Laviola L, Giorgino F. Exendin-4 protects pancreatic beta cells from palmitate-induced apoptosis by interfering with GPR40 and the MKK4/7 stress kinase signalling pathway. Diabetologia 2013; 56:2456-66. [PMID: 23995397 DOI: 10.1007/s00125-013-3028-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 07/29/2013] [Indexed: 12/24/2022]
Abstract
AIMS/HYPOTHESIS The mechanisms of the protective effects of exendin-4 on NEFA-induced beta cell apoptosis were investigated. METHODS The effects of exendin-4 and palmitate were evaluated in human and murine islets, rat insulin-secreting INS-1E cells and murine glucagon-secreting alpha-TC1-6 cells. mRNA and protein expression/phosphorylation were measured by real-time RT-PCR and immunoblotting or immunofluorescence, respectively. Small interfering (si)RNAs for Ib1 and Gpr40 were used. Cell apoptosis was quantified by two independent assays. Insulin release was assessed with an insulin ELISA. RESULTS Exposure of human and murine primary islets and INS-1E cells, but not alpha-TC1-6 cells, to exendin-4 inhibited phosphorylation of the stress kinases, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), and prevented apoptosis in response to palmitate. Exendin-4 increased the protein content of islet-brain 1 (IB1), an endogenous JNK blocker; however, siRNA-mediated reduction of IB1 did not impair the ability of exendin-4 to inhibit JNK and prevent apoptosis. Exendin-4 reduced G-protein-coupled receptor 40 (GPR40) expression and inhibited palmitate-induced phosphorylation of mitogen-activated kinase kinase (MKK)4 and MKK7. The effects of exendin-4 were abrogated in the presence of the protein kinase A (PKA) inhibitors, H89 and KT5720. Knockdown of GPR40, as well as use of a specific GPR40 antagonist, resulted in diminished palmitate-induced JNK and p38 MAPK phosphorylation and apoptosis. Furthermore, inhibition of JNK and p38 MAPK activity prevented palmitate-induced apoptosis. CONCLUSIONS/INTERPRETATION Exendin-4 counteracts the proapoptotic effects of palmitate in beta cells by reducing GPR40 expression and inhibiting MKK7- and MKK4-dependent phosphorylation of the stress kinases, JNK and p38 MAPK, in a PKA-dependent manner.
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Affiliation(s)
- Annalisa Natalicchio
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
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Opinto G, Natalicchio A, Marchetti P. Physiology of incretins and loss of incretin effect in type 2 diabetes and obesity. Arch Physiol Biochem 2013; 119:170-8. [PMID: 23859800 DOI: 10.3109/13813455.2013.812664] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
An important role in the regulation of glucose homeostasis is played by incretins, which are gut-derived hormones released in response to nutrient ingestion. In humans, the major incretin hormones are glucagon-like peptide (GLP)-1 and glucose-dependent insulinotropic polypeptide (GIP), and together they fully account for the incretin effect (that is, higher insulin release in response to an oral glucose challenge compared to an equal intravenous glucose load). Studies have shown that GLP-1 and GIP levels and actions may be perturbed in disease states, and the loss of incretin effect is likely to contribute importantly to the postprandial hyperglycaemia in type 2 diabetes. However, the specific cause-effect relationship between disease and incretins is still unclear. This review focuses on several key studies elucidating the association of defective incretin action with obesity and T2DM and the effects of metformin and other anti-diabetic agents on the incretin system.
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Affiliation(s)
- Giuseppina Opinto
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari School of Medicine , Bari , Italy and
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31
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Abstract
Pancreatic beta-cell mass expands through beta-cell proliferation and neogenesis while it decreases mainly via apoptosis. The loss of balance between beta-cell death and regeneration leads to a reduction of beta-cell functional mass, thus contributing to the pathogenesis of type 2 diabetes mellitus (T2DM). The pathogenetic mechanisms causing T2DM are complex, and also include a significant reduction of the incretin effect. A better understanding of the role of incretin hormones in glucose homeostasis has led to the development of incretin-based therapies. Recently, incretin hormones have been shown to stimulate the beta-cell growth and differentiation from pancreas-derived stem/progenitor cells, as well as to exert cytoprotective, antiapoptotic effects on beta-cells. However, the role and the molecular mechanisms by which GLP-1 and its agonists regulate beta-cell mass have not been fully investigated. This review focuses the current findings and the missing understanding of the effects of incretin hormones on beta-cell mass expansion.
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Affiliation(s)
- Federica Tortosa
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari School of Medicine , Bari , Italy and
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32
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Zhang L, Yang M, Ren H, Hu H, Boden G, Li L, Yang G. GLP-1 analogue prevents NAFLD in ApoE KO mice with diet and Acrp30 knockdown by inhibiting c-JNK. Liver Int 2013; 33:794-804. [PMID: 23432843 DOI: 10.1111/liv.12120] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 01/09/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Liraglutide, a Glucagon-like peptide-1(GLP-1) analogue with 97% sequence identity to human GLP-1, increases insulin secretion and insulin sensitivity. Its effect on non-alcoholic fatty liver disease (NAFLD) remains poorly understood. In this study, we examined whether liraglutide can protect against inflammatory stress by inhibiting activation of c-Jun N-terminal protein kinase (JNK). METHODS ApoE KO and adiponectin (Acrp30) knockdown mice fed a high-fat diet (HFD) were treated with liraglutide (1 mg/kg, twice daily) for 8 weeks. Liver tissue was procured for histological examination, real-time RT-PCR and Western blot analysis. RESULTS The results showed that the combination of HFD, Acrp30 knockdown and ApoE deficiency had additive effects on the development of insulin resistance (IR) and NAFLD. Administration of liraglutide prevented the development of HFD and hypoadiponectinaemia-induced IR and NAFLD in this model. Liraglutide also attenuated the expression of proinflammatory cytokines or transcription factor, including TNF-α and NF-κB(65) , and the expression of two lipogenesis-related genes, Acetyl-CoA Carboxylase (ACC) and fatty acid synthase (FAS). These changes were accompanied by elevated plasma of Acrp30, increased Acrp30 mRNA, AMP Kinase phosphorylation, and decreased mitogen-activated protein kinase 4 (MKK4) mRNA expression and JNK phosphorylation. CONCLUSIONS Our study also showed potent inhibitory effects of liraglutide on MKK4/JNK signalling which may be a mechanism for the observed improved insulin sensitivity and inflammatory stress induced by HFD and hypoadiponectinaemia.
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Affiliation(s)
- Lili Zhang
- Department of Endocrinology, the Second Affiliated Hospital, Chongqing Medical University, Chongqing, China
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Laviola L, Leonardini A, Melchiorre M, Orlando MR, Peschechera A, Bortone A, Paparella D, Natalicchio A, Perrini S, Giorgino F. Glucagon-like peptide-1 counteracts oxidative stress-dependent apoptosis of human cardiac progenitor cells by inhibiting the activation of the c-Jun N-terminal protein kinase signaling pathway. Endocrinology 2012; 153:5770-81. [PMID: 23077074 DOI: 10.1210/en.2012-1461] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Increased apoptosis of cardiac progenitor cells (CPCs) has been proposed as a mechanism of myocardial damage and dysfunction. Glucagon-like peptide-1 (GLP-1) has been shown to improve heart recovery and function after ischemia and to promote cell survival. The protective effects of GLP-1 on oxidative stress-induced apoptosis were investigated in human CPCs isolated from human heart biopsies. Mesenchymal-type cells were isolated from human heart biopsies, exhibited the marker profile of CPCs, differentiated toward the myocardiocyte, adipocyte, chondrocyte, and osteocyte lineages under appropriate culture conditions, and expressed functional GLP-1 receptors. CPCs were incubated with GLP-1 with or without hydrogen peroxide (H(2)O(2)). Phospho- and total proteins were detected by immunoblotting and immunofluorescence analysis. Gene expression was evaluated by quantitative RT-PCR. The role of the canonical GLP-1 receptor was assessed by using the receptor antagonist exendin(9-39) and receptor-specific silencer small interfering RNAs. Cell apoptosis was quantified by an ELISA assay and by flow cytometry-detected Annexin V. Exposure of CPCs to H(2)O(2) induced a 2-fold increase in cell apoptosis, mediated by activation of the c-Jun N-terminal protein kinase (JNK) pathway. Preincubation of CPCs with GLP-1 avoided H(2)O(2)-triggered JNK phosphorylation and nuclear localization, and protected CPCs from apoptosis. The GLP-1 effects were markedly reduced by coincubation with the receptor antagonist exendin(9-39), small interfering RNA-mediated silencing of the GLP-1 receptor, and pretreatment with the protein kinase A inhibitor H89. In conclusion, activation of GLP-1 receptors prevents oxidative stress-mediated apoptosis in human CPCs by interfering with JNK activation and may represent an important mechanism for the cardioprotective effects of GLP-1.
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Affiliation(s)
- L Laviola
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, I-70124 Bari, Italy
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Zhan Y, Sun HL, Chen H, Zhang H, Sun J, Zhang Z, Cai DH. Glucagon-like peptide-1 (GLP-1) protects vascular endothelial cells against advanced glycation end products (AGEs)-induced apoptosis. Med Sci Monit 2012; 18:BR286-91. [PMID: 22739729 PMCID: PMC3560786 DOI: 10.12659/msm.883207] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Background The peptide glucagon-like peptide-1 (GLP-1) is a hormone secreted by intestinal L cells in response to food intake. GLP-1 has been proposed as the basis of emerging therapy for patients with type 2 diabetes. However, the effects of GLP-1 on vascular injury in diabetes have not been identified. Advanced glycation end products (AGEs) induce endothelial cell apoptosis and have been implicated in the process of vascular complications from diabetes. Material/Methods The aim of this work was to investigate whether and how GLP-1 protects endothelial cells from apoptosis induced by AGEs. Human umbilical vein endothelial cells (HUVECs) were treated with AGEs (200 μg/mL) for 48 h in the presence or absence of GLP-1. Cell morphology, viability, apoptosis, ratio of Bcl-2 protein to Bax protein, cytochrome c release, and activity of caspase-9 and −3 were determined. Results Treatment of cells with AGEs led to cell morphology changes and decreased cell viability, resulting in apoptosis. GLP-1 alone increased cell viability in a concentration-dependent manner. GLP-1 partially inhibited AGEs-induced apoptosis in HUVECs. GLP-1 increased Bcl-2/Bax ratio, reduced cytochrome c levels in the cytoplasm, and reduced the activity of caspase-9 and −3 in AGEs-treated HUVECs. Conclusions AGEs induces apoptosis via the mitochondrion-cytochrome c-caspase protease pathway, and GLP-1 protects endothelial cells by interfering with this mechanism. GLP-1 may represent an anti-apoptotic agent in the treatment of vascular complications arising from diabetes.
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Affiliation(s)
- Yi Zhan
- Department of Endocrinology, Zhujiang Hospital, Southern Medical University, Guangzhou, China
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Plomgaard P, Halban PA, Bouzakri K. Bimodal impact of skeletal muscle on pancreatic β-cell function in health and disease. Diabetes Obes Metab 2012; 14 Suppl 3:78-84. [PMID: 22928567 DOI: 10.1111/j.1463-1326.2012.01641.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Diabetes is a complex disease that affects many organs directly or indirectly. Type 2 diabetes mellitus is characterized by insulin resistance with a relative deficiency in insulin secretion. It has become apparent that inter-organ communication is of great importance in the pathophysiology of diabetes. Far from being an inert tissue in terms of inter-organ communication, it is now recognized that skeletal muscle can secrete so-called myokines that can impact on the function of distant organs/tissues both favourably and unfavourably. We have proposed that communication between insulin-resistant skeletal muscle and β-cells occurs in diabetes. This is a novel route of communication that we further suggest is modified by the prevailing degree of insulin resistance of skeletal muscle. This review focuses on the various myokines [interleukin-6 (IL-6), tumor necrosis factor-α, CXCL10, follistatin and IL-8] which have been identified either after different types of exercise or in the secretome from control and insulin-resistant human skeletal myotubes. We will also summarize studies on the impact of several myokines on pancreatic β-cell proliferation, survival and function.
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Affiliation(s)
- P Plomgaard
- The Centre of Inflammation and Metabolism, Department of Infectious Diseases, Rigshospitalet, Faculty of Health Sciences, Copenhagen, Denmark
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Wang MD, Huang Y, Zhang GP, Mao L, Xia YP, Mei YW, Hu B. Exendin-4 improved rat cortical neuron survival under oxygen/glucose deprivation through PKA pathway. Neuroscience 2012; 226:388-96. [PMID: 23000625 DOI: 10.1016/j.neuroscience.2012.09.025] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 09/01/2012] [Accepted: 09/11/2012] [Indexed: 12/17/2022]
Abstract
Previous studies demonstrated that exendin-4 (Ex-4) may possess neurotrophic and neuroprotective functions in ischemia insults, but its mechanism remained unknown. Here, by using real-time PCR and ELISA, we identified the distribution of active GLP-1Rs in the rat primary cortical neurons. After establishment of an in vitro ischemia model by oxygen/glucose deprivation (OGD), neurons were treated with various dosages of Ex-4. The MTT assay showed that the relative survival rate increased with the dosage of Ex-4 ranging from 0.2 to 0.8 μg/ml (P<0.001, vs. OGD group). The apoptosis rate was reduced from (49.47±2.70)% to (14.61±0.81)% after Ex-4 treatment (0.4 μg/ml) 12h after OGD (P<0.001). Moreover, immunofluorescence staining indicated that Ex-4 increased glucose-regulated proteins 78 (GRP78) and reduced C/EBP-homologous protein (CHOP). Western blot analysis demonstrated that, after neurons were treated with Ex-4, GRP78 was up-regulated over time (P<0.01, vs. OGD group), while CHOP levels rose to a peak 8h after OGD and then decreased (P<0.05, vs. OGD group). This effect was changed by both the protein kinase A (PKA) inhibitor H89 (P<0.01, P<0.05, respectively, vs. Ex-4 group) and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 (P<0.01, P<0.01, respectively, vs. Ex-4 group) but not by the mitogen-activated protein kinase (MAPK) inhibitor U0126. Our study also revealed that, compared with the Ex-4 group, inhibition of the PKA signaling pathway significantly decreased the survival rate of neurons, down-regulated the expression of B-cell lymphoma 2 (Bcl-2) and up-regulated the Bax expression 3h after ODG (P<0.05, P<0.01, respectively), while neither PI3K nor MAPK inhibition exerted such effects. Furthermore, Western blotting exhibited that PKA expression was elevated in the presence or absence of OGD insults (P<0.05). This study indicated that Ex-4 protected neurons against OGD by modulating the unfolded protein response (UPR) through the PKA pathway and may serve as a novel therapeutic agent for stroke.
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Affiliation(s)
- M-D Wang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Avenue, Wuhan 430022, PR China
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Clark I, Atwood C, Bowen R, Paz-Filho G, Vissel B. Tumor necrosis factor-induced cerebral insulin resistance in Alzheimer's disease links numerous treatment rationales. Pharmacol Rev 2012; 64:1004-26. [PMID: 22966039 DOI: 10.1124/pr.112.005850] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The evident limitations of the amyloid theory of the pathogenesis of Alzheimer's disease are increasingly putting alternatives in the spotlight. We argue here that a number of independently developing approaches to therapy-including specific and nonspecific anti-tumor necrosis factor (TNF) agents, apolipoprotein E mimetics, leptin, intranasal insulin, the glucagon-like peptide-1 mimetics and glycogen synthase kinase-3 (GSK-3) antagonists-are all part of an interlocking chain of events. All these approaches inform us that inflammation and thence cerebral insulin resistance constitute the pathway on which to focus for a successful clinical outcome in treating this disease. The key link in this chain presently absent is a recognition by Alzheimer's research community of the long-neglected history of TNF induction of insulin resistance. When this is incorporated into the bigger picture, it becomes evident that the interventions we discuss are not competing alternatives but equally valid approaches to correcting different parts of the same pathway to Alzheimer's disease. These treatments can be expected to be at least additive, and conceivably synergistic, in effect. Thus the inflammation, insulin resistance, GSK-3, and mitochondrial dysfunction hypotheses are not opposing ideas but stages of the same fundamental, overarching, pathway of Alzheimer's disease pathogenesis. The insight this provides into progenitor cells, including those involved in adult neurogenesis, is a key part of this approach. This pathway also has therapeutic implications for other circumstances in which brain TNF is pathologically increased, such as stroke, traumatic brain injury, and the infectious disease encephalopathies.
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Affiliation(s)
- Ian Clark
- Division of Medical Science and Biochemistry, Research School of Biology, Australian National University, Canberra ACT, Australia.
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38
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Bomfim TR, Forny-Germano L, Sathler LB, Brito-Moreira J, Houzel JC, Decker H, Silverman MA, Kazi H, Melo HM, McClean PL, Holscher C, Arnold SE, Talbot K, Klein WL, Munoz DP, Ferreira ST, De Felice FG. An anti-diabetes agent protects the mouse brain from defective insulin signaling caused by Alzheimer's disease- associated Aβ oligomers. J Clin Invest 2012; 122:1339-53. [PMID: 22476196 DOI: 10.1172/jci57256] [Citation(s) in RCA: 636] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 01/05/2012] [Indexed: 02/06/2023] Open
Abstract
Defective brain insulin signaling has been suggested to contribute to the cognitive deficits in patients with Alzheimer's disease (AD). Although a connection between AD and diabetes has been suggested, a major unknown is the mechanism(s) by which insulin resistance in the brain arises in individuals with AD. Here, we show that serine phosphorylation of IRS-1 (IRS-1pSer) is common to both diseases. Brain tissue from humans with AD had elevated levels of IRS-1pSer and activated JNK, analogous to what occurs in peripheral tissue in patients with diabetes. We found that amyloid-β peptide (Aβ) oligomers, synaptotoxins that accumulate in the brains of AD patients, activated the JNK/TNF-α pathway, induced IRS-1 phosphorylation at multiple serine residues, and inhibited physiological IRS-1pTyr in mature cultured hippocampal neurons. Impaired IRS-1 signaling was also present in the hippocampi of Tg mice with a brain condition that models AD. Importantly, intracerebroventricular injection of Aβ oligomers triggered hippocampal IRS-1pSer and JNK activation in cynomolgus monkeys. The oligomer-induced neuronal pathologies observed in vitro, including impaired axonal transport, were prevented by exposure to exendin-4 (exenatide), an anti-diabetes agent. In Tg mice, exendin-4 decreased levels of hippocampal IRS-1pSer and activated JNK and improved behavioral measures of cognition. By establishing molecular links between the dysregulated insulin signaling in AD and diabetes, our results open avenues for the investigation of new therapeutics in AD.
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Affiliation(s)
- Theresa R Bomfim
- Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
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Hu QH, Zhang X, Pan Y, Li YC, Kong LD. Allopurinol, quercetin and rutin ameliorate renal NLRP3 inflammasome activation and lipid accumulation in fructose-fed rats. Biochem Pharmacol 2012; 84:113-25. [DOI: 10.1016/j.bcp.2012.03.005] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 03/08/2012] [Accepted: 03/08/2012] [Indexed: 12/24/2022]
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40
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Lin CY, Ni CC, Yin MC, Lii CK. Flavonoids protect pancreatic beta-cells from cytokines mediated apoptosis through the activation of PI3-kinase pathway. Cytokine 2012; 59:65-71. [DOI: 10.1016/j.cyto.2012.04.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 01/10/2012] [Accepted: 04/11/2012] [Indexed: 12/31/2022]
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41
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Wang Y, Dong W, Ding X, Wang F, Wang Y, Chen X, Yu L, Li X, Zhang A, Peng Y. Protective effect of α-lipoic acid on islet cells co-cultured with 3T3L1 adipocytes. Exp Ther Med 2012. [PMID: 23181120 PMCID: PMC3503631 DOI: 10.3892/etm.2012.601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Obesity and β-cell dysfunction due to oxidative stress impact the pathogenesis of type 2 diabetes mellitus. We co-cultured 3T3L1 adipocytes and islet cells in the presence or absence of the antioxidant α-lipoic acid (LA) and assayed the effects of the adipocytes and LA on the secretion of insulin by the islet cells and on the activities of factors involved in secretion and oxidative stress. At low glucose concentrations (2.8 mmol/l), the presence of adipocytes (co-culture) increased insulin secretion compared with islet cells cultured alone (control) and this increase was diminished by LA (co-culture plus LA). At high glucose concentrations (22 mmol/l), insulin secretion levels were similar for all islet groups, resulting in a restoration of the stimulation index in the presence of LA. The mRNA levels of the glucose-stimulated insulin secretion (GSIS) genes glucokinase, glucose transporter 2 and Kir6.2 were downregulated under co-culture and co-culture plus LA conditions. Protein and tyrosine phosphorylation levels of insulin receptor-β and insulin receptor substrate-1 were decreased under co-culture conditions and were restored by LA treatment. Cellular malondialdehyde levels increased in the co-cultured islets and this increase was blocked by LA. The mRNA levels of superoxide dismutase and catalase were reduced under co-culture conditions and these reductions were eliminated by the addition of LA. In conclusion, 3T3L1 adipocytes disturb insulin secretion and induce islet dysfunction. The effects may be mediated by multiple pathways, which include downregulation of GSIS gene expression, suppression of islet cell insulin signaling and the induction of oxidative stress. LA may protect islet cells via activation of islet cell insulin signaling and the mRNA expression of antioxidant enzymes.
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Affiliation(s)
- Yufan Wang
- Department of Endocrinology and Metabolism
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42
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Jeong JH, Yook S, Jung Y, Im BH, Lee M, Ahn CH, Lee DY, Byun Y. Functional enhancement of beta cells in transplanted pancreatic islets by secretion signal peptide-linked exendin-4 gene transduction. J Control Release 2012; 159:368-75. [DOI: 10.1016/j.jconrel.2012.01.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 12/29/2011] [Accepted: 01/22/2012] [Indexed: 10/14/2022]
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Xiang JN, Chen DL, Yang LY. Effect of PANDER in βTC6-cell lipoapoptosis and the protective role of exendin-4. Biochem Biophys Res Commun 2012; 421:701-6. [PMID: 22542939 DOI: 10.1016/j.bbrc.2012.04.065] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 04/13/2012] [Indexed: 12/29/2022]
Abstract
Chronic exposure to high concentrations of saturated fatty acids, such as palmitic acid (PA), leads to apoptosis of pancreatic β-cells through the activation of the c-Jun N-terminal kinase (JNK) signaling pathway. This study of β-cell lipoapoptosis was designed to investigate the roles of pancreatic-derived factor (PANDER), a pro-apoptosis cytokine-like peptide, and exendin-4, a long-acting agonist of the hormone glucagon-like peptide-1 (GLP-1) receptor and anti-apoptosis factor. The glucose-sensitive mouse β-pancreatic cell line, βTC6, was used to investigate the mechanisms of PA-induced apoptosis. Twenty-four hours of PA exposure led to increased PANDER expression in a dose- and time-dependent manner, and significantly increased phosphorylation of JNK. Treatment with the JNK-specific inhibitor SP600125 reduced the PA-induced PANDER expression. After the 24h of PA exposure, cells also underwent marked apoptosis and showed increased activation of the apoptosis protease, caspase-3. The small interfering (si)RNA-mediated silencing of PANDER gene expression significantly reduced both of these effects. When PA-treated βTC6 cells were exposed to exogenous exendin-4, JNK activation was inhibited, PANDER expression was decreased, and the numbers of apoptotic cells were reduced. Collectively, these results demonstrated that the JNK-mediated signaling mechanism of PA-induced β-cell apoptosis involves up-regulated expression of PANDER and activation of caspase-3. Exendin-4 may protect against lipoapoptosis by interfering with the JNK-PANDER pathway.
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Affiliation(s)
- Jing-Nan Xiang
- Department of Endocrinology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, Fujian 350005, China
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44
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Guan N, Gao W, He M, Zheng M, Xu X, Wang X, Wang MW. Dynamic monitoring of β-cell injury with impedance and rescue by glucagon-like peptide-1. Anal Biochem 2012; 423:61-9. [DOI: 10.1016/j.ab.2012.01.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 01/15/2012] [Accepted: 01/17/2012] [Indexed: 01/04/2023]
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45
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The development of Byetta (exenatide) from the venom of the Gila monster as an anti-diabetic agent. Toxicon 2012; 59:464-71. [DOI: 10.1016/j.toxicon.2010.12.016] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Accepted: 12/21/2010] [Indexed: 12/19/2022]
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46
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Suen CS, Burn P. The potential of incretin-based therapies in type 1 diabetes. Drug Discov Today 2011; 17:89-95. [PMID: 21920456 DOI: 10.1016/j.drudis.2011.08.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 08/25/2011] [Accepted: 08/30/2011] [Indexed: 02/07/2023]
Abstract
Finding a cure for type 1 diabetes (T1D) has been elusive. Incretin-based therapies, since their approval, have demonstrated their clinical utilities in type 2 diabetes (T2D). Yet, their potential clinical benefits in T1D remain to be appraised. GLP-1, in addition to its insulinotropic action in alleviating hyperglycemia, possesses beneficial effects in protecting progressive impairment of pancreatic β-cell function, preservation of β-cell mass and suppression of glucagon secretion, gastric emptying and appetite. Preclinical data using incretin-based therapies in diabetic NOD mice demonstrated additional effects including immuno-modulation, anti-inflammation and β-cell regeneration. Thus, data accumulated hold the promise that incretin-based therapies may be effective in delaying the new-onset, halting the further progression, or reversing T1D in subjects with newly diagnosed or long-standing, established disease.
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Affiliation(s)
- Chen S Suen
- The Sanford Project, Sanford Research, Sanford Health and Department of Pediatrics, Sanford School of Medicine of The University of South Dakota, 2301 East 60th Street North, Sioux Falls, SD 57104, USA
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Størling J, Juntti-Berggren L, Olivecrona G, Prause MC, Berggren PO, Mandrup-Poulsen T. Apolipoprotein CIII reduces proinflammatory cytokine-induced apoptosis in rat pancreatic islets via the Akt prosurvival pathway. Endocrinology 2011; 152:3040-8. [PMID: 21693679 DOI: 10.1210/en.2010-1422] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Apolipoprotein CIII (ApoCIII) is mainly synthesized in the liver and is important for triglyceride metabolism. The plasma concentration of ApoCIII is elevated in patients with type 1 diabetes (T1D), and in vitro ApoCIII causes apoptosis in pancreatic β-cells in the absence of inflammatory stress. Here, we investigated the effects of ApoCIII on function, signaling, and viability in intact rat pancreatic islets exposed to proinflammatory cytokines to model the intraislet inflammatory milieu in T1D. In contrast to earlier observations in mouse β-cells, exposure of rat islets to ApoCIII alone (50 μg/ml) did not cause apoptosis. In the presence of the islet-cytotoxic cytokines IL-1β + interferon-γ, ApoCIII reduced cytokine-mediated islet cell death and impairment of β-cell function. ApoCIII had no effects on mitogen-activated protein kinases (c-Jun N-terminal kinase, p38, and ERK) and had no impact on IL-1β-induced c-Jun N-terminal kinase activation. However, ApoCIII augmented cytokine-mediated nitric oxide (NO) production and inducible NO synthase expression. Further, ApoCIII caused degradation of the nuclear factor κB-inhibitor inhibitor of κB and stimulated Ser473-phosphorylation of the survival serine-threonine kinase Akt. Inhibition of the Akt signaling pathway by the phosphatidylinositol 3 kinase inhibitor LY294002 counteracted the antiapoptotic effect of ApoCIII on cytokine-induced apoptosis. We conclude that ApoCIII in the presence of T1D-relevant proinflammatory cytokines reduces rat pancreatic islet cell apoptosis via Akt.
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Affiliation(s)
- Joachim Størling
- Hagedorn Research Institute, Niels Steensens Vej 1, 2820 Gentofte, Denmark.
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Shirakawa J, Amo K, Ohminami H, Orime K, Togashi Y, Ito Y, Tajima K, Koganei M, Sasaki H, Takeda E, Terauchi Y. Protective effects of dipeptidyl peptidase-4 (DPP-4) inhibitor against increased β cell apoptosis induced by dietary sucrose and linoleic acid in mice with diabetes. J Biol Chem 2011; 286:25467-76. [PMID: 21613229 DOI: 10.1074/jbc.m110.217216] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Chronic exposure to high glucose and fatty acid levels caused by dietary sugar and fat intake induces β cell apoptosis, leading to the exacerbation of type 2 diabetes. Oleic acid and linoleic acid are two major dietary fatty acids, but their effects in diabetes are unclear. We challenged β cell-specific glucokinase haploinsufficient (Gck(+/-)) mice with a diet containing sucrose and oleic acid (SO) or sucrose and linoleic acid (SL) and analyzed β cell apoptosis. In Gck(+/-) but not wild-type mice, SL significantly decreased the β cell mass and β cell proportion in islet cells arising from increased apoptosis to a greater degree than did SO. The mRNA expression of SREBP-1c was significantly higher, and that of E-cadherin was significantly lower in the islets of Gck(+/-) mice fed SL compared with mice fed SO. We next evaluated monotherapy with desfluorositagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, in these mouse groups. DPP-4 inhibitor protected against β cell apoptosis, restored the β cell mass, and normalized islet morphology in Gck(+/-) mice fed SL. DPP-4 inhibition normalized the changes in the islet expression of SREBP-1c and E-cadherin mRNA induced by the SL diet. Furthermore, linoleic acid induced β cell apoptosis to a greater degree in the presence of high glucose levels than in the presence of low glucose levels in vitro in islets and MIN6 cells, whereas a GLP-1 receptor agonist prevented apoptosis. In conclusion, SL exacerbated β cell apoptosis in diabetic Gck(+/-) mice but not in euglycemic wild-type mice, and DPP-4 inhibition protected against these effects.
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Affiliation(s)
- Jun Shirakawa
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan
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Giorgino F, Leonardini A, Natalicchio A, Laviola L. Multifactorial intervention in Type 2 diabetes: the promise of incretin-based therapies. J Endocrinol Invest 2011; 34:69-77. [PMID: 21233599 DOI: 10.1007/bf03346698] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Type 2 diabetes mellitus is increasing in prevalence at alarming rates. Concurrent with its expanding prevalence is the increase in the related risk of morbidity and mortality. Because diabetic patients are prone to cardiovascular disease, treatment strategies should address the cardiovascular risk factors, including blood pressure, lipids, and body weight, in addition to the glycemic aspects of the disease. Newer agents, such as glucagon-like peptide-1 (GLP-1) analogs and dipeptidyl peptidase-4 (DPP-4) inhibitors, have varying degrees of evidence to support their effects on body weight, blood pressure, and lipid levels, beyond glycated hemoglobin reduction. While GLP-1 agonists produce a weight loss, the DPP-4 inhibitors, conversely, appear to have a weight-neutral effect. Substantial evidence demonstrates that both medications produce modest reductions in systolic blood pressure and, in some cases, diastolic blood pressure, and reduce several markers of cardiovascular risk, including C-reactive protein. Moreover, GLP-1 influences endothelial function. The effect of the incretin hormones on serum lipids are either neutral or beneficial, with small, non-significant decreases in LDL cholesterol, increases in HDL cholesterol, and occasionally significant decreases in fasting triglyceride levels. Also, they have positive effects on hepatic steatosis. Although GLP-1 agonists and DPP-4 inhibitors are at present not appropriate for primary treatment of cardiovascular risks factors, the reduction of these parameters is evidently beneficial.
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Affiliation(s)
- F Giorgino
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, I- 70124 Bari, Italy.
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Rohatgi N, Remedi MS, Kwon G, Pappan KL, Marshall CA, McDaniel ML. Therapeutic Strategies to Increase Human β-Cell Growth and Proliferation by Regulating mTOR and GSK-3/β-Catenin Pathways. ACTA ACUST UNITED AC 2010; 4. [PMID: 24339841 DOI: 10.2174/1874216501004010040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This perspective delineates approaches to develop therapeutic strategies to stimulate the proliferative potential of adult human β-cells in vitro. Previous findings demonstrated that nutrients, through regulation of mTOR signaling, promote regenerative processes including DNA synthesis, cell cycle progression and β-cell proliferation in rodent islets but rarely in human islets. Recently, we discovered that regulation of the Wnt/GSK-3/β-catenin pathway by directly inhibiting GSK-3 with pharmacologic agents, in combination with nutrient activation of mTOR, was required to increase growth and proliferation in human islets. Studies also revealed that nuclear translocation of β-catenin in response to GSK-3 inhibition regulated these processes and was rapamycin sensitive, indicating a role for mTOR. Human islets displayed a high level of insulin resistance consistent with the inability of exogenous insulin to activate Akt and engage the Wnt pathway by GSK-3 inhibition. This insulin resistance in human islets is not present in rodent islets and may explain the differential requirement in human islets to inhibit GSK-3 to enhance these regenerative processes. Human islets exhibited normal insulin secretion but a loss of insulin content, which was independent of all treatment conditions. The loss of insulin content may be related to insulin resistance, the isolation process or culture conditions. In this perspective, we provide strategies to enhance the proliferative capacity of adult human β-cells and highlight important differences between human and rodent islets: the lack of a nutrient response, requirement for direct GSK-3 inhibition, insulin resistance and loss of insulin content that emphasize the physiological significance of conducting studies in human islets.
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Affiliation(s)
- Nidhi Rohatgi
- Department of Pathology and Immunology, Washington University in St. Louis, St. Louis, Missouri, USA
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