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Moon JH, Choe HJ, Lim S. Pancreatic beta-cell mass and function and therapeutic implications of using antidiabetic medications in type 2 diabetes. J Diabetes Investig 2024; 15:669-683. [PMID: 38676410 PMCID: PMC11143426 DOI: 10.1111/jdi.14221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 03/23/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
Nowadays, the focus of diabetes treatment has switched from lowering the glucose level to preserving glycemic homeostasis and slowing the disease progression. The main pathophysiology of both type 1 diabetes and long-standing type 2 diabetes is pancreatic β-cell mass loss and dysfunction. According to recent research, human pancreatic β-cells possess the ability to proliferate in response to elevated insulin demands. It has been demonstrated that in insulin-resistant conditions in humans, such as obesity or pregnancy, the β-cell mass increases. This ability could be helpful in developing novel treatment approaches to restore a functional β-cell mass. Treatment strategies aimed at boosting β-cell function and mass may be a useful tool for managing diabetes mellitus and stopping its progression. This review outlines the processes of β-cell failure and detail the many β-cell abnormalities that manifest in people with diabetes mellitus. We also go over standard techniques for determining the mass and function of β-cells. Lastly, we provide the therapeutic implications of utilizing antidiabetic drugs in controlling the mass and function of pancreatic β-cells.
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Affiliation(s)
- Joon Ho Moon
- Department of Internal MedicineSeoul National University College of MedicineSeongnamSouth Korea
- Department of Internal MedicineSeoul National University Bundang HospitalSeongnamSouth Korea
| | - Hun Jee Choe
- Department of Internal MedicineHallym University Dongtan Sacred Heart HospitalHwaseongSouth Korea
| | - Soo Lim
- Department of Internal MedicineSeoul National University College of MedicineSeongnamSouth Korea
- Department of Internal MedicineSeoul National University Bundang HospitalSeongnamSouth Korea
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Lee D, Baek JY, Choi YJ, Han MJ, Kim SH, Kim TH, Lee S, Kang KS. Glucose-lowering effect of Reducose® enriched with 1-deoxynojirimycin and l-leucine: Studies on insulin secretion in INS-1 cells and reduction of blood glucose in diabetic rats. Heliyon 2024; 10:e25499. [PMID: 38333854 PMCID: PMC10850582 DOI: 10.1016/j.heliyon.2024.e25499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 02/10/2024] Open
Abstract
The extract of mulberry leaf and its active ingredients have already been reported to have anti-diabetic effects; however, further studies are required to obtain better quality extracts and higher yields of active ingredients. Reducose® is a commercially available aqueous extract of mulberry leaves with a high content of active ingredients. In this study, the biological activities of Reducose®, 1-deoxynojirimycin, and l-leucine were evaluated using a glucose-stimulated insulin secretion (GSIS) assay. The GSIS assay results were expressed as the glucose-stimulated index (GSI). Considering the pharmacological safety in pancreatic β-cells, the appropriate non-toxic concentrations were selected by screening for cytotoxicity of Reducose®, 1-deoxynojirimycin, and l-leucine before the GSIS assay. The effect of Reducose®, 1-deoxynojirimycin, and l-leucine on glucose-stimulated insulin secretion in INS-1 cells was compared. Reducose®, 1-deoxynojirimycin, and l-leucine increased the GSI values more effectively than gliclazide (positive control). This was associated with an increase in protein expression, such as peroxisome proliferator-activated receptor-γ, insulin receptor substrate-2, activated pancreatic and duodenal homeobox-1, which are related to the regulation of pancreatic β-cell function and survival. In order to elucidate the effect of Reducose® in anti-diabetic effects, blood glucose levels, insulin levels, and liver and lipid concentrations were investigated in a Sprague-Dawley rat model of high-fat diet/streptozotocin-induced diabetes. We observed that administration of Reducose® can decrease fasting blood glucose levels and reduce the production of AST, ALT, TG, and TC to a similar extent as metformin (positive control). These results suggested that Reducose® play a role in promoting GSIS but not enough to show that the content and proportion of 1-deoxynojirimycin and l-leucine play an important role in the GSIS activity of Reducose®.
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Affiliation(s)
- Dahae Lee
- College of Korean Medicine, Gachon University, Seongnam, 13120, Republic of Korea
| | - Ji Yun Baek
- College of Korean Medicine, Gachon University, Seongnam, 13120, Republic of Korea
| | - Ye Jung Choi
- College of Korean Medicine, Gachon University, Seongnam, 13120, Republic of Korea
| | - Min Ji Han
- Vixxol Corporation, Gunpo, 15807, Republic of Korea
| | - Seon Hwa Kim
- Vixxol Corporation, Gunpo, 15807, Republic of Korea
| | - Tae Hoon Kim
- Vixxol Corporation, Gunpo, 15807, Republic of Korea
| | - Sanghyun Lee
- Department of Plant Science and Technology, Chung-Ang University, Anseong, 17546, Republic of Korea
| | - Ki Sung Kang
- College of Korean Medicine, Gachon University, Seongnam, 13120, Republic of Korea
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3
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Riaz F, Wei P, Pan F. PPARs at the crossroads of T cell differentiation and type 1 diabetes. Front Immunol 2023; 14:1292238. [PMID: 37928539 PMCID: PMC10623333 DOI: 10.3389/fimmu.2023.1292238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/11/2023] [Indexed: 11/07/2023] Open
Abstract
T-cell-mediated autoimmune type 1 diabetes (T1D) is characterized by the immune-mediated destruction of pancreatic beta cells (β-cells). The increasing prevalence of T1D poses significant challenges to the healthcare system, particularly in countries with struggling economies. This review paper highlights the multifaceted roles of Peroxisome Proliferator-Activated Receptors (PPARs) in the context of T1D, shedding light on their potential as regulators of immune responses and β-cell biology. Recent research has elucidated the intricate interplay between CD4+ T cell subsets, such as Tregs and Th17, in developing autoimmune diseases like T1D. Th17 cells drive inflammation, while Tregs exert immunosuppressive functions, highlighting the delicate balance crucial for immune homeostasis. Immunotherapy has shown promise in reinstating self-tolerance and restricting the destruction of autoimmune responses, but further investigations are required to refine these therapeutic strategies. Intriguingly, PPARs, initially recognized for their role in lipid metabolism, have emerged as potent modulators of inflammation in autoimmune diseases, particularly in T1D. Although evidence suggests that PPARs affect the β-cell function, their influence on T-cell responses and their potential impact on T1D remains largely unexplored. It was noted that PPARα is involved in restricting the transcription of IL17A and enhancing the expression of Foxp3 by minimizing its proteasomal degradation. Thus, antagonizing PPARs may exert beneficial effects in regulating the differentiation of CD4+ T cells and preventing T1D. Therefore, this review advocates for comprehensive investigations to delineate the precise roles of PPARs in T1D pathogenesis, offering innovative therapeutic avenues that target both the immune system and pancreatic function. This review paper seeks to bridge the knowledge gap between PPARs, immune responses, and T1D, providing insights that may revolutionize the treatment landscape for this autoimmune disorder. Moreover, further studies involving PPAR agonists in non-obese diabetic (NOD) mice hold promise for developing novel T1D therapies.
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Affiliation(s)
- Farooq Riaz
- Shenzhen Institute of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Ping Wei
- Department of Otolaryngology, Ministry of Education Key Laboratory of Child Development and Disorders, National Clinical Research Center for Child Health and Disorders (Chongqing), China International Science and Technology Cooperation base of Child Development and Critical Disorders, Children’s Hospital of Chongqing Medical University, Chongqing, China
| | - Fan Pan
- Shenzhen Institute of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
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Yu F, Teng Y, Li J, Yang S, Zhang Z, He Y, Yang H, Ding CF, Zhou P. Effects of a Ganoderma lucidum Proteoglycan on Type 2 Diabetic Rats and the Recovery of Rat Pancreatic Islets. ACS OMEGA 2023; 8:17304-17316. [PMID: 37214729 PMCID: PMC10193549 DOI: 10.1021/acsomega.3c02200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 04/27/2023] [Indexed: 05/24/2023]
Abstract
Type 2 diabetes (T2D) results from both insulin resistance and pancreatic β-cell dysfunction. A natural proteoglycan extracted from Ganoderma lucidum, namely, FYGL, has been demonstrated to be capable of ameliorating insulin resistance in previous work. In this work, a T2D rat model induced by streptozocin (STZ) and a high-fat diet was used to investigate the effects of FYGL on pancreatic functions, and the transcriptomics of the rat pancreas was used to investigate the biological processes (BP) and signal pathways influenced by FYGL on the gene basis. Furthermore, the results of transcriptomics were verified both by histopathological analyses and protein expression. The studies showed that FYGL positively regulated T2D-related BP and signaling pathways and recovered the pancreatic function, therefore ameliorating hyperglycemia and hyperlipidemia in vivo. Importantly, the recovery of the pancreatic function suggested a crucial strategy to radically treat T2D.
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Affiliation(s)
- Fanzhen Yu
- State
Key Laboratory of Molecular Engineering of Polymers, Department of
Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Yilong Teng
- State
Key Laboratory of Molecular Engineering of Polymers, Department of
Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Jiaqi Li
- State
Key Laboratory of Molecular Engineering of Polymers, Department of
Macromolecular Science, Fudan University, Shanghai 200433, China
| | - Shutong Yang
- Department
of Chemistry, Fudan University, Shanghai 200433, China
| | - Zeng Zhang
- Yueyang
Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, P. R. China
| | - Yanming He
- Yueyang
Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, P. R. China
| | - Hongjie Yang
- Yueyang
Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, P. R. China
| | - Chuan-Fan Ding
- Zhejiang
Provincial Key Laboratory of Advanced Mass Spectrometry and Molecular
Analysis, Institute of Mass Spectrometry, School of Material Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Ping Zhou
- State
Key Laboratory of Molecular Engineering of Polymers, Department of
Macromolecular Science, Fudan University, Shanghai 200433, China
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Hwang H, Lee D, Son JD, Baek JG, Lee HS, Park I, Kim DH, Lee SK, Kim WK, Kwon HC, Kang KS, Kwon J. Chemical constituents isolated from Actinidia polygama and their α-glucosidase inhibitory activity and insulin secretion effect. Bioorg Chem 2023; 134:106466. [PMID: 36934691 DOI: 10.1016/j.bioorg.2023.106466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/14/2023]
Abstract
Actinidia polygama has been used as a traditional medicine for treating various diseases. In the present study, 13 compounds, including three new monoterpenoids (1-3), were isolated from the leaves of A. polygama to investigate the bioactive constituents of the plant. The structures were characterized by analyzing spectroscopic and chiroptical data. These compounds were preliminarily screened for their ability to increase insulin secretion levels after glucose stimulation. Of these, 3-O-coumaroylmaslinic acid (4) and jacoumaric acid (5) showed activity. In further biological studies, these compounds exhibited increased glucose-stimulated insulin secretion (GSIS) activity without cytotoxicity in rat INS-1 pancreatic β-cells as well as α-glucosidase inhibitory activity. Furthermore, both compounds increased insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), pancreatic and duodenal homeobox-1 (PDX-1), and peroxisome proliferator-activated receptor-γ (PPAR-γ) expression. Hence, these compounds may be developed as potential antidiabetic agents.
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Affiliation(s)
- Hoseong Hwang
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Dahae Lee
- College of Korean Medicine, Gachon University, Seongnam 13120, Republic of Korea
| | - Jong Dai Son
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Jong Gwon Baek
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Hyeon-Seong Lee
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - InWha Park
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Dong Hoon Kim
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Soon Kwang Lee
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Won Kyu Kim
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Hak Cheol Kwon
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea
| | - Ki Sung Kang
- College of Korean Medicine, Gachon University, Seongnam 13120, Republic of Korea.
| | - Jaeyoung Kwon
- KIST Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangneung 25451, Republic of Korea; Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Gangneung 25451, Republic of Korea.
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6
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Lee D, Son SR, Qi Y, Kang KS, Jang DS. (1' S)-1'-Acetoxyeugenol Acetate Enhances Glucose-Stimulated Insulin Secretion. PLANTS (BASEL, SWITZERLAND) 2023; 12:579. [PMID: 36771665 PMCID: PMC9919771 DOI: 10.3390/plants12030579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/25/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
Alpinia galanga have been widely used as spice or traditional medicine in East Asia, commonly known as Thai ginger. In the present study, seven major phenylpropanoids, (±)-1'-hydoxychavicol acetate (1; HCA), (1'S)-1'-acetoxychavicol acetate (2; ACA), (1'S)-1'-acetoxyeugenol acetate (3; AEA), eugenyl acetate (4), trans-p-coumaraldehyde (5), trans-p-acetoxycinnamyl alcohol (6), and trans-p-coumaryl diacetate (7), were isolated from the 95% EtOH and hot water extracts of the rhizomes of A. galanga by chromatographic method. Phenylpropanoids 1-7 were evaluated for glucose-stimulated insulin secretion (GSIS) effect and α-glucosidase inhibitory activity. Phenylpropanoids 1-4 increase GSIS effect without cytotoxicity in rat INS-1 pancreatic β-cells. In addition, INS-1 cells were treated with AEA (3) to determine a plausible mechanism of β-cell function and insulin secretion through determining the activation of insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), Akt, and pancreatic and duodenal homeobox-1 (PDX-1). Upon treatment with AEA (3), INS-1 cells showed an increase in these protein expressions. Meanwhile, AEA (3) exhibited α-glucosidase inhibitory activity. On the basis of the above findings, we suggest AEA (3) as a potential antidiabetic agent.
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Affiliation(s)
- Dahae Lee
- College of Korean Medicine, Gachon University, Seongnam 13120, Republic of Korea
| | - So-Ri Son
- Department of Biomedical and Pharmaceutical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Yutong Qi
- Department of Life and Nanopharmaceutical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Ki Sung Kang
- College of Korean Medicine, Gachon University, Seongnam 13120, Republic of Korea
| | - Dae Sik Jang
- Department of Biomedical and Pharmaceutical Sciences, Graduate School, Kyung Hee University, Seoul 02447, Republic of Korea
- Department of Pharmaceutical Science, College of Pharmacy, Kyung Hee University, Seoul 02447, Republic of Korea
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The Role of Transcription Factor PPAR-γ in the Pathogenesis of Psoriasis, Skin Cells, and Immune Cells. Int J Mol Sci 2022; 23:ijms23179708. [PMID: 36077103 PMCID: PMC9456565 DOI: 10.3390/ijms23179708] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 11/22/2022] Open
Abstract
The peroxisome proliferator-activated receptor PPAR-γ is one of three PPAR nuclear receptors that act as ligand-activated transcription factors. In immune cells, the skin, and other organs, PPAR-γ regulates lipid, glucose, and amino acid metabolism. The receptor translates nutritional, pharmacological, and metabolic stimuli into the changes in gene expression. The activation of PPAR-γ promotes cell differentiation, reduces the proliferation rate, and modulates the immune response. In the skin, PPARs also contribute to the functioning of the skin barrier. Since we know that the route from identification to the registration of drugs is long and expensive, PPAR-γ agonists already approved for other diseases may also represent a high interest for psoriasis. In this review, we discuss the role of PPAR-γ in the activation, differentiation, and proliferation of skin and immune cells affected by psoriasis and in contributing to the pathogenesis of the disease. We also evaluate whether the agonists of PPAR-γ may become one of the therapeutic options to suppress the inflammatory response in lesional psoriatic skin and decrease the influence of comorbidities associated with psoriasis.
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Jetton TL, Flores-Bringas P, Leahy JL, Gupta D. SetD7 (Set7/9) is a novel target of PPARγ that promotes the adaptive pancreatic β-cell glycemic response. J Biol Chem 2021; 297:101250. [PMID: 34592314 PMCID: PMC8526774 DOI: 10.1016/j.jbc.2021.101250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 09/20/2021] [Accepted: 09/24/2021] [Indexed: 11/25/2022] Open
Abstract
Loss of functional pancreatic β-cell mass leads to type 2 diabetes (T2D), attributable to modified β-cell-dependent adaptive gene expression patterns. SetD7 is a histone methyltransferase enriched in pancreatic islets that mono- and dimethylates histone-3-lysine-4 (H3K4), promoting euchromatin modifications, and also maintains the regulation of key β-cell function and survival genes. However, the transcriptional regulation of this important epigenetic modifier is unresolved. Here we identified the nuclear hormone receptor peroxisome proliferator-activated receptor-gamma (PPARγ) as a major transcriptional regulator of SetD7 and provide evidence for direct binding and functionality of PPARγ in the SetD7 promoter region. Furthermore, constitutive shRNA-mediated PPARγ knockdown in INS-1 β-cells or pancreas-specific PPARγ deletion in mice led to downregulation of SetD7 expression as well as its nuclear enrichment. The relevance of the SetD7-PPARγ interaction in β-cell adaptation was tested in normoglycemic 60% partial pancreatectomy (Px) and hyperglycemic 90% Px rat models. Whereas a synergistic increase in islet PPARγ and SetD7 expression was observed upon glycemic adaptation post-60% Px, in hyperglycemic 90% Px rats, islet PPARγ, and PPARγ targets SetD7 and Pdx1 were downregulated. PPARγ agonist pioglitazone treatment in 90% Px rats partially restored glucose homeostasis and β-cell mass and enhanced expression of SetD7 and Pdx1. Collectively, these data provide evidence that the SetD7-PPARγ interaction serves as an important element of the adaptive β-cell response.
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Affiliation(s)
- Thomas L Jetton
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Patricio Flores-Bringas
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - John L Leahy
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Dhananjay Gupta
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA.
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The Chemical Constituents from Fruits of Catalpa bignonioides Walt. and Their α-Glucosidase Inhibitory Activity and Insulin Secretion Effect. Molecules 2021; 26:molecules26020362. [PMID: 33445612 PMCID: PMC7826643 DOI: 10.3390/molecules26020362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 11/24/2022] Open
Abstract
Catalpa pod has been used in traditional medicine for the treatment of diabetes mellitus in South America. Studies on the constituents of Catalpa species have shown that it is rich in iridoids. In the present study, three previously undescribed compounds (2–4), including two secoiridoid derivatives along with twelve known compounds, were isolated from the fruits of Catalpa bignonioides Walt. In addition, fully assigned 13C-NMR of 5,6-dihydroxy-7,4’-dimethoxyflavone-6-O-sophoroside (1) is reported for the first time in the present study. The structures of compounds were determined on the basis of extensive spectroscopic methods, including UV, IR, 1D, and 2D NMR, mass spectroscopy, and CD spectroscopic data. All the isolated compounds were evaluated for α-glucosidase inhibitory activity. Among the tested compounds, compounds 2, 3, and 9 exhibited significant inhibitory activity against α-glucosidase enzyme assay. Meanwhile, the effect of compounds 2, 3, and 9 on glucose-stimulated insulin secretion (GSIS) was measured using pancreatic β-cells. Compounds 2, 3, and 9 exhibited non-cytotoxicity-stimulated insulin secretion in INS-1 cells. The expression levels of proteins associated with β-cell function and insulin secretion such as phosphorylation of total insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), Akt, activated pancreatic duodenal homeobox-1 (PDX-1), and peroxisome proliferator-activated receptor-γ (PPAR-γ) were increased in INS-1 cells after treatment with compounds 2, 3, and 9. The findings of the present study could provide a scientific warrant for their application as a potential antidiabetic agent.
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Comparisons between dipeptidyl peptidase-4 inhibitors and other classes of hypoglycemic drugs using two distinct biomarkers of pancreatic beta-cell function: A meta-analysis. PLoS One 2020; 15:e0236603. [PMID: 32706828 PMCID: PMC7380634 DOI: 10.1371/journal.pone.0236603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/08/2020] [Indexed: 01/09/2023] Open
Abstract
Background and objective Dipeptidyl peptidase-4 (DPP-4) inhibitors have been suggested to have pancreatic beta-cell preserving effect according to studies using homeostatic model of assessment for beta-cell function (HOMA-β). However, whether HOMA-β is a suitable biomarker for comparisons between hypoglycemic drugs with different mechanisms of action remains unclear. Therefore, we conducted a meta-analysis to compare the effects of DPP-4 inhibitors and other classes of hypoglycemic drugs on HOMA-β and proinsulin-to-insulin ratio (PIR). Methods We searched MEDLINE, CENTRAL, and Ichushi-web for the period of 1966 to May 2020. We collected randomized, controlled clinical trials in patients with type 2 diabetes mellitus comparing DPP-4 inhibitors and other classes of hypoglycemic agents [α-glucosidase inhibitors (α-GIs), glucagon-like peptide-1 (GLP-1) analogues, metformin, sodium-glucose cotransporter 2 (SGLT2) inhibitors, sulfonylureas, or thiazolidinediones]. Weighted mean differences and 95% confidence intervals of changes in HOMA-β or PIR during study periods were calculated for pairwise comparisons. Results Thirty-seven and 21 relevant trials were retrieved for comparisons of HOMA-β and PIR, respectively. HOMA-β and PIR consistently showed superiority of DPP-4 inhibitors compared with α-GIs. Both biomarkers consistently supported inferiority of DPP-4 inhibitors compared with GLP-1 analogues. However, PIR showed inferiority of DPP-4 inhibitors compared with metformin, and superiority compared with SGLT2 inhibitors, whereas HOMA-β showed no significant differences between DPP-4 inhibitors and the two other agents. Conclusion DPP-4 inhibitors appear to be superior to α-GIs but inferior to GLP-1 analogues in preservation of beta-cell function assessed by either HOMA-β or PIR. DPP-4 inhibitors seem to be superior to SGLT2 inhibitors but inferior to metformin on islet function assessed only by PIR. Because HOMA-β and PIR may indicate different aspects of beta-cell function, results of beta-cell function preserving effects of hypoglycemic agents should be interpreted with caution.
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11
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Xiong J, Sun P, Wang Y, Hua X, Song W, Wang Y, Wu J, Yu W, Liu G, Chen L. Heterozygous deletion of Seipin in islet beta cells of male mice has an impact on insulin synthesis and secretion through reduced PPARγ expression. Diabetologia 2020; 63:338-350. [PMID: 31776610 DOI: 10.1007/s00125-019-05038-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 10/03/2019] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is an autosomal recessive disorder characterised by lipodystrophy and insulin resistance. BSCL2 is caused by loss-of-function mutations in the Seipin gene (also known as Bscl2). Deletion of this gene in mice induces insulin resistance, glucose intolerance and a loss of adipose tissue. This study evaluated the effects of genetic deletion of Seipin on islet beta cell function. METHODS We examined seipin expression in islet cells and measured glucose profiles, insulin synthesis, glucose-stimulated insulin secretion (GSIS), islet expression of peroxisome proliferator-activated receptor γ (PPARγ), levels of Pdx-1, Nkx6.1, Glut2 (also known as Slc2a2) and proinsulin mRNA, nuclear translocation of pancreatic duodenal homeobox 1 (PDX-1), islet numbers, and beta cell mass and proliferation in male and female Seipin-knockout homozygous (Seipin-/-) and heterozygous (Seipin+/-) mice. RESULTS Male and female Seipin-/- mice displayed glucose intolerance, insulin resistance, hyperinsulinaemia and a lack of adipose tissue. By contrast, male but not female Seipin+/- mice showed glucose intolerance without adipose tissue loss or insulin resistance. Seipin was highly expressed in islet beta cells in wild-type mice. Expression of islet PPARγ was reduced in male Seipin-/- and Seipin+/- mice but not in female Seipin-/- or Seipin+/- mice. Treatment of male Seipin+/- mice with rosiglitazone corrected the glucose intolerance. Male Seipin+/- mice displayed a decrease in islet insulin concentration and GSIS with low expression of Pdx-1, Nkx6.1, Glut2 and proinsulin, and a decline in PDX-1 nuclear translocation; these changes were rescued by rosiglitazone administration. Male Seipin-/- mice showed obvious, but rosiglitazone-sensitive, increases in islet insulin concentration, islet number and beta cell mass and proliferation, with a notable decline in GSIS. Ovariectomised female Seipin+/- mice displayed glucose intolerance and deficits in insulin synthesis and secretion, with a decline in islet PPARγ level; these deleterious effects were reversed by administration of oestradiol or rosiglitazone. CONCLUSIONS/INTERPRETATION Heterozygous deletion of Seipin in islet beta cells impacts on insulin synthesis and secretion through reduced PPARγ expression. This leads to glucose intolerance and is relieved by oestradiol, which rescues PPARγ expression.
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Affiliation(s)
- Jianwei Xiong
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Peng Sun
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China
| | - Ya Wang
- Department of Physiology, Nanjing Medical University, Longmian Road 101, Nanjing, 211166, China
| | - Xu Hua
- Department of Physiology, Nanjing Medical University, Longmian Road 101, Nanjing, 211166, China
| | - Wenyu Song
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China
| | - Yan Wang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, China
| | - Jie Wu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Wenfeng Yu
- Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang, 550004, China.
| | - George Liu
- Institute of Cardiovascular Sciences, Peking University and Key Laboratory of Cardiovascular Sciences, China Administration of Education, Beijing, 100191, China.
| | - Ling Chen
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China.
- Department of Physiology, Nanjing Medical University, Longmian Road 101, Nanjing, 211166, China.
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12
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Abstract
Peroxisome proliferator-activated receptors (PPARs) are a family of transcription factors with a key role in glucose and lipid metabolism. PPARs are expressed in many cell types including pancreatic beta cells and immune cells, where they regulate insulin secretion and T cell differentiation, respectively. Moreover, various PPAR agonists prevent diabetes in the non-obese diabetic (NOD) mouse model of type 1 diabetes. PPARs are thus of interest in type 1 diabetes (T1D) as they represent a novel approach targeting both the pancreas and the immune system. In this review, we examine the role of PPARs in immune responses and beta cell biology and their potential as targets for treatment of T1D.
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13
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Abdel-Rahman MA, Mohammed AK, Ahmed SH, Binnaser YS, Abdel-Nabi IM. Antidiabetic effect of the scorpion Scorpio maurus palmatusbody extract using alloxan-induced diabetic mice model. JOURNAL OF TAIBAH UNIVERSITY FOR SCIENCE 2019. [DOI: 10.1080/16583655.2019.1599184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Mohamed A. Abdel-Rahman
- Zoology Department, Faculty of Science, Molecular Physiology & Toxinology, Suez Canal University, Ismailia, Egypt
- Institute of Biotechnology for Graduate Studies and Research, Suez Canal University, Ismailia, Egypt
| | - Ahmad K. Mohammed
- Department of Biotechnology, Faculty of Science, Port Said University, Port Said, Egypt
| | - Sherifa H. Ahmed
- Department of Biotechnology, Faculty of Science, Port Said University, Port Said, Egypt
- Department of Biology, Faculty of Science, Jouf University, Skaka, KSA
| | - Yaser S. Binnaser
- Department of Biology, College of Science, Taibah University, Madinah, KSA
| | - Ismail M. Abdel-Nabi
- Zoology Department, Faculty of Science, Molecular Physiology & Toxinology, Suez Canal University, Ismailia, Egypt
- Department of Biology, College of Science, Taibah University, Madinah, KSA
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14
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Silva AR, Gonçalves-de-Albuquerque CF, Pérez AR, Carvalho VDF. Immune-endocrine interactions related to a high risk of infections in chronic metabolic diseases: The role of PPAR gamma. Eur J Pharmacol 2019; 854:272-281. [PMID: 30974105 DOI: 10.1016/j.ejphar.2019.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 03/11/2019] [Accepted: 04/02/2019] [Indexed: 02/06/2023]
Abstract
Diverse disturbances in immune-endocrine circuitries are involved in the development and aggravation of several chronic metabolic diseases (CMDs), including obesity, diabetes, and metabolic syndrome. The chronic inflammatory syndrome observed in CMDs culminates in dysregulated immune responses with low microbial killing efficiency, by means low host innate immune response, and loss of ability to eliminate the pathogens, which results in a high prevalence of infectious diseases, including pneumonia, tuberculosis, and sepsis. Herein, we review evidence pointing out PPARγ as a putative player in immune-endocrine disturbances related to increased risk of infections in CMDs. Cumulated evidence indicates that PPARγ activation modulates host cells to control inflammation during CMDs because of PPARγ agonists have anti-inflammatory and pro-resolutive properties, increasing host ability to eliminate pathogen, modulating hormone production, and restoring glucose and lipid homeostasis. As such, we propose PPARγ as a putative therapeutic adjuvant for patients with CMDs to favor a better infection control.
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Affiliation(s)
- Adriana Ribeiro Silva
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Avenida Brasil, 4365, Rio de Janeiro, RJ, Brazil.
| | - Cassiano Felippe Gonçalves-de-Albuquerque
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Avenida Brasil, 4365, Rio de Janeiro, RJ, Brazil; Laboratório de Imunofarmacologia, Instituto Biomédico, Universidade Federal do Estado do Rio de Janeiro, Unirio, Brazil.
| | - Ana Rosa Pérez
- Instituto de Inmunología Clínica y Experimental de Rosario (IDICER-CONICET UNR), 2000, Rosario, Argentina.
| | - Vinicius de Frias Carvalho
- Laboratório de Inflamação, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Avenida Brasil, 4365, Rio de Janeiro, RJ, Brazil.
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15
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PPAR𝛾 Gene and Atherosclerosis: Genetic Polymorphisms, Epigenetics and Therapeutic Implications. Balkan J Med Genet 2018; 21:39-46. [PMID: 30425909 PMCID: PMC6231320 DOI: 10.2478/bjmg-2018-0011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Atherosclerosis is the leading cause of mortality and morbidity in the developed world. It is characterized by the formation of a plaque in the walls of middle and large arteries leading to macrovascular complications. Several risk factors are included, with diabetes being one of the most important for the onset and development of atherosclerosis. Due to an increase in the prevalence of diabetes in the world, the incidence of diabetic complications (microvascular and macrovascular) is increasing. Peroxisome proliferator-activated receptor γ (PPARγ) plays a important role in atherosclerotic processes. Peroxisome proliferator activated receptor γ belongs to the superfamily of nuclear receptors, has a great presence in fat tissue, macrophages, and regulates gene expression and most of the processes that lead to the onset and development of atherosclerosis. In this review, we discuss the basic patho-physiological mechanisms of atherosclerosis in type 2 diabetes mellitus (T2DM). Furthermore, we discuss the impact of PPARγ polymorphisms, and the epigenetic mechanisms affecting the onset of atherosclerosis, i.e, DNA methylation and demethylation, histone acetylation and deacetylation, and RNA-based mechanisms. Moreover, we add therapeutic possibilities for acting on epigenetic mechanisms in order to prevent the onset and progression of atherosclerosis.
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16
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Xu M, Yang X, Zeng Q, He H, Lu P, Huang G. BIRC5 is a novel target of peroxisome proliferator‑activated receptor γ in brain microvascular endothelium cells during cerebral ischemia. Mol Med Rep 2017; 16:8882-8890. [PMID: 29039513 PMCID: PMC5779969 DOI: 10.3892/mmr.2017.7750] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 08/16/2017] [Indexed: 11/23/2022] Open
Abstract
Cerebral ischemia is a leading cause of ischemic stroke, which may lead to severe disability and mortality worldwide. There are some key factors concerned in cardioprotection, such as peroxisome proliferator-activated receptor γ (PPARγ), a ligand binding transcription factor involved in various biological functions including atherosclerosis, vascular dysfunction and hypertension, and baculoviral IAP repeat-containing 5 (BIRC5), which may protect human brain endothelial cells from ischemia-induced apoptosis. To determine the potential roles of PPARγ in brain microvascular endothelial (bEnd.3) cells during cerebral ischemia and the relationship between PPARγ and BIRC5, a cerebral ischemia model was established with bEnd.3 cells cells by oxygen-glucose deprivation (OGD) treatment. OGD treatment reduced proliferation and enhanced apoptosis of bEnd.3 cells in a time-dependent manner. PPARγ expression levels were decreased in bEnd.3 cells following OGD treatment. Upregulation of PPARγ expression protected bEnd.3 cells from ischemia injury and also upregulated BIRC5 expression. PPARγ-specific binding sites in the BIRC5 promoter were predicted bioinformatically and verified by luciferase reporter experiments. Results from electrophoretic mobility shift/supershift and chromatin immunoprecipitation assays suggested that BIRC5 may be a novel target of PPARγ transcriptional regulation during ischemic injury. The present results indicated that PPARγ may serve a protective role on bEnd.3 cells and that BIRC5 may be a downstream target of PPARγ regulation during cerebral ischemia.
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Affiliation(s)
- Mingjing Xu
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Xianli Yang
- Department of Medical Quality Management, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, P.R. China
| | - Qing Zeng
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - He He
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Pengcheng Lu
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
| | - Guozhi Huang
- Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, P.R. China
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17
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Gupta D, Jetton TL, LaRock K, Monga N, Satish B, Lausier J, Peshavaria M, Leahy JL. Temporal characterization of β cell-adaptive and -maladaptive mechanisms during chronic high-fat feeding in C57BL/6NTac mice. J Biol Chem 2017; 292:12449-12459. [PMID: 28487366 DOI: 10.1074/jbc.m117.781047] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/29/2017] [Indexed: 12/18/2022] Open
Abstract
The onset of type 2 diabetes is characterized by transition from successful to failed insulin secretory compensation to obesity-related insulin resistance and dysmetabolism. Energy-rich diets in rodents are commonly studied models of compensatory increases in both insulin secretion and β cell mass. However, the mechanisms of these adaptive responses are incompletely understood, and it is also unclear why these responses eventually fail. We measured the temporal trends of glucose homeostasis, insulin secretion, β cell morphometry, and islet gene expression in C57BL/6NTac mice fed a 60% high-fat diet (HFD) or control diet for up to 16 weeks. A 2-fold increased hyperinsulinemia was maintained for the first 4 weeks of HFD feeding and then further increased through 16 weeks. β cell mass increased progressively starting at 4 weeks, principally through nonproliferative growth. Insulin sensitivity was not significantly perturbed until 11 weeks of HFD feeding. Over the first 8 weeks, we observed two distinct waves of increased expression of β cell functional and prodifferentiation genes. This was followed by activation of the unfolded protein response at 8 weeks and overt β cell endoplasmic reticulum stress at 12-16 weeks. In summary, β cell adaptation to an HFD in C57BL/6NTac mice entails early insulin hypersecretion and a robust growth phase along with hyperexpression of related genes that begin well before the onset of observed insulin resistance. However, continued HFD exposure results in cessation of gene hyperexpression, β cell functional failure, and endoplasmic reticulum stress. These data point to a complex but not sustainable integration of β cell-adaptive responses to nutrient overabundance, obesity development, and insulin resistance.
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Affiliation(s)
- Dhananjay Gupta
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Thomas L Jetton
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Kyla LaRock
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Navjot Monga
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Basanthi Satish
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - James Lausier
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Mina Peshavaria
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446
| | - Jack L Leahy
- Division of Endocrinology, Diabetes, and Metabolism, University of Vermont, Burlington, Vermont 05446.
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18
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Yang Y, Gong L. Palmitoleate inhibits insulin transcription by activating the ERK1/2 pathway in rat pancreatic β-cells. Exp Ther Med 2017; 13:2805-2811. [PMID: 28587345 PMCID: PMC5450653 DOI: 10.3892/etm.2017.4344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/04/2016] [Indexed: 02/05/2023] Open
Abstract
The aim of the present study was to evaluate the effects of palmitoleate on insulin secretion and insulin mRNA levels, and to investigate the transcriptional regulation of insulin. INS-1 rat insulinoma cells were treated with palmitoleate in the presence of high glucose, and the amount of secreted insulin was measured via radioimmunoassay. Reverse transcription-quantitative polymerase chain reaction was performed to evaluate the mRNA levels of insulin and pancreatic and duodenal homeobox 1 (PDX1) under palmitoleate treatment. The levels of PDX1, peroxisome proliferator-activated receptor gamma (PPARG), extracellular signal-regulated kinase (ERK)1/2 and phosphorylated ERK1/2 were measured using western blot analysis. Low concentrations of palmitoleate significantly induced insulin secretion (P=0.024), whereas the mRNA levels of insulin and PDX1 were markedly reduced. However, the inhibitory effects were reversed with the addition of U0126, suggesting that the ERK1/2-mediated pathway may be the underlying mechanism responsible for palmitoleate-induced downregulation of insulin mRNA. Exposure of INS-1 cells to high glucose significantly increased the phosphorylation of ERK1/2 (P=0.039), which was further enhanced by palmitoleate (P=0.025). Exposure of INS-1 cells to high glucose significantly decreased PPARG (P=0.001), which was further decreased by the addition of palmitoleate. U0126 was able to reverse the palmitoleate-induced effects. In conclusion, the present study suggested that palmitoleate may induce insulin secretion and inhibit insulin mRNA expression in pancreatic β-cells.
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Affiliation(s)
- Yumei Yang
- Department of Endocrinology and Metabolism, The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, P.R. China
| | - Liangliang Gong
- Department of Rheumatology, The Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, P.R. China
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19
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Maganti AV, Tersey SA, Syed F, Nelson JB, Colvin SC, Maier B, Mirmira RG. Peroxisome Proliferator-activated Receptor-γ Activation Augments the β-Cell Unfolded Protein Response and Rescues Early Glycemic Deterioration and β Cell Death in Non-obese Diabetic Mice. J Biol Chem 2016; 291:22524-22533. [PMID: 27613867 DOI: 10.1074/jbc.m116.741694] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 09/05/2016] [Indexed: 12/11/2022] Open
Abstract
Type 1 diabetes is an autoimmune disorder that is characterized by a failure of the unfolded protein response in islet β cells with subsequent endoplasmic reticulum stress and cellular death. Thiazolidinediones are insulin sensitizers that activate the nuclear receptor PPAR-γ and have been shown to partially ameliorate autoimmune type 1 diabetes in humans and non-obese diabetic (NOD) mice. We hypothesized that thiazolidinediones reduce β cell stress and death independently of insulin sensitivity. To test this hypothesis, female NOD mice were administered pioglitazone during the pre-diabetic phase and assessed for insulin sensitivity and β cell function relative to controls. Pioglitazone-treated mice showed identical weight gain, body fat distribution, and insulin sensitivity compared with controls. However, treated mice showed significantly improved glucose tolerance with enhanced serum insulin levels, reduced β cell death, and increased β cell mass. The effect of pioglitazone was independent of actions on T cells, as pancreatic lymph node T cell populations were unaltered and T cell proliferation was unaffected by pioglitazone. Isolated islets of treated mice showed a more robust unfolded protein response, with increases in Bip and ATF4 and reductions in spliced Xbp1 mRNA. The effect of pioglitazone appears to be a direct action on β cells, as islets from mice treated with pioglitazone showed reductions in PPAR-γ (Ser-273) phosphorylation. Our results demonstrate that PPAR-γ activation directly improves β cell function and survival in NOD mice by enhancing the unfolded protein response and suggest that blockade of PPAR-γ (Ser-273) phosphorylation may prevent type 1 diabetes.
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Affiliation(s)
- Aarthi V Maganti
- From the Department of Cellular and Integrative Physiology.,Center for Diabetes and Metabolic Diseases
| | - Sarah A Tersey
- Center for Diabetes and Metabolic Diseases.,Department of Pediatrics and the Herman B Wells Center
| | - Farooq Syed
- Department of Pediatrics and the Herman B Wells Center
| | | | - Stephanie C Colvin
- Center for Diabetes and Metabolic Diseases.,Department of Pediatrics and the Herman B Wells Center
| | - Bernhard Maier
- Center for Diabetes and Metabolic Diseases.,Department of Pediatrics and the Herman B Wells Center
| | - Raghavendra G Mirmira
- From the Department of Cellular and Integrative Physiology, .,Center for Diabetes and Metabolic Diseases.,Department of Pediatrics and the Herman B Wells Center.,Department of Medicine, and.,Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202 and.,Indiana Biosciences Research Institute, Indianapolis, Indiana 46202
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20
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Is the Mouse a Good Model of Human PPARγ-Related Metabolic Diseases? Int J Mol Sci 2016; 17:ijms17081236. [PMID: 27483259 PMCID: PMC5000634 DOI: 10.3390/ijms17081236] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/19/2016] [Accepted: 07/21/2016] [Indexed: 12/21/2022] Open
Abstract
With the increasing number of patients affected with metabolic diseases such as type 2 diabetes, obesity, atherosclerosis and insulin resistance, academic researchers and pharmaceutical companies are eager to better understand metabolic syndrome and develop new drugs for its treatment. Many studies have focused on the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ), which plays a crucial role in adipogenesis and lipid metabolism. These studies have been able to connect this transcription factor to several human metabolic diseases. Due to obvious limitations concerning experimentation in humans, animal models—mainly mouse models—have been generated to investigate the role of PPARγ in different tissues. This review focuses on the metabolic features of human and mouse PPARγ-related diseases and the utility of the mouse as a model.
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21
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Güven C, Dal F, Aydoğan Ahbab M, Taskin E, Ahbab S, Adin Çinar S, Sırma Ekmekçi S, Güleç Ç, Abacı N, Akçakaya H. Low dose monoethyl phthalate (MEP) exposure triggers proliferation by activating PDX-1 at 1.1B4 human pancreatic beta cells. Food Chem Toxicol 2016; 93:41-50. [DOI: 10.1016/j.fct.2016.04.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 04/24/2016] [Accepted: 04/26/2016] [Indexed: 10/21/2022]
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22
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So WY, Leung PS. Fibroblast Growth Factor 21 As an Emerging Therapeutic Target for Type 2 Diabetes Mellitus. Med Res Rev 2016; 36:672-704. [PMID: 27031294 DOI: 10.1002/med.21390] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 12/13/2015] [Accepted: 02/15/2016] [Indexed: 12/19/2022]
Abstract
Fibroblast growth factor (FGF) 21 is a distinctive member of the FGF family that functions as an endocrine factor. It is expressed predominantly in the liver, but is also found in adipose tissue and the pancreas. Pharmacological studies have shown that FGF21 normalizes glucose and lipid homeostasis, thereby preventing the development of metabolic disorders, such as obesity and diabetes. Despite growing evidence for the therapeutic potential of FGF21, paradoxical increases of FGF21 in different disease conditions point to the existence of FGF21 resistance. In this review, we give a critical appraisal of recent advances in the understanding of the regulation of FGF21 production under various physiological conditions, its antidiabetic actions, and the clinical implications. We also discuss recent preclinical and clinical trials using engineered FGF21 analogs in the management of diabetes, as well as the potential side effects of FGF21 therapy.
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Affiliation(s)
- Wing Yan So
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Po Sing Leung
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, Hong Kong, China
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23
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Polvani S, Tarocchi M, Tempesti S, Bencini L, Galli A. Peroxisome proliferator activated receptors at the crossroad of obesity, diabetes, and pancreatic cancer. World J Gastroenterol 2016; 22:2441-2459. [PMID: 26937133 PMCID: PMC4768191 DOI: 10.3748/wjg.v22.i8.2441] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 12/17/2015] [Accepted: 01/11/2016] [Indexed: 02/06/2023] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is the fourth cause of cancer death with an overall survival of 5% at five years. The development of PDAC is characteristically associated to the accumulation of distinctive genetic mutations and is preceded by the exposure to several risk factors. Epidemiology has demonstrated that PDAC risk factors may be non-modifiable risks (sex, age, presence of genetic mutations, ethnicity) and modifiable and co-morbidity factors related to the specific habits and lifestyle. Recently it has become evident that obesity and diabetes are two important modifiable risk factors for PDAC. Obesity and diabetes are complex systemic and intertwined diseases and, over the years, experimental evidence indicate that insulin-resistance, alteration of adipokines, especially leptin and adiponectin, oxidative stress and inflammation may play a role in PDAC. Peroxisome proliferator activated receptor-γ (PPARγ) is a nuclear receptor transcription factor that is implicated in the regulation of metabolism, differentiation and inflammation. PPARγ is a key regulator of adipocytes differentiation, regulates insulin and adipokines production and secretion, may modulate inflammation, and it is implicated in PDAC. PPARγ agonists are used in the treatment of diabetes and oxidative stress-associated diseases and have been evaluated for the treatment of PDAC. PPARγ is at the cross-road of diabetes, obesity, and PDAC and it is an interesting target to pharmacologically prevent PDAC in obese and diabetic patients.
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24
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Abstract
The goal for the treatment of patients with diabetes has today shifted from merely reducing glucose concentrations to preventing the natural decline in β-cell function and delay the progression of disease. Pancreatic β-cell dysfunction and decreased β-cell mass are crucial in the development of diabetes. The β-cell defects are the main pathogenesis in patients with type 1 diabetes and are associated with type 2 diabetes as the disease progresses. Recent studies suggest that human pancreatic β-cells have a capacity for increased proliferation according to increased demands for insulin. In humans, β-cell mass has been shown to increase in patients showing insulin-resistance states such as obesity or in pregnancy. This capacity might be useful for identifying new therapeutic strategies to reestablish a functional β-cell mass. In this context, therapeutic approaches designed to increase β-cell mass might prove a significant way to manage diabetes and prevent its progression. This review describes the various β-cell defects that appear in patients with diabetes and outline the mechanisms of β-cell failure. We also review common methods for assessing β-cell function and mass and methodological limitations in vivo. Finally, we discuss the current therapeutic approaches to improve β-cell function and increase β-cell mass.
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Affiliation(s)
- Kyong Yeun Jung
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Kyoung Min Kim
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
| | - Soo Lim
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea
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25
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Abstract
Metabolic syndrome is a disorder based on insulin resistance. Metabolic syndrome is diagnosed by a co-occurrence of three out of five of the following medical conditions: abdominal obesity, elevated blood pressures, elevated glucose, high triglycerides, and low high-density lipoprotein-cholesterol (HDL-C) levels. Clinical implication of metabolic syndrome is that it increases the risk of developing type 2 diabetes and cardiovascular diseases. Prevalence of the metabolic syndrome has increased globally, particularly in the last decade, to the point of being regarded as an epidemic. The prevalence of metabolic syndrome in the USA is estimated to be 34% of adult population. Moreover, increasing rate of metabolic syndrome in developing countries is dramatic. One can speculate that metabolic syndrome is going to induce huge impact on our lives. The metabolic syndrome cannot be treated with a single agent, since it is a multifaceted health problem. A healthy lifestyle including weight reduction is likely most effective in controlling metabolic syndrome. However, it is difficult to initiate and maintain healthy lifestyles, and in particular, with the recidivism of obesity in most patients who lose weight. Next, pharmacological agents that deal with obesity, diabetes, hypertension, and dyslipidemia can be used singly or in combination: anti-obesity drugs, thiazolidinediones, metformin, statins, fibrates, renin-angiotensin system blockers, glucagon like peptide-1 agonists, sodium glucose transporter-2 inhibitors, and some antiplatelet agents such as cilostazol. These drugs have not only their own pharmacologic targets on individual components of metabolic syndrome but some other properties may prove beneficial, i.e. anti-inflammatory and anti-oxidative. This review will describe pathophysiologic features of metabolic syndrome and pharmacologic agents for the treatment of metabolic syndrome, which are currently available.
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Affiliation(s)
- Soo Lim
- Department of Internal Medicine, Seoul National University College of Medicine and Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-city, 463-707, South Korea,
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26
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Hogh KLN, Craig MN, Uy CE, Nygren H, Asadi A, Speck M, Fraser JD, Rudecki AP, Baker RK, Orešič M, Gray SL. Overexpression of PPARγ specifically in pancreatic β-cells exacerbates obesity-induced glucose intolerance, reduces β-cell mass, and alters islet lipid metabolism in male mice. Endocrinology 2014; 155:3843-52. [PMID: 25051434 DOI: 10.1210/en.2014-1076] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The contribution of peroxisomal proliferator-activated receptor (PPAR)-γ agonism in pancreatic β-cells to the antidiabetic actions of thiazolidinediones has not been clearly elucidated. Genetic models of pancreatic β-cell PPARγ ablation have revealed a potential role for PPARγ in β-cell expansion in obesity but a limited role in normal β-cell physiology. Here we overexpressed PPARγ1 or PPARγ2 specifically in pancreatic β-cells of mice subjected to high-fat feeding using an associated adenovirus (β-PPARγ1-HFD and β-PPARγ2-HFD mice). We show β-cell-specific PPARγ1 or PPARγ2 overexpression in diet-induced obese mice exacerbated obesity-induced glucose intolerance with decreased β-cell mass, increased islet cell apoptosis, and decreased plasma insulin compared with obese control mice (β-eGFP-HFD mice). Analysis of islet lipid composition in β-PPARγ2-HFD mice revealed no significant changes in islet triglyceride content and an increase in only one of eight ceramide species measured. Interestingly β-PPARγ2-HFD islets had significantly lower levels of lysophosphatidylcholines, lipid species shown to enhance insulin secretion in β-cells. Gene expression profiling revealed increased expression of uncoupling protein 2 and genes involved in fatty acid transport and β-oxidation. In summary, transgenic overexpression of PPARγ in β-cells in diet-induced obesity negatively impacts whole-animal carbohydrate metabolism associated with altered islet lipid content, increased expression of β-oxidative genes, and reduced β-cell mass.
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Affiliation(s)
- K-Lynn N Hogh
- Northern Medical Program (K.N.H., M.N.C., C.E.U., J.D.F., A.P.R., S.L.G.), University of Northern British Columbia, Prince George, British Columbia, Canada V2N 4Z9; Department of Cellular and Physiological Sciences and Faculty of Medicine (A.A., R.K.B.), University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4; VTT Technical Research Centre of Finland (H.N., M.O.), Espoo FI-02044, Finland; Steno Diabetes Center A/S (H.N., M.O.), Gentofte, Denmark; and Child and Family Research Institute (M.S.), Vancouver, British Columbia, Canada V6T 1Z1
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Zhou G, Sinnett-Smith J, Liu SH, Yu J, Wu J, Sanchez R, Pandol SJ, Abrol R, Nemunaitis J, Rozengurt E, Brunicardi FC. Down-regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5: a novel mechanism for inhibition of cellular proliferation and insulin secretion by somatostatin. Front Physiol 2014; 5:226. [PMID: 25009500 PMCID: PMC4069483 DOI: 10.3389/fphys.2014.00226] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 05/31/2014] [Indexed: 01/29/2023] Open
Abstract
Somatostatin (SST) is a regulatory peptide and acts as an endogenous inhibitory regulator of the secretory and proliferative responses of target cells. SST’s actions are mediated by a family of seven transmembrane domain G protein-coupled receptors that comprise five distinct subtypes (SSTR1-5). SSTR5 is one of the major SSTRs in the islets of Langerhans. Homeodomain-containing transcription factor pancreatic and duodenal homeobox-1 (PDX-1) is essential for pancreatic development, β cell differentiation, maintenance of normal β cell functions in adults and tumorigenesis. Recent studies show that SSTR5 acts as a negative regulator for PDX-1 expression and that SSTR5 mediates somatostatin’s inhibitory effect on cell proliferation and insulin expression/excretion through down-regulating PDX-1 expression. SSTR5 exerts its inhibitory effect on PDX-1 expression at both the transcriptional level by down-regulating PDX-1 mRNA and the post-translational level by enhancing PDX-1 ubiquitination. Identification of PDX-1 as a transcriptional target for SSTR5 may help in guiding the choice of therapeutic cancer treatments.
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Affiliation(s)
- Guisheng Zhou
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Jim Sinnett-Smith
- CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Shi-He Liu
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Juehua Yu
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - James Wu
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Robbi Sanchez
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - Stephen J Pandol
- CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; Department of Medicine at Cedars Sinai Medical Center Los Angeles, CA, USA ; Veterans Affairs Los Angeles, CA, USA
| | - Ravinder Abrol
- Materials and Process Simulation Center, California Institute of Technology Pasadena, CA, USA
| | - John Nemunaitis
- Gradalis, Inc., Dallas, TX, USA ; Mary Crowley Cancer Research Centers Dallas, TX, USA
| | - Enrique Rozengurt
- CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; Department of Medicine, David Geffen School of Medicine at University of California Los Angeles, CA, USA
| | - F Charles Brunicardi
- Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California Los Angeles, CA, USA ; CURE: Digestive Disease Research Center, David Geffen School of Medicine at University of California Los Angeles, CA, USA
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Chen M, Hu C, Zhang R, Jiang F, Wang J, Peng D, Tang S, Sun X, Yan J, Luo Y, Bao Y, Jia W. Association of PAX4 genetic variants with oral antidiabetic drugs efficacy in Chinese type 2 diabetes patients. THE PHARMACOGENOMICS JOURNAL 2014; 14:488-92. [PMID: 24752311 DOI: 10.1038/tpj.2014.18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 02/14/2014] [Accepted: 02/26/2014] [Indexed: 11/09/2022]
Abstract
The aim of this study was to investigate the association of PAX4 variants with therapeutic effect of oral antidiabetic drugs in Chinese type 2 diabtes mellitus (T2DM) patients. A total of 209 newly diagnosed T2DM patients were randomly assigned to treatment with repaglinide or rosiglitazone for 48 weeks, and the therapeutic effects were compared. In the rosiglitazone cohort, rs6467136 GA+AA carriers showed greater decrease in 2-h glucose levels (P=0.0063) and higher cumulative attainment rates of target 2-h glucose levels (Plog rank=0.0093) than GG homozygotes. In the subgroup with defective β-cell function, rs6467136 GA+AA carriers exhibited greater decrements of 2-h glucose level and improvement of homeostasis model assessment of insulin resistance (P=0.0143). Moreover, GA+AA carriers were more likely to attain the target fasting and 2-h glucose level (Plog rank=0.0091 and 0.007, respectively). However, these single-nucleotide polymorphisms showed no effect on repaglinide efficacy. In conclusion, PAX4 variant rs6467136 was associated with the therapeutic effect of rosiglitazone in Chinese T2DM patients.
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Affiliation(s)
- M Chen
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - C Hu
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - R Zhang
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - F Jiang
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - J Wang
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - D Peng
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - S Tang
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - X Sun
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - J Yan
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - Y Luo
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - Y Bao
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
| | - W Jia
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Clinical Center for Metabolic Disease, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Diabetes Institute, Shanghai, China
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So WY, Cheng Q, Chen L, Evans-Molina C, Xu A, Lam KS, Leung PS. High glucose represses β-klotho expression and impairs fibroblast growth factor 21 action in mouse pancreatic islets: involvement of peroxisome proliferator-activated receptor γ signaling. Diabetes 2013; 62:3751-9. [PMID: 23897951 PMCID: PMC3806592 DOI: 10.2337/db13-0645] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Circulating fibroblast growth factor 21 (FGF21) levels are elevated in diabetic subjects and correlate directly with abnormal glucose metabolism, while pharmacologically administered FGF21 can ameliorate hyperglycemia. The pancreatic islet is an FGF21 target, yet the actions of FGF21 in the islet under normal and diabetic conditions are not fully understood. This study investigated the effects of high glucose on islet FGF21 actions in a diabetic mouse model by investigating db/db mouse islet responses to exogenous FGF21, the direct effects of glucose on FGF21 signaling, and the involvement of peroxisome proliferator-activated receptor γ (PPARγ) in FGF21 pathway activation. Results showed that both adult db/db mouse islets and normal islets treated with high glucose ex vivo displayed reduced β-klotho expression, resistance to FGF21, and decreased PPARγ expression. Rosiglitazone, an antidiabetic PPARγ ligand, ameliorated these effects. Our data indicate that hyperglycemia in type 2 diabetes mellitus may lead to FGF21 resistance in pancreatic islets, probably through reduction of PPARγ expression, which provides a novel mechanism for glucose-mediated islet dysfunction.
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Affiliation(s)
- Wing Yan So
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Qianni Cheng
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Lihua Chen
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Carmella Evans-Molina
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Aimin Xu
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
| | - Karen S.L. Lam
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
| | - Po Sing Leung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Corresponding author: Po Sing Leung,
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Cheng AS, Cheng YH, Chang TL. Resveratrol protects RINm5F pancreatic cells from methylglyoxal-induced apoptosis. J Funct Foods 2013. [DOI: 10.1016/j.jff.2013.07.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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Lee BH, Lee CC, Cheng YH, Chang WC, Hsu WH, Wu SC. Graptopetalum paraguayense and resveratrol ameliorates carboxymethyllysine (CML)-induced pancreas dysfunction and hyperglycemia. Food Chem Toxicol 2013; 62:492-8. [PMID: 24036142 DOI: 10.1016/j.fct.2013.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 08/27/2013] [Accepted: 09/06/2013] [Indexed: 01/02/2023]
Abstract
Hyperglycemia is associated with advanced glycation end products (AGEs). Recently, AGEs were found to cause pancreatic damage, oxidative stress, and hyperglycemia through the AGE receptor. Carboxymethyllysine (CML) is an AGE but whether it induces pancreatic dysfunction remains unclear. Graptopetalum paraguayense, a vegetable consumed in Taiwan, has been used in folk medicine and is an antioxidant that protects against liver damage. We investigated the protective properties of G. paraguayense 95% ethanol extracts (GPEs) against CML-induced pancreatic damage. The results indicated that resveratrol, GPE, and gallic acid (the active compound of GPE) increased insulin synthesis via upregulation of pancreatic peroxisome proliferator activated-receptor-γ (PPARγ) and pancreatic-duodenal homeobox-1 (PDX-1) but inhibited the expression of CML-mediated CCAAT/enhancer binding protein-β (C/EBPβ), a negative regulator of insulin production. Moreover, resveratrol and GPE also strongly activated nuclear factor-erythroid 2-related factor 2 (Nrf2) to attenuate oxidative stress and improve insulin sensitivity in the liver and muscle of CML-injected C57BL/6 mice and resulted in reduced blood glucose levels. Taken together, these findings suggested that GPE and gallic acid could potentially be used as a food supplement to protect against pancreatic damage and the development of diabetes.
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Affiliation(s)
- Bao-Hong Lee
- Department of Food Science, National Chiayi University, Taiwan, ROC.
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32
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Hsu WH, Lee BH, Li CH, Hsu YW, Pan TM. Monascin and AITC attenuate methylglyoxal-induced PPARγ phosphorylation and degradation through inhibition of the oxidative stress/PKC pathway depending on Nrf2 activation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:5996-6006. [PMID: 23731245 DOI: 10.1021/jf401197r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Abnormal cellular accumulation of the dicarbonyl metabolite methylglyoxal (MG) results in cell damage, inflammation, and oxidative stress. It is also associated with increased protein linkage to form advanced glycation end products (AGEs) or induce DNA strand breaks. The association between peroxisome proliferator-activated receptor-γ (PPARγ) and nuclear factor-erythroid 2-related factor 2 (Nrf2) is unclear. This study investigated Nrf2 activator protection against PPARγ phosphorylation and degradation to maintain pancreatic function. MG was used at a noncytotoxic concentration (200 μM) to induce protein kinase C (PKC) and PPARγ phosphorylation in pancreatic RINm5F cells. For in vivo studies, MG (60 mg/kg bw) was intraperitoneally (IP) injected into Balb/C mice for 28 d to induce pancreas damage, at which point we investigated the effect of monascin protection (PPARγ and Nrf2 activator), rosiglitazone (PPARγ activator), allyl isothiocyanate (AITC; Nrf2 activator), or N-acetylcysteine (NAC) on pancreatic function. The in vitro and in vivo results indicated that MG leads to marked PPARγ phosphorylation (serine 82); this effect led to reduction in pancreatic and duodenal homeobox-1 (PDX-1), glucokinase (GCK), and insulin expression. However, monascin and rosiglitazone may protect PPARγ degradation by elevating PDX-1, GCK, and as a result, insulin expression. Monascin and AITC can attenuate PKC activation to suppress PPARγ phosphorylation caused by oxidative stress through the Nrf2 pathway. Similarly, the N-acetylcysteine (NAC) antioxidant also improved oxidative stress and pancreatic function. This study examined whether MG caused impairment of PDX-1, GCK, and insulin through PPARγ phosphorylation and degradation. MG and AGE accumulation improved on Nrf2 activation, thereby protecting against pancreas damage. Taken together, PPARγ activation maintained pancreatic PDX-1, GCK, and insulin expression levels to regulate blood glucose levels.
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Affiliation(s)
- Wei-Hsuan Hsu
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University , No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
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Gupta D, Leahy AA, Monga N, Peshavaria M, Jetton TL, Leahy JL. Peroxisome proliferator-activated receptor γ (PPARγ) and its target genes are downstream effectors of FoxO1 protein in islet β-cells: mechanism of β-cell compensation and failure. J Biol Chem 2013; 288:25440-25449. [PMID: 23788637 DOI: 10.1074/jbc.m113.486852] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The molecular mechanisms and signaling pathways that drive islet β-cell compensation and failure are not fully resolved. We have used in vitro and in vivo systems to show that FoxO1, an integrator of metabolic stimuli, inhibits PPARγ expression in β-cells, thus transcription of its target genes (Pdx1, glucose-dependent insulinotropic polypeptide (GIP) receptor, and pyruvate carboxylase) that are important regulators of β-cell function, survival, and compensation. FoxO1 inhibition of target gene transcription is normally relieved when upstream activation induces its translocation from the nucleus to the cytoplasm. Attesting to the central importance of this pathway, islet expression of PPARγ and its target genes was enhanced in nondiabetic insulin-resistant rats and markedly reduced with diabetes induction. Insight into the impaired PPARγ signaling with hyperglycemia was obtained with confocal microscopy of pancreas sections that showed an intense nuclear FoxO1 immunostaining pattern in the β-cells of diabetic rats in contrast to the nuclear and cytoplasmic FoxO1 in nondiabetic rats. These findings suggest a FoxO1/PPARγ-mediated network acting as a core component of β-cell adaptation to metabolic stress, with failure of this response from impaired FoxO1 activation causing or exacerbating diabetes.
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Affiliation(s)
- Dhananjay Gupta
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Averi A Leahy
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Navjot Monga
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Mina Peshavaria
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Thomas L Jetton
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Jack L Leahy
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont 05405.
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Ahmadian M, Suh JM, Hah N, Liddle C, Atkins AR, Downes M, Evans RM. PPARγ signaling and metabolism: the good, the bad and the future. Nat Med 2013; 19:557-66. [PMID: 23652116 PMCID: PMC3870016 DOI: 10.1038/nm.3159] [Citation(s) in RCA: 1545] [Impact Index Per Article: 140.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 03/06/2013] [Indexed: 11/09/2022]
Abstract
Thiazolidinediones (TZDs) are potent insulin sensitizers that act through the nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ) and are highly effective oral medications for type 2 diabetes. However, their unique benefits are shadowed by the risk for fluid retention, weight gain, bone loss and congestive heart failure. This raises the question as to whether it is possible to build a safer generation of PPARγ-specific drugs that evoke fewer side effects while preserving insulin-sensitizing potential. Recent studies that have supported the continuing physiologic and therapeutic relevance of the PPARγ pathway also provide opportunities to develop newer classes of molecules that reduce or eliminate adverse effects. This review highlights key advances in understanding PPARγ signaling in energy homeostasis and metabolic disease and also provides new explanations for adverse events linked to TZD-based therapy.
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Affiliation(s)
- Maryam Ahmadian
- Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California, USA
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PPARγ activation attenuates glycated-serum induced pancreatic beta-cell dysfunction through enhancing Pdx1 and Mafa protein stability. PLoS One 2013; 8:e56386. [PMID: 23424659 PMCID: PMC3570423 DOI: 10.1371/journal.pone.0056386] [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] [Received: 07/16/2012] [Accepted: 01/10/2013] [Indexed: 12/31/2022] Open
Abstract
Pancreatic-duodenal homeobox-1 (Pdx1) and v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (Mafa) play important roles in sustaining the pancreatic beta-cell differentiation phenotype. Peroxisome proliferator-activated receptor-γ (PPARγ) is also a regulator of cell differentiation. Our previous study revealed that glycated serum (GS) causes beta-cell dedifferentiation by down-regulating beta-cell specific genes, such as insulin and Pdx1. Here, we show that GS enhanced the cellular accumulation of ubiquitin-conjugated proteins, including Pdx1 and Mafa, in pancreatic beta-cells. Pharmacologic inhibition of proteolytic activity restored the protein levels of Pdx1 and Mafa, whereas inhibition of de novo protein synthesis accelerated their degradation. These findings suggest that both Pdx1 and Mafa are regulated at the post-transcriptional level. We further show that activation of PPARγ could restore GS-induced reduction of Pdx1 and Mafa protein levels, leading to improved insulin secretion and synthesis. Moreover, ectopic expression of Bcl-xl, a mitochondrial regulator, also restored Pdx1 and Mafa protein levels, linking mitochondrial function to Pdx1 and Mafa stability. Taken together, our results identify a key role of PPARγ in regulating pancreatic beta-cell function by improving the stability of Pdx1 and Mafa proteins.
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Kim HS, Hwang YC, Koo SH, Park KS, Lee MS, Kim KW, Lee MK. PPAR-γ activation increases insulin secretion through the up-regulation of the free fatty acid receptor GPR40 in pancreatic β-cells. PLoS One 2013; 8:e50128. [PMID: 23372643 PMCID: PMC3553172 DOI: 10.1371/journal.pone.0050128] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 10/16/2012] [Indexed: 11/18/2022] Open
Abstract
Background It has been reported that peroxisome proliferator-activated receptor (PPAR)-γ and their synthetic ligands have direct effects on pancreatic β-cells. We investigated whether PPAR-γ activation stimulates insulin secretion through the up-regulation of GPR40 in pancreatic β-cells. Methods Rat insulinoma INS-1 cells and primary rat islets were treated with rosiglitazone (RGZ) and/or adenoviral PPAR-γ overexpression. OLETF rats were treated with RGZ. Results PPAR-γ activation with RGZ and/or adenoviral PPAR-γ overexpression increased free fatty acid (FFA) receptor GPR40 expression, and increased insulin secretion and intracellular calcium mobilization, and was blocked by the PLC inhibitors, GPR40 RNA interference, and GLUT2 RNA interference. As a downstream signaling pathway of intracellular calcium mobilization, the phosphorylated levels of CaMKII and CREB, and the downstream IRS-2 and phospho-Akt were significantly increased. Despite of insulin receptor RNA interference, the levels of IRS-2 and phospho-Akt was still maintained with PPAR-γ activation. In addition, the β-cell specific gene expression, including Pdx-1 and FoxA2, increased in a GPR40- and GLUT2-dependent manner. The levels of GPR40, phosphorylated CaMKII and CREB, and β-cell specific genes induced by RGZ were blocked by GW9662, a PPAR-γ antagonist. Finally, PPAR-γ activation up-regulated β-cell gene expressions through FoxO1 nuclear exclusion, independent of the insulin signaling pathway. Based on immunohistochemical staining, the GLUT2, IRS-2, Pdx-1, and GPR40 were more strongly expressed in islets from RGZ-treated OLETF rats compared to control islets. Conclusion These observations suggest that PPAR-γ activation with RGZ and/or adenoviral overexpression increased intracellular calcium mobilization, insulin secretion, and β-cell gene expression through GPR40 and GLUT2 gene up-regulation.
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Affiliation(s)
- Hyo-Sup Kim
- Division of Endocrinology and Metabolism, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - You-Cheol Hwang
- Division of Endocrinology and Metabolism, Department of Medicine, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea
| | - Seung-Hoi Koo
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Kyong Soo Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Myung-Shik Lee
- Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Kwang-Won Kim
- Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Moon-Kyu Lee
- Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
- * E-mail:
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Hsu WH, Lu SS, Lee BH, Hsu YW, Pan TM. Monacolin K and monascin attenuated pancreas impairment and hyperglycemia induced by advanced glycation endproducts in BALB/c mice. Food Funct 2013; 4:1742. [DOI: 10.1039/c3fo60268k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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Iglesias J, Barg S, Vallois D, Lahiri S, Roger C, Yessoufou A, Pradevand S, McDonald A, Bonal C, Reimann F, Gribble F, Debril MB, Metzger D, Chambon P, Herrera P, Rutter GA, Prentki M, Thorens B, Wahli W. PPARβ/δ affects pancreatic β cell mass and insulin secretion in mice. J Clin Invest 2012; 122:4105-17. [PMID: 23093780 DOI: 10.1172/jci42127] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 07/19/2012] [Indexed: 12/30/2022] Open
Abstract
PPARβ/δ protects against obesity by reducing dyslipidemia and insulin resistance via effects in muscle, adipose tissue, and liver. However, its function in pancreas remains ill defined. To gain insight into its hypothesized role in β cell function, we specifically deleted Pparb/d in the epithelial compartment of the mouse pancreas. Mutant animals presented increased numbers of islets and, more importantly, enhanced insulin secretion, causing hyperinsulinemia. Gene expression profiling of pancreatic β cells indicated a broad repressive function of PPARβ/δ affecting the vesicular and granular compartment as well as the actin cytoskeleton. Analyses of insulin release from isolated PPARβ/δ-deficient islets revealed an accelerated second phase of glucose-stimulated insulin secretion. These effects in PPARβ/δ-deficient islets correlated with increased filamentous actin (F-actin) disassembly and an elevation in protein kinase D activity that altered Golgi organization. Taken together, these results provide evidence for a repressive role for PPARβ/δ in β cell mass and insulin exocytosis, and shed a new light on PPARβ/δ metabolic action.
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Affiliation(s)
- José Iglesias
- Center for Integrative Genomics, National Research Center Frontiers in Genetics, University of Lausanne, Lausanne, Switzerland
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Welters HJ, El Ouaamari A, Kawamori D, Meyer J, Hu J, Smith DM, Kulkarni RN. Rosiglitazone promotes PPARγ-dependent and -independent alterations in gene expression in mouse islets. Endocrinology 2012; 153:4593-9. [PMID: 22807489 PMCID: PMC3512010 DOI: 10.1210/en.2012-1243] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The glitazone class of insulin-sensitizing agents act, in part, by the activation of peroxisome proliferator-activated receptor (PPAR)-γ in adipocytes. However, it is unclear whether the expression of PPARγ in the islets is essential for their potential β-cell-sparing properties. To investigate the in vivo effects of rosiglitazone on β-cell biology, we used an inducible, pancreatic and duodenal homeobox-1 enhancer element-driven, Cre recombinase to knockout PPARγ expression specifically in adult β-cells (PPARgKO). Subjecting the PPARgKO mice to a chow diet led to virtually undetectable changes in glucose or insulin sensitivity, which was paralleled by minimal changes in islet gene expression. Similarly, challenging the mutant mice with a high-fat diet and treatment with rosiglitazone did not alter insulin sensitivity, glucose-stimulated insulin secretion, islet size, or proliferation in the knockout mice despite PPARγ-dependent and -independent changes in islet gene expression. These data suggest that PPARγ expression in the β-cells is unlikely to be directly essential for normal β-cell function or the insulin-sensitizing actions of rosiglitazone.
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Affiliation(s)
- Hannah J Welters
- Peninsula College of Medicine and Dentistry, University of Exeter, Exeter EX2 5DW, United Kingdom.
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Liang J, Leung KK, Lam SY, Leung PS. Combined treatment with a dipeptidyl peptidase-IV inhibitor (sitagliptin) and an angiotensin II type 1 receptor blocker (losartan) promotes islet regeneration via enhanced differentiation of pancreatic progenitor cells. Diabetes Obes Metab 2012; 14:842-51. [PMID: 22519909 DOI: 10.1111/j.1463-1326.2012.01612.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM The existence of pancreatic progenitor cells (PPCs) with differentiation capacity in the adult pancreas has rendered that promotion of islet regeneration is feasible. The dipeptidyl peptidase-IV inhibitor sitagliptin and the angiotensin II type 1 receptor (AT(1) receptor) blocker losartan have a common target action in the pancreata. Thus, we evaluated the synergistic/additive effects of these two drugs on the differentiation of islet progenitors. METHODS The acute and chronic effects of sitagliptin and losartan, individually or in combination, on islet regeneration in vivo were investigated by using a streptozotocin-induced type 1 diabetes mouse model. Their effects were also examined on an in vitro PPCs model derived from human foetal pancreas. RESULTS A chronic combination treatment enhanced glucose tolerance in diabetic mice associated with an increased ratio of β cells to islet; an acute combination treatment resulted in a marked increase in the production of neurogenin 3 (NGN3(+)) cells in proximity to CK7(+) ductal cell and an increased presence of insulin(+) /CK7(+) cells. The in vitro study revealed that a combination treatment significantly enhanced mRNA expression of NGN3, NKX6.1 and PDX-1 during PPCs differentiation into human islet-like cell clusters (ICCs). Despite no apparent changes in insulin release, the combined treatment resulted in increasing production of peroxisome proliferator-activated receptor γ (PPARγ) during PPC differentiation. CONCLUSIONS These data indicate that combined sitagliptin-losartan treatment can improve islet function by promoting the differentiation of PPCs into ICCs, perhaps via a mechanism involving PPARγ production, and could thereby, contribute to islet regeneration.
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Affiliation(s)
- J Liang
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Poulsen LLC, Siersbæk M, Mandrup S. PPARs: fatty acid sensors controlling metabolism. Semin Cell Dev Biol 2012; 23:631-9. [PMID: 22273692 DOI: 10.1016/j.semcdb.2012.01.003] [Citation(s) in RCA: 336] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 01/09/2012] [Indexed: 12/13/2022]
Abstract
The peroxisome proliferator activated receptors (PPARs) are nuclear receptors that play key roles in the regulation of lipid metabolism, inflammation, cellular growth, and differentiation. The receptors bind and are activated by a broad range of fatty acids and fatty acid derivatives and they thereby serve as major transcriptional sensors of fatty acids. Here we review the function, regulation, and mechanism of the different PPAR subtypes with special emphasis on their role in the regulation of lipid metabolism.
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Affiliation(s)
- Lars la Cour Poulsen
- University of Southern Denmark, Department of Biochemistry and Molecular Biology, Campusvej 55, DK-5230, Odense M, Denmark.
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Kono T, Ahn G, Moss DR, Gann L, Zarain-Herzberg A, Nishiki Y, Fueger PT, Ogihara T, Evans-Molina C. PPAR-γ activation restores pancreatic islet SERCA2 levels and prevents β-cell dysfunction under conditions of hyperglycemic and cytokine stress. Mol Endocrinol 2012; 26:257-71. [PMID: 22240811 DOI: 10.1210/me.2011-1181] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The maintenance of intracellular Ca(2+) homeostasis in the pancreatic β-cell is closely regulated by activity of the sarco-endoplasmic reticulum Ca(2+) ATPase (SERCA) pump. Our data demonstrate a loss of β-cell SERCA2b expression in several models of type 2 diabetes including islets from db/db mice and cadaveric diabetic human islets. Treatment of 832/13 rat INS-1-derived cells with 25 mm glucose and the proinflammatory cytokine IL-1β led to a similar loss of SERCA2b expression, which was prevented by treatment with the peroxisome proliferator-activated receptor (PPAR)-γ agonist, pioglitazone. Pioglitazone was able to also protect against hyperglycemia and cytokine-induced elevations in cytosolic Ca(2+) levels, insulin-secretory defects, and cell death. To determine whether PPAR-γ was a direct transcriptional regulator of the SERCA2 gene, luciferase assays were performed and showed that a -259 bp region is sufficient to confer PPAR-γ transactivation; EMSA and chromatin immunoprecipitation experiments confirmed that PPAR-γ directly binds a PPAR response element in this proximal region. We next sought to characterize the mechanisms by which SERCA2b was down-regulated. INS-1 cells were exposed to high glucose and IL-1β in time course experiments. Within 2 h of exposure, activation of cyclin-dependent kinase 5 (CDK5) was observed and correlated with increased serine-273 phosphorylation of PPAR-γ and loss of SERCA2 protein expression, findings that were prevented by pioglitazone and roscovitine, a pharmacological inhibitor of CDK5. We conclude that pioglitazone modulates SERCA2b expression through direct transcriptional regulation of the gene and indirectly through prevention of CDK5-induced phosphorylation of PPAR-γ.
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Affiliation(s)
- Tatsuyoshi Kono
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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Xie W, Zhao Y, Gu D, Du L, Cai G, Zhang Y. Scorpion in Combination with Gypsum: Novel Antidiabetic Activities in Streptozotocin-Induced Diabetic Mice by Up-Regulating Pancreatic PPARγ and PDX-1 Expressions. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2011; 2011:683561. [PMID: 21799688 PMCID: PMC3136920 DOI: 10.1093/ecam/neq031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Accepted: 03/15/2010] [Indexed: 01/27/2023]
Abstract
The management of diabetes without any side effects remains a challenge in medicine. In this study, antidiabetic activity and the mechanism of action of scorpion combined with gypsum (SG) were investigated. Streptozotocin-induced diabetic mice were orally administrated with scorpion (200 mg kg(-1) per day) in combination with gypsum (200 mg kg(-1) per day) for 5 weeks. SG treatment resulted in decreased body weight, blood glucose and lipid levels, and increased serum and pancreatic insulin levels in diabetic mice. Furthermore, SG significantly increased the number and volume of beta cells in the Islets of Langerhans and promoted peroxisome proliferator-activated receptor gamma and pancreatic duodenal homeobox 1 expressions in pancreatic tissues. However, scorpion or gypsum alone had no significant effect in this animal model. Metformin showed a slight or moderate effect in this diabetic model, but this effect was weak compared with that of SG. Taken together, SG showed a new antidiabetic effect in streptozotocin-induced diabetic mice. This effect may possibly be involved in enhancing beta-cell regeneration and promoting insulin secretion by targeting PPARγ and PDX-1. Moreover, this new effect of SG offers a promising step toward the treatment of diabetic patients with beta-cell failure as a complementary and alternative medicine.
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Affiliation(s)
- Weidong Xie
- Life Science Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
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Gupta D, Kono T, Evans-Molina C. The role of peroxisome proliferator-activated receptor γ in pancreatic β cell function and survival: therapeutic implications for the treatment of type 2 diabetes mellitus. Diabetes Obes Metab 2010; 12:1036-47. [PMID: 20977574 PMCID: PMC3764483 DOI: 10.1111/j.1463-1326.2010.01299.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The pathogenesis of type 2 diabetes mellitus involves both peripheral insulin resistance and dysfunctional insulin secretion from the pancreatic β cell. Currently, there is intense research focus on delineating the etiologies of pancreatic β cell dysfunction in type 2 diabetes. However, there remains an unmet clinical need to establish therapeutic guidelines and strategies that emphasize the preservation of pancreatic β cell function in at-risk and affected individuals. Thiazolidinediones are orally active agents approved for use in type 2 diabetes and act as agonists of the nuclear hormone receptor PPAR-γ. These drugs improve insulin sensitivity, but there is also a growing appreciation of PPAR-γ actions within the β cell. PPAR-γ has been shown to regulate directly key β cell genes involved in glucose sensing, insulin secretion and insulin gene transcription. Further, pharmacologic PPAR-γ activation has been shown to protect against glucose-, lipid-, cytokine- and islet amyloid polypeptide (IAPP)-induced activation of numerous stress pathways. This article will review the mechanisms by which PPAR-γ activation acts to maintain β cell function and survival in type 2 diabetes mellitus and highlight some of the current controversies in this field.
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Affiliation(s)
- D Gupta
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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45
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Honig G, Liou A, Berger M, German MS, Tecott LH. Precise pattern of recombination in serotonergic and hypothalamic neurons in a Pdx1-cre transgenic mouse line. J Biomed Sci 2010; 17:82. [PMID: 20950489 PMCID: PMC2966455 DOI: 10.1186/1423-0127-17-82] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 10/17/2010] [Indexed: 11/25/2022] Open
Abstract
Background Multicellular organisms are characterized by a remarkable diversity of morphologically distinct and functionally specialized cell types. Transgenic techniques for the manipulation of gene expression in specific cellular populations are highly useful for elucidating the development and function of these cellular populations. Given notable similarities in developmental gene expression between pancreatic β-cells and serotonergic neurons, we examined the pattern of Cre-mediated recombination in the nervous system of a widely used mouse line, Pdx1-cre (formal designation, Tg(Ipf1-cre)89.1Dam), in which the expression of Cre recombinase is driven by regulatory elements upstream of the pdx1 (pancreatic-duodenal homeobox 1) gene. Methods Single (hemizygous) transgenic mice of the pdx1-creCre/0 genotype were bred to single (hemizygous) transgenic reporter mice (Z/EG and rosa26R lines). Recombination pattern was examined in offspring using whole-mount and sectioned histological preparations at e9.5, e10.5, e11.5, e16.5 and adult developmental stages. Results In addition to the previously reported pancreatic recombination, recombination in the developing nervous system and inner ear formation was observed. In the central nervous system, we observed a highly specific pattern of recombination in neuronal progenitors in the ventral brainstem and diencephalon. In the rostral brainstem (r1-r2), recombination occurred in newborn serotonergic neurons. In the caudal brainstem, recombination occurred in non-serotonergic cells. In the adult, this resulted in reporter expression in the vast majority of forebrain-projecting serotonergic neurons (located in the dorsal and median raphe nuclei) but in none of the spinal cord-projecting serotonergic neurons of the caudal raphe nuclei. In the adult caudal brainstem, reporter expression was widespread in the inferior olive nucleus. In the adult hypothalamus, recombination was observed in the arcuate nucleus and dorsomedial hypothalamus. Recombination was not observed in any other region of the central nervous system. Neuronal expression of endogenous pdx1 was not observed. Conclusions The Pdx1-cre mouse line, and the regulatory elements contained in the corresponding transgene, could be a valuable tool for targeted genetic manipulation of developing forebrain-projecting serotonergic neurons and several other unique neuronal sub-populations. These results suggest that investigators employing this mouse line for studies of pancreatic function should consider the possible contributions of central nervous system effects towards resulting phenotypes.
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Affiliation(s)
- Gerard Honig
- Neuroscience Graduate Program, University of California San Francisco, San Francisco, CA, USA.
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AMPK enhances the expression of pancreatic duodenal homeobox-1 via PPARalpha, but not PPARgamma, in rat insulinoma cell line INS-1. Acta Pharmacol Sin 2010; 31:963-9. [PMID: 20644547 DOI: 10.1038/aps.2010.78] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
AIM To investigate whether AMP-activated protein kinase (AMPK) regulates the expression of pancreatic duodenal homeobox-1 (PDX-1), a beta-cell-specific transcription factor and whether PPARalpha/gamma is involved in the regulation of pancreatic beta-cell lines after acute stimulation. METHODS Rat insulinoma cell line INS-1 was treated with an activator (AICAR) or inhibitor (Compound C) of AMPK as well as inhibitors of PPARs (MK886 to PPARalpha and BADGE to PPARgamma). The mRNA levels of PDX-1, PPARalpha and PPARgamma were measured using real-time RT-PCR, and Western blotting was used to detect the protein expression of these factors. RESULTS Activation of AMPK by AICAR induced significantly increased the expression of PDX-1, and this increase was abrogated when AMPK was inactivated by Compound C. Similarly, the expression of PPARalpha and PPARgamma was also increased by AICAR or decreased by Compound C. However AMPK activation did not increase nuclear PDX-1 protein levels when PPARalpha was inhibited. In contrast, AMPK activation still up-regulated PDX-1 protein levels during PPARgamma inhibition. Additionally, PPARalpha activation induced by fenofibrate significantly enhanced nuclear PDX-1 protein expression. CONCLUSION AMPK regulates the expression of PDX-1 at both the transcriptional and protein levels, and PPARalpha may be acutely involved in the regulation of INS-1 cells.
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Guo H, Zhang XJ, Wang F, Wang Y, Shen Y, Zhao JJ, Gao L. Suppression effects of AICAR on insulin secretion involved in peroxisome proliferator-activated receptor gamma changes in INS-1 cells. J Endocrinol Invest 2010; 33:465-71. [PMID: 20101096 DOI: 10.1007/bf03346626] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND AMP-activated protein kinase (AMPK) activation is known to attenuate glucose-stimulated insulin secretion (GSIS) in pancreatic beta cells. However, the underlying mechanisms are poorly understood. The purpose of this study was to examine the effects of AMPK activation on insulin secretion and to determine whether peroxisome proliferator-activated receptors (PPAR) are involved in the effects on INS-1 cells. METHODS INS-1 cells, insulinoma cell lines, were treated with an activator (AICAR) or inhibitor (Compound C) of AMPK as well as inhibitors of PPAR [MK886 and biphenol A diglycidyl ether (BADGE)] for different treatment times. RESULTS AICAR-induced AMPK activation significantly attenuated GSIS as well as insulin content. Meanwhile, AMPK activation increased the mRNA levels of both PPARalpha and PPARgamma. However, with regard to DNA binding, AMPK activation upregulated PPARgamma only, and it was possible to reduce the increment with the AMPK inhibitor. Moreover, the AICAR-induced suppression of insulin secretion can be counteracted by the PPARgamma inhibitor, BADGE but not the PPARalpha inhibitor. CONCLUSIONS AICAR-induced glucose-stimulated insulin secretion reduction correlates mainly with PPARgamma changes.
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Affiliation(s)
- H Guo
- Central Laboratory, Provincial Hospital affiliated to Shandong University, No. 324, Jing 5 Road, Jinan, 250021, China.
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Liu Z, Habener JF. Wnt signaling in pancreatic islets. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:391-419. [PMID: 20217507 DOI: 10.1007/978-90-481-3271-3_17] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The Wnt signaling pathway is critically important not only for stem cell amplification, differentiation, and migration, but also is important for organogenesis and the development of the body plan. Beta-catenin/TCF7L2-dependent Wnt signaling (the canonical pathway) is involved in pancreas development, islet function, and insulin production and secretion. The glucoincretin hormone glucagon-like peptide-1 and the chemokine stromal cell-derived factor-1 modulate canonical Wnt signaling in beta-cells which is obligatory for their mitogenic and cytoprotective actions. Genome-wide association studies have uncovered 19 gene loci that confer susceptibility for the development of type 2 diabetes. At least 14 of these diabetes risk alleles encode proteins that are implicated in islet growth and functioning. Seven of them are either components of, or known target genes for, Wnt signaling. The transcription factor TCF7L2 is particularly strongly associated with risk for diabetes and appears to be fundamentally important in both canonical Wnt signaling and beta-cell functioning. Experimental loss of TCF7L2 function in islets and polymorphisms in TCF7L2 alleles in humans impair glucose-stimulated insulin secretion, suggesting that perturbations in the Wnt signaling pathway may contribute substantially to the susceptibility for, and pathogenesis of, type 2 diabetes. This review focuses on considerations of the hormonal regulation of Wnt signaling in islets and implications for mutations in components of the Wnt signaling pathway as a source for risk-associated alleles for type 2 diabetes.
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Affiliation(s)
- Zhengyu Liu
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston, MA 02114, USA.
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Gupta D, Peshavaria M, Monga N, Jetton TL, Leahy JL. Physiologic and pharmacologic modulation of glucose-dependent insulinotropic polypeptide (GIP) receptor expression in beta-cells by peroxisome proliferator-activated receptor (PPAR)-gamma signaling: possible mechanism for the GIP resistance in type 2 diabetes. Diabetes 2010; 59:1445-50. [PMID: 20332343 PMCID: PMC2874705 DOI: 10.2337/db09-1655] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE We previously showed that peroxisome proliferator-activated receptor (PPAR)-gamma in beta-cells regulates pdx-1 transcription through a functional PPAR response element (PPRE). Gene Bank blast for a homologous nucleotide sequence revealed the same PPRE within the rat glucose-dependent insulinotropic polypeptide receptor (GIP-R) promoter sequence. We investigated the role of PPARgamma in GIP-R transcription. RESEARCH DESIGN AND METHODS Chromatin immunoprecipitation assay, siRNA, and luciferase gene transcription assay in INS-1 cells were performed. Islet GIP-R expression and immunohistochemistry studies were performed in pancreas-specific PPARgamma knockout mice (PANC PPARgamma(-/-)), normoglycemic 60% pancreatectomy rats (Px), normoglycemic and hyperglycemic Zucker fatty (ZF) rats, and mouse islets incubated with troglitazone. RESULTS In vitro studies of INS-1 cells confirmed that PPAR-gamma binds to the putative PPRE sequence and regulates GIP-R transcription. In vivo verification was shown by a 70% reduction in GIP-R protein expression in islets from PANC PPARgamma(-/-) mice and a twofold increase in islets of 14-day post-60% Px Sprague-Dawley rats that hyperexpress beta-cell PPARgamma. Thiazolidinedione activation (72 h) of this pathway in normal mouse islets caused a threefold increase of GIP-R protein and a doubling of insulin secretion to 16.7 mmol/l glucose/10 nmol/l GIP. Islets from obese normoglycemic ZF rats had twofold increased PPARgamma and GIP-R protein levels versus lean rats, with both lowered by two-thirds in ZF rats made hyperglycemic by 60% Px. CONCLUSIONS Our studies have shown physiologic and pharmacologic regulation of GIP-R expression in beta-cells by PPARgamma signaling. Also disruption of this signaling pathway may account for the lowered beta-cell GIP-R expression and resulting GIP resistance in type 2 diabetes.
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Affiliation(s)
- Dhananjay Gupta
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont
| | - Mina Peshavaria
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont
| | - Navjot Monga
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont
| | - Thomas L. Jetton
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont
| | - Jack L. Leahy
- From the Division of Endocrinology, Diabetes, and Metabolism and the Department of Medicine, University of Vermont, Burlington, Vermont
- Corresponding author: Jack L. Leahy,
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Mori H, Inoki K, Opland D, Münzberg H, Villanueva EC, Faouzi M, Ikenoue T, Kwiatkowski DJ, Macdougald OA, Myers MG, Guan KL. Critical roles for the TSC-mTOR pathway in β-cell function. Am J Physiol Endocrinol Metab 2009; 297:E1013-22. [PMID: 19690069 PMCID: PMC2781354 DOI: 10.1152/ajpendo.00262.2009] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
TSC1 is a tumor suppressor that associates with TSC2 to inactivate Rheb, thereby inhibiting signaling by the mammalian target of rapamycin (mTOR) complex 1 (mTORC1). mTORC1 stimulates cell growth by promoting anabolic cellular processes, such as translation, in response to growth factors and nutrient signals. To test roles for TSC1 and mTORC1 in β-cell function, we utilized Rip2/Cre to generate mice lacking Tsc1 in pancreatic β-cells (Rip-Tsc1cKO mice). Although obesity developed due to hypothalamic Tsc1 excision in older Rip-Tsc1cKO animals, young animals displayed a prominent gain-of-function β-cell phenotype prior to the onset of obesity. The young Rip-Tsc1cKO animals displayed improved glycemic control due to mTOR-mediated enhancement of β-cell size, mass, and insulin production but not determinants of β-cell number (proliferation and apoptosis), consistent with an important anabolic role for mTOR in β-cell function. Furthermore, mTOR mediated these effects in the face of impaired Akt signaling in β-cells. Thus, mTOR promulgates a dominant signal to promote β-cell/islet size and insulin production, and this pathway is crucial for β-cell function and glycemic control.
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Affiliation(s)
- Hiroyuki Mori
- Dept. of Pharmacology and Moores Cancer Center, Univ. of California San Diego, La Jolla, CA 92093-081, USA.
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