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Kolic J, Sun WG, Cen HH, Ewald JD, Rogalski JC, Sasaki S, Sun H, Rajesh V, Xia YH, Moravcova R, Skovsø S, Spigelman AF, Manning Fox JE, Lyon J, Beet L, Xia J, Lynn FC, Gloyn AL, Foster LJ, MacDonald PE, Johnson JD. Proteomic predictors of individualized nutrient-specific insulin secretion in health and disease. Cell Metab 2024; 36:1619-1633.e5. [PMID: 38959864 PMCID: PMC11250105 DOI: 10.1016/j.cmet.2024.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 02/26/2024] [Accepted: 06/03/2024] [Indexed: 07/05/2024]
Abstract
Population-level variation and mechanisms behind insulin secretion in response to carbohydrate, protein, and fat remain uncharacterized. We defined prototypical insulin secretion responses to three macronutrients in islets from 140 cadaveric donors, including those with type 2 diabetes. The majority of donors' islets exhibited the highest insulin response to glucose, moderate response to amino acid, and minimal response to fatty acid. However, 9% of donors' islets had amino acid responses, and 8% had fatty acid responses that were larger than their glucose-stimulated insulin responses. We leveraged this heterogeneity and used multi-omics to identify molecular correlates of nutrient responsiveness, as well as proteins and mRNAs altered in type 2 diabetes. We also examined nutrient-stimulated insulin release from stem cell-derived islets and observed responsiveness to fat but not carbohydrate or protein-potentially a hallmark of immaturity. Understanding the diversity of insulin responses to carbohydrate, protein, and fat lays the groundwork for personalized nutrition.
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Affiliation(s)
- Jelena Kolic
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.
| | - WenQing Grace Sun
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Haoning Howard Cen
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Jessica D Ewald
- Institute of Parasitology, McGill University, Montreal, QC, Canada
| | - Jason C Rogalski
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Shugo Sasaki
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, BC, Canada; Department of Surgery, School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Han Sun
- Department of Pediatrics, Division of Endocrinology, Stanford School of Medicine, Stanford, CA, USA
| | - Varsha Rajesh
- Department of Pediatrics, Division of Endocrinology, Stanford School of Medicine, Stanford, CA, USA
| | - Yi Han Xia
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Renata Moravcova
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Søs Skovsø
- Valkyrie Life Sciences, Vancouver, BC, Canada
| | - Aliya F Spigelman
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Jocelyn E Manning Fox
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - James Lyon
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Leanne Beet
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Jianguo Xia
- Institute of Parasitology, McGill University, Montreal, QC, Canada
| | - Francis C Lynn
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, BC, Canada; Department of Surgery, School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Anna L Gloyn
- Department of Pediatrics, Division of Endocrinology, Stanford School of Medicine, Stanford, CA, USA; Stanford Diabetes Research Center, Stanford School of Medicine, Stanford, CA, USA; Wellcome Center for Human Genetics, University of Oxford, Oxford, UK
| | - Leonard J Foster
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Patrick E MacDonald
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada; Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - James D Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada; Vancouver Coastal Health Research Institute, Vancouver, BC, Canada.
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Barssotti L, Soares GM, Marconato-Júnior E, Lourençoni Alves B, Oliveira KM, Carneiro EM, Boschero AC, Barbosa HCL. KSRP improves pancreatic beta cell function and survival. Sci Rep 2024; 14:6136. [PMID: 38480757 PMCID: PMC10937633 DOI: 10.1038/s41598-024-55505-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 02/24/2024] [Indexed: 03/17/2024] Open
Abstract
Impaired insulin production and/or secretion by pancreatic beta cells can lead to high blood glucose levels and type 2 diabetes (T2D). Therefore, investigating new proteins involved in beta cell response to stress conditions could be useful in finding new targets for therapeutic approaches. KH-type splicing regulatory protein (KSRP) is a protein usually involved in gene expression due to its role in post-transcriptional regulation. Although there are studies describing the important role of KSRP in tissues closely related to glucose homeostasis, its effect on pancreatic beta cells has not been explored so far. Pancreatic islets from diet-induced obese mice (C57BL/6JUnib) were used to determine KSRP expression and we also performed in vitro experiments exposing INS-1E cells (pancreatic beta cell line) to different stressors (palmitate or cyclopiazonic acid-CPA) to induce cellular dysfunction. Here we show that KSRP expression is reduced in all the beta cell dysfunction models tested. In addition, when manipulated to knock down KSRP, beta cells exhibited increased death and impaired insulin secretion, whereas KSRP overexpression prevented cell death and increased insulin secretion. Taken together, our findings suggest that KSRP could be an important target to protect beta cells from impaired functioning and death.
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Affiliation(s)
- Leticia Barssotti
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil
| | - Gabriela Moreira Soares
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil
| | - Emílio Marconato-Júnior
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil
| | - Bruna Lourençoni Alves
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil
| | - Kênia Moreno Oliveira
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil
| | - Everardo Magalhães Carneiro
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil
| | - Antonio Carlos Boschero
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil
| | - Helena Cristina Lima Barbosa
- Obesity and Comorbidities Research Center (OCRC), Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083864, Brazil.
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Kolic J, Sun WG, Cen HH, Ewald J, Rogalski JC, Sasaki S, Sun H, Rajesh V, Xia YH, Moravcova R, Skovsø S, Spigelman AF, Manning Fox JE, Lyon J, Beet L, Xia J, Lynn FC, Gloyn AL, Foster LJ, MacDonald PE, Johnson JD. Proteomic predictors of individualized nutrient-specific insulin secretion in health and disease. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2023.05.24.23290298. [PMID: 38496562 PMCID: PMC10942505 DOI: 10.1101/2023.05.24.23290298] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Population level variation and molecular mechanisms behind insulin secretion in response to carbohydrate, protein, and fat remain uncharacterized despite ramifications for personalized nutrition. Here, we define prototypical insulin secretion dynamics in response to the three macronutrients in islets from 140 cadaveric donors, including those diagnosed with type 2 diabetes. While islets from the majority of donors exhibited the expected relative response magnitudes, with glucose being highest, amino acid moderate, and fatty acid small, 9% of islets stimulated with amino acid and 8% of islets stimulated with fatty acids had larger responses compared with high glucose. We leveraged this insulin response heterogeneity and used transcriptomics and proteomics to identify molecular correlates of specific nutrient responsiveness, as well as those proteins and mRNAs altered in type 2 diabetes. We also examine nutrient-responsiveness in stem cell-derived islet clusters and observe that they have dysregulated fuel sensitivity, which is a hallmark of functionally immature cells. Our study now represents the first comparison of dynamic responses to nutrients and multi-omics analysis in human insulin secreting cells. Responses of different people's islets to carbohydrate, protein, and fat lay the groundwork for personalized nutrition. ONE-SENTENCE SUMMARY Deep phenotyping and multi-omics reveal individualized nutrient-specific insulin secretion propensity.
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Yuan X, Abdul-Rahman II, Hu S, Li L, He H, Xia L, Hu J, Ran M, Liu Y, Abdulai M, Wang J. Mechanism of SCD Participation in Lipid Droplet-Mediated Steroidogenesis in Goose Granulosa Cells. Genes (Basel) 2022; 13:genes13091516. [PMID: 36140684 PMCID: PMC9498882 DOI: 10.3390/genes13091516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 11/16/2022] Open
Abstract
Stearoyl-CoA desaturase (SCD) is a key enzyme catalyzing the rate-limiting step in monounsaturated fatty acids (MUFAs) production. There may be a mechanism by which SCD is involved in lipid metabolism, which is assumed to be essential for goose follicular development. For this reason, a cellular model of SCD function in goose granulosa cells (GCs) via SCD overexpression and knockdown was used to determine the role of SCD in GC proliferation using flow cytometry. We found that SCD overexpression induced and SCD knockdown inhibited GCs proliferation. Furthermore, ELISA analysis showed that SCD overexpression increased the total cholesterol (TC), progesterone, and estrogen levels in GCs, while SCD knockdown decreased TC, progesterone, and estrogen levels (p < 0.05). Combining these results with those of related multi-omics reports, we proposed a mechanism of SCD regulating the key lipids and differentially expressed gene (DEGs) in glycerophospholipid and glycerolipid metabolism, which participate in steroidogenesis mediated by the lipid droplet deposition in goose GCs. These results add further insights into understanding the lipid metabolism mechanism of goose GCs.
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Affiliation(s)
- Xin Yuan
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Ibn Iddriss Abdul-Rahman
- Department of Veterinary Science, Faculty of Agriculture, University for Development Studies, Nyankpala Campus, Tamale P.O. Box TL 1882, Ghana
| | - Shenqiang Hu
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Liang Li
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Hua He
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Lu Xia
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Jiwei Hu
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Mingxia Ran
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Yali Liu
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Mariama Abdulai
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
| | - Jiwen Wang
- Country Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China
- Correspondence: ; Tel.: +86-028-8629-098
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Pathophysiology of Lipid Droplets in Neuroglia. Antioxidants (Basel) 2021; 11:antiox11010022. [PMID: 35052526 PMCID: PMC8773017 DOI: 10.3390/antiox11010022] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 12/12/2022] Open
Abstract
In recent years, increasing evidence regarding the functional importance of lipid droplets (LDs), cytoplasmic storage organelles in the central nervous system (CNS), has emerged. Although not abundantly present in the CNS under normal conditions in adulthood, LDs accumulate in the CNS during development and aging, as well as in some neurologic disorders. LDs are actively involved in cellular lipid turnover and stress response. By regulating the storage of excess fatty acids, cholesterol, and ceramides in addition to their subsequent release in response to cell needs and/or environmental stressors, LDs are involved in energy production, in the synthesis of membranes and signaling molecules, and in the protection of cells against lipotoxicity and free radicals. Accumulation of LDs in the CNS appears predominantly in neuroglia (astrocytes, microglia, oligodendrocytes, ependymal cells), which provide trophic, metabolic, and immune support to neuronal networks. Here we review the most recent findings on the characteristics and functions of LDs in neuroglia, focusing on astrocytes, the key homeostasis-providing cells in the CNS. We discuss the molecular mechanisms affecting LD turnover in neuroglia under stress and how this may protect neural cell function. We also highlight the role (and potential contribution) of neuroglial LDs in aging and in neurologic disorders.
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Bazydlo-Guzenda K, Buda P, Mach M, Pieczykolan J, Kozlowska I, Janiszewski M, Drzazga E, Dominowski J, Ziolkowski H, Wieczorek M, Gad SC. Evaluation of the hepatotoxicity of the novel GPR40 (FFAR1) agonist CPL207280 in the rat and monkey. PLoS One 2021; 16:e0257477. [PMID: 34555055 PMCID: PMC8459971 DOI: 10.1371/journal.pone.0257477] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/01/2021] [Indexed: 12/13/2022] Open
Abstract
GPR40 (FFAR1) is a promising target for the managing type 2 diabetes (T2D). The most advanced GPR40 agonist TAK-875 exhibited satisfactory glucose-lowering effects in phase II and III studies. However, the phase III studies of TAK-875 revealed drug-induced liver injury (DILI). It is unknown whether DILI is a consequence of a specific GPR40 agonist or is an inherent feature of all GPR40 agonists. CPL207280 is a novel GPR40 agonist that improves diabetes in Zucker Diabetic Fatty (ZDF) rats, Goto Kakizaki (GK) rats and db/db mice. In this report, the DILI-related toxicity of CPL207280 was compared directly with that of TAK-875. In vitro studies evaluating hepatic biliary transporter inhibition, mitochondrial function, and metabolic profiling were performed in hepatocytes from different species. The long term toxicity of CPL207280 was studied in vivo in rats and monkeys. Activity of CPL207280 was one order of magnitude lesser than that of TAK-875 for the inhibition of bile acid transporters. CPL207280 had a negligible effect on the hepatic mitochondria. In contrast to TAK-875, which was metabolized through toxic glucuronidation, CPL207280 was metabolized mainly through oxidation. No deleterious hepatic effects were observed in chronically treated healthy and diabetic animals. The study presents promising data on the feasibility of creating a liver-safe GPR40 agonist. Additionally, it can be concluded that DILI is not a hallmark of GPR40 agonists; it is linked to the intrinsic properties of an individual agonist.
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Affiliation(s)
- Katarzyna Bazydlo-Guzenda
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
- Postgraduate School of Molecular Medicine, Warsaw, Poland
| | - Pawel Buda
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
| | - Mateusz Mach
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
| | - Jerzy Pieczykolan
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
| | - Izabela Kozlowska
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
| | | | - Ewa Drzazga
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
| | - Jakub Dominowski
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
| | - Hubert Ziolkowski
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Warmia and Mazury, Olsztyn, Poland
| | - Maciej Wieczorek
- Innovative Drugs R&D Department, Celon Pharma S.A., Lomianki, Poland
| | - Shayne Cox Gad
- Gad Consulting Services, Raleigh, North Carolina Area, United States of America
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Desmet KLJ, Marei WFA, Richard C, Sprangers K, Beemster GTS, Meysman P, Laukens K, Declerck K, Vanden Berghe W, Bols PEJ, Hue I, Leroy JLMR. Oocyte maturation under lipotoxic conditions induces carryover transcriptomic and functional alterations during post-hatching development of good-quality blastocysts: novel insights from a bovine embryo-transfer model. Hum Reprod 2021; 35:293-307. [PMID: 32112081 DOI: 10.1093/humrep/dez248] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 10/09/2019] [Indexed: 12/24/2022] Open
Abstract
STUDY QUESTION Does oocyte maturation under lipolytic conditions have detrimental carry-over effects on post-hatching embryo development of good-quality blastocysts after transfer? SUMMARY ANSWER Surviving, morphologically normal blastocysts derived from bovine oocytes that matured under lipotoxic conditions exhibit long-lasting cellular dysfunction at the transcriptomic and metabolic levels, which coincides with retarded post-hatching embryo development. WHAT IS KNOWN ALREADY There is increasing evidence showing that following maturation in pathophysiologically relevant lipotoxic conditions (as in obesity or metabolic syndrome), surviving blastocysts of good (transferable) morphological quality have persistent transcriptomic and epigenetic alteration even when in vitro embryo culture takes place under standard conditions. However, very little is known about subsequent development in the uterus after transfer. STUDY DESIGN, SIZE, DURATION Bovine oocytes were matured in vitro in the presence of pathophysiologically relevant, high non-esterified fatty acid (NEFA) concentrations (HIGH PA), or in basal NEFA concentrations (BASAL) as a physiological control. Eight healthy multiparous non-lactating Holstein cows were used for embryo transfers. Good-quality blastocysts (pools of eight) were transferred per cow, and cows were crossed over for treatments in the next replicate. Embryos were recovered 7 days later and assessed for post-hatching development, phenotypic features and gene expression profile. Blastocysts from solvent-free and NEFA-free maturation (CONTROL) were also tested for comparison. PARTICIPANTS/MATERIALS, SETTING, METHODS Recovered Day 14 embryos were morphologically assessed and dissected into embryonic disk (ED) and extraembryonic tissue (EXT). Samples of EXT were cultured for 24 h to assess cellular metabolic activity (glucose and pyruvate consumption and lactate production) and embryos' ability to signal for maternal recognition of pregnancy (interferon-τ secretion; IFN-τ). ED and EXT samples were subjected to RNA sequencing to evaluate the genome-wide transcriptome patterns. MAIN RESULTS AND THE ROLE OF CHANCE The embryo recovery rate at Day 14 p.i. was not significantly different among treatment groups (P > 0.1). However, higher proportions of HIGH PA embryos were retarded in growth (in spherical stage) compared to the more elongated tubular stage embryos in the BASAL group (P < 0.05). Focusing on the normally developed tubular embryos in both groups, HIGH PA exposure resulted in altered cellular metabolism and altered transcriptome profile particularly in pathways related to redox-regulating mechanisms, apoptosis, cellular growth, interaction and differentiation, energy metabolism and epigenetic mechanisms, compared to BASAL embryos. Maturation under BASAL conditions did not have any significant effects on post-hatching development and cellular functions compared to CONTROL. LARGE-SCALE DATA The datasets of RNA sequencing analysis are available in the NCBI's Gene Expression Omnibus (GEO) repository, series accession number GSE127889 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE127889). Datasets of differentially expressed genes and their gene ontology functions are available in the Mendeley datasets at http://dx.doi.org/10.17632/my2z7dvk9j.2. LIMITATIONS, REASONS FOR CAUTION The bovine model was used here to allow non-invasive embryo transfer and post-hatching recovery on Day 14. There are physiological differences in some characteristics of post-hatching embryo development between human and cows, such as embryo elongation and trophoblastic invasion. However, the main carry-over effects of oocyte maturation under lipolytic conditions described here are evident at the cellular level and therefore may also occur during post-hatching development in other species including humans. In addition, post-hatching development was studied here under a healthy uterine environment to focus on carry-over effects originating from the oocyte, whereas additional detrimental effects may be induced by maternal metabolic disorders due to adverse changes in the uterine microenvironment. RNA sequencing results were not verified by qPCR, and no solvent control was included. WIDER IMPLICATIONS OF THE FINDINGS Our observations may increase the awareness of the importance of maternal metabolic stress at the level of the preovulatory oocyte in relation to carry-over effects that may persist in the transferrable embryos. It should further stimulate new research about preventive and protective strategies to optimize maternal metabolic health around conception to maximize embryo viability and thus fertility outcome. STUDY FUNDING/COMPETING INTEREST(S) This study was supported by the Flemish Research Fund (FWO grant 11L8716N and FWO project 42/FAO10300/6541). The authors declare there are no conflicts of interest.
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Affiliation(s)
- Karolien L J Desmet
- Laboratory of Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium
| | - Waleed F A Marei
- Laboratory of Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium.,Department of Theriogenology, Faculty of Veterinary Medicine, Cairo University, 12211 Giza, Egypt
| | - Christophe Richard
- UMR Biologie du Développement et Reproduction, Institut National de la Recherche Agronomique (INRA), École Nationale Vétérinaire d'Alford, Université Paris-Saclay, 78352 Jouy-en-Josas, France
| | - Katrien Sprangers
- Integrated Molecular Plant Physiology Research Group (IMPRES), Department of Biology, University of Antwerp, 2020 Antwerp, Belgium
| | - Gerrit T S Beemster
- Integrated Molecular Plant Physiology Research Group (IMPRES), Department of Biology, University of Antwerp, 2020 Antwerp, Belgium
| | - Pieter Meysman
- Biomedical Informatics Research Center Antwerp, Department of Mathematics and Computer Science, University of Antwerp, 2610 Wilrijk, Belgium
| | - Kris Laukens
- Biomedical Informatics Research Center Antwerp, Department of Mathematics and Computer Science, University of Antwerp, 2610 Wilrijk, Belgium
| | - Ken Declerck
- Laboratory of Protein Science, Proteomics and Epigenetic Signaling, Department of Biomedical Sciences, University of Antwerp, 2610 Wilrijk, Belgium
| | - Wim Vanden Berghe
- Laboratory of Protein Science, Proteomics and Epigenetic Signaling, Department of Biomedical Sciences, University of Antwerp, 2610 Wilrijk, Belgium
| | - Peter E J Bols
- Laboratory of Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium
| | - Isabelle Hue
- UMR Biologie du Développement et Reproduction, Institut National de la Recherche Agronomique (INRA), École Nationale Vétérinaire d'Alford, Université Paris-Saclay, 78352 Jouy-en-Josas, France
| | - Jo L M R Leroy
- Laboratory of Veterinary Physiology and Biochemistry, Department of Veterinary Sciences, University of Antwerp, 2610 Wilrijk, Belgium
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Šrámek J, Němcová-Fürstová V, Kovář J. Molecular Mechanisms of Apoptosis Induction and Its Regulation by Fatty Acids in Pancreatic β-Cells. Int J Mol Sci 2021; 22:4285. [PMID: 33924206 PMCID: PMC8074590 DOI: 10.3390/ijms22084285] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/09/2021] [Accepted: 04/16/2021] [Indexed: 02/06/2023] Open
Abstract
Pancreatic β-cell failure and death contribute significantly to the pathogenesis of type 2 diabetes. One of the main factors responsible for β-cell dysfunction and subsequent cell death is chronic exposure to increased concentrations of FAs (fatty acids). The effect of FAs seems to depend particularly on the degree of their saturation. Saturated FAs induce apoptosis in pancreatic β-cells, whereas unsaturated FAs are well tolerated and are even capable of inhibiting the pro-apoptotic effect of saturated FAs. Molecular mechanisms of apoptosis induction by saturated FAs in β-cells are not completely elucidated. Saturated FAs induce ER stress, which in turn leads to activation of all ER stress pathways. When ER stress is severe or prolonged, apoptosis is induced. The main mediator seems to be the CHOP transcription factor. Via regulation of expression/activity of pro- and anti-apoptotic Bcl-2 family members, and potentially also through the increase in ROS production, CHOP switches on the mitochondrial pathway of apoptosis induction. ER stress signalling also possibly leads to autophagy signalling, which may activate caspase-8. Saturated FAs activate or inhibit various signalling pathways, i.e., p38 MAPK signalling, ERK signalling, ceramide signalling, Akt signalling and PKCδ signalling. This may lead to the activation of the mitochondrial pathway of apoptosis, as well. Particularly, the inhibition of the pro-survival Akt signalling seems to play an important role. This inhibition may be mediated by multiple pathways (e.g., ER stress signalling, PKCδ and ceramide) and could also consequence in autophagy signalling. Experimental evidence indicates the involvement of certain miRNAs in mechanisms of FA-induced β-cell apoptosis, as well. In the rather rare situations when unsaturated FAs are also shown to be pro-apoptotic, the mechanisms mediating this effect in β-cells seem to be the same as for saturated FAs. To conclude, FA-induced apoptosis rather appears to be preceded by complex cross talks of multiple signalling pathways. Some of these pathways may be regulated by decreased membrane fluidity due to saturated FA incorporation. Few data are available concerning molecular mechanisms mediating the protective effect of unsaturated FAs on the effect of saturated FAs. It seems that the main possible mechanism represents a rather inhibitory intervention into saturated FA-induced pro-apoptotic signalling than activation of some pro-survival signalling pathway(s) or metabolic interference in β-cells. This inhibitory intervention may be due to an increase of membrane fluidity.
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Affiliation(s)
- Jan Šrámek
- Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague, Czech Republic;
| | - Vlasta Němcová-Fürstová
- Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague, Czech Republic;
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9
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Exogenous Fatty Acids Modulate ER Lipid Composition and Metabolism in Breast Cancer Cells. Cells 2021; 10:cells10010175. [PMID: 33467111 PMCID: PMC7830208 DOI: 10.3390/cells10010175] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 02/06/2023] Open
Abstract
(1) Background: Lipid metabolism is a fundamental hallmark of all tumors, especially of breast cancer. Few studies describe the different lipid metabolisms and sensitivities to the microenvironment of breast cancer cell subtypes that influence the proliferation, aggressiveness, and success of therapy. This study describes the impact of lipid microenvironment on endoplasmic reticulum (ER) membrane and metabolic activity in two breast cancer cell lines with Luminal A and triple-negative breast cancer (TNBC) features. (2) Methods: We investigated the peculiar lipid phenotype of a TNBC cell line, MDA-MB-231, and a Luminal A cell line, MCF7, and their different sensitivity to exogenous fatty acids (i.e., palmitic acid (PA) and docosahexaenoic acid (DHA)). Moreover, we verified the impact of exogenous fatty acids on ER lipid composition. (3) Results: The data obtained demonstrate that MDA-MB-231 cells are more sensitive to the lipid microenvironment and that both PA and DHA are able to remodel their ER membranes with consequences on resident enzyme activity. On the contrary, MCF7 cells are less sensitive to PA, whereas they incorporate DHA, although less efficiently than MDA-MB-231 cells. (4) Conclusions: This study sustains the importance of lipid metabolism as an innovative hallmark to discriminate breast cancer subclasses and to develop personalized and innovative pharmacological strategies. The different sensitivities to the lipid environment shown by MCF7 and MDA-MB-231 cells might be related to cell malignancy and chemoresistance onset. In the future, this new approach could lead to a substantial decrease both in deleterious side effects for the patients and in the cost of entire therapeutic treatments coupled with increased therapy efficiency.
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10
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Engin AB, Engin A. Protein Kinases Signaling in Pancreatic Beta-cells Death and Type 2 Diabetes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1275:195-227. [PMID: 33539017 DOI: 10.1007/978-3-030-49844-3_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Type 2 diabetes (T2D) is a worldwide serious public health problem. Insulin resistance and β-cell failure are the two major components of T2D pathology. In addition to defective endoplasmic reticulum (ER) stress signaling due to glucolipotoxicity, β-cell dysfunction or β-cell death initiates the deleterious vicious cycle observed in T2D. Although the primary cause is still unknown, overnutrition that contributes to the induction of the state of low-grade inflammation, and the activation of various protein kinases-related metabolic pathways are main factors leading to T2D. In this chapter following subjects, which have critical checkpoints regarding β-cell fate and protein kinases pathways are discussed; hyperglycemia-induced β-cell failure, chronic accumulation of unfolded protein in β-cells, the effect of intracellular reactive oxygen species (ROS) signaling to insulin secretion, excessive saturated free fatty acid-induced β-cell apoptosis, mitophagy dysfunction, proinflammatory responses and insulin resistance, and the reprogramming of β-cell for differentiation or dedifferentiation in T2D. There is much debate about selecting proposed therapeutic strategies to maintain or enhance optimal β-cell viability for adequate insulin secretion in T2D. However, in order to achieve an effective solution in the treatment of T2D, more intensive clinical trials are required on newer therapeutic options based on protein kinases signaling pathways.
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Affiliation(s)
- Ayse Basak Engin
- Department of Toxicology, Faculty of Pharmacy, Gazi University, Ankara, Turkey.
| | - Atilla Engin
- Department of General Surgery, Faculty of Medicine, Gazi University, Ankara, Turkey
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11
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Vilas-Boas EA, Nalbach L, Ampofo E, Lucena CF, Naudet L, Ortis F, Carpinelli AR, Morgan B, Roma LP. Transient NADPH oxidase 2-dependent H 2O 2 production drives early palmitate-induced lipotoxicity in pancreatic islets. Free Radic Biol Med 2021; 162:1-13. [PMID: 33249137 DOI: 10.1016/j.freeradbiomed.2020.11.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 01/12/2023]
Abstract
Modern lifestyles, including lack of physical activity and poor nutritional habits, are driving the rapidly increasing prevalence of obesity and type 2 diabetes. Increased levels of free fatty acids (FFAs), particularly saturated FFAs, in obese individuals have been linked to pancreatic β-cell failure. This process, termed lipotoxicity, involves activation of several stress responses, including ER stress and oxidative stress. However, the molecular underpinnings and causal relationships between the disparate stress responses remain unclear. Here we employed transgenic mice, expressing a genetically-encoded cytosolic H2O2 sensor, roGFP2-Orp1, to monitor dynamic changes in H2O2 levels in pancreatic islets in response to chronic palmitate exposure. We identified a transient increase in H2O2 levels from 4 to 8 h after palmitate addition, which was mirrored by a concomitant decrease in cellular NAD(P)H levels. Intriguingly, islets isolated from NOX2 knock-out mice displayed no H2O2 transient upon chronic palmitate treatment. Furthermore, NOX2 knockout rescued palmitate-dependent impairment of insulin secretion, calcium homeostasis and viability. Chemical inhibition of NOX activity protected islets from palmitate-induced impairment in insulin secretion, however had no detectable impact upon the induction of ER stress. In summary, our results reveal that transient NOX2-dependent H2O2 production is a likely cause of early palmitate-dependent lipotoxic effects.
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Affiliation(s)
- Eloisa Aparecida Vilas-Boas
- Department of Biophysics, Center for Human and Molecular Biology (ZHMB), Saarland University, Homburg, Germany; Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Lisa Nalbach
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Emmanuel Ampofo
- Institute for Clinical and Experimental Surgery, Saarland University, Homburg, Germany
| | - Camila Ferraz Lucena
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Léa Naudet
- Department of Biophysics, Center for Human and Molecular Biology (ZHMB), Saarland University, Homburg, Germany
| | - Fernanda Ortis
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Bruce Morgan
- Institute for Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, Saarbrücken, Germany
| | - Leticia Prates Roma
- Department of Biophysics, Center for Human and Molecular Biology (ZHMB), Saarland University, Homburg, Germany.
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12
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Zhao T, Ma J, Li L, Teng W, Tian Y, Ma Y, Wang W, Yan W, Jiao P. MKP-5 Relieves Lipotoxicity-Induced Islet β-Cell Dysfunction and Apoptosis via Regulation of Autophagy. Int J Mol Sci 2020; 21:ijms21197161. [PMID: 32998359 PMCID: PMC7582937 DOI: 10.3390/ijms21197161] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 09/16/2020] [Accepted: 09/25/2020] [Indexed: 01/28/2023] Open
Abstract
Mitogen-activated protein kinase phosphatase-5 (MKP-5) is a regulator of extracellular signaling that is known to regulate lipid metabolism. In this study, we found that obesity caused by a high-fat diet (HFD) decreased the expression of MKP-5 in the pancreas and primary islet cells derived from mice. Then, we further investigated the role of MKP-5 in the protection of islet cells from lipotoxicity by modulating MKP-5 expression. As a critical inducer of lipotoxicity, palmitic acid (PA) was used to treat islet β-cells. We found that MKP-5 overexpression restored PA-mediated autophagy inhibition in Rin-m5f cells and protected these cells from PA-induced apoptosis and dysfunction. Consistently, a lack of MKP-5 aggravated the adverse effects of lipotoxicity. Islet cells from HFD-fed mice were infected using recombinant adenovirus expressing MKP-5 (Ad-MKP-5), and we found that Ad-MKP-5 was able to alleviate HFD-induced apoptotic protein activation and relieve the HFD-mediated inhibition of functional proteins. Notably, HFD-mediated impairments in autophagic flux were restored by Ad-MKP-5 transduction. Furthermore, the autophagy inhibitor 3-methyladenine (3-MA) was used to treat Rin-m5f cells, confirming that the MKP-5 overexpression suppressed apoptosis, dysfunction, inflammatory response, and oxidative stress induced by PA via improving autophagic signaling. Lastly, employing c-Jun amino-terminal kinas (JNK), P38, or extracellular-regulated kinase (ERK) inhibitors, we established that the JNK and P38 MAPK pathways were involved in the MKP-5-mediated apoptosis, dysfunction, and autophagic inhibition observed in islet β cells in response to lipotoxicity.
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Affiliation(s)
| | | | | | | | | | | | | | - Weiqun Yan
- Correspondence: (W.Y.); (P.J.); Tel.: +86-431-8561-9289 (P.J.)
| | - Ping Jiao
- Correspondence: (W.Y.); (P.J.); Tel.: +86-431-8561-9289 (P.J.)
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13
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Sarnyai F, Somogyi A, Gór-Nagy Z, Zámbó V, Szelényi P, Mátyási J, Simon-Szabó L, Kereszturi É, Tóth B, Csala M. Effect of cis- and trans-Monounsaturated Fatty Acids on Palmitate Toxicity and on Palmitate-induced Accumulation of Ceramides and Diglycerides. Int J Mol Sci 2020; 21:ijms21072626. [PMID: 32283839 PMCID: PMC7178055 DOI: 10.3390/ijms21072626] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/02/2020] [Accepted: 04/07/2020] [Indexed: 01/22/2023] Open
Abstract
Dietary trans fatty acids (TFAs) have been implicated in serious health risks, yet little is known about their cellular effects and metabolism. We aim to undertake an in vitro comparison of two representative TFAs (elaidate and vaccenate) to the best-characterized endogenous cis-unsaturated FA (oleate). The present study addresses the possible protective action of TFAs on palmitate-treated RINm5F insulinoma cells with special regards to apoptosis, endoplasmic reticulum stress and the underlying ceramide and diglyceride (DG) accumulation. Both TFAs significantly improved cell viability and reduced apoptosis in palmitate-treated cells. They mildly attenuated palmitate-induced XBP-1 mRNA cleavage and phosphorylation of eukaryotic initiation factor 2α (eIF2α) and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), but they were markedly less potent than oleate. Accordingly, all the three unsaturated FAs markedly reduced cellular palmitate incorporation and prevented harmful ceramide and DG accumulation. However, more elaidate or vaccenate than oleate was inserted into ceramides and DGs. Our results revealed a protective effect of TFAs in short-term palmitate toxicity, yet they also provide important in vitro evidence and even a potential mechanism for unfavorable long-term health effects of TFAs compared to oleate.
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Affiliation(s)
- Farkas Sarnyai
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, H-1085 Budapest, Hungary
| | - Anna Somogyi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, H-1085 Budapest, Hungary
| | - Zsófia Gór-Nagy
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1111 Budapest, Hungary
| | - Veronika Zámbó
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, H-1085 Budapest, Hungary
| | - Péter Szelényi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, H-1085 Budapest, Hungary
| | - Judit Mátyási
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1111 Budapest, Hungary
| | - Laura Simon-Szabó
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, H-1085 Budapest, Hungary
| | - Éva Kereszturi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, H-1085 Budapest, Hungary
| | - Blanka Tóth
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1111 Budapest, Hungary
- Correspondence: (B.T.); (M.C.)
| | - Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, H-1085 Budapest, Hungary
- Correspondence: (B.T.); (M.C.)
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14
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Vilas-Boas EA, Karabacz N, Marsiglio-Librais GN, Valle MMR, Nalbach L, Ampofo E, Morgan B, Carpinelli AR, Roma LP. Chronic activation of GPR40 does not negatively impact upon BRIN-BD11 pancreatic β-cell physiology and function. Pharmacol Rep 2020; 72:1725-1737. [PMID: 32274767 PMCID: PMC7704488 DOI: 10.1007/s43440-020-00101-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/18/2020] [Accepted: 03/21/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Free fatty acids (FFAs) are known for their dual effects on insulin secretion and pancreatic β-cell survival. Short-term exposure to FFAs, such as palmitate, increases insulin secretion. On the contrary, long-term exposure to saturated FFAs results in decreased insulin secretion, as well as triggering oxidative stress and endoplasmic reticulum (ER) stress, culminating in cell death. The effects of FFAs can be mediated either via their intracellular oxidation and consequent effects on cellular metabolism or via activation of the membrane receptor GPR40. Both pathways are likely to be activated upon both short- and long-term exposure to FFAs. However, the precise role of GPR40 in β-cell physiology, especially upon chronic exposure to FFAs, remains unclear. METHODS We used the GPR40 agonist (GW9508) and antagonist (GW1100) to investigate the impact of chronically modulating GPR40 activity on BRIN-BD11 pancreatic β-cells physiology and function. RESULTS We observed that chronic activation of GPR40 did not lead to increased apoptosis, and both proliferation and glucose-induced calcium entry were unchanged compared to control conditions. We also observed no increase in H2O2 or superoxide levels and no increase in the ER stress markers p-eIF2α, CHOP and BIP. As expected, palmitate led to increased H2O2 levels, decreased cell viability and proliferation, as well as decreased metabolism and calcium entry. These changes were not counteracted by the co-treatment of palmitate-exposed cells with the GPR40 antagonist GW1100. CONCLUSIONS Chronic activation of GPR40 using GW9508 does not negatively impact upon BRIN-BD11 pancreatic β-cells physiology and function. The GPR40 antagonist GW1100 does not protect against the deleterious effects of chronic palmitate exposure. We conclude that GPR40 is probably not involved in mediating the toxicity associated with chronic palmitate exposure.
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Affiliation(s)
- Eloisa Aparecida Vilas-Boas
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo (USP), Sao Paulo, SP, Brazil.,Department of Biophysics, Center for Human and Molecular Biology, Saarland University, Universität Des Saarlandes, CIPMM, Geb. 48, 66421, Homburg/Saar, Germany
| | - Noémie Karabacz
- Department of Biophysics, Center for Human and Molecular Biology, Saarland University, Universität Des Saarlandes, CIPMM, Geb. 48, 66421, Homburg/Saar, Germany
| | | | - Maíra Melo Rezende Valle
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo (USP), Sao Paulo, SP, Brazil
| | - Lisa Nalbach
- Institute for Clinical and Experimental Surgery, Saarland University, 66421, Homburg/Saar, Germany
| | - Emmanuel Ampofo
- Institute for Clinical and Experimental Surgery, Saarland University, 66421, Homburg/Saar, Germany
| | - Bruce Morgan
- Institute of Biochemistry, Center for Human and Molecular Biology (ZHMB), Saarland University, 66123, Saarbrücken, Germany
| | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo (USP), Sao Paulo, SP, Brazil
| | - Leticia Prates Roma
- Department of Biophysics, Center for Human and Molecular Biology, Saarland University, Universität Des Saarlandes, CIPMM, Geb. 48, 66421, Homburg/Saar, Germany.
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15
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Carter SD, Hampton CM, Langlois R, Melero R, Farino ZJ, Calderon MJ, Li W, Wallace CT, Tran NH, Grassucci RA, Siegmund SE, Pemberton J, Morgenstern TJ, Eisenman L, Aguilar JI, Greenberg NL, Levy ES, Yi E, Mitchell WG, Rice WJ, Wigge C, Pilli J, George EW, Aslanoglou D, Courel M, Freyberg RJ, Javitch JA, Wills ZP, Area-Gomez E, Shiva S, Bartolini F, Volchuk A, Murray SA, Aridor M, Fish KN, Walter P, Balla T, Fass D, Wolf SG, Watkins SC, Carazo JM, Jensen GJ, Frank J, Freyberg Z. Ribosome-associated vesicles: A dynamic subcompartment of the endoplasmic reticulum in secretory cells. SCIENCE ADVANCES 2020; 6:eaay9572. [PMID: 32270040 PMCID: PMC7112762 DOI: 10.1126/sciadv.aay9572] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 01/13/2020] [Indexed: 05/21/2023]
Abstract
The endoplasmic reticulum (ER) is a highly dynamic network of membranes. Here, we combine live-cell microscopy with in situ cryo-electron tomography to directly visualize ER dynamics in several secretory cell types including pancreatic β-cells and neurons under near-native conditions. Using these imaging approaches, we identify a novel, mobile form of ER, ribosome-associated vesicles (RAVs), found primarily in the cell periphery, which is conserved across different cell types and species. We show that RAVs exist as distinct, highly dynamic structures separate from the intact ER reticular architecture that interact with mitochondria via direct intermembrane contacts. These findings describe a new ER subcompartment within cells.
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Affiliation(s)
- Stephen D. Carter
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Cheri M. Hampton
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Robert Langlois
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Roberto Melero
- Biocomputing Unit, Centro Nacional de Biotecnología–CSIC, Darwin 3, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Zachary J. Farino
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Michael J. Calderon
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Wen Li
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Callen T. Wallace
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Ngoc Han Tran
- HHMI, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Robert A. Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Stephanie E. Siegmund
- Department of Cellular, Molecular and Biophysical Studies, Columbia University Medical Center, New York, NY 10032, USA
- Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Joshua Pemberton
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Travis J. Morgenstern
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Leanna Eisenman
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jenny I. Aguilar
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Nili L. Greenberg
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Elana S. Levy
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Edward Yi
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - William G. Mitchell
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | | | | | - Jyotsna Pilli
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Emily W. George
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Despoina Aslanoglou
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Maïté Courel
- CNRS-UMR7622, Institut de Biologie Paris-Seine, Université Pierre & Marie Curie, 75252 Paris, France
| | - Robin J. Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jonathan A. Javitch
- Department of Psychiatry, Columbia University, New York, NY 10032, USA
- Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, USA
| | - Zachary P. Wills
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Estela Area-Gomez
- Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Sruti Shiva
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Francesca Bartolini
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Allen Volchuk
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Sandra A. Murray
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Meir Aridor
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Kenneth N. Fish
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Peter Walter
- HHMI, Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Sharon G. Wolf
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, Israel
| | - Simon C. Watkins
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - José María Carazo
- Biocomputing Unit, Centro Nacional de Biotecnología–CSIC, Darwin 3, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Grant J. Jensen
- HHMI, Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Zachary Freyberg
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
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16
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Gordaliza‐Alaguero I, Cantó C, Zorzano A. Metabolic implications of organelle-mitochondria communication. EMBO Rep 2019; 20:e47928. [PMID: 31418169 PMCID: PMC6726909 DOI: 10.15252/embr.201947928] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/10/2019] [Accepted: 05/28/2019] [Indexed: 12/31/2022] Open
Abstract
Cellular organelles are not static but show dynamism-a property that is likely relevant for their function. In addition, they interact with other organelles in a highly dynamic manner. In this review, we analyze the proteins involved in the interaction between mitochondria and other cellular organelles, especially the endoplasmic reticulum, lipid droplets, and lysosomes. Recent results indicate that, on one hand, metabolic alterations perturb the interaction between mitochondria and other organelles, and, on the other hand, that deficiency in proteins involved in the tethering between mitochondria and the ER or in specific functions of the interaction leads to metabolic alterations in a variety of tissues. The interaction between organelles is an emerging field that will permit to identify key proteins, to delineate novel modulation pathways, and to elucidate their implications in human disease.
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Affiliation(s)
- Isabel Gordaliza‐Alaguero
- Institute for Research in Biomedicine (IRB Barcelona)Barcelona Institute of Science and Technology (BIST)BarcelonaSpain
- CIBER de Diabetes y Enfermedades Metabolicas AsociadasBarcelonaSpain
- Departamento de Bioquimica i Biomedicina MolecularFacultat de BiologiaUniversitat de BarcelonaBarcelonaSpain
| | - Carlos Cantó
- Nestle Institute of Health Sciences (NIHS)LausanneSwitzerland
- School of Life SciencesEcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona)Barcelona Institute of Science and Technology (BIST)BarcelonaSpain
- CIBER de Diabetes y Enfermedades Metabolicas AsociadasBarcelonaSpain
- Departamento de Bioquimica i Biomedicina MolecularFacultat de BiologiaUniversitat de BarcelonaBarcelonaSpain
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17
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Hao Y, Shen S, Yin F, Zhang Y, Liu J. Unfolded protein response is involved in geniposide‐regulating glucose‐stimulated insulin secretion in INS‐1 cells. Cell Biochem Funct 2019; 37:368-376. [DOI: 10.1002/cbf.3414] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 05/06/2019] [Indexed: 02/04/2023]
Affiliation(s)
- Yanan Hao
- Chongqing Key Laboratory of Medicinal Chemistry and Molecular PharmacologyChongqing University of Technology Chongqing China
| | - Shenli Shen
- Chongqing Key Laboratory of Medicinal Chemistry and Molecular PharmacologyChongqing University of Technology Chongqing China
| | - Fei Yin
- Chongqing Key Laboratory of Medicinal Chemistry and Molecular PharmacologyChongqing University of Technology Chongqing China
| | - Yonglan Zhang
- Chongqing Key Laboratory of Medicinal Chemistry and Molecular PharmacologyChongqing University of Technology Chongqing China
| | - Jianhui Liu
- Chongqing Key Laboratory of Medicinal Chemistry and Molecular PharmacologyChongqing University of Technology Chongqing China
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18
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Majumder P, Roy K, Bagh S, Mukhopadhyay D. Receptor tyrosine kinases (RTKs) consociate in regulatory clusters in Alzheimer's disease and type 2 diabetes. Mol Cell Biochem 2019; 459:171-182. [PMID: 31154588 DOI: 10.1007/s11010-019-03560-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 05/27/2019] [Indexed: 01/09/2023]
Abstract
Alzheimer's disease (AD) and type 2 diabetes (T2D) share the common hallmark of insulin resistance. It is conjectured that receptor tyrosine kinases (RTKs) play definitive roles in the process. To decipher the signaling overlap behind this phenotypic resemblance, the activity status of RTKs is probed in post-mortem AD and T2D tissues and cell models. Activities of only about one-third changed in a similar fashion, whereas about half of them showed opposite outcomes when exposed to contrasting signals akin to AD and T2D. Interestingly, irrespective of disease type, RTKs with enhanced and compromised activities clustered distinctly, indicating separate levels of regulations. Similar regulatory mechanisms within an activity cluster could be inferred, which have potential to impact future therapeutic developments.
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Affiliation(s)
- Piyali Majumder
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, HBNI, Block-AF, Sector-1, Bidhannagar, Kolkata, WB, 700064, India
| | - Kasturi Roy
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, HBNI, Block-AF, Sector-1, Bidhannagar, Kolkata, WB, 700064, India
| | - Sangram Bagh
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, HBNI, Block-AF, Sector-1, Bidhannagar, Kolkata, WB, 700064, India
| | - Debashis Mukhopadhyay
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, HBNI, Block-AF, Sector-1, Bidhannagar, Kolkata, WB, 700064, India.
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19
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Shahrestanaki MK, Arasi FP, Aghaei M. Adenosine protects pancreatic beta cells against apoptosis induced by endoplasmic reticulum stress. J Cell Biochem 2019; 120:7759-7770. [PMID: 30417434 DOI: 10.1002/jcb.28050] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 10/22/2018] [Indexed: 01/24/2023]
Abstract
Chronic exposure to high glucose induces endoplasmic reticulum (ER) stress in pancreatic beta cells (PBCs). The previous evidence showed that adenosine modulate PBCs viability and insulin secretion. The aim of this study was to evaluate possible involvement of adenosine in protection of MIN6 β-cells from Tunicamycin (Tu)-induced ER stress. MIN6 cells were cotreated with Tu and different concentrations of adenosine. Cell viability, proliferation, and apoptosis were evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT), 5-bromo-2'-deoxyuridine (Brdu), and colony formation assays. Caspase-12 activity was assayed using the fluorometric method. Thioflavin T (ThT) staining was used for the evaluation of protein aggregation. Insulin secretion was evaluated using specific an ELISA kit. Ca2+ mobilization assayed using Fura2/AM probe. BIP, CHOP, XBP-1, and XBP-1s expression in both messenger RNA (mRNA) and protein levels were evaluated using the reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Bcl-2, p-eIF2α/eIF2α, and GADD34 levels also determined with Western blot analysis. Adenosine protected MIN6 cells against Tu-induced ER stress in a dose-dependent manner and increased their proliferation. Decreased caspase-12 activity and upregulated Bcl-2 protein may explain antiapoptotic effects of adenosine. ThT staining indicated an attenuated aggregation of misfolded proteins. Adenosine effectively increased insulin secretion in Tu-treated cells. BIP, CHOP, XBP1, and sXBP1 expression were decreased significantly in cotreated cells, indicating alleviation of ER stress. However, adenosine potentiated the expression of GADD34 and decreased p-eIF2α/eIF2α ratio. Adenosine increased cytosolic Ca 2+ levels, which may promote adenosine triphosphate (ATP) synthesis in mitochondria, helping ER to preserve protein hemostasis. Taken together, adenosine upregulated Bcl-2 and GADD34 to protect PBCs against Tu-induced apoptosis and increase Insulin secretion.
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Affiliation(s)
- Mohammad Keyvanloo Shahrestanaki
- Department of Clinical Biochemistry, School of Pharmacy & Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Fatemeh Panahi Arasi
- Department of Clinical Biochemistry, School of Pharmacy & Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mahmoud Aghaei
- Department of Clinical Biochemistry, School of Pharmacy & Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
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20
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Cellular toxicity of dietary trans fatty acids and its correlation with ceramide and diglyceride accumulation. Food Chem Toxicol 2018; 124:324-335. [PMID: 30572061 DOI: 10.1016/j.fct.2018.12.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 11/21/2018] [Accepted: 12/14/2018] [Indexed: 01/01/2023]
Abstract
High fatty acid (FA) levels are deleterious to pancreatic β-cells, largely due to the accumulation of biosynthetic lipid intermediates, such as ceramides and diglycerides, which induce ER stress and apoptosis. Toxicity of palmitate (16:0) and oleate (18:1 cis-Δ9) has been widely investigated, while very little data is available on the cell damages caused by elaidate (18:1 trans-Δ9) and vaccenate (18:1 trans-Δ11), although the potential health effects of these dietary trans fatty acids (TFAs) received great publicity. We compared the effects of these four FAs on cell viability, apoptosis, ER stress, JNK phosphorylation and autophagy as well as on ceramide and diglyceride contents in RINm5F insulinoma cells. Similarly to oleate and unlike palmitate, TFAs reduced cell viability only at higher concentration, and they had mild effects on ER stress, apoptosis and autophagy. Palmitate increased ceramide and diglyceride levels far more than any of the unsaturated fatty acids; however, incorporation of TFAs in ceramides and diglycerides was strikingly more pronounced than that of oleate. This indicates a correlation between the accumulation of lipid intermediates and the severity of cell damage. Our findings reveal important metabolic characteristics of TFAs that might underlie a long term toxicity and hence deserve further investigation.
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21
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Chu KY, O'Reilly L, Mellet N, Meikle PJ, Bartley C, Biden TJ. Oleate disrupts cAMP signaling, contributing to potent stimulation of pancreatic β-cell autophagy. J Biol Chem 2018; 294:1218-1229. [PMID: 30518550 DOI: 10.1074/jbc.ra118.004833] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 11/19/2018] [Indexed: 12/12/2022] Open
Abstract
Autophagy is critical for maintaining cellular function via clearance of excess nutrients and damaged organelles. In pancreatic β-cells, it helps counter the endoplasmic reticulum (ER) stress that impairs insulin secretory capacity during Type 2 diabetes. Chronic exposure of β-cells to saturated fatty acids (FAs) such as palmitate stimulates ER stress and modulates autophagy, but the effects of unsaturated FAs such as oleate, which are also elevated during obesity, are less well understood. We therefore treated MIN6 cells and mouse islets for 8-48 h with either palmitate or oleate, and then monitored autophagic flux, signaling pathways, lysosomal biology, and phospholipid profiles. Compared with palmitate, oleate more effectively stimulated both autophagic flux and clearance of autophagosomes. The flux stimulation occurred independently of ER stress, nutrient-sensing (mTOR) and signaling pathways (protein kinases A, C, and D). Instead the mechanism involved the exchange factor directly activated by cAMP 2 (EPAC2). Oleate reduced cellular cAMP, and its effects on autophagic flux were reproduced or inhibited, respectively, by Epac2 knockdown or activation. Oleate also increased lysosomal acidity and increased phospholipid saturation, consistent with improved autophagosomal fusion with lysosomes. We conclude that a potent stimulation of autophagy might help explain the known benefits of unsaturated FAs in countering the toxicity of saturated FAs in β-cells during obesity and lipid loading.
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Affiliation(s)
- Kwan Yi Chu
- Division of Diabetes and Metabolism, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010; St. Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, NSW 2052
| | - Liam O'Reilly
- Division of Diabetes and Metabolism, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010
| | - Natalie Mellet
- Baker IDI Heart and Diabetes Institute, Prahran, Victoria 3004, Australia
| | - Peter J Meikle
- Baker IDI Heart and Diabetes Institute, Prahran, Victoria 3004, Australia
| | - Clarissa Bartley
- Division of Diabetes and Metabolism, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010
| | - Trevor J Biden
- Division of Diabetes and Metabolism, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010; St. Vincent's Clinical School, Faculty of Medicine, UNSW Sydney, NSW 2052.
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22
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Tang C, Yeung LSN, Koulajian K, Zhang L, Tai K, Volchuk A, Giacca A. Glucose-Induced β-Cell Dysfunction In Vivo: Evidence for a Causal Role of C-jun N-terminal Kinase Pathway. Endocrinology 2018; 159:3643-3654. [PMID: 30215691 PMCID: PMC6195676 DOI: 10.1210/en.2018-00566] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 08/26/2018] [Indexed: 11/19/2022]
Abstract
Prolonged elevation of glucose can adversely affect β-cell function. Oxidative stress, which has been implicated in glucose-induced β-cell dysfunction, can activate c-jun N-terminal kinase (JNK). However, whether JNK is causal in glucose-induced β-cell dysfunction in vivo is unclear. Therefore, we aimed at investigating the causal role of JNK activation in in vivo models of glucose-induced β-cell dysfunction. Glucose-induced β-cell dysfunction was investigated in the presence or absence of JNK inhibition. JNK inhibition was achieved using either (i) the JNK-specific inhibitor SP600125 or (ii) JNK-1-null mice. (i) Rats or mice were infused intravenously with saline or glucose with or without SP600125. (ii) JNK-1 null mice and their littermate wild-type controls were infused intravenously with saline or glucose. Following the glucose infusion periods in rats and mice, β-cell function was assessed in isolated islets or in vivo using hyperglycemic clamps. Forty-eight-hour hyperglycemia at ~20 mM in rats or 96-hour hyperglycemia at ~13 mM in mice impaired β-cell function in isolated islets and in vivo. Inhibition of JNK using either SP600125 or JNK-1-null mice prevented glucose-induced β-cell dysfunction in isolated islets and in vivo. Islets of JNK-1-null mice exposed to hyperglycemia in vivo showed an increase in Pdx-1 and insulin 2 mRNA, whereas islets of wild-type mice did not. Together, these data show that JNK pathway is involved in glucose-induced β-cell dysfunction in vivo and is thus a potential therapeutic target for type 2 diabetes.
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Affiliation(s)
- Christine Tang
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Lucy Shu Nga Yeung
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Khajag Koulajian
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Liling Zhang
- Division of Cellular and Molecular Biology, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Kevin Tai
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Allen Volchuk
- Keenan Research Centre for Biomedical Science, St. Michael Hospital, Toronto, Ontario, Canada
| | - Adria Giacca
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Correspondence: Adria Giacca, MD, Medical Sciences Building, 3336-1 King’s College Circle, Toronto, Ontario M5S 1A8, Canada. E-mail:
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23
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Jiang Y, Wang Z, Ma B, Fan L, Yi N, Lu B, Wang Q, Liu R. GLP-1 Improves Adipocyte Insulin Sensitivity Following Induction of Endoplasmic Reticulum Stress. Front Pharmacol 2018; 9:1168. [PMID: 30459598 PMCID: PMC6232689 DOI: 10.3389/fphar.2018.01168] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 09/26/2018] [Indexed: 01/05/2023] Open
Abstract
Glucagon-like peptide 1 (GLP-1) improves insulin resistance of adipose tissue in obese humans. However, the mechanism of this effect is unclear. Perturbation of endoplasmic reticulum (ER) homeostasis impairs insulin signaling. We hypothesized that GLP-1 could directly improve insulin signaling in ER-stressed adipocytes. Here, we examined the effects of GLP-1 on ER stress response in fat cells in an obese and insulin-resistant murine model. We found that GLP-1 analog liraglutide reduced ER stress related gene expression in visceral fat cells accompanied by improved systemic insulin tolerance. Consistently, GLP-1 decreased CHOP expression and increased insulin stimulated AKT phosphorylation (p-AKT) in thapsigargin, a ER stress inducer, treated white fat cells differentiated from visceral stromal vascular fraction. We further found blocking CHOP expression increased insulin stimulated p-AKT in ER-stressed fat cells. Of note, we found mTOR signaling pathway contributed to the expression of ATF4 and subsequently the CHOP expression in ER stress response, while GLP-1 inhibited mTOR activity as exemplified by elevated autophagosome formation and increased LC3II/LC3I ratio. These findings suggest that GLP-1 directly modulates the ER stress response partially via inhibiting mTOR signaling pathway, leading to increased insulin sensitivity in adipocytes.
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Affiliation(s)
- Yaojing Jiang
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai, China
| | - Zhihong Wang
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai, China
| | - Bo Ma
- Department of Obstetrics and Gynecology, Tianjin Central Hospital of Gynecology Obstetrics, Tianjin, China
| | - Linling Fan
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai, China
| | - Na Yi
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai, China
| | - Bin Lu
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai, China
| | - Qinghua Wang
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai, China.,Division of Endocrinology and Metabolism, Keenan Research Centre for Biomedical Science of St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Rui Liu
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai, China
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24
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Li Z, Liu H, Niu Z, Zhong W, Xue M, Wang J, Yang F, Zhou Y, Zhou Y, Xu T, Hou J. Temporal Proteomic Analysis of Pancreatic β-Cells in Response to Lipotoxicity and Glucolipotoxicity. Mol Cell Proteomics 2018; 17:2119-2131. [PMID: 30082485 DOI: 10.1074/mcp.ra118.000698] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 08/03/2018] [Indexed: 12/12/2022] Open
Abstract
Chronic hyperlipidemia causes the dysfunction of pancreatic β-cells, such as apoptosis and impaired insulin secretion, which are aggravated in the presence of hyperglycemia. The underlying mechanisms, such as endoplasmic reticulum (ER) stress, oxidative stress and metabolic disorders, have been reported before; however, the time sequence of these molecular events is not fully understood. Here, using isobaric labeling-based mass spectrometry, we investigated the dynamic proteomes of INS-1 cells exposed to high palmitate in the absence and presence of high glucose. Using bioinformatics analysis of differentially expressed proteins, including the time-course expression pattern, protein-protein interaction, gene set enrichment and KEGG pathway analysis, we analyzed the dynamic features of previously reported and newly identified lipotoxicity- and glucolipotoxicity-related molecular events in more detail. Our temporal data highlight cholesterol metabolism occurring at 4 h, earlier than fatty acid metabolism that started at 8 h and likely acting as an early toxic event highly associated with ER stress induced by palmitate. Interestingly, we found that the proliferation of INS-1 cells was significantly increased at 48 h by combined treatment of palmitate and glucose. Moreover, benefit from the time-course quantitative data, we identified and validated two new molecular targets: Setd8 for cell replication and Rhob for apoptosis, demonstrating that our temporal dataset serves as a valuable resource to identify potential candidates for mechanistic studies of lipotoxicity and glucolipotoxicity in pancreatic β-cells.
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Affiliation(s)
- Zonghong Li
- From the ‡National Laboratory of Biomacramolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,§Jilin Province Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun, 130024, China
| | - Hongyang Liu
- From the ‡National Laboratory of Biomacramolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,‖Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhangjing Niu
- From the ‡National Laboratory of Biomacramolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,‖Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen Zhong
- ***College of Life Science and Technology, HuaZhong University of Science and Technology, Wuhan 430074, China
| | - Miaomiao Xue
- From the ‡National Laboratory of Biomacramolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,¶College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jifeng Wang
- ‡‡Laboratory of Protein and Peptide Pharmaceuticals and Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Fuquan Yang
- ‡‡Laboratory of Protein and Peptide Pharmaceuticals and Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,¶College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yue Zhou
- §§ThermoFisher Scientific, Building 6, No. 27, Xin Jinqiao Rd, Pudong, Shanghai, 201206, China
| | - Yifa Zhou
- §Jilin Province Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun, 130024, China;
| | - Tao Xu
- From the ‡National Laboratory of Biomacramolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; .,¶College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junjie Hou
- From the ‡National Laboratory of Biomacramolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China;
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25
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Choi S, Snider JM, Olakkengil N, Lambert JM, Anderson AK, Ross-Evans JS, Cowart LA, Snider AJ. Myristate-induced endoplasmic reticulum stress requires ceramide synthases 5/6 and generation of C14-ceramide in intestinal epithelial cells. FASEB J 2018; 32:5724-5736. [PMID: 29768040 DOI: 10.1096/fj.201800141r] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Saturated fatty acids (SFAs) have been shown to induce endoplasmic reticulum (ER) stress and chronic inflammatory responses, as well as alter sphingolipid metabolism. Disruptions in ER stress and sphingolipid metabolism have also been implicated in intestinal inflammation. Therefore, to elucidate the roles of SFAs in ER stress and inflammation in intestinal epithelial cells, we examined myristate (C14:0) and palmitate (C16:0). Myristate, but not palmitate, induced ER stress signaling, including activation of inositol-requiring enzyme 1 (IRE1) and X-box binding protein 1 (XBP1) signaling. Myristate significantly increased C14-ceramide levels, whereas palmitate increased several long-chain ceramides. To define the role of ceramide synthases (CerSs) in myristate-induced ER stress, we used the pharmacologic inhibitor, fumonisin B1 (FB1), and small interfering RNA (siRNA) for CerS5 and 6, the primary isoforms that are involved in C14-ceramide generation. FB1 and siRNA for CerS5 or 6 suppressed myristate-induced C14-ceramide generation and XBP1 splicing (XBP1s). Moreover, increased XBP1s induced the downstream expression of IL-6 in a CerS5/6-dependent manner. In addition, a myristate-enriched milk fat-based diet, but not a lard-based diet, increased C14-ceramide, XBP1s, and IL-6 expression in vivo. Taken together, our data suggest that myristate modulates ER stress and cytokine production in the intestinal epithelium via CerS5/6 and C14-ceramide generation.-Choi, S., Snider, J. M., Olakkengil, N., Lambert, J. M., Anderson, A. K., Ross-Evans, J. S., Cowart, L. A., Snider, A. J. Myristate-induced endoplasmic reticulum stress requires ceramide synthases 5/6 and generation of C14-ceramide in intestinal epithelial cells.
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Affiliation(s)
- Songhwa Choi
- Department of Biochemistry, Stony Brook University, Stony Brook, New York, USA.,Department of Medicine, Stony Brook University, Stony Brook, New York, USA
| | - Justin M Snider
- Department of Biochemistry, Stony Brook University, Stony Brook, New York, USA.,Department of Medicine, Stony Brook University, Stony Brook, New York, USA
| | - Nicole Olakkengil
- Department of Biochemistry, Stony Brook University, Stony Brook, New York, USA
| | - Johana M Lambert
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA.,Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Andrea K Anderson
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA.,Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Jessica S Ross-Evans
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - L Ashley Cowart
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia, USA.,Hunter Holmes McGuire Veterans' Affairs Medical Center, Richmond, Virginia, USA
| | - Ashley J Snider
- Department of Medicine, Stony Brook University, Stony Brook, New York, USA.,Cancer Center, Stony Brook University, Stony Brook, New York, USA.,Northport Veterans Affairs Medical Center, Northport, New York, USA
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26
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Jiang H, Ma Y, Fu L, Wang J, Wang L, Fan M, Huang K, Zhang Y, Peng H. Influence of lipopolysaccharides on autophagy and inflammation in pancreatic islet cells of mice fed by high-fat diet. EUR J INFLAMM 2018. [DOI: 10.1177/1721727x17754180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The aim of this study was to confirm whether chronic low-grade inflammation could induce autophagy and damage in islet cells. The high-fat diet (HF) and low-dose lipopolysaccharides (LPS) were used to simulate chronic inflammation. Islet function was observed, the expression of autophagy-related proteins and the activity of glucose synthase kinase 3β (GSK-3β) were detected, and the role of autophagy in islet injury induced by inflammation was explored. Higher blood glucose was observed in HF group and LPS group compared with control (C) group, and there was no significant difference between LPS group and LiCl group. The apoptotic pancreatic islet cells in the LPS group were higher than in the HF and C groups, and the in the LiCl group they were higher than in the C group and lower than in the LPS group. Compared with the C group, LC3II/I ratio in the HF group was increased ( P < 0.05), in LPS and LiCl groups it was lower than in the HF group, and in LiCl group it was higher than in the LPS group. There was no significant difference between HF group and C group with regard to the ratio of p-GSK-3β/GSK-3β, but in the LiCl group it was higher than in the LPS group. The results demonstrated that low-grade inflammation might cause autophagy flux impaired through activation of GSK-3β, and induced islet cells damage. LiCl could play a role in protecting islet cells through autophagy enhancement.
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Affiliation(s)
- Hongwei Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Yujin Ma
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Liujun Fu
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Jie Wang
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Linlei Wang
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Menglin Fan
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Ke Huang
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Yingyu Zhang
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
| | - Huifang Peng
- Department of Endocrinology, Key Laboratory of Endocrinology Genetic and Metabolic Diseases of Luoyang, Clinical Medicine Research Center for Endocrine and Metabolic Disease of Luoyang, Academician Workstation for Diabetic Kidney Disease Research of Henan Province, The First Affiliated Hospital, and College of Clinical Medicine, Henan University of Science and Technology, Luoyang, China
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27
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Ahlstrom P, Rai E, Chakma S, Cho HH, Rengasamy P, Sweeney G. Adiponectin improves insulin sensitivity via activation of autophagic flux. J Mol Endocrinol 2017; 59:339-350. [PMID: 28954814 DOI: 10.1530/jme-17-0096] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 09/04/2017] [Indexed: 12/26/2022]
Abstract
Skeletal muscle insulin resistance is known to play an important role in the pathogenesis of diabetes, and one potential causative cellular mechanism is endoplasmic reticulum (ER) stress. Adiponectin mediates anti-diabetic effects via direct metabolic actions and by improving insulin sensitivity, and we recently demonstrated an important role in stimulation of autophagy by adiponectin. However, there is limited knowledge on crosstalk between autophagy and ER stress in skeletal muscle and in particular how they are regulated by adiponectin. Here, we utilized the model of high insulin/glucose (HIHG)-induced insulin resistance, determined by measuring Akt phosphorylation (T308 and S473) and glucose uptake in L6 skeletal muscle cells. HIHG reduced autophagic flux measured by LC3 and p62 Western blotting and tandem fluorescent RFP/GFP-LC3 immunofluorescence (IF). HIHG also induced ER stress assessed by thioflavin T/KDEL IF, pIRE1, pPERK, peIF2α and ATF6 Western blotting and induction of a GRP78-mCherry reporter. Induction of autophagy by adiponectin or rapamycin attenuated HIHG-induced ER stress and improved insulin sensitivity. The functional significance of enhanced autophagy was validated by demonstrating a lack of improved insulin sensitivity in response to adiponectin in autophagy-deficient cells generated by overexpression of dominant negative mutant of Atg5. In summary, adiponectin-induced autophagy in skeletal muscle cells alleviated HIHG-induced ER stress and insulin resistance.
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Affiliation(s)
| | - Esther Rai
- Department of BiologyYork University, Toronto, Canada
| | | | - Hee Ho Cho
- Department of BiologyYork University, Toronto, Canada
| | | | - Gary Sweeney
- Department of BiologyYork University, Toronto, Canada
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Colvin BN, Longtine MS, Chen B, Costa ML, Nelson DM. Oleate attenuates palmitate-induced endoplasmic reticulum stress and apoptosis in placental trophoblasts. Reproduction 2017; 153:369-380. [PMID: 28159805 DOI: 10.1530/rep-16-0576] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/02/2016] [Accepted: 01/03/2017] [Indexed: 12/24/2022]
Abstract
Pre-pregnancy obesity is increasingly common and predisposes pregnant women and offspring to gestational diabetes, pre-eclampsia, fetal growth abnormalities and stillbirth. Obese women exhibit elevated levels of the two most common dietary fatty acids, palmitate and oleate, and the maternal blood containing these nutrients bathes the surface of trophoblasts of placental villi in vivo We test the hypothesis that the composition and concentration of free fatty acids modulate viability and function of primary human villous trophoblasts in culture. We found that palmitate increases syncytiotrophoblast death, specifically by caspase-mediated apoptosis, whereas oleate does not cause enhanced cell death. Importantly, exposure to both fatty acids in equimolar amounts yielded no increase in death or apoptosis, suggesting that oleate can protect syncytiotrophoblasts from palmitate-induced death. We further found that palmitate, but not oleate or oleate with palmitate, increases endoplasmic reticulum (ER) stress, signaling through the unfolded protein response, and yielding CHOP-mediated induction of apoptosis. Finally, we show that oleate or oleate plus palmitate both lead to increased lipid droplets in syncytiotrophoblasts, whereas palmitate does not. The data show palmitate is toxic to human syncytiotrophoblasts, through the induction of ER stress and apoptosis mediated by CHOP, whereas oleate is not toxic, abrogates palmitate toxicity and induces fat accumulation. We speculate that our in vitro results offer pathways by which the metabolic milieu of the obese pregnant woman can yield villous trophoblast dysfunction and sub-optimal placental function.
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Affiliation(s)
| | - Mark S Longtine
- Department of Obstetrics and GynecologyWashington University School of Medicine, St Louis, Missouri, USA
| | - Baosheng Chen
- Department of Obstetrics and GynecologyWashington University School of Medicine, St Louis, Missouri, USA
| | - Maria Laura Costa
- Department of Obstetrics and GynecologyWashington University School of Medicine, St Louis, Missouri, USA.,Department of Obstetrics and GynecologyUniversidade Estadual de Campinas, Cidade Universitaria Zeferino Vaz, Campinas, Brazil
| | - D Michael Nelson
- Department of Obstetrics and GynecologyWashington University School of Medicine, St Louis, Missouri, USA
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Palmitate induces myocardial lipotoxic injury via the endoplasmic reticulum stress-mediated apoptosis pathway. Mol Med Rep 2017; 16:6934-6939. [DOI: 10.3892/mmr.2017.7404] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 07/13/2017] [Indexed: 11/05/2022] Open
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Velasquez C, Vasquez JS, Balcazar N. In Vitro Effect of Fatty Acids Identified in the Plasma of Obese Adolescents on the Function of Pancreatic β-Cells. Diabetes Metab J 2017; 41:303-315. [PMID: 28868828 PMCID: PMC5583408 DOI: 10.4093/dmj.2017.41.4.303] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 01/31/2017] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND The increase in circulating free fatty acid (FFA) levels is a major factor that induces malfunction in pancreatic β-cells. We evaluated the effect of FFAs reconstituted according to the profile of circulating fatty acids found in obese adolescents on the viability and function of the murine insulinoma cell line (mouse insulinoma [MIN6]). METHODS From fatty acids obtained commercially, plasma-FFA profiles of three different youth populations were reconstituted: obese with metabolic syndrome; obese without metabolic syndrome; and normal weight without metabolic syndrome. MIN6 cells were treated for 24 or 48 hours with the three FFA profiles, and glucose-stimulated insulin secretion, cell viability, mitochondrial function and antioxidant activity were evaluated. RESULTS The high FFA content and high polyunsaturated ω6/ω3 ratio, present in plasma of obese adolescents with metabolic syndrome had a toxic effect on MIN6 cell viability and function, increasing oxidative stress and decreasing glucose-dependent insulin secretion. CONCLUSION These results could help to guide nutritional management of obese young individuals, encouraging the increase of ω-3-rich food consumption in order to reduce the likelihood of deterioration of β-cells and the possible development of type 2 diabetes mellitus.
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Affiliation(s)
- Claudia Velasquez
- Research Group in Food and Human Nutrition, School of Dietetics and Human Nutrition, University of Antioquia, Medellin, Colombia
| | | | - Norman Balcazar
- Genetics Molecular Group, University of Antioquia, Medellin, Colombia
- Department of Physiology and Biochemistry, School of Medicine, University of Antioquia, Medellin, Colombia.
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The Novel Mechanisms Concerning the Inhibitions of Palmitate-Induced Proinflammatory Factor Releases and Endogenous Cellular Stress with Astaxanthin on MIN6 β-Cells. Mar Drugs 2017. [PMID: 28632169 PMCID: PMC5484135 DOI: 10.3390/md15060185] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Astaxanthin, an antioxidant agent, can protect pancreatic β-cells of db/db mice from glucotoxicity and resolve chronic inflammation in adipose tissue. Nonetheless, the effects of astaxanthin on free-fatty-acid-induced inflammation and cellular stress in β-cells remain to be demonstrated. Meanwhile, palmitate enhances the secretion of pro-inflammatory adipokines monocyte chemoattractant protein-1 (MCP-1) and vascular endothelial growth factor (VEGF120). We therefore investigated the influence of astaxanthin on palmitate-stimulated MCP-1 and VEGF120 secretion in mouse insulinoma (MIN6) pancreatic β-cells. Furthermore, whether astaxanthin prevents cellular stress in MIN6 cells was also assessed. Pre-treatment with astaxanthin or with N-acetyl-cysteine (NAC) which is an antioxidant drug, significantly attenuated the palmitate-induced MCP-1 release through downregulation of phosphorylated c-Jun NH2-terminal protein kinase (JNK) pathways, and suppressed VEGF120 through the PI3K/Akt pathways relative to the cells stimulated with palmitate alone. In addition, palmitate significantly upregulated homologous protein (CHOP) and anti-glucose-regulated protein (GRP78), which are endoplasmic reticulum (ER) stress markers, in MIN6 cells. On the other hand, astaxanthin attenuated the increased CHOP content, but further up-regulated palmitate-stimulated GRP78 protein expression. By contrast, NAC had no effects on either CHOP or GRP78 enhancement induced by palmitate in MIN6 cells. In conclusion, astaxanthin diminishes the palmitate-stimulated increase in MCP-1 secretion via the downregulation of JNK pathways in MIN6 cells, and affects VEGF120 secretion through PI3K/Akt pathways. Moreover, astaxanthin can prevent not only oxidative stress caused endogenously by palmitate but also ER stress, which NAC fails to attenuate, via upregulation of GRP78, an ER chaperon.
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Geng F, Guo D. Lipid droplets, potential biomarker and metabolic target in glioblastoma. INTERNAL MEDICINE REVIEW (WASHINGTON, D.C. : ONLINE) 2017; 3:10.18103/imr.v3i5.443. [PMID: 29034362 PMCID: PMC5639724 DOI: 10.18103/imr.v3i5.443] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Lipid droplets (LDs) are subcellular organelles that store large amounts of the neutral lipids, triglycerides (TG) and/or cholesteryl esters (CE). LDs are commonly formed in adipocytes, liver cells and macrophages, and their formation has been shown to be associated with the progression of metabolic diseases, i.e., obesity, fatty liver and atherosclerosis. Interestingly, LDs are also found in some tumor tissues. We recently showed that LDs are prevalent in glioblastoma (GBM), the most deadly brain tumor, but are not detectable in low-grade gliomas and normal brain tissues, suggesting that LDs may serve as a novel diagnostic biomarker for GBM. This short review will briefly introduce LD biology, summarize recent observations about LDs in several types of cancer tissues, and discuss LD formation in GBM. Moreover, we will highlight the role of SOAT1 (sterol-O transferase 1), a key enzyme regulating CE synthesis and LD formation in GBM, in the regulation of SREBP (sterol regulatory-element binding protein) activation. The therapeutic potential of LDs and SOAT1 will be discussed.
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Affiliation(s)
- Feng Geng
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Columbus, OH 43210, USA
| | - Deliang Guo
- Department of Radiation Oncology, The Ohio State University James Comprehensive Cancer Center and College of Medicine, Columbus, OH 43210, USA
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Kuzmenko DI, Klimentyeva TK. Role of Ceramide in Apoptosis and Development of Insulin Resistance. BIOCHEMISTRY (MOSCOW) 2017; 81:913-27. [PMID: 27682164 DOI: 10.1134/s0006297916090017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This review presents data on the functional biochemistry of ceramide, one of the key sphingolipids with properties of a secondary messenger. Molecular mechanisms of the involvement of ceramide in apoptosis in pancreatic β-cells and its role in the formation of insulin resistance in pathogenesis of type 2 diabetes are reviewed. One of the main predispositions for the development of insulin resistance and diabetes is obesity, which is associated with ectopic fat deposition and significant increase in intracellular concentrations of cytotoxic ceramides. A possible approach to the restoration of tissue sensitivity to insulin in type 2 diabetes based on selective reduction of the content of cytotoxic ceramides is discussed.
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Affiliation(s)
- D I Kuzmenko
- Siberian State Medical University, Ministry of Healthcare of the Russian Federation, Tomsk, 634050, Russia.
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Semiane N, Foufelle F, Ferré P, Hainault I, Ameddah S, Mallek A, Khalkhal A, Dahmani Y. High carbohydrate diet induces nonalcoholic steato-hepatitis (NASH) in a desert gerbil. C R Biol 2017; 340:25-36. [DOI: 10.1016/j.crvi.2016.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/06/2016] [Accepted: 09/07/2016] [Indexed: 02/07/2023]
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Ahn M, Yoder SM, Wang Z, Oh E, Ramalingam L, Tunduguru R, Thurmond DC. The p21-activated kinase (PAK1) is involved in diet-induced beta cell mass expansion and survival in mice and human islets. Diabetologia 2016; 59:2145-55. [PMID: 27394663 PMCID: PMC5266538 DOI: 10.1007/s00125-016-4042-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 06/10/2016] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS Human islets from type 2 diabetic donors are reportedly 80% deficient in the p21 (Cdc42/Rac)-activated kinase, PAK1. PAK1 is implicated in beta cell function and maintenance of beta cell mass. We questioned the mechanism(s) by which PAK1 deficiency potentially contributes to increased susceptibility to type 2 diabetes. METHODS Non-diabetic human islets and INS 832/13 beta cells cultured under diabetogenic conditions (i.e. with specific cytokines or under glucolipotoxic [GLT] conditions) were evaluated for changes to PAK1 signalling. Combined effects of PAK1 deficiency with GLT stress were assessed using classic knockout (Pak1 (-/-) ) mice fed a 45% energy from fat/palmitate-based, 'western' diet (WD). INS 832/13 cells overexpressing or depleted of PAK1 were also assessed for apoptosis and signalling changes. RESULTS Exposure of non-diabetic human islets to diabetic stressors attenuated PAK1 protein levels, concurrent with increased caspase 3 cleavage. WD-fed Pak1 knockout mice exhibited fasting hyperglycaemia and severe glucose intolerance. These mice also failed to mount an insulin secretory response following acute glucose challenge, coinciding with a 43% loss of beta cell mass when compared with WD-fed wild-type mice. Pak1 knockout mice had fewer total beta cells per islet, coincident with decreased beta cell proliferation. In INS 832/13 beta cells, PAK1 deficiency combined with GLT exposure heightened beta cell death relative to either condition alone; PAK1 deficiency resulted in decreased extracellular signal-related kinase (ERK) and B cell lymphoma 2 (Bcl2) phosphorylation levels. Conversely, PAK1 overexpression prevented GLT-induced cell death. CONCLUSIONS/INTERPRETATION These findings suggest that PAK1 deficiency may underlie an increased diabetic susceptibility. Discovery of ways to remediate glycaemic dysregulation via altering PAK1 or its downstream effectors offers promising opportunities for disease intervention.
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Affiliation(s)
- Miwon Ahn
- Department of Molecular & Cellular Endocrinology, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd., Duarte, CA, 91010, USA
| | - Stephanie M Yoder
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Zhanxiang Wang
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Eunjin Oh
- Department of Molecular & Cellular Endocrinology, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd., Duarte, CA, 91010, USA
| | - Latha Ramalingam
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ragadeepthi Tunduguru
- Department of Molecular & Cellular Endocrinology, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd., Duarte, CA, 91010, USA
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Debbie C Thurmond
- Department of Molecular & Cellular Endocrinology, Beckman Research Institute of City of Hope, 1500 E. Duarte Rd., Duarte, CA, 91010, USA.
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA.
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
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Duan Q, Ni L, Wang P, Chen C, Yang L, Ma B, Gong W, Cai Z, Zou M, Wang DW. Deregulation of XBP1 expression contributes to myocardial vascular endothelial growth factor-A expression and angiogenesis during cardiac hypertrophy in vivo. Aging Cell 2016; 15:625-33. [PMID: 27133203 PMCID: PMC4933664 DOI: 10.1111/acel.12460] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2016] [Indexed: 01/18/2023] Open
Abstract
Endoplasmic reticulum (ER) stress has been reported to be involved in many cardiovascular diseases such as atherosclerosis, diabetes, myocardial ischemia, and hypertension that ultimately result in heart failure. XBP1 is a key ER stress signal transducer and an important pro‐survival factor of the unfolded protein response (UPR) in mammalian cells. The aim of this study was to establish a role for XBP1 in the deregulation of pro‐angiogenic factor VEGF expression and potential regulatory mechanisms in hypertrophic and failing heart. Western blots showed that myocardial XBP1s protein was significantly increased in both isoproterenol (ISO)‐induced and pressure‐overload‐induced hypertrophic and failing heart compared to normal control. Furthermore, XBP1 silencing exacerbates ISO‐induced cardiac dysfunction along with a reduction of myocardial capillary density and cardiac expression of pro‐angiogenic factor VEGF‐A in vivo. Consistently, experiments in cultured cardiomyocytes H9c2 (2‐1) cells showed that UPR‐induced VEGF‐A upregulation was determined by XBP1 expression level. Importantly, VEGF‐A expression was increased in failing human heart tissue and blood samples and was correlated with the levels of XBP1. These results suggest that XBP1 regulates VEGF‐mediated cardiac angiogenesis, which contributes to the progression of adaptive hypertrophy, and might provide novel targets for prevention and treatment of heart failure.
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Affiliation(s)
- Quanlu Duan
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Li Ni
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Peihua Wang
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Chen Chen
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Lei Yang
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Ben Ma
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Wei Gong
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Zhejun Cai
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
| | - Ming‐Hui Zou
- Center for Molecular and Translational Medicine Georgia State University Atlanta 30303 GA USA
| | - Dao Wen Wang
- Division of Cardiology, Department Internal Medicine, Tongji Hospital Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030 People's Republic of China
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An YW, Zhan ZL, Xie J, Yang YN, Jiang JS, Feng ZM, Ye F, Zhang PC. Bioactive Octahydroxylated C21 Steroids from the Root Bark of Lycium chinense. JOURNAL OF NATURAL PRODUCTS 2016; 79:1024-1034. [PMID: 26982999 DOI: 10.1021/acs.jnatprod.5b01087] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Lyciumsterols A-K (1-11), 11 new octahydroxylated C21 steroids, were isolated from the root bark of Lycium chinense, along with 15 known compounds. Characterization of these C21 steroids showed the presence of eight hydroxy groups on the C21 steroid skeleton with a (2E,4E)-5-phenyl-2,4-pentadienoate group at C-12 or C-20 and various 2,6-deoxy sugar residues at C-3. The structures of these compounds were elucidated using spectroscopic data interpretation. Compounds 2, 3, and 7 exhibited dose-dependent protective effects on pancreatic islet cells and may help to improve cell viability. In addition, it was found that compounds 7, 8, 9, and 11 exhibited autophagy activation.
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Affiliation(s)
- Ya-Wen An
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
| | - Zhi-Lai Zhan
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences , Beijing 100700, People's Republic of China
| | - Jing Xie
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
| | - Ya-Nan Yang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
| | - Jian-Shuang Jiang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
| | - Zi-Ming Feng
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
| | - Fei Ye
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
| | - Pei-Cheng Zhang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, People's Republic of China
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Curcumin attenuates palmitate-induced apoptosis in MIN6 pancreatic β-cells through PI3K/Akt/FoxO1 and mitochondrial survival pathways. Apoptosis 2016; 20:1420-32. [PMID: 26330141 DOI: 10.1007/s10495-015-1150-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Lipotoxicity plays a vital role in development and progression of type 2 diabetes. Prolonged elevation of free fatty acids especially the palmitate leads to pancreatic β-cell dysfunction and apoptosis. Curcumin (diferuloylmethane), a polyphenol from the curry spice turmeric, is considered to be a broadly cytoprotective agent. The present study was designed to determine the protective effect of curcumin on palmitate-induced apoptosis in β-cells and investigate underlying mechanisms. Our results showed that curcumin improved cell viability and enhanced glucose-induced insulin secretory function in MIN6 pancreatic β-cells. Palmitate incubation evoked chromatin condensation, DNA nick end labeling and activation of caspase-3 and -9. Curcumin treatment inhibited palmitate-induced apoptosis, relieved mitochondrial depolarization and up-regulated Bcl-2/Bax ratio. Palmitate induced the generation of reactive oxygen species and inhibited activities of antioxidant enzymes, which could be neutralized by curcumin treatment. Moreover, curcumin could promote rapid phosphorylation of Akt and nuclear exclusion of FoxO1 in MIN6 cells under lipotoxic condition. Phosphatidylinositol 3-kinase and Akt specific inhibitors abolished the anti-lipotoxic effect of curcumin and stimulated FoxO1 nuclear translocation. These findings suggested that curcumin protected MIN6 pancreatic β-Cells against apoptosis through activation of Akt, inhibition of nuclear translocation of FoxO1 and mitochondrial survival pathway.
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Anti-diabetic effect of 3-hydroxy-2-naphthoic acid, an endoplasmic reticulum stress-reducing chemical chaperone. Eur J Pharmacol 2016; 779:157-67. [PMID: 26983645 DOI: 10.1016/j.ejphar.2016.03.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/11/2016] [Accepted: 03/11/2016] [Indexed: 01/22/2023]
Abstract
Lots of experimental and clinical evidences indicate that chronic exposure to saturated fatty acids and high level of glucose is implicated in insulin resistance, beta cell failure and ultimately type 2 diabetes. In this study, we set up cell-based experimental conditions to induce endoplasmic reticulum (ER) stress and insulin resistance using high concentration of palmitate (PA). Hydroxynaphthoic acids (HNAs) were formerly identified as novel chemical chaperones to resolve ER stress induced by tunicamycin. In this study, we found the compounds have the same suppressive effect on PA-induced ER stress in HepG2 cells. The representing compound, 3-HNA reduced PA-induced phosphorylation of JNK, IKKβ and IRS1 (S307) and restored insulin signaling cascade which involves insulin receptor β, IRS1 and Akt. The insulin sensitizing effect of 3-HNA was confirmed in 3T3-L1 adipocytes, where the compound augmented insulin signaling and glucose transporter 4 (GLUT4) membrane translocation. 3-HNA also protected the pancreatic beta cells from PA-induced apoptosis by reducing ER stress. Upon 3-HNA treatment to ob/ob mice at 150mg/kg/day dosage, the diabetic parameters including glucose tolerance and systemic insulin sensitivity were significantly improved. Postmortem examination showed that 3-HNA markedly reduced ER stress and insulin resistance in the liver tissues and it sensitized insulin signaling in the liver and the skeletal muscle. Our results demonstrated that 3-HNA can sensitize insulin signaling by coping with lipotoxicity-induced ER stress as a chemical chaperone and suggested it holds therapeutic potential for insulin resistance and type 2 diabetes.
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p38 MAPK Is Activated but Does Not Play a Key Role during Apoptosis Induction by Saturated Fatty Acid in Human Pancreatic β-Cells. Int J Mol Sci 2016; 17:159. [PMID: 26861294 PMCID: PMC4783893 DOI: 10.3390/ijms17020159] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 12/29/2015] [Accepted: 01/22/2016] [Indexed: 12/25/2022] Open
Abstract
Saturated stearic acid (SA) induces apoptosis in the human pancreatic β-cells NES2Y. However, the molecular mechanisms involved are unclear. We showed that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway in these cells. Therefore, we tested the role of p38 MAPK signaling pathway activation in apoptosis induction by SA in NES2Y cells. Crosstalk between p38 MAPK pathway activation and accompanying ERK pathway inhibition after SA application was also tested. The inhibition of p38 MAPK expression by siRNA silencing resulted in a decrease in MAPKAPK-2 activation after SA application, but it had no significant effect on cell viability or the level of phosphorylated ERK pathway members. The inhibition of p38 MAPK activity by the specific inhibitor SB202190 resulted in inhibition of MAPKAPK-2 activation and noticeable activation of ERK pathway members after SA treatment but in no significant effect on cell viability. p38 MAPK overexpression by plasmid transfection produced an increase in MAPKAPK-2 activation after SA exposure but no significant influence on cell viability or ERK pathway activation. The activation of p38 MAPK by the specific activator anisomycin resulted in significant activation of MAPKAPK-2. Concerning the effect on cell viability, application of the activator led to apoptosis induction similar to application of SA (PARP cleavage and caspase-7, -8, and -9 activation) and in inhibition of ERK pathway members. We demonstrated that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway and that this activation could be involved in apoptosis induction by SA in the human pancreatic β-cells NES2Y. However, this involvement does not seem to play a key role. Crosstalk between p38 MAPK pathway activation and ERK pathway inhibition in NES2Y cells seems likely. Thus, the ERK pathway inhibition by p38 MAPK activation does not also seem to be essential for SA-induced apoptosis.
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Tang B, Li Q, Zhao XH, Wang HG, Li N, Fang Y, Wang K, Jia YP, Zhu P, Gu J, Li JX, Jiao YJ, Tong WD, Wang M, Zou QM, Zhu FC, Mao XH. Shiga toxins induce autophagic cell death in intestinal epithelial cells via the endoplasmic reticulum stress pathway. Autophagy 2016; 11:344-54. [PMID: 25831014 DOI: 10.1080/15548627.2015.1023682] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Shiga toxins (Stxs) are a family of cytotoxic proteins that lead to the development of bloody diarrhea, hemolytic-uremic syndrome, and central nervous system complications caused by bacteria such as S. dysenteriae, E. coli O157:H7 and E. coli O104:H4. Increasing evidence indicates that macroautophagy (autophagy) is a key factor in the cell death induced by Stxs. However, the associated mechanisms are not yet clear. This study showed that Stx2 induces autophagic cell death in Caco-2 cells, a cultured line model of human enterocytes. Inhibition of autophagy using pharmacological inhibitors, such as 3-methyladenine and bafilomycin A1, or silencing of the autophagy genes ATG12 or BECN1 decreased the Stx2-induced death in Caco-2 cells. Furthermore, there were numerous instances of dilated endoplasmic reticulum (ER) in the Stx2-treated Caco-2 cells, and repression of ER stress due to the depletion of viable candidates of DDIT3 and NUPR1. These processes led to Stx2-induced autophagy and cell death. Finally, the data showed that the pseudokinase TRIB3-mediated DDIT3 expression and AKT1 dephosphorylation upon ER stress were triggered by Stx2. Thus, the data indicate that Stx2 causes autophagic cell death via the ER stress pathway in intestinal epithelial cells.
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Key Words
- 3-MA, 3-methyladenine
- AO, acridine orange
- ATF4, activating transcription factor 4
- ATG, autophagy-related
- BECN1, Beclin 1, autophagy-related
- Baf A1, bafilomycin A1
- CASP3, caspase 3, apoptosis-related cysteine peptidase
- DDIT3, DNA-damage-inducible transcript 3
- E. coli O157:H7
- EHEC O157, Escherichia coli O157:H7
- ER stress
- FACS, fluorescence activated cell sorting
- MAP1LC3B, microtubule-associated protein 1 light chain 3 beta
- MAPK, mitogen-activated protein kinase
- MDC, monodansylcadaverine
- NUPR1, nuclear protein, transcriptional regulator, 1
- PARP1, poly (ADP-ribose) polymerase 1
- PBS, phosphate-buffered saline
- PI, propidium iodide
- Shiga toxins
- Stxs, Shiga toxins
- TEM, transmission electron microscopy
- TRIB3, tribbles pseudokinase 3
- Thap, thapsigargin
- WT, wild type
- Z-VAD, Z-VAD-FMK
- autophagic cell death
- autophagy
- Δ, knockout
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Affiliation(s)
- Bin Tang
- a National Engineering Research Center for Immunobiological Products; Department of Microbiology and Biochemical Pharmacy; College of Pharmacy; Third Military Medical University ; Chongqing , China
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Cohen G, Shamni O, Avrahami Y, Cohen O, Broner EC, Filippov-Levy N, Chatgilialoglu C, Ferreri C, Kaiser N, Sasson S. Beta cell response to nutrient overload involves phospholipid remodelling and lipid peroxidation. Diabetologia 2015; 58:1333-43. [PMID: 25810039 DOI: 10.1007/s00125-015-3566-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 03/11/2015] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS Membrane phospholipids are the major intracellular source for fatty acid-derived mediators, which regulate myriad cell functions. We showed previously that high glucose levels triggered the hydrolysis of polyunsaturated fatty acids from beta cell phospholipids. These fatty acids were subjected to free radical-catalysed peroxidation to generate the bioactive aldehyde 4-hydroxy-2E-nonenal (4-HNE). The latter activated the nuclear peroxisome proliferator-activated receptor-δ (PPARδ), which in turn augmented glucose-stimulated insulin secretion. The present study aimed at investigating the combined effects of glucose and fatty acid overload on phospholipid turnover and the subsequent generation of lipid mediators, which affect insulin secretion and beta cell viability. METHODS INS-1E cells were incubated with increasing glucose concentrations (5-25 mmol/l) without or with palmitic acid (PA; 50-500 μmol/l) and taken for fatty acid-based lipidomic analysis and functional assays. Rat isolated islets of Langerhans were used similarly. RESULTS PA was incorporated into membrane phospholipids in a concentration- and time-dependent manner; incorporation was highest at 25 mmol/l glucose. This was coupled to a rapid exchange with saturated, mono-unsaturated and polyunsaturated fatty acids. Importantly, released arachidonic acid and linoleic acid were subjected to peroxidation, resulting in the generation of 4-HNE, which further augmented insulin secretion by activating PPARδ in beta cells. However, this adaptive increase in insulin secretion was abolished at high glucose and PA levels, which induced endoplasmic reticulum stress, apoptosis and cell death. CONCLUSIONS/INTERPRETATION These findings highlight a key role for phospholipid remodelling and fatty acid peroxidation in mediating adaptive and cytotoxic interactions induced by nutrient overload in beta cells.
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Affiliation(s)
- Guy Cohen
- Department of Pharmacology, Institute for Drug Research, Faculty of Medicine, The Hebrew University, Jerusalem, 9112102, Israel
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Oliveira AF, Cunha DA, Ladriere L, Igoillo-Esteve M, Bugliani M, Marchetti P, Cnop M. In vitro use of free fatty acids bound to albumin: A comparison of protocols. Biotechniques 2015; 58:228-33. [PMID: 25967901 DOI: 10.2144/000114285] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/02/2015] [Indexed: 11/23/2022] Open
Affiliation(s)
- Ana F Oliveira
- ULB Center for Diabetes Research, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Daniel A Cunha
- ULB Center for Diabetes Research, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Laurence Ladriere
- ULB Center for Diabetes Research, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Mariana Igoillo-Esteve
- ULB Center for Diabetes Research, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Marco Bugliani
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
| | - Piero Marchetti
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
| | - Miriam Cnop
- ULB Center for Diabetes Research, Université Libre de Bruxelles (ULB), Brussels, Belgium.,Division of Endocrinology, Erasmus Hospital, Brussels, Belgium
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44
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Odisho T, Zhang L, Volchuk A. ATF6β regulates the Wfs1 gene and has a cell survival role in the ER stress response in pancreatic β-cells. Exp Cell Res 2014; 330:111-22. [PMID: 25447309 DOI: 10.1016/j.yexcr.2014.10.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 10/02/2014] [Accepted: 10/05/2014] [Indexed: 01/20/2023]
Abstract
Endoplasmic reticulum (ER) stress is implicated in pancreatic β-cell dysfunction and death resulting in type 2 diabetes. Activating transcription factor 6 (ATF6) is an essential component of the Unfolded Protein Response (UPR) and consists of two isoforms, ATF6α and ATF6β. Here we investigated the role of ATF6β. ATF6β mRNA was detected in pancreatic β-cell lines and rodent and human islets. We also detected ATF6β protein and production of the active form (ATF6βp60) in response to ER stress. Knock-down of ATF6β in INS-1 832/13 insulinoma cells did not affect mRNA induction of several major UPR genes in response to ER stress, suggesting ATF6β is not essential for the basic UPR. Expressing active ATF6βp60 or ATF6αp50 followed by microarray analysis showed that they regulate similar UPR genes, although some genes such as Wfs1 are ATF6β-specific. ATF6β, but not ATF6α, is able to bind the Wfs1 promoter and induce Wfs1 gene and protein expression. Knock-down of ATF6β increased the susceptibility of β-cells to ER stress-induced apoptosis, while overexpression of active ATF6βp60 reduced apoptosis. Thus, ATF6β is not essential for induction of most UPR genes, but is required to maintain cell survival in β-cells undergoing chronic ER stress, which in part relates to its ability to induce Wfs1, a pro-survival gene.
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Affiliation(s)
- Tanya Odisho
- Division of Advanced Diagnostics - Metabolism, Toronto General Research Institute, University Health Network, Canada; Department of Physiology, University of Toronto, Canada
| | - Liling Zhang
- Division of Advanced Diagnostics - Metabolism, Toronto General Research Institute, University Health Network, Canada
| | - Allen Volchuk
- Division of Advanced Diagnostics - Metabolism, Toronto General Research Institute, University Health Network, Canada; Department of Physiology, University of Toronto, Canada; Department of Biochemistry, University of Toronto, Canada.
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45
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46
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Hayashi H, Yamada R, Das SS, Sato T, Takahashi A, Hiratsuka M, Hirasawa N. Glucagon-like peptide-1 production in the GLUTag cell line is impaired by free fatty acids via endoplasmic reticulum stress. Metabolism 2014; 63:800-11. [PMID: 24680601 DOI: 10.1016/j.metabol.2014.02.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 02/15/2014] [Accepted: 02/17/2014] [Indexed: 12/16/2022]
Abstract
OBJECTS Glucagon-like peptide-1 (GLP-1) is secreted from intestinal L cells, enhances glucose-stimulated insulin secretion, and protects pancreas beta cells. However, few studies have examined hypernutrition stress in L cells and its effects on their function. Here, we demonstrated that a high-fat diet reduced glucose-stimulated secretion of GLP-1 and induced expression of an endoplasmic reticulum (ER) stress markers in the intestine of a diet-induced obesity mouse model. METHODS To clarify whether ER stress in L cells caused the attenuation of GLP-1 secretion, we treated the mouse intestinal L cell line, GLUTag cells with palmitate or oleate. RESULTS Palmitate, but not oleate caused ER stress and decreased the protein levels of prohormone convertase 1/3 (PC1/3), an essential enzyme in GLP-1 production. The same phenomena were observed in GLUTag cells treated with in ER stress inducer, thapsigargin. Moreover, oleate improved palmitate-induced ER stress, reduced protein and activity levels of PC1/3, and attenuated GLP-1 secretion from GLUTag cells. CONCLUSIONS/INTERPRETATION These results suggest that the intake of abundant saturated fatty acids induces ER stress in the intestine and decreases GLP-1 production.
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Affiliation(s)
- Hiroto Hayashi
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Ren Yamada
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Siddhartha Shankar Das
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Taiki Sato
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Aki Takahashi
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Masahiro Hiratsuka
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Noriyasu Hirasawa
- Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan.
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47
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Huang S, Zhu M, Wu W, Rashid A, Liang Y, Hou L, Ning Q, Luo X. Valproate pretreatment protects pancreatic β-cells from palmitate-induced ER stress and apoptosis by inhibiting glycogen synthase kinase-3β. J Biomed Sci 2014; 21:38. [PMID: 24884462 PMCID: PMC4084580 DOI: 10.1186/1423-0127-21-38] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 04/29/2014] [Indexed: 01/09/2023] Open
Abstract
Background Reduction of pancreatic β-cells mass, major secondary to increased β-cells apoptosis, is increasingly recognized as one of the main contributing factors to the pathogenesis of type 2 diabetes (T2D), and saturated free fatty acid palmitate has been shown to induce endoplasmic reticulum (ER) stress that may contribute to promoting β-cells apoptosis. Recent literature suggests that valproate, a diffusely prescribed drug in the treatment of epilepsy and bipolar disorder, can inhibit glycogen synthase kinase-3β (GSK-3β) activity and has cytoprotective effects in neuronal cells and HepG2 cells. Thus, we hypothesized that valproate may protect INS-1 β-cells from palmitate-induced apoptosis via inhibiting GSK-3β. Results Valproate pretreatment remarkable prevented palmitate-mediated cytotoxicity and apoptosis (lipotoxicity) as well as ER distension. Furthermore, palmitate triggered ER stress as evidenced by increased mRNA levels of C/EBP homologous protein (CHOP) and activating transcription factor 4 (ATF4) in a time-dependent fashion. However, valproate not only reduced the mRNA and protein expression of CHOP but also inhibited GSK-3β and caspase-3 activity induced by palmitate, whereas, the mRNA expression of ATF4 was not affected. Interestingly, TDZD-8, a specific GSK-3β inhibitor, also showed the similar effect on lipotoxicity and ER stress as valproate in INS-1 cells. Finally, compared with CHOP knockdown, valproate displayed better cytoprotection against palmitate. Conclusions Valproate may protect β-cells from palmitate-induced apoptosis and ER stress via GSK-3β inhibition, independent of ATF4/CHOP pathway. Besides, GSK-3β, rather than CHOP, may be a more promising therapeutic target for T2D.
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Affiliation(s)
| | | | | | | | | | | | | | - Xiaoping Luo
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, No,1095, Jiefang Avenue, Wuhan, Hubei Province 430030, P,R, China.
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48
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Song H, Wohltmann M, Tan M, Ladenson JH, Turk J. Group VIA phospholipase A2 mitigates palmitate-induced β-cell mitochondrial injury and apoptosis. J Biol Chem 2014; 289:14194-210. [PMID: 24648512 DOI: 10.1074/jbc.m114.561910] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Palmitate (C16:0) induces apoptosis of insulin-secreting β-cells by processes that involve generation of reactive oxygen species, and chronically elevated blood long chain free fatty acid levels are thought to contribute to β-cell lipotoxicity and the development of diabetes mellitus. Group VIA phospholipase A2 (iPLA2β) affects β-cell sensitivity to apoptosis, and here we examined iPLA2β effects on events that occur in β-cells incubated with C16:0. Such events in INS-1 insulinoma cells were found to include activation of caspase-3, expression of stress response genes (C/EBP homologous protein and activating transcription factor 4), accumulation of ceramide, loss of mitochondrial membrane potential, and apoptosis. All of these responses were blunted in INS-1 cells that overexpress iPLA2β, which has been proposed to facilitate repair of oxidized mitochondrial phospholipids, e.g. cardiolipin (CL), by excising oxidized polyunsaturated fatty acid residues, e.g. linoleate (C18:2), to yield lysophospholipids, e.g. monolysocardiolipin (MLCL), that can be reacylated to regenerate the native phospholipid structures. Here the MLCL content of mouse pancreatic islets was found to rise with increasing iPLA2β expression, and recombinant iPLA2β hydrolyzed CL to MLCL and released oxygenated C18:2 residues from oxidized CL in preference to native C18:2. C16:0 induced accumulation of oxidized CL species and of the oxidized phospholipid (C18:0/hydroxyeicosatetraenoic acid)-glycerophosphoethanolamine, and these effects were blunted in INS-1 cells that overexpress iPLA2β, consistent with iPLA2β-mediated removal of oxidized phospholipids. C16:0 also induced iPLA2β association with INS-1 cell mitochondria, consistent with a role in mitochondrial repair. These findings indicate that iPLA2β confers significant protection of β-cells against C16:0-induced injury.
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Affiliation(s)
- Haowei Song
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Mary Wohltmann
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Min Tan
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
| | - Jack H Ladenson
- Division of Laboratory and Genomic Medicine, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - John Turk
- From the Mass Spectrometry Resource, Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine and
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49
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Lee JH, Jung IR, Choi SE, Lee SM, Lee SJ, Han SJ, Kim HJ, Kim DJ, Lee KW, Kang Y. Toxicity generated through inhibition of pyruvate carboxylase and carnitine palmitoyl transferase-1 is similar to high glucose/palmitate-induced glucolipotoxicity in INS-1 beta cells. Mol Cell Endocrinol 2014; 383:48-59. [PMID: 24333689 DOI: 10.1016/j.mce.2013.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 11/14/2013] [Accepted: 12/01/2013] [Indexed: 01/22/2023]
Abstract
This work was initiated to determine whether toxicity generated through inhibition of mitochondrial fuel metabolism is similar to high glucose/palmitate (HG/PA)-induced glucolipotoxicity. Influx of glucose and free fatty acids into the tricarboxylic acid (TCA) cycle was inhibited by treatment with the pyruvate carboxylase (PC) inhibitor phenylacetic acid (PAA) and carnitine palmitoyl transferase-1 (CPT-1) inhibitor etomoxir (Eto), or knockdown of PC and CPT-1. Treatment of PAA/Eto or knockdown of PC/CPT-1 induced apoptotic death in INS-1 beta cells. Similar to HG/PA treatment, PAA/Eto increased endoplasmic reticulum stress responses but decreased the Akt signal. JNK inhibitor or chemical chaperone was protective against both PAA/Eto- and HG/PA-induced cell death. All attempts to reduce [Ca²⁺](i), stimulate lipid metabolism, and increase the TCA cycle intermediate pool protected PAA/Eto-induced death as well as HG/PA-induced death. These data suggest that signals induced from impaired mitochondrial fuel metabolism play a critical role in HG/PA-induced glucolipotoxicity.
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Affiliation(s)
- Ji-Hyun Lee
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea; Department of Life Science, Korea University Seoul 136-701, Republic of Korea
| | - Ik-Rak Jung
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Sung-E Choi
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Sung-Mi Lee
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Soo-Jin Lee
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Seung Jin Han
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Hae Jin Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Dae Jung Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Kwan-Woo Lee
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Yup Kang
- Department of physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea.
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50
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Hara T, Mahadevan J, Kanekura K, Hara M, Lu S, Urano F. Calcium efflux from the endoplasmic reticulum leads to β-cell death. Endocrinology 2014; 155:758-68. [PMID: 24424032 PMCID: PMC3929724 DOI: 10.1210/en.2013-1519] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
It has been established that intracellular calcium homeostasis is critical for survival and function of pancreatic β-cells. However, the role of endoplasmic reticulum (ER) calcium homeostasis in β-cell survival and death is not clear. Here we show that ER calcium depletion plays a critical role in β-cell death. Various pathological conditions associated with β-cell death, including ER stress, oxidative stress, palmitate, and chronic high glucose, decreased ER calcium levels and sarcoendoplasmic reticulum Ca(2+)-ATPase 2b expression, leading to β-cell death. Ectopic expression of mutant insulin and genetic ablation of WFS1, a causative gene for Wolfram syndrome, also decreased ER calcium levels and induced β-cell death. Hyperactivation of calpain-2, a calcium-dependent proapoptotic protease, was detected in β-cells undergoing ER calcium depletion. Ectopic expression of sarcoendoplasmic reticulum Ca(2+)-ATPase 2b, as well as pioglitazone and rapamycin treatment, could prevent calcium efflux from the ER and mitigate β-cell death under various stress conditions. Our results reveal a critical role of ER calcium depletion in β-cell death and indicate that identification of pathways and chemical compounds restoring ER calcium levels will lead to novel therapeutic modalities and pharmacological interventions for type 1 and type 2 diabetes and other ER-related diseases including Wolfram syndrome.
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Affiliation(s)
- Takashi Hara
- Department of Medicine (T.H., J.M., K.K., M.H., S.L., F.U.), Division of Endocrinology, Metabolism, and Lipid Research, and Department of Pathology and Immunology (F.U.), Washington University School of Medicine, St Louis, Missouri 63110; and Cardiovascular-Metabolics Research Laboratories (T.H.), Daiichi Sankyo Co, Ltd, Tokyo 103-8426, Japan
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