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Jevon D, Cottle L, Hallahan N, Harwood R, Samra JS, Gill AJ, Loudovaris T, Thomas HE, Thorn P. Capillary contact points determine beta cell polarity, control secretion and are disrupted in the db/db mouse model of diabetes. Diabetologia 2024:10.1007/s00125-024-06180-x. [PMID: 38814445 DOI: 10.1007/s00125-024-06180-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 03/26/2024] [Indexed: 05/31/2024]
Abstract
AIMS/HYPOTHESIS Almost all beta cells contact one capillary and insulin granule fusion is targeted to this region. However, there are reports of beta cells contacting more than one capillary. We therefore set out to determine the proportion of beta cells with multiple contacts and the impact of this on cell structure and function. METHODS We used pancreatic slices in mice and humans to better maintain cell and islet structure than in isolated islets. Cell structure was assayed using immunofluorescence and 3D confocal microscopy. Live-cell two-photon microscopy was used to map granule fusion events in response to glucose stimulation. RESULTS We found that 36% and 22% of beta cells in islets from mice and humans, respectively, have separate contact with two capillaries. These contacts establish a distinct form of cell polarity with multiple basal regions. Both capillary contact points are enriched in presynaptic scaffold proteins, and both are a target for insulin granule fusion. Cells with two capillary contact points have a greater capillary contact area and secrete more, with analysis showing that, independent of the number of contact points, increased contact area is correlated with increased granule fusion. Using db/db mice as a model for type 2 diabetes, we observed changes in islet capillary organisation that significantly reduced total islet capillary surface area, and reduced area of capillary contact in single beta cells. CONCLUSIONS/INTERPRETATION Beta cells that contact two capillaries are a significant subpopulation of beta cells within the islet. They have a distinct form of cell polarity and both contact points are specialised for secretion. The larger capillary contact area of cells with two contact points is correlated with increased secretion. In the db/db mouse, changes in capillary structure impact beta cell capillary contact, implying that this is a new factor contributing to disease progression.
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Affiliation(s)
- Dillon Jevon
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Louise Cottle
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Nicole Hallahan
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Richard Harwood
- Charles Perkins Centre, Sydney Microscopy and Microanalysis, University of Sydney, Camperdown, NSW, Australia
| | - Jaswinder S Samra
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Anthony J Gill
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Department of Anatomical Pathology, Royal North Shore Hospital, St Leonards, NSW, Australia
- Cancer Diagnosis and Pathology Research Group, Kolling Institute of Medical Research, St Leonards, NSW, Australia
| | | | - Helen E Thomas
- St Vincent's Institute, Fitzroy, VIC, Australia
- Department of Medicine, St Vincent's Hospital, University of Melbourne, Fitzroy, VIC, Australia
| | - Peter Thorn
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia.
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2
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Li W, Li A, Yu B, Zhang X, Liu X, White KL, Stevens RC, Baumeister W, Sali A, Jasnin M, Sun L. In situ structure of actin remodeling during glucose-stimulated insulin secretion using cryo-electron tomography. Nat Commun 2024; 15:1311. [PMID: 38346988 PMCID: PMC10861521 DOI: 10.1038/s41467-024-45648-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 01/30/2024] [Indexed: 02/15/2024] Open
Abstract
Actin mediates insulin secretion in pancreatic β-cells through remodeling. Hampered by limited resolution, previous studies have offered an ambiguous depiction as depolymerization and repolymerization. We report the in situ structure of actin remodeling in INS-1E β-cells during glucose-stimulated insulin secretion at nanoscale resolution. After remodeling, the actin filament network at the cell periphery exhibits three marked differences: 12% of actin filaments reorient quasi-orthogonally to the ventral membrane; the filament network mainly remains as cell-stabilizing bundles but partially reconfigures into a less compact arrangement; actin filaments anchored to the ventral membrane reorganize from a "netlike" to a "blooming" architecture. Furthermore, the density of actin filaments and microtubules around insulin secretory granules decreases, while actin filaments and microtubules become more densely packed. The actin filament network after remodeling potentially precedes the transport and release of insulin secretory granules. These findings advance our understanding of actin remodeling and its role in glucose-stimulated insulin secretion.
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Affiliation(s)
- Weimin Li
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Angdi Li
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Bing Yu
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Xiaoxiao Zhang
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
| | - Xiaoyan Liu
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
| | - Kate L White
- Department of Chemistry, Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, 90089, USA
| | - Raymond C Stevens
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Wolfgang Baumeister
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany.
| | - Andrej Sali
- Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA, 94158, USA.
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, 94158, USA.
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, 94158, USA.
| | - Marion Jasnin
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
- Department of Chemistry, Technical University of Munich, 85748, Garching, Germany.
| | - Liping Sun
- iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.
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3
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Fye MA, Kaverina I. Insulin secretion hot spots in pancreatic β cells as secreting adhesions. Front Cell Dev Biol 2023; 11:1211482. [PMID: 37305687 PMCID: PMC10250740 DOI: 10.3389/fcell.2023.1211482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/18/2023] [Indexed: 06/13/2023] Open
Abstract
Pancreatic β cell secretion of insulin is crucial to the maintenance of glucose homeostasis and prevention of diseases related to glucose regulation, including diabetes. Pancreatic β cells accomplish efficient insulin secretion by clustering secretion events at the cell membrane facing the vasculature. Regions at the cell periphery characterized by clustered secretion are currently termed insulin secretion hot spots. Several proteins, many associated with the microtubule and actin cytoskeletons, are known to localize to and serve specific functions at hot spots. Among these proteins are the scaffolding protein ELKS, the membrane-associated proteins LL5β and liprins, the focal adhesion-associated protein KANK1, and other factors typically associated with the presynaptic active zone in neurons. These hot spot proteins have been shown to contribute to insulin secretion, but many questions remain regarding their organization and dynamics at hot spots. Current studies suggest microtubule- and F-actin are involved in regulation of hot spot proteins and their function in secretion. The hot spot protein association with the cytoskeleton networks also suggests a potential role for mechanical regulation of these proteins and hot spots in general. This perspective summarizes the existing knowledge of known hot spot proteins, their cytoskeletal-mediated regulation, and discuss questions remaining regarding mechanical regulation of pancreatic beta cell hot spots.
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Affiliation(s)
| | - Irina Kaverina
- Kaverina Lab, Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, United States
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4
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Ruiz-Otero N, Kuruvilla R. Role of Delta/Notch-like EGF-related receptor in blood glucose homeostasis. Front Endocrinol (Lausanne) 2023; 14:1161085. [PMID: 37223028 PMCID: PMC10200888 DOI: 10.3389/fendo.2023.1161085] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 04/18/2023] [Indexed: 05/25/2023] Open
Abstract
Cell-cell interactions are necessary for optimal endocrine functions in the pancreas. β-cells, characterized by the expression and secretion of the hormone insulin, are a major constituent of functional micro-organs in the pancreas known as islets of Langerhans. Cell-cell contacts between β-cells are required to regulate insulin production and glucose-stimulated insulin secretion, which are key determinants of blood glucose homeostasis. Contact-dependent interactions between β-cells are mediated by gap junctions and cell adhesion molecules such as E-cadherin and N-CAM. Recent genome-wide studies have implicated Delta/Notch-like EGF-related receptor (Dner) as a potential susceptibility locus for Type 2 Diabetes in humans. DNER is a transmembrane protein and a proposed Notch ligand. DNER has been implicated in neuron-glia development and cell-cell interactions. Studies herein demonstrate that DNER is expressed in β-cells with an onset during early postnatal life and sustained throughout adulthood in mice. DNER loss in adult β-cells in mice (β-Dner cKO mice) disrupted islet architecture and decreased the expression of N-CAM and E-cadherin. β-Dner cKO mice also exhibited impaired glucose tolerance, defects in glucose- and KCl-induced insulin secretion, and decreased insulin sensitivity. Together, these studies suggest that DNER plays a crucial role in mediating islet cell-cell interactions and glucose homeostasis.
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Affiliation(s)
- Nelmari Ruiz-Otero
- Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Rejji Kuruvilla
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
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5
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Fu L, Wang X, Yang Y, Chen M, Kuerban A, Liu H, Dong Y, Cai Q, Ma M, Wu X. Septin11 promotes hepatocellular carcinoma cell motility by activating RhoA to regulate cytoskeleton and cell adhesion. Cell Death Dis 2023; 14:280. [PMID: 37080972 PMCID: PMC10119145 DOI: 10.1038/s41419-023-05726-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 02/25/2023] [Accepted: 03/09/2023] [Indexed: 04/22/2023]
Abstract
Septins as GTPases in the cytoskeleton, are linked to a broad spectrum of cellular functions, including cell migration and the progression of hepatocellular carcinoma (HCC). However, roles of SEPT11, the new member of septin, have been hardly understood in HCC. In the study, the clinical significance and biological function of SEPT11 in HCC was explored. SEPT11 was screened out by combining ATAC-seq with mRNA-seq. Role of SEPT11 in HCC was further investigated by using overexpression, shRNA and CRISPR/Cas9-mediated SEPT11-knockout cells or in vivo models. We found RNA-seq and ATAC-seq highlights LncRNA AY927503 (AY) induced SEPT11 transcription, resulting in Rho GTPase activation and cytoskeleton actin aggregation. The GTP-binding protein SEPT11 is thus considered, as a downstream factor of AY, highly expressed in various tumors, including HCC, and associated with poor prognosis of the patients. In vitro, SEPT11 overexpression promotes the migration and invasion of HCC cells, while SEPT11-knockout inhibits migration and invasion. In vivo, SEPT11-overexpressed HCC cells show high metastasis incidents but don't significantly affect proliferation. Meanwhile, we found SEPT11 targets RhoA, thereby regulating cytoskeleton rearrangement and abnormal cell adhesion through ROCK1/cofilin and FAK/paxillin signaling pathways, promoting invasion and migration of HCC. Further, we found SEPT11 facilitates the binding of GEF-H1 to RhoA, which enhances the activity of RhoA. Overall, our study confirmed function of SEPT11 in promoting metastasis in HCC, and preliminarily explored its related molecular mechanism. SEPT11 acts as an oncogene in HCC, also draws further interest regarding its clinical application as a potential therapeutic target.
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Affiliation(s)
- Lisheng Fu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, and Department of Cardiology of Huadong Hospital Affiliated to Fudan University, Fudan University, 200032, Shanghai, People's Republic of China
| | - Xiaoyan Wang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Microbiology and Parasitology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, 200032, Shanghai, People's Republic of China
| | - Ying Yang
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, and Department of Cardiology of Huadong Hospital Affiliated to Fudan University, Fudan University, 200032, Shanghai, People's Republic of China
| | - MeiHua Chen
- NHC Key Laboratory of Glycoconjugates, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, 200032, Shanghai, People's Republic of China
| | - Adilijiang Kuerban
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University, Fudan University, 200040, Shanghai, People's Republic of China
| | - Haojie Liu
- NHC Key Laboratory of Glycoconjugates, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, 200032, Shanghai, People's Republic of China
| | - Yiwei Dong
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, and Department of Cardiology of Huadong Hospital Affiliated to Fudan University, Fudan University, 200032, Shanghai, People's Republic of China
| | - QianQian Cai
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, and Department of Cardiology of Huadong Hospital Affiliated to Fudan University, Fudan University, 200032, Shanghai, People's Republic of China.
- Shanghai Key Laboratory of Molecular Imaging, Shanghai University of Medicine and Health Sciences, 201318, Shanghai, China.
| | - Mingzhe Ma
- Department of Gastric Surgery, Shanghai Cancer Center of Fudan University, 200032, Shanghai, People's Republic of China.
| | - XingZhong Wu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, and Department of Cardiology of Huadong Hospital Affiliated to Fudan University, Fudan University, 200032, Shanghai, People's Republic of China.
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Barillaro M, Schuurman M, Wang R. β1-Integrin-A Key Player in Controlling Pancreatic Beta-Cell Insulin Secretion via Interplay With SNARE Proteins. Endocrinology 2022; 164:6772824. [PMID: 36282882 DOI: 10.1210/endocr/bqac179] [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: 08/26/2022] [Indexed: 01/16/2023]
Abstract
Shortcomings in cell-based therapies for patients with diabetes have been revealed to be, in part, a result of an improper extracellular matrix (ECM) environment. In vivo, pancreatic islets are emersed in a diverse ECM that provides physical support and is crucial for healthy function. β1-Integrin receptors have been determined to be responsible for modulation of beneficial interactions with ECM proteins influencing beta-cell development, proliferation, maturation, and function. β1-Integrin signaling has been demonstrated to augment insulin secretion by impacting the actin cytoskeleton via activation of focal adhesion kinase and downstream signaling pathways. In other secretory cells, evidence of a bidirectional relationship between integrins and exocytotic machinery has been demonstrated, and, thus, this relationship could be present in pancreatic beta cells. In this review, we will discuss the role of ECM-β1-integrin interplay with exocytotic proteins in controlling pancreatic beta-cell insulin secretion through their dynamic and unique signaling pathway.
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Affiliation(s)
- Malina Barillaro
- Children's Health Research Institute, University of Western Ontario, London, ON N6C 2V5, Canada
- Department of Physiology & Pharmacology, University of Western Ontario, London, ON N6C 2V5, Canada
| | - Meg Schuurman
- Children's Health Research Institute, University of Western Ontario, London, ON N6C 2V5, Canada
- Department of Physiology & Pharmacology, University of Western Ontario, London, ON N6C 2V5, Canada
| | - Rennian Wang
- Children's Health Research Institute, University of Western Ontario, London, ON N6C 2V5, Canada
- Department of Physiology & Pharmacology, University of Western Ontario, London, ON N6C 2V5, Canada
- Department of Medicine, University of Western Ontario, London, ON N6C 2V5, Canada
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7
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Yang L, Fye MA, Yang B, Tang Z, Zhang Y, Haigh S, Covington BA, Bracey K, Taraska JW, Kaverina I, Qu S, Chen W. Genome-wide CRISPR screen identified a role for commander complex mediated ITGB1 recycling in basal insulin secretion. Mol Metab 2022; 63:101541. [PMID: 35835371 PMCID: PMC9304790 DOI: 10.1016/j.molmet.2022.101541] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/30/2022] [Accepted: 07/01/2022] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVES Pancreatic beta cells secrete insulin postprandially and during fasting to maintain glucose homeostasis. Although glucose-stimulated insulin secretion (GSIS) has been extensively studied, much less is known about basal insulin secretion. Here, we performed a genome-wide CRISPR/Cas9 knockout screen to identify novel regulators of insulin secretion. METHODS To identify genes that cell autonomously regulate insulin secretion, we engineered a Cas9-expressing MIN6 subclone that permits irreversible fluorescence labeling of exocytic insulin granules. Using a fluorescence-activated cell sorting assay of exocytosis in low glucose and high glucose conditions in individual cells, we performed a genome-wide CRISPR/Cas9 knockout screen. RESULTS We identified several members of the COMMD family, a conserved family of proteins with central roles in intracellular membrane trafficking, as positive regulators of basal insulin secretion, but not GSIS. Mechanistically, we show that the Commander complex promotes insulin granules docking in basal state. This is mediated, at least in part, by its function in ITGB1 recycling. Defective ITGB1 recycling reduces its membrane distribution, the number of focal adhesions and cortical ELKS-containing complexes. CONCLUSIONS We demonstrated a previously unknown function of the Commander complex in basal insulin secretion. We showed that by ITGB1 recycling, Commander complex increases cortical adhesions, which enhances the assembly of the ELKS-containing complexes. The resulting increase in the number of insulin granules near the plasma membrane strengthens basal insulin secretion.
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Affiliation(s)
- Liu Yang
- Department of Endocrinology and Metabolism, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200072, China; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Margret A Fye
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Bingyuan Yang
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Zihan Tang
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Yue Zhang
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Sander Haigh
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Brittney A Covington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Kai Bracey
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Justin W Taraska
- Biochemistry and Biophysics Center, NHLBI, NIH, Bethesda, MD 20892, USA
| | - Irina Kaverina
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Shen Qu
- Department of Endocrinology and Metabolism, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200072, China.
| | - Wenbiao Chen
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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8
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Islam R, Mishra J, Bodas S, Bhattacharya S, Batra SK, Dutta S, Datta K. Role of Neuropilin-2-mediated signaling axis in cancer progression and therapy resistance. Cancer Metastasis Rev 2022; 41:771-787. [PMID: 35776228 PMCID: PMC9247951 DOI: 10.1007/s10555-022-10048-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 06/16/2022] [Indexed: 12/12/2022]
Abstract
Neuropilins (NRPs) are transmembrane proteins involved in vascular and nervous system development by regulating angiogenesis and axon guidance cues. Several published reports have established their role in tumorigenesis. NRPs are detectable in tumor cells of several cancer types and participate in cancer progression. NRP2 is also expressed in endothelial and immune cells in the tumor microenvironment and promotes functions such as lymphangiogenesis and immune suppression important for cancer progression. In this review, we have taken a comprehensive approach to discussing various aspects of NRP2-signaling in cancer, including its regulation, functional significance in cancer progression, and how we could utilize our current knowledge to advance the studies and target NRP2 to develop effective cancer therapies.
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Affiliation(s)
- Ridwan Islam
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Juhi Mishra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Sanika Bodas
- Department of Molecular Genetics and Cell Biology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Sreyashi Bhattacharya
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Surinder K Batra
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Samikshan Dutta
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
| | - Kaustubh Datta
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
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9
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Jevon D, Deng K, Hallahan N, Kumar K, Tong J, Gan WJ, Tran C, Bilek MM, Thorn P. Local activation of focal adhesion kinase orchestrates the positioning of presynaptic scaffold proteins and Ca 2+ signalling to control glucose dependent insulin secretion. eLife 2022; 11:76262. [PMID: 35559734 PMCID: PMC9126582 DOI: 10.7554/elife.76262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
A developing understanding suggests that spatial compartmentalisation in pancreatic β cells is critical in controlling insulin secretion. To investigate the mechanisms, we have developed live-cell sub-cellular imaging methods using the mouse organotypic pancreatic slice. We demonstrate that the organotypic pancreatic slice, when compared with isolated islets, preserves intact β cell structure, and enhances glucose dependent Ca2+ responses and insulin secretion. Using the slice technique, we have discovered the essential role of local activation of integrins and the downstream component, focal adhesion kinase, in regulating β cells. Integrins and focal adhesion kinase are exclusively activated at the β cell capillary interface and using in situ and in vitro models we show their activation both positions presynaptic scaffold proteins, like ELKS and liprin, and regulates glucose dependent Ca2+ responses and insulin secretion. We conclude that focal adhesion kinase orchestrates the final steps of glucose dependent insulin secretion within the restricted domain where β cells contact the islet capillaries.
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Affiliation(s)
- Dillon Jevon
- School of Medical Sciences, University of Sydney, Sydney, Australia
| | - Kylie Deng
- School of Medical Sciences, University of Sydney, Sydney, Australia
| | - Nicole Hallahan
- School of Medical Sciences, University of Sydney, Sydney, Australia
| | - Krish Kumar
- School of Medical Sciences, University of Sydney, Sydney, Australia
| | - Jason Tong
- School of Medical Sciences, University of Sydney, Sydney, Australia
| | - Wan Jun Gan
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Clara Tran
- School of Physics, University of Sydney, Sydney, Australia
| | | | - Peter Thorn
- School of Medical Sciences, University of Sydney, Sydney, Australia
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10
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Noordstra I, van den Berg CM, Boot FWJ, Katrukha EA, Yu KL, Tas RP, Portegies S, Viergever BJ, de Graaff E, Hoogenraad CC, de Koning EJP, Carlotti F, Kapitein LC, Akhmanova A. Organization and dynamics of the cortical complexes controlling insulin secretion in β-cells. J Cell Sci 2022; 135:274234. [PMID: 35006275 PMCID: PMC8918791 DOI: 10.1242/jcs.259430] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/21/2021] [Indexed: 11/20/2022] Open
Abstract
Insulin secretion in pancreatic β-cells is regulated by cortical complexes that are enriched at the sites of adhesion to extracellular matrix facing the vasculature. Many components of these complexes, including bassoon, RIM, ELKS and liprins, are shared with neuronal synapses. Here, we show that insulin secretion sites also contain the non-neuronal proteins LL5β (also known as PHLDB2) and KANK1, which, in migrating cells, organize exocytotic machinery in the vicinity of integrin-based adhesions. Depletion of LL5β or focal adhesion disassembly triggered by myosin II inhibition perturbed the clustering of secretory complexes and attenuated the first wave of insulin release. Although previous analyses in vitro and in neurons have suggested that secretory machinery might assemble through liquid–liquid phase separation, analysis of endogenously labeled ELKS in pancreatic islets indicated that its dynamics is inconsistent with such a scenario. Instead, fluorescence recovery after photobleaching and single-molecule imaging showed that ELKS turnover is driven by binding and unbinding to low-mobility scaffolds. Both the scaffold movements and ELKS exchange were stimulated by glucose treatment. Our findings help to explain how integrin-based adhesions control spatial organization of glucose-stimulated insulin release. Summary: Characterization of the composition of cortical complexes controlling insulin secretion, showing that their dynamics is inconsistent with assembly through liquid–liquid phase separation.
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Affiliation(s)
- Ivar Noordstra
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Division of Cell and Developmental Biology, Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Cyntha M van den Berg
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Fransje W J Boot
- Department of Internal Medicine, Nephrology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Eugene A Katrukha
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Ka Lou Yu
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Roderick P Tas
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Sybren Portegies
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Bastiaan J Viergever
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Esther de Graaff
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Casper C Hoogenraad
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Eelco J P de Koning
- Department of Internal Medicine, Nephrology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Françoise Carlotti
- Department of Internal Medicine, Nephrology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
| | - Lukas C Kapitein
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Anna Akhmanova
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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11
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Wang X, Gao M, Wang Y, Zhang Y. The progress of pluripotent stem cell-derived pancreatic β-cells regeneration for diabetic therapy. Front Endocrinol (Lausanne) 2022; 13:927324. [PMID: 35966093 PMCID: PMC9365963 DOI: 10.3389/fendo.2022.927324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 06/27/2022] [Indexed: 11/13/2022] Open
Abstract
Diabetes is a complex metabolic disorder of carbohydrate metabolism, characterized by high blood glucose levels either due to an absolute deficiency of insulin secretion or an ineffective response of cells to insulin, a hormone synthetized by β-cells in the pancreas. Despite the current substantial progress of new drugs and strategies to prevent and treat diabetes, we do not understand precisely the exact cause of the failure and impairment of β-cells. Therefore, there is an urgent need to find new methods to restore β-cells. In recent years, pluripotent stem cells (PSCs) such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSC) can serve as an ideal alternative source for the pancreatic β-cells. In this review, we systematically summarize the current progress and protocols of generating pancreatic β-cells from human PSCs. Meanwhile, we also discuss some challenges and future perspectives of human PSCs treatments for diabetes.
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Affiliation(s)
- Xin Wang
- China-Japan Union Hospital of Jilin University, Changchun, China
- The Third Norman Bethune Clinical College of Jilin University, Changchun, China
| | - Mengxi Gao
- China-Japan Union Hospital of Jilin University, Changchun, China
- The Third Norman Bethune Clinical College of Jilin University, Changchun, China
| | - Yali Wang
- Department of Blood Transfusion, China–Japan Union Hospital of Jilin University, Changchun, China
- *Correspondence: Yucheng Zhang, ; Yali Wang,
| | - Yucheng Zhang
- Scientific Research Center, China–Japan Union Hospital of Jilin University, Changchun, China
- *Correspondence: Yucheng Zhang, ; Yali Wang,
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12
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Karanth SS, Sun S, Bi H, Ye K, Jin S. Angiopoietins stimulate pancreatic islet development from stem cells. Sci Rep 2021; 11:13558. [PMID: 34193893 PMCID: PMC8245566 DOI: 10.1038/s41598-021-92922-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 06/09/2021] [Indexed: 12/19/2022] Open
Abstract
In vitro differentiation of human induced pluripotent stem cells (iPSCs) into functional islets holds immense potential to create an unlimited source of islets for diabetes research and treatment. A continuous challenge in this field is to generate glucose-responsive mature islets. We herein report a previously undiscovered angiopoietin signal for in vitro islet development. We revealed, for the first time, that angiopoietins, including angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2) permit the generation of islets from iPSCs with elevated glucose responsiveness, a hallmark of mature islets. Angiopoietin-stimulated islets exhibited glucose synchronized calcium ion influx in repetitive glucose challenges. Moreover, Ang2 augmented the expression of all islet hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide; and β cell transcription factors, including NKX6.1, MAFA, UCN3, and PDX1. Furthermore, we showed that the Ang2 stimulated islets were able to regulate insulin exocytosis through actin-filament polymerization and depolymerization upon glucose challenge, presumably through the CDC42-RAC1-gelsolin mediated insulin secretion signaling pathway. We also discovered the formation of endothelium within the islets under Ang2 stimulation. These results strongly suggest that angiopoietin acts as a signaling molecule to endorse in vitro islet development from iPSCs.
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Affiliation(s)
- Soujanya S Karanth
- Department of Biomedical Engineering, Binghamton University, State University of New York (SUNY), Binghamton, NY, 13902, USA
| | - Shuofei Sun
- Department of Biomedical Engineering, Binghamton University, State University of New York (SUNY), Binghamton, NY, 13902, USA
| | - Huanjing Bi
- Department of Biomedical Engineering, Binghamton University, State University of New York (SUNY), Binghamton, NY, 13902, USA
| | - Kaiming Ye
- Department of Biomedical Engineering, Binghamton University, State University of New York (SUNY), Binghamton, NY, 13902, USA.,Center of Biomanufacturing for Regenerative Medicine, Binghamton University, State University of New York (SUNY), Binghamton, NY, 13902, USA
| | - Sha Jin
- Department of Biomedical Engineering, Binghamton University, State University of New York (SUNY), Binghamton, NY, 13902, USA. .,Center of Biomanufacturing for Regenerative Medicine, Binghamton University, State University of New York (SUNY), Binghamton, NY, 13902, USA.
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13
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Cottle L, Gan WJ, Gilroy I, Samra JS, Gill AJ, Loudovaris T, Thomas HE, Hawthorne WJ, Kebede MA, Thorn P. Structural and functional polarisation of human pancreatic beta cells in islets from organ donors with and without type 2 diabetes. Diabetologia 2021; 64:618-629. [PMID: 33399909 PMCID: PMC7864831 DOI: 10.1007/s00125-020-05345-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/09/2020] [Indexed: 12/05/2022]
Abstract
AIMS/HYPOTHESIS We hypothesised that human beta cells are structurally and functional polarised with respect to the islet capillaries. We set out to test this using confocal microscopy to map the 3D spatial arrangement of key proteins and live-cell imaging to determine the distribution of insulin granule fusion around the cells. METHODS Human pancreas samples were rapidly fixed and processed using the pancreatic slice technique, which maintains islet structure and architecture. Slices were stained using immunofluorescence for polarity markers (scribble, discs large [Dlg] and partitioning defective 3 homologue [Par3]) and presynaptic markers (liprin, Rab3-interacting protein [RIM2] and piccolo) and imaged using 3D confocal microscopy. Isolated human islets were dispersed and cultured on laminin-511-coated coverslips. Live 3D two-photon microscopy was used on cultured cells to image exocytic granule fusion events upon glucose stimulation. RESULTS Assessment of the distribution of endocrine cells across human islets found that, despite distinct islet-to-islet complexity and variability, including multi-lobular islets, and intermixing of alpha and beta cells, there is still a striking enrichment of alpha cells at the islet mantle. Measures of cell position demonstrate that most beta cells contact islet capillaries. Subcellularly, beta cells consistently position polar determinants, such as Par3, Dlg and scribble, with a basal domain towards the capillaries and apical domain at the opposite face. The capillary interface/vascular face is enriched in presynaptic scaffold proteins, such as liprin, RIM2 and piccolo. Interestingly, enrichment of presynaptic scaffold proteins also occurs where the beta cells contact peri-islet capillaries, suggesting functional interactions. We also observed the same polarisation of synaptic scaffold proteins in islets from type 2 diabetic patients. Consistent with polarised function, isolated beta cells cultured onto laminin-coated coverslips target insulin granule fusion to the coverslip. CONCLUSIONS/INTERPRETATION Structural and functional polarisation is a defining feature of human pancreatic beta cells and plays an important role in the control of insulin secretion.
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Affiliation(s)
- Louise Cottle
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Wan Jun Gan
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
- Temasek Life-Science Laboratory, Singapore, Republic of Singapore
| | - Ian Gilroy
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Jaswinder S Samra
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Anthony J Gill
- The University of Sydney Northern Clinical School, Sydney, NSW, Australia
- Department of Anatomical Pathology, Royal North Shore Hospital, St Leonards, NSW, Australia
- Cancer Diagnosis and Pathology Research Group, Kolling Institute of Medical Research, St Leonards, NSW, Australia
| | | | - Helen E Thomas
- St Vincent's Institute, Fitzroy, VIC, Australia
- The University of Melbourne, Department of Medicine, St Vincent's Hospital, Fitzroy, VIC, Australia
| | - Wayne J Hawthorne
- Centre for Transplant and Renal Research, Westmead Hospital, Sydney, NSW, Australia
- Westmead Clinical School, Faculty of Health and Medicine, University of Sydney, Sydney, Australia
| | - Melkam A Kebede
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Peter Thorn
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia.
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14
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Glieberman AL, Pope BD, Melton DA, Parker KK. Building Biomimetic Potency Tests for Islet Transplantation. Diabetes 2021; 70:347-363. [PMID: 33472944 PMCID: PMC7881865 DOI: 10.2337/db20-0297] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 11/12/2020] [Indexed: 12/12/2022]
Abstract
Diabetes is a disease of insulin insufficiency, requiring many to rely on exogenous insulin with constant monitoring to avoid a fatal outcome. Islet transplantation is a recent therapy that can provide insulin independence, but the procedure is still limited by both the availability of human islets and reliable tests to assess their function. While stem cell technologies are poised to fill the shortage of transplantable cells, better methods are still needed for predicting transplantation outcome. To ensure islet quality, we propose that the next generation of islet potency tests should be biomimetic systems that match glucose stimulation dynamics and cell microenvironmental preferences and rapidly assess conditional and continuous insulin secretion with minimal manual handing. Here, we review the current approaches for islet potency testing and outline technologies and methods that can be used to arrive at a more predictive potency test that tracks islet secretory capacity in a relevant context. With the development of potency tests that can report on islet secretion dynamics in a context relevant to their intended function, islet transplantation can expand into a more widely accessible and reliable treatment option for individuals with diabetes.
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Affiliation(s)
- Aaron L Glieberman
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA
| | - Benjamin D Pope
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA
| | - Douglas A Melton
- Harvard Department of Stem Cell and Regenerative Biology, Cambridge, MA
- Harvard Stem Cell Institute, Cambridge, MA
| | - Kevin Kit Parker
- Disease Biophysics Group, Wyss Institute for Biologically Inspired Engineering, Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA
- Harvard Stem Cell Institute, Cambridge, MA
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15
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Burganova G, Bridges C, Thorn P, Landsman L. The Role of Vascular Cells in Pancreatic Beta-Cell Function. Front Endocrinol (Lausanne) 2021; 12:667170. [PMID: 33981287 PMCID: PMC8109179 DOI: 10.3389/fendo.2021.667170] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 04/08/2021] [Indexed: 12/13/2022] Open
Abstract
Insulin-producing β-cells constitute the majority of the cells in the pancreatic islets. Dysfunction of these cells is a key factor in the loss of glucose regulation that characterizes type 2 diabetes. The regulation of many of the functions of β-cells relies on their close interaction with the intra-islet microvasculature, comprised of endothelial cells and pericytes. In addition to providing islet blood supply, cells of the islet vasculature directly regulate β-cell activity through the secretion of growth factors and other molecules. These factors come from capillary mural pericytes and endothelial cells, and have been shown to promote insulin gene expression, insulin secretion, and β-cell proliferation. This review focuses on the intimate crosstalk of the vascular cells and β-cells and its role in glucose homeostasis and diabetes.
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Affiliation(s)
- Guzel Burganova
- Department of Cell and Development Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Claire Bridges
- Charles Perkins Centre, Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia
| | - Peter Thorn
- Charles Perkins Centre, Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia
| | - Limor Landsman
- Department of Cell and Development Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- *Correspondence: Limor Landsman,
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16
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Arous C, Mizgier ML, Rickenbach K, Pinget M, Bouzakri K, Wehrle-Haller B. Integrin and autocrine IGF2 pathways control fasting insulin secretion in β-cells. J Biol Chem 2020; 295:16510-16528. [PMID: 32934005 PMCID: PMC7864053 DOI: 10.1074/jbc.ra120.012957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 08/09/2020] [Indexed: 12/20/2022] Open
Abstract
Elevated levels of fasting insulin release and insufficient glucose-stimulated insulin secretion (GSIS) are hallmarks of diabetes. Studies have established cross-talk between integrin signaling and insulin activity, but more details of how integrin-dependent signaling impacts the pathophysiology of diabetes are needed. Here, we dissected integrin-dependent signaling pathways involved in the regulation of insulin secretion in β-cells and studied their link to the still debated autocrine regulation of insulin secretion by insulin/insulin-like growth factor (IGF) 2-AKT signaling. We observed for the first time a cooperation between different AKT isoforms and focal adhesion kinase (FAK)-dependent adhesion signaling, which either controlled GSIS or prevented insulin secretion under fasting conditions. Indeed, β-cells form integrin-containing adhesions, which provide anchorage to the pancreatic extracellular matrix and are the origin of intracellular signaling via FAK and paxillin. Under low-glucose conditions, β-cells adopt a starved adhesion phenotype consisting of actin stress fibers and large peripheral focal adhesion. In contrast, glucose stimulation induces cell spreading, actin remodeling, and point-like adhesions that contain phospho-FAK and phosphopaxillin, located in small protrusions. Rat primary β-cells and mouse insulinomas showed an adhesion remodeling during GSIS resulting from autocrine insulin/IGF2 and AKT1 signaling. However, under starving conditions, the maintenance of stress fibers and the large adhesion phenotype required autocrine IGF2-IGF1 receptor signaling mediated by AKT2 and elevated FAK-kinase activity and ROCK-RhoA levels but low levels of paxillin phosphorylation. This starved adhesion phenotype prevented excessive insulin granule release to maintain low insulin secretion during fasting. Thus, deregulation of the IGF2 and adhesion-mediated signaling may explain dysfunctions observed in diabetes.
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Affiliation(s)
- Caroline Arous
- Department of Cell Physiology and Metabolism, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland.
| | - Maria Luisa Mizgier
- UMR DIATHEC, Centre Européen d'Etude du Diabète, UMR DIATHEC, Strasbourg, France
| | - Katharina Rickenbach
- Department of Cell Physiology and Metabolism, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
| | - Michel Pinget
- UMR DIATHEC, Centre Européen d'Etude du Diabète, UMR DIATHEC, Strasbourg, France
| | - Karim Bouzakri
- UMR DIATHEC, Centre Européen d'Etude du Diabète, UMR DIATHEC, Strasbourg, France
| | - Bernhard Wehrle-Haller
- Department of Cell Physiology and Metabolism, Centre Médical Universitaire, University of Geneva, Geneva, Switzerland
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17
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Singh R, Cottle L, Loudovaris T, Xiao D, Yang P, Thomas HE, Kebede MA, Thorn P. Enhanced structure and function of human pluripotent stem cell-derived beta-cells cultured on extracellular matrix. Stem Cells Transl Med 2020; 10:492-505. [PMID: 33145960 PMCID: PMC7900592 DOI: 10.1002/sctm.20-0224] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 10/07/2020] [Accepted: 10/09/2020] [Indexed: 12/14/2022] Open
Abstract
The differentiation of human stem cells into insulin secreting beta‐like cells holds great promise to treat diabetes. Current protocols drive stem cells through stages of directed differentiation and maturation and produce cells that secrete insulin in response to glucose. Further refinements are now needed to faithfully phenocopy the responses of normal beta cells. A critical factor in normal beta cell behavior is the islet microenvironment which plays a central role in beta cell survival, proliferation, gene expression and secretion. One important influence on native cell responses is the capillary basement membrane. In adult islets, each beta cell makes a point of contact with basement membrane protein secreted by vascular endothelial cells resulting in structural and functional polarization. Interaction with basement membrane proteins triggers local activation of focal adhesions, cell orientation, and targeting of insulin secretion. This study aims to identifying the role of basement membrane proteins on the structure and function of human embryonic stem cell and induced pluripotent stem cell‐derived beta cells. Here, we show that differentiated human stem cells‐derived spheroids do contain basement membrane proteins as a diffuse web‐like structure. However, the beta‐like cells within the spheroid do not polarize in response to this basement membrane. We demonstrate that 2D culture of the differentiated beta cells on to basement membrane proteins enforces cell polarity and favorably alters glucose dependent insulin secretion.
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Affiliation(s)
- Reena Singh
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, New South Wales, Australia
| | - Louise Cottle
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, New South Wales, Australia
| | | | - Di Xiao
- Computational Systems Biology Group, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia
| | - Pengyi Yang
- Computational Systems Biology Group, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia.,Charles Perkins Centre, School of Mathematics and Statistics, University of Sydney, Sydney, New South Wales, Australia
| | - Helen E Thomas
- St Vincent's Institute, Fitzroy, Victoria, Australia.,Department of Medicine, St Vincent's Hospital, The University of Melbourne, Fitzroy, Victoria, Australia
| | - Melkam A Kebede
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, New South Wales, Australia
| | - Peter Thorn
- Charles Perkins Centre, Discipline of Physiology, School of Medical Sciences, University of Sydney, Camperdown, New South Wales, Australia
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18
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Gan WJ, Do OH, Cottle L, Ma W, Kosobrodova E, Cooper-White J, Bilek M, Thorn P. Local Integrin Activation in Pancreatic β Cells Targets Insulin Secretion to the Vasculature. Cell Rep 2019; 24:2819-2826.e3. [PMID: 30208309 DOI: 10.1016/j.celrep.2018.08.035] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 07/20/2018] [Accepted: 08/13/2018] [Indexed: 01/10/2023] Open
Abstract
The extracellular matrix (ECM) critically affects β cell functions via integrin activation. But whether these ECM actions drive the spatial organization of β cells, as they do in epithelial cells, is unknown. Here, we show that within islets of Langerhans, focal adhesion activation in β cells occurs exclusively where they contact the capillary ECM (vascular face). In cultured β cells, 3D mapping shows enriched insulin granule fusion where the cells contact ECM-coated coverslips, which depends on β1 integrin receptor activation. Culture on micro-contact printed stripes of E-cadherin and fibronectin shows that β cell contact at the fibronectin stripe selectively activates focal adhesions and enriches exocytic machinery and insulin granule fusion. Culture of cells in high glucose, as a model of glucotoxicity, abolishes granule targeting. We conclude that local integrin activation targets insulin secretion to the islet capillaries. This mechanism might be important for islet function and may change in disease.
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Affiliation(s)
- Wan Jun Gan
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Oanh Hoang Do
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Louise Cottle
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Wei Ma
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia
| | - Elena Kosobrodova
- School of Physics, University of Sydney, Camperdown, NSW 2006, Australia
| | - Justin Cooper-White
- Australian Institute for Bioengineering and Nanotechnology, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Marcela Bilek
- School of Physics, University of Sydney, Camperdown, NSW 2006, Australia; School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Camperdown, NSW 2006, Australia; Sydney Nanoscience Institute, University of Sydney, Camperdown, NSW 2006, Australia
| | - Peter Thorn
- Department of Physiology, Charles Perkins Centre, University of Sydney, Camperdown, NSW 2006, Australia.
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19
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Lammert E, Thorn P. The Role of the Islet Niche on Beta Cell Structure and Function. J Mol Biol 2019; 432:1407-1418. [PMID: 31711959 DOI: 10.1016/j.jmb.2019.10.032] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 01/15/2023]
Abstract
The islets of Langerhans or pancreatic islets are pivotal in the control of blood glucose and are complex microorgans embedded within the larger volume of the exocrine pancreas. Humans can have ~3.2 million islets [1] which, to our current knowledge, function in a similar manner to sense circulating blood glucose levels and respond with the secretion of a mix of different hormones that act to maintain glucose concentrations around a specific set point [2]. At a cellular level, the control of hormone secretion by glucose and other secretagogues is well-understood [3]. The key signal cascades have been identified and many details of the secretory process are known. However, if we shift focus from single cells and consider cells within intact islets, we do not have a comprehensive model as to how the islet environment influences cell function and how the islets work as a whole. This is important because there is overwhelming evidence that the structure and function of the individual endocrine cells are dramatically affected by the islet environment [4,5]. Uncovering the influence of this islet niche might drive future progress in treatments for Type 2 diabetes [6] and cell replacement therapies for Type 1 diabetes [7]. In this review, we focus on the insulin secreting beta cells and their interactions with the immediate environment that surrounds them including endocrine-endocrine interactions and contacts with capillaries.
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Affiliation(s)
- Eckhard Lammert
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany; Institute for Vascular and Islet Cell Biology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University, Düsseldorf, Germany; German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
| | - Peter Thorn
- Charles Perkins Centre, School of Medical Sciences, University of Sydney, Camperdown, NSW 2006, Australia.
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20
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Yang J, Lv Y, Zhao Z, Li W, Xiang S, Zhou L, Gao A, Yan B, Ou L, Ling H, Xiao X, Liu J. A microRNA‑24‑to‑secretagogin regulatory pathway mediates cholesterol‑induced inhibition of insulin secretion. Int J Mol Med 2019; 44:608-616. [PMID: 31173188 PMCID: PMC6605698 DOI: 10.3892/ijmm.2019.4224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 05/20/2019] [Indexed: 12/16/2022] Open
Abstract
Hypercholesterolemia is a key factor leading to β‑cell dysfunction, but its underlying mechanisms remain unclear. Secretagogin (Scgn), a Ca2+ sensor protein that is expressed at high levels in the islets, has been shown to play a key role in regulating insulin secretion through effects on the soluble N‑ethylmaleimide‑sensitive factor attachment receptor protein complexes. However, further studies are required to determine whether Scgn plays a role in hypercholesterolemia‑associated β‑cell dysfunction. The present study investigated the involvement of a microRNA‑24 (miR‑24)‑to‑Scgn regulatory pathway in cholesterol‑induced β‑cell dysfunction. In the present study, MIN6 cells were treated with increasing concentrations of cholesterol and then, the cellular functions and changes in the miR‑24‑to‑Scgn signal pathway were observed. Excessive uptake of cholesterol in MIN6 cells increased the expression of miR‑24, resulting in a reduction in Sp1 expression by directly targeting its 3' untranslated region. As a transcriptional activator of Scgn, downregulation of Sp1 decreased Scgn levels and subsequently decreased the phosphorylation of focal adhesion kinase and paxillin, which is regulated by Scgn. Therefore, the focal adhesions in insulin granules were impaired and insulin exocytosis was reduced. The present study concluded that a miR‑24‑to‑Scgn pathway participates in the mechanism regulating cholesterol accumulation‑induced β‑cell dysfunction.
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Affiliation(s)
- Jing Yang
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Yuncheng Lv
- Laboratory of Clinical Anatomy and Reproductive Medicine, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Zhibo Zhao
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Wu Li
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Sunmin Xiang
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Lingzhi Zhou
- Department of Paediatrics, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Anbo Gao
- Laboratory of Clinical Anatomy and Reproductive Medicine, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Bin Yan
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Lingling Ou
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Hong Ling
- Emergency Surgery, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Xinhua Xiao
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
| | - Jianghua Liu
- Department of Endocrinology, The First Affiliated Hospital of The University of South China, Hengyang, Hunan 421001, P.R. China
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21
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Xu Z, Isaji T, Fukuda T, Wang Y, Gu J. O-GlcNAcylation regulates integrin-mediated cell adhesion and migration via formation of focal adhesion complexes. J Biol Chem 2018; 294:3117-3124. [PMID: 30587575 DOI: 10.1074/jbc.ra118.005923] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/02/2018] [Indexed: 01/08/2023] Open
Abstract
O-GlcNAcylation is a post-translational modification of a protein serine or threonine residue catalyzed by O-GlcNAc transferase (OGT) in the nucleus and cytoplasm. O-GlcNAcylation plays important roles in the cellular signaling that affect the different biological functions of cells, depending upon cell type. However, whether or not O-GlcNAcylation regulates cell adhesion and migration remains unclear. Here, we used the doxycycline-inducible short hairpin RNA (shRNA) system to establish an OGT knockdown (KD) HeLa cell line and found that O-GlcNAcylation is a key regulator for cell adhesion, migration, and focal adhesion (FA) complex formation. The expression levels of OGT and O-GlcNAcylation were remarkably suppressed 24 h after induction of doxycycline. Knockdown of OGT significantly promoted cell adhesion, but it suppressed the cell migration on fibronectin. The immunostaining with paxillin, a marker for FA plaque, clearly showed that the number of FAs was increased in the KD cells compared with that in the control cells. The O-GlcNAcylation levels of paxillin, talin, and focal adhesion kinase were down-regulated in KD cells. Interestingly, the complex formation between integrin β1, focal adhesion kinase, paxillin, and talin was greatly increased in KD cells. Consistently, levels of active integrin β1 were significantly enhanced in KD cells, whereas they were decreased in cells overexpressing OGT. The data suggest a novel regulatory mechanism for O-GlcNAcylation during FA complex formation, which thereby affects integrin activation and integrin-mediated functions such as cell adhesion and migration.
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Affiliation(s)
- Zhiwei Xu
- From the Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai Miyagi 981-8558, Japan and
| | - Tomoya Isaji
- From the Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai Miyagi 981-8558, Japan and
| | - Tomohiko Fukuda
- From the Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai Miyagi 981-8558, Japan and
| | - Yuqin Wang
- the Department of Pharmacology, Pharmacy College, Nantong University, Nantong, Jiangsu Province 226001, China
| | - Jianguo Gu
- From the Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai Miyagi 981-8558, Japan and
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22
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Kang T, Jensen P, Solovyeva V, Brewer JR, Larsen MR. Dynamic Changes in the Protein Localization in the Nuclear Environment in Pancreatic β-Cell after Brief Glucose Stimulation. J Proteome Res 2018. [PMID: 29518335 DOI: 10.1021/acs.jproteome.7b00930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Characterization of molecular mechanisms underlying pancreatic β-cell function in relation to glucose-stimulated insulin secretion is incomplete, especially with respect to global response in the nuclear environment. We focus on the characterization of proteins in the nuclear environment of β-cells after brief, high glucose stimulation. We compared purified nuclei derived from β-cells stimulated with 17 mM glucose for 0, 2, and 5 min using quantitative proteomics, a time frame that most likely does not result in translation of new protein in the cell. Among the differentially regulated proteins, we identified 20 components of the nuclear organization processes, including nuclear pore organization, ribonucleoprotein complex, and pre-mRNA transcription. We found alteration of the nuclear pore complex, together with calcium/calmodulin-binding chaperones that facilitate protein and RNA import or export to/from the nucleus to the cytoplasm. Putative insulin mRNA transcription-associated factors were identified among the regulated proteins, and they were cross-validated by Western blotting and confocal immunofluorescence imaging. Collectively, our data suggest that protein translocation between the nucleus and the cytoplasm is an important process, highly involved in the initial molecular mechanism underlying glucose-stimulated insulin secretion in pancreatic β-cells.
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Affiliation(s)
- Taewook Kang
- Protein Research Group, Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - Pia Jensen
- Protein Research Group, Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - Vita Solovyeva
- MEMPHYS-Centre for Biomembrane Physics, Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - Jonathan R Brewer
- MEMPHYS-Centre for Biomembrane Physics, Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense M , Denmark
| | - Martin R Larsen
- Protein Research Group, Department of Biochemistry and Molecular Biology , University of Southern Denmark , DK-5230 Odense M , Denmark
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23
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Kosobrodova E, Gan WJ, Kondyurin A, Thorn P, Bilek MMM. Improved Multiprotein Microcontact Printing on Plasma Immersion Ion Implanted Polystyrene. ACS APPLIED MATERIALS & INTERFACES 2018; 10:227-237. [PMID: 29211435 DOI: 10.1021/acsami.7b15545] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Multiprotein micropatterning allows the creation of complex, controlled microenvironments for single cells that can be used for the study of the localized effects of various proteins and signals on cell survival, development, and functions. To enable analysis of cell interactions with microprinted proteins, the multiprotein micropattern must have low cross-contamination and high long-term stability in a cell culture medium. To achieve this, we employed an optimized plasma ion immersion implantation (PIII) treatment to provide polystyrene (PS) with the ability to covalently immobilize proteins on contact while retaining sufficient transparency and suitable surface properties for contact printing and retention of protein activity. The quality and long-term stability of the micropatterns on untreated and PIII treated PS were compared with those on glass using confocal microscopy. The protein micropattern on the PIII treated PS was more uniform and had a significantly higher contrast that was not affected by long-term incubation in cell culture media because the proteins were covalently bonded to PIII treated PS. The immunostaining of mouse pancreatic β cells interacting with E-cadherin and fibronectin striped surfaces showed phosphorylated paxillin concentrated on cell edges over the fibronectin stripes. This indicates that multiprotein micropatterns printed on PIII treated PS can be used for high-resolution studies of local influence on cell morphology and protein production.
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Affiliation(s)
- E Kosobrodova
- The School of Physics, University of Sydney , Sydney, New South Wales 2006, Australia
| | - W J Gan
- Department of Physiology, Sydney Medical School, Charles Perkins Centre, University of Sydney , Sydney, New South Wales 2006, Australia
| | - A Kondyurin
- The School of Physics, University of Sydney , Sydney, New South Wales 2006, Australia
| | - P Thorn
- Department of Physiology, Sydney Medical School, Charles Perkins Centre, University of Sydney , Sydney, New South Wales 2006, Australia
| | - M M M Bilek
- The School of Physics, University of Sydney , Sydney, New South Wales 2006, Australia
- Department of Physiology, Sydney Medical School, Charles Perkins Centre, University of Sydney , Sydney, New South Wales 2006, Australia
- The School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney , Sydney, New South Wales 2006, Australia
- The Australian Institute of Nanoscale Science and Technology, University of Sydney , Sydney, New South Wales 2006, Australia
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24
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Gudmundsdottir V, Pedersen HK, Allebrandt KV, Brorsson C, van Leeuwen N, Banasik K, Mahajan A, Groves CJ, van de Bunt M, Dawed AY, Fritsche A, Staiger H, Simonis-Bik AMC, Deelen J, Kramer MHH, Dietrich A, Hübschle T, Willemsen G, Häring HU, de Geus EJC, Boomsma DI, Eekhoff EMW, Ferrer J, McCarthy MI, Pearson ER, Gupta R, Brunak S, 't Hart LM. Integrative network analysis highlights biological processes underlying GLP-1 stimulated insulin secretion: A DIRECT study. PLoS One 2018; 13:e0189886. [PMID: 29293525 PMCID: PMC5749727 DOI: 10.1371/journal.pone.0189886] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 12/04/2017] [Indexed: 11/18/2022] Open
Abstract
Glucagon-like peptide 1 (GLP-1) stimulated insulin secretion has a considerable heritable component as estimated from twin studies, yet few genetic variants influencing this phenotype have been identified. We performed the first genome-wide association study (GWAS) of GLP-1 stimulated insulin secretion in non-diabetic individuals from the Netherlands Twin register (n = 126). This GWAS was enhanced using a tissue-specific protein-protein interaction network approach. We identified a beta-cell protein-protein interaction module that was significantly enriched for low gene scores based on the GWAS P-values and found support at the network level in an independent cohort from Tübingen, Germany (n = 100). Additionally, a polygenic risk score based on SNPs prioritized from the network was associated (P < 0.05) with glucose-stimulated insulin secretion phenotypes in up to 5,318 individuals in MAGIC cohorts. The network contains both known and novel genes in the context of insulin secretion and is enriched for members of the focal adhesion, extracellular-matrix receptor interaction, actin cytoskeleton regulation, Rap1 and PI3K-Akt signaling pathways. Adipose tissue is, like the beta-cell, one of the target tissues of GLP-1 and we thus hypothesized that similar networks might be functional in both tissues. In order to verify peripheral effects of GLP-1 stimulation, we compared the transcriptome profiling of ob/ob mice treated with liraglutide, a clinically used GLP-1 receptor agonist, versus baseline controls. Some of the upstream regulators of differentially expressed genes in the white adipose tissue of ob/ob mice were also detected in the human beta-cell network of genes associated with GLP-1 stimulated insulin secretion. The findings provide biological insight into the mechanisms through which the effects of GLP-1 may be modulated and highlight a potential role of the beta-cell expressed genes RYR2, GDI2, KIAA0232, COL4A1 and COL4A2 in GLP-1 stimulated insulin secretion.
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Affiliation(s)
- Valborg Gudmundsdottir
- Department of Bio and Health Informatics, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Helle Krogh Pedersen
- Department of Bio and Health Informatics, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Karla Viviani Allebrandt
- Department of Translational Bioinformatics, R&D Operations, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, Frankfurt, Germany
| | - Caroline Brorsson
- Department of Bio and Health Informatics, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Nienke van Leeuwen
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Karina Banasik
- Novo Nordisk Foundation Center for Protein Research, Disease Systems Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Wellcome Trust Center for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Anubha Mahajan
- Oxford NIHR Biomedical Research Center, Oxford, United Kingdom
| | - Christopher J Groves
- Oxford Center for Diabetes Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Martijn van de Bunt
- Oxford NIHR Biomedical Research Center, Oxford, United Kingdom.,Oxford Center for Diabetes Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Adem Y Dawed
- Division of Molecular & Clinical Medicine, School of Medicine, University of Dundee, Dundee, United Kingdom
| | - Andreas Fritsche
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University Tübingen, Member of the German Centre for Diabetes Research (DZD), Tübingen, Germany
| | - Harald Staiger
- Institute of Pharmaceutical Sciences, Department of Pharmacy and Biochemistry, Eberhard Karls University, Tübingen, Germany
| | - Annemarie M C Simonis-Bik
- Department of Internal Medicine, Diabetes Center and Endocrinology, VU University Medical Center, Amsterdam, The Netherlands
| | - Joris Deelen
- Section Molecular Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.,Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Mark H H Kramer
- Department of Internal Medicine, Diabetes Center and Endocrinology, VU University Medical Center, Amsterdam, The Netherlands
| | - Axel Dietrich
- Department of Translational Bioinformatics, R&D Operations, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, Frankfurt, Germany
| | - Thomas Hübschle
- Department GI Endocrinology, R&D Diabetes Division, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, Frankfurt, Germany
| | - Gonneke Willemsen
- Department of Biological Psychology, Vrije Universiteit and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Hans-Ulrich Häring
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, Eberhard Karls University Tübingen, Member of the German Centre for Diabetes Research (DZD), Tübingen, Germany
| | - Eco J C de Geus
- Department of Biological Psychology, Vrije Universiteit and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.,Netherlands Consortium for Healthy Aging, Leiden, The Netherlands
| | - Dorret I Boomsma
- Department of Biological Psychology, Vrije Universiteit and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Elisabeth M W Eekhoff
- Department of Internal Medicine, Diabetes Center and Endocrinology, VU University Medical Center, Amsterdam, The Netherlands
| | - Jorge Ferrer
- Section of Epigenomics and Disease, Department of Medicine, Imperial College London, London, United Kingdom.,Genomic Programming of Beta Cells Laboratory, Institut d'Investigacions Biomediques August Pi I Sunyer (IDIBAPS), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
| | - Mark I McCarthy
- Wellcome Trust Center for Human Genetics, University of Oxford, Oxford, United Kingdom.,Oxford NIHR Biomedical Research Center, Oxford, United Kingdom.,Oxford Center for Diabetes Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom
| | - Ewan R Pearson
- Division of Molecular & Clinical Medicine, School of Medicine, University of Dundee, Dundee, United Kingdom
| | - Ramneek Gupta
- Department of Bio and Health Informatics, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Søren Brunak
- Department of Bio and Health Informatics, Technical University of Denmark, Kongens Lyngby, Denmark.,Novo Nordisk Foundation Center for Protein Research, Disease Systems Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Leen M 't Hart
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.,Section Molecular Epidemiology, Leiden University Medical Center, Leiden, The Netherlands
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25
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Kang T, Jensen P, Huang H, Lund Christensen G, Billestrup N, Larsen MR. Characterization of the Molecular Mechanisms Underlying Glucose Stimulated Insulin Secretion from Isolated Pancreatic β-cells Using Post-translational Modification Specific Proteomics (PTMomics). Mol Cell Proteomics 2017; 17:95-110. [PMID: 29113996 DOI: 10.1074/mcp.ra117.000217] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/20/2017] [Indexed: 01/01/2023] Open
Abstract
Normal pancreatic islet β-cells (PBCs) abundantly secrete insulin in response to elevated blood glucose levels, in order to maintain an adequate control of energy balance and glucose homeostasis. However, the molecular mechanisms underlying the insulin secretion are unclear. Improving our understanding of glucose-stimulated insulin secretion (GSIS) mechanisms under normal conditions is a prerequisite for developing better interventions against diabetes. Here, we aimed at identifying novel signaling pathways involved in the initial release of insulin from PBCs after glucose stimulation using quantitative strategies for the assessment of phosphorylated proteins and sialylated N-linked (SA) glycoproteins.Islets of Langerhans derived from newborn rats with a subsequent 9-10 days of maturation in vitro were stimulated with 20 mm glucose for 0 min (control), 5 min, 10 min, and 15 min. The isolated islets were subjected to time-resolved quantitative phosphoproteomics and sialiomics using iTRAQ-labeling combined with enrichment of phosphorylated peptides and formerly SA glycopeptides and high-accuracy LC-MS/MS. Using bioinformatics we analyzed the functional signaling pathways during GSIS, including well-known insulin secretion pathways. Furthermore, we identified six novel activated signaling pathways (e.g. agrin interactions and prolactin signaling) at 15 min GSIS, which may increase our understanding of the molecular mechanism underlying GSIS. Moreover, we validated some of the regulated phosphosites by parallel reaction monitoring, which resulted in the validation of eleven new phosphosites significantly regulated on GSIS. Besides protein phosphorylation, alteration in SA glycosylation was observed on several surface proteins on brief GSIS. Interestingly, proteins important for cell-cell interaction, cell movement, cell-ECM interaction and Focal Adhesion (e.g. integrins, semaphorins, and plexins) were found regulated at the level of sialylation, but not in protein expression. Collectively, we believe that this comprehensive Proteomics and PTMomics survey of signaling pathways taking place during brief GSIS of primary PBCs is contributing to understanding the complex signaling underlying GSIS.
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Affiliation(s)
- Taewook Kang
- From the ‡Department of Biochemistry and Molecular Biology, PR group, University of Southern Denmark, Odense, Denmark
| | - Pia Jensen
- From the ‡Department of Biochemistry and Molecular Biology, PR group, University of Southern Denmark, Odense, Denmark
| | - Honggang Huang
- From the ‡Department of Biochemistry and Molecular Biology, PR group, University of Southern Denmark, Odense, Denmark
| | - Gitte Lund Christensen
- §Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Nils Billestrup
- §Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Martin R Larsen
- From the ‡Department of Biochemistry and Molecular Biology, PR group, University of Southern Denmark, Odense, Denmark;
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26
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Leduc M, Richard J, Costes S, Muller D, Varrault A, Compan V, Mathieu J, Tanti JF, Pagès G, Pouyssegur J, Bertrand G, Dalle S, Ravier MA. ERK1 is dispensable for mouse pancreatic beta cell function but is necessary for glucose-induced full activation of MSK1 and CREB. Diabetologia 2017; 60:1999-2010. [PMID: 28721437 DOI: 10.1007/s00125-017-4356-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 06/02/2017] [Indexed: 11/24/2022]
Abstract
AIMS/HYPOTHESIS Insufficient insulin secretion from pancreatic beta cells, which is associated with a decrease in beta cell mass, is a characteristic of type 2 diabetes. Extracellular signal-related kinase 1 and 2 (ERK1/2) inhibition in beta cells has been reported to affect insulin secretion, gene transcription and survival, although whether ERK1 and ERK2 play distinct roles is unknown. The aim of this study was to assess the individual roles of ERK1 and ERK2 in beta cells using ERK1 (also known as Mapk3)-knockout mice (Erk1 -/- mice) and pharmacological approaches. METHODS NAD(P)H, free cytosolic Ca2+ concentration and insulin secretion were determined in islets. ERK1 and ERK2 subplasmalemmal translocation and activity was monitored using total internal reflection fluorescence microscopy. ERK1/2, mitogen and stress-activated kinase1 (MSK1) and cAMP-responsive element-binding protein (CREB) activation were evaluated by western blot and/or immunocytochemistry. The islet mass was determined from pancreatic sections. RESULTS Glucose induced rapid subplasmalemmal recruitment of ERK1 and ERK2. When both ERK1 and ERK2 were inhibited simultaneously, the rapid transient peak of the first phase of glucose-induced insulin secretion was reduced by 40% (p < 0.01), although ERK1 did not appear to be involved in this process. By contrast, ERK1 was required for glucose-induced full activation of several targets involved in beta cell survival; MSK1 and CREB were less active in Erk1 -/- mouse beta cells (p < 0.01) compared with Erk1 +/+ mouse beta cells, and their phosphorylation could only be restored when ERK1 was re-expressed and not when ERK2 was overexpressed. Finally, the islet mass of Erk1 -/- mice was slightly increased in young animals (4-month-old mice) vs Erk1 +/+ mice (section occupied by islets [mean ± SEM]: 0.74% ± 0.03% vs 0.62% ± 0.04%; p < 0.05), while older mice (10 months old) were less prone to age-associated pancreatic peri-insulitis (infiltrated islets [mean ± SEM]: 7.51% ± 1.34% vs 2.03% ± 0.51%; p < 0.001). CONCLUSIONS/INTERPRETATION ERK1 and ERK2 play specific roles in beta cells. ERK2 cannot always compensate for the lack of ERK1 but the absence of a clear-cut phenotype in Erk1 -/- mice shows that ERK1 is dispensable in normal conditions.
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Affiliation(s)
- Michele Leduc
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Joy Richard
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Safia Costes
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Dany Muller
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Annie Varrault
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Vincent Compan
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Julia Mathieu
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Jean-François Tanti
- Faculté de Médecine, Centre Méditerranéen de Médecine Moléculaire, Inserm U1065, Université de Nice Sophia Antipolis, Nice, France
| | - Gilles Pagès
- Institute for Research on Cancer and Aging, Nice (IRCAN), Centre Antoine Lacassagne, Université de Nice Sophia Antipolis, Nice, France
| | - Jacques Pouyssegur
- Institute for Research on Cancer and Aging, Nice (IRCAN), Centre Antoine Lacassagne, Université de Nice Sophia Antipolis, Nice, France
- Medical Biology Department, Centre Scientifique de Monaco (CSM), Monaco, Principality of Monaco
| | - Gyslaine Bertrand
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Stéphane Dalle
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France
| | - Magalie A Ravier
- Institut de Génomique Fonctionnelle, Centre National de la Recherche Scientifique (CNRS), Inserm, Université de Montpellier, 141 Rue de la Cardonille, 34094, Montpellier CEDEX 5, France.
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27
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Critical role of β1 integrin in postnatal beta-cell function and expansion. Oncotarget 2017; 8:62939-62952. [PMID: 28968961 PMCID: PMC5609893 DOI: 10.18632/oncotarget.17969] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 04/21/2017] [Indexed: 12/29/2022] Open
Abstract
β1 integrin is essential for pancreatic beta-cell development and maintenance in rodents and humans. However, the effects of a temporal beta-cell specific β1 integrin knockout on adult islet function are unknown. We utilized a mouse insulin 1 promoter driven tamoxifen-inducible Cre-recombinase β1 integrin knockout mouse model (MIPβ1KO) to investigate β1 integrin function in adult pancreatic beta-cells. Adult male MIPβ1KO mice were significantly glucose intolerant due to impaired glucose-stimulated insulin secretion in vivo and ex vivo at 8 weeks post-tamoxifen. The expression of Insulin and Pancreatic and duodenal homeobox-1 mRNA was significantly reduced in MIPβ1KO islets, along with reductions in insulin exocytotic proteins. Morphological analyses demonstrated that beta-cell mass, islet density, and the number of large-sized islets was significantly reduced in male MIPβ1KO mice. Significant reductions in the phosphorylation of signaling molecules focal adhesion kinase, extracellular signal-regulated kinases 1 and 2, and v-Akt murine thymoma viral oncogene were observed in male MIPβ1KO islets when compared to controls. MIPβ1KO islets displayed a significant increase in protein levels of the apoptotic marker cleaved-Poly (ADP-ribose) polymerase and a reduction of the cell cycle marker cyclin D1. Female MIPβ1KO mice did not develop glucose intolerance or reduced beta-cell mass until 16 weeks post-tamoxifen. Glucose intolerance remained in both genders of aged MIPβ1KO mice. This data demonstrates that β1 integrin is required for the maintenance of glucose homeostasis through postnatal beta-cell function and expansion.
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28
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Arous C, Wehrle-Haller B. Role and impact of the extracellular matrix on integrin-mediated pancreatic β-cell functions. Biol Cell 2017; 109:223-237. [PMID: 28266044 DOI: 10.1111/boc.201600076] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 03/01/2017] [Accepted: 03/02/2017] [Indexed: 12/17/2022]
Abstract
Understanding the organisation and role of the extracellular matrix (ECM) in islets of Langerhans is critical for maintaining pancreatic β-cells, and to recognise and revert the physiopathology of diabetes. Indeed, integrin-mediated adhesion signalling in response to the pancreatic ECM plays crucial roles in β-cell survival and insulin secretion, two major functions, which are affected in diabetes. Here, we would like to present an update on the major components of the pancreatic ECM, their role during integrin-mediated cell-matrix adhesions and how they are affected during diabetes. To treat diabetes, a promising approach consists in replacing β-cells by transplantation. However, efficiency is low, because β-cells suffer of anoikis, due to enzymatic digestion of the pancreatic ECM, which affects the survival of insulin-secreting β-cells. The strategy of adding ECM components during transplantation, to reproduce the pancreatic microenvironment, is a challenging task, as many of the regulatory mechanisms that control ECM deposition and turnover are not sufficiently understood. A better comprehension of the impact of the ECM on the adhesion and integrin-dependent signalling in β-cells is primordial to improve the healthy state of islets to prevent the onset of diabetes as well as for enhancing the efficiency of the islet transplantation therapy.
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Affiliation(s)
- Caroline Arous
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, Geneva, Switzerland
| | - Bernhard Wehrle-Haller
- Department of Cell Physiology and Metabolism, University of Geneva Medical Center, Geneva, Switzerland
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29
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Haywood NJ, Cordell PA, Tang KY, Makova N, Yuldasheva NY, Imrie H, Viswambharan H, Bruns AF, Cubbon RM, Kearney MT, Wheatcroft SB. Insulin-Like Growth Factor Binding Protein 1 Could Improve Glucose Regulation and Insulin Sensitivity Through Its RGD Domain. Diabetes 2017; 66:287-299. [PMID: 28108607 DOI: 10.2337/db16-0997] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 10/26/2016] [Indexed: 11/13/2022]
Abstract
Low circulating levels of insulin-like growth factor binding protein 1 (IGFBP-1) are associated with insulin resistance and predict the development of type 2 diabetes. IGFBP-1 can affect cellular functions independently of IGF binding through an Arg-Gly-Asp (RGD) integrin-binding motif. Whether causal mechanisms underlie the favorable association of high IGFBP-1 levels with insulin sensitivity and whether these could be exploited therapeutically remain unexplored. We used recombinant IGFBP-1 and a synthetic RGD-containing hexapeptide in complementary in vitro signaling assays and in vivo metabolic profiling in obese mice to investigate the effects of IGFBP-1 and its RGD domain on insulin sensitivity, insulin secretion, and whole-body glucose regulation. The RGD integrin-binding domain of IGFBP-1, through integrin engagement, focal adhesion kinase, and integrin-linked kinase, enhanced insulin sensitivity and insulin secretion in C2C12 myotubes and INS-1 832/13 pancreatic β-cells. Both acute administration and chronic infusion of an RGD synthetic peptide to obese C57BL/6 mice improved glucose clearance and insulin sensitivity. These favorable effects on metabolic homeostasis suggest that the RGD integrin-binding domain of IGFBP-1 may be a promising candidate for therapeutic development in the field of insulin resistance.
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Affiliation(s)
- Natalie J Haywood
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Paul A Cordell
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Kar Yeun Tang
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Natallia Makova
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Nadira Y Yuldasheva
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Helen Imrie
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Hema Viswambharan
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Alexander F Bruns
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Richard M Cubbon
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Mark T Kearney
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K
| | - Stephen B Wheatcroft
- Division of Cardiovascular and Diabetes Research, Leeds Multidisciplinary Cardiovascular Research Centre, Faculty of Medicine and Health, University of Leeds, Leeds, West Yorkshire, U.K.
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Zeng FM, Xie YM, Liao LD, Li LY, Chen B, Xie JJ, Xu LY, Li EM. Biological characterization of three immortalized esophageal epithelial cell lines. Mol Med Rep 2016; 14:4802-4810. [PMID: 27748861 DOI: 10.3892/mmr.2016.5813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 09/02/2016] [Indexed: 11/06/2022] Open
Abstract
The key molecular events that contribute to tumorigenesis are incompletely understood. The aim of the present study was to characterize and compare the biological phenotypes of three human telomerase reverse transcriptase (hTERT) and/or human papillomavirus 16 E6 and E7‑immortalized esophageal epithelial cell lines, NE2‑hTERT (NE2), NE3‑E6E7‑hTERT (NE3) and NEcA6‑E6E7‑hTERT (NEcA6). The present study used soft‑agar colony formation assays, tumorigenicity assays in nude mice, and cell proliferation, adhesion and migration assays to identify the biological characteristics of NE2, NE3 and NEcA6 cells. NE2 and NE3 cells exhibited characteristics of benign cells, such as the inability to grow in soft agar or form tumors in nude mice. By contrast, NEcA6 cells had undergone transformation, as demonstrated by the ability to grow in soft agar and form tumors in nude mice. In addition, NEcA6 cells exhibited increased migration and adhesion capabilities when compared with NE2 and NE3 cells. In order to identify mechanism(s) that may contribute to the altered biological phenotypes exhibited by these cells, the expression of three proteins involved in modulating cell migration [fascin, ezrin/radixin/moesin family proteins and phosphorylated‑focal adhesion kinase (Tyr 397)], as well as the expression status and subcellular localization of three key focal adhesions components (paxillin, talin and kindlin‑2) were examined. Paxillin, talin and kindlin‑2 were localized to adhesive sites that connect F‑actin with the extracellular matrix in transformed NEcA6 cells, but were distributed in a diffuse manner in NE2 and NE3 cells. Knockdown of kindlin‑2 in NE3 and NEcA6 cells decreased cell adhesion, however, NEcA6 cells demonstrated a greater sensitivity to knockdown of kindlin‑2. No significant differences were observed in the protein expression levels of fascin, exrin/radixin/moesin and p‑FAK in the three cell lines. In conclusion, these results demonstrate that these three focal adhesion components, particularly kindlin‑2, may contribute to the carcinogenesis of esophageal squamous cells.
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Affiliation(s)
- Fa-Min Zeng
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
| | - Yang-Min Xie
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
| | - Lian-Di Liao
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
| | - Li-Yan Li
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
| | - Bo Chen
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
| | - Jian-Jun Xie
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
| | - Li-Yan Xu
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
| | - En-Min Li
- Key Laboratory of Molecular Biology for High Cancer Incidence in The Coastal Chaoshan Area, Medical College of Shantou University, Shantou, Guangdong 515041, P.R. China
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Quinault A, Gausseres B, Bailbe D, Chebbah N, Portha B, Movassat J, Tourrel-Cuzin C. Disrupted dynamics of F-actin and insulin granule fusion in INS-1 832/13 beta-cells exposed to glucotoxicity: partial restoration by glucagon-like peptide 1. Biochim Biophys Acta Mol Basis Dis 2016; 1862:1401-11. [DOI: 10.1016/j.bbadis.2016.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/22/2016] [Accepted: 04/11/2016] [Indexed: 01/11/2023]
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32
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Secretagogin affects insulin secretion in pancreatic β-cells by regulating actin dynamics and focal adhesion. Biochem J 2016; 473:1791-803. [PMID: 27095850 PMCID: PMC4901359 DOI: 10.1042/bcj20160137] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/18/2016] [Indexed: 01/03/2023]
Abstract
Secretagogin (SCGN), a Ca2+-binding protein having six EF-hands, is selectively expressed in pancreatic β-cells and neuroendocrine cells. Previous studies suggested that SCGN enhances insulin secretion by functioning as a Ca2+-sensor protein, but the underlying mechanism has not been elucidated. The present study explored the mechanism by which SCGN enhances glucose-induced insulin secretion in NIT-1 insulinoma cells. To determine whether SCGN influences the first or second phase of insulin secretion, we examined how SCGN affects the kinetics of insulin secretion in NIT-1 cells. We found that silencing SCGN suppressed the second phase of insulin secretion induced by glucose and H2O2, but not the first phase induced by KCl stimulation. Recruitment of insulin granules in the second phase of insulin secretion was significantly impaired by knocking down SCGN in NIT-1 cells. In addition, we found that SCGN interacts with the actin cytoskeleton in the plasma membrane and regulates actin remodelling in a glucose-dependent manner. Since actin dynamics are known to regulate focal adhesion, a critical step in the second phase of insulin secretion, we examined the effect of silencing SCGN on focal adhesion molecules, including FAK (focal adhesion kinase) and paxillin, and the cell survival molecules ERK1/2 (extracellular-signal-regulated kinase 1/2) and Akt. We found that glucose- and H2O2-induced activation of FAK, paxillin, ERK1/2 and Akt was significantly blocked by silencing SCGN. We conclude that SCGN controls glucose-stimulated insulin secretion and thus may be useful in the therapy of Type 2 diabetes.
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Welsh M, Jamalpour M, Zang G, Åkerblom B. The role of the Src Homology-2 domain containing protein B (SHB) in β cells. J Mol Endocrinol 2016; 56:R21-31. [PMID: 26489764 DOI: 10.1530/jme-15-0228] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/20/2015] [Indexed: 12/17/2022]
Abstract
This review will describe the SH2-domain signaling protein Src Homology-2 domain containing protein B (SHB) and its role in various physiological processes relating in particular to glucose homeostasis and β cell function. SHB operates downstream of several tyrosine kinase receptors and assembles signaling complexes in response to receptor activation by interacting with other signaling proteins via its other domains (proline-rich, phosphotyrosine-binding and tyrosine-phosphorylation sites). The subsequent responses are context-dependent. Absence of Shb in mice has been found to exert effects on hematopoiesis, angiogenesis and glucose metabolism. Specifically, first-phase insulin secretion in response to glucose was impaired and this effect was related to altered characteristics of focal adhesion kinase activation modulating signaling through Akt, ERK, β catenin and cAMP. It is believed that SHB plays a role in integrating adaptive responses to various stimuli by simultaneously modulating cellular responses in different cell-types, thus playing a role in maintaining physiological homeostasis.
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Affiliation(s)
- Michael Welsh
- Department of Medical Cell BiologyUppsala University, PO Box 571, Husargatan 3, SE-75123 Uppsala, Sweden
| | - Maria Jamalpour
- Department of Medical Cell BiologyUppsala University, PO Box 571, Husargatan 3, SE-75123 Uppsala, Sweden
| | - Guangxiang Zang
- Department of Medical Cell BiologyUppsala University, PO Box 571, Husargatan 3, SE-75123 Uppsala, Sweden
| | - Björn Åkerblom
- Department of Medical Cell BiologyUppsala University, PO Box 571, Husargatan 3, SE-75123 Uppsala, Sweden
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Lin Y, Sun Z. Antiaging Gene Klotho Attenuates Pancreatic β-Cell Apoptosis in Type 1 Diabetes. Diabetes 2015; 64:4298-311. [PMID: 26340932 PMCID: PMC4657580 DOI: 10.2337/db15-0066] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 08/25/2015] [Indexed: 12/20/2022]
Abstract
Apoptosis is the major cause of death of insulin-producing β-cells in type 1 diabetes mellitus (T1DM). Klotho is a recently discovered antiaging gene. We found that the Klotho gene is expressed in pancreatic β-cells. Interestingly, halplodeficiency of Klotho (KL(+/-)) exacerbated streptozotocin (STZ)-induced diabetes (a model of T1DM), including hyperglycemia, glucose intolerance, diminished islet insulin storage, and increased apoptotic β-cells. Conversely, in vivo β-cell-specific expression of mouse Klotho gene (mKL) attenuated β-cell apoptosis and prevented STZ-induced diabetes. mKL promoted cell adhesion to collagen IV, increased FAK and Akt phosphorylation, and inhibited caspase 3 cleavage in cultured MIN6 β-cells. mKL abolished STZ- and TNFα-induced inhibition of FAK and Akt phosphorylation, caspase 3 cleavage, and β-cell apoptosis. These promoting effects of Klotho can be abolished by blocking integrin β1. Therefore, these cell-based studies indicated that Klotho protected β-cells by inhibiting β-cell apoptosis through activation of the integrin β1-FAK/Akt pathway, leading to inhibition of caspase 3 cleavage. In an autoimmune T1DM model (NOD), we showed that in vivo β-cell-specific expression of mKL improved glucose tolerance, attenuated β-cell apoptosis, enhanced insulin storage in β-cells, and increased plasma insulin levels. The beneficial effect of Klotho gene delivery is likely due to attenuation of T-cell infiltration in pancreatic islets in NOD mice. Overall, our results demonstrate for the first time that Klotho protected β-cells in T1DM via attenuating apoptosis.
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MESH Headings
- Animals
- Apoptosis
- Autoimmunity
- Cell Adhesion
- Cell Line, Tumor
- Crosses, Genetic
- Diabetes Mellitus, Type 1/immunology
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/pathology
- Diabetes Mellitus, Type 1/prevention & control
- Female
- Genetic Therapy
- Insulin/blood
- Insulin/metabolism
- Insulin Resistance
- Insulin Secretion
- Insulin-Secreting Cells/immunology
- Insulin-Secreting Cells/metabolism
- Insulin-Secreting Cells/pathology
- Klotho Proteins
- Male
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice, 129 Strain
- Mice, Inbred ICR
- Mice, Inbred NOD
- Mice, Mutant Strains
- Phosphorylation
- Promoter Regions, Genetic
- Protein Processing, Post-Translational
- Recombinant Proteins/metabolism
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Affiliation(s)
- Yi Lin
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Zhongjie Sun
- Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK
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35
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Hsu JY, Chang KY, Chen SH, Lee CT, Chang ST, Cheng HC, Chang WC, Chen BK. Epidermal growth factor-induced cyclooxygenase-2 enhances head and neck squamous cell carcinoma metastasis through fibronectin up-regulation. Oncotarget 2015; 6:1723-39. [PMID: 25595899 PMCID: PMC4359327 DOI: 10.18632/oncotarget.2783] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/19/2014] [Indexed: 12/31/2022] Open
Abstract
Epidermal growth factor receptor (EGFR) activation is a major cause of metastasis in many cancers, such as head and neck squamous cell carcinoma (HNSCC). However, whether the induction of cyclooxygenase-2 (COX-2) mediates EGF-enhanced HNSCC metastasis remains unclear. Interestingly, we found that EGF induced COX-2 expression mainly in HNSCC. The tumor cell transformation induced by EGF was repressed by COX-2 knockdown, and this repression was reversed by simultaneously treating the cells with EGF and prostaglandin E2 (PGE2). The down-regulation of COX-2 expression or inhibition of COX-2 activity significantly blocked EGF enhancement of cell migration and invasion, but the addition of PGE2 compensated for this inhibitory effect in COX-2-knockdown cells. COX-2 depletion inhibited EGF-induced matrix metalloproteinase (MMP)-1, MMP-2, MMP-3, MMP-9, and fibronectin expression and Rac1/cdc42 activation. The inhibitory effect of COX-2 depletion on MMPs and the fibronectin/Rac1/cdc42 axis were reversed by co-treatment with PGE2. Furthermore, depletion of fibronectin impeded the COX-2-enhanced binding of HNSCC cells to endothelial cells and tumor cells metastatic seeding of the lungs. These results demonstrate that EGF-induced COX-2 expression enhances HNSCC metastasis via activation of the fibronectin signaling pathway. The inhibition of COX-2 expression and activation may be a potential strategy for the treatment of EGFR-mediated HNSCC metastasis.
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Affiliation(s)
- Jinn-Yuan Hsu
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan, ROC
| | - Kwang-Yu Chang
- National Institute of Cancer Research, National Health Research Institutes and Division of Hematology/Oncology, Department of Internal Medicine, National Cheng Kung University, Tainan 701, Taiwan, ROC
| | - Shang-Hung Chen
- Division of Hematology and Oncology, Department of Internal Medicine, Chi-Mei Medical Center, Liouying, Tainan 736, Taiwan, ROC
| | - Chung-Ta Lee
- Department of Pathology, National Cheng Kung University Hospital, Tainan 701, Taiwan, ROC
| | - Sheng-Tsung Chang
- Department of Pathology, Chi-Mei Medical Center, Tainan 710, Taiwan, ROC
| | - Hung-Chi Cheng
- Institute of Biochemistry, National Cheng Kung University, Tainan 701, Taiwan, ROC
| | - Wen-Chang Chang
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 110, Taiwan, ROC
| | - Ben-Kuen Chen
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 110, Taiwan, ROC.,Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan, ROC.,Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan, ROC
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36
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Rütti S, Howald C, Arous C, Dermitzakis E, Halban PA, Bouzakri K. IL-13 improves beta-cell survival and protects against IL-1beta-induced beta-cell death. Mol Metab 2015; 5:122-131. [PMID: 26909320 PMCID: PMC4735661 DOI: 10.1016/j.molmet.2015.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 12/25/2022] Open
Abstract
Objectives IL-13 is a cytokine classically produced by anti-inflammatory T-helper-2 lymphocytes; it is decreased in the circulation of type 2 diabetic patients and impacts positively on liver and skeletal muscle. Although IL-13 can exert positive effects on beta-cell lines, its impact and mode of action on primary beta-cell function and survival remain largely unexplored. Methods Beta-cells were cultured for 48 h in the presence of IL-13 alone or in combination with IL-1β or cytokine cocktail (IL-1β, IFNγ, TNFα). Results IL-13 protected human and rat beta-cells against cytokine induced death. However, IL-13 was unable to protect from IL-1β impaired glucose stimulated insulin secretion and did not influence NFκB nuclear relocalization induced by IL-1β. IL-13 induced phosphorylation of Akt, increased IRS2 protein expression and counteracted the IL-1β induced regulation of several beta-cell stress response genes. Conclusions The prosurvival effects of IL-13 thus appear to be mediated through IRS2/Akt signaling with NFκB independent regulation of gene expression. In addition to previously documented beneficial effects on insulin target tissues, these data suggest that IL-13 may be useful for treatment of type 2 diabetes by preserving beta-cell mass or slowing its rate of decline. IL-13 decreases human beta-cells apoptosis. IL-13 protects primary beta-cells form cytokine induced apoptosis. The IRS2/akt pathway mediates IL-13 protective effects. IL-13 modulates the expression of genes involved in stress response.
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Affiliation(s)
- Sabine Rütti
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland.
| | - Cédric Howald
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
| | - Caroline Arous
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
| | - Emmanouil Dermitzakis
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
| | - Philippe A Halban
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
| | - Karim Bouzakri
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
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37
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Arous C, Halban PA. The skeleton in the closet: actin cytoskeletal remodeling in β-cell function. Am J Physiol Endocrinol Metab 2015; 309:E611-20. [PMID: 26286869 DOI: 10.1152/ajpendo.00268.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/11/2015] [Indexed: 01/13/2023]
Abstract
Over the last few decades, biomedical research has considered not only the function of single cells but also the importance of the physical environment within a whole tissue, including cell-cell and cell-extracellular matrix interactions. Cytoskeleton organization and focal adhesions are crucial sensors for cells that enable them to rapidly communicate with the physical extracellular environment in response to extracellular stimuli, ensuring proper function and adaptation. The involvement of the microtubular-microfilamentous cytoskeleton in secretion mechanisms was proposed almost 50 years ago, since when the evolution of ever more sensitive and sophisticated methods in microscopy and in cell and molecular biology have led us to become aware of the importance of cytoskeleton remodeling for cell shape regulation and its crucial link with signaling pathways leading to β-cell function. Emerging evidence suggests that dysfunction of cytoskeletal components or extracellular matrix modification influences a number of disorders through potential actin cytoskeleton disruption that could be involved in the initiation of multiple cellular functions. Perturbation of β-cell actin cytoskeleton remodeling could arise secondarily to islet inflammation and fibrosis, possibly accounting in part for impaired β-cell function in type 2 diabetes. This review focuses on the role of actin remodeling in insulin secretion mechanisms and its close relationship with focal adhesions and myosin II.
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Affiliation(s)
- Caroline Arous
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
| | - Philippe A Halban
- Department of Genetic Medicine and Development, University of Geneva Medical Center, Geneva, Switzerland
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38
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Tennant BR, Chen J, Shih AZL, Luciani DS, Hoffman BG. Myt3 Mediates Laminin-V/Integrin-β1-Induced Islet-Cell Migration via Tgfbi. Mol Endocrinol 2015; 29:1254-68. [PMID: 26177052 PMCID: PMC5414683 DOI: 10.1210/me.2014-1387] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 07/10/2015] [Indexed: 12/17/2022] Open
Abstract
Myt3 is a prosurvival factor in pancreatic islets; however, its role in islet-cell development is not known. Here, we demonstrate that myelin transcription factor 3 (Myt3) is expressed in migrating islet cells in the developing and neonatal pancreas and thus sought to determine whether Myt3 plays a role in this process. Using an ex vivo model of islet-cell migration, we demonstrate that Myt3 suppression significantly inhibits laminin-V/integrin-β1-dependent α- and β-cell migration onto 804G, and impaired 804G-induced F-actin and E-cadherin redistribution. Exposure of islets to proinflammatory cytokines, which suppress Myt3 expression, had a similar effect, whereas Myt3 overexpression partially rescued the migratory ability of the islet cells. We show that loss of islet-cell migration, due to Myt3 suppression or cytokine exposure, is independent of effects on islet-cell survival or proliferation. Myt3 suppression also had no effect on glucose-induced calcium influx, F-actin remodeling or insulin secretion by β-cells. RNA-sequencing (RNA-seq) analysis of transduced islets showed that Myt3 suppression results in the up-regulation of Tgfbi, a secreted diabetogenic factor thought to impair cellular adhesion. Exposure of islets to exogenous transforming growth factor β-induced (Tgfbi) impaired islet-cell migration similar to Myt3 suppression. Taken together, these data suggest a model by which cytokine-induced Myt3 suppression leads to Tgfbi de-repression and subsequently to impaired islet-cell migration, revealing a novel role for Myt3 in regulating islet-cell migration.
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Affiliation(s)
- Bryan R Tennant
- Child and Family Research Institute (B.R.T., J.C., A.Z.L.S., D.S.L., B.G.H.), British Columbia Children's Hospital and Sunny Hill Health Centre, Vancouver, British Columbia, Canada V5Z 4H4; and Department of Surgery (D.S.L., B.G.H.), University of British Columbia, Vancouver, British Columbia, Canada V5Z 4E3
| | - Jenny Chen
- Child and Family Research Institute (B.R.T., J.C., A.Z.L.S., D.S.L., B.G.H.), British Columbia Children's Hospital and Sunny Hill Health Centre, Vancouver, British Columbia, Canada V5Z 4H4; and Department of Surgery (D.S.L., B.G.H.), University of British Columbia, Vancouver, British Columbia, Canada V5Z 4E3
| | - Alexis Z L Shih
- Child and Family Research Institute (B.R.T., J.C., A.Z.L.S., D.S.L., B.G.H.), British Columbia Children's Hospital and Sunny Hill Health Centre, Vancouver, British Columbia, Canada V5Z 4H4; and Department of Surgery (D.S.L., B.G.H.), University of British Columbia, Vancouver, British Columbia, Canada V5Z 4E3
| | - Dan S Luciani
- Child and Family Research Institute (B.R.T., J.C., A.Z.L.S., D.S.L., B.G.H.), British Columbia Children's Hospital and Sunny Hill Health Centre, Vancouver, British Columbia, Canada V5Z 4H4; and Department of Surgery (D.S.L., B.G.H.), University of British Columbia, Vancouver, British Columbia, Canada V5Z 4E3
| | - Brad G Hoffman
- Child and Family Research Institute (B.R.T., J.C., A.Z.L.S., D.S.L., B.G.H.), British Columbia Children's Hospital and Sunny Hill Health Centre, Vancouver, British Columbia, Canada V5Z 4H4; and Department of Surgery (D.S.L., B.G.H.), University of British Columbia, Vancouver, British Columbia, Canada V5Z 4E3
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Justus CR, Yang LV. GPR4 decreases B16F10 melanoma cell spreading and regulates focal adhesion dynamics through the G13/Rho signaling pathway. Exp Cell Res 2015; 334:100-13. [PMID: 25845498 DOI: 10.1016/j.yexcr.2015.03.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 03/02/2015] [Accepted: 03/26/2015] [Indexed: 12/15/2022]
Abstract
The effect of acidosis, a biochemical hallmark of the tumor microenvironment, on cancer progression and metastasis is complex. Both pro- and anti-tumorigenic effects of acidosis have been reported and the acidic microenvironment has been exploited for specific delivery of drugs, imaging agents, and genetic constructs into tumors. In this study we investigate the spreading and focal adhesion of B16F10 melanoma cells that are genetically engineered to overexpress the pH-sensing G protein-coupled receptor GPR4. By using cell attachment assays we found that GPR4 overexpression delayed cell spreading and altered the spatial localization of dynamic focal adhesion complex, such as the localization of phosphorylated focal adhesion kinase (FAK) and paxillin, at acidic pH. The potential G-protein and downstream signaling pathways that are responsible for these effects were also investigated. By using the Rho inhibitor CT04 (C3 transferase), the Rho-associated kinase (ROCK) inhibitors Y27632 and thiazovivin, the myosin light chain kinase (MLCK) inhibitor staurosporine or a G12/13 inhibitory construct, cell spreading was restored whereas the inhibition and activation of the Gq and Gs pathways had little or no effect. Altogether our results indicate that through the G12/13/Rho signaling pathway GPR4 modulates focal adhesion dynamics and reduces cell spreading and membrane ruffling.
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Affiliation(s)
- Calvin R Justus
- Department of Internal Medicine, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Li V Yang
- Department of Internal Medicine, Brody School of Medicine, East Carolina University, Greenville, NC, USA; Department of Oncology, Brody School of Medicine, East Carolina University, Greenville, NC, USA; Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, NC, USA.
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40
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Iorio V, Festa M, Rosati A, Hahne M, Tiberti C, Capunzo M, De Laurenzi V, Turco MC. BAG3 regulates formation of the SNARE complex and insulin secretion. Cell Death Dis 2015; 6:e1684. [PMID: 25766323 PMCID: PMC4385931 DOI: 10.1038/cddis.2015.53] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 01/24/2015] [Accepted: 01/27/2015] [Indexed: 01/07/2023]
Abstract
Insulin release in response to glucose stimulation requires exocytosis of insulin-containing granules. Glucose stimulation of beta cells leads to focal adhesion kinase (FAK) phosphorylation, which acts on the Rho family proteins (Rho, Rac and Cdc42) that direct F-actin remodeling. This process requires docking and fusion of secretory vesicles to the release sites at the plasma membrane and is a complex mechanism that is mediated by SNAREs. This transiently disrupts the F-actin barrier and allows the redistribution of the insulin-containing granules to more peripheral regions of the β cell, hence facilitating insulin secretion. In this manuscript, we show for the first time that BAG3 plays an important role in this process. We show that BAG3 downregulation results in increased insulin secretion in response to glucose stimulation and in disruption of the F-actin network. Moreover, we show that BAG3 binds to SNAP-25 and syntaxin-1, two components of the t-SNARE complex preventing the interaction between SNAP-25 and syntaxin-1. Upon glucose stimulation BAG3 is phosphorylated by FAK and dissociates from SNAP-25 allowing the formation of the SNARE complex, destabilization of the F-actin network and insulin release.
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Affiliation(s)
- V Iorio
- Department of Pharmacy, University of Salerno, via Giovanni Paolo II, 132, Fisciano, SA, Italy
| | - M Festa
- 1] Department of Pharmacy, University of Salerno, via Giovanni Paolo II, 132, Fisciano, SA, Italy [2] BIOUNIVERSA S.r.l., University of Salerno, via Giovanni Paolo II, 132, Fisciano, SA, Italy
| | - A Rosati
- 1] Department of Pharmacy, University of Salerno, via Giovanni Paolo II, 132, Fisciano, SA, Italy [2] BIOUNIVERSA S.r.l., University of Salerno, via Giovanni Paolo II, 132, Fisciano, SA, Italy
| | - M Hahne
- Institut de Génétique Moléculaire de Montpellier, CNRS UMR5535, Montpellier, France
| | - C Tiberti
- Department of Clinical Sciences, University of Rome Sapienza, Rome, Italy
| | - M Capunzo
- Department of Medicine and Surgery, University of Salerno, Via S. Allende, Baronissi, SA, Italy
| | - V De Laurenzi
- 1] BIOUNIVERSA S.r.l., University of Salerno, via Giovanni Paolo II, 132, Fisciano, SA, Italy [2] Department of Experimental and Clinical Sciences, University G. D'Annunzio and Fondazione G. D'Annunzio, Ce.S.I., Chieti, Italy
| | - M C Turco
- 1] BIOUNIVERSA S.r.l., University of Salerno, via Giovanni Paolo II, 132, Fisciano, SA, Italy [2] Department of Medicine and Surgery, University of Salerno, Via S. Allende, Baronissi, SA, Italy
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Ferreira SM, Santos GJ, Rezende LF, Gonçalves LM, Santos-Silva JC, Bigarella CL, Carneiro EM, Saad STO, Boschero AC, Barbosa-Sampaio HC. ARHGAP21 prevents abnormal insulin release through actin rearrangement in pancreatic islets from neonatal mice. Life Sci 2015; 127:53-8. [PMID: 25744409 DOI: 10.1016/j.lfs.2015.01.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 01/06/2015] [Accepted: 01/26/2015] [Indexed: 12/31/2022]
Abstract
AIMS ARHGAP21 is a Rho GTPase-activating protein (RhoGAP) that associates with many proteins and modulates several cellular functions, including actin cytoskeleton rearrangement in different tissues. However, it is unknown whether ARHGAP21 is expressed in pancreatic beta cells and its function in these cells. Herein, we assess the participation of ARHGAP21 in insulin secretion. MAIN METHODS Neonatal mice were treated with anti-sense oligonucleotide against ARHG AP21 (AS) for 2 days, resulting in a reduction of the protein's expression of about 60% in the islets. F-actin depolimerization, insulin secretion,mRNA level of genes involved in insulin secretion, maturation and proliferation were evaluated in islets from both control and AS-treated mice. KEY FINDINGS ARHGAP21 co-localized with actin inMIN6 beta cells and with insulin in neonatal pancreatic islets. F-actin was reduced in AS-islets, as judged by lower phalloidin intensity. Insulin secretion was increased in islets from AS-treated mice, however no differences were observed in the GSIS (glucose-stimulated insulin secretion). In these islets, the pERK1/2 was increased, as well as the gene expressions of VAMP2 and SNAP25, proteins that are present in the secretory machinery. Maturation and cell proliferation were not affected in islets from AS-treated mice. SIGNIFICANCE In conclusion, our data show, for the first time, that ARHGAP21 is expressed and participates in the secretory process of pancreatic beta cells. Its effect is probably via pERK1/2, which modulates the rearrangement of the cytoskeleton. ARHGAP21 also controls the expression of genes that encodes proteins of the secretory machinery.
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Affiliation(s)
- Sandra Mara Ferreira
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Gustavo Jorge Santos
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Luiz F Rezende
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Luciana Mateus Gonçalves
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Junia Carolina Santos-Silva
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Carolina Louzão Bigarella
- Department of Internal Medicine, School of Medical Science, Hematology and Hemotherapy Center - Hemocentro, INCT Sangue, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Everardo Magalhães Carneiro
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Sara Teresinha Ollala Saad
- Department of Internal Medicine, School of Medical Science, Hematology and Hemotherapy Center - Hemocentro, INCT Sangue, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Antonio Carlos Boschero
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Helena Cristina Barbosa-Sampaio
- Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
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Rondas D, Crèvecoeur I, D'Hertog W, Ferreira GB, Staes A, Garg AD, Eizirik DL, Agostinis P, Gevaert K, Overbergh L, Mathieu C. Citrullinated glucose-regulated protein 78 is an autoantigen in type 1 diabetes. Diabetes 2015; 64:573-86. [PMID: 25204978 DOI: 10.2337/db14-0621] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Posttranslational modifications of self-proteins play a substantial role in the initiation or propagation of the autoimmune attack in several autoimmune diseases, but their contribution to type 1 diabetes is only recently emerging. In the current study, we demonstrate that inflammatory stress, induced by the cytokines interleukin-1β and interferon-γ, leads to citrullination of GRP78 in β-cells. This is coupled with translocation of this endoplasmic reticulum chaperone to the β-cell plasma membrane and subsequent secretion. Importantly, expression and activity of peptidylarginine deiminase 2, one of the five enzymes responsible for citrullination and a candidate gene for type 1 diabetes in mice, is increased in islets from diabetes-prone nonobese diabetic (NOD) mice. Finally, (pre)diabetic NOD mice have autoantibodies and effector T cells that react against citrullinated GRP78, indicating that inflammation-induced citrullination of GRP78 in β-cells generates a novel autoantigen in type 1 diabetes, opening new avenues for biomarker development and therapeutic intervention.
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Affiliation(s)
- Dieter Rondas
- Laboratory for Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Inne Crèvecoeur
- Laboratory for Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Wannes D'Hertog
- Laboratory for Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | | | - An Staes
- Department of Medical Protein Research, VIB, Ghent, Belgium Department of Biochemistry, Ghent University, Ghent, Belgium
| | - Abhishek D Garg
- Laboratory for Cell Death Research and Therapy, KU Leuven, Leuven, Belgium
| | - Decio L Eizirik
- Laboratory of Experimental Medicine and Université Libre de Bruxelles Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium
| | - Patrizia Agostinis
- Laboratory for Cell Death Research and Therapy, KU Leuven, Leuven, Belgium
| | - Kris Gevaert
- Department of Medical Protein Research, VIB, Ghent, Belgium Department of Biochemistry, Ghent University, Ghent, Belgium
| | - Lut Overbergh
- Laboratory for Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Chantal Mathieu
- Laboratory for Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
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Arous C, Ferreira PG, Dermitzakis ET, Halban PA. Short term exposure of beta cells to low concentrations of interleukin-1β improves insulin secretion through focal adhesion and actin remodeling and regulation of gene expression. J Biol Chem 2015; 290:6653-69. [PMID: 25586177 DOI: 10.1074/jbc.m114.611111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type 2 diabetes involves defective insulin secretion with islet inflammation governed in part by IL-1β. Prolonged exposure of islets to high concentrations of IL-1β (>24 h, 20 ng/ml) impairs beta cell function and survival. Conversely, exposure to lower concentrations of IL-1β for >24 h improves these same parameters. The impact on insulin secretion of shorter exposure times to IL-1β and the underlying molecular mechanisms are poorly understood and were the focus of this study. Treatment of rat primary beta cells, as well as rat or human whole islets, with 0.1 ng/ml IL-1β for 2 h increased glucose-stimulated (but not basal) insulin secretion, whereas 20 ng/ml was without effect. Similar differential effects of IL-1β depending on concentration were observed after 15 min of KCl stimulation but were prevented by diazoxide. Studies on sorted rat beta cells indicated that the enhancement of stimulated secretion by 0.1 ng/ml IL-1β was mediated by the NF-κB pathway and c-JUN/JNK pathway acting in parallel to elicit focal adhesion remodeling and the phosphorylation of paxillin independently of upstream regulation by focal adhesion kinase. Because the beneficial effect of IL-1β was dependent in part upon transcription, gene expression was analyzed by RNAseq. There were 18 genes regulated uniquely by 0.1 but not 20 ng/ml IL-1β, which are mostly involved in transcription and apoptosis. These results indicate that 2 h of exposure of beta cells to a low but not a high concentration of IL-1β enhances glucose-stimulated insulin secretion through focal adhesion and actin remodeling, as well as modulation of gene expression.
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Affiliation(s)
- Caroline Arous
- From the Department of Genetic Medicine and Development, University Medical Centre, University of Geneva, 1211 Geneva 4, Switzerland
| | - Pedro G Ferreira
- From the Department of Genetic Medicine and Development, University Medical Centre, University of Geneva, 1211 Geneva 4, Switzerland
| | - Emmanouil T Dermitzakis
- From the Department of Genetic Medicine and Development, University Medical Centre, University of Geneva, 1211 Geneva 4, Switzerland
| | - Philippe A Halban
- From the Department of Genetic Medicine and Development, University Medical Centre, University of Geneva, 1211 Geneva 4, Switzerland
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Alenkvist I, Dyachok O, Tian G, Li J, Mehrabanfar S, Jin Y, Birnir B, Tengholm A, Welsh M. Absence of Shb impairs insulin secretion by elevated FAK activity in pancreatic islets. J Endocrinol 2014; 223:267-75. [PMID: 25274988 DOI: 10.1530/joe-14-0531] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The Src homology-2 domain containing protein B (SHB) has previously been shown to function as a pleiotropic adapter protein, conveying signals from receptor tyrosine kinases to intracellular signaling intermediates. The overexpression of Shb in β-cells promotes β-cell proliferation by increased insulin receptor substrate (IRS) and focal adhesion kinase (FAK) activity, whereas Shb deficiency causes moderate glucose intolerance and impaired first-peak insulin secretion. Using an array of techniques, including live-cell imaging, patch-clamping, immunoblotting, and semi-quantitative PCR, we presently investigated the causes of the abnormal insulin secretory characteristics in Shb-knockout mice. Shb-knockout islets displayed an abnormal signaling signature with increased activities of FAK, IRS, and AKT. β-catenin protein expression was elevated and it showed increased nuclear localization. However, there were no major alterations in the gene expression of various proteins involved in the β-cell secretory machinery. Nor was Shb deficiency associated with changes in glucose-induced ATP generation or cytoplasmic Ca(2+) handling. In contrast, the glucose-induced rise in cAMP, known to be important for the insulin secretory response, was delayed in the Shb-knockout compared with WT control. Inhibition of FAK increased the submembrane cAMP concentration, implicating FAK activity in the regulation of insulin exocytosis. In conclusion, Shb deficiency causes a chronic increase in β-cell FAK activity that perturbs the normal insulin secretory characteristics of β-cells, suggesting multi-faceted effects of FAK on insulin secretion depending on the mechanism of FAK activation.
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Affiliation(s)
- Ida Alenkvist
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Oleg Dyachok
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Geng Tian
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Jia Li
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Saba Mehrabanfar
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Yang Jin
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Bryndis Birnir
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Anders Tengholm
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
| | - Michael Welsh
- Department of Medical Cell BiologyUppsala University, Box 571, Husargatan 3, 75123 Uppsala, SwedenDepartment of NeuroscienceUppsala University, Uppsala, Sweden
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Abstract
From proglucagon, at least six final biologically active peptides are produced by tissue-specific post-translational processing. While glucagon and GLP-1 are the subject of permanent studies, the four others are usually left in the shadow, in spite of their large biological interest. The present review is devoted to oxyntomodulin and miniglucagon, not forgetting glicentin, although much less is known about it. Oxyntomodulin (OXM) and glicentin are regulators of gastric acid and hydromineral intestinal secretions. OXM is also deeply involved in the control of food intake and energy expenditure, properties that make this peptide a credible treatment of obesity if the question of administration is solved, as for any peptide. Miniglucagon, the C-terminal undecapeptide of glucagon which results from a secondary processing of original nature, displays properties antagonistic to that of the mother-hormone glucagon: (a) it inhibits glucose-, glucagon- and GLP-1-stimulated insulin release at sub-picomolar concentrations, (b) it reduces the in vivo insulin response to glucose with no change in glycemia, (c) it displays insulin-like properties at the cellular level using only a part of the pathway used by insulin, making it a good basis for developing a pharmacological workaround of insulin resistance.
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Affiliation(s)
| | - Stéphane Dalle
- INSERM, Research-Pathophysiology of the Pancreatic β Cell, Institute of Functional Genomic, INSERM U 661, CNRS UMR 5203, Universities Montpellier 1 & 2, Montpellier, France.
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Signaling of the p21-activated kinase (PAK1) coordinates insulin-stimulated actin remodeling and glucose uptake in skeletal muscle cells. Biochem Pharmacol 2014; 92:380-8. [PMID: 25199455 DOI: 10.1016/j.bcp.2014.08.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 08/26/2014] [Accepted: 08/28/2014] [Indexed: 11/22/2022]
Abstract
Skeletal muscle accounts for ∼ 80% of postprandial glucose clearance, and skeletal muscle glucose clearance is crucial for maintaining insulin sensitivity and euglycemia. Insulin-stimulated glucose clearance/uptake entails recruitment of glucose transporter 4 (GLUT4) to the plasma membrane (PM) in a process that requires cortical F-actin remodeling; this process is dysregulated in Type 2 Diabetes. Recent studies have implicated PAK1 as a required element in GLUT4 recruitment in mouse skeletal muscle in vivo, although its underlying mechanism of action and requirement in glucose uptake remains undetermined. Toward this, we have employed the PAK1 inhibitor, IPA3, in studies using L6-GLUT4-myc muscle cells. IPA3 fully ablated insulin-stimulated GLUT4 translocation to the PM, corroborating the observation of ablated insulin-stimulated GLUT4 accumulation in the PM of skeletal muscle from PAK1(-/-) knockout mice. IPA3-treatment also abolished insulin-stimulated glucose uptake into skeletal myotubes. Mechanistically, live-cell imaging of myoblasts expressing the F-actin biosensor LifeAct-GFP treated with IPA3 showed blunting of the normal insulin-induced cortical actin remodeling. This blunting was underpinned by a loss of normal insulin-stimulated cofilin dephosphorylation in IPA3-treated myoblasts. These findings expand upon the existing model of actin remodeling in glucose uptake, by placing insulin-stimulated PAK1 signaling as a required upstream step to facilitate actin remodeling and subsequent cofilin dephosphorylation. Active, dephosphorylated cofilin then provides the G-actin substrate for continued F-actin remodeling to facilitate GLUT4 vesicle translocation for glucose uptake into the skeletal muscle cell.
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Fractalkine (CX3CL1), a new factor protecting β-cells against TNFα. Mol Metab 2014; 3:731-41. [PMID: 25353001 PMCID: PMC4209359 DOI: 10.1016/j.molmet.2014.07.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 07/10/2014] [Accepted: 07/16/2014] [Indexed: 01/04/2023] Open
Abstract
Objective We have previously shown the existence of a muscle–pancreas intercommunication axis in which CX3CL1 (fractalkine), a CX3C chemokine produced by skeletal muscle cells, could be implicated. It has recently been shown that the fractalkine system modulates murine β-cell function. However, the impact of CX3CL1 on human islet cells especially regarding a protective role against cytokine-induced apoptosis remains to be investigated. Methods Gene expression was determined using RNA sequencing in human islets, sorted β- and non-β-cells. Glucose-stimulated insulin secretion (GSIS) and glucagon secretion from human islets was measured following 24 h exposure to 1–50 ng/ml CX3CL1. GSIS and specific protein phosphorylation were measured in rat sorted β-cells exposed to CX3CL1 for 48 h alone or in the presence of TNFα (20 ng/ml). Rat and human β-cell apoptosis (TUNEL) and rat β-cell proliferation (BrdU incorporation) were assessed after 24 h treatment with increasing concentrations of CX3CL1. Results Both CX3CL1 and its receptor CX3CR1 are expressed in human islets. However, CX3CL1 is more expressed in non-β-cells than in β-cells while its receptor is more expressed in β-cells. CX3CL1 decreased human (but not rat) β-cell apoptosis. CX3CL1 inhibited human islet glucagon secretion stimulated by low glucose but did not impact human islet and rat sorted β-cell GSIS. However, CX3CL1 completely prevented the adverse effect of TNFα on GSIS and on molecular mechanisms involved in insulin granule trafficking by restoring the phosphorylation (Akt, AS160, paxillin) and expression (IRS2, ICAM-1, Sorcin, PCSK1) of key proteins involved in these processes. Conclusions We demonstrate for the first time that human islets express and secrete CX3CL1 and CX3CL1 impacts them by decreasing glucagon secretion without affecting insulin secretion. Moreover, CX3CL1 decreases basal apoptosis of human β-cells. We further demonstrate that CX3CL1 protects β-cells from the adverse effects of TNFα on their function by restoring the expression and phosphorylation of key proteins of the insulin secretion pathway.
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Possible protective effect of membrane lipid rafts against interleukin-1β-mediated anti-proliferative effect in INS-1 cells. PLoS One 2014; 9:e102889. [PMID: 25068701 PMCID: PMC4113211 DOI: 10.1371/journal.pone.0102889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 06/20/2014] [Indexed: 12/15/2022] Open
Abstract
We recently reported that pancreatic islets from pre-diabetic rats undergo an inflammatory process in which IL-1β takes part and controls β-cell function. In the present study, using the INS-1 rat pancreatic β-cell line, we investigated the potential involvement of membrane-associated cholesterol-enriched lipid rafts in IL-1β signaling and biological effects on insulin secretion, β-cell proliferation and apoptosis. We show that, INS-1 cells exposure to increasing concentrations of IL-1β leads to a progressive inhibition of insulin release, an increase in the number of apoptotic cells and a dose-dependent decrease in pancreatic β-cell proliferation. Disruption of membrane lipid rafts markedly reduced glucose-stimulated insulin secretion but did not affect either cell apoptosis or proliferation rate, demonstrating that membrane lipid raft integrity is essential for β-cell secretory function. In the same conditions, IL-1β treatment of INS-1 cells led to a slight further decrease in insulin secretion for low concentrations of the cytokine, and a more marked one, similar to that observed in normal cells for higher concentrations. These effects occurred together with an increase in iNOS expression and surprisingly with an upregulation of tryptophane hydroxylase and protein Kinase C in membrane lipid rafts suggesting that compensatory mechanisms develop to counteract IL-1β inhibitory effects. We also demonstrate that disruption of membrane lipid rafts did not prevent cytokine-induced cell death recorded after exposure to high IL-1β concentrations. Finally, concerning cell proliferation, we bring strong evidence that membrane lipid rafts exert a protective effect against IL-1β anti-proliferative effect, possibly mediated at least partly by modifications in ERK and PKB expression/activities. Our results 1) demonstrate that IL-1β deleterious effects do not require a cholesterol-dependent plasma membrane compartmentalization of IL-1R1 signaling and 2) confer to membrane lipid rafts integrity a possible protective function that deserves to be considered in the context of inflammation and especially T2D pathogenesis.
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Yoder SM, Dineen SL, Wang Z, Thurmond DC. YES, a Src family kinase, is a proximal glucose-specific activator of cell division cycle control protein 42 (Cdc42) in pancreatic islet β cells. J Biol Chem 2014; 289:11476-11487. [PMID: 24610809 DOI: 10.1074/jbc.m114.559328] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Second-phase insulin secretion sustains insulin release in the face of hyperglycemia associated with insulin resistance, requiring the continued mobilization of insulin secretory granules to the plasma membrane. Cdc42, the small Rho family GTPase recognized as the proximal glucose-specific trigger to elicit second-phase insulin secretion, signals downstream to activate the p21-activated kinase (PAK1), which then signals to Raf-1/MEK/ERK to induce filamentous actin (F-actin) remodeling, to ultimately mobilize insulin granules to the plasma membrane. However, the steps required to initiate Cdc42 activation in a glucose-specific manner in β cells have remained elusive. Toward this, we identified the involvement of the Src family kinases (SFKs), based upon the ability of SFK inhibitors to block glucose-stimulated Cdc42 and PAK1 activation events as well as the amplifying pathway of glucose-stimulated insulin release, in MIN6 β cells. Indeed, subsequent studies performed in human islets revealed that SFK phosphorylation was induced only by glucose and within 1 min of stimulation before the activation of Cdc42 at 3 min. Furthermore, pervanadate treatment validated the phosphorylation event to be tyrosine-specific. Although RT-PCR showed β cells to express five different SFK proteins, only two of these, YES and Fyn kinases, were found localized to the plasma membrane, and of these two, only YES kinase underwent glucose-stimulated tyrosine phosphorylation. Immunodetection and RNAi analyses further established YES kinase as a proximal glucose-specific signal in the Cdc42-signaling cascade. Identification of YES kinase provides new insight into the mechanisms underlying the sustainment of insulin secretion via granule mobilization/replenishment and F-actin remodeling.
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Affiliation(s)
- Stephanie M Yoder
- Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Stacey L Dineen
- Department of Cellular and Integrative Physiology, and Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Zhanxiang Wang
- Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Debbie C Thurmond
- Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Cellular and Integrative Physiology, and Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202.
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Di Camillo B, Sambo F, Toffolo G, Cobelli C. ABACUS: an entropy-based cumulative bivariate statistic robust to rare variants and different direction of genotype effect. ACTA ACUST UNITED AC 2013; 30:384-91. [PMID: 24292361 DOI: 10.1093/bioinformatics/btt697] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
MOTIVATION In the past years, both sequencing and microarray have been widely used to search for relations between genetic variations and predisposition to complex pathologies such as diabetes or neurological disorders. These studies, however, have been able to explain only a small fraction of disease heritability, possibly because complex pathologies cannot be referred to few dysfunctional genes, but are rather heterogeneous and multicausal, as a result of a combination of rare and common variants possibly impairing multiple regulatory pathways. Rare variants, though, are difficult to detect, especially when the effects of causal variants are in different directions, i.e. with protective and detrimental effects. RESULTS Here, we propose ABACUS, an Algorithm based on a BivAriate CUmulative Statistic to identify single nucleotide polymorphisms (SNPs) significantly associated with a disease within predefined sets of SNPs such as pathways or genomic regions. ABACUS is robust to the concurrent presence of SNPs with protective and detrimental effects and of common and rare variants; moreover, it is powerful even when few SNPs in the SNP-set are associated with the phenotype. We assessed ABACUS performance on simulated and real data and compared it with three state-of-the-art methods. When ABACUS was applied to type 1 and 2 diabetes data, besides observing a wide overlap with already known associations, we found a number of biologically sound pathways, which might shed light on diabetes mechanism and etiology. AVAILABILITY AND IMPLEMENTATION ABACUS is available at http://www.dei.unipd.it/∼dicamill/pagine/Software.html.
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Affiliation(s)
- Barbara Di Camillo
- Department of Information Engineering, University of Padova, via Gradenigo 6B, 35131 Padova, Italy
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