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Abstract
Glucose-induced (physiological) insulin secretion from the islet β-cell involves interplay between cationic (i.e., changes in intracellular calcium) and metabolic (i.e., generation of hydrophobic and hydrophilic second messengers) events. A large body of evidence affirms support for novel regulation, by G proteins, of specific intracellular signaling events, including actin cytoskeletal remodeling, transport of insulin-containing granules to the plasma membrane for fusion, and secretion of insulin into the circulation. This article highlights the following aspects of GPCR-G protein biology of the islet. First, it overviews our current understanding of the identity of a wide variety of G protein regulators and their modulatory roles in GPCR-G protein-effector coupling, which is requisite for optimal β-cell function under physiological conditions. Second, it describes evidence in support of novel, noncanonical, GPCR-independent mechanisms of activation of G proteins in the islet. Third, it highlights the evidence indicating that abnormalities in G protein function lead to islet β-cell dysregulation and demise under the duress of metabolic stress and diabetes. Fourth, it summarizes observations of potential beneficial effects of GPCR agonists in preventing/halting metabolic defects in the islet β-cell under various pathological conditions (e.g., metabolic stress and inflammation). Lastly, it identifies knowledge gaps and potential avenues for future research in this evolving field of translational islet biology. Published 2020. Compr Physiol 10:453-490, 2020.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, Michigan, USA
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2
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Ferreira SM, Costa-Júnior JM, Kurauti MA, Leite NC, Ortis F, Rezende LF, Barbosa HC, Boschero AC, Santos GJ. ARHGAP21 Acts as an Inhibitor of the Glucose-Stimulated Insulin Secretion Process. Front Endocrinol (Lausanne) 2020; 11:599165. [PMID: 33324349 PMCID: PMC7726208 DOI: 10.3389/fendo.2020.599165] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 10/26/2020] [Indexed: 12/17/2022] Open
Abstract
ARHGAP21 is a RhoGAP protein implicated in the modulation of insulin secretion and energy metabolism. ARHGAP21 transient-inhibition increase glucose-stimulated insulin secretion (GSIS) in neonatal islets; however, ARHGAP21 heterozygote mice have a reduced insulin secretion. These discrepancies are not totally understood, and it might be related to functional maturation of beta cells and peripheral sensitivity. Here, we investigated the real ARHGAP21 role in the insulin secretion process using an adult mouse model of acute ARHGAP21 inhibition, induced by antisense. After ARHGAP21 knockdown induction by antisense injection in 60-day old male mice, we investigated glucose and insulin tolerance test, glucose-induced insulin secretion, glucose-induced intracellular calcium dynamics, and gene expression. Our results showed that ARHGAP21 acts negatively in the GSIS of adult islet. This effect seems to be due to the modulation of important points of insulin secretion process, such as the energy metabolism (PGC1α), Ca2+ signalization (SYTVII), granule-extrusion (SNAP25), and cell-cell interaction (CX36). Therefore, based on these finds, ARHGAP21 may be an important target in Diabetes Mellitus (DM) treatment.
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Affiliation(s)
- Sandra M. Ferreira
- Obestity and Comorbidities Research Center/Biology Institute, University State of Campinas (UNICAMP), Campinas, Brazil
| | - José M. Costa-Júnior
- Obestity and Comorbidities Research Center/Biology Institute, University State of Campinas (UNICAMP), Campinas, Brazil
| | - Mirian A. Kurauti
- Departament Physiological Sciences, University State of Maringá (UEM), Maringá, Brazil
| | - Nayara C. Leite
- Obestity and Comorbidities Research Center/Biology Institute, University State of Campinas (UNICAMP), Campinas, Brazil
| | - Fernanda Ortis
- Department of Cellular Biology and Development, Institute of Biomedical Sciences, University State of São Paulo (USP), São Paulo, Brazil
| | - Luiz F. Rezende
- Departament of Physiopathology, University State of Montes Claros (UNIMONTES), Montes Claros, Brazil
| | - Helena C. Barbosa
- Obestity and Comorbidities Research Center/Biology Institute, University State of Campinas (UNICAMP), Campinas, Brazil
| | - Antonio C. Boschero
- Obestity and Comorbidities Research Center/Biology Institute, University State of Campinas (UNICAMP), Campinas, Brazil
| | - Gustavo J. Santos
- Departament of Physiological Sciences, Center for Biological Sciences, University Federal of Santa Catarina (UFSC), Florianópolis, Brazil
- *Correspondence: Gustavo J. Santos,
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3
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Zangerolamo L, Soares GM, Vettorazzi JF, do Amaral ME, Carneiro EM, Olalla-Saad ST, Boschero AC, Barbosa-Sampaio HC. ARHGAP21 deficiency impairs hepatic lipid metabolism and improves insulin signaling in lean and obese mice. Can J Physiol Pharmacol 2019; 97:1018-1027. [PMID: 31247150 DOI: 10.1139/cjpp-2018-0691] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2023]
Abstract
ARHGAP21 is a Rho-GAP that controls GTPases activity in several tissues, but its role on liver lipid metabolism is unknown. Thus, to achieve the Rho-GAP role in the liver, control and ARHGAP21-haplodeficient mice were fed chow (Ctl and Het) or high-fat diet (Ctl-HFD and Het-HFD) for 12 weeks, and pyruvate and insulin tolerance tests, insulin signaling, liver glycogen and triglycerides content, gene and protein expression, and very-low-density lipoprotein secretion were measured. Het mice displayed reduced body weight and plasma triglycerides levels, and increased liver insulin signaling. Reduced gluconeogenesis and increased glycogen content were observed in Het-HFD mice. Gene and protein expression of microsomal triglyceride transfer protein were reduced in both Het mice, while the lipogenic genes SREBP-1c and ACC were increased. ARHGAP21 knockdown resulted in hepatic steatosis through increased hepatic lipogenesis activity coupled with decreases in CPT1a expression and very-low-density lipoprotein export. In conclusion, liver of ARHGAP21-haplodeficient mice are more insulin sensitive, associated with higher lipid synthesis and lower lipid export.
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Affiliation(s)
- Lucas Zangerolamo
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, SP, Brazil
| | - Gabriela Moreira Soares
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, SP, Brazil
| | - Jean Franciesco Vettorazzi
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, SP, Brazil
| | - Maria Esméria do Amaral
- Graduate Program in Biomedical Sciences, FHO-Herminio Ometto University Center, UNIARARAS, Araras, SP, Brazil
| | - Everardo Magalhães Carneiro
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, SP, Brazil
| | | | - Antonio Carlos Boschero
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, SP, Brazil
| | - Helena Cristina Barbosa-Sampaio
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, SP, Brazil
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Rosa LRO, Soares GM, Silveira LR, Boschero AC, Barbosa-Sampaio HCL. ARHGAP21 as a master regulator of multiple cellular processes. J Cell Physiol 2018; 233:8477-8481. [PMID: 29856495 DOI: 10.1002/jcp.26829] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 04/30/2018] [Indexed: 01/17/2023]
Abstract
The cellular cytoskeleton is involved with multiple biological processes and is tightly regulated by multiple proteins and effectors. Among these, the RhoGTPases family is one of the most important players. RhoGTPAses are, in turn, regulated by many other elements. In the past decade, one of those regulators, the RhoGAP Rho GTPase Activating Protein 21 (ARHGAP21), has been overlooked, despite being implied as having an important role on many of those processes. In this paper, we aimed to review the available literature regarding ARHGAP21 to highlight its importance and the mechanisms of action that have been found so far for this still unknown protein involved with cell adhesion, migration, Golgi regulation, cell trafficking, and even insulin secretion.
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Affiliation(s)
- Lucas R O Rosa
- Department of Structural and Functional Biology, Obesity and Comorbidities Research Center (OCRC), Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Gabriela M Soares
- Department of Structural and Functional Biology, Obesity and Comorbidities Research Center (OCRC), Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Leonardo R Silveira
- Department of Structural and Functional Biology, Obesity and Comorbidities Research Center (OCRC), Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Antonio C Boschero
- Department of Structural and Functional Biology, Obesity and Comorbidities Research Center (OCRC), Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
| | - Helena C L Barbosa-Sampaio
- Department of Structural and Functional Biology, Obesity and Comorbidities Research Center (OCRC), Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
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Soares GM, Zangerolamo L, Azevedo EG, Costa-Júnior JM, Carneiro EM, Saad ST, Boschero AC, Barbosa-Sampaio HC. Whole body ARHGAP21 reduction improves glucose homeostasis in high-fat diet obese mice. J Cell Physiol 2018; 233:7112-7119. [PMID: 29574752 DOI: 10.1002/jcp.26527] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/31/2018] [Indexed: 12/11/2022]
Abstract
GTPase activating proteins (GAPs) are ubiquitously expressed, and their role in cellular adhesion and membrane traffic processes have been well described. TBC1D1, which is a Rab-GAP, is necessary for adequate glucose uptake by muscle cells, whereas increased TCGAP, which is a Rho-GAP, decreases GLUT4 translocation, and consequently glucose uptake in adipocytes. Here, we assessed the possible involvement of ARHGAP21, a Rho-GAP protein, in glucose homeostasis. For this purpose, wild type mice and ARHGAP21 transgenic whole-body gene-deficiency mice (heterozygous mice, expressing approximately 50% of ARHGAP21) were fed either chow (Ctl and Het) or high-fat diet (Ctl-HFD and Het-HFD). Het-HFD mice showed a reduction in white fat storage, reflected in a lower body weight gain. These mice also displayed an improvement in insulin sensitivity and glucose tolerance, which likely contributed to reduced insulin secretion and pancreatic beta cell area. The reduction of body weight was also observed in Het mice and this phenomenon was associated with an increase in brown adipose tissue and reduced muscle weight, without alteration in glucose-insulin homeostasis. In conclusion, the whole body ARHGAP21 reduction improved glucose homeostasis and protected against diet-induced obesity specifically in Het-HFD mice. However, the mechanism by which ARHGAP21 leads to these outcomes requires further investigation.
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Affiliation(s)
- Gabriela M Soares
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
| | - Lucas Zangerolamo
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
| | - Elis G Azevedo
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
| | - Jose M Costa-Júnior
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
| | - Everardo M Carneiro
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
| | - Sara T Saad
- Hematology and Hemotherapy Center, University of Campinas, HEMOCENTRO-UNICAMP, Campinas, São Paulo, Brazil
| | - Antonio C Boschero
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
| | - Helena C Barbosa-Sampaio
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
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