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P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells
BACKGROUND/AIMS: Despite the published evidence implicating phosphoinositide 3-kinase (PI3-kinase) in the regulation of islet function, limited information is available on the putative contributory roles of its downstream signaling steps, including the phosphatidylinositol-3,4,5-trisphosphate-depend...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
2020
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9664382/ https://www.ncbi.nlm.nih.gov/pubmed/33347743 http://dx.doi.org/10.33594/000000310 |
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author | Thamilselvan, Vijayalakshmi Gamage, Suhadinie Harajli, Ali Chundru, Sri Aneesha Kowluru, Anjaneyulu |
author_facet | Thamilselvan, Vijayalakshmi Gamage, Suhadinie Harajli, Ali Chundru, Sri Aneesha Kowluru, Anjaneyulu |
author_sort | Thamilselvan, Vijayalakshmi |
collection | PubMed |
description | BACKGROUND/AIMS: Despite the published evidence implicating phosphoinositide 3-kinase (PI3-kinase) in the regulation of islet function, limited information is available on the putative contributory roles of its downstream signaling steps, including the phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor 1 (P-Rex1) signaling pathway in the islet β-cell. Therefore, we investigated potential roles for P-Rex1 in glucose-stimulated Rac1 activation and insulin secretion in insulin-secreting (INS-1 832/13) β-cells. METHODS: Glucose-stimulated Insulin secretion (GSIS) was quantified by ELISA. Expression of endogenous P-Rex1 and RhoG was suppressed by siRNA transfection using the DharmaFect1 reagent. Total membrane and cytosolic fractions were isolated using the Mem-PER Plus Membrane Extraction Kit. The degree of activation of Rac1 was determined by the pull-down assay. RESULTS: P-Rex1 is expressed in INS-1 832/13 cells, normal rat islets and human islets. siRNA-mediated knockdown of P-Rex1 attenuated glucose-induced Rac1 activation, membrane association and insulin secretion. RhoG, which has been implicated in PI3-kinase-mediated Rac1 activation in other cell types, appears not to contribute to GSIS since the siRNA-mediated knockdown of RhoG failed to exert significant effects on GSIS. LY294002, a known inhibitor of PI3-kinase, potentiated GSIS without affecting glucose-induced Rac1 activation. CONCLUSION: Based on these findings, we conclude that P-Rex1 plays a novel regulatory role in glucose-induced Rac1 activation and insulin secretion. |
format | Online Article Text |
id | pubmed-9664382 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
record_format | MEDLINE/PubMed |
spelling | pubmed-96643822022-11-14 P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells Thamilselvan, Vijayalakshmi Gamage, Suhadinie Harajli, Ali Chundru, Sri Aneesha Kowluru, Anjaneyulu Cell Physiol Biochem Article BACKGROUND/AIMS: Despite the published evidence implicating phosphoinositide 3-kinase (PI3-kinase) in the regulation of islet function, limited information is available on the putative contributory roles of its downstream signaling steps, including the phosphatidylinositol-3,4,5-trisphosphate-dependent Rac exchange factor 1 (P-Rex1) signaling pathway in the islet β-cell. Therefore, we investigated potential roles for P-Rex1 in glucose-stimulated Rac1 activation and insulin secretion in insulin-secreting (INS-1 832/13) β-cells. METHODS: Glucose-stimulated Insulin secretion (GSIS) was quantified by ELISA. Expression of endogenous P-Rex1 and RhoG was suppressed by siRNA transfection using the DharmaFect1 reagent. Total membrane and cytosolic fractions were isolated using the Mem-PER Plus Membrane Extraction Kit. The degree of activation of Rac1 was determined by the pull-down assay. RESULTS: P-Rex1 is expressed in INS-1 832/13 cells, normal rat islets and human islets. siRNA-mediated knockdown of P-Rex1 attenuated glucose-induced Rac1 activation, membrane association and insulin secretion. RhoG, which has been implicated in PI3-kinase-mediated Rac1 activation in other cell types, appears not to contribute to GSIS since the siRNA-mediated knockdown of RhoG failed to exert significant effects on GSIS. LY294002, a known inhibitor of PI3-kinase, potentiated GSIS without affecting glucose-induced Rac1 activation. CONCLUSION: Based on these findings, we conclude that P-Rex1 plays a novel regulatory role in glucose-induced Rac1 activation and insulin secretion. 2020-12-12 /pmc/articles/PMC9664382/ /pubmed/33347743 http://dx.doi.org/10.33594/000000310 Text en https://creativecommons.org/licenses/by-nc-nd/4.0/This article is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND). Usage and distribution for commercial purposes as well as any distribution of modified material requires written permission. |
spellingShingle | Article Thamilselvan, Vijayalakshmi Gamage, Suhadinie Harajli, Ali Chundru, Sri Aneesha Kowluru, Anjaneyulu P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells |
title | P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells |
title_full | P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells |
title_fullStr | P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells |
title_full_unstemmed | P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells |
title_short | P-Rex1 Mediates Glucose-Stimulated Rac1 Activation and Insulin Secretion in Pancreatic β-Cells |
title_sort | p-rex1 mediates glucose-stimulated rac1 activation and insulin secretion in pancreatic β-cells |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9664382/ https://www.ncbi.nlm.nih.gov/pubmed/33347743 http://dx.doi.org/10.33594/000000310 |
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