Ferreira Sandra Mara, Santos Gustavo Jorge, Rezende Luiz F, Gonçalves Luciana Mateus, Santos-Silva Junia Carolina, Bigarella Carolina Louzão, Carneiro Everardo Magalhães, Saad Sara Teresinha Ollala, Boschero Antonio Carlos, Barbosa-Sampaio Helena Cristina
Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
Department of Internal Medicine, School of Medical Science, Hematology and Hemotherapy Center - Hemocentro, INCT Sangue, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
Life Sci. 2015 Apr 15;127:53-8. doi: 10.1016/j.lfs.2015.01.041. Epub 2015 Mar 2.
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.
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.
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.
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.
ARHGAP21是一种Rho GTP酶激活蛋白（RhoGAP），它与许多蛋白质相互作用并调节多种细胞功能，包括不同组织中的肌动蛋白细胞骨架重排。然而，ARHGAP21是否在胰腺β细胞中表达及其在这些细胞中的功能尚不清楚。在此，我们评估ARHGAP21在胰岛素分泌中的作用。
用针对ARHGAP21的反义寡核苷酸（AS）处理新生小鼠2天，导致胰岛中该蛋白的表达降低约60%。对对照小鼠和经AS处理的小鼠的胰岛进行F-肌动蛋白解聚、胰岛素分泌、胰岛素分泌、成熟和增殖相关基因的mRNA水平评估。
ARHGAP21在MIN6β细胞中与肌动蛋白共定位，在新生胰腺胰岛中与胰岛素共定位。通过较低的鬼笔环肽强度判断，AS处理的胰岛中F-肌动蛋白减少。经AS处理的小鼠的胰岛中胰岛素分泌增加，然而在葡萄糖刺激的胰岛素分泌（GSIS）中未观察到差异。在这些胰岛中，pERK1/2增加，以及分泌机制中存在的VAMP2和SNAP25蛋白的基因表达增加。经AS处理的小鼠的胰岛中的成熟和细胞增殖未受影响。
总之，我们的数据首次表明，ARHGAP21在胰腺β细胞的分泌过程中表达并参与其中。其作用可能是通过pERK1/2，它调节细胞骨架的重排。ARHGAP21还控制编码分泌机制蛋白的基因的表达。
