The adaptor protein APPL2 controls glucose-stimulated insulin secretion via F-actin remodeling in pancreatic β-cells
The adaptor protein APPL2 controls glucose-stimulated insulin secretion via F-actin remodeling in pancreatic β-cells
复制标题
适配器蛋白 APPL2 通过胰腺 β 细胞中的 F 肌动蛋白重塑来控制葡萄糖刺激的胰岛素分泌。
DOI：
10.1073/pnas.2016997117
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发表时间：
2020-11-10
影响因子：
11.1
通讯作者：
Cheng, Kenneth K. Y.
中科院分区：
文献类型：
--
作者：
Wang, Baile;Lin, Huige;Cheng, Kenneth K. Y.
丝状肌动蛋白(F-Actin)细胞骨架重塑对胰岛β细胞葡萄糖刺激的胰岛素分泌(GSIS)至关重要，其失调可导致2型糖尿病。接头蛋白APPL1通过上调可溶性N-乙基马来酰亚胺敏感因子附着蛋白受体(SNARE)蛋白的表达来促进GSIS的第一阶段。然而，APPL2(APPL1与同一结构域组织的紧密同源)是否在β细胞功能中发挥作用尚不清楚。在这里，我们证明了APPL2通过促进胰岛β细胞中的小GTPase rac1的F-肌动蛋白重塑来增强GSIS。APPL2的β细胞特异性去除损伤了GSIS，导致小鼠的葡萄糖耐量减低。APPL2缺乏在很大程度上取消了葡萄糖诱导的胰岛第一时相和第二时相胰岛素分泌。实时活细胞成像和鬼臼花素染色显示，APPL2缺乏抑制了葡萄糖诱导的胰岛F-肌动蛋白解聚。同样，APPL2的表达下调也削弱了葡萄糖刺激的INS-1E细胞的F-肌动蛋白解聚和随后的胰岛素分泌，这可归因于RAS相关的C3肉毒毒素底物1(Rac1)的激活受损。用F-肌动蛋白解聚化合物或过表达明胶蛋白(一种F-肌动蛋白重塑蛋白)治疗可以挽救APPL2缺乏诱导的GSIS缺陷。此外，在INS-1E细胞和HEK293细胞中，APPL2通过APPL2的BAR-PH结构域与RAC GTPase激活蛋白1(RacGAP1)以葡萄糖依赖的方式相互作用。伴随的racGAP1表达下调逆转了APPL2缺乏诱导的INS-1E细胞GSIS缺陷、F-肌动蛋白重塑和rac1激活。我们的数据表明，APPL2与racGAP1相互作用，并抑制其对rac1活性和F-肌动蛋白解聚的负面作用，从而增强胰岛β细胞的GSIS。
Filamentous actin (F-actin) cytoskeletal remodeling is critical for glucose-stimulated insulin secretion (GSIS) in pancreatic beta-cells, and its dysregulation causes type 2 diabetes. The adaptor protein APPL1 promotes first-phase GSIS by up-regulating soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein expression. However, whether APPL2 (a close homology of APPL1 with the same domain organization) plays a role in beta-cell functions is unknown. Here, we show that APPL2 enhances GSIS by promoting F-actin remodeling via the small GTPase Rac1 in pancreatic beta-cells. beta-cell specific abrogation of APPL2 impaired GSIS, leading to glucose intolerance in mice. APPL2 deficiency largely abolished glucose-induced first- and second-phase insulin secretion in pancreatic islets. Real-time live-cell imaging and phalloidin staining revealed that APPL2 deficiency abolished glucose-induced F-actin depolymerization in pancreatic islets. Likewise, knockdown of APPL2 expression impaired glucose-stimulated F-actin depolymerization and subsequent insulin secretion in INS-1E cells, which were attributable to the impairment of Ras-related C3 botulinum toxin substrate 1 (Rac1) activation. Treatment with the F-actin depolymerization chemical compounds or overexpression of gelsolin (a F-actin remodeling protein) rescued APPL2 deficiency-induced defective GSIS. In addition, APPL2 interacted with Rac GTPase activating protein 1 (RacGAP1) in a glucose-dependent manner via the bin/amphiphysin/rvs-pleckstrin homology (BAR-PH) domain of APPL2 in INS-1E cells and HEK293 cells. Concomitant knockdown of RacGAP1 expression reverted APPL2 deficiency-induced defective GSIS, F-actin remodeling, and Rac1 activation in INS-1E cells. Our data indicate that APPL2 interacts with RacGAP1 and suppresses its negative action on Rac1 activity and F-actin depolymerization thereby enhancing GSIS in pancreatic beta-cells.