PPAR-γ activation increases insulin secretion independent of CASK in INS-1 cells.
PPAR-γ activation increases insulin secretion independent of CASK in INS-1 cells.
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DOI：
10.1093/abbs/gmz052
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发表时间：
2019-07
影响因子：
3.7
通讯作者：
Kai Zhang;Qingzhao Yuan;Jinyang Xie;Li Yuan;Yao Wang
中科院分区：
文献类型：
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作者：
Kai Zhang;Qingzhao Yuan;Jinyang Xie;Li Yuan;Yao Wang
过氧化物酶体增殖物激活受体-γ (PPAR-γ) 在胰腺 β 细胞中表达，参与胰岛素分泌。然而，确切的机制仍不清楚。钙/钙调蛋白依赖性丝氨酸蛋白激酶 (CASK) 在胰岛素颗粒锚定于胰腺 β 细胞膜上发挥着至关重要的作用，可能是转录因子 PPAR-γ 的下游。本研究的目的是探讨PPAR-γ、CASK与胰岛素分泌之间的相关性。我们发现，实时聚合酶链反应（PCR）和蛋白质印迹分析显示，罗格列酮（RSG）对INS-1细胞中CASK和PPAR-γ的表达有积极影响，但免疫荧光分析显示，并没有改变CASK的细胞位置。 PPAR-γ 的敲低显着减弱了 CASK 的 mRNA 和蛋白表达水平。 ChIP-qPCR 和荧光素酶检测表明 PPAR-γ 与 Cask 启动子结合，并且 RSG 提高了 Cask 启动子的活性。 RSG 通过钾刺激显着增强胰岛素分泌，但如钾刺激胰岛素分泌测定所示，没有改变胰岛素含量。此外，通过RSG预处理，Cask的敲低并没有显着影响PPAR-γ激活介导的胰岛素分泌。此外，电子显微镜表明，与 siCask 处理的细胞相比，RSG 预处理后，Cask 沉默并没有改变锚定在细胞膜上的囊泡数量。总体而言，本研究确定 CASK 是 PPAR-γ 下游靶标之一，并且 PPAR-γ 对 INS-1 细胞中 CASK 的表达产生积极影响。 PPAR-γ 激活增加胰岛素分泌，与 CASK 的上调无关。
Peroxisome proliferator-activated receptor-γ (PPAR-γ) is expressed in pancreatic β cells and is involved in insulin secretion. However, the precise mechanisms remain unclear. Calcium/calmodulin-dependent serine protein kinase (CASK), which plays a vital role in the anchoring of insulin granules on pancreatic β cell membrane, is probably a downstream of the transcription factor PPAR-γ. The aim of the present study was to investigate the correlation among PPAR-γ, CASK and insulin secretion. We found that rosiglitazone (RSG) had a positive effect on the expression of CASK and PPAR-γ in INS-1 cells as shown by real-time polymerase chain reaction (PCR) and western blot analysis, but did not change the cellular location of CASK as shown by immunofluorescence assay. Knockdown of PPAR-γ significantly attenuated the mRNA and protein expression levels of CASK. ChIP-qPCR and luciferase assays showed that PPAR-γ bound with the Cask promoter, and promoter activity of Cask was elevated by RSG. RSG significantly enhanced the insulin secretion with potassium stimulation, but did not alter the insulin content as shown by potassium-stimulated insulin secretion assay. In addition, with RSG pretreatment, knockdown of Cask did not significantly affect the PPAR-γ activation-mediated insulin secretion. Moreover, electron microscopy demonstrated that with RSG pretreatment, silence of Cask did not change the number of vesicles anchored on the cell membranes compared with those in siCask-treated cells. Overall, the present study identifies that CASK is one of the PPAR-γ downstream targets and PPAR-γ exerts a positive effect on the expression of CASK in INS-1 cells. PPAR-γ activation increases insulin secretion independent of the upregulation of CASK.