High Glucose-Induced TRPC6 Channel Activation Decreases Glutamate Uptake in Rat Retinal Muller Cells
High Glucose-Induced TRPC6 Channel Activation Decreases Glutamate Uptake in Rat Retinal Muller Cells
复制标题
高葡萄糖诱导的 TRPC6 通道激活减少大鼠视网膜 Muller 细胞的谷氨酸摄取
DOI：
10.3389/fphar.2019.01668
复制
发表时间：
2020-02-14
影响因子：
5.6
通讯作者：
Zheng, Zhi
中科院分区：
文献类型：
--
作者：
Ma, Mingming;Zhao, Shuzhi;Zheng, Zhi
高糖（HG）会增加活性氧（ROS）的生成，导致穆勒细胞中谷氨酸摄取减少。瞬时受体电位阳离子通道6（TRPC6）是一种对氧化应激敏感的钙离子通透阳离子通道，在穆勒细胞中易于检测到，且在高糖条件下高表达。然而，高糖诱导的穆勒细胞中TRPC6通道激活的影响尚不清楚。我们假设TRPC6通道激活介导了高糖诱导的穆勒细胞谷氨酸摄取减少。我们发现，对TRPC6通道进行RNA干扰（RNAi）可消除高糖诱导的谷氨酸摄取减少和细胞死亡。高糖还降低了谷氨酸 - 天冬氨酸转运体（GLAST）的表达，GLAST是参与谷氨酸摄取的最重要转运体。在高糖条件下，rMC - 1细胞中睫状神经营养因子（CNTF）的mRNA水平以及培养基中CNTF的释放均降低，但白细胞介素 - 6（IL - 6）和血管内皮生长因子（VEGF）的mRNA水平升高。在rMC - 1细胞中进行RNAi沉默后，CNTF的mRNA水平升高，而IL - 6和VEGF水平降低。此外，TRPC6基因敲低（KD）降低了胶质纤维酸性蛋白（GFAP）的表达，增加了内向整流钾通道4.1（Kir4.1）的表达，这表明抑制了高糖诱导的rMC - 1细胞胶质化。TRPC6基因敲低后，ROS和细胞内钙离子水平降低。暴露于高选择性TRPC6通道激动剂Hyp9（10 μM）会加重高糖诱导的病理变化。总体而言，我们的结果表明TRPC6通道激活参与了高糖诱导的rMC - 1细胞谷氨酸摄取减少。这些发现为TRPC6在高糖诱导的视网膜神经血管病变中的作用提供了新的见解，并表明TRPC6是糖尿病视网膜病变（DR）药物开发的一个有前景的靶点。
High glucose (HG) increases the production of reactive oxygen species (ROS), leading to decreased glutamate uptake in Muller cells. The transient receptor potential cation channel 6 (TRPC6) channel, an oxidative stress-sensitive Ca2+-permeable cationic channel, is readily detected in Muller cells and highly expressed under HG conditions. Yet, the effect of high glucose-induced TRPC6 channel activation in Muller cells is poorly understood. We hypothesized that TRPC6 channel activation mediates high glucose-induced decreases in Muller cell glutamate uptake. We found RNA interference (RNAi) of the TRPC6 channel abolished HG-induced decreases in glutamate uptake and cell death. HG also decreased the expression of the glutamate-aspartate transporter (GLAST), which is the most important transporter involved in glutamate uptake. The mRNA level of ciliary neurotrophic factor (CNTF) in rMC-1 cells and the release of CNTF in the culture media was decreased, but the mRNA levels of IL-6 and vascular endothelial growth factor (VEGF) were increased under HG conditions. After RNAi silencing in rMC-1 cells, the mRNA levels of CNTF increased, but IL-6 and VEGF levels decreased. Furthermore, TRPC6 knockdown (KD) decreased expression of glial fibrillary acidic protein (GFAP) and increased expression of Kir4.1, pointing to inhibition of HG-induced gliosis in rMC-1 cells. ROS and intracellular Ca2+ levels decreased after TRPC6 knockdown. Exposure to Hyp9 (10 mu M), a highly selective TRPC6 channel agonist, can aggravate HG-induced pathological changes. Collectively, our results suggest TRPC6 channel activation is involved in HG-induced decreases in glutamate uptake in rMC-1 cells. These findings provide novel insights into the role of TRPC6 in HG-induced retinal neurovasculopathy and suggest TRPC6 is a promising target for drug development for diabetic retinopathy (DR).