Bit1-a novel regulator of astrocyte function during retinal development: proliferation, migration, and paracrine effects on vascular endothelial cell

Bit1 is involved in regulation between integrin and TGFβ signaling in lens epithelial cells

Bit1, as an integrin-specific effector, is specifically expressed in lens epithelial cells (LECs) and may be essential to maintain the normal function of LECs. The present study investigated the function of Bit1 and its regulatory mechanism in LECs. Knockdown of Bit1 was mediated by a lentivirus with a specific short-hairpin RNA against Bit1 in SRA01/04 cells. Cell proliferation ability was measured by CCK-8 assay. Cell migration was examined by transwell and wound-healing assays. The effect of Bit1 knockdown on genome-wide expression patterns was studied via a GeneChip® PrimeView™ Human Gene Expression Array. Based on the ingenuity pathway analysis (IPA), Bit1's regulation of target pathways and genes was verified by real-time qPCR and Western blotting. Bit1 knockdown inhibited proliferation, migration, and regulated cell cycle and apoptosis of LECs. Microarray gene expression analysis and IPA assays revealed that integrin and TGFβ signaling pathways were remarkably impacted by Bit1 expression. FAK, PAK2, ITGA5, and ITGB1 were identified as core node molecules under the control of Bit1. Bit1 participates in integrin and TGFβ signaling via regulating downstream FAK and PAK2 and subsequently affecting EMT-related gene expression including ITGA5, ITGB1, and αSMA. In conclusion, Bit1 plays as an important role in the regulation between integrin and TGFβ signaling, which affects cell survival, migration, and EMT of LECs.

Irisin Attenuates Pathological Neovascularization in Oxygen-Induced Retinopathy Mice

Purpose

Abnormal angiogenesis is a defining feature in a couple of ocular neovascular diseases. The application of anti-VEGFA therapy has achieved certain benefits in the clinic, accompanying side effects and poor responsiveness in many patients. The present study investigated the role of irisin in retinal neovascularization.

Methods

Western blot and quantitative PCR were used to determine irisin expression in the oxygen-induced retinopathy mice model. The pathological angiogenesis and inflammation index were examined after irisin administration. Primary retinal astrocytes were cultured and analyzed for VEGFA expression in vitro. Astrocyte-conditioned medium was collected for transwell assay and tube formation assay in human microvascular endothelial cells-1.

Results

Irisin was downregulated in the oxygen-induced retinopathy mice retinae. Additional irisin attenuated pathological angiogenesis, inflammation, and apoptosis in vivo. In vitro, irisin decreased astrocyte VEGFA production, and the conditioned medium suppressed human microvascular endothelial cells-1 migration. Last, irisin inhibited hypoxia-inducible factor-2α, nuclear factor-κB, and pNF-κB (Phospho-Nuclear Factor-κB) expression.

Conclusions

Irisin mitigates retinal pathological angiogenesis.

Chinese Abstract

 

目的:异常的血管生成是新生血管性眼病的显著特征。抗血管内皮生长因子A的治疗在临床上取得了一定的效果, 然而同时伴随着不可避免的副作用和不良反应。本研究旨在探讨irisin在视网膜病理性新生血管形成中的作用。

 

方法:采用免疫印迹和qPCR检测氧诱导视网膜病变小鼠模型中irisin的表达。外源性给予irisin后, 检测病理性血管生成和炎症的相关指标。为了研究irisin在体外的作用, 我们培养了原代视网膜星形胶质细胞, 检测缺氧后VEGFA的表达, 并收集星形胶质细胞的条件培养基用于人微血管内皮细胞-1(HMEC-1)的迁移和管腔形成实验。

 

结果:irisin在氧诱导视网膜病变小鼠视网膜中下调。外源性加入irisin可抑制病理性血管生成、炎症和凋亡。在体外, irisin减少星形胶质细胞中VEGFA的生成, 其处理过的星形胶质细胞条件培养基可以抑制人微血管内皮细胞-1的迁移。最后, 我们发现irisin可以降低HIF-2α、NF-κB和pNF-κB的表达水平。

 

结论:irisin可减轻视网膜病理性血管生成。