Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA.
1] Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA [2].
Cell Death Dis. 2014 Jan 9;5(1):e986. doi: 10.1038/cddis.2013.517.
Hyperglycemia impacts different vascular cell functions and promotes the development and progression of various vasculopathies including diabetic retinopathy. Although the increased rate of apoptosis in pericytes (PCs) has been linked to increased oxidative stress and activation of protein kinase C-δ (PKC-δ) and SHP-1 (Src homology region 2 domain-containing phosphatase-1) tyrosine phosphatase during diabetes, the detailed mechanisms require further elucidation. Here we show that the rate of apoptosis and expression of proapoptotic protein Bim were increased in the retinal PCs of diabetic Akita/+ mice and mouse retinal PCs cultured under high glucose conditions. Increased Bim expression in retinal PCs under high glucose conditions required the sustained activation of signal transducer and activator of transcription 1 (STAT1) through production of inflammatory cytokines. PCs cultured under high glucose conditions also exhibited increased oxidative stress and diminished migration. Inhibition of oxidative stress, PKC-δ or Rho-associated protein kinase I/II was sufficient to protect PCs against apoptosis under high glucose conditions. Furthermore, PCs deficient in Bim expression were protected from high glucose-mediated increased oxidative stress and apoptosis. However, only inhibition of PKC-δ lowered Bim levels. N-acetylcysteine did not affect STAT1 levels, suggesting that oxidative stress is downstream of Bim. PCs cultured under high glucose conditions disrupted capillary morphogenesis of retinal endothelial cells (ECs) in coculture experiments. In addition, conditioned medium prepared from PCs under high glucose conditions attenuated EC migration. Taken together, our results indicate that Bim has a pivotal role in the dysfunction of retinal PCs under high glucose conditions by increasing oxidative stress and death of PCs.
高血糖会影响不同血管细胞的功能，并促进各种血管病变的发展和进展，包括糖尿病性视网膜病变。虽然在糖尿病中，周细胞（PCs）中细胞凋亡率的增加与氧化应激的增加以及蛋白激酶 C-δ（PKC-δ）和 Src 同源区 2 域含磷酸酶-1（SHP-1）酪氨酸磷酸酶的激活有关，但详细的机制仍需要进一步阐明。在这里，我们发现糖尿病 Akita/+ 小鼠的视网膜 PCs 和高糖培养条件下的鼠视网膜 PCs 中细胞凋亡率和促凋亡蛋白 Bim 的表达增加。高糖条件下视网膜 PCs 中 Bim 的表达增加需要通过产生炎症细胞因子来持续激活信号转导和转录激活因子 1（STAT1）。在高葡萄糖条件下培养的 PC 也表现出氧化应激增加和迁移减少。抑制氧化应激、PKC-δ 或 Rho 相关蛋白激酶 I/II 足以保护 PC 免受高葡萄糖诱导的细胞凋亡。此外，Bim 表达缺失的 PC 可防止高葡萄糖介导的氧化应激增加和细胞凋亡。然而，只有抑制 PKC-δ 才能降低 Bim 水平。N-乙酰半胱氨酸不影响 STAT1 水平，这表明氧化应激是 Bim 的下游。高糖条件下培养的 PC 破坏了视网膜内皮细胞（EC）在共培养实验中的毛细血管形态发生。此外，高糖条件下培养的 PC 产生的条件培养基减弱了 EC 的迁移。综上所述，我们的结果表明，Bim 通过增加氧化应激和 PC 的死亡，在高糖条件下对视网膜 PC 的功能障碍起关键作用。
