Qi Huabing, Wang Pei, Liu Chen, Li Mu, Wang Shiliang, Huang Yuesheng, Wang Fengjun
State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China.
Cell Physiol Biochem. 2011;27(3-4):251-62. doi: 10.1159/000327951. Epub 2011 Apr 1.
The mechanisms of endothelial barrier dysfunction induced by hypoxia are incompletely understood. Hypoxia-inducible factor-1 alpha (HIF-1α) is a key transcription factor partially responsible for hypoxia-related responses, but its role in regulation of hypoxia-induced endothelial barrier dysfunction is unclear. The aim of this study was to determine the molecular mechanism by which HIF-1α regulates endothelial barrier function during hypoxia. Endothelial cell monolayers exposed to normoxia or hypoxia were used for physiological, morphological, and biochemical analyses. The results showed that hypoxia disrupts endothelial barrier function by upregulating protein expression of myosin light chain (MLC) kinase (MLCK) and MLC phosphorylation. Hypoxia also induces HIF-1 activation by increasing HIF-1α expression, nuclear accumulation, DNA binding activity and target gene expression of HIF-1 in endothelial cells. Knockdown of HIF-1α attenuates endothelial barrier dysfunction and the increased MLCK protein expression induced by hypoxia. Inhibiting the transcription activity of HIF-1 by overexpressing factor inhibiting HIF-1(FIH) prevents the increased MLC phosphorylation and also attenuates endothelial barrier dysfunction in hypoxia. The results suggest that HIF-1α is involved in the MLCK-dependent endothelial barrier dysfunction induced by hypoxia.
缺氧诱导内皮屏障功能障碍的机制尚未完全明确。缺氧诱导因子-1α（HIF-1α）是一种关键转录因子，部分参与缺氧相关反应，但其在调节缺氧诱导的内皮屏障功能障碍中的作用尚不清楚。本研究旨在确定HIF-1α在缺氧期间调节内皮屏障功能的分子机制。将暴露于常氧或缺氧环境的内皮细胞单层用于生理、形态和生化分析。结果表明，缺氧通过上调肌球蛋白轻链（MLC）激酶（MLCK）的蛋白表达和MLC磷酸化来破坏内皮屏障功能。缺氧还通过增加内皮细胞中HIF-1α的表达、核积累、DNA结合活性和HIF-1的靶基因表达来诱导HIF-1激活。敲低HIF-1α可减轻缺氧诱导的内皮屏障功能障碍和MLCK蛋白表达增加。通过过表达HIF-1抑制因子（FIH）抑制HIF-1的转录活性可防止MLC磷酸化增加，并减轻缺氧时的内皮屏障功能障碍。结果表明，HIF-1α参与了缺氧诱导的依赖MLCK的内皮屏障功能障碍。
