Effects of hypoxia-inducible factor-2α on the expression of tight junction proteins and permeability in rat glomerular endothelial cells under hypoxia condition

Objective To investigate the role of hypoxia-inducible factor-2α (HIF-2α) in the expression of tight junction proteins and permeability alterations in rat glomerular endothelial cells (rGENCs) under hypoxia condition. Methods The expressions of the HIF-2α and tight junction proteins such as occludin and ZO-1 of rGENCs were examined after exposed to 5% oxygen at different treatment time periods (0 h, 12 h, 24 h and 48 h). Then lentiviral transfection was used to knock down HIF-2α expression in rGENCs. The cells were split into four groups, including i) control group where rGENCs were cultured under normal oxygen conditions, ii) hypoxia group, iii) negative control group where rGENCs were infected with a negative vector, iv) HIF-2α lentivirus transfection group. Group ii, iii and iv were kept in hypoxic chamber (5% O2, 5% CO2 and 90% N2) for 24 h. The expressions of occludin, ZO-1 and HIF-2α were assessed by Western blotting. The permeability of rGENCs was measured using trans-epithelium electrical resistant (TEER) by Millicell® ERS voltohmmeter. Results With the elongation of hypoxia time, the expression of HIF-2α was increased gradually, while the occludin expression was decreased, there was statistically significance difference in each group (all P 0.05). And a dramatic decrease in TEER of hypoxia cells was detected as compare with control cells (P 0.05). Conclusion Hypoxia may promote HIF-2α expression, which could increase the permeability of rGENCs by reducing the expression of occludin and ZO-1. Key words: Cell hypoxia; Basic Helix-Loop-Helix transcription factors; Cell membrane permeability; Tight junction proteins; Hypoxia-inducible factor-2alpha