Up-regulation of stomatin expression by hypoxia and glucocorticoid stabilizes membrane-associated actin in alveolar epithelial cells.
Bottom Line: Stomatin is an important lipid raft-associated protein which interacts with membrane proteins and plays a role in the membrane organization.In this study we found that hypoxia and dexamethasone (dex), a synthetic GC not only up-regulated the expression of stomatin alone, but also imposed additive effect on the expression of stomatin in A549 cells, primary AEC and lung of rats.Moreover, we found that hypoxia exposure did not affect membrane-associated actin, but decreased actin in cytoplasm in A549 cells.
Affiliation: Department of Pathophysiology, The Second Military Medical University, Shanghai, China.Show MeSH
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Mentions: To determine whether hypoxia or dex regulates the stomatin gene at transcriptional level, a stomatin reporter plasmid STOM (-1782 to +244)-luc containing about 2 kb (-1782 to +244) of promoter sequence of human stomatin gene was constructed and transfected into A549 cells. The reporter activity was determined by luciferase assay after cells were exposed to hypoxia or treated with dex for different times. The results showed that reporter activity did not change obviously after cells were exposed to hypoxia (Fig. 4A). However, dex induced the luciferase activity in a concentration- and time-dependent manner (Fig. 4B and C). Significant increase of reporter activity in cells treated with 100 nM dex was observed at 4 hrs with a maximal level at 36 hrs of about 2.8-fold of that in control cells (P < 0.05), indicating that dex can up-regulate stomatin expression at transcriptional level.
Affiliation: Department of Pathophysiology, The Second Military Medical University, Shanghai, China.