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: The effect of dex on stomatin expression in A549 cells was investigated using RT PCR and Western blot. Cells were treated with different concentrations of dex (0.1–100 nM) for 12 hrs, or 10 nM dex for different times. As shown in Figure 2A and B, dex increased the mRNA level of stomatin in a concentration- and time-dependent manner. The level of stomatin mRNA in A549 cells treated with 10 nM dex for 8 hrs was about 3.8-fold of that in control cells (P < 0.01). Ten nanomole dex also significantly increased stomatin expression at protein level in a time-dependent fashion (Fig. 2C). The stomatin mRNA induced by dex was significantly blocked by RU486, an antagonist of GR (Fig. 3D), indicating that the effects of dex were mediated through GR.
Affiliation: Department of Pathophysiology, The Second Military Medical University, Shanghai, China.