Heat shock protein 90β inhibits apoptosis of intestinal epithelial cells induced by hypoxia through stabilizing phosphorylated Akt

Abstract

Intestinal epithelial cell (IEC) apoptosis induced by hypoxiacompromise intestinal epithelium barrier function. Both Akt andHsp90 have cytoprotective function. However, the specific roleof Akt and Hsp90β in IEC apoptosis induced by hypoxia has notbeen explored. We confirmed that hypoxia-induced apoptosiswas reduced by Hsp90β overexpression but enhanced bydecreasing Hsp90β expression. Hsp90β overexpressionenhanced BAD phosphorylation and thus reduced mitochondrialrelease of cytochrome C. Reducing Hsp90β expression hadopposite effects. The protective effect of Hsp90β againstapoptosis was negated by LY294002, an Akt inhibitor. Furtherstudy showed that Akt phosphorylation was enhanced byHsp90β, which was not due to the activation of upstream PI3Kand PDK1 but because of stabilization of pAkt via directinteraction between Hsp90β and pAkt. These results demonstratethat Hsp90β may play a significant role in protecting IECs fromhypoxia-induced apoptosis via stabilizing pAkt to phosphorylateBAD and reduce cytochrome C release. [BMB Reports 2013;46(1): 47-52]

Keywords

• Apoptosis
• Caco2 cells
• Hypoxia
• Intestinal epithelial cell
• PI3K/Akt signaling pathway