Rapid Nongenomic Action of Aldosterone on Protein Expressions of Hsp90(α and β) and pc-Src in Rat Kidney

Previous in vitro studies indicated that aldosterone nongenomically phosphorylates epidermal growth factor receptor (EGFR) through activation of upstream signals, heat shock protein 90 beta (Hsp90 beta), and cytosolic (c)-Src kinase. We demonstrated that aldosterone rapidly elevates EGFR phosphorylation in rat kidney. There are no in vivo data regarding renal Hsp90(alpha and beta) and phosphorylated (p)c-Src protein expressions.. e present study further investigates the expressions of these proteins. Male Wistar rats were intraperitoneally injected with normal saline solution or aldosterone (Aldo: 150 mu g/kg BW). After 30 minutes, abundances and localizations of these proteins were determined. Aldosterone enhanced renal Hsp90 beta. protein abundance (p < 0.001), but Hsp90 alpha and pc-Src protein levels remained unaltered. Expression of Hsp90(alpha and beta) was induced prominently in the proximal convoluted tubules (PCTs). Activation of Hsp90 alpha was observed in vascular and outer medulla regions, whereas Hsp90 beta was induced in the cortex. Immunoreactivity of pc-Src was elevated in PCT with obvious staining at the luminal membrane. This in vivo study is the first to demonstrate that aldosterone nongenomically elevates Hsp90(alpha and beta) protein expressions in rat kidney. Aldosterone had no effect on pc-Src protein levels but modulated localization. These results indicate that aldosterone regulates upstream mediators of EGFR transactivation in vivo.