title: Rapid nongenomic action of aldosterone on protein expressions of Hsp90( α and β ) and pc-Src in rat kidney.
abstract: Previous in vitro studies indicated that aldosterone nongenomically phosphorylates epidermal growth factor receptor (EGFR) through activation of upstream signals, heat shock protein 90 β (Hsp90 β ), 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( α and β ) and phosphorylated (p)c-Src protein expressions. The present study further investigates the expressions of these proteins. Male Wistar rats were intraperitoneally injected with normal saline solution or aldosterone (Aldo: 150 μ g/kg BW). After 30 minutes, abundances and localizations of these proteins were determined. Aldosterone enhanced renal Hsp90 β protein abundance (P < 0.001), but Hsp90 α and pc-Src protein levels remained unaltered. Expression of Hsp90( α and β ) was induced prominently in the proximal convoluted tubules (PCTs). Activation of Hsp90 α was observed in vascular and outer medulla regions, whereas Hsp90 β 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( α and β ) 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.
authors.affiliation: Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand. eiamong@yahoo.com
authors.forename: Somchit
authors.initials: S
authors.lastname: Eiam-Ong
authors.forename: Kittisak
authors.initials: K
authors.lastname: Sinphitukkul
authors.forename: Krissanapong
authors.initials: K
authors.lastname: Manotham
authors.forename: Somchai
authors.initials: S
authors.lastname: Eiam-Ong
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D066246:ErbB Receptors / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis*; D007679:Kidney Medulla / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D018841:HSP90 Heat-Shock Proteins; D000450:Aldosterone; C483803:Egfr protein, rat; D066246:ErbB Receptors; D019061:src-Family Kinases