mRNA expression of transforming growth factor-alpha and the EGF receptor following nephrotoxic renal injury

We studied gene expression for transforming growth factor (TGF)-alpha, epid ermal growth factor (EGF), heparin binding (HB) EGF, and the EGF receptor f ollowing acute renal failure induced by mercuric chloride administration to gain insight into potential mechanisms of renal repair. Twenty four hours after HgCl2, 2 mg/kg, creatinine increased from 0.3 +/- 0.01 mg/dl in contr ols to 2.2 +/- 0.26 mg/dl in injured rats (n = 5, p < 0.01). Similar change s were observed after 3 days. Messenger RNA expression for EGF was decrease d at 24 hours in HgCl2 treated rats and remained depressed for at least 3 d ays. On the other hand steady state mRNA for TGF-alpha increased nearly 2 f old at day 3 in HgCl2 treated rats 4 mg/kg. Heparin binding EGF was increas ed early, by day one in injured kidneys and gene expression for the EGF rec eptor was increased as well. Immunohistochemistry documented an increase in expression of TGF-alpha in injured kidneys at distal nephron sites. These studies suggest that TGF-alpha along with HE EGF may be important ligands f or the EGF receptor during repair from renal injury.