Effects of insulin and insulin-like growth factor-I on renin gene expression in the renal cortical cells of ovine fetuses.
Renin gene expression and insulin-like growth factor-I (IGFI) gene expression are both developmentally upregulated in the renal cortex of ovine fetuses and decline after birth. The infusion of IGFI into ovine fetuses in late gestation increases plasma renin activity and concentration. In order to determine whether there are direct effects of IGFI or insulin on renin gene expression in the kidneys of ovine fetuses, we treated the renal cortical cells of ovine fetuses with IGFI or insulin. The results showed that the responses of renal renin mRNA to IGFI or insulin treatment in vitro were dependent on the culture conditions. Renin mRNA levels were significantly elevated by IGFI or insulin if the cells were cultured in medium devoid of serum (starved) for 16-18 h before treatment. In contrast, no obvious changes in renal renin mRNA expression were observed in the cells cultured in the presence of serum (non starved) before treatment with IGFI or insulin. IGFI and insulin also significantly enhanced cAMP concentrations in the medium of the cells starved in vitro. The data suggest that IGFI and insulin can act directly on the renal cortical cells from ovine fetuses to stimulate renin mRNA expression. It is possible that IGFI and insulin stimulate renin mRNA expression by increasing cAMP concentration in the cells.
Liu
J
J
Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
Rose
J C
JC
D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000032:analysis; D005333:Fetus; D015870:Gene Expression / Q000187:drug effects; D005865:Gestational Age; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007672:Kidney Cortex / Q000187:drug effects*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D012083:Renin / Q000096:biosynthesis* / Q000235:genetics; D012756:Sheep
D007328:Insulin; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D000242:Cyclic AMP; D012083:Renin