Insulin-like growth factor 1 modulates the phosphorylation, expression, and activity of organic anion transporter 3 through protein kinase A signaling pathway

Organic anion transporter 3 (OAT3) plays a vital role in removing a broad variety of anionic drugs from kidney,thus avoiding their possible toxicity in the body.In the current study,we investigated the role of insulin-like growth factor 1 (IGF-1) in the regulation of OAT3.We showed that IGF-1 induced a dose-and time-dependent increase in OAT3 transport activity,which correlated well with an increase in OAT3 expression.The IGF-1-induced increase in OAT3 expression was blocked by protein kinase A(PKA) inhibitor H89.Moreover,IGF-1 induced an increase in OAT3 phosphorylation,which was also blocked by H89.These data suggest that the IGF-1 modulation of OAT3 occurred through PKA signaling pathway.To further confirm the involvement of PKA,we treated OAT3-expressing cells with PKA activator Bt'2-cAMP,followed by examining OAT activity and phosphorylation.We showed that OAT3 activity and phosphorylation were much enhanced in Bt2-cAMP-treated cells as compared to that in control cells.Finally,linsitinib,an anticancer drug that blocks the IGF-1 receptor,abrogated IGF-1-stimulated OAT3 transport activity.In conclusion,our study demonstrated that IGF-1 regulates OAT3 expression and transport activity through PKA signaling pathway,possibly by phosphorylating the transporter.