Figure 5.
IR expression in DRD1 shRNA-transfected hRPTCs. A and B, The expressions of D1R (A) and IR (B) were decreased when D1R was silenced in DRD1 shRNA-transfected hRPTCs (n = 3; *, P < .05 vs others, one-way ANOVA, Student-Newman-Keuls test). C, The ratio of p-IRS1 to t-IRS1 was decreased in DRD1 shRNA-transfected hRPTCs compared with NT and EV-transfected hRPTCs. By contrast, t-IRS expression was not affected (n = 3; *, P < .05 vs others, one-way ANOVA, Student-Newman-Keuls test). D, p-PKB expression was decreased, whereas t-PKB expression was not significantly affected in DRD1 shRNA-transfected hRPTCs compared with NT and EV-transfected hRPTCs (n = 3; *, P < .05 vs others, one-way ANOVA, Student-Newman-Keuls test). E, The ratio of p-IRS1 to t-IRS1 was increased in mock siRNA-transfected hRPTCs treated with insulin (100nM/30 min), which was also increased, but to a lesser extent, in DRD1-depleted hRPTCs treated with insulin (100nM/30 min) (n = 3; *, P < .05 vs others, one-way ANOVA, Student-Newman-Keuls test; #, P < .05, vs control treated with DRD1 siRNA, Student's t test). F, The expression of IR was decreased in DRD1 siRNA-transfected hRPTCs, as previously shown; however, insulin (100nM/30 min) had no effect on IR expression in mock or DRD1 siRNA-transfected hRPTCs (n = 3; *, P < .05 vs others, one-way ANOVA, Student-Newman-Keuls test), indicating that short-term insulin treatment does not affect IR expression. G and H, IR expression was increased by dopamine (G) or fenoldopam (H) treatment with the indicated concentrations in hRPTCs (n = 3–4; *, P < .05, vs control, one-way ANOVA, Student-Newman-Keuls test). EV, empty vector; NT, nontransfected.