Fig. 5.
The cAMP pathway up-regulates TSHR in shTRPC2 cells. A and B, In serum and hormone-starved cells, TSH-induced phosphorylation of ERK1/2 is reduced in shTRPC2 cells that overexpress PDE4D3 (n = 3; ***, P < 0.001). C and D, Reducing cAMP by overexpressing PDE4D3 decreased TSHR expression in shTRPC2 cells. The data are presented as means ± sem, n = 5; **, P < 0.01 and ***, P < 0.001. E and F, Introducing a dominant-negative form of Rap1A (Rap1A17N) into shTRPC2 cells decreases basal pERK1/2 (n = 4, P < 0.05) and TSHR to control level (n = 6, P < 0.01).