Polycystin-1 Inhibits Cell Proliferation through Phosphatase PP2A/B56α

Figure 1

Downregulation of cell proliferation/protein translation and downstream effectors of mTOR by PC1. (a) Effects of PC1-5TMC or full-length PC1 on proliferation of HeLa and HEK293T cells. HeLa cells transiently expressing GFP-PC1-5TMC, GFP vector, and HEK293T stably expressing full-length mouse PC1 were plated in multiple wells of a 96-well plate and grown for another 24 hr for cell proliferation assay. Cell proliferation rate of control was normalized to 100%. Control (Ctrl), GFP vector; 5TMC, GFP-tagged PC1-5TMC; PC1, HEK293T cells stably expressing full-length PC1. Shown are averaged data (N = 4). (b) Effects of PC1-5TMC on proliferation of MDCK and IMCD3 cells. MDCK and IMCD3 cells replacing the above cells were transiently transfected with PC1-5TMC and GFP vector, and cell proliferation assay was performed as shown in (a) (N = 4). (c) Effects of full-length PC1 on protein synthesis. HEK293T cells stably expressing full-length PC1 were starved for 1 hr and then followed by pulse labelling for ³⁵S pulse labelling assay. (d) Effects of PC1-5TMC in HeLa cells on protein synthesis. ³⁵S pulse labelling assay of HeLa cells transiently expressing PC1-5TMC or GFP was performed as that of the above HEK293T cells in (c). (e) Effects of full-length PC1 on P-S6 and P-4EBP1. 60 μg of total protein from HEK293T cells stably expressing flag-tagged WT PC1 or GFP vector was used for WB with the indicated antibodies. β-Actin served as loading controls. (f) Statistical data showing averaged and normalized ratios (%) of P-S6/S6 (N = 4) and P-4EBP1/4EBP1 (N = 4) from (e).

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