FIG. 5.

Repression of MM14 differentiation by Gβγ subunits. Transient transfection of MM14 cells with vectors encoding Gβγ subunits represses myogenic differentiation induced by removal of FGF-2 (A) or by addition of PT (B). MM14 cells were cotransfected with the MSP reporter, a CMV-LacZ expression vector, and either a vector encoding Gβ1 or one encoding Gγ2. The total amount of transfected DNA in each well was equalized to 3 μg with pcDNA3 (Invitrogen). Cells were incubated in the absence or presence of FGF-2 (0.3 nM) in medium supplemented with 15% serum. (B) MM14 cells were cotransfected with the MSP reporter, the CMV-LacZ expression vector, and either 1 μg of Gβ1, 1 μg of Gγ2, or 1 μg of each for both Gβ1 and Gγ2 expression vectors. PT (192 pM) was added 6 h after transfection. For both panels, luciferase activity was determined 36 h after transfection and normalized for transfection efficiency. Luciferase activity relative to activity in cells cultured in the presence of 0.3 nM FGF-2 is shown. Mean values and standard deviations represent three (A) and two (B) independent experiments performed in triplicate.