Okuyama Y, Sowa Y, Fujita T, Mizuno T, Nomura H, Nikaido T, Endo T, Sakai T
Department of Preventive Medicine, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Japan.
FEBS Lett. 1996 Nov 18;397(2-3):219-24. doi: 10.1016/s0014-5793(96)01178-7.
RB mRNA increases during terminal differentiation of C2 myoblasts. We demonstrate that RB promoter activity increases about 4-fold during differentiation. The increase of RB promoter activity was reduced when a point mutation was designed in the ATF site. In a gel shift assay of the ATF site, two specific bands were observed. One of them, with the lower mobility, disappeared during differentiation. This band reacted with an antibody against ATF-1. We cotransfected an RB promoter-luciferase plasmid with the TREB36/ATF-1 plasmid. ATF-l suppressed the activity of the wild-type RB promoter but not of that with a point mutation at the ATF site. These results suggest that the ATF site of the RB promoter is a responsive element during myogenic differentiation of C2 cells. We hypothesize that RB promoter activity is stimulated partially due to the dissociation of ATF-1, which suppresses the promoter activity through the ATF site in C2 myoblasts.
