Analysis of the function of activin βC subunit using recombinant protein

Abstract

Activins, TGF-β superfamily members, have multiple functions in a variety of cells and tissues. Additional activin β subunit genes, βC and βE, have been identified in humans and rodents. To explore the role of activin βC subunit, we generated recombinant human activin C using Chinese hamster ovary cells. Recombinant activin C from the conditioned medium was purified by consecutive hydrophobic, size-exclusion, and high performance liquid chromatography. SDS-PAGE and Western blot analysis of the purified protein revealed that activin C formed disulfide bridges. However, activin C had no effect on the proliferation of cultured liver cells. Furthermore, there were no significant differences in erythroid differentiation and follicle stimulating hormone secretion in vitro. It was also shown that immunoreactive bands indicated the hetrodimer of activin βC, and inhibin α subunits were detected in the conditioned medium from the activin C-producing cells, which were stably transfected with inhibin α subunit cDNA. This suggests that activin βC subunit may have been present and that it may exert its effect as inhibin C.