Involvement of mitogen-activated protein (MAP) kinases in proliferation of quail granulosa cells in culture

The avian granulosa cells proliferate during follicular growth and differentiate to produce progesterone in response to LH, when the follicle becomes the largest. In order to study the involvement of mitogen-activated protein (MAP) kinases in proliferation of the granulosa cells in avian species, quail granulosa cells were cultured with various hormones (FSH, LH, progesterone, estradiol, testosterone) or growth factors (EGF, IGF-I, IGF-II, TGF-alpha, TGF-beta) and the presence of immunodetectable MAP kinases was examined in the cell lysates. When the granulosa cells were cultured for 72 hr with TGF-alpha, the cell number, as well as the incorporation of [H-3]thymidine was increased in a dose-dependent manner. Other hormones or growth factors caused no significant increase in cell number. Stimulation of the cells with TGF-alpha for 10 min caused a retarded mobility of immunodetectable MAP kinase in the gel of SDS-PAGE. These data suggested that the activation of MAP kinase may mediate the mitogenic action of TGF-alpha in quail granulosa cells.