Involvement of mitogen-activated protein kinase in transforming growth factor alpha-stimulated cell proliferation in the cultured granulosa cells of the Japanese quail

The avian granulosa cells proliferate during follicular growth phase and di fferentiate to produce progesterone in response to luteinizing hormone (LH) when the follicle becomes the largest. In order to study the involvement o f mitogen-activated protein (MAP) kinase in proliferation of the granulosa cells in avian species, quail granulosa cells were cultured for 66 h with v arious hormones (follicle stimulating hormone (FSH), LH, progesterone, estr adiol-17 beta, testosterone), or growth factors (transforming growth factor alpha (TGF alpha), epidermal growth factor (EGF), insulin-like growth fact or I (IGF-I), IGF-II), and the presence of immunodetectable MAP kinase was examined in the cell lysates. When the granulosa cells were cultured with T GF alpha, the cell number as well as the incorporation of [H-3]thymidine wa s increased. Other hormones or growth factors caused no significant increas e in cell numbers. Stimulation of the cells with TGF alpha for 10 min cause d a retarded mobility of MAP kinase in the gel of SDS-PAGE. Both the increa ses in [H-3]thymidine incorporation and the retarded mobility were inhibite d by the presence of a tyrosine kinase inhibitor, genistein, indicating the importance of phosphorylation of protein during the TGF alpha-stimulation. (C) 1999 Elsevier Science Inc. All rights reserved.