Epidermal Growth Factor Modulates Transforming Growth Factor Receptor Messenger RNA and Protein Levels in Hamster Preantral Follicles In Vitro1

Epidermal growth factor (EGF) is mitogenic to preantral follicles, and transforming growth factor β (TGFβ) influences ovarian cell functions in a variety of species. Although an interaction of these ligands during preantral folliculogenesis is likely, whether EGF influences TGFβ action on preantral follicles by modulating TGFβ receptor (TβR) gene transcription and translation is not known. To determine whether EGF influenced TβR mRNA and protein levels in granulosa cells during preantral folliculogenesis, hamster preantral follicles at stages 1–6 were cultured in the absence or presence of EGF and follicular TβR mRNA, and protein levels were monitored by semiquantitative reverse transcription polymerase chain reaction and immunoblotting, respectively. Both TβR type I (TβRI) and TβR type II (TβRII) mRNA and protein were present in preantral follicles, and their expression was up-regulated by EGF in a stage-dependent manner. However, EGF effect on the expression of TβRI and TβRII was differential. ...