Opposing actions of TGFbeta and MAP kinase signaling in undifferentiated hen granulosa cells.
The present studies were conducted to establish interactions between transforming growth factor (TGF)-beta and the epidermal growth factor (EGF) family members, TGFalpha and betacellulin (BTC), relative to proliferation and differentiation of granulosa cells in hen ovarian follicles. Results presented demonstrate expression of TGFbeta isoforms, plus TGFalpha, BTC, and ErbB receptors in prehierarchal follicles, thus establishing the potential for autocrine/paracrine signaling and cross-talk within granulosa cells at the onset of differentiation. Treatment with TGFalpha or BTC increases levels of TGFbeta1 mRNA in undifferentiated granulosa cells, while the selective inhibitor of mitogen activated protein kinase signaling, U0126, reverses these effects. Moreover, TGFbeta1 attenuates c-myc mRNA expression and granulosa cell proliferation, while TGFalpha blocks both these inhibitory effects. Collectively, these data provide evidence that EGF family ligands regulate both the expression and biological actions of TGFbeta1 in hen granulosa cells, and indicate that the timely interaction of these opposing factors is an important modulator of both granulosa cell proliferation and differentiation.
Woods
Dori C
DC
Department of Biological Sciences, The University of Notre Dame, P.O. Box 369, Notre Dame, IN 46556, USA.
Haugen
Morgan J
MJ
Johnson
A L
AL
D000818:Animals; D066259:Betacellulin; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D002645:Chickens; D004815:Epidermal Growth Factor / Q000378:metabolism*; D005260:Female; D006107:Granulosa Cells / Q000166:cytology* / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D066259:Betacellulin; D036341:Intercellular Signaling Peptides and Proteins; D016212:Transforming Growth Factor beta; D004815:Epidermal Growth Factor; D020928:Mitogen-Activated Protein Kinases