Mouse oocytes suppress cAMP-induced expression of LH receptor mRNA by granulosa cells in vitro.
Mouse oocytes suppress follicle-stimulating hormone (FSH)-induced luteinizing hormone receptor (LHR) messenger ribonucleic acid (mRNA) expression in cultured granulosa cells. The objective of this study was to assess the mechanism by which oocytes suppress FSH-induced LHR expression. The effect of cumulus cell-denuded, germinal-vesicle-stage oocytes, isolated from antral follicles, on FSH-induced cyclic adenosine monophosphate (cAMP) production by cultured granulosa cells was determined by radioimmunoassays. In addition, the effect of oocytes on 8Br-cAMP-induced LHR mRNA steady-state expression by granulosa cells was assessed by RNase protection assays. Oocytes had no detectable effect on FSH-induced cAMP production. However, oocytes dramatically suppressed 8Br-cAMP-induced LHR mRNA steady-state expression by granulosa cells. It was concluded that the mechanism by which oocytes suppress FSH-induced steady-state expression of LHR mRNA is not by inactivating FSH, preventing functional interactions of FSH with its granulosa cell receptors, or by interfering with the signal-transduction mechanisms required for FSH-dependent cAMP production. In addition, since oocytes suppressed the 8Br-cAMP-induced increase in steady-state expression of mRNA for LHR, oocyte-derived factors probably suppress expression by acting downstream of FSH-induced elevation of granulosa cell cAMP.
Eppig
J J
JJ
Jackson Laboratory, Bar Harbor, Maine 04609, USA. jje@aretha.jax.org
Pendola
F L
FL
Wigglesworth
K
K
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D015870:Gene Expression; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009865:Oocytes / Q000502:physiology*; D012333:RNA, Messenger; D011974:Receptors, LH / Q000096:biosynthesis*
D012333:RNA, Messenger; D011974:Receptors, LH; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP