Rapid effect of GNRH1 on follicle-stimulating hormone beta gene expression in LbetaT2 mouse pituitary cells requires the progesterone receptor.
Gonadotropin-releasing hormone (GNRH) activates the progesterone receptor (PGR) in pituitary cells and accentuates gonadotropin expression. We show that GNRH1 increases Fshb mRNA levels in LbetaT2 mouse pituitary cells within 8 h and is three times more effective than GNRH2. By contrast, GNRH1 and GNRH2 do not affect Lhb gene expression in these cells. Within the same time frame, small interfering RNA (siRNA) knockdown of the PGR in LbetaT2 cells reduced GNRH1 activation of a PGR response element (PRE)-driven luciferase reporter gene and Fshb mRNA levels by >50%. Chromatin immunoprecipitation (ChIP) assays also demonstrated that PGR loading on the PRE within the Fshb gene promoter in LbetaT2 cells occurred within 8 h after GNRH1 treatment and was lost by 24 h. While the GNRH1-induced upregulation of the PRE reporter gene and Fshb mRNA levels was attenuated by cotreatment with protein kinase A (H-89) and protein kinase C (GF109203X) inhibitors, only GF109203X inhibited PGR phosphorylation at Ser249 in LbetaT2 cells. Immunoprecipitation assays also showed a progressive increase in the interaction between the PGR and its coactivator NCOA3 that peaked at 8 h coincident with the increase in Fshb mRNA after GNRH1 treatment. The siRNA-mediated knockdown of NCOA3 in LbetaT2 cells also reduced Fshb mRNA levels after GNRH1 treatment and loading of NCOA3 on the Fshb promoter PRE in a ChIP assay. We conclude that the rapid effect of GNRH1 on Fshb expression in LbetaT2 cells is mediated by PGR phosphorylation and loading at the PRE within the Fshb promoter together with NCOA3.
An
Beum-Soo
BS
Department of Obstetrics and Gynaecology, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.
Poon
Song Ling
SL
So
Wai-Kin
WK
Hammond
Geoffrey L
GL
Leung
Peter C K
PC
D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors; D000704:Analysis of Variance; D000818:Animals; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism; D051379:Mice; D056921:Nuclear Receptor Coactivator 3 / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D011374:Progesterone / Q000008:administration & dosage; D011485:Protein Binding; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020218:Response Elements; D013997:Time Factors; D015854:Up-Regulation
D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D020033:Protein Isoforms; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011980:Receptors, Progesterone; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D056921:Nuclear Receptor Coactivator 3; D011493:Protein Kinase C; D055372:AMP-Activated Protein Kinases