Steroidogenic factor-1 and the gonadotrope-specific element enhance basal and pituitary adenylate cyclase-activating polypeptide-stimulated transcription of the human glycoprotein hormone alpha-subunit gene in gonadotropes.
In the anterior pituitary, expression of the common glycoprotein hormone alpha-subunit (alphaGSU) is mediated in part by multiple response elements residing in the distal promoter (-435 bp). One such site is the gonadotrope-specific element (GSE), which is bound by the orphan nuclear receptor steroidogenic factor-1 (SF-1) and confers pituitary adenylate cyclase-activating polypeptide (PACAP)-stimulated alphaGSU expression. Here we investigated the functional importance of the GSE and SF-1 phosphorylation in both basal and stimulated alphaGSU transcription. Mutation of the GSE reduced basal and PACAP-stimulated alphaGSU promoter activity in the alphaT3-1 gonadotrope cell line. Overexpression of wild-type SF-1, but not an S203A mutant form of SF-1, enhanced basal and PACAP-stimulated alphaGSU promoter activity. The effect of PACAP on alphaGSU promoter activity was inhibited after overexpression of MAPK phosphatase. Helix assembly of the SF-1 ligand-binding domain was stimulated by PACAP in vitro via a MAPK-dependent pathway, as determined using a mammalian two-hybrid assay. PACAP quickly activated MAPK (within 5 min) and also resulted in elevated levels of phospho-cAMP response element-binding protein and phospho-SF-1, as judged by a specific antiphospho-S203 antibody; this effect was blocked by the MAPK kinase inhibitor, UO126. Collectively, these data demonstrate that SF-1 binds to the GSE and activates both basal and PACAP-stimulated alphaGSU transcription, which is further increased by phosphorylation at Ser203 via MAPK. These data suggest strongly that the induction of alphaGSU gene expression by peptide hormone signaling is coupled directly to the posttranslational status of SF-1.
Fowkes
Robert C
RC
Department of Endocrinology, Barts and Royal London School of Medicine and Dentistry, West Smithfield, London, United Kingdom. rfow0187@itsa.ucsf.edu.
Desclozeaux
Marion
M
Patel
Mayur V
MV
Aylwin
Simon J B
SJ
King
Peter
P
Ingraham
Holly A
HA
Burrin
Jacky M
JM
D000409:Alanine / Q000235:genetics; D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics*; D018398:Homeodomain Proteins; D006801:Humans; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009479:Neuropeptides / Q000378:metabolism*; D010766:Phosphorylation; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011401:Promoter Regions, Genetic / Q000235:genetics; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear; D020218:Response Elements / Q000235:genetics*; D012694:Serine / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics*
C495401:ADCYAP1 protein, human; C495402:Adcyap1 protein, mouse; D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D015292:Glycoprotein Hormones, alpha Subunit; D018398:Homeodomain Proteins; C515057:NR5A1 protein, human; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse; D012694:Serine; D000242:Cyclic AMP; D020928:Mitogen-Activated Protein Kinases; D000409:Alanine