- Date de publication : 1999-04-20
Tremblay JJ, Drouin J. Egr-1 is a downstream effector of GnRH and synergizes by direct interaction with Ptx1 and SF-1 to enhance luteinizing hormone beta gene transcription. Mol. Cell. Biol. 1999;19:2567-76. PubMed PMID: 10082522.
amino acid sequence animals binding sites cercopithecus aethiops dna-binding proteins early growth response protein 1 fushi tarazu transcription factors gene expression regulation gonadotropin-releasing hormone homeodomain proteins immediate-early proteins luteinizing hormone mice models, genetic molecular sequence data paired box transcription factors pituitary gland promoter regions, genetic protein binding protein kinase c receptors, cytoplasmic and nuclear signal transduction steroidogenic factor 1 transcription factors transcription, genetic
Pituitary gonadotropins are critical regulators of gonadal development and function. Expression and secretion of the mature hormones are regulated by gonadotropin-releasing hormone (GnRH), which is itself secreted from the hypothalamus. GnRH stimulation of gonadotropin expression and secretion occurs through the G-protein-linked phospholipase C/inositol triphosphate intracellular signaling pathway, which ultimately leads to protein kinase C (PKC) activation and increased intracellular calcium levels. Transcription factors mediating the effects of GnRH-induced signals on transcription of gonadotropin genes have not yet been identified. Recent studies have identified key factors involved in luteinizing hormone beta (LHbeta) gonadotropin gene transcription: the nuclear receptor SF-1, the bicoid-related homeoprotein Ptx1 (Pitx1), and the immediate-early Egr-1 gene. We now show that GnRH is a potent stimulator of Egr-1, but not Ptx1 or SF-1, expression. Further, Egr-1 activation of the LHbeta promoter is specifically enhanced by PKC, in agreement with a role for Egr-1 in mediating a GnRH effect on transcription. Egr-1 interacts directly with Ptx1 and with SF-1, leading to an enhancement of Ptx1- and SF-1-induced LHbeta transcription. Thus, Egr-1 is a likely transcriptional mediator of GnRH-induced signals for activation of the LHbeta gene.