Regulation of pituitary gonadotropin gene expression outline of intracellular signaling pathways.
Genes encoding pituitary gonadotropins, luteinizing hormone, and follicle-stimulating hormone, as well as their transcripts, have been isolated from different species and characterized. The position of introns in the genes is highly conserved in different species, and it appears that sequences encoding gonadotropin subunits evolved from an ancestral gene. Expression of gonadotropin genes is regulated mainly by gonadotropin-releasing hormone (GnRH) and by gonadal steroids (estradiol and testosterone). Other factors, notably thyroid hormones and gonadal peptides (follistatin, inhibin, and activin), also play a role in this regulation. Although the intracellular mechanisms of GnRH signal transduction are still unclear, now a body of evidence suggests the involvement of protein kinases C and A in intermediary steps of gonadotropin synthesis and release.
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Laboratory of Polypeptide Hormones, National Center for Scientific Research, F-91198 Gif sur Yvette, France.
Jutisz
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