title: Prolactin-mediated transcriptional and post-transcriptional control of casein gene expression.
abstract: The mechanism by which prolactin, a peptide hormone, regulates casein gene expression has been studied in mammary gland organ culture. After prolactin addition, a 2-4 fold increase in the rate of casein mRNA transcription was observed within 1 hr and maintained for at least 24 hr. This increased rate of transcription is not sufficient to account for the mass accumulation of casein mRNA. The half-life of casein mRNA is also increased 17-25 fold in the presence of prolactin. This change in casein mRNA half-life, coupled with a 2-4 fold increase in the rate of transcription, can account for the normal accumulation of casein mRNA observed after prolactin addition. This hormone-induced change in casein mRNA half-life appeared to be selective, since prolactin was found to exert only a slight effect (1-4 fold) on the half-life of poly(A) RNA determined under identical pulse-chase conditions. The hormonal regulation of casein gene expression thus does not app-ar to be an "all or none" process occurring only at the transcriptional or post-transcriptional levels, but rather may involve a coordinated response at several levels to permit the efficient expression of specialized differentiated functions.
mesh_terms: D000818:Animals; D002364:Caseins / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D005796:Genes; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism; D009924:Organ Culture Techniques; D011247:Pregnancy; D011388:Prolactin / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D002364:Caseins; D012333:RNA, Messenger; D011388:Prolactin