Vasoactive intestinal peptide stimulates turkey prolactin gene expression by increasing transcription rate and enhancing mRNA stability.
This study evaluates the transcriptional and post-transcriptional regulation of prolactin (PRL) by vasoactive intestinal peptide (VIP). Pituitary nuclei from laying (control), incubating (with enhanced VIP secretion), and VIP-immunized laying turkey hens, and from pituitary cells cultured with or without VIP were used in nuclear run-on transcription assays. Cytoplasmic PRL mRNA was analyzed by slot blot hybridization. PRL transcription was greater in hyperprolactinemic incubating birds (PRL/beta-actin=3.33) than in laying birds (PRL/beta-actin=1.83). VIP-immunoneutralized birds had 47% and 51% decreases in PRL transcription and cytoplasmic PRL mRNA, respectively when compared with laying birds. In primary pituitary cell cultures, VIP significantly increased the transcription rate of PRL (3.8-fold) and cytoplasmic PRL mRNA (3.2-fold) compared with that of non-VIP-treated pituitary cells. The stability of pre-existing PRL mRNA was measured by Northern blot analysis after addition of actinomycin D. PRL mRNA half-lives were calculated using a two-component model, with a first-long component of 18.0+/-1.0 h and a second-short component of 3.7+/-0.7 h in non-VIP-treated pituitary cells. Both half-lives were significantly increased (53. 2+/-6.9 and 26.3+/-4.3 h) in VIP-treated cells. The present data show that VIP acts to stimulate PRL expression by up-regulating the transcription rate of PRL and by enhancing PRL mRNA stability.
Tong
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Z
Department of Animal Science, 495 Animal Science/Veterinary Medicine Building, University of Minnesota 1988 Fitch Avenue, Saint Paul, Minnesota 55108, USA.
Pitts
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You
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Foster
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El Halawani
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D000818:Animals; D002478:Cells, Cultured; D003609:Dactinomycin / Q000494:pharmacology; D004355:Drug Stability; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D007114:Immunization; D007700:Kinetics; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014422:Turkeys; D014660:Vasoactive Intestinal Peptide / Q000037:antagonists & inhibitors / Q000276:immunology / Q000494:pharmacology*
D012333:RNA, Messenger; D003609:Dactinomycin; D014660:Vasoactive Intestinal Peptide; D011388:Prolactin