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Cloning of the canine gene encoding transcription factor Pit-1 and its exclusion as candidate gene in a canine model of pituitary dwarfism 总被引:4,自引:0,他引:4
Irma S. Lantinga-van Leeuwen Jan A. Mol Hans S. Kooistra Ad Rijnberk Matthew Breen Corinne Renier Bernard A. van Oost 《Mammalian genome》2000,11(1):31-36
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Phylogenetic specificity of prolactin gene expression with conservation of Pit-1 function. 总被引:2,自引:0,他引:2
H P Elsholtz S Majumdar-Sonnylal F Xiong Z Gong C L Hew 《Molecular endocrinology (Baltimore, Md.)》1992,6(4):515-522
In mammals, the pituitary POU homeodomain protein, Pit-1, binds to proximal and distal 5'-flanking sequences of the PRL gene that dictate tissue-specific expression. These DNA sequences are highly conserved among mammals but are dramatically different from PRL 5' sequences in the teleost species, Oncorhynchus tschawytscha (chinook salmon). To analyze the molecular basis for pituitary-specific gene expression in a distantly related vertebrate, we transfected CAT reporter gene constructs containing 2.4 kilobases (kb) 5'-flanking sequence from the salmon PRL (sPRL) gene into various cell types. Expression of the sPRL gene was restricted to pituitary cells, but in rat pituitary GH4 cells levels of expression were at least 90-fold lower than those obtained with a -3 kb rat PRL (rPRL) construct. Conversely, in primary teleost pituitary cells, -2.4 kb sPRL/CAT was expressed at levels about 10-fold higher than -3 kb rPRL/CAT. To determine whether species-specific transactivation by Pit-1 was sufficient to explain these species differences in PRL gene expression, we isolated a cDNA clone encoding the salmon Pit-1 POU domain and constructed a rat Pit-1 expression vector that contained salmon Pit-1 POU domain sequences substituted in frame. The chimeric Pit-1 encoded 14 amino acids unique to salmon. Coexpression of rat Pit-1 with salmon or rat PRL/CAT in transfected HeLa cells resulted in specific and strikingly comparable levels of promoter activation. Moreover, the specificity and efficacy of the chimeric salmon/rat Pit-1 was similar to wild type rat Pit-1 in activating salmon and rat PRL/CAT.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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B Peers P Monget M A Nalda M L Voz M Berwaer A Belayew J A Martial 《The Journal of biological chemistry》1991,266(27):18127-18134
To identify the cis-acting elements responsible for cAMP stimulation of human prolactin (hPRL) promoter activity, pituitary GC cells were transfected with 5'-deleted hPRL promoters fused to the chloramphenicol acetyltransferase reporter gene. The proximal regulatory region (coordinates -250 to -42) was sufficient to confer strong cAMP stimulation (+/- 25 fold). Further 5' and 3' deletions performed within this proximal region demonstrated that two types of cis-acting elements are involved in the cAMP regulation: (i) the binding sites of the pituitary-specific factor Pit-1, and (ii) the sequence between coordinates -115 and -85 (named fragment A), which contains a TGACG motif. We show by gel-shift and Southwestern experiments that fragment A binds Pit-1 monomer and also a ubiquitous factor that is neither cAMP-responsive element-binding protein nor activator protein-1. Strong cAMP induction was observed when fragment A was juxtaposed to a Pit-1 binding site. That Pit-1 plays an important role was supported further by the finding that the hPRL proximal region conferred cAMP regulation when linked to the herpes simplex virus thymidine kinase promoter only in pituitary GC cells and not in other heterologous cells, which do not express Pit-1. Furthermore, we observed that concatenated Pit-1 binding sites were able to confer cAMP responsiveness to the thymidine kinase promoter in GC cells. 相似文献
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Both estrogen receptor (ER) and Pit-1 proteins are essential for the estrogen-activated expression of the rat prolactin gene. Our results show that ER.Pit-1 protein complex formation is reduced by estrogen in GH3 and PR1 rat pituitary tumor cells. In the latter, this decrease was blocked by cycloheximide, a protein synthesis inhibitor. On the other hand, the direct addition of estrogen to PR1 cell lysates had no effect on the formation of ER.Pit-1 complexes. Estrogen-activated prolactin gene expression was also inhibited by cycloheximide, suggesting that some form of protein synthesis is involved in ER.Pit-1 complex formation and subsequent prolactin gene activation. In support of this notion, we showed that estrogen-induced regulation of ER.Pit-1 complex formation could be transferred from cell lysates prepared from estrogen-treated PR1 cells to control cell lysates. This is not true for GH3 cells; instead, direct administration of estrogen to GH3 cell lysates readily abolished ER.Pit-1 protein complex formation in a dose-dependent manner, and such estrogen-induced regulation was blocked by the antiestrogen ICI 182,780. These findings thus indicate that 1) interaction between ER and Pit-1 proteins is estrogen-regulated in ways specific to different cell types, and 2) auxiliary protein factor synthesis may be involved in this process. 相似文献
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