The pituitary-specific transcription factor, Pit-1, can direct changes in the chromatin structure of the prolactin promoter.
The chromatin structure of a promoter is an important determinant of its transcriptional activity. Many promoters are assembled into repressive polynucleosomal arrays that are subsequently remodeled to allow for the activation of gene expression. This study addresses the contribution of a single transcription factor, Pit-1, in orchestrating the chromatin structure of the prolactin gene. Utilizing an in vivo reconstitution system, we found that Pit-1 can bind to multiple sites in the chromatin-assembled 5'-flanking region of the prolactin gene and activate transcription from the chromatin-assembled template. Interestingly, Pit-1 was able to substantially alter micrococcal nuclease digestion of the prolactin 5'-flanking region, and the results are consistent with presence of a translationally positioned nucleosome on the prolactin promoter. Changes in micrococcal nuclease digestion were also observed with a truncated Pit-1 mutant containing only the DNA-binding domain. As the truncation mutant was unable to activate transcription from the chromatin-assembled template, the ability of Pit-1 to alter chromatin structure of the prolactin gene is not dependent on transcriptional activation. We propose that Pit-1 likely plays a role in altering chromatin to facilitate recruitment and subsequent transcriptional activation by additional factors.
Kievit
Paul
P
Department of Cell and Developmental Biology, L215, Oregon Health & Science University, 3181 South West Sam Jackson Park Road, Portland, Oregon 97239, USA.
Maurer
Richard A
RA
D024506:5' Flanking Region / Q000235:genetics; D000818:Animals; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism*; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008836:Micrococcal Nuclease / Q000378:metabolism; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D011388:Prolactin / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D013997:Time Factors; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism
D002843:Chromatin; D004268:DNA-Binding Proteins; D009707:Nucleosomes; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; D011388:Prolactin; D004247:DNA; D008836:Micrococcal Nuclease