Involvement of mPOU (Brn-5), a class VI POU protein, in the gene expression of Pit-1 as well as PRL.
PRL is mainly expressed in the pituitary and its gene expression is regulated by a variety of transcription factors including Pit-1. Brn-5 is a transcription factor that binds to Pit-1 binding elements and stimulates PRL reporter gene expression. In this study, the role of Brn-5 was examined. RNA interference (RNAi) against Brn-5 leaded to reduction in PRL content of GH3 cells, indicating endogenous Brn-5 may play a role in PRL gene expression. Furthermore Brn-5 RNAi decreased Pit-1 mRNA. Transfection of expression vectors for mPOU (human ortholog of Brn-5) modestly but significantly stimulated activities of PRL-Luc and Pit-1-Luc reporter genes in GH3 and HEK 293 cells. In addition, mPOU showed synergistic action with Pit-1 and CBP on PRL-Luc expression. mPOU-FL, a splicing variant of mPOU, showed weaker activity than mPOU. Chip assay suggested binding of mPOU to PRL and Pit-1 promoters of genomic DNA. Taken together, these results suggest that mPOU (Brn-5) enhances PRL gene expression directly in association with Pit-1 and CBP, and indirectly via the activation of Pit-1 gene expression.
Toda
Keizo
K
Department of Basic Allied Medicine, Kobe University School of Medicine, 7-10-2, Tomogaoka, Suma-ku, Kobe 654-0142, Japan.
Yamamoto
Daisuke
D
Fumoto
Mariko
M
Ikeshita
Nobuko
N
Herningtyas
Elizabeth Henny
EH
Iida
Keiji
K
Takahashi
Yutaka
Y
Kaji
Hidesuke
H
Chihara
Kazuo
K
Okimura
Yasuhiko
Y
D017398:Alternative Splicing; D000818:Animals; D050882:CREB-Binding Protein / Q000378:metabolism; D002460:Cell Line; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D052682:Lactotrophs / Q000378:metabolism*; D050809:POU Domain Factors / Q000235:genetics / Q000378:metabolism*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D011388:Prolactin / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D050817:Transcription Factor Pit-1 / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D050809:POU Domain Factors; C494186:Pou1f1 protein, rat; C083853:Pou6f1 protein, rat; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D050817:Transcription Factor Pit-1; D011388:Prolactin; D050882:CREB-Binding Protein