Transcriptional regulation of human Oct4 by steroidogenic factor-1.
Oct4 encodes a transcription factor that is involved in the maintenance of self-renewal in stem cells. Recently, the molecular mechanisms that regulate Oct4 expression have come under investigation. In this study, we demonstrate that the orphan nuclear receptor steroidogenic factor-1 (SF-1) behaves as a transcriptional activator of human Oct4 (hOct4) through direct interaction with a SF-1 binding element in the hOct4 proximal promoter. We found that Oct4 and SF-1 were co-expressed in undifferentiated human embryonal carcinoma NCCIT cells and downregulated during retinoic acid-mediated differentiation. We examined the functional role played by SF-1 in regulation of hOct4 transcription using a luciferase reporter assay and Western blot analysis. Overexpression of SF-1 increased up to about threefold hOct4 promoter activity and endogenous hOct4 protein expression. Sequence analysis of the hOct4 promoter revealed that the transcriptional activity was closely linked to Conserved Regions 1 (CR1) and 2 (CR2), which contain three putative SF-1-binding sites (1st, 2nd, and 3rd SF-1). Binding assays and mutagenesis of binding sites indicated that the 1st and 2nd SF-1 elements (in CR1 and CR2, respectively) might be important cis-regulatory elements in hOct4 promoter activity. However, differences in response to SF-1 overexpression between wild-type and mutant hOct4 promoters revealed that the 1st SF-1 element is the key binding site for SF-1-mediated transcriptional activation. Thus, our data indicate that SF-1 plays a crucial role in the regulation of hOct4 transcription through direct binding to the 1st SF-1 in CR1 of the hOct4 proximal promoter.
Yang
Heung-Mo
HM
Chabiotech Co. Ltd, Seoul, South Korea.
Do
Hyun-Jin
HJ
Kim
Dong-Ku
DK
Park
Jin-Ki
JK
Chang
Won-Kyong
WK
Chung
Hyung-Min
HM
Choi
Sang-Yun
SY
Kim
Jae-Hwan
JH
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D015536:Down-Regulation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D050814:Octamer Transcription Factor-3 / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054339:Steroidogenic Factor 1; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology
D018398:Homeodomain Proteins; C515057:NR5A1 protein, human; D050814:Octamer Transcription Factor-3; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D015534:Trans-Activators; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse; D014212:Tretinoin