Binding of steroidogenic factor-1 to the regulatory region might not be critical for transcriptional regulation of the human CYP1B1 gene.
Cytochrome P450 (CYP) 1B1, which catalyzes 17beta-estradiol 4-hydroxylation, is expressed in steroid-related tissues including ovary, testis, and adrenal gland. Generally, the expressions of steroidogenic CYPs are transcriptionally regulated by steroidogenic factor-1 (SF-1) and cAMP response element (CRE) binding protein (CREB). In the present study, we examined the possibility that the human CYP1B1 gene might be regulated by SF-1 and CREB. Gel shift analyses revealed that in vitro translated SF-1 can bind to the putative SF-1 binding sites, SF-1a (at -1722) and SF-1b (at -2474), on the CYP1B1 gene. In vitro translated CREB barely binds to the putative SF-1 binding sites. Luciferase analysis revealed that a reporter plasmid, pGL3 (-2623/+25), containing the SF-1a and SF-1b elements is transactivated by the concomitant co-expression of SF-1 and protein kinase A (PKA). However, the transcriptional activity is induced by PKA alone. Mutations in the SF-1a and SF-1b elements did not affect the luciferase activity. Thus, the binding of SF-1 to the putative SF-1 binding sites of the human CYP1B1 gene might not be essential for transcriptional regulation. Interestingly, deletion and mutation analyses indicated that the PKA signaling pathway is involved in the xenobiotic responsive element (XRE)-mediated transactivation of the human CYP1B1 gene.
Drug Metabolism and Toxicology, Division of Pharmaceutical Sciences, Graduate School of Medical Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192.
Yuki
Y
Tsuchiya
Miki
M
Nakajima
Shingo
S
Takagi
Miki
M
Katoh
Wenchao
W
Zheng
Colin R
CR
Jefcoate
Tsuyoshi
T
Yokoi
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D045744:Cell Line, Tumor; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology*; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D011485:Protein Binding / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000378:metabolism*
C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D018398:Homeodomain Proteins; C515057:NR5A1 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; C585498:Cyp1b1 protein, mouse; D065633:Cytochrome P-450 CYP1B1; D017868:Cyclic AMP-Dependent Protein Kinases