Dax1 suppresses P450arom expression in medaka ovarian follicles.
Dax1 is a member of an unusual orphan nuclear receptor family, and is known to regulate P450arom in mammals and is involved in sex differentiation in some vertebrates. To investigate whether Dax1 is involved in the regulation of the steroidogenic pathway for estrogen biosynthesis in medaka ovarian follicles, we isolated Dax1 cDNA from adult medaka ovaries and analyzed its expression pattern in medaka gonads. In adult ovaries, Dax1 mRNA was detected only in postvitellogenic follicles and was not detected in previtellogenic and vitellogenic follicles. In adult testis, Dax1 mRNA was not detected. We compared the expression pattern of Dax1 with that of Foxl2, Ad4BP/Sf-1, P450c17, and P450arom by in situ hybridization using adjacent sections. In contrast to Dax1 expression, these genes were co-expressed in vitellogenic follicles but were not detected in postvitellogenic follicles. Thus, in medaka ovarian follicles, Dax1 did not show any overlapping expression patterns against Foxl2, Ad4BP/Sf-1, P450c17, and P450arom. Moreover, co-transfection experiments demonstrated that Dax1 inhibits Ad4BP/Sf-1- and Foxl2-mediated P450arom expression. On the other hand, during early sex differentiation, Dax1 mRNA was not detected in both males and females. Our results suggest that Dax1 down-regulates Ad4BP/Sf-1- and Foxl2-mediated P450arom expression in medaka ovarian follicles.
Nakamoto
Masatoshi
M
Department of Environmental System Science, Graduate School of Science and Technology, Shinshu University, Matsumoto, Japan.
Wang
De-Shou
DS
Suzuki
Aya
A
Matsuda
Masaru
M
Nagahama
Yoshitaka
Y
Shibata
Naoki
N
D000595:Amino Acid Sequence; D000818:Animals; D001141:Aromatase / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular; D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins / Q000502:physiology*; D015536:Down-Regulation; D004625:Embryo, Nonmammalian; D005260:Female; D051858:Forkhead Transcription Factors / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009990:Oryzias / Q000196:embryology / Q000235:genetics*; D006080:Ovarian Follicle / Q000201:enzymology* / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D018168:Receptors, Retinoic Acid / Q000502:physiology*; D012097:Repressor Proteins / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D012733:Sex Differentiation / Q000235:genetics; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000235:genetics
D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins; D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; C539965:NR0B1 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D001141:Aromatase