Ad4BP/SF-1, a transcription factor essential for the transcription of steroidogenic cytochrome P450 genes and for the establishment of the reproductive function

Ad4BP/SF-1 was identified as the steroidogenic tissue-specific transcription factor regulating the expression of the steroidogenic cytochrome P450 genes. In addition to the steroidogenic endocrine tissues such as adrenal cortex, testis, and ovary, the factor was found to be expressed in the pituitary gonadotroph and the ventromedial hypothalamic nucleus. Considering the roles of the hypothalamus-pituitary-gonadal axis, it is reasonable to assume that Ad4BP/SF-1 is closely associated with the reproductive function of adult animals. Another fundamental role of Ad4BP/SF- 1 in the fetal development was discovered by gene disruption studies. Serious structural and functional defects were observed in the Ad4BP/SF-1-positive tissues of the gene-disrupted mice. Based on the sexually dimorphic expression of Ad4BP/SF-1 in the fetal gonads, the factor is also likely to be involved in the gonadal sex differentiation. Because of this functional significance during the tissue differentiation, the regulatory mechanism of the Ad4BP/SF-1 gene, the mammalian Ftz-F1 gene, has been investigated. The gene is controlled by an autoregulatory mechanism in which Ad4BP/SF-1 functions as the dominant transcription factor.