Functional analysis of the phenobarbital-responsive unit in rat CYP2B211Abbreviations: P450, cytochrome P450; PB, phenobarbital; CYP, P450 gene; NR, nuclear receptor; NF-1, nuclear factor-1; GRE, glucocorticoid response element; CAR, constitutive androgen receptor; RXR, retinoid X receptor; PBRU, PB response element

Mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH) is an essential component of the glycerol phosphate shuttle that transfers reduction equivalents from the cytosol into the mitochondrion. Within the testis, immunohistological analysis localized human mGPDH to late spermatids and to the midpiece of spermatozoa. The expression of human mGPDH is regulated by two somatic promoters, and here, we describe a third testis-specific promoter of human mGPDH. The usage of this testis-specific promoter correlates with the expression of a shortened mGPDH transcript of ∼2.4 kb in length, which is solely detectable from testicular RNA. Within the testis-specific promoter, we detected a cAMP-response element (CRE) site at -51, which binds the testis-specific transcriptional activator CRE modulator τ (CREMτ) in electrophoretic mobility shift assays. This recognition site overlaps with a nuclear receptor binding half-site at -49, which binds the testis-specific transcriptional repressor germ cell nuclear factor (GCNF). Both factors compete for binding to the same DNA response element. Ectopic expression of CREMτ in HepG2 cells activated a promoter-driven luciferase construct in transient transfection experiments. Additional cotransfection of GCNF relieved this activity, suggesting a down-regulation of CREMτ-mediated activation by GCNF. This effect was preserved by introducing the CRE/nuclear receptor-binding element into a heterologous promoter context. Our data suggest a down-regulation of CREMτ-mediated gene expression by GCNF, which might be a general regulation mechanism for several postmeiotically expressed genes with a temporal expression peak during early spermatid development.

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Interaction of a nuclear factor 1-like protein with a camp response element-binding protein in rat liver

International Journal of Biochemistry ◽

10.1016/0020-711x(92)90039-4 ◽

1992 ◽

Vol 24 (3) ◽

pp. 455-464 ◽

Cited By ~ 10

Author(s):

Guihua Lu ◽

Doris Schlichter ◽

Wesley D. Wicks

Keyword(s):

Rat Liver ◽

Binding Protein ◽

Camp Response Element Binding ◽

Nuclear Factor ◽

Camp Response Element ◽

Response Element ◽

Element Binding Protein ◽

Nuclear Factor 1

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Evidence that the androgen receptor mediates sexual differentiation of mouse renal cytochrome P450 expression

Biochemical Journal ◽

10.1042/bj2780499 ◽

1991 ◽

Vol 278 (2) ◽

pp. 499-503 ◽

Cited By ~ 33

Author(s):

C J Henderson ◽

C R Wolf

Keyword(s):

Cytochrome P450 ◽

Androgen Receptor ◽

Sexual Dimorphism ◽

Mammalian Species ◽

Cytochrome P450s ◽

Transcriptional Level ◽

P450 Gene ◽

P450 Expression ◽

Male Phenotype ◽

Circulating Levels

We have previously shown that sexual dimorphism in the expression of mouse renal cytochrome P450s is mediated by androgens, probably at a transcriptional level [Henderson, Scott, Yang & Wolf (1990), Biochem. J. 266, 675-681]. In the present study we show that this effect is already observed for most isoenzymes at only 2-3 weeks of age, as is the ability to induce or suppress expression with exogenous testosterone. The testosterone responsiveness did, however, exhibit age- as well as dose-dependency. Intriguingly, the effects of androgen took up to 8 days to become maximized, and the dose of testosterone needed to convert the female into the male phenotype was much higher than the circulating levels normally found in males. Studies using testicular feminized (Tfm) male mice, which carry an androgen receptor defect, showed them to have the female kidney cytochrome P450 phenotype, and these animals were not responsive to testosterone treatment. These data demonstrate the involvement of the androgen receptor in the regulation process. Taken together, our results indicate that the androgen receptor does not interact directly with the P450 genes, but initiates a cascade of events leading to the changes in cytochrome P450 gene expression. Significant differences were observed in the degree of sexual dimorphism in kidney P450 expression in other mammalian species. The significance of these findings in relation to the observed sexual dimorphism in other species is discussed.

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