ABSTRACT
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates diverse dioxin toxicities. Despite mediating the adverse effects, the AhR gene is conserved among animal species, suggesting important physiological functions for AhR. In fact, a recent study revealed that AhR has an intrinsic function in female reproduction, though its role in male reproduction is largely unknown. In this study, we show age-dependent regression of the seminal vesicles, probably together with the coagulating gland, in AhR(-/-) male mice. Knockout mice had abnormal vaginal plugs, low sperm counts in the epididymis, and low fertility. Moreover, serum testosterone concentrations and expression of steroidogenic 3betahydroxysteroiddehydrogenase (3betaHsd) and steroidogenic acute regulatory protein (StAR) in testicular Leydig cells were decreased in AhR(-/-) males. Taken together, our results suggest that impaired testosterone synthesis in aged mice induces regression of seminal vesicles and the coagulating glands. Such tissue disappearance likely resulted in abnormal vaginal plug formation, and eventually in low fertility. Together with previous findings demonstrating AhR function in female reproduction, AhR has essential functions in animal reproduction in both sexes.
Subject(s)
Aging/physiology , Receptors, Aryl Hydrocarbon/genetics , Reproduction/physiology , Seminal Vesicles/physiology , 3-Hydroxysteroid Dehydrogenases/metabolism , Animals , Blotting, Western , Female , Immunohistochemistry , Leydig Cells/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Oligospermia/physiopathology , Phosphoproteins/metabolism , Receptors, Aryl Hydrocarbon/metabolism , Seminal Vesicles/metabolism , Testosterone/bloodABSTRACT
Two nuclear receptors, Ad4BP/SF-1 and Dax-1, are essential regulators for development and function of the mammalian reproductive system. Similarity in expression sites, such as adrenal glands, gonads, pituitary, and hypothalamus, suggests a functional interaction, and the phenotype similarities were manifested in Ad4BP/SF-1-deficient mice and in cases of natural human mutations of Dax-1. In this study, quantitative reverse transcriptase polymerase chain reaction analyses revealed that expression profiles of Dax-1 in embryonic gonads are different between the two sexes and also from those of Ad4BP/SF-1. Immunohistochemical analyses clarified the spatial and temporal expressions of the Dax-1 protein during development of tissues composing the hypothalamic-pituitary-gonadal axis. During gonadal development, Dax-1 occurred after Ad4BP/SF-1 exhibiting a sexually dimorphic expression pattern at indifferent stages, indicating a possibility of Dax-1 involvement in earliest sex differentiation. When cord formation begins in the testis at embryonic day 12.5 (E12.5), Dax-1 was expressed strongly in Sertoli cells, but its expression level markedly decreased in Sertoli cells and increased in interstitial cells between E13.5 and E17.5. In the female, Dax-1 was strongly expressed in the entire ovarian primordium from E12.5 until E14.5, and then its expression level was decreased and limited to cells near the surface epithelium between E17.5 and postnatal day 0 (P0). During postnatal development of the testis, the variable staining of Dax-1 in Sertoli cells was detected as early as P7 and Dax-1-expressing Leydig cells became rare. In the postnatal ovary, Dax-1 expression was detected in granulosa cells with variable staining intensity, and occasionally in interstitial cells. During pituitary organogenesis, Dax-1 but not Ad4BP/SF-1 was expressed in the dorsal part of Rathke's pouch from E9.5. Later in development after E14.5, the distribution of Dax-1 overlapped with that of Ad4BP/SF-1, being restricted to gonadotropic cells in the anterior pituitary. In the ventromedial hypothalamus (VMH), Dax-1 and Ad4BP/SF-1 were mostly colocalized throughout the embryonic and postnatal development. Thus, the coexpression of Dax-1 and Ad4BP/SF-1 indicates their closely related functions in the development of the reproductive system. Furthermore, we noticed the presence of cells that express Dax-1 but not Ad4BP/SF-1, further indicating additional functions of Dax-1 in an Ad4BP/SF-1-independent molecular mechanism.
Subject(s)
DNA-Binding Proteins/biosynthesis , Gonads/embryology , Hypothalamus/embryology , Pituitary Gland/embryology , Receptors, Retinoic Acid/biosynthesis , Repressor Proteins , Transcription Factors/biosynthesis , Animals , DAX-1 Orphan Nuclear Receptor , DNA, Complementary/metabolism , Female , Fushi Tarazu Transcription Factors , Homeodomain Proteins , Immunoblotting , Immunohistochemistry , Leydig Cells/metabolism , Male , Mice , Ovary/embryology , Receptors, Cytoplasmic and Nuclear , Reverse Transcriptase Polymerase Chain Reaction , Sertoli Cells/metabolism , Sex Factors , Steroidogenic Factor 1 , Testis/embryology , Time Factors , Tissue DistributionABSTRACT
Cells of Saccharomyces cerevisiae were grown aerobically and anaerobically, and levels of the protective compounds, cysteine and glutathione, and activities of defensive enzymes, catalase and superoxide dismutase, against an oxygen stress were determined and compared in both cells. Aerobiosis increased both the compounds and enzyme activities. The elevated synthesis of glutathione could be associated with the increased levels of cysteine which in its turn was found to be controlled by the oxygen-dependent activation of cystathionine beta-synthase.
Subject(s)
Oxidative Stress , Saccharomyces cerevisiae/physiology , Aerobiosis , Air , Anaerobiosis , Blotting, Northern , Blotting, Western , Catalase/metabolism , Cystathionine beta-Synthase/metabolism , Cysteine/metabolism , Enzyme Activation , Glutathione/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/growth & development , Superoxide Dismutase/metabolismABSTRACT
Multiprotein bridging factor 1 (MBF1) is a coactivator which mediates transcriptional activation by interconnecting the general transcription factor TATA element-binding protein and gene-specific activators such as the Drosophila nuclear receptor FTZ-F1 or the yeast basic leucine zipper protein GCN4. The human homolog of MBF1 (hMBF1) has been identified but its function, especially in transcription, remains unclear. Here we report the cDNA cloning and functional analysis of hMBF1. Two isoforms, which we term hMBF1alpha and hMBF1beta, have been identified. hMBF1alpha mRNA was detected in a number of tissues, whereas hMBF1beta exhibited tissue-specific expression. Both isoforms bound to TBP and Ad4BP/SF-1, a mammalian counterpart of FTZ-F1, and mediated Ad4BP/SF-1-dependent transcriptional activation. While hMBF1 was detected in the cytoplasm by immunostaining, coexpression of the nuclear protein Ad4BP/SF-1 with hMBF1 induced accumulation of hMBF1 in the nucleus, suggesting that hMBF1 is localized in the nucleus through its binding to Ad4BP/SF-1. hMBF1 also bound to ATF1, a member of the basic leucine zipper protein family, and mediated its activity as a transcriptional activator. These data establish that the coactivator MBF1 is functionally conserved in eukaryotes.
Subject(s)
Calmodulin-Binding Proteins , Drosophila Proteins , Trans-Activators/genetics , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , COS Cells , Cloning, Molecular , DNA, Complementary/chemistry , DNA, Complementary/genetics , DNA-Binding Proteins/metabolism , Female , Fluorescent Antibody Technique , Fushi Tarazu Transcription Factors , Gene Expression , HeLa Cells , Homeodomain Proteins , Humans , Leucine Zippers , Male , Molecular Sequence Data , Protein Binding , Protein Isoforms/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Cytoplasmic and Nuclear , Recombinant Fusion Proteins/analysis , Recombinant Fusion Proteins/genetics , Sequence Alignment , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Steroidogenic Factor 1 , TATA-Box Binding Protein , Tissue Distribution , Trans-Activators/metabolism , Trans-Activators/physiology , Transcription Factors/metabolism , Transcription, Genetic , Tumor Cells, CulturedABSTRACT
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.-Morohashi, K.-I., and Omura, T. Ad4BP/SF-1, a transcription factor essential for the transcription of steroidogenic cytochrome P450 genes and for the establishment of the reproductive function.
