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Edward R B Mccabe - One of the best experts on this subject based on the ideXlab platform.
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LXXLL motifs and AF-2 domain mediate SHP (NR0B2) homodimerization and DAX1 (NR0B1)-DAX1A heterodimerization.
Molecular Genetics and Metabolism, 2007Co-Authors: Anita K. Iyer, Yaohua Zhang, Edward R B MccabeAbstract:Abstract Small heterodimer partner (SHP; NR0B2 ) is an unusual orphan member of the nuclear receptor superfamily that functions as a corepressor of other nuclear receptors through heterodimeric interactions. Mutations in SHP are associated with mild obesity and insulin resistance. The protein domain structure of SHP is similar to Dosage-sensitive sex reversal adrenal hypoplasia congenita (AHC) critical region on the X chromosome, gene 1 (DAX1; NR0B1 ). Mutations in DAX1 cause AHC with associated hypogonadotropic hypogonadism. DAX1A is an alternatively spliced isoform of DAX1 that lacks the last 80 amino acids of the DAX1 C-terminal repressor domain and is replaced by a novel 10-amino acid motif. We have previously shown homodimerization of SHP and DAX1 individually, heterodimerization of DAX1 with SHP, and heterodimerization of DAX1 with DAX1A. In these studies, we investigated the domains and residues of SHP involved in SHP homodimerization and DAX1–SHP heterodimerization and also further characterized DAX1–DAX1 homodimerization and DAX1–DAX1A heterodimerization. We showed involvement of the SHP LXXLL motifs and AF-2 domain in SHP homodimerization and DAX1–SHP heterodimerization. We demonstrated redundancy of the LXXLL motifs in DAX1 homodimerization. While DAX1A subcellular localization is mostly cytoplasmic, DAX1–DAX1A heterodimers existed in the nucleus, suggesting differential functions for DAX1A in each compartment. We showed that the AF-2 domain of DAX1 is involved in DAX1–DAX1A heterodimerization. These results indicate that NR0B family members use similar mechanisms for homodimerization as well as heterodimerization. These resemble coactivator–receptor interactions that may have potential functional consequences for molecular mechanisms of the NR0B family.
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DAX1 increasing complexity in the roles of this novel nuclear receptor
Molecular and Cellular Endocrinology, 2007Co-Authors: Edward R B MccabeAbstract:Abstract DAX1 (NR0B1) is a nuclear receptor with a characteristic C-terminal ligand binding domain, but an atypical DNA binding domain. Mutations in the DAX1 gene cause adrenal hypoplasia congenita (AHC) establishing its biological importance. Recent studies highlight the complexities of DAX1 regulation and function. There is considerable phenotypic variability in AHC suggesting the existence of DAX1 modifier genes and environmental influences on DAX1 function. The findings of an alternatively spliced DAX1A, more common than DAX1 in all tissues except testis, of DAX1 homodimers, and of DAX1 heterodimers with a number of transcription factor partners including DAX1A and SHP point to an expanded transcription regulatory network under DAX1 control. Model organisms (mice and zebrafish) are being used to identify other DAX1 functions and modifier genes to understand the pathogenesis of AHC and the lack of genotype–phenotype correlation.
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zebrafish DAX1 is required for development of the interrenal organ the adrenal cortex equivalent
Molecular Endocrinology, 2006Co-Authors: Y Zhao, Edward R B Mccabe, Zhongan Yang, J K Phelan, D A Wheeler, Shuo LinAbstract:Mutations in the human nuclear receptor, DAX1, cause X-linked adrenal hypoplasia congenita (AHC). We report the isolation and characterization of a DAX1 homolog, DAX1, in zebrafish. The DAX1 cDNA encodes a protein of 264 amino acids, including the conserved carboxy-terminal ligand binding-like motif; but the amino-terminal region lacks the unusual repeats of the DNA binding-like domain in mammals. Genomic sequence analysis indicates that the DAX1 gene structure is conserved also. Whole-mount in situ hybridization revealed the onset of DAX1 expression in the developing hypothalamus at approximately 26 h post fertilization (hpf). Later, at about 28 hpf, a novel expression domain for DAX1 appeared in the trunk. This bilateral DAX1-expressing structure was located immediately above the yolk sac, between the otic vesicle and the pronephros. Interestingly, weak and transient expression of DAX1 was observed in the interrenal glands (adrenal cortical equivalents) at approximately 31 hpf. This gene was also expres...
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dosage sensitive sex reversal adrenal hypoplasia congenita critical region on the x chromosome gene 1 DAX1 nr0b1 and small heterodimer partner shp nr0b2 form homodimers individually as well as DAX1 shp heterodimers
Molecular Endocrinology, 2006Co-Authors: Anita K. Iyer, Yaohua Zhang, Edward R B MccabeAbstract:Dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome, gene 1 (DAX1) (NR0B1), and small heterodimer partner (SHP) (NR0B2) are atypical nuclear receptor superfamily members that function primarily as corepressors through heterodimeric interactions with other nuclear receptors. Mutations in DAX1 cause adrenal hypoplasia congenita, and mutations in SHP lead to mild obesity and insulin resistance, but the mechanisms are unclear. We investigated the existence and subcellular localization of DAX1 and SHP homodimers and the dynamics of homodimerization. We demonstrated DAX1 homodimerization in the nucleus and cytoplasm, and dissociation of DAX1 homodimers upon heterodimerization with steroidogenic factor 1 (SF1) or ligand-activated estrogen receptor-alpha (ERalpha). DAX1 homodimerization involved an interaction between its amino and carboxy termini involving its LXXLL motifs and activation function (AF)-2 domain. We observed SHP homodimerization in the nucleus of mammalian cells and showed dissociation of SHP homodimers upon heterodimerization with ligand-activated ERalpha. We observed DAX1-SHP heterodimerization in the nucleus of mammalian cells and demonstrated the involvement of the LXXLL motifs and AF-2 domain of DAX1 in this interaction. We further demonstrate heterodimerization of DAX1 with its alternatively spliced isoform, DAX1A. This is the first evidence of homodimerization of individual members of the unusual NR0B nuclear receptor family and heterodimerization between its members. Our results suggest that DAX1 forms antiparallel homodimers through the LXXLL motifs and AF-2 domain. These homodimers may function as holding reservoirs in the absence of heterodimeric partners. The formation of DAX1 and SHP homodimers and DAX1-SHP and DAX1-DAX1A heterodimers suggests the possibility of novel functions independent of their coregulator roles, suggesting additional complexity in the molecular mechanisms of DAX1 and SHP action.
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a familial missense mutation in the hinge region of DAX1 associated with late onset ahc in a prepubertal female
Molecular Genetics and Metabolism, 2006Co-Authors: Pascal Bernard, Yaohua Zhang, Edward R B Mccabe, Louisa Mabel Ludbrook, Gloria Queipo, Marybeth Dinulos, Gad B Kletter, James K Phelan, Vincent R HarleyAbstract:Mutations in the DAX1 (Dosage-sensitive sex reversal-Adrenal hypoplasia congenita (AHC) critical region on the X chromosome gene 1; NR0B1) cause X-linked AHC, a disease characterized by primary adrenal failure in infancy and hypogonadotropic hypogonadism. All known missense mutations impair DAX1 repression of steroidogenic factor 1 (SF1) transactivation and have been localized to the putative ligand binding domain. Here, an asymptomatic father and his late-onset AHC daughter were both shown to share a novel DAX1 mutation (C200W), the first missense mutation identified in the hinge region of DAX1. Using immunohistochemistry we demonstrate that the sub-cellular localization of the C200W mutant DAX1 protein is shifted from the nucleus to the cytoplasm. The disturbed localization of the C200W mutant in transfected cells correlates with impaired transcriptional repression activity. The import defect is relatively mild, retaining 80% of wild-type activity, which may explain the unusually mild phenotype. Import of DAX1 into the nucleus involves a direct interaction with SF1. In vitro assays demonstrate that the C200W mutant retains the ability to functionally interact with SF1, which suggests that SF1-independent interactions of DAX1 could be responsible for the import defect.
Vincent R Harley - One of the best experts on this subject based on the ideXlab platform.
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excess DAX1 leads to xy ovotesticular disorder of sex development dsd in mice by inhibiting steroidogenic factor 1 sf1 activation of the testis enhancer of sry box 9 sox9
Endocrinology, 2012Co-Authors: Louisa M Ludbrook, Janelle Ryan, Ryohei Sekido, Robin Lovellbadge, Dagmar Wilhelm, Stefan Bagherifam, Pascal Bernard, Vincent R HarleyAbstract:Human DAX1 duplications cause dosage-sensitive sex reversal (DSS) whereby chromosomally XY individuals can develop as females due to gonadal dysgenesis. However, the mechanism of DSS-adrenal hypoplasia congenita on X, gene 1 (DAX1) action in the fetal testis is unknown. We show that in fetal testes from XY DAX1-overexpressing transgenic mice, the expression of the key testis-promoting gene sex-determining region on Y (SRY)-box-9 (Sox9) is reduced. Moreover, in XY Sox9 heterozygotes, in which testis development is usually normal, DAX1 overexpression results in ovotestes, suggesting a DAX1-SOX9 antagonism. The ovarian portion of the XY ovotestes was characterized by expression of the granulosa cell marker, Forkhead box-L2, with complete loss of the Sertoli cell markers, SOX9 and anti-Mullerian hormone, and the Leydig cell marker CYP17A1. However, the expression of SRY and steroidogenic factor-1 (SF1), two key transcriptional regulators of Sox9, was retained in the ovarian portion of the XY ovotestes. Using ...
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excess DAX1 leads to xy ovotesticular disorder of sex development dsd in mice by inhibiting steroidogenic factor 1 sf1 activation of the testis enhancer of sry box 9 sox9
Endocrinology, 2012Co-Authors: Louisa M Ludbrook, Janelle Ryan, Ryohei Sekido, Robin Lovellbadge, Dagmar Wilhelm, Stefan Bagherifam, Pascal Bernard, Vincent R HarleyAbstract:Human DAX1 duplications cause dosage-sensitive sex reversal (DSS) whereby chromosomally XY individuals can develop as females due to gonadal dysgenesis. However, the mechanism of DSS-adrenal hypoplasia congenita on X, gene 1 (DAX1) action in the fetal testis is unknown. We show that in fetal testes from XY DAX1-overexpressing transgenic mice, the expression of the key testis-promoting gene sex-determining region on Y (SRY)-box-9 (Sox9) is reduced. Moreover, in XY Sox9 heterozygotes, in which testis development is usually normal, DAX1 overexpression results in ovotestes, suggesting a DAX1-SOX9 antagonism. The ovarian portion of the XY ovotestes was characterized by expression of the granulosa cell marker, Forkhead box-L2, with complete loss of the Sertoli cell markers, SOX9 and anti-Mullerian hormone, and the Leydig cell marker CYP17A1. However, the expression of SRY and steroidogenic factor-1 (SF1), two key transcriptional regulators of Sox9, was retained in the ovarian portion of the XY ovotestes. Using reporter mice, DAX1 overexpression reduced activation of TES, the testis enhancer of Sox9, indicating that DAX1 might repress Sox9 expression via TES. In cultured cells, increasing levels of DAX1 antagonized SF1-, SF1/SRY-, and SF1/SOX9-mediated activation of TES, due to reduced binding of SF1 to TES, providing a likely mechanism for DSS.
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177 a mechanism underlying disorders of sex development caused by DAX1 duplication
Reproduction Fertility and Development, 2009Co-Authors: Louisa M Ludbrook, Robin Lovellbadge, Vincent R Harley, R SekidoAbstract:The DAX1 protein is an orphan nuclear hormone receptor expressed in developing and adult hypothalamic, pituitary, adrenal and gonadal tissues. In humans, duplication of the DAX1 gene at locus Xp21 causes Disorders of Sex Development (DSD), whereby XY individuals develop as females, due to the failure of testicular development. DAX1 acts as a co-factor for nuclear receptor-mediated transcription of steroidogenic genes. In mice, overexpression of a DAX1 transgene causes delayed testis cord formation, a milder phenotype than that seen in human (1). Exactly how DAX1 duplication interferes with typical testicular development is unclear but a ‘window' of DAX1 activity was proposed (2). In order to identify the mechanism of DAX1 action when overexpressed in the developing XY gonad, we have used both in vivo and in vitro approaches. We hypothesised that, when present in excess, DAX1 must repress the action of early testis-forming genes. We investigated the effect of DAX1 over expression, using the DAX1 transgenic mouse line, DAX1812 (1), on expression of Sox9, a critical testis-forming gene. Immunostaining of DAX1812 gonads revealed reduced Sox9 expression, suggesting excess DAX1 antagonises Sox9 upregulation during the early stages of sex determination. To determine whether antagonism of Sox9 was occurring at the transcriptional level we assessed the effect of excess DAX1 on the activity of the Testis-Specific Enhancer of Sox9 (TES), which drives Sox9 transcription in the developing XY gonad (3). In combination, the in vivo and in vitro evidence strongly suggests that DAX1, when present in excess, can repress Sox9 expression through TES and that this repression occurs through inhibition of Steroidogenic Factor-1 activity. With this work we have identified a potential mechanism for disruption of the male-specific sex determination pathway caused by DAX1 duplication and leading to DSD in XY individuals.
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a familial missense mutation in the hinge region of DAX1 associated with late onset ahc in a prepubertal female
Molecular Genetics and Metabolism, 2006Co-Authors: Pascal Bernard, Yaohua Zhang, Edward R B Mccabe, Louisa Mabel Ludbrook, Gloria Queipo, Marybeth Dinulos, Gad B Kletter, James K Phelan, Vincent R HarleyAbstract:Mutations in the DAX1 (Dosage-sensitive sex reversal-Adrenal hypoplasia congenita (AHC) critical region on the X chromosome gene 1; NR0B1) cause X-linked AHC, a disease characterized by primary adrenal failure in infancy and hypogonadotropic hypogonadism. All known missense mutations impair DAX1 repression of steroidogenic factor 1 (SF1) transactivation and have been localized to the putative ligand binding domain. Here, an asymptomatic father and his late-onset AHC daughter were both shown to share a novel DAX1 mutation (C200W), the first missense mutation identified in the hinge region of DAX1. Using immunohistochemistry we demonstrate that the sub-cellular localization of the C200W mutant DAX1 protein is shifted from the nucleus to the cytoplasm. The disturbed localization of the C200W mutant in transfected cells correlates with impaired transcriptional repression activity. The import defect is relatively mild, retaining 80% of wild-type activity, which may explain the unusually mild phenotype. Import of DAX1 into the nucleus involves a direct interaction with SF1. In vitro assays demonstrate that the C200W mutant retains the ability to functionally interact with SF1, which suggests that SF1-independent interactions of DAX1 could be responsible for the import defect.
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Sex determination: A 'window' of DAX1 activity
Trends in endocrinology and metabolism: TEM, 2004Co-Authors: Louisa M Ludbrook, Vincent R HarleyAbstract:Traditionally, DAX1 was considered an 'anti-testis' gene because DAX1 duplications in XY individuals cause male-to-female sex reversal: dosage-sensitive sex reversal (DSS). In DSS, two active DAX1 genes on one X chromosome can abrogate testis formation. By contrast, mutations and deletions of DAX1 cause adrenal hypoplasia congenita (AHC). Although AHC patients develop testes, gonadal defects include disorganized testis cords and hypogonadotropic hypogonadism, which is not completely restored with gonadotropin or androgen therapy. Recent evidence of XY sex reversal in DAX1-deficient mice strongly supports a role for DAX1 as a 'pro-testis' gene. Therefore, perhaps DAX1/DAX1 acts within a 'window' of activity, outside of which testis formation does not occur. Here, we discuss the function and possible mechanisms of DAX1 action in male gonadogenesis.
Louisa M Ludbrook - One of the best experts on this subject based on the ideXlab platform.
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excess DAX1 leads to xy ovotesticular disorder of sex development dsd in mice by inhibiting steroidogenic factor 1 sf1 activation of the testis enhancer of sry box 9 sox9
Endocrinology, 2012Co-Authors: Louisa M Ludbrook, Janelle Ryan, Ryohei Sekido, Robin Lovellbadge, Dagmar Wilhelm, Stefan Bagherifam, Pascal Bernard, Vincent R HarleyAbstract:Human DAX1 duplications cause dosage-sensitive sex reversal (DSS) whereby chromosomally XY individuals can develop as females due to gonadal dysgenesis. However, the mechanism of DSS-adrenal hypoplasia congenita on X, gene 1 (DAX1) action in the fetal testis is unknown. We show that in fetal testes from XY DAX1-overexpressing transgenic mice, the expression of the key testis-promoting gene sex-determining region on Y (SRY)-box-9 (Sox9) is reduced. Moreover, in XY Sox9 heterozygotes, in which testis development is usually normal, DAX1 overexpression results in ovotestes, suggesting a DAX1-SOX9 antagonism. The ovarian portion of the XY ovotestes was characterized by expression of the granulosa cell marker, Forkhead box-L2, with complete loss of the Sertoli cell markers, SOX9 and anti-Mullerian hormone, and the Leydig cell marker CYP17A1. However, the expression of SRY and steroidogenic factor-1 (SF1), two key transcriptional regulators of Sox9, was retained in the ovarian portion of the XY ovotestes. Using ...
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excess DAX1 leads to xy ovotesticular disorder of sex development dsd in mice by inhibiting steroidogenic factor 1 sf1 activation of the testis enhancer of sry box 9 sox9
Endocrinology, 2012Co-Authors: Louisa M Ludbrook, Janelle Ryan, Ryohei Sekido, Robin Lovellbadge, Dagmar Wilhelm, Stefan Bagherifam, Pascal Bernard, Vincent R HarleyAbstract:Human DAX1 duplications cause dosage-sensitive sex reversal (DSS) whereby chromosomally XY individuals can develop as females due to gonadal dysgenesis. However, the mechanism of DSS-adrenal hypoplasia congenita on X, gene 1 (DAX1) action in the fetal testis is unknown. We show that in fetal testes from XY DAX1-overexpressing transgenic mice, the expression of the key testis-promoting gene sex-determining region on Y (SRY)-box-9 (Sox9) is reduced. Moreover, in XY Sox9 heterozygotes, in which testis development is usually normal, DAX1 overexpression results in ovotestes, suggesting a DAX1-SOX9 antagonism. The ovarian portion of the XY ovotestes was characterized by expression of the granulosa cell marker, Forkhead box-L2, with complete loss of the Sertoli cell markers, SOX9 and anti-Mullerian hormone, and the Leydig cell marker CYP17A1. However, the expression of SRY and steroidogenic factor-1 (SF1), two key transcriptional regulators of Sox9, was retained in the ovarian portion of the XY ovotestes. Using reporter mice, DAX1 overexpression reduced activation of TES, the testis enhancer of Sox9, indicating that DAX1 might repress Sox9 expression via TES. In cultured cells, increasing levels of DAX1 antagonized SF1-, SF1/SRY-, and SF1/SOX9-mediated activation of TES, due to reduced binding of SF1 to TES, providing a likely mechanism for DSS.
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177 a mechanism underlying disorders of sex development caused by DAX1 duplication
Reproduction Fertility and Development, 2009Co-Authors: Louisa M Ludbrook, Robin Lovellbadge, Vincent R Harley, R SekidoAbstract:The DAX1 protein is an orphan nuclear hormone receptor expressed in developing and adult hypothalamic, pituitary, adrenal and gonadal tissues. In humans, duplication of the DAX1 gene at locus Xp21 causes Disorders of Sex Development (DSD), whereby XY individuals develop as females, due to the failure of testicular development. DAX1 acts as a co-factor for nuclear receptor-mediated transcription of steroidogenic genes. In mice, overexpression of a DAX1 transgene causes delayed testis cord formation, a milder phenotype than that seen in human (1). Exactly how DAX1 duplication interferes with typical testicular development is unclear but a ‘window' of DAX1 activity was proposed (2). In order to identify the mechanism of DAX1 action when overexpressed in the developing XY gonad, we have used both in vivo and in vitro approaches. We hypothesised that, when present in excess, DAX1 must repress the action of early testis-forming genes. We investigated the effect of DAX1 over expression, using the DAX1 transgenic mouse line, DAX1812 (1), on expression of Sox9, a critical testis-forming gene. Immunostaining of DAX1812 gonads revealed reduced Sox9 expression, suggesting excess DAX1 antagonises Sox9 upregulation during the early stages of sex determination. To determine whether antagonism of Sox9 was occurring at the transcriptional level we assessed the effect of excess DAX1 on the activity of the Testis-Specific Enhancer of Sox9 (TES), which drives Sox9 transcription in the developing XY gonad (3). In combination, the in vivo and in vitro evidence strongly suggests that DAX1, when present in excess, can repress Sox9 expression through TES and that this repression occurs through inhibition of Steroidogenic Factor-1 activity. With this work we have identified a potential mechanism for disruption of the male-specific sex determination pathway caused by DAX1 duplication and leading to DSD in XY individuals.
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Sex determination: A 'window' of DAX1 activity
Trends in endocrinology and metabolism: TEM, 2004Co-Authors: Louisa M Ludbrook, Vincent R HarleyAbstract:Traditionally, DAX1 was considered an 'anti-testis' gene because DAX1 duplications in XY individuals cause male-to-female sex reversal: dosage-sensitive sex reversal (DSS). In DSS, two active DAX1 genes on one X chromosome can abrogate testis formation. By contrast, mutations and deletions of DAX1 cause adrenal hypoplasia congenita (AHC). Although AHC patients develop testes, gonadal defects include disorganized testis cords and hypogonadotropic hypogonadism, which is not completely restored with gonadotropin or androgen therapy. Recent evidence of XY sex reversal in DAX1-deficient mice strongly supports a role for DAX1 as a 'pro-testis' gene. Therefore, perhaps DAX1/DAX1 acts within a 'window' of activity, outside of which testis formation does not occur. Here, we discuss the function and possible mechanisms of DAX1 action in male gonadogenesis.
Larry J Jameson - One of the best experts on this subject based on the ideXlab platform.
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hypogonadotropic hypogonadism in subjects with DAX1 mutations
Molecular and Cellular Endocrinology, 2011Co-Authors: Unmesh Jadhav, Rebecca M Harris, Larry J JamesonAbstract:DAX1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1; also known as NROB1, nuclear receptor subfamily 0, group B, member 1) encodes a nuclear receptor that is expressed in embryonic stem (ES) cells, steroidogenic tissues (gonads, adrenals), the ventromedial hypothalamus (VMH), and pituitary gonadotropes. Humans with DAX1 mutations develop an X-linked syndrome referred to as adrenal hypoplasia congenita (AHC). These boys typically present in infancy with adrenal failure but later fail to undergo puberty because of hypogonadotropic hypogonadism (HHG). The adrenal failure reflects a developmental abnormality in the transition of the fetal to adult zone, resulting in glucocorticoid and mineralocorticoid deficiency. The etiology of HHG involves a combined and variable deficiency of hypothalamic GnRH secretion and/or pituitary responsiveness to GnRH resulting in low LH, FSH and testosterone. Treatment with exogenous gonadotropins generally does not induce spermatogenesis. Animal models indicate that DAX1 also plays a critical role in testis development and function. As a nuclear receptor, DAX1 has been shown to function as a transcriptional repressor, particularly of pathways regulated by other nuclear receptors, such as steroidogenic factor 1 (SF1). In addition to reproductive tissues, DAX1 is also expressed at high levels in ES cells and plays a role in the maintenance of pluripotentiality. Here we review the clinical manifestations associated with DAX1 mutations as well as the evolving information about its function based on animal models and in vitro studies.
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a phenotypic spectrum of sexual development in DAX1 nr0b1 deficient mice consequence of the c57bl 6j strain on sex determination
T200804847.pdf, 2008Co-Authors: Susan Y Park, Eun Jig Lee, Donna Emge, Carolyn L Jahn, Larry J JamesonAbstract:Nuclear receptor subfamily 0, group B, member 1 (Nr0b1; hereafter referred to as DAX1) is an orphan nuclear receptor that regulates adrenal and gonadal development. Dosage-sensitive sex reversal, adrenal hypoplasia congenita, critical region on the X chromosome, gene 1 (DAX1) mutations in the mouse are sensitive to genetic background. In this report, a spectrum of impaired gonadal differentiation was observed as a result of crossing the DAX1 knockout on the 129SvIm/J strain onto the C57BL/6J strain over two generations of breeding. DAX1-mutant XY mice of a mixed genetic background (129;B6DAX1−/Y [101 total]) developed gonads that were predominantly testislike (n = 61), ovarianlike (n = 27), or as intersex (n = 13). During embryonic development, Sox9 expression in the gonads of 129;B6DAX1−/Y mutants was distributed across a wide quantitative range, and a threshold level of Sox9 (>0.4-fold of wild-type) was associated with testis development. Germ cell fate also varied widely, with meiotic germ cells being more prevalent in the ovarianlike regions of embryonic gonads, but also observed within testicular tissue. Ptgds, a gene associated with Sox9 expression and Sertoli cell development, was markedly downregulated in DAX1−/Y mice. Stra8, a gene associated with germ cell meiosis, was upregulated in DAX1−/Y mice. In both cases, the changes in gene expression also occurred in pure 129 mice but were amplified in the B6 genetic background. Sertoli cell apoptosis was prevalent in 129;B6DAX1−/Y gonads. In summary, DAX1 deficiency on a partial B6 genetic background results in further modulation of gene expression changes that affect both Sertoli cell and germ cell fate, leading to a phenotypic spectrum of gonadal differentiation.
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nuclear receptors sf1 and DAX1 function cooperatively to mediate somatic cell differentiation during testis development
Development, 2005Co-Authors: Susan Y Park, Joshua J. Meeks, Jeffrey Weiss, Gary D. Hammer, Gerald Raverot, Liza E Pfaff, Larry J JamesonAbstract:Mutations of orphan nuclear receptors SF1 and DAX1 each cause adrenal insufficiency and gonadal dysgenesis in humans, although the pathological features are distinct. Because DAX1 antagonizes Sf1-mediated transcription in vitro, we hypothesized that DAX1 deficiency would compensate for allelic loss of Sf1. In studies of the developing testis, expression of the fetal Leydig cell markers Cyp17 and Cyp11a1 was reduced in heterozygous Sf1-deficient mice at E13.5, consistent with dose-dependent effects of Sf1. In Sf1/DAX1 (Sf1 heterozygous and DAX1-deleted) double mutant gonads, the expression of these genes was unexpectedly reduced further, indicating that loss of DAX1 did not compensate for reduced Sf1 activity. The Sertoli cell product Dhh was reduced in Sf1 heterozygotes at E11.5, and it was undetectable in Sf1/DAX1 double mutants, indicating that Sf1 and DAX1 function cooperatively to induce Dhh expression. Similarly, Amh expression was reduced in both Sf1 and DAX1 single mutants at E11.5, and it was not rescued by the Sf1/DAX1 double mutant. By contrast, Sox9 was expressed in single and in double mutants, suggesting that various Sertoli cell genes are differentially sensitive to Sf1 and DAX1 function. Reduced expression of Dhh and Amh was transient, and was largely restored by E12.5. Similarly, there was recovery of fetal Leydig cell markers by E14.5, indicating that loss of Sf1/DAX1 delays but does not preclude fetal Leydig cell development. Thus, although Sf1 and DAX1 function as transcriptional antagonists for many target genes in vitro, they act independently or cooperatively in vivo during male gonadal development.
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leydig cell specific expression of DAX1 improves fertility of the DAX1 deficient mouse
Biology of Reproduction, 2003Co-Authors: Joshua J. Meeks, Theron A. Russell, Jeffrey Weiss, Baxter Jeffs, Ilpo Huhtaniemi, Larry J JamesonAbstract:Abstract DAX1 is an orphan nuclear receptor expressed in both Leydig and Sertoli cells of the testis. Mutation of DAX1 in humans causes adrenal failure and hypogonadotropic hypogonadism. Targeted mutagenesis of DAX1 in mice reveals a primary gonadal defect characterized by overexpression of aromatase and cellular obstruction of the seminiferous tubules and efferent ductules, leading to germ cell death and infertility. Transgenic expression of DAX1 under the control of the mullerian-inhibiting substance promoter, which is selectively expressed in Sertoli cells, improves fertility but does not fully correct the histological abnormalities in the testes of DAX1 knockout (DAX1KO) mice. We therefore hypothesized that DAX1 may also play a crucial role in other somatic cells of the testis, namely the Leydig cells. A 2.1-kilobase fragment of the murine LH receptor 5′-promoter (LHR-DAX1) was used to generate transgenic mice that selectively express DAX1 in Leydig cells. Expression of the LHR-DAX1 transgene caused n...
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an alternate translation initiation site circumvents an amino terminal DAX1 nonsense mutation leading to a mild form of x linked adrenal hypoplasia congenita
The Journal of Clinical Endocrinology and Metabolism, 2003Co-Authors: Gokhan Ozisik, Jeffrey Weiss, Giovanna Mantovani, Anna Spada, Paolo Beckpeccoz, Luca Persani, John C Achermann, Larry J JamesonAbstract:Mutations in DAX1 [dosage-sensitive sex reversal-adrenal hypoplasia congenita (AHC) critical region on the X chromosome gene 1; NR0B1] cause X-linked AHC, a disease characterized by primary adrenal failure in infancy or childhood and reproductive abnormalities later in life. Most of these patients have nonsense or frameshift mutations that cause premature truncation of the DAX1 protein, thereby eliminating its transcriptional silencing activity. We evaluated a patient with an unusual form of AHC manifest as late-onset adrenal insufficiency and gonadal failure. DNA sequence analysis revealed a novel amino-terminal DAX1 nonsense mutation (Q37X), predicted to cause a severe truncation of the protein. Using a combination of in vitro translation assays and studies of DAX1 expression and function in transfected cells, we demonstrate that, in contrast to more distal mutations leading to a nonfunctional protein, this mutation is associated with a milder phenotype due to the expression of a partially functional, a...
Gary D. Hammer - One of the best experts on this subject based on the ideXlab platform.
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Timing of adrenal regression controlled by synergistic interaction between Sf1 SUMOylation and DAX1.
Development (Cambridge England), 2017Co-Authors: Yewei Xing, Ken Ichirou Morohashi, Holly A. Ingraham, Gary D. HammerAbstract:The nuclear receptor steroidogenic factor 1 (Sf1, Nr5a1, Ad4bp) is crucial for formation, development and function of steroidogenic tissues. A fetal adrenal enhancer (FAdE) in the Sf1 gene was previously identified to direct Sf1 expression exclusively in the fetal adrenal cortex and is bound by both Sf1 and DAX1. Here, we have examined the function of Sf1 SUMOylation and its interaction with DAX1 on FAdE function. A diffused prolonged pattern of FAdE expression and delayed regression of the postnatal fetal cortex (X-zone) were detected in both the SUMOylation-deficient-Sf12KR/2KR and DAX1 knockout mouse lines, with FAdE expression/activity retained in the postnatal 20αHSD-positive postnatal X-zone cells. In vitro studies indicated that Sf1 SUMOylation, although not directly influencing DNA binding, actually increased binding of DAX1 to Sf1 to further enhance transcriptional repression of FAdE. Taken together, these studies define a crucial repressor function of Sf1 SUMOylation and DAX1 in the physiological cessation of FAdE-mediated Sf1 expression and the resultant regression of the postnatal fetal cortex (X-zone).
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evidence of adrenal failure in aging DAX1 deficient mice
Endocrinology, 2011Co-Authors: Joshua O Scheys, Joanne H Heaton, Gary D. HammerAbstract:Dosage-sensitive sex reversal, adrenal hypoplasia congenita (AHC) critical region on the X chromosome, gene 1 (DAX1) is an orphan nuclear receptor essential for development and function of the mammalian adrenal cortex and gonads. DAX1 was cloned as the gene responsible for X-linked AHC, which is characterized by adrenocortical failure necessitating glucocorticoid replacement. Contrary to these human data, young mice with genetic DAX1 knockout (DAX1(-/Y)) exhibit adrenocortical hyperfunction, consistent with the historic description of DAX1 as a transcriptional repressor that inhibits steroidogenic factor 1-dependent steroidogenesis. This paradox of molecular function and two apparently opposite phenotypes associated with DAX1 deficiency in mice and humans is compounded by the recent observations that under certain circumstances, DAX1 can serve as a transcriptional activator of steroidogenic factor 1. The recently revealed role of DAX1 in embryonic stem cell pluripotency, together with the observation that its expression in the adult adrenal is restricted to the subcapsular cortex, where presumptive undifferentiated progenitor cells reside, has led us to reexamine the phenotype of DAX1(-/Y) mice in order to reconcile the conflicting mouse and human data. In this report, we demonstrate that although young DAX1(-/Y) mice have enhanced steroidogenesis and subcapsular adrenocortical proliferation, as these mice age, they exhibit declining adrenal growth, decreasing adrenal steroidogenic capacity, and a reversal of their initial enhanced hormonal sensitivity. Together with a marked adrenal dysplasia in aging mice, these data reveal that both DAX1(-/Y) mice and patients with X-linked AHC exhibit adrenal failure that is consistent with adrenocortical subcapsular progenitor cell depletion and argue for a significant role of DAX1 in maintenance of these cells.
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lrh 1 and nanog regulate DAX1 transcription in mouse embryonic stem cells
Molecular and Cellular Endocrinology, 2011Co-Authors: Victoria R Kelly, Gary D. HammerAbstract:Abstract DAX1, an atypical orphan nuclear receptor expressed in steroidogenic tissues, has recently been shown to be expressed in mouse embryonic stem (mES) cells and is required for pluripotency. While the mechanisms of transcriptional regulation of DAX1 in steroidogenic organs have been well characterized, those in mES cells have not. Here we report that 500 bp of the DAX1 gene promoter sequence are sufficient to drive expression in mES cells. In steroidogenic tissues, NR5A1 (Sf1) binds to nuclear receptor binding sites within this sequence to regulate DAX1 expression. In mES cells, while NR5A1 (Sf1) is not expressed, NR5A2 (LRH-1) expression is robust. Luciferase assays, EMSA and overexpression/knockdown studies demonstrate that LRH-1 binds the −128 site and regulates DAX1 in mES cells. Predicated on recent work indicating that Nanog binds to the DAX1 intron, we have used chromatin immunoprecipitation experiments (ChIP) to define an intronic site that is bound by Nanog. Overexpression and knockdown of Nanog in mES cells result in alteration of DAX1 expression, and luciferase assays reveal that this sequence can enhance transcription of a DAX1 reporter construct. These data indicate that LRH-1 and Nanog cooperate to regulate DAX1 expression in mES cells.
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DAX1 up regulates oct4 expression in mouse embryonic stem cells via lrh 1 and sra
Molecular Endocrinology, 2010Co-Authors: Victoria R Kelly, Rork Kuick, Ronald J Koenig, Gary D. HammerAbstract:DAX1 (Nr0b1) is an atypical orphan nuclear receptor that has recently been shown to play a role in mouse embryonic stem (mES) cell pluripotency. Here we describe a mechanism by which DAX1 maintains pluripotency. In steroidogenic cells, DAX1 protein interacts with the NR5A nuclear receptor steroidogenic factor 1 (Nr5a1) to inhibit transcription of target genes. In mES cells, liver receptor homolog 1 (LRH-1, Nr5a2), the other NR5A family member, is expressed, and LRH-1 has been shown to interact with DAX1. We demonstrate by coimmunoprecipitation that DAX1 is, indeed, able to form a complex with LRH-1 in mES cells. Because DAX1 was historically characterized as an inhibitor of steroidogenic factor 1-mediated transcriptional activation, we hypothesized that DAX1 would inhibit LRH-1 action in mES cells. Therefore, we examined the effect of DAX1 on the LRH-1-mediated activation of the critical ES cell factor Oct4 (Pou5f1). Chromatin immunoprecipitation localized DAX1 to the Oct4 promoter at the LRH-1 binding site, and luciferase assays together with DAX1 overexpression and knockdown experiments revealed that, rather than repress, DAX1 accentuated LRH-1-mediated activation of the Oct4 gene. Similar to our previously published studies that defined the RNA coactivator steroid receptor RNA activator as the critical mediator of DAX1 coactivation function, DAX1 augmentation of LRH-1-mediated Oct4 activation is dependent upon steroid receptor RNA activator. Finally, utilizing published chromatin immunoprecipitation data of whole-genome binding sites of LRH-1 and DAX1, we show that LRH-1 and DAX1 commonly colocalize at 288 genes (43% of LRH-1 target genes), many of which are involved in mES cell pluripotency. Thus, our results indicate that DAX1 plays an important role in the maintenance of pluripotency in mES cells through interaction with LRH-1 and transcriptional activation of Oct4 and other genes.
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nuclear receptors sf1 and DAX1 function cooperatively to mediate somatic cell differentiation during testis development
Development, 2005Co-Authors: Susan Y Park, Joshua J. Meeks, Jeffrey Weiss, Gary D. Hammer, Gerald Raverot, Liza E Pfaff, Larry J JamesonAbstract:Mutations of orphan nuclear receptors SF1 and DAX1 each cause adrenal insufficiency and gonadal dysgenesis in humans, although the pathological features are distinct. Because DAX1 antagonizes Sf1-mediated transcription in vitro, we hypothesized that DAX1 deficiency would compensate for allelic loss of Sf1. In studies of the developing testis, expression of the fetal Leydig cell markers Cyp17 and Cyp11a1 was reduced in heterozygous Sf1-deficient mice at E13.5, consistent with dose-dependent effects of Sf1. In Sf1/DAX1 (Sf1 heterozygous and DAX1-deleted) double mutant gonads, the expression of these genes was unexpectedly reduced further, indicating that loss of DAX1 did not compensate for reduced Sf1 activity. The Sertoli cell product Dhh was reduced in Sf1 heterozygotes at E11.5, and it was undetectable in Sf1/DAX1 double mutants, indicating that Sf1 and DAX1 function cooperatively to induce Dhh expression. Similarly, Amh expression was reduced in both Sf1 and DAX1 single mutants at E11.5, and it was not rescued by the Sf1/DAX1 double mutant. By contrast, Sox9 was expressed in single and in double mutants, suggesting that various Sertoli cell genes are differentially sensitive to Sf1 and DAX1 function. Reduced expression of Dhh and Amh was transient, and was largely restored by E12.5. Similarly, there was recovery of fetal Leydig cell markers by E14.5, indicating that loss of Sf1/DAX1 delays but does not preclude fetal Leydig cell development. Thus, although Sf1 and DAX1 function as transcriptional antagonists for many target genes in vitro, they act independently or cooperatively in vivo during male gonadal development.
