Steroidogenic factor (SF1) is an orphan nuclear receptor that is essential for steroid hormone-biosynthesis and endocrine development. Recent studies have demonstrated that phospholipids are ligands for SF1. In the present study our aim was to identify endogenous ligands for SF1 and characterize their functional significance in mediating cAMP-dependent transcription of human CYP17. Using mass spectrometry we show that in H295R adrenocortical cells SF1 is bound to sphingosine (SPH) under basal conditions and that cAMP stimulation decreases the amount of SPH bound to the receptor. We also show that silencing both acid and neutral ceramidases using siRNA induces CYP17 mRNA expression, suggesting that SPH acts as an inhibitory ligand. In vitro analysis of ligand binding using scintillation proximity assays show that several sphingolipids and phospholipids, including phosphatidic acid (PA), can compete with [3H]SPH for binding to SF1, suggesting that SF1 may have more than one ligand and binding specificity may change with the changes in intracellular fluxes of phospholipids. Further, phosphatidic acid (PA) induces SF1-dependent transcription of CYP17 reporter constructs. Inhibition of diacyglycerol kinase (DAGK) activity using R59949 and silencing DAGK- expression attenuates SF1-dependent CYP17 transcriptional. We propose that PA is an activating ligand for SF1 and that cAMP-stimulated activation of SF1 takes place by displacement of SPH.

Adenylyl cyclase (Adcy) is an important early effector of adrenocorticotrophin (ACTH) on the adrenal cortex; however, this enzyme consists of ten isozymes in mammalian cells and the factors governing the expression of different Adcy isozymes have not been well defined. The aim of this study is to investigate the regulation of mouse Adcy4, one of ten isozymes, in Y1 adrenocortical tumor cells and in mutant subclones derived from the Y1 cells. Adcy4 is expressed at a high level in brain but at lower levels in many other tissues including the Y1 cells. Moreover, this isozyme is specifically deficient in Y1 mutants with impaired steroidogenic factor 1 (SF1) activity. These observations support a hypothesis that Adcy4 expression is influenced by both ubiquitously expressed and tissue-specific transcription factors. My sequencing results indicate that mouse Adcy4 is highly homologous to the human and rat counterparts; its gene is located less than 1 kb downstream of Ripk3 and contains 26 exons. Primer extension and in silico analyses suggest that Adcy4 contains a TATA-less promoter and initiates transcription from multiple sites. Luciferase reporter gene assays indicate that Adcy4 promoter activity is mainly stimulated by the proximal GC-rich region but is inhibited by the first intron. This 124 bp GC-rich region is well conserved among several mammalian species and exhibits strong promoter activity in Y1 cells, which is functionally compromised in the Adcy4-deficient mutant. Within this region, three Sp1/Sp3- and one SF1-binding sites have been identified which bind the corresponding proteins Sp1 and Sp3 or SF1 in electrophoretic mobility shift assays (EMSAs). Site-directed mutagenesis reveals that the 5’-most Sp1/Sp3 site enhances Adcy4 promoter activity, whereas the middle Sp1/Sp3 and SF1 sites each repress this activity. In Y1 mutant cells, mutating the SF1 site restores Adcy4 promoter activity and knocking down SF1 with shRNA increases Adcy4 expression. All these data demonstrate that Adcy4 expression is under the control of the ubiquitous factors Sp1 and Sp3 and the tissue-specific factor SF1 and establish that SF1 is a repressor for Adcy4 promoter activity. This study is the first to demonstrate a repressor function for SF1 in certain promoter contexts.

Adenylyl cyclase (Adcy) is an important early effector of adrenocorticotrophin (ACTH) on the adrenal cortex; however, this enzyme consists of ten isozymes in mammalian cells and the factors governing the expression of different Adcy isozymes have not been well defined. The aim of this study is to investigate the regulation of mouse Adcy4, one of ten isozymes, in Y1 adrenocortical tumor cells and in mutant subclones derived from the Y1 cells. Adcy4 is expressed at a high level in brain but at lower levels in many other tissues including the Y1 cells. Moreover, this isozyme is specifically deficient in Y1 mutants with impaired steroidogenic factor 1 (SF1) activity. These observations support a hypothesis that Adcy4 expression is influenced by both ubiquitously expressed and tissue-specific transcription factors. My sequencing results indicate that mouse Adcy4 is highly homologous to the human and rat counterparts; its gene is located less than 1 kb downstream of Ripk3 and contains 26 exons. Primer extension and in silico analyses suggest that Adcy4 contains a TATA-less promoter and initiates transcription from multiple sites. Luciferase reporter gene assays indicate that Adcy4 promoter activity is mainly stimulated by the proximal GC-rich region but is inhibited by the first intron. This 124 bp GC-rich region is well conserved among several mammalian species and exhibits strong promoter activity in Y1 cells, which is functionally compromised in the Adcy4-deficient mutant. Within this region, three Sp1/Sp3- and one SF1-binding sites have been identified which bind the corresponding proteins Sp1 and Sp3 or SF1 in electrophoretic mobility shift assays (EMSAs). Site-directed mutagenesis reveals that the 5’-most Sp1/Sp3 site enhances Adcy4 promoter activity, whereas the middle Sp1/Sp3 and SF1 sites each repress this activity. In Y1 mutant cells, mutating the SF1 site restores Adcy4 promoter activity and knocking down SF1 with shRNA increases Adcy4 expression. All these data demonstrate that Adcy4 expression is under the control of the ubiquitous factors Sp1 and Sp3 and the tissue-specific factor SF1 and establish that SF1 is a repressor for Adcy4 promoter activity. This study is the first to demonstrate a repressor function for SF1 in certain promoter contexts.

Orientador: Marcilda Palandi de Mello / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-22T17:47:27Z (GMT). No. of bitstreams: 1 Fabbri_HelenaCampos_M.pdf: 5693726 bytes, checksum: f3da0b3f4f94d25ac46393e9f831a748 (MD5) Previous issue date: 2013 / Resumo: O termo Distúrbio da Diferenciação do Sexo (DDS) caracteriza-se pelo desenvolvimento genital ou gonadal incompleto ou desordenado. Os DDS com cariótipo 46,XY são caracterizados por genitália externa ambígua ou feminina, em alguns casos com gônadas disgenéticas, e presença ou ausência de derivados de Müller. Os mais frequentes são a insensibilidade androgênica, deficiência da 5-alfa-redutase tipo 2, disgenesia gonadal e DDS ovário-testicular. Vários são os genes que participam dos processos de determinação e diferenciação do sexo. Alterações no gene NR5A1, que codifica o fator de transcrição SF- 1, é responsável por diferentes fenótipos de DDS. A proteína SF-1 é expressa principalmente em tecidos esteroidogênicos (gônadas, adrenais e placenta), nas células de Sertoli, nas células de Leydig e nos ovários; é o principal regulador do metabolismo do colesterol nas células esteroidogênicas. Além disso, regula a atividade de outros genes, como os CYPs, HSD3B, StAR, SOX9, DAX1, entre outros. Na literatura são descritas alterações no gene NR5A1 associadas à DDS 46,XY, anorquia bilateral, amenorréia primária, falência ovariana precoce, hipospádia, infertilidade masculina, e alguns casos de tumores adrenais e endometrioses. Neste trabalho foi realizada a análise molecular do gene NR5A1 em 86 pacientes com DDS 46,XY, incluindo-se disgenesia gonadal completa (n = 7), disgenesia gonadal parcial (n = 18), DDS 46,XY idiopático (n = 41) e outros (n = 20). Doze alterações foram identificadas neste trabalho, sendo: sete na região codificante (p.Ser32Asn, p.Arg39Cis, p.Lis38*, p.Cis65Tir, p.L80Wfs*8, p.Cis247*, and p.Asp364Trefs*18), uma em sítio de splicing (c.1138+1G>T), duas no exon 1 nãocodificante (c.-133G>A e c.-156_-136ins18pb), três na região 5'UTR (c.-413G>A, c.- 208C>A, e c.-762C>T) e uma na região 3'UTR (c.*1286C>T). As variações aqui descritas, não foram identificadas em controles saudáveis. As análises in silico demonstraram o possível efeito deletério de cada alteração e, suas relações com o fenótipo dos indivíduos. Embora estes resultados demonstrem a importância de cada alteração para o fenótipo, haverá ainda a necessidade de se investigar os efeitos funcionais in vitro. As alterações com potencial deletério foram identificadas em maior frequência nos casos dos distúrbios da diferenciação gonadal (20%) e DDS 46,XY idiopático (22%) / Abstract: The term Disorders of Sex Differentiation (DSD) characterize incomplete or disorganized genital or gonadal development. The DSD with 46, XY karyotype may present either ambiguous or female genitalia and also dysgenetic gonads in some cases, with presence or absence of Müllerian derivatives. The most frequent are androgen insensitivity, 5-alpha-reductase type 2 deficiency, gonadal dysgenesis and ovarian-testicular DSD. There are several genes that participate in both sex determination and differentiation processes. Mutations in NR5A1 gene, which encoding SF-1, a transcription factor, are responsible for different phenotypes of DSD. The protein SF-1, which is expressed mainly in steroidogenic tissues (gonads, adrenal glands and placenta), is also express in Sertoli and Leydig cells, in the ovaries, and is the major regulator of cholesterol metabolism in steroidogenic cells. Moreover, it regulates the activity of other genes, such as CYPs, HSD3B, StAR, SOX9, DAX1, among others. The literature describes the association of changes in NR5A1 gene with 46, XY DSD, bilateral anorchia, primary amenorrhea, premature ovarian failure, hypospadias, male infertility, and some cases of adrenal tumors and endometriosis. The present work involved the molecular analysis of NR5A1 gene in 86 patients with 46, XY DSD including complete gonadal dysgenesis (n = 7), partial gonadal dysgenesis (n = 18), idiopathic 46, XY DSD (n = 41) and others (n = 20). Twelve variations had been identified: seven in the coding region (p.Ser32Asn, p.Arg39Cis, p.Lis38*, p.Cis65Tir, p.L80Wfs*8, p.Cis247*, and p.Asp364Trefs*18), one at a splice site (c.1138+1 G>T), two in the noncoding exon 1 (c.-133G>A and c.-156_-136ins18pb), three in the 5'UTR region (c.- 413G>A, c.-208C>A and c.-762C>T) and one in the 3'UTR (c.*1286C>T). The variations herein described, have not been identified in healthy controls. In silico analysis showed possible deleterious effects for each change and its correlations to individual phenotypes. Although those results demonstrate the importance of each change for the phenotype, there in vitro functional effects must be investigated. The potentially deleterious changes were identified more frequently in cases of disorders of gonadal development (20%) and idiopathic 46, XY DSD (22%) / Mestrado / Genetica Animal e Evolução / Mestra em Genética e Biologia Molecular

Sphingolipids modulate multiple cellular functions, including steroid hormone biosynthesis. Sphingosine is an antagonist ligand for the nuclear receptor steroidogenic factor 1 (SF-1), which is the primary transcriptional regulator of most steroidogenic genes. Furthermore, sphingosine-dependent repression of SF-1 function is dependent on the expression of acid ceramidase (ASAH1), an enzyme that forms sphingosine. Based on these data, I hypothesized that ACTH/cAMP signaling regulates ASAH1 function at both transcriptional and post-transcriptional levels. In addition, because SF-1 is predominantly a nuclear protein, I postulated that ASAH1 modulates SF-1 function and, therefore, steroidogenic gene expression by controlling the nuclear concentrations of SPH. To test these hypotheses, I first examined the effect of chronic ACTH/cAMP signaling on the transcription of the ASAH1 gene. Next, the functional significance of ASAH1 expression in adrenocortical cells was probed by generating an ASAH1-knockdown cell line. I subsequently characterized the role of ASAH1 as a transcriptional nuclear receptor coregulator. Finally, I defined the role of sphingosine-1-phosphate, a bi-product of ASAH1 activity, in the acute phase of cortisol biosynthesis. Using a variety of experimental approaches, I identified cAMP response element binding protein as an essential transcriptional activator of the ASAH1 gene. Analysis of adrenocortical cells lacking ASAH1 revealed that ASAH1 is a global regulator of steroidogenic capacity. Furthermore, I identified ASAH1 as a nuclear protein and defined the molecular determinants of the interaction between ASAH1 and SF-1. Collectively, this body of work establishes the integral role of ASAH1 in the regulation of ACTH-dependent adrenocortical cortisol biosynthesis.

Cortisol and dehydroepiandrosterone (DHEA) are steroids produced by the zona fasciculata (ZF) and reticularis (ZR), respectively, of the adrenal cortex. Both steroids are upregulated in response to adrenocorticotropic hormone (ACTH). Cortisol is a glucorticoid that is important in the regulation of inflammation and metabolism. DHEA is an adrenal androgen important in fetal growth and puberty but tends to decrease gradually after puberty in both men and women. DHEA has various effects on metabolism and immune function including inhibiting the effects of cortisol on some tissues. During the acute phase of stress, cortisol and DHEA rise due to an increase in ACTH released from the anterior pituitary. In contrast, during chronic stress, cortisol remains elevated but DHEA and ACTH levels decrease. Likewise, stress causes serum levels of IL-6 to increase. IL-6 increases cortisol release from the human and bovine adrenal cortex. IL-6 also decreases DHEA release from zona reticularis of the bovine adrenal gland. In humans the effect of IL-6 on DHEA production is still uncertain. To determine a possible mechanism of IL-6 on the zona fasciculata and reticularis, human H294R cells and bovine adrenal tissue were incubated in serum free medium containing IL-6, at various concentrations and incubation intervals. At the end of the incubation interval, mRNA or protein was extracted from the cells or tissue. Standard PCR, real time PCR, and western blot assays were used to determine the effects of IL-6 on the enzymes involved in cortisol and DHEA synthesis, steroidogenic factor-1 (SF-1), steroidogenic acute regulatory protein (StAR), and dosage sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome, gene 1 (DAX-1). In human H295R cells and bovine zona fasciculata cells IL-6 caused an increase in SF-1, StAR, P450scc, 17α hydroxylase, 3β-hydroxysteroid dehydrogenase type 2 (3β HSD2), 21 hydroxylase, and 11β hydroxylase mRNA and protein. IL-6 caused DAX-1 mRNA and protein to decrease. These effects were manifest in a time dependent manner. Dose response treatments incubated for 60 min increased SF-1, StAR, P450scc, 17α hydroxylase, 3β HSD2, 21 hydroxylase, and 11β hydroxylase but there was not significant change between the different treatments of IL-6. The bovine zona reticularis stimulated with IL-6 showed a decrease in SF-1, StAR, P450scc, 17α hydroxylase, and 3β HSD2 with an increase in DAX-1 mRNA and protein. This response was manifest in a time dependent manner for both mRNA and protein, and the effect was dose-dependent for mRNA but not protein levels within the 60 min time period. These data provide a mechanism by which increased stress, physical or emotional, which increases IL-6 serum level, could increase cortisol and decrease DHEA. This would account for decreased immune function, increased blood pressure, and changes in metabolism.

O Pseudohermafroditismo masculino disgenético (Anomalia da diferenciação sexual 46,XY ADS 46,XY) é definido como ambigüidade genital num paciente com testículos e/ou cariótipo 46,XY com uma das seguintes características: alteração histológica testicular, ausência ou hipoplasia das células de Leydig em tecido previamente estimulado com gonadotrofina coriônica humana(hCG), falta de resposta de testosterona ao estímulo com hCG sem acúmulo de precursores, ausência de células germinativas, presença de derivados müllerianos indicando inadequada produção do hormônio antiMülleriano (HAM) ou resistência de seus receptores. Esse estudo apresenta uma avaliação clínica, laboratorial, anátomopatológica, morfométrica e molecular de 10 pacientes com ADS 46,XY; dois pacientes apresentaram mutação no SF1 (fator esteroidogênico 1), duas mutações no domínio hingee uma terceira produziu um stop códon na posição 404; três pacientes com deleção da cópia do DAZ2. A morfometria testicular mostrou todos os diâmetros tubulares médios (DTM) moderado a gravemente diminuídos e os índices de fertilidade tubular leve a moderadamente diminuídos. Devido à dificuldade do diagnóstico diferencial e etiológico, o estudo morfométrico e molecular deve sempre acompanhar esses casos de ADS 46,XY. / The dysgenetic male pseudohermaphroditism 46,XY ; disorders of sex development (DSD 46,XY) is defined as sexual ambiguity in patients with testis and/or 46,XY karyotype and one of the characteristics: hystologic alteration of the testis; absence or hypoplasia of Leydig cells; a decreased testosterone response to human chorionic gonadotropin stimulation without accumulation of testosterone precursors; absent germ cells; presence of müllerian duct derivatives showing inappropriate production of antimüllerian hormone (AMH) or resistance to its receptors. This study shows the clinic, laboratory, histologic, morphometric and molecular evaluation of 10 patients with DSD 46,XY; two patients showed mutations in the SF1 gene (steroidogenic factor-1); two in the hinge domain and one stop codon at the position 404 of the protein; three patients exhibited deletion of DAZ2. The testis morphometry showed reduction: marked to severe of all mean tubular diameter (MTD) while the reduction of the tubular fertility index (TFI) were slight to marked. Due to difficulties establishing the differential diagnosis and the etiology, the morphometric and molecular evaluation must be always done in the patients with DSD 46,XY.

O Pseudohermafroditismo masculino disgenético (Anomalia da diferenciação sexual 46,XY ADS 46,XY) é definido como ambigüidade genital num paciente com testículos e/ou cariótipo 46,XY com uma das seguintes características: alteração histológica testicular, ausência ou hipoplasia das células de Leydig em tecido previamente estimulado com gonadotrofina coriônica humana(hCG), falta de resposta de testosterona ao estímulo com hCG sem acúmulo de precursores, ausência de células germinativas, presença de derivados müllerianos indicando inadequada produção do hormônio antiMülleriano (HAM) ou resistência de seus receptores. Esse estudo apresenta uma avaliação clínica, laboratorial, anátomopatológica, morfométrica e molecular de 10 pacientes com ADS 46,XY; dois pacientes apresentaram mutação no SF1 (fator esteroidogênico 1), duas mutações no domínio hingee uma terceira produziu um stop códon na posição 404; três pacientes com deleção da cópia do DAZ2. A morfometria testicular mostrou todos os diâmetros tubulares médios (DTM) moderado a gravemente diminuídos e os índices de fertilidade tubular leve a moderadamente diminuídos. Devido à dificuldade do diagnóstico diferencial e etiológico, o estudo morfométrico e molecular deve sempre acompanhar esses casos de ADS 46,XY. / The dysgenetic male pseudohermaphroditism 46,XY ; disorders of sex development (DSD 46,XY) is defined as sexual ambiguity in patients with testis and/or 46,XY karyotype and one of the characteristics: hystologic alteration of the testis; absence or hypoplasia of Leydig cells; a decreased testosterone response to human chorionic gonadotropin stimulation without accumulation of testosterone precursors; absent germ cells; presence of müllerian duct derivatives showing inappropriate production of antimüllerian hormone (AMH) or resistance to its receptors. This study shows the clinic, laboratory, histologic, morphometric and molecular evaluation of 10 patients with DSD 46,XY; two patients showed mutations in the SF1 gene (steroidogenic factor-1); two in the hinge domain and one stop codon at the position 404 of the protein; three patients exhibited deletion of DAZ2. The testis morphometry showed reduction: marked to severe of all mean tubular diameter (MTD) while the reduction of the tubular fertility index (TFI) were slight to marked. Due to difficulties establishing the differential diagnosis and the etiology, the morphometric and molecular evaluation must be always done in the patients with DSD 46,XY.