Made available in DSpace on 2014-06-11T19:25:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-11-17Bitstream added on 2014-06-13T18:53:44Z : No. of bitstreams: 1 cruz_jb_me_botfm.pdf: 449482 bytes, checksum: 5627323423c217568fc73820cbf66a6a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A hipófise anterior compõe-se de cinco tipos celulares que são definidos pelos hormônios que secretam. A diferenciação desses tipos celulares resulta de uma cascata temporalmente regulada de fatores transcricionais expressos no tecido hipofisário. Mutações de um desses fatores podem resultar tanto em defeitos estruturais da glândula como em deficiências hormonais, que podem ser isoladas (Déficit de hormônio do crescimento - DGH) ou combinadas (DHHC), dependendo do papel do fator transcricional mutado. A Displasia Septo – óptica (DSO) caracteriza-se pela presença de hipoplasia hipofisária, hipoplasia de nervo óptico e/ou má formações de estruturas da linha média. Foram avaliados 11 pacientes com quadro clinico de SOD, DGH e DHHC e realizado o sequenciamento genético do gene HESX1 desses indivíduos. Nos casos de DHHC foi feita uma análise adicional do gene PROP1. A mutação missense em estado de heterozigose A1772G levando a substituição N125S foi identificada em um paciente portador de DSO, no gene HESX1. Essa troca já foi previamente relatada como um polimorfismo na população Afro-Caribenha. Encontramos três pacientes portadores da variante alélica A9A e N20S no exon 1 do gene PROP1, já descritos previamente na literatura como polimorfismos. / The anterior pituitary is made of five types of cell defined according to the hormones they secrete. Differentiation among such cell types derives from a cascade of temporally regulated transcriptional factors expressed in the pituitary tissue. Mutation in one of these factors may result in both structural gland defects and hormonal deficiencies, which may be either isolated (DGH – Growth Hormone Deficiency) or combined, depending on the role of the mutated transcriptional factor. Septo-optic dysplasia (SOD) is characterized by pituitary hypoplasia, optic nerve hypoplasia and/or malformation of medium line structures. Eleven patients with a clinical state of SOD, DGH and CPHD were assessed, and genetically sequenced for the HESX1 gene. For CPHD cases, an additional analysis for the PROP1 gene was also conducted. One SOD patient was found to have a missense mutation in A1772G heterozygosis state, leading to the N125S replacement, in HESX1 gene. Such replacement has already been reported as a polymorphism in the Afro-Caribbean population. We found three patients with the alelic variation A9S and N20A in exon 1 of PROP1 gene, previously described as polymorphisms.

Le récepteur hypophysaire de la GnRH (RGnRH) joue un rôle crucial dans le contrôle de la fonctionde reproduction. Dans le promoteur distal du Rgnrh, j'ai caractérisé un élément de réponsebifonctionnel répondant aux protéines LIM à homéodomaine ISL1/LHX3 et à GATA2. D'autre part,deux motifs TAAT situés dans la région plus proximale confèrent à ce gène la capacité de répondreaux facteurs Paired-like PROP1 et OTX2. Tous ces facteurs, exprimés précocement au cours del'ontogenèse hypophysaire, pourraient participer à l'émergence de l'expression du Rgnrh. Hors del'hypophyse, j'ai découvert que le Rgnrh est exprimé au cours du développement postnatal dansl'hippocampe de rat, où il module la plasticité synaptique. Par ailleurs, j'ai identifié deux nouveauxsites d'expression, la rétine et la glande pinéale. Ces résultats mettent en lumière l'importancefonctionnelle de ce récepteur et de son ligand et les rôles multiples qu'il ont acquis au cours del'évolution des Vertébrés.

L’hypopituitarisme se définit par le déficit d’une ou plusieurs hormones hypophysaires.L’hypopituitarisme congénital est lié à des mutations de facteurs de transcriptionimpliqués dans le développement hypophysaire. Identifier les mécanismes et étiologiesd’hypopituitarisme congénital doit permettre d’améliorer les traitements des patients.Dans cette optique, ce travail a porté sur 3 aspects :Clarifier les mécanismes permettant la différenciation des lignées hypophysaires. Aucours du développement hypophysaire chez la souris, il existe un phénomène complexed’interaction entre 2 facteurs de transcription à homéodomaine paired (Prop1 et Hesx1),la voie Wnt-ßcaténine et les co-répresseurs de la famille Groucho/TLE. Ces interactionssont nécessaires à l’expression d’un autre facteur de transcription hypophysaire, Pit-1(Pou1f1), impliqué dans la différentiation des lignées hypophysaires somato-lactotropeset thyréotropes. Nous avons démontré in vitro, que les co-répresseurs de la famille TLEjouaient un rôle inhibiteur direct sur l’activation de l’early enhancer de POU1F1 à e12-e13, indépendamment de l’action de HESX1. Nos modèles de souris transgéniquesavec expression permanente de HESX1 et TLE3 permettent de mettre en évidence lerôle inhibiteur majeur de HESX1, et le rôle accessoire de TLE3. Les mutations dePROP1 étant à l’origine d’une expression persistante de HESX1 et TLE3, il est probablequ’ils jouent un rôle dans le déficit en sous-unité alpha observé chez les patientsdéficitaires en PROP1.Identifier et analyser la signification fonctionnelle de nouveaux variants alléliques dugène d’un facteur de transcription à homéodomaine LIM, LHX4. La mutation T99fs deLHX4 est à l’origine d’un phénotype hypophysaire très variable au sein d’une mêmefamille, en termes de déficits et de morphologie hypophysaires, et d’anomalies extrahypophysairesassociées. Les études fonctionnelles ont montré que cette mutation étaitresponsable d’un phénomène d’haplo-insuffisance. Cette nouvelle mutation permetd’enrichir le spectre phénotypique des patients chez lesquels doit être effectué unséquençage du gène LHX4 à la recherche d’étiologie de déficit hypophysaire combinémultiple.Identifier des mécanismes nécessaires au développement de l’axe thyréotrope. Dessouris exprimant une nouvelle recombinase Cre sous contrôle du promoteur de la Tshßont été croisées avec des souris transgéniques pour lesquelles les gènes de Pitx2 oud’Isl1 (2 facteurs de transcription impliqués dans le développement hypophysaire)étaient encadrés de séquences flox. Les modèles permettaient ainsi l’inactivation dePitx2 et Isl1 au sein des cellules thyréotropes au cours de l’embryogenèse. L’étudephénotypique retrouve un déficit de croissance compatible avec un déficit thyréotropepartiel en cas d’inactivation de Pitx2 : ce phénotype est probablement lié à unmécanisme compensateur assuré par PITX1, un facteur de transcription àhoméodomaine bicoïde possédant le même homéodomaine et domaine C terminal quePITX2. A l’inverse, l’inactivation de Isl& se traduit par un déficit thyréotrope complet. Lefait que les transcrits de l’ensemble des facteurs de transcription nécessaires audéveloppement de l’axe thyréotrope soient diminués dans ce modèle souligne le rôlemajeur de ISL1 dans la fonction et la maintenance de l’axe thyréotrope.Nos résultats permettent de mieux appréhender certains des nombreux mécanismes etfacteurs impliqués dans le développement hypophysaire chez la souris, et dans lapathologie hypophysaire chez l’homme. / Hypopituitarism is defined by one or several pituitary deficiencies. Congenital hypopituitarism is mostly due to transcription factors mutations. Our aims were to try to better identify some of the mechanisms involved in pituitary ontogenesis and pituitary diseases, mainly pituitary deficiencies: new pathways, new transcription factors, new mutations. - First we identified novel mechanisms necessary for the differenciation of the Pou1f1 lineages (ie somatolactotroph and thyrotroph cells). The role of TLE co-repressors is crucial, as they are able by themselves to inhibit the stimulatory actions of PROP1 on POU1F1 promoter. This is necessary to obtain a correct timing of differentiation during pituitary development (Carvalho, Brinkmeier, castinetti et al., Molecular Endocrinology, 2010). - Second, we showed the roles of 2 transcription factors, PITX2 and ISL1, in thyrotrophs maintenance and function. By using a new cre recombinase driven by the TSHb promoter, we managed to inactivate each of these transcription factors in the thyrotrophs. Inactivation of PITX2 led to a partial thyrotroph deficiency, counterbalanced by an overexpression of PITX1 (Castinetti et al., Molecular Endocrinology, submitted). Inactivation of ISL1 led to a complete thyrotroph deficiency (Castinetti et al., Molecular Endocrinology, in preparation). - Finally, we reported 1 new mutation of the LIM transcription factor LHX4, responsible for combined pituitary hormone deficiencies in a family. New phenotypic traits will help the physician improve the way to select which patients to screen for LHX4 mutations (Castinetti, Saveanu et al., JCEM, 2008).

Resumo: A hipófise anterior compõe-se de cinco tipos celulares que são definidos pelos hormônios que secretam. A diferenciação desses tipos celulares resulta de uma cascata temporalmente regulada de fatores transcricionais expressos no tecido hipofisário. Mutações de um desses fatores podem resultar tanto em defeitos estruturais da glândula como em deficiências hormonais, que podem ser isoladas (Déficit de hormônio do crescimento - DGH) ou combinadas (DHHC), dependendo do papel do fator transcricional mutado. A Displasia Septo - óptica (DSO) caracteriza-se pela presença de hipoplasia hipofisária, hipoplasia de nervo óptico e/ou má formações de estruturas da linha média. Foram avaliados 11 pacientes com quadro clinico de SOD, DGH e DHHC e realizado o sequenciamento genético do gene HESX1 desses indivíduos. Nos casos de DHHC foi feita uma análise adicional do gene PROP1. A mutação missense em estado de heterozigose A1772G levando a substituição N125S foi identificada em um paciente portador de DSO, no gene HESX1. Essa troca já foi previamente relatada como um polimorfismo na população Afro-Caribenha. Encontramos três pacientes portadores da variante alélica A9A e N20S no exon 1 do gene PROP1, já descritos previamente na literatura como polimorfismos. / Abstract: The anterior pituitary is made of five types of cell defined according to the hormones they secrete. Differentiation among such cell types derives from a cascade of temporally regulated transcriptional factors expressed in the pituitary tissue. Mutation in one of these factors may result in both structural gland defects and hormonal deficiencies, which may be either isolated (DGH - Growth Hormone Deficiency) or combined, depending on the role of the mutated transcriptional factor. Septo-optic dysplasia (SOD) is characterized by pituitary hypoplasia, optic nerve hypoplasia and/or malformation of medium line structures. Eleven patients with a clinical state of SOD, DGH and CPHD were assessed, and genetically sequenced for the HESX1 gene. For CPHD cases, an additional analysis for the PROP1 gene was also conducted. One SOD patient was found to have a missense mutation in A1772G heterozygosis state, leading to the N125S replacement, in HESX1 gene. Such replacement has already been reported as a polymorphism in the Afro-Caribbean population. We found three patients with the alelic variation A9S and N20A in exon 1 of PROP1 gene, previously described as polymorphisms. / Orientador: Célia Regina Nogueira / Coorientador: Denise Perone / Mestre

Genetic and Hormonal Regulation of Children's Growth MUDr. Jan Vosáhlo Abstract Growth in childhood is a complex process of changing the body, which can be disrupted by various illnesses including endocrine disorders, particularly growth hormone deficiency. Tumors or other processes affecting hypothalamic-pituitary area can be a postnatal cause of GHD; prenatal causes include 1) developmental disorders of the pituitary as part of complex syndromes, 2) developmental disorders of the pituitary due to defects in regulatory genes and 3) defects in genes involved in the synthesis and secretion of GH. The first topic of the thesis was septo-optic dysplasia - a complex syndrome involving optic nerve hypoplasia, structural brain abnormalities and pituitary dysfunctions. We extensively described phenotype in 11 Czech patients; we observed both complete SOD and incomplete forms variously combining two of the three main components of the syndrome. The cohort then became a part of an international study of 68 patients, in which we studied the phenotype in dependence on the brain morphology. We found correlation between the severity of clinical symptoms and the degree of septum pellucidum abnormities and also a correlation between hippocampus and falx abnormities and neurological symptoms. As the second topic we studied...

Genetic and Hormonal Regulation of Children's Growth MUDr. Jan Vosáhlo Abstract Growth in childhood is a complex process of changing the body, which can be disrupted by various illnesses including endocrine disorders, particularly growth hormone deficiency. Tumors or other processes affecting hypothalamic-pituitary area can be a postnatal cause of GHD; prenatal causes include 1) developmental disorders of the pituitary as part of complex syndromes, 2) developmental disorders of the pituitary due to defects in regulatory genes and 3) defects in genes involved in the synthesis and secretion of GH. The first topic of the thesis was septo-optic dysplasia - a complex syndrome involving optic nerve hypoplasia, structural brain abnormalities and pituitary dysfunctions. We extensively described phenotype in 11 Czech patients; we observed both complete SOD and incomplete forms variously combining two of the three main components of the syndrome. The cohort then became a part of an international study of 68 patients, in which we studied the phenotype in dependence on the brain morphology. We found correlation between the severity of clinical symptoms and the degree of septum pellucidum abnormities and also a correlation between hippocampus and falx abnormities and neurological symptoms. As the second topic we studied...

Le récepteur hypophysaire de la GnRH (RGnRH) joue un rôle crucial dans le contrôle de la fonctionde reproduction. Dans le promoteur distal du Rgnrh, j’ai caractérisé un élément de réponsebifonctionnel répondant aux protéines LIM à homéodomaine ISL1/LHX3 et à GATA2. D’autre part,deux motifs TAAT situés dans la région plus proximale confèrent à ce gène la capacité de répondreaux facteurs Paired-like PROP1 et OTX2. Tous ces facteurs, exprimés précocement au cours del’ontogenèse hypophysaire, pourraient participer à l’émergence de l’expression du Rgnrh. Hors del’hypophyse, j’ai découvert que le Rgnrh est exprimé au cours du développement postnatal dansl’hippocampe de rat, où il module la plasticité synaptique. Par ailleurs, j’ai identifié deux nouveauxsites d’expression, la rétine et la glande pinéale. Ces résultats mettent en lumière l’importancefonctionnelle de ce récepteur et de son ligand et les rôles multiples qu’il ont acquis au cours del’évolution des Vertébrés. / In the pituitary, the GnRH receptor (GnRHR) plays a crucial role in the neuroendocrine control ofreproductive function. Within the distal region of the Gnrhr promoter, I have characterized abifunctional response element modulated by the LIM homeodomain proteins ISL1/LHX3 and byGATA2. Besides, in the proximal region of the promoter, two TAAT motifs conferred response toPaired-like factors PROP1 and OTX2. All these factors are expressed during pituitary ontogenesis andcould participate in the onset and regulation of Gnrhr expression. Outside of the pituitary, I havediscovered that the Gnrhr was expressed during postnatal development in the rat hippocampus, whereit modulated synaptic plasticity. Furthermore, I have identified two novel sites of Gnrhr expression, theretina and the pineal gland. Altogether, these data highlight the functional importance of this receptorand its ligand as well as the multiple roles they have acquired during vertebrate evolution.