Les modifications post-traductionelles des histones contribuent à l’expression génique et à la stabilité du génome. La méthylation de la lysine 4 de l’histone H3 (H3K4me), une marque associée aux promoteurs de gènes transcrits, est déposé par les methyltransferases hautement conservées de la famille SET1, dans le contexte du complexe COMPASS. SET-2, l’homologue de SET1 chez Caenorhabditis elegans, est responsable de la déposition de H3K4me dans la lignée germinale, et son inactivation provoque une perte progressive de la fertilité. Le but de mon travail de thèse a été d’étudier comment SET-2 et la méthylation de H3K4 contribuent au maintien de la lignée germinale. J’ai montré que l’absence de SET-2 provoque une sensibilité accrue aux dommages à l’ADN. Cependant, les voies de signalisation et de réparation de ces dommages sont fonctionnelles dans le mutant set-2. Par séquençage de l’ADN, j’ai par ailleurs montré que la stérilité progressive observée en l’absence de set-2 n’est pas due à une capacité de réparation réduite. L’ensemble de mes résultats suggère que H3K4me pourrait agir en aval de la signalisation de dommages à l’ADN, en influençant l’organisation de la chromatine aux sites des cassures double brin. J’ai d’autre part mis en évidence une nouvelle fonction pour la méthylation de H3K4 dans l’organisation de la chromatine en montrant que set-2 interagit génétiquement avec le complexe Condensine II et la Topoisomérase II, facteurs clefs de l’organisation mitotique des chromosomes. Des expériences de microscopie par FLIM-FRET ont d’ailleurs validé une fonction de H3K4 méthylée dans l’organisation de la chromatine dans la lignée germinale. Enfin, j’ai montré par analyses transcriptomiques que la protéine CFP-1 du complexe COMPASS est impliquée dans la régulation du programme transcriptionnel de la lignée germinale et que cette fonction est indépendante de SET-2. L’ensemble de mes résultats montre comment la régulation chromatinienne impacte le maintien d’une lignée germinale fonctionnelle à plusieurs niveaux. / Post-translational modifications of histones contribute to gene expression and genome stability. Methylation of lysine 4 of histone H3 (H3K4me), a mark associated with actively transcribed genes, is deposited by the highly conserved SET1 family methyltransferases acting in COMPASS related complexes. SET-2, the SET1 homologue in Caenorhabditis elegans, is responsible for the deposition of H3K4me in the germ line, and its inactivation causes progressive loss of fertility. The purpose of my PhD work was to study how SET-2 and the methylation of H3K4 contribute to the maintenance of the germ line. I have shown that the absence of SET-2 causes increased sensitivity to DNA damage. However, the DNA damage-induced signaling and repair pathways are functional in the set-2 mutant. By DNA sequencing, I have also shown that the progressive sterility observed in the absence of set-2 is not due to a reduced repair capacity. Together, my results suggest that H3K4 methylation may act downstream of DNA damage signaling, potentially by influencing the organization of chromatin at the sites of double-strand breaks. I have also described a new function for H3K4 methylation in the organization of chromatin by showing that set-2 genetically interacts with the Condensitin II complex and Topoisomerase II, key factors in mitotic chromosome organization. Moreover, FLIM-FRET microscopy experiments have validated a role for H3K4 methylation in germline chromatin organization. Finally, using transcriptomic analyses, I have described a function for CFP-1, a component of the COMPASS complex, in the regulation of the germline transcriptional program independent of SET-2. Altogether, my results show how chromatin regulation affects the maintenance of a functional germline through multiple mechanisms.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2016-09-12T16:26:18Z No. of bitstreams: 2 Dissertação - Natália Beatriz Viana Teixeira - 2014.pdf: 4643049 bytes, checksum: d059f552aeb8aa7dfff25ae7c2580050 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-15T12:50:11Z (GMT) No. of bitstreams: 2 Dissertação - Natália Beatriz Viana Teixeira - 2014.pdf: 4643049 bytes, checksum: d059f552aeb8aa7dfff25ae7c2580050 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-15T12:50:11Z (GMT). No. of bitstreams: 2 Dissertação - Natália Beatriz Viana Teixeira - 2014.pdf: 4643049 bytes, checksum: d059f552aeb8aa7dfff25ae7c2580050 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-07-04 / In this research I review the discourses of legitimation of CFP Resolution No. 1/99 (Res 1/99), and I seek answer in part: how a discursive practice that made real this policy worked out among other practices discursive, legal and political order? To do this, I analyze discourses present in the relationship between favorable and contrary statements to their institution, from the texts (1) of the res itself. 1/99; (2) Public Civil Action 2011.51.01.018794-3 filed by Judicial Session of Rio de Janeiro – MPF; (3) the PDC 234/11; (4) the CFP institutional site of news about the res. 1/99; (5) Selection of news CFP contrary to the Resolution No. 1/99 on the internet; and (6) Images of street manifestations, cartoons and memes available on the internet related to the negative reactions to the PDC 234/11. We employ a search method inspired by Foucault's archeology and genealogy; and describe happenings previous to the Res 1/99, that support their emergency related to the emergence of homosexuality as a pathology and their displacement to normality. I analyze the co-dependence between state, science and profession mutually legitimate in modern societies; I point limits of Res 1/99 as a strategy of resistance before the heteronormative regime; and, finally, outline how the identity polarization between gays and evangelicals demarcates and reifies victimization strategies, homogenization and integration that characterize the present intensification of social tension and intolerance. / Nesta pesquisa analiso os discursos de legitimação da Resolução CFP nº 1/99 (Res. 1/99), e busco responder parcialmente como a prática discursiva que positivou esta norma funcionou entre outras práticas de ordem discursiva, jurídica e política. Para isso, parto de discursos presentes na relação entre enunciados favoráveis e contrárias à sua instituição, a partir dos textos (1) da própria res. 1/99; (2) da Ação Civil Pública 2011.51.01.018794-3 movida pela Sessão Judiciária do Rio de Janeiro do MPF; (3) do PDC 234/11; (4) das notícias no site institucional do CFP sobre a res. 1/99; (5) de seleção de notícias contrárias à Resolução CFP nº 1/99 na internet; e (6) de imagens de manifestações de rua, charges e memes disponíveis na internet relacionadas às reações contrárias ao PDC 234/11. Emprego um método de pesquisa inspirado na arqueologia e genealogia foucaultiana; e descrevo acontecimentos antecedentes à Res. 1/99, que embasam sua emergência, relacionados à emergência da homossexualidade como patologia e seu deslocamento à normalidade. Analiso a co-dependência entre Estado, ciência e profissão que se legitimam mutuamente nas sociedades modernas; aponto limites da Res. 1/99 enquanto estratégia de resistência diante do regime heteronormativo; e, por fim, esboço como a polarização identitária entre gays e evangélicos demarca e reifica estratégias de vitimização, homogeneização e integração que caracterizam o atual acirramento da tensão e intolerância social.