La préservation d’un stock de cellules souches fonctionnelles est indispensable pour le maintien de nombreux tissus chez l’adulte. Les cellules souches se multiplient pour s’auto-renouveller et entrent en différenciation donnant naissance à des progéniteurs puis à des cellules matures. Récemment, la possibilité pour les progéniteurs de se reprogrammer en cellules souches et de réacquérir un potentiel de régénération à long terme a été suggérée notamment dans le tissu germinal. Ainsi, l’auto-renouvellement et la reprogrammation des progéniteurs pourraient jouer un rôle dans le maintien du pool de cellules souches. Mon travail de thèse portait sur l’étude de ces deux mécanismes de régénération des cellules souches chez la souris. J’ai tout d’abord étudié la reprogrammation des progéniteurs germinaux au cours de la spermatogenèse. Ce travail montre la capacité des progéniteurs germinaux mâles, les spermatogonies différenciées, à modifier leur programme de différenciation et à générer de nouvelles cellules souches germinales après transplantation testiculaire. Les progéniteurs germinaux pourraient ainsi constituer une réserve de « cellules souches potentielles ». Le tissu germinal possède donc une certaine plasticité. La seconde partie de mon travail porte sur l’implication du gène Fancg de l’anémie de Fanconi, voie de réponse aux dommages à l’ADN, dans l’auto-renouvellement et la fonctionnalité des cellules souches hématopoïétiques au cours de l’hématopoïèse. L’intégrité génétique des cellules souches doit en effet être préservée tout au long de la vie de l’individu. Cette étude montre que l’invalidation du gène Fancg perturbe le processus de migration, la quiescence, et la régulation de l’expression de certains gènes clés des fonctions des cellules souches. Ces altérations participent au déficit fonctionnel des cellules souches hématopoïétiques observées dans le modèle murin Fancg-/-. / The long-term maintenance of the stem cell pool is necessary to preserve the functionality of an organ throughout life. Stems cells proliferate in order to selfrenew or to be committed to differentiate to produce progenitors and finally highly specialized cells. Recent reports have suggested that germinal progenitors could reprogram into stem cells and reacquire a potential to regenerate tissue at long-term. Thus, the stem cell selfrenewal process and the reprogramming of progenitors could play a role in the maintenance of the stem cell pool. The project of my thesis focused on those two mechanisms of stem cell regeneration in the mouse model. First, I investigated the reprogramming process of the germinal progenitors during spermatogenesis. Our results show that male germinal progenitors, the differentiating spermatogonia, can change their differentiation program and generate new functional germinal stem cells after testicular transplantation. The germinal progenitors could constitute a pool of potential stem cell, and underscores the plasticity of the germinal lineage. A second part of my project dealt with the involvement of fancg, a gene of the Fanconi anemia DNA damage response pathway, in the selfrenewal and in the functions of the hematopoietic stem cells. The maintenance of the genetic integrity throughout life is particulary important for stem cells in order to safeguard the stem cell pool. Our study show that fancg deficiency induces the impairment of the migration potential and of the quiescence of stem cells, and modifies the expression of several key genes regulating stem cell functions. Those alterations contribute to the functional impairment of the hematopoietic stem cells observed in Fancg-/- mice.

Orientador: Helena Zerlotti Wolf Grotto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-07T22:39:50Z (GMT). No. of bitstreams: 1 Souza_LaudiceiaRodriguesde_M.pdf: 1702960 bytes, checksum: 3ba7c0babaf3b3aaba833310422371ed (MD5) Previous issue date: 2006 / Resumo: O papel da inflamação na fisiopatologia da anemia falciforme tem sido alvo de recentes investigações. O processo obstrutivo que ocorre na microcirculação, causado pelo acúmulo de células falcizadas, leva à lesão do endotélio, com migração e adesão de leucócitos, liberação de radicais oxigênio, liberação e ativação de citocinas inflamatórias. É reconhecida a participação de diversas citocinas na eritropoiese, estimulando ou inibindo a produção de células eritróides pela medula óssea, em especial na anemia que acompanha as doenças inflamatórias/infecciosas crônicas. É reconhecida a ação inibitória do interferon gama (IFN-?) sobre as células progenitoras da medula óssea, além de sua participação nos distúrbios do metabolismo do ferro (Fe), presentes na anemia de doença crônica. A Neopterina (NP) é um marcador associado à imunidade celular produzido pelos monócitos/macrófagos quando estimulados pelo IFN-?. Os dados sobre a participação do IFN-? no processo inflamatório que acompanha a Doença Falciforme são contraditórios e se restringem à Anemia Falciforme (Hb SS). O objetivo deste trabalho foi estudar a participação da Interleucina-3 (IL-3), do IFN -? e da NP em pacientes com Hb SS e hemoglobinopatia SC (Hb SC) na fase estável da doença, a fim de verificar a possível ação dessas citocinas e da NP sobre o metabolismo do Fe e da hematopoiese. Nossos resultados mostraram que as concentrações de IL-3 foram mais altas nos grupos SS e SC em relação ao controle, enquanto as determinações de IFN-? não mostraram diferenças entre os grupos. Pacientes SS com hemoglobina Fetal (Hb F) > 8,5% mostraram valores de IL-3 significativamente mais elevados do que aqueles com Hb F < 8,5% (p= 0,0338). Não foi observada correlação entre os parâmetros inflamatórios e do metabolismo do Fe. Uma correlação direta foi observada somente nos pacientes SS entre os níveis de IL-3 e hemoglobina (Hb) (r= 0,4633, p= 0,0457), IL-3 e Hb F (r= 0,6011, p= 0,0065). Os níveis de NP foram significativamente mais elevados nos pacientes SS e SC do que nos controles, mas não houve diferença entre os 2 grupos de pacientes. Não houve correlação entre NP e os parâmetros relacionados ao metabolismo de Fe. Esses dados sugerem que a IL-3 tem ação estimulante sobre a produção de Hb F e que pacientes com Hb SS, mesmo na fase estável da doença apresentam um certo grau de ativação do sistema monócito/macrófago, representado pelos altos níveis de NP, o que provavelmente contribui para a condição inflamatória crônica desses pacientes / Abstract: Sickle cell disease (SCD) has been recognized as a chronic inflammatory condition. Cytokines are released in response to stress or pathological situations and have influence on hematopoiesis. The aim of this study was to evaluate Interleukin-3 (IL-3), Interferon-? (IFN-?) and neopterin (NP) levels in steady state patients with sickle cell anemia (SS) (n= 38) and SC hemoglobinopathy (n= 17), in order to verify the possible action of those cytokines and NP on iron metabolism and hematopoiesis. Serum IL-3 concentration was higher in SS and SC groups than in controls, whereas IFN-? determinations were not different among groups. SS patients presenting HbF= 8.5% showed IL-3 levels significantly higher than those with HbF< 8.5% (p= 0.0167). No correlation was observed among inflammatory and iron metabolism parameters. It was observed a significant correlation between IL-3 and Hb levels (r= 0.4201, p= 0.0086) and a negative correlation between IL-3 and reticulocyte counting (r= - 0.4019, p= 0.0124) only in SS group. NP levels were significantly higher in SS group than in control (p< 0.0001), but not different between SSxSC and SCxControl. No correlation was observed between NP and iron metabolism parameters. In conclusion, it was confirmed that IL-3 stimulates hematopoiesis and that SS patients, even in steady-state, presenting macrophage/monocyte activation, represented by high levels of NP, that probably contributes to chronic inflammatory condition / Mestrado / Ciencias Biomedicas / Mestre em Ciências Médicas

Kazunori Yoshikiyo, Katja Kratz, Kouji Hirota, Kana Nishihara, Minoru Takata, Hitoshi Kurumizaka, Satoshi Horimoto, Shunichi Takeda, and Josef Jiricny "KIAA1018/FAN1 nuclease protects cells against genomic instability induced by interstrand cross-linking agents" PNAS 2010 107 (50) 21553-21557; published ahead of print November 29, 2010, doi:10.1073/pnas.1011081107 / 京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12772号 / 論医博第2063号 / 新制||医||1000(附属図書館) / 30755 / (主査)教授 小松 賢志, 教授 小川 誠司, 教授 松本 智裕 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(医学) / 甲第23372号 / 医博第4741号 / 新制||医||1051(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 滝田 順子, 教授 髙折 晃史, 教授 江藤 浩之 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Background. Clinical management of families with autosomal recessive genetic disorders focuses almost exclusively on the affected family members. However, clinically unaffected members of such families may also be severely troubled by the serious illness in a family member. The purpose of this study was to explore the experiences of healthy siblings of patients with a chronic genetic disease, Fanconi Anemia (FA). Procedure. We used a qualitative, descriptive design, which consisted of in-depth, semi-structured interviews. A convenience sample of nine siblings of patients with FA was recruited from a National Cancer Institute clinical research protocol, which targets families with inherited bone marrow failure syndromes. NVivo 2.0 software facilitated qualitative content analysis of the data. Results. Siblings' rich descriptions provided novel insights into the intricate hardships of living within a family in which a rare, life-threatening, chronic genetic illness in one member is the focus of daily life. Four major themes of the sibling experience emerged from the interview data: (1) containment, (2) invisibility, (3) worry, and (4) despair. Conclusions. Our data suggest that unrecognized psychosocial issues exist for the apparently healthy siblings of patients with FA. This study explores the psychosocial consequences of living in a family with FA and one of only a few studies to explore the sibling experience of chronic illness using a contemporaneous approach. These findings support the need for an increased awareness among health care providers; future hypothesis driven investigation, and improved assessment of problems with potential psychological morbidity.

Indiana University-Purdue University Indianapolis (IUPUI) / Fanconi Anemia (FA), a chromosomal instability syndrome, is characterized by bone marrow failure, genetic malformations, and predisposition to malignancies like acute myeloid leukemia (AML) and solid tumors. FA is caused by germline bi-allelic mutations in one of 21 known FA pathway genes and somatic mutations in FA genes are also found in a variety of sporadic cancers. Recently, numerous reports have discovered that the protective function of the FA pathway extends beyond its canonical role in regulation of DNA repair in interphase. In particular, the FA pathway has been shown to function in essential mitotic processes including spindle assembly checkpoint (SAC), cytokinesis, and centrosome maintenance. Understanding of the mechanistic origins of genomic instability leading to carcinogenesis and bone marrow failure has important scientific and clinical implications. To this end, using a micronucleus assay, we showed that both interphase DNA damage and mitotic errors contribute to genomic instability in FA ex vivo and in vivo. Functional studies of primary FA patient cells coupled with super-resolution microscopy revealed that FANCA is important for centrosome dependent spindle assembly supporting the protective role of FA pathway in mitotic processes. Furthermore, we dissected the interactions between the FA pathway and cellular kinase networks by employing a synthetic lethality sh-RNA screen targeting all human kinases. We mapped kinases that were synthetically lethal upon loss of FANCA, particularly those involved in highly conserved signal transduction pathways governing proliferation and cell cycle homeostasis. We mechanistically show that loss of FANCA, the most abundant FA subtype, results in in premature degradation of the mitotic kinase BUBR1 and faster mitotic exit. We further demonstrate that FANCA is important for PCAF-dependent acetylation of BUBR1 to prevent its premature degradation. Our results deepen our understanding of the molecular functions of the FA pathway in mitosis and uncover a mechanistic connection between FANCA and SAC phosphosignaling networks. These findings support the notion that further weakening the SAC through targeting kinases like BUBR1 in FA-deficient cancers may prove to be a rational therapeutic strategy.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19269号 / 医博第4033号 / 新制||医||1011(附属図書館) / 32271 / 京都大学大学院医学研究科医学専攻 / (主査)教授 岩井 一宏, 教授 髙折 晃史, 教授 山田 亮 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20668号 / 医博第4278号 / 新制||医||1024(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 武田 俊一, 教授 岩井 一宏, 教授 清水 章 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

Fanconi anemia (FA) is a genome instability syndrome that is clinically manifested by bone marrow failure, congenital defects, and elevated cancer susceptibility. The FA pathway is known to regulate the repair of DNA interstrand crosslinks in part through DNA homologous recombination (HR) repair. Up to today 16 FA proteins have been discovered that may participate in the common pathway. Cells that have mutations in the FA genes are hypersensitive to DNA damaging agents and display chromosome instability. A key regulatory event in the FA pathway is monoubiquitination of FANCD2-FANCI heterodimer that is mediated by a multi-component E3 ubiquitin ligase complex called FA core complex. Current model suggests that once the FANCD2-FANCI heterodimer is monoubiquitinated it relocates to chromatin where it interacts with other key repair proteins to facilitate DNA repair. More than 90% of the FA cases are presumed to be associated with defects in the monoubiquitination reaction, suggesting the significance of the modification in the pathogenesis of the disease. Despite the significance, the molecular interplay between the FA core complex and the FANCD2-FANCI heterodimer remains enigmatic. We are interested in the assembly mechanism of the various FA subcomplexes into the core complex, and we are actively investigating how the FANCD2-FANCI heterodimer is recruited to these putative subcomplexes. As the FA pathway is a crucial determinant for cellular resistance to DNA damaging agents, there have been hypotheses that disruption of this pathway may be beneficial in enhancing chemosensitivity of certain cancer cells. In collaboration with Dr. Cai’s chemistry lab, we will develop a screen platform to identify a small molecules to interrupt the monoubiquitination reaction. Completion of these studies will enhance the much-needed knowledge of the key enzymatic reaction in the pathway, and perhaps the information can be used for development of novel chemotherapeutic strategies.