Le domaine Dlk1-Dio3 est l’un des rares domaines imprimés contrôlés par une région de contrôle d'impression méthylée sur le chromosome paternel, nommée IG-DMR. Dans l’embryon, au niveau du domaine Dlk1, Rtl1 et Dio3 les gènes codant pour des protéines sont exprimés à partir du chromosome paternel, tandis que les ARNs non-codants dont Meg3, les snoRNAs à boite C/D et les micro-ARNs sont exprimés à partir du chromosome maternel.Il a été montré que la copie maternelle de l'IG-DMR est nécessaire pour l'expression des gènes imprimés de ce domaine et que les ARNs de types enhancer (de la même région) activent la transcription des ARNs non-codants. Cependant, les mécanismes qui régulent l'expression imprimée de gènes codant pour des protéines restent indéterminés. Dans ce projet, nous avons cherché à élucider les mécanismes qui contrôlent l'expression spécifiquement paternelle des gènes codant pour des protéines ainsi que le rôle possible des ARNs non-codants dans ce processus.Pour nos études alléliques, nous avons utilisé des cellules ES hybrides qui ont été obtenues en croisant des lignées de M. musculus domesticus et M. musculus molossinus. Ces cellules ont été différenciées in vitro dans des lignées neurales. Dans les cellules ES, l'expression Dlk1 est détectée à partir des deux chromosomes parentaux à des niveaux très bas. Lors de la différenciation, l'allèle paternel de Dlk1 devient actif tandis que le niveau d'expression de l'allèle maternel reste faible. Nos études de la chromatine ont montré que cette surexpression est due à l’activation de la chromatine sur l'allèle paternel de Dlk1.L'un de nos objectifs était d'explorer le rôle de Meg3 (un long ARN non-codant) dans la régulation de l’empreinte de Dlk1. A cet effet, nous avons généré des cellules souches embryonnaires déficientes en Meg3. Dans toutes les lignées déficientes, de suppressions maternelles ou bi-alléliques, nous avons constaté une perte d’expression de tous les ANRs non-codants. De plus, l’expression de Dlk1 devient bi-allélique dans ces cellules. Pour élucider le mécanisme de l'empreinte de ce gène, nous avons décidé d'étudier les caractéristiques de la chromatine au niveau du promoteur Dlk1 dans les cellules déficientes en Meg3. Nous avons examiné les modifications activatrices et répressives des histones ainsi que l'occupation de l'ARN Pol II. Nous avons observé l'acquisition des marques d’une chromatine active sur les deux chromosomes ainsi que le recrutement bi-allélique de l'ARN Pol II.Bien que nous n’ayons pas pu détecter une perte de la marque répressive H3K27me3 suite à la surexpression de Dlk1, nous avons observé un gain d'acétylation sur ce résidu lysine. Afin de comprendre davantage le rôle de la marque H3K27me3 sur l’empreinte de Dlk1, nous avons généré des cellules ES dépourvues de EZH2, la méthyltransférase de H3K27. L’expression de Dlk1 dans les cellules différenciées dépourvues de H3K27me3 est bi-allélique.Enfin, ces données suggèrent que l'expression des ARNs non-codant empêche l'activation de Dlk1 sur le chromosome maternel via l’activité de EZH2 au cours du développement. / The Dlk1-Dio3 imprinted domain is one of the few imprinted domains that are controlled by a paternally methylated imprinting control region, IG-DMR. Protein-coding genes of the domain, Dlk1, Rtl1 and Dio3 are expressed from the paternal chromosome, and non-coding RNAs (ncRNAs) including Meg3, C/D box snoRNAs and microRNAs are expressed from the maternal chromosome exclusively in the embryo. Maternal copy of the IG-DMR is required for the imprinted gene expression at this domain. Enhancer RNAs transcribed from this region are involved in activation of ncRNA expression on the maternal chromosome. However, the regulation of imprinted expression of protein-coding genes remains unknown. In this project, we aimed to elucidate the mechanisms controlling the paternal specific expression of protein-coding genes and a possible role of ncRNAs in this process.For our allelic studies, we made use of hybrid ES cells that were obtained by crossing M. musculus domesticus and M. musculus molossinus strains. These cells were differentiated in vitro into neural lineages. In ES cells, Dlk1 expression is detected from both parental chromosomes at very low levels. Upon differentiation, paternal allele of Dlk1 gets activated while low level of expression is detected from maternal allele. Our chromatin studies showed that this upregulation is through the acquisition of active chromatin on the paternal allele of Dlk1.One of our aims was to explore the role of Meg3 long non-coding RNA (lncRNA) in the regulation of Dlk1 imprinting. For this purpose, we generated ES cells deficient in Meg3. In all maternal or biallelic deletion lines, we observed complete loss of all ncRNA expression. Interestingly, in these cells Dlk1 expression becomes biallelic. To elucidate the mechanism of imprinting of this gene, we set out to study the chromatin features at the Dlk1 promoter in Meg3 deficient cells. We looked into active and repressive histone modifications and RNA Pol II occupancy. We observed acquisition of active chromatin marks on both chromosomes as well as biallelic recruitment of RNA Pol II.Although we could not detect a loss of repressive mark H3K27me3 upon Dlk1 upregulation on the paternal allele, we observed gain of acetylation on this lysine residue. To further investigate the role of H3K27me3 mark on Dlk1 imprinting, we generated ES cells that lack functional EZH2, the H3K27 methyltransferase. Dlk1 is biallelically expressed in the differentiated cells that are devoid of H3K27me3.Combined, these data suggest a model in which non-coding RNA expression prevents the developmental activation of Dlk1 on the maternal chromosome by a process that also requires the activity of EZH2.

Recently, long non-coding RNAs (lncRNAs) emerged as important regulators of many cellular functions. Many nuclear lncRNAs regulate the expression of geomically proximal or overlapping protein coding genes. Less clear is whether intergenic lncRNAs can regulate transcription by modulating chromatin at genomically distant loci in an RNA-dependent manner. This thesis investigated molecular functions of Dali, an intergenic central nervous system expressed lncRNA conserved in therian mammals. Dali is transcribed from a locus 50 kb downstream of the Pou3f3 transcription factor gene and performs both genomically local and distal RNA-dependent roles. Its depletion disrupts the differentiation of neuroblastoma cells. Locally, Dali regulates transcription of the Pou3f3 locus. Distally, it preferentially binds near to and regulates active promoters across the genome, including by physically associating with the POU3F3 transcription factor. Dali also interacts with the DNMT1 DNA methyltransferase in mouse and human and regulates CpG island-associated promoters by modulating their DNA methylation levels in trans. This work is the first to demonstrate that a lncRNA can regulate the DNA methylation of CpG island-associated promoters in trans and one of the first large scale studies to identify direct transcriptional targets of a lncRNA genome-wide. It also provides a more detailed molecular dissection of the extended Pou3f3 locus and a framework for the prioritisation and comprehensive functional characterisation of nuclear lncRNAs.

Human neurodevelopment requires the coordinated expression of thousands of genes, exquisitely regulated in both spatial and temporal dimensions, to achieve the proper specialization and inter-connectivity of brain regions. Consequently, the dysregulation of complex gene networks in the developing brain is believed to underlie many neurodevelopmental disorders, such as autism spectrum disorders (ASD). Autism has a significant genetic etiology, but there are hundreds of genes implicated, and their functions are heterogeneous and complex. Therefore, an understanding of shared molecular and cellular pathways underlying the development ASD has remained elusive, hampering attempts to develop common diagnostic biomarkers or treatments for this disorder. I hypothesized that analyzing functional genomics relationships among ASD candidate genes during normal human brain development would provide insight into common cellular and molecular pathways that are affected in autistic individuals, and may help elucidate how hundreds of diverse genes can all be linked to a single clinical phenotype. This thesis describes a coordinated set of bioinformatics experiments that first (i) assessed for gene expression and co-expression properties among ASD candidates and other non-coding RNAs during normal human brain development to discover potential shared mechanisms; and then (ii) directly assessed for changes in these pathways in autistic post-mortem brain tissue. The results demonstrated that when examined in the context of normal human brain gene expression during early development, autism candidate genes appear to be strongly related to the neurodevelopmental pathways of synaptogenesis, mitochondrial function, glial cytokine signaling, and transcription/translation regulation. Furthermore, the known sex bias in ASD prevalence appeared to relate to differences in gene expression between the developing brains of males and females. Follow up studies in autistic brain tissue confirmed that changes in mitochondrial gene expression networks, glial pathways, and gene expression regulatory mechanisms are all altered in the brains of autistic individuals. Together, these results show that the heterogeneous set of autism candidate genes are related to each other through shared transcriptional networks that funnel into common molecular mechanisms, and that these mechanisms are aberrant in autistic brains.

Myoclonus-Dystonia (MD) is an inherited, rare, autosomal dominant movement disorder characterized by quick, involuntary muscle jerking or twitching (myoclonus) and involuntary muscle contractions that cause twisting and pulling movements, resulting in abnormal postures (dystonia). The first MD locus was mapped to 7q21-q31 and called DYT11; this locus corresponds to the SGCE gene. Our group previously identified a second MD locus (DYT15) which maps to a 3.18 Mb region on 18p11. Two patients were chosen to undergo next-generation sequencing, which identified 2,292 shared novel variants within the critical region. Analysis of these variants revealed a 3 bp duplication in a transcript referred to as CD108131, which is believed to be a long non-coding RNA. Characterization of this transcript determined that it is 863 bp in size, it is ubiquitously expressed, with high expression in the cerebellum, and it accounts for ~3% of MD cases.

A visao sobre o dogma central da biologia molecular passou por aperfeicoamentos na virada deste seculo. Muito se deve ao interesse por pesquisas feitas para compreensao do que ate entao eram regioes do genoma conhecidas como DNA Lixo. Neste contexto, projetos de transcriptoma, avancos em tecnologias de sequenciamento, bem como analises em bioinformatica, contribuiram para elucidar o que estava sendo transcrito. Tais regioes foram denominadas como RNAs nao-codificadores ou non-coding RNA (ncRNA) que eram transcritas, mas nao traduzidas em proteinas. Apesar da quantidade de metodos para o estudo in silico dos ncRNAs, existem lacunas a serem preenchidas nas pesquisas desta molecula, tais como: metodos de anotacao em geral, caracterizacao de novas classes e mecanismos alternativos de busca por similaridade de sequencia primaria. Alem disso, nao se havia uma ferramenta que reunisse num unico local as informacoes dos bancos de dados publicos de ncRNA disponiveis. Neste trabalho, buscou-se preencher tais lacunas, contribuindo para o desenvolvimento de metodos computacionais nas pesquisas em ncRNAs. Foram utilizados os genomas de Hymenoptera e Diptera como sistema biologico para aplicar e testar os metodos desenvolvidos. / The classical vision of the central dogma of molecular biology was not changes dramatic until the end of the 20th century. At this time the scientific communities were interesting to understand what have in the regions of the genome known as \"Junk DNA\". Transcriptome projects together with sequencing Technologies anda bioinformatics analysis help to elucidate that this transcripts were regions that do not coding proteins and maybe has function. These transcripts are called non-coding RNA (ncRNA). Although there are a lot of computational approaches to the in silico research of ncRNA, there is a gap of research about this molecule such: approaches to the general annotation of ncRNA; identification of new classes of ncRNA; and alternatives search mechanisms of ncRNA. Besides that, there are not any central repository of public non-coding RNA databases that could help search for the information about it. In this report, we fill this gap. We tried to contributing to the development of computational methods in research on ncRNAs. We also used the Hymenoptera and Diptera genomes as a biological system to apply and test our developed approaches.

This mini-review investigates and compiles the latest knowledge regarding epigenetic changes on the mammalian mitochondrial DNA and its proteins. Methylation of the DNA, acetylation of the proteins and silencing of genes by short non-coding RNAs are the main epigenetic changes known today to affect mitochondrial DNA, mostly leading to repression. Methylation mainly occurs at non-CpG sites in the main non-coding region called the D-loop, with methylation patterns being cell type specific. Acetylation of proteins are mainly controlled by the deacetylase SIRT3, with its function being correlated to longevity. On the other hand, mitochondrial dysfunction is directly associated with a plethora of diseases, such as neurodegenerative disorders and heart disorders. The mitochondrion and nucleus are immensely dependent on each other and exchange vital proteins and RNAs, with epigenetic changes on one potentially affecting the other. Recent research shows that heteroplasmy is a proven cause of mitochondrial malfunction and that paternal inheritance is possible. The mitochondrial haplotype also shows different vulnerability to certain diets and diseases, leading to the conclusion that the mitochondrial haplotype can be used to more than just tracing human origins, such as to predicting and preventing diseases.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第22797号 / エネ博第411号 / 新制||エネ||79(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 片平 正人, 准教授 小瀧 努, 教授 森井 孝 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

Les cancers bronchopulmonaires non à petites cellules (CBNPC) sont la première cause de décès par cancer, les adénocarcinomes étant la forme la plus fréquente. Malgré une prise en charge précoce, ils constituent, par leur taux de récidive important et leur mauvais pronostic, un véritable problème de santé publique. Nous nous intéressons à l'hypoxie, un facteur agressivité des ADC, et à la famille des longs ARNs non codants (lncARNs), dérégulés dans de nombreux cancers et en réponse à l'hypoxie, mais peu caractérisés sur le plan structural et fonctionnel. Ces transcrits représentent un espoir pour le développement de nouvelles thérapies. Au cours de ma thèse, j'ai identifié une dizaine de lncARNs régulés par l'hypoxie in vitro et in vivo dans des ADC de stades précoces. j'ai caractérisé NLUCAT1, un transcrit nucléaire induit par l'hypoxie. L'invalidation de ce transcrit par le système CRISPR/Cas9 a révélé une diminution de la prolifération et de l'invasion cellulaires, et une augmentation du stress oxydatif et de la sensibilité au cisplatine, traduisant un potentiel rôle pro-oncogénique de ce transcrit dans les ADC. L'analyse du transcriptome a révélé une répression des réseaux de gènes contrôlés par NRF2, HIF et NFkβ dans les cellules déficientes pour NLUCAT1. Nous avons notamment identifié des gènes de la réponse anti-oxydante régulés par NRF2 dont l'ARN interférence mime en partie les conséquences de l'inactivation de NLUCAT1 sur l'apoptose. Nos résultats démontrent que NLUCAT1 exerce des activités pro-tumorales dans les ADC et suggère qu'il pourrait représenter une cible thérapeutique potentielle dans ce type de cancer. / Non Small Cell Lung Cancer (NSCLC) is the leading cause of cancer death worldwide, with poor prognosis and a high rate of recurrence despite early surgical removal. It is therefore essential to identify new prognostic markers and new therapeutic targets. We are interested in gene regulation related to hypoxia, a factor associated with relapse of lung adenocarcinomas (LUAD). The roles of long non coding RNAs (incRNAs) in cancer development and hypoxic response are largely unexplored. A transcriptome profiling of early-stage LUAD samples indicated that a set of incRNAs was correlated to a metagene hypoxic signature. Some of these transcripts were also sensitive to hypoxia in LUAD cell lines. We focused on a new "hypoxaLinc", named NLUCAT1 that is strongly up-regulated by hypoxia in vitro and correlated to hypoxic markers and bad prognosis in LUAD samples. Full molecular charactherization of NLUCAT1 showed that LUCAT1 is mainly regulated by NF-kβ and NRF2 transcription factors. Targered deletion of NLUCAT using CRISPR/CAS9 in A549 LUAD cell line, revelated a decrase in proliferative and invasive properties, an increase in oxidative stress and a higher sensisivity to displatin-induced apoptosis. We identified genes of the NRF2-regulated and anti-oxidant response whose RNA interference partially mimicked the consequences of NLUCAT1 inactivation on ROS-dependent caspase activation. Overall, our data strongly demonstrate that NLUCAT1 exerts pro-tumoral activities in early stages hypoxic LUADs ans suggest it could represent a new potential therapeutic target in lung cancer.

Teleost fishes share a duplication of their entire genomes. We report here on a computational survey of structured non-coding RNAs (ncRNAs) in teleost genomes, focusing on the fate of fish-specific duplicates. As in other metazoan groups, we find evidence of a large number (11,543) of structured RNAs, most of which (~86%) are clade-specific or evolve so fast that their tetrapod homologs cannot be detected. In surprising contrast to protein-coding genes, the fish-specific genome duplication did not lead to a large number of paralogous ncRNAs: only 188 candidates, mostly microRNAs, appear in a larger copy number in teleosts than in tetrapods, suggesting that large-scale gene duplications do not play a major role in the expansion of the vertebrate ncRNA inventory.

Genome-wide multiple sequence alignments (MSAs) are a necessary prerequisite for an increasingly diverse collection of comparative genomic approaches. Here we present a versatile method that generates high-quality MSAs for non-protein-coding sequences. The NcDNAlign pipeline combines pairwise BLAST alignments to create initial MSAs, which are then locally improved and trimmed. The program is optimized for speed and hence is particulary well-suited to pilot studies. We demonstrate the practical use of NcDNAlign in three case studies: the search for ncRNAs in gammaproteobacteria and the analysis of conserved noncoding DNA in nematodes and teleost fish, in the latter case focusing on the fate of duplicated ultra-conserved regions. Compared to the currently widely used genome-wide alignment program TBA, our program results in a 20- to 30-fold reduction of CPU time necessary to generate gammaproteobacterial alignments. A showcase application of bacterial ncRNA prediction based on alignments of both algorithms results in similar sensitivity, false discovery rates, and up to 100 putatively novel ncRNA structures. Similar findings hold for our application of NcDNAlign to the identification of ultra-conserved regions in nematodes and teleosts. Both approaches yield conserved sequences of unknown function, result in novel evolutionary insights into conservation patterns among these genomes, and manifest the benefits of an efficient and reliable genome-wide alignment package. The software is available under the GNU Public License at http://www.bioinf.uni-leipzig.de/Software/NcDNAlign/.