RESUMEN
Immunoglobulin heavy chain (IgH) variable region exons are assembled from V(H), D and J(H) gene segments in developing B lymphocytes. Within the 2.7-megabase mouse Igh locus, V(D)J recombination is regulated to ensure specific and diverse antibody repertoires. Here we report in mice a key Igh V(D)J recombination regulatory region, termed intergenic control region 1 (IGCR1), which lies between the V(H) and D clusters. Functionally, IGCR1 uses CTCF looping/insulator factor-binding elements and, correspondingly, mediates Igh loops containing distant enhancers. IGCR1 promotes normal B-cell development and balances antibody repertoires by inhibiting transcription and rearrangement of D(H)-proximal V(H) gene segments and promoting rearrangement of distal V(H) segments. IGCR1 maintains ordered and lineage-specific V(H)(D)J(H) recombination by suppressing V(H) joining to D segments not joined to J(H) segments, and V(H) to DJ(H) joins in thymocytes, respectively. IGCR1 is also required for feedback regulation and allelic exclusion of proximal V(H)-to-DJ(H) recombination. Our studies elucidate a long-sought Igh V(D)J recombination control region and indicate a new role for the generally expressed CTCF protein.
Asunto(s)
ADN Intergénico/genética , Reordenamiento Génico de Cadena Pesada de Linfocito B/genética , Recombinación Genética/genética , Secuencias Reguladoras de Ácidos Nucleicos/genética , Proteínas Represoras/metabolismo , Exones VDJ/genética , Animales , Linfocitos B/citología , Linfocitos B/metabolismo , Factor de Unión a CCCTC , Linaje de la Célula/genética , Cromosomas de los Mamíferos/genética , Cromosomas de los Mamíferos/metabolismo , Elementos de Facilitación Genéticos/genética , Retroalimentación Fisiológica , Células Germinativas/metabolismo , Cadenas Pesadas de Inmunoglobulina/genética , Región Variable de Inmunoglobulina/genética , Ratones , Mutación/genética , Timo/citología , Transcripción Genética/genéticaRESUMEN
BACKGROUND: A complete genome sequence and the advent of genome editing open up non-traditional model organisms to mechanistic genetic studies. The mosquito Aedes aegypti is an important vector of infectious diseases such as dengue, chikungunya, and yellow fever and has a large and complex genome, which has slowed annotation efforts. We used comprehensive transcriptomic analysis of adult gene expression to improve the genome annotation and to provide a detailed tissue-specific catalogue of neural gene expression at different adult behavioral states. RESULTS: We carried out deep RNA sequencing across all major peripheral male and female sensory tissues, the brain and (female) ovary. Furthermore, we examined gene expression across three important phases of the female reproductive cycle, a remarkable example of behavioral switching in which a female mosquito alternates between obtaining blood-meals from humans and laying eggs. Using genome-guided alignments and de novo transcriptome assembly, our re-annotation includes 572 new putative protein-coding genes and updates to 13.5 and 50.3 % of existing transcripts within coding sequences and untranslated regions, respectively. Using this updated annotation, we detail gene expression in each tissue, identifying large numbers of transcripts regulated by blood-feeding and sexually dimorphic transcripts that may provide clues to the biology of male- and female-specific behaviors, such as mating and blood-feeding, which are areas of intensive study for those interested in vector control. CONCLUSIONS: This neurotranscriptome forms a strong foundation for the study of genes in the mosquito nervous system and investigation of sensory-driven behaviors and their regulation. Furthermore, understanding the molecular genetic basis of mosquito chemosensory behavior has important implications for vector control.
Asunto(s)
Encéfalo/metabolismo , Genoma de los Insectos , Ovario/metabolismo , Transcriptoma/genética , Aedes , Animales , Secuencia de Bases , Encéfalo/crecimiento & desarrollo , Femenino , Perfilación de la Expresión Génica , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Masculino , Anotación de Secuencia Molecular , Ovario/crecimiento & desarrollo , FilogeniaRESUMEN
Profiling studies of mRNA and microRNA, particularly microarray-based studies, have been extensively used to create compendia of genes that are preferentially expressed in the immune system. In some instances, functional studies have been subsequently pursued. Recent efforts such as the Encyclopedia of DNA Elements have demonstrated the benefit of coupling RNA sequencing analysis with information from expressed sequence tags (ESTs) for transcriptomic analysis. However, the full characterization and identification of transcripts that function as modulators of human immune responses remains incomplete. In this study, we demonstrate that an integrated analysis of human ESTs provides a robust platform to identify the immune transcriptome. Beyond recovering a reference set of immune-enriched genes and providing large-scale cross-validation of previous microarray studies, we discovered hundreds of novel genes preferentially expressed in the immune system, including noncoding RNAs. As a result, we have established the Immunogene database, representing an integrated EST road map of gene expression in human immune cells, which can be used to further investigate the function of coding and noncoding genes in the immune system. Using this approach, we have uncovered a unique metabolic gene signature of human macrophages and identified PRDM15 as a novel overexpressed gene in human lymphomas. Thus, we demonstrate the utility of EST profiling as a basis for further deconstruction of physiologic and pathologic immune processes.