RESUMEN
Male germ cell (GC) production is a metabolically driven and apoptosis-prone process. Here, we show that the glucose-sensing transcription factor (TF) MAX-Like protein X (MLX) and its binding partner MondoA are both required for male fertility in the mouse, as well as survival of human tumor cells derived from the male germ line. Loss of Mlx results in altered metabolism as well as activation of multiple stress pathways and GC apoptosis in the testes. This is concomitant with dysregulation of the expression of male-specific GC transcripts and proteins. Our genomic and functional analyses identify loci directly bound by MLX involved in these processes, including metabolic targets, obligate components of male-specific GC development, and apoptotic effectors. These in vivo and in vitro studies implicate MLX and other members of the proximal MYC network, such as MNT, in regulation of metabolism and differentiation, as well as in suppression of intrinsic and extrinsic death signaling pathways in both spermatogenesis and male germ cell tumors (MGCTs).
Asunto(s)
Apoptosis , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/metabolismo , Glucosa/metabolismo , Espermatogénesis , Estrés Fisiológico , Animales , Secuencia de Bases , Supervivencia Celular , Exones/genética , Fertilidad , Eliminación de Gen , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Marcación de Gen , Metabolismo de los Lípidos , Masculino , Ratones Noqueados , Modelos Biológicos , Neoplasias de Células Germinales y Embrionarias/patología , Análisis de Componente Principal , ARN/genética , ARN/metabolismo , Proteínas Represoras/metabolismo , Reproducción , Células de Sertoli/metabolismo , Espermatogénesis/genética , Espermatozoides/metabolismo , Neoplasias Testiculares/patología , Testículo/metabolismo , Factores de Transcripción/metabolismo , Transcripción GenéticaRESUMEN
Much progress has been made in the identification of specific human gene variants that contribute to enhanced susceptibility or resistance to viral diseases. Herein we review multiple discoveries made with genome-wide or candidate gene approaches that have revealed significant insights into virus-host interactions. Genetic factors that have been identified include genes encoding virus receptors, receptor-modifying enzymes, and a wide variety of innate and adaptive immunity-related proteins. We discuss a range of pathogenic viruses, including influenza virus, respiratory syncytial virus, human immunodeficiency virus, human T cell leukemia virus, human papilloma virus, hepatitis B and C viruses, herpes simplex virus, norovirus, rotavirus, parvovirus, and Epstein-Barr virus. Understanding the genetic underpinnings that affect infectious disease outcomes should allow tailored treatment and prevention approaches in the future.
Asunto(s)
Inmunidad Adaptativa , Regulación de la Expresión Génica/inmunología , Predisposición Genética a la Enfermedad , Interacciones Huésped-Patógeno/genética , Inmunidad Innata , Virosis/genética , Citocinas/genética , Citocinas/inmunología , Estudio de Asociación del Genoma Completo , Interacciones Huésped-Patógeno/inmunología , Genética Humana , Humanos , Factores Reguladores del Interferón/genética , Factores Reguladores del Interferón/inmunología , Receptores KIR/genética , Receptores KIR/inmunología , Receptores Virales/genética , Receptores Virales/inmunología , Transducción de Señal , Péptidos y Proteínas Asociados a Receptores de Factores de Necrosis Tumoral/genética , Péptidos y Proteínas Asociados a Receptores de Factores de Necrosis Tumoral/inmunología , Virosis/inmunología , Virosis/patología , Virosis/virologíaRESUMEN
Mesodermal cells signal to neighboring epithelial cells to modulate their proliferation in both normal and disease states. We adapted a Caenorhabditis elegans organogenesis model to enable a genome-wide mesodermal-specific RNAi screen and discovered 39 factors in mesodermal cells that suppress the proliferation of adjacent Ras pathway-sensitized epithelial cells. These candidates encode components of protein complexes and signaling pathways that converge on the control of chromatin dynamics, cytoplasmic polyadenylation, and translation. Stromal fibroblast-specific deletion of mouse orthologs of several candidates resulted in the hyper-proliferation of mammary gland epithelium. Furthermore, a 33-gene signature of human orthologs was selectively enriched in the tumor stroma of breast cancer patients, and depletion of these factors from normal human breast fibroblasts increased proliferation of co-cultured breast cancer cells. This cross-species approach identified unanticipated regulatory networks in mesodermal cells with growth-suppressive function, exposing the conserved and selective nature of mesodermal-epithelial communication in development and cancer.
Asunto(s)
Células Epiteliales/citología , Células Epiteliales/metabolismo , Redes Reguladoras de Genes , Proteínas ras/metabolismo , Animales , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Caenorhabditis elegans/citología , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Linaje de la Célula , Proliferación Celular , Femenino , Fibroblastos/metabolismo , Fibroblastos/patología , Perfilación de la Expresión Génica , Genoma , Humanos , Glándulas Mamarias Animales/citología , Mesodermo/metabolismo , Ratones , Mutación/genética , Proteínas Nucleares , Especificidad de Órganos , Fenotipo , Proteínas Quinasas , Proteínas Serina-Treonina Quinasas/metabolismo , Interferencia de ARN , Transducción de Señal/genética , Células del Estroma/citología , Células del Estroma/metabolismo , Proteínas Activadoras de ras GTPasa/metabolismoRESUMEN
ATP-dependent chromatin remodelers control DNA access for transcription, recombination, and other processes. Acf1 (also known as BAZ1A in mammals) is a defining subunit of the conserved ISWI-family chromatin remodelers ACF and CHRAC, first purified over 15 years ago from Drosophila melanogaster embryos. Much is known about biochemical properties of ACF and CHRAC, which move nucleosomes in vitro and in vivo to establish ordered chromatin arrays. Genetic studies in yeast, flies and cultured human cells clearly implicate these complexes in transcriptional repression via control of chromatin structures. RNAi experiments in transformed mammalian cells in culture also implicate ACF and CHRAC in DNA damage checkpoints and double-strand break repair. However, their essential in vivo roles in mammals are unknown. Here, we show that Baz1a-knockout mice are viable and able to repair developmentally programmed DNA double-strand breaks in the immune system and germ line, I-SceI endonuclease-induced breaks in primary fibroblasts via homologous recombination, and DNA damage from mitomycin C exposure in vivo. However, Baz1a deficiency causes male-specific sterility in accord with its high expression in male germ cells, where it displays dynamic, stage-specific patterns of chromosomal localization. Sterility is caused by pronounced defects in sperm development, most likely a consequence of massively perturbed gene expression in spermatocytes and round spermatids in the absence of BAZ1A: the normal spermiogenic transcription program is largely intact but more than 900 other genes are mis-regulated, primarily reflecting inappropriate up-regulation. We propose that large-scale changes in chromatin composition that occur during spermatogenesis create a window of vulnerability to promiscuous transcription changes, with an essential function of ACF and/or CHRAC chromatin remodeling activities being to safeguard against these alterations.
Asunto(s)
Ensamble y Desensamble de Cromatina/genética , Roturas del ADN de Doble Cadena , Espermatogénesis/genética , Factores de Transcripción/genética , Adenosina Trifosfato/metabolismo , Animales , Cromatina/metabolismo , Reparación del ADN/genética , Drosophila/genética , Fibroblastos/citología , Fibroblastos/metabolismo , Regulación del Desarrollo de la Expresión Génica , Humanos , Infertilidad Masculina/genética , Masculino , Ratones , Ratones Noqueados , Nucleosomas/metabolismo , Cultivo Primario de Células , Factores de Transcripción/biosíntesisRESUMEN
Accurate chromosome segregation during meiosis requires that homologous chromosomes pair and become physically connected so that they can orient properly on the meiosis I spindle. These connections are formed by homologous recombination closely integrated with the development of meiosis-specific, higher-order chromosome structures. The yeast Pch2 protein has emerged as an important factor with roles in both recombination and chromosome structure formation, but recent analysis suggested that TRIP13, the mouse Pch2 ortholog, is not required for the same processes. Using distinct Trip13 alleles with moderate and severe impairment of TRIP13 function, we report here that TRIP13 is required for proper synaptonemal complex formation, such that autosomal bivalents in Trip13-deficient meiocytes frequently displayed pericentric synaptic forks and other defects. In males, TRIP13 is required for efficient synapsis of the sex chromosomes and for sex body formation. Furthermore, the numbers of crossovers and chiasmata are reduced in the absence of TRIP13, and their distribution along the chromosomes is altered, suggesting a role for TRIP13 in aspects of crossover formation and/or control. Recombination defects are evident very early in meiotic prophase, soon after DSB formation. These findings provide evidence for evolutionarily conserved functions for TRIP13/Pch2 in both recombination and formation of higher order chromosome structures, and they support the hypothesis that TRIP13/Pch2 participates in coordinating these key aspects of meiotic chromosome behavior.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Proteínas de Ciclo Celular/metabolismo , Cromosomas de los Mamíferos/genética , Meiosis , Ratones/metabolismo , Proteínas Nucleares/metabolismo , Recombinación Genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomycetales/metabolismo , Complejo Sinaptonémico/metabolismo , ATPasas Asociadas con Actividades Celulares Diversas , Adenosina Trifosfatasas/genética , Animales , Proteínas de Ciclo Celular/genética , Línea Celular , Segregación Cromosómica , Cromosomas de los Mamíferos/metabolismo , Intercambio Genético , Evolución Molecular , Femenino , Masculino , Ratones/genética , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Nucleares/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomycetales/citología , Saccharomycetales/genética , Complejo Sinaptonémico/genéticaRESUMEN
Somatic activation of Ras occurs frequently in human cancers, including one-third of lung cancers. Activating Ras mutations also occur in the germline, leading to complex developmental syndromes. The precise mechanism by which Ras activation results in human disease is uncertain. Here we describe the phenotype of a mouse engineered to harbor a germline oncogenic K-rasG12D mutation. This mouse exhibits early embryonic lethality due to a placental trophoblast defect. Reconstitution with a wild-type placenta rescues the early lethality, but mutant embryos still succumb to cardiovascular and hematopoietic defects. In addition, mutant embryos demonstrate a profound defect in lung branching morphogenesis associated with striking up-regulation of the Ras/mitogen-activated protein kinase (MAPK) antagonist Sprouty-2 and abnormal localization of MAPK activity within the lung epithelium. This defect can be significantly suppressed by lentiviral short hairpin RNA (shRNA)-mediated knockdown of Sprouty-2 in vivo. Furthermore, in the context of K-rasG12D-mediated lung tumorigenesis, Sprouty-2 is also up-regulated and functions as a tumor suppressor to limit tumor number and overall tumor burden. These findings indicate that in the lung, Sprouty-2 plays a critical role in the regulation of oncogenic K-ras, and implicate counter-regulatory mechanisms in the pathogenesis of Ras-based disease.