RESUMEN
The cytoplasmic dynein complex is fundamentally important to all eukaryotic cells for transporting a variety of essential cargoes along microtubules within the cell. This complex also plays more specialized roles in neurons. The complex consists of 11 types of protein that interact with each other and with external adaptors, regulators and cargoes. Despite the importance of the cytoplasmic dynein complex, we know comparatively little of the roles of each component protein, and in mammals few mutants exist that allow us to explore the effects of defects in dynein-controlled processes in the context of the whole organism. Here we have taken a genotype-driven approach in mouse (Mus musculus) to analyze the role of one subunit, the dynein light intermediate chain 1 (Dync1li1). We find that, surprisingly, an N235Y point mutation in this protein results in altered neuronal development, as shown from in vivo studies in the developing cortex, and analyses of electrophysiological function. Moreover, mutant mice display increased anxiety, thus linking dynein functions to a behavioral phenotype in mammals for the first time. These results demonstrate the important role that dynein-controlled processes play in the correct development and function of the mammalian nervous system.
Asunto(s)
Conducta Animal/fisiología , Dineínas Citoplasmáticas/genética , Regulación del Desarrollo de la Expresión Génica/genética , Fenotipo , Mutación Puntual/genética , Animales , Animales Recién Nacidos , Asparagina/genética , Recuento de Células/métodos , Células Cultivadas , Corteza Cerebral/citología , Dendritas/genética , Embrión de Mamíferos , Femenino , Fibroblastos/fisiología , Fibroblastos/ultraestructura , Ganglios Espinales/citología , Proteínas Fluorescentes Verdes/genética , Masculino , Aprendizaje por Laberinto/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Actividad Motora/genética , Proteínas del Tejido Nervioso , Conducción Nerviosa/genética , Neuronas/clasificación , Neuronas/citología , Neuronas/fisiología , Transporte de Proteínas/efectos de los fármacos , Transporte de Proteínas/genética , Desempeño Psicomotor , Estadísticas no Paramétricas , Tirosina/genética , Levantamiento de Peso/fisiologíaRESUMEN
Amyotrophic lateral sclerosis (ALS) is a debilitating and fatal late-onset neurodegenerative disease. Familial cases of ALS (FALS) constitute approximately 10% of all ALS cases, and mutant superoxide dismutase 1 (SOD1) is found in 15-20% of FALS. SOD1 mutations confer a toxic gain of unknown function to the protein that specifically targets the motor neurons in the cortex and the spinal cord. We have previously shown that the autosomal dominant Legs at odd angles (Loa) mutation in cytoplasmic dynein heavy chain (Dync1h1) delays disease onset and extends the life span of transgenic mice harboring human mutant SOD1(G93A). In this study we provide evidence that despite the lack of direct interactions between mutant SOD1 and either mutant or wild-type cytoplasmic dynein, the Loa mutation confers significant reductions in the amount of mutant SOD1 protein in the mitochondrial matrix. Moreover, we show that the Loa mutation ameliorates defects in mitochondrial respiration and membrane potential observed in SOD1(G93A) motor neuron mitochondria. These data suggest that the Loa mutation reduces the vulnerability of mitochondria to the toxic effects of mutant SOD1, leading to improved mitochondrial function in SOD1(G93A) motor neurons.