RESUMEN
The C. elegans eat-3 gene encodes a mitochondrial dynamin family member homologous to Opa1 in humans and Mgm1 in yeast. We find that mutations in the C. elegans eat-3 locus cause mitochondria to fragment in agreement with the mutant phenotypes observed in yeast and mammalian cells. Electron microscopy shows that the matrices of fragmented mitochondria in eat-3 mutants are divided by inner membrane septae, suggestive of a specific defect in fusion of the mitochondrial inner membrane. In addition, we find that C. elegans eat-3 mutant animals are smaller, grow slower, and have smaller broodsizes than C. elegans mutants with defects in other mitochondrial fission and fusion proteins. Although mammalian Opa1 is antiapoptotic, mutations in the canonical C. elegans cell death genes ced-3 and ced-4 do not suppress the slow growth and small broodsize phenotypes of eat-3 mutants. Instead, the phenotypes of eat-3 mutants are consistent with defects in oxidative phosphorylation. Moreover, eat-3 mutants are hypersensitive to paraquat, which promotes damage by free radicals, and they are sensitive to loss of the mitochondrial superoxide dismutase sod-2. We conclude that free radicals contribute to the pathology of C. elegans eat-3 mutants.
Asunto(s)
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Secuencia de Aminoácidos , Animales , Caenorhabditis elegans/efectos de los fármacos , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Resistencia a Medicamentos/genética , Dinaminas/química , Dinaminas/genética , Dinaminas/metabolismo , Radicales Libres/metabolismo , Radicales Libres/toxicidad , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Proteínas de Unión al GTP/genética , Genes de Helminto , Humanos , Mitocondrias/metabolismo , Mitocondrias/ultraestructura , Proteínas Mitocondriales/genética , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Atrofia Óptica Autosómica Dominante/etiología , Atrofia Óptica Autosómica Dominante/genética , Atrofia Óptica Autosómica Dominante/metabolismo , Fosforilación Oxidativa , Paraquat/toxicidad , Fenotipo , Interferencia de ARN , Proteínas de Saccharomyces cerevisiae/genética , Homología de Secuencia de Aminoácido , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismoRESUMEN
During vertebrate central nervous system development, the apical neuroepithelium is bathed with embryonic Cerebrospinal Fluid (e-CSF) which plays regulatory roles in cortical cell proliferation and maintenance. Here, we report the first proteomic analysis of human e-CSF and compare it to an extensive proteomic analysis of rat e-CSF. As expected, we identified a large collection of protease inhibitors, extracellular matrix proteins, and transport proteins in CSF. However, we also found a surprising suite of signaling and intracellular proteins not predicted by previous proteomic analysis. Some of the intracellular proteins are likely to represent the contents of microvesicles recently described within the CSF (Marzesco, A. M., et al. J. Cell Sci. 2005, 118 (Pt. 13), 2849-2858). Defining the rich composition of e-CSF will enable a greater understanding of its concerted actions during critical stages of brain development.