RESUMEN
In contrast to humans and other mammals, zebrafish can successfully regenerate and remyelinate central nervous system (CNS) axons following injury. In addition to common myelin proteins found in mammalian myelin, 36K protein is a major component of teleost fish CNS myelin. Although 36K is one of the most abundant proteins in zebrafish brain, its function remains unknown. Here we investigate the function of 36K using translation-blocking Morpholinos. Morphant larvae showed fewer dorsally migrated oligodendrocyte precursor cells as well as upregulation of Notch ligand. A gamma secretase inhibitor, which prevents activation of Notch, could rescue oligodendrocyte precursor cell numbers in 36K morphants, suggesting that 36K regulates initial myelination through inhibition of Notch signaling. Since 36K like other short chain dehydrogenases might act on lipids, we performed thin layer chromatography and mass spectrometry of lipids and found changes in lipid composition in 36K morphant larvae. Altogether, we suggest that during early development 36K regulates membrane lipid composition, thereby altering the amount of transmembrane Notch ligands and the efficiency of intramembrane gamma secretase processing of Notch and thereby influencing oligodendrocyte precursor cell differentiation and further myelination. Further studies on the role of 36K short chain dehydrogenase in oligodendrocyte precursor cell differentiation during remyelination might open up new strategies for remyelination therapies in human patients.
Asunto(s)
Axones/metabolismo , Proteínas de la Mielina/metabolismo , Vaina de Mielina/metabolismo , Oligodendroglía/citología , Animales , Axones/patología , Encéfalo/metabolismo , Células CHO , Diferenciación Celular/fisiología , Cricetulus , Enfermedades Desmielinizantes/metabolismo , Humanos , Neurogénesis/fisiología , Pez CebraAsunto(s)
Canales de Cloruro/genética , Epilepsia Generalizada/genética , Variación Genética , Canales de Cloruro CLC-2 , Dermatoglifia del ADN , Análisis Mutacional de ADN , Electrofisiología , Epilepsia Generalizada/patología , Epilepsia Generalizada/fisiopatología , Salud de la Familia , Femenino , Genes Dominantes , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Heterocigoto , Humanos , Masculino , LinajeRESUMEN
Idiopathic generalized epilepsy (IGE) is an inherited neurological disorder affecting about 0.4% of the world's population. Mutations in ten genes causing distinct forms of idiopathic epilepsy have been identified so far, but the genetic basis of many IGE subtypes is still unknown. Here we report a gene associated with the four most common IGE subtypes: childhood and juvenile absence epilepsy (CAE and JAE), juvenile myoclonic epilepsy (JME), and epilepsy with grand mal seizures on awakening (EGMA; ref. 8). We identified three different heterozygous mutations in the chloride-channel gene CLCN2 in three unrelated families with IGE. These mutations result in (i) a premature stop codon (M200fsX231), (ii) an atypical splicing (del74-117) and (iii) a single amino-acid substitution (G715E). All mutations produce functional alterations that provide distinct explanations for their pathogenic phenotypes. M200fsX231 and del74-117 cause a loss of function of ClC-2 channels and are expected to lower the transmembrane chloride gradient essential for GABAergic inhibition. G715E alters voltage-dependent gating, which may cause membrane depolarization and hyperexcitability.
Asunto(s)
Canales de Cloruro/genética , Epilepsia Generalizada/genética , Mutación , Adolescente , Adulto , Secuencia de Bases , Membrana Celular/metabolismo , Codón de Terminación , Análisis Mutacional de ADN , ADN Complementario/metabolismo , Electrofisiología , Salud de la Familia , Femenino , Heterocigoto , Humanos , Masculino , Microscopía Confocal , Microscopía Fluorescente , Modelos Biológicos , Datos de Secuencia Molecular , Linaje , Plásmidos/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , TransfecciónRESUMEN
Recently, an association between a regulatory polymorphism in the gene encoding the pro-inflammatory cytokine interleukin (IL)-1beta and febrile convulsions (FC) has been reported. In this study we attempted to confirm these findings in a sample consisting of 99 FC patients and 126 ethnically matched controls. Since about 3% of all FC patients experience unprovoked seizures (epilepsy) later during life we furthermore genotyped 43 patients with non-lesional temporal lobe epilepsy who reported a history of FC. In both samples we failed to show an association between the IL-1beta polymorphism and an increased risk for FC. We only found a trend towards an increased frequency and carriage of the putative IL-1beta susceptibility allele two in a sub-sample of 43 FC patients who reported a positive family history for seizures in first and/or second degree relatives. However, these trends did not reach statistical significance.