Regulation of Myelination in the Central Nervous System by Nuclear Lamin B1 and Non-coding RNAs.

Adult-onset autosomal dominant leukodystrophy (ADLD) is a progressive and fatal hereditary demyelination disorder characterized initially by autonomic dysfunction and loss of myelin in the central nervous system (CNS). Majority of ADLD is caused by a genomic duplication of the nuclear lamin B1 gene (LMNB1) encoding lamin B1 protein, resulting in increased gene dosage in brain tissue. In vitro, excessive lamin B1 at the cellular level reduces transcription of myelin genes, leading to premature arrest of oligodendrocyte differentiation.

MicroRNA-23a promotes myelination in the central nervous system.

Demyelinating disorders including leukodystrophies are devastating conditions that are still in need of better understanding, and both oligodendrocyte differentiation and myelin synthesis pathways are potential avenues for developing treatment. Overexpression of lamin B1 leads to leukodystrophy characterized by demyelination of the central nervous system, and microRNA-23 (miR-23) was found to suppress lamin B1 and enhance oligodendrocyte differentiation in vitro. Here, we demonstrated that miR-23a-overexpressing mice have increased myelin thickness, providing in vivo evidence that miR-23a enhances both oligodendrocyte differentiation and myelin synthesis.

Lamin B1 mediates cell-autonomous neuropathology in a leukodystrophy mouse model.

Adult-onset autosomal-dominant leukodystrophy (ADLD) is a progressive and fatal neurological disorder characterized by early autonomic dysfunction, cognitive impairment, pyramidal tract and cerebellar dysfunction, and white matter loss in the central nervous system. ADLD is caused by duplication of the LMNB1 gene, which results in increased lamin B1 transcripts and protein expression. How duplication of LMNB1 leads to myelin defects is unknown.

Early alterations of autophagy in Huntington disease-like mice.

In a recent study, we reported in vivo evidence of early and sustained alterations of autophagy markers in a novel knock-in mouse model of Huntington disease (HD). The novel model is derived from selective breeding of HdhQ150 knock-in mice to generate mice with ~200 CAG/polyglutamine repeats (HdhQ200). HdhQ200 knockin mice exhibit an accelerated and more robust motor phenotype than the parent line with detectable abnormalities at 50 weeks and substantial impairments at 80 weeks.

Early autophagic response in a novel knock-in model of Huntington disease.

The aggregation of mutant polyglutamine (polyQ) proteins has sparked interest in the role of protein quality-control pathways in Huntington's disease (HD) and related polyQ disorders. Employing a novel knock-in HD mouse model, we provide in vivo evidence of early, sustained alterations of autophagy in response to mutant huntingtin (mhtt). The HdhQ200 knock-in model, derived from the selective breeding of HdhQ150 knock-in mice, manifests an accelerated and more robust phenotype than the parent line.

Mitochondrial calcium uptake capacity as a therapeutic target in the R6/2 mouse model of Huntington's disease.

Huntington's disease (HD) is an incurable autosomal-dominant neurodegenerative disorder initiated by an abnormally expanded polyglutamine domain in the huntingtin protein. It is proposed that abnormal mitochondrial Ca2+ capacity results in an increased susceptibility to mitochondrial permeability transition (MPT) induction that may contribute significantly to HD pathogenesis. The in vivo contribution of these hypothesized defects remains to be elucidated.

In vivo evidence for NMDA receptor-mediated excitotoxicity in a murine genetic model of Huntington disease.

N-methyl-D-aspartate receptor (NMDAR)-mediated excitotoxicity is implicated as a proximate cause of neurodegeneration in Huntington Disease (HD). This hypothesis has not been tested rigorously in vivo. NMDAR-NR2B subunits are a major NR2 subunit expressed by striatal medium spiny neurons that degenerate in HD.

Rodent genetic models of Huntington disease.

Huntington disease (HD) is a dominantly inherited human neurodegenerative disorder characterized by motor deficits, cognitive impairment, and psychiatric symptoms leading to inexorable decline and death. Since the identification of the huntingtin gene and the characteristic expanded CAG repeat/polyglutamine mutation, multiple murine genetic models and one rat genetic model have been generated. These models fall into two general categories: transgenic models with ectopic expression of the characteristic expanded CAG codon mutation, and knock-in models with expression of mutant huntingtin under control of endogenous regulatory elements.

Longitudinal evaluation of the Hdh(CAG)150 knock-in murine model of Huntington's disease.

Several murine genetic models of Huntington's disease (HD) have been developed. Murine genetic models are crucial for identifying mechanisms of neurodegeneration in HD and for preclinical evaluation of possible therapies for HD. Longitudinal analysis of mutant phenotypes is necessary to validate models and to identify appropriate periods for analysis of early events in the pathogenesis of neurodegeneration.