Project description:We have generated CRISPR edited versions of hESC line MShef11 to produce MFN2 R94Q/+ and MFN2 R94Q/R94Q lines as a model for Charcot Marie Tooth Disease (CMT) 2A. This were differentiated to limb innervating motor neurons, the predominantly affected cell time in CMT2A and RNA was examined to investigate differences in cell lines.
Project description:Charcot-Marie-Tooth (CMT) disease can be caused by mutations in Aminoacyl-tRNA-Synthetases, including G240R mutation in Glycyl-tRNA-Synthetase (GARS). Ribo-seq generates snapshots of translating ribosomes on mRNA and therefore allows analysis of ribosome pausing mRNA. Here we performed Ribo-seq on lysates of HEK293T cells overexpressing GARS, WT or G240R, to dissect mechanism of CMT linked with translation. We found that GARS G240R causes pausing of ribosomes with glycine codons in A-site. The effect is specific for 21 nt ribosome-protected fragments, produced by ribosomes with empty A-sites, suggestive of the deficit of charged Glycyl-tRNA in GARS G240R-CMT.
Project description:GDAP1 is a mitochondrial fission factor and mutations in GDAP1 cause Charcot-Marie-Tooth disease. Gdap1 knockout mice, mimicking genetic alterations of patients suffering from severe CMT forms, develop an age-related, hypomyelinating peripheral neuropathy. We used microarrays to determine changes in the expression profiles in the peripheral nervous system before a phenotype was detectable in the animal model (2 month of age).
Project description:Heterozygous mutations in six tRNA synthetase genes cause Charcot-Marie-Tooth (CMT) peripheral neuropathy. CMT-mutant glycyl- or tyrosyl-tRNA synthetases inhibit global protein synthesis by an unknown mechanism, independent of aminoacylation activity. We report that tRNAGly overexpression rescues protein synthesis and peripheral neuropathy phenotypes in Drosophila and mouse models of CMT caused by glycyl-tRNA synthetase (GlyRS) mutations (CMT2D). Kinetic experiments revealed that CMT-mutant GlyRS bind tRNAGly, but display markedly slow release rates. This tRNAGly sequestration may deplete the cellular tRNAGly pool, leading to insufficient glycyl-tRNAGly supply to the ribosome and translation deficit.
Project description:<p>In Charcot-Marie-Tooth Disease (CMT) or inherited neuropathy research studies, it is the researcher who has selected what they believe to be important markers of impairment in function in patients. For example, it has been inferred that the wearing of ankle-foot-orthosis (AFOs), the use of walking aids such as canes, or the use of wheelchairs, are appropriate markers for “mild”, “moderate” or “severe” disability, respectively. Whether patients agree with this classification is unknown. By understanding what patients classify as mild, moderate and severe disability in CMT, we will know what our treatments need to target, to have a meaningful impact on the patients' functional status. </p> <p><u>Primary objective:</u> The purpose of this study is to compare patient and healthcare provider impressions of what constitutes mild, moderate and severe disability in CMT. Target population: 200 patients who have self-registered at the Inherited Neuropathy Consortium Contact Registry, a web-based contact registry developed and supported by the Data Management and Coordinating Center (DMCC) for the Rare Diseases Clinical Research Consortium (RDCRN), located at the University of South Florida, and 200 health care professionals attending conferences about CMT, such as the 4th International CMT Consortium to be held in Potomac, Maryland, June 29-July 1, 2011 and the MDA Clinic Directors meeting in Las Vegas, NV March 4-7, 2012. </p> <p><u>Methods:</u> A brief, anonymous, 20-item survey, in which we measure what the physician and the patient think are important indicators of disability in CMT, will be distributed by paper to 200 health care professionals, and via an online link to 200 patients self-registered with the RDCRN contact registry. Out of the 200 patients, approximately 25 patients will be requested to take the survey twice in a 2 to 4 week period.</p> <p><u>Analysis:</u> We will measure the agreement between items in the physician and patient groups, and use items with high agreement in a Disability Severity Index. </p>
Project description:Charcot-Marie-Tooth disease (CMT) is a length-dependent peripheral neuropathy. The aminoacyl-tRNA synthetases constitute the largest protein family implicated in CMT. Aminoacyl-tRNA synthetases are predominantly cytoplasmic, but are also present in the nucleus. Here we show that a nuclear function of tyrosyl-tRNA synthetase (TyrRS) is implicated in a Drosophila model of CMT. CMT-causing mutations in TyrRS induce unique conformational changes, which confer capacity for aberrant interactions with transcriptional regulators in the nucleus, leading to transcription factor E2F1 hyperactivation. Using neuronal tissues, we reveal a broad transcriptional regulation network associated with wild-type TyrRS expression, which is disturbed when a CMT-mutant is expressed. Pharmacological inhibition of TyrRS nuclear entry with embelin reduces, whereas genetic nuclear exclusion of mutant TyrRS prevents hallmark phenotypes of CMT in the Drosophila model. These data highlight that this translation factor may contribute to transcriptional regulation in neurons, and suggest a therapeutic target for CMT.