Biology subjects

Marty, I.

Publications and source records attributed to Marty, I..

4 recordsLinked to original sources

bioRxiv2026

CACNA2D4 variants are associated with exertional heat stroke susceptibility

Exertional Heat Stroke (EHS) is a life-threatening disease defined by severe hyperthermia and sudden neurological dysfunction in healthy individuals exposed to intense physical exercise. As is the case with some forms of malignant hyperthermia, mutations in genes involved in skeletal muscle contraction could predispose some patients to EHS. However, the genetic basis of EHS remains poorly documented. Here we identify EHS-associated variants in the CACNA2D4 gene encoding the Cav Ca2+ channel subunit, 2{delta}4, and describe their impact in heterologous expression systems and a knock-in mutant mouse strain heterozygous for the S299R variant (S299R+/-). In transfected cells, each CACNA2D4 variant, including S299R, affected the trafficking and function of 2{delta}4 and its regulation of the Cav1.1 channel. S299R+/-mice showed EHS-like crisis with signs of rhabdomyolysis and an elevation in core body temperature when submitted to an intense exercise protocol. We show that a CACNA2D4 transcript is expressed in mouse skeletal muscle and that the presence of the S299R variant in 2{delta}4 induces a modification in the calcium flux triggered by muscle cell depolarization. Altogether, our data reveal an unexpected connection between CACNA2D4 gene variants and pathophysiological alterations in skeletal muscle Ca2+ signaling that may increase EHS susceptibility.

genetics↗

bioRxiv2024

Functional benefit of CRISPR/Cas9-induced allele deletion for RYR1 dominant mutation

More than 700 pathogenic or probably pathogenic variations have been identified in the RYR1 gene causing various myopathies collectively known as "RYR1-related myopathies". Currently, there is no treatment for these myopathies, and gene therapy stands out as one of the most promising approaches. In the context of a dominant form of Central Core Disease due to a RYR1 mutation, we aimed at showing the functional benefit of inactivating specifically the mutated RYR1 allele by guiding CRISPR/Cas9 cleavages onto frequent single nucleotide polymorphisms (SNPs) segregating on the same chromosome. Whole-genome sequencing was used to pinpoint SNPs localized on the mutant RYR1 allele and identified specific CRISPR/Cas9 guide-RNAs. Lentiviruses encoding these guide-RNAs and the SpCas9 nuclease were used to transduce immortalized patient muscle cells, inducing the specific deletion of the mutant RYR1 allele. The efficiency of the deletion was assessed at both DNA and RNA levels and at the functional level after monitoring calcium release induced by the stimulation of the RyR1-channel. This study provides in-cellulo proof of concept regarding the benefits of mutant RYR1 allele deletion, in the case of a dominant RYR1 mutation, from both a molecular and functional perspective. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/576997v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@484a3borg.highwire.dtl.DTLVardef@1a842org.highwire.dtl.DTLVardef@cda3d5org.highwire.dtl.DTLVardef@befd91_HPS_FORMAT_FIGEXP M_FIG C_FIG eTOC synopsisMutations in the RYR1 gene, encoding a calcium channel required for muscle contraction, cause severe myopathies. In this study, Marty and colleagues demonstrate the functional benefit of suppression of a mutant RYR1 allele using CRISPR/Cas9, in the case of a dominant mutation, leaving the wild type allele alone.

neuroscience↗

bioRxiv2020

In vivo RyR1 reduction in muscle triggers a core-like myopathy

Some mutations in the RYR1 gene lead to congenital myopathies, through reduction in this calcium channel expression level, but the functional whole organism consequences of reduction in RyR1 amount have never been studied. We have developed and characterized a mouse model with inducible muscle specific RYR1 deletion. Recombination in the RYR1 gene resulted in a progressive reduction in the protein amount and was associated with a progressive muscle weakness and atrophy. Calcium fluxes in isolated muscle fibers were accordingly reduced. Alterations in the muscle structure were observed, with fibers atrophy, abnormal mitochondria distribution, membrane remodeling, associated with increase in the expression level of many proteins and inhibition of the autophagy process. This model demonstrates that RyR1 reduction is sufficient to recapitulate most features of Central Core Disease, and accordingly similar alterations were observed in muscle biopsies from Central Core Disease patients, pointing to common pathophysiological mechanisms related to RyR1 reduction.

neuroscience↗

bioRxiv2019

Trisk95 as Novel Skin Mirror for Normal and Diabetic Systemic Glucose Level

Coping with diabetes requires frequent and even today mostly invasive blood glucose-based monitoring. Partly due to this invasive nature and the associated reduced skin wound healing and increased risk of infection, non-invasive glucose monitoring technologies would represent considerable progress. Edited keratinocytes may enable such a function.\n\nTo address this hypothesis, we conducted a proteomic screen in the skin by making use of the experimental in vivo mouse model of type I diabetes alongside controls. We identified Trisk 95 as the only protein whose expression is induced in response to high blood glucose. A luciferase reporter assay demonstrated that induction of Trisk 95 expression occurs not only at the protein level but also transcriptionally. This induction was associated with a marked elevation in the Fluo-4 signal, suggesting a role for intracellular calcium changes in the signalling cascade. Strikingly, these changes lead concurrently to fragmentation of the mitochondria. As judged from the knockout findings, both the calcium flux and the mitochondrial phenotype were dependent on Trisk 95 function, since the phenotypes in question were abolished.\n\nThe data demonstrate that the skin represents an organ that reacts robustly and thus mirrors changes in systemic blood glucose levels. The findings are also consistent with a channelling model of Trisk 95 that serves as an insulin-independent but glucose-responsive biomarker taking part in releasing calcium from the cellular stores in the skin. The skin cells may thus provide a novel mean for glucose monitoring when analysing changes in labelled Trisk 95 and calcium. By that, this study is the first proof of the concept of our registered patent (No. PCT FI2016/050917), which proposes the use of cells as biosensors for developing personalized health-monitoring devices.

cell biology↗