Tyrosyl-tRNA synthetase has a noncanonical function in actin bundling

Abstract

Dominant mutations in tyrosyl-tRNA synthetase (YARS1) and six other tRNA ligases cause Charcot-Marie-Tooth peripheral neuropathy (CMT). Loss of aminoacylation is not required for their pathogenicity, suggesting a gain-of-function disease mechanism. By an unbiased genetic screen in Drosophila, we link YARS1 dysfunction to actin cytoskeleton organization. Biochemical studies uncover yet unknown actin-bundling property of YARS1 to be enhanced by a CMT mutation, leading to actin disorganization in the Drosophila nervous system, human SH-SY5Y neuroblastoma cells, and patient-derived fibroblasts. Genetic modulation of F-actin organization improves hallmark electrophysiological and morphological features in neurons of flies expressing CMT-causing YARS1 mutations. Similar beneficial effects are observed in flies expressing a neuropathy-causing glycyl-tRNA synthetase. Hence, in this work, we show that YARS1 is an evolutionary-conserved F-actin organizer which links the actin cytoskeleton to tRNA-synthetase-induced neurodegeneration.

Boosting BDNF in muscle rescues impaired axonal transport in a mouse model of DI-CMTC peripheral neuropathy

“…Mutations in YARS1 enhance the binding partners TRIM28 and HDAC1 [9], as well as F-actin [23]. In this study, TyrRS WT also appears to interact with TrkB at a low level compared with mutant TyrRS, whereas previous data indicate that this is not the case for GlyRS WT [68, 76].…”

“…For phenotyping at 3, 9 and 15 months, H C T was injected under isoflurane-induced anaesthesia into the tibialis anterior on one side of the body and the contralateral gastrocnemius; this enabled transport assessment in peripheral nerves supplying distinct hindlimb muscles of the same mouse. To assess the impact of TyrRS on transport, 25 ng/muscle of recombinant human proteins (TyrRS WT or TyrRS E196K , produced as described previously [23]) were pre-mixed with H C T prior to bilateral administration into the tibialis anterior muscles of wild-type mice. The side of injection (tibialis anterior versus gastrocnemius, and TyrRS WT versus TyrRS E196K ) was alternated between mice to eliminate time-under-anaesthesia and right/left biases.…”

“…Similar to GlyRS, several different CMT mutations in YARS1 result in an alternative stable conformation of TyrRS [10], which enhances its binding affinity for the transcriptional regulators TRIM28 and HDAC1 [9], as well as F-actin [23]. Moreover, a Drosophila model of DI-CMTC, in which mutant YARS1 is overexpressed, displays a similar pattern of neuropathology and mRNA translation impairment in motor and sensory neurons to that caused by mutant GARS1 [47, 81].…”

Non-muscle myosin II regulates presynaptic actin assemblies and neuronal mechanobiology

“…Thus, the presynaptic actin assembly we identified at the NMJ could be a potential target for neurodegeneration-associated cytoskeletal rearrangements. Of note, we recently described an actin cytoskeleton-based component as a pathomechanism in a subtype of peripheral neuropathy (Charcot-Marie-Tooth/CMT), induced by the actin-binding function of tyrosyl- and other aminoacyl-tRNA synthetases 72 . We observed rearrangements of the actin cytoskeleton at NMJs of the CMT Drosophila model, as well as disorganization of stress fibers in CMT patient-derived fibroblasts.…”

An Adapted GeneSwitch Toolkit for Comparable Cellular and Animal Models: A Proof of Concept in Modeling Charcot-Marie-Tooth Neuropathy

“…Five of the mutations are localized in the catalytic domain of the enzyme; however, a defect in aminoacylation activity is not a shared property among them [30,31]. To uncover the pathomechanism underlying YARS1 CMT , we have characterized extensively three YARS1 CMT mutations both in cellulo and in vivo [30,31,[38][39][40]. Taking advantage of the new GeneSwitch toolkit we developed, we set out to create in a standardized manner unified and novel DI-CMTC cellular and fly models, and compared their hallmark characteristics to the previously published ones.…”