Biology subjects

Yanick, C.

Publications and source records attributed to Yanick, C..

2 recordsLinked to original sources

bioRxiv2025

SynTEF1 restores the functional disease phenotype of SCA27B in an hiPSC-derived neuronal disease model

Spinocerebellar Ataxia 27B (SCA27B), caused by a deep-intronic GAA repeat expansion in the first intron of the FGF14 gene, is one of the most frequent genetic ataxias. Its underlying disease mechanisms remain largely unknown, and disease-modifying therapies targeting upstream processes are lacking. Here we hypothesized that (i) SCA27B is driven by transcriptional repression of FGF14, which encodes a protein regulating ion channels at the axon initial segment (AIS), resulting in reduced Na+ channel availability and neuronal excitability, and that (ii) these defects can be restored by a synthetic elongation transcription factor (Syn-TEF1). We assessed FGF14 mRNA levels by qPCR and neuronal function by whole-cell patch-clamp recordings in iPSC-derived neurons from two SCA27B patients and two healthy controls. Patients carried GAA repeat expansions that were either monoallelic (391/16 repeats) or biallelic (315/290 repeats), exceeding the common pathogenicity threshold of >250 repeats. FGF14 mRNA levels were reduced approximately to 60% and 70% of control levels in monoallelic and biallelic SCA27B neurons, respectively. This was accompanied by impaired excitability, with cumulative action potential (AP) firing reduced to 38% and 45% of control levels in monoallelic and biallelic lines, respectively, and peak Na current density reduced to 46% and 41%, while voltage-dependent gating of Na channels remained unchanged. Treatment with Syn-TEF1 significantly increased FGF14 mRNA expression and restored cumulative AP firing to 83% and 135% of control levels in monoallelic and biallelic neurons, respectively, and Na peak current density to 95% and 138%. These findings strongly suggest that the pathophysiological cascade in SCA27B - from FGF14 repression to impaired Na+ currents and decreased neuronal excitability - can be reversed by an elongation transcription factor. Our results thus provide a rationale for further exploring Syn-TEF1 as a first gene-targeted, disease-modifying therapeutic approach for SCA27B.

neuroscience↗

bioRxiv2023

Sord deficient rats develop a motor-predominant peripheral neuropathy unveiling novel pathophysiological insights

Biallelic SORD mutations cause one of the most frequent forms of recessive hereditary neuropathy, estimated to affect approximately 10,000 patients in North America and Europe alone. Pathogenic SORD loss-of-function changes in the encoded enzyme sorbitol dehydrogenase result in abnormally high sorbitol levels in cells and serum. How sorbitol accumulation leads to peripheral neuropathy remains to be elucidated. A reproducible animal model for SORD neuropathy is essential to illuminate the pathogenesis of SORD deficiency and for preclinical studies of potential therapies. Therefore, we have generated a Sord knockout (KO), Sord-/-, Sprague Dawley rat, to model the human disease and to investigate the pathophysiology underlying SORD deficiency. We have characterized the phenotype in these rats with a battery of behavioral tests as well as biochemical, physiological, and comprehensive histological examinations. Sord-/- rats had remarkably increased levels of sorbitol in serum, cerebral spinal fluid (CSF), and peripheral nerve. Moreover, serum from Sord-/- rats contained significantly increased levels of neurofilament light chain, NfL, an established biomarker for axonal degeneration. Motor performance significantly declined in Sord-/- animals starting at [~]7 months of age. Gait analysis evaluated with video motion tracking confirmed abnormal gait patterns in the hindlimbs. Motor nerve conduction velocities of the tibial nerves were slowed. Light and electron microscopy of the peripheral nervous system revealed degenerating myelinated axons, de- and remyelinated axons, and a likely pathognomonic finding - enlarged "ballooned" myelin sheaths. These findings mainly affected myelinated motor axons; myelinated sensory axons were largely spared. In summary, Sord-/- rats develop a motor-predominant neuropathy that closely resembles the human phenotype. Our studies revealed novel significant aspects of SORD deficiency, and this model will lead to an improved understanding of the pathophysiology and the therapeutic options for SORD neuropathy.

neuroscience↗