Nutraceutical rescue of pathological changes in iPSC-derived neural cell types from a childhood leukodystrophy caused by mutations in aspartate tRNA synthetase (DARS). — ASN Events
  1. Schedule
  2. Session 1: Stem cells and development
  3. Nutraceutical rescue of pathological changes in iPSC-derived neural cell types from a childhood leukodystrophy caused by mutations in aspartate tRNA synthetase (DARS).

Nutraceutical rescue of pathological changes in iPSC-derived neural cell types from a childhood leukodystrophy caused by mutations in aspartate tRNA synthetase (DARS). (#5)

Ruojie He 1 , Carola Endes 1 , Dmitry Ovchinnikov 1 , Jessica Mar 1 , Joseph Powell 2 , Dominique Froehlich 3 , Matthias Klugmann 3 , Gaia Salomons 4 , Nicole Wolf 4 , Marjo van der Knaap 4 , Adeline Vanderver 5 , Ernst Wolvetang 1
  1. Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, Australia
  2. Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD
  3. Translational Neuroscience Facility & Department of Physiology, School of Medical Sciences, UNSW, Sydney, NSW, Australia
  4. VU University Medical Center, VU University, Amsterdam, The Netherlands
  5. Division of Neurology, Children’s Research Institute,, Children’s Hospital of Philadelphia, Philadelphia, Washington DC , USA

Aminoacyl-tRNA synthetases (ARSs) accurately pair cognate tRNAs with their corresponding amino acids and thus ensure the fidelity of protein synthesis. Surprisingly, the majority of ARS mutations manifest as diseases of the nervous system, with disturbances in myelination a common feature. The DARS gene codes for Aspartate-tRNA synthetase (AspRS) and is mutated in patients with Hypomyelination with Brain Stem and Spinal Cord Involvement and Leg Spasticity (HBSL). How AspRS mutations lead to focal hypomyelination and cognitive impairment has remained unclear. Currently no treatment is available for children with HBSL.

Aim:  Elucidate the underlying pathogenic mechanism of HBSL and test novel therapeutic strategies.

Methods: We reprogrammed HBSL fibroblasts from 5 patients that differ in disease severity into foot-print free IPSC, differentiated these into mature cortical neurons, astrocytes and oligodendrocytes. We next investigated ER-stress, apoptosis, protein translation, in vitro myelination capacity, astrocyte activation, and defined their transcriptomes using total and single cell RNAseq.

Results: We show that HBSL-IPSC derived cortical neurons exhibit increased ER-stress, increased apoptosis, a defective ability to translate proteins with Asp-leader sequences, and  gene expression changes consistent with defective neuronal function. We further find HBSL-iPSC derived astrocytes show aberrant activation, whereas HBSL oligodendrocytes exhibit alignment and myelination capacity defects and specific mitochondrial gene expression differences. Importantly, we are able to show that supplementation of cortical neuronal cultures with the nutraceutical L-Ornithine-L-Aspartate (LOLA) rescues the neuronal phenotypes, indicating this may be a therapeutic option for HBSL patients.

Conclusions: Particular mutation combinations in the DARS gene differentially affect each of the three cell types that collectively control CNS myelination, but most profoundly and consistently affect neuronal function. The observation that supplementation with the safe and readily available nutraceutical LOLA can rescue this phenotype supports the urgent need for pre-clinical studies in mice and safety trials in humans. Our data further suggest that analogous approaches for other tRNA deficiencies may be beneficial.