Single-cell transcriptomics identifies neural fate disruption and glial reprogramming caused by RARS2 deficiency

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Pontocerebellar hypoplasia type 6 (PCH6) is linked to pathogenic variants in RARS2, affecting mitochondrial arginyl-tRNA synthetase.
• The precise mechanisms by which RARS2 deficiency impacts neural lineage development are not fully understood.

Purpose of the Study:

• To investigate the impact of RARS2 deficiency on neural lineage development using a zebrafish model.
• To elucidate the molecular and cellular changes underlying neurodevelopmental deficits in PCH6.

Main Methods:

• Generated RARS2-deficient zebrafish using CRISPR/Cas9.
• Conducted single-cell RNA sequencing (scRNA-seq) at 48 hours postfertilization.
• Utilized immunofluorescence, in situ hybridization, behavioral assays, and ultrastructural analyses.

Main Results:

• RARS2 deficiency led to impaired survival, motor deficits, mitochondrial damage, and disrupted neurogenesis.
• scRNA-seq identified reduced neuronal populations and increased neural progenitor and glial-like cells.
• Downregulation of neurogenic regulators and upregulation of glial/stress markers were observed, alongside altered developmental pathways (e.g., Notch, Wnt) and activated ECM/inflammatory programs.

Conclusions:

• RARS2 deficiency disrupts mitochondrial integrity and reprograms neural lineage development.
• Mechanisms involve suppressed neurogenic transcriptional networks and activated glial/extracellular matrix programs.
• Findings offer insights into PCH6 pathogenesis and suggest potential therapeutic targets.