Loss‐of‐function variants in RNA binding motif protein X‐linked induce neuronal defects contributing to amyotrophic lateral sclerosis pathogenesis

Despite being one of the most prevalent RNA modifications, the role of N6-methyladenosine (m6A) in amyotrophic lateral sclerosis (ALS) remains ambiguous. In this investigation, we explore the contribution of genetic defects of m6A-related genes to ALS pathogenesis. We scrutinized the mutation landscape of m6A genes through a comprehensive analysis of whole-exome sequencing cohorts, encompassing 508 ALS patients and 1660 population-matched controls. Our findings reveal a noteworthy enrichment of RNA binding motif protein X-linked (<i>RBMX</i>) variants among ALS patients, with a significant correlation between pathogenic m6A variants and adverse clinical outcomes. Furthermore, <i>Rbmx</i> knockdown in NSC-34 cells overexpressing mutant TDP43^Q331K results in cell death mediated by an augmented p53 response. Similarly, <i>RBMX</i> knockdown in ALS motor neurons derived from induced pluripotent stem cells (iPSCs) manifests morphological defects and activation of the p53 pathway. Transcriptional analysis using publicly available single-cell sequencing data from the primary motor cortex indicates that RBMX-regulated genes selectively influence excitatory neurons and exhibit enrichment in ALS-implicated pathways. Through integrated analyses, our study underscores the emerging roles played by <i>RBMX</i> in ALS, suggesting a potential nexus between the disease and dysregulated m6A-mediated mRNA metabolism.