N6-methyladenosine reader RBMX is essential for motor cortex excitatory neuron survival in amyotrophic lateral sclerosis

Abstract

Abstract Despite being one of the most common RNA modifications, the role of N6-methyladenosine (m6A) in amyotrophic lateral sclerosis (ALS) remains incompletely understood. The present study aims to explore the involvement of RBMX-mediated m6A posttranscriptional regulation in ALS pathophysiology. We examined the cellular effects of downregulating Rbmx in murine motor neuron cell line NSC-34, and the transcriptomic changes in human cell line HEK293T. The single cell sequencing dataset generated from primary motor cortex of ALS and control subjects was further analyzed, with the expression of RBMX-regulated genes compared between patients and controls across different cell types. Finally, the genetic variation landscape of m6A genes were inspected in a whole-exome sequencing (WES) cohort involving 508 ALS patients. We demonstrated that the disturbance of RBMX expression can induce transcriptomic changes selectively affecting excitatory motoneuron survival. The machine learning models identified several RBMX-regulated hub genes including TBKBP1. In addition, we found that the RBMX mutants affected the disease onset age and survival of ALS patients in a sex-dependent manner. Taken together, our integrated analyses highlighted the emerging roles played by RBMX affecting excitatory motor neuron viability in ALS, which may have important implications in understanding ALS pathogenesis.