Deletion of RBMX RGG/RG motif in Shashi-XLID syndrome leads to aberrant p53 activation and neuronal differentiation defects

Cell Rep. 2021 Jul 13;36(2):109337. doi: 10.1016/j.celrep.2021.109337.

Abstract

RNA-binding proteins play important roles in X-linked intellectual disability (XLID). In this study, we investigate the contribution of the XLID-associated RBMX in neuronal differentiation. We show that RBMX-depleted cells exhibit aberrant activation of the p53 pathway. Moreover, we identify that the RBMX RGG/RG motif is methylated by protein arginine methyltransferase 5 (PRMT5), and this regulates assembly with the SRSF1 splicing factor into higher-order complexes. Depletion of RBMX or disruption of the RBMX/SRSF1 complex in PRMT5-depleted cells reduces SRSF1 binding to the MDM4 precursor (pre-)mRNA, leading to exon 6 exclusion and lower MDM4 protein levels. Transcriptomic analysis of isogenic Shashi-XLID human-induced pluripotent stem cells (hiPSCs) generated using CRISPR-Cas9 reveals a dysregulation of MDM4 splicing and aberrant p53 upregulation. Shashi-XLID neural progenitor cells (NPCs) display differentiation and morphological abnormalities accompanied with excessive apoptosis. Our findings identify RBMX as a regulator of SRSF1 and the p53 pathway, suggesting that the loss of function of the RBMX RGG/RG motif is the cause of Shashi-XLID syndrome.

Keywords: PRMT5; RBMX; RGG/RG motif; SRSF1; XLID; alternative splicing; iPSCs; membraneless organelles; neuronal differentiation; p53.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Alternative Splicing / genetics
  • Amino Acid Motifs
  • Arginine / metabolism
  • Cell Cycle Proteins / genetics
  • Cell Differentiation*
  • Cell Line, Tumor
  • Cell Nucleus / metabolism
  • DNA-Binding Proteins / metabolism
  • HEK293 Cells
  • Heterogeneous-Nuclear Ribonucleoproteins / chemistry*
  • Heterogeneous-Nuclear Ribonucleoproteins / metabolism
  • Humans
  • Induced Pluripotent Stem Cells / metabolism
  • Mental Retardation, X-Linked / pathology*
  • Methylation
  • Neural Stem Cells / metabolism
  • Neurogenesis
  • Neurons / metabolism*
  • Neurons / pathology*
  • Protein Binding
  • Protein Stability
  • Protein-Arginine N-Methyltransferases / metabolism
  • Proto-Oncogene Proteins / genetics
  • RNA / metabolism
  • RNA-Binding Proteins / metabolism
  • Sequence Deletion*
  • Serine-Arginine Splicing Factors / metabolism
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Heterogeneous-Nuclear Ribonucleoproteins
  • KHDRBS1 protein, human
  • MDM4 protein, human
  • Proto-Oncogene Proteins
  • RBMX protein, human
  • RNA-Binding Proteins
  • SRSF1 protein, human
  • Tumor Suppressor Protein p53
  • Serine-Arginine Splicing Factors
  • RNA
  • Arginine
  • PRMT5 protein, human
  • Protein-Arginine N-Methyltransferases

Supplementary concepts

  • Orofaciodigital syndrome, Shashi type