The Alazami Syndrome-Associated Protein LARP7 Guides U6 Small Nuclear RNA Modification and Contributes to Splicing Robustness

Mol Cell. 2020 Mar 5;77(5):1014-1031.e13. doi: 10.1016/j.molcel.2020.01.001. Epub 2020 Feb 3.


The La-related protein 7 (LARP7) forms a complex with the nuclear 7SK RNA to regulate RNA polymerase II transcription. It has been implicated in cancer and the Alazami syndrome, a severe developmental disorder. Here, we report a so far unknown role of this protein in RNA modification. We show that LARP7 physically connects the spliceosomal U6 small nuclear RNA (snRNA) with a distinct subset of box C/D small nucleolar RNAs (snoRNAs) guiding U6 2'-O-methylation. Consistently, these modifications are severely compromised in the absence of LARP7. Although general splicing remains largely unaffected, transcriptome-wide analysis revealed perturbations in alternative splicing in LARP7-depleted cells. Importantly, we identified defects in 2'-O-methylation of the U6 snRNA in Alazami syndrome siblings carrying a LARP7 mutation. Our data identify LARP7 as a bridging factor for snoRNA-guided modification of the U6 snRNA and suggest that alterations in splicing fidelity contribute to the etiology of the Alazami syndrome.

Keywords: 2′-O-methylation; Alazami syndrome; LARP7; RNA binding proteins; U6 snRNA; snRNAs; snoRNAs; splicing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing*
  • Binding Sites
  • Cell Line, Tumor
  • Child
  • Child, Preschool
  • Conserved Sequence
  • Developmental Disabilities / genetics
  • Developmental Disabilities / metabolism*
  • Female
  • Genetic Predisposition to Disease
  • HEK293 Cells
  • Humans
  • Male
  • Methylation
  • Middle Aged
  • Mutation
  • Nucleic Acid Conformation
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • RNA, Small Nuclear / genetics
  • RNA, Small Nuclear / metabolism*
  • Ribonucleoproteins / genetics
  • Ribonucleoproteins / metabolism*
  • Spliceosomes / genetics
  • Spliceosomes / metabolism*


  • Larp7 protein, human
  • RNA, Small Nuclear
  • Ribonucleoproteins
  • U6 small nuclear RNA