The tRNA pseudouridine synthase TruB1 regulates the maturation of let-7 miRNA

EMBO J. 2020 Oct 15;39(20):e104708. doi: 10.15252/embj.2020104708. Epub 2020 Sep 14.


Let-7 is an evolutionary conserved microRNA that mediates post-transcriptional gene silencing to regulate a wide range of biological processes, including development, differentiation, and tumor suppression. Let-7 biogenesis is tightly regulated by several RNA-binding proteins, including Lin28A/B, which represses let-7 maturation. To identify new regulators of let-7, we devised a cell-based functional screen of RNA-binding proteins using a let-7 sensor luciferase reporter and identified the tRNA pseudouridine synthase, TruB1. TruB1 enhanced maturation specifically of let-7 family members. Rather than inducing pseudouridylation of the miRNAs, high-throughput sequencing crosslinking immunoprecipitation (HITS-CLIP) and biochemical analyses revealed direct binding between endogenous TruB1 and the stem-loop structure of pri-let-7, which also binds Lin28A/B. TruB1 selectively enhanced the interaction between pri-let-7 and the microprocessor DGCR8, which mediates miRNA maturation. Finally, TruB1 suppressed cell proliferation, which was mediated in part by let-7. Altogether, we reveal an unexpected function for TruB1 in promoting let-7 maturation.

Keywords: RNA-binding protein; TruB1; let-7; microRNA; pseudouridine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Cell Line, Tumor
  • Cell Proliferation / genetics*
  • Cell Survival
  • Gene Knockdown Techniques
  • Humans
  • Immunoprecipitation
  • Intramolecular Transferases / genetics
  • Intramolecular Transferases / metabolism*
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Protein Binding
  • RNA Processing, Post-Transcriptional / genetics*
  • RNA-Binding Proteins / metabolism*
  • Recombinant Proteins


  • MicroRNAs
  • RNA-Binding Proteins
  • Recombinant Proteins
  • mirnlet7 microRNA, human
  • Intramolecular Transferases
  • pseudouridine synthases

Associated data

  • GEO/GSE143510
  • GEO/GDS4102
  • GEO/GSE3325
  • GEO/GSE64333