Identification of Wilms' tumor 1-associating protein complex and its role in alternative splicing and the cell cycle

J Biol Chem. 2013 Nov 15;288(46):33292-302. doi: 10.1074/jbc.M113.500397. Epub 2013 Oct 7.


Wilms' tumor 1-associating protein (WTAP) is a putative splicing regulator that is thought to be required for cell cycle progression through the stabilization of cyclin A2 mRNA and mammalian early embryo development. To further understand how WTAP acts in the context of the cellular machinery, we identified its interacting proteins in human umbilical vein endothelial cells and HeLa cells using shotgun proteomics. Here we show that WTAP forms a novel protein complex including Hakai, Virilizer homolog, KIAA0853, RBM15, the arginine/serine-rich domain-containing proteins BCLAF1 and THRAP3, and certain general splicing regulators, most of which have reported roles in post-transcriptional regulation. The depletion of these respective components of the complex resulted in reduced cell proliferation along with G2/M accumulation. Double knockdown of the serine/arginine-rich (SR)-like proteins BCLAF1 and THRAP3 by siRNA resulted in a decrease in the nuclear speckle localization of WTAP, whereas the nuclear speckles were intact. Furthermore, we found that the WTAP complex regulates alternative splicing of the WTAP pre-mRNA by promoting the production of a truncated isoform, leading to a change in WTAP protein expression. Collectively, these findings show that the WTAP complex is a novel component of the RNA processing machinery, implying an important role in both posttranscriptional control and cell cycle regulation.

Keywords: Alternative Splicing; Cell Cycle; Nuclear RNA; Protein Complexes; Proteomics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / physiology*
  • Animals
  • Cell Cycle Proteins
  • Cell Division / physiology*
  • Cyclin A2 / biosynthesis
  • Cyclin A2 / genetics
  • G2 Phase / physiology*
  • HeLa Cells
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Mice
  • Mice, Inbred BALB C
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • RNA Precursors / genetics
  • RNA Precursors / metabolism*
  • RNA Splicing Factors
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • CCNA2 protein, human
  • Cell Cycle Proteins
  • Cyclin A2
  • Multiprotein Complexes
  • Nuclear Proteins
  • RNA Precursors
  • RNA Splicing Factors
  • RNA-Binding Proteins
  • Transcription Factors
  • WTAP protein, human