The E3 ubiquitin ligase UBR5 regulates centriolar satellite stability and primary cilia

Mol Biol Cell. 2018 Jul 1;29(13):1542-1554. doi: 10.1091/mbc.E17-04-0248. Epub 2018 May 9.

Abstract

Primary cilia are crucial for signal transduction in a variety of pathways, including hedgehog and Wnt. Disruption of primary cilia formation (ciliogenesis) is linked to numerous developmental disorders (known as ciliopathies) and diseases, including cancer. The ubiquitin-proteasome system (UPS) component UBR5 was previously identified as a putative positive regulator of ciliogenesis in a functional genomics screen. UBR5 is an E3 ubiquitin ligase that is frequently deregulated in tumors, but its biological role in cancer is largely uncharacterized, partly due to a lack of understanding of interacting proteins and pathways. We validated the effect of UBR5 depletion on primary cilia formation using a robust model of ciliogenesis, and identified CSPP1, a centrosomal and ciliary protein required for cilia formation, as a UBR5-interacting protein. We show that UBR5 ubiquitylates CSPP1, and that UBR5 is required for cytoplasmic organization of CSPP1-comprising centriolar satellites in centrosomal periphery, suggesting that UBR5-mediated ubiquitylation of CSPP1 or associated centriolar satellite constituents is one underlying requirement for cilia expression. Hence, we have established a key role for UBR5 in ciliogenesis that may have important implications in understanding cancer pathophysiology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biopsy
  • Cell Cycle Proteins / metabolism
  • Cell Line, Tumor
  • Centrioles / metabolism*
  • Cilia / metabolism*
  • HEK293 Cells
  • Humans
  • Microtubule-Associated Proteins / metabolism
  • Neoplasms / metabolism
  • Neoplasms / pathology
  • Polyubiquitin / metabolism
  • Protein Binding
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*
  • Ubiquitination

Substances

  • CSPP1 protein, human
  • Cell Cycle Proteins
  • Microtubule-Associated Proteins
  • Polyubiquitin
  • UBR5 protein, human
  • Ubiquitin-Protein Ligases