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Cul3 substrate adaptor SPOP targets Nup153 for degradation

Joseph Y Ong1, Mai Abdusamad1, Ivan Ramirez1

  • 1Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095.

Molecular Biology of the Cell
|January 9, 2025
PubMed

Insights

The study identifies Nuclear Pore Protein 153 (Nup153) as a novel substrate of Speckle-type POZ protein (SPOP). SPOP regulates Nup153 levels, impacting cell proliferation and homeostasis.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • Speckle-type POZ protein (SPOP) is a crucial E3 ubiquitin ligase adaptor regulating protein degradation.
  • Dysregulation of SPOP is implicated in cancer progression by affecting cell growth and proliferation.
  • Understanding SPOP substrates is key to deciphering its role in cellular homeostasis.

Purpose of the Study:

  • To identify novel substrates of SPOP.
  • To investigate the functional relationship between SPOP and its newly identified substrate, Nup153.
  • To elucidate the impact of SPOP-Nup153 interaction on cellular processes.

Main Methods:

  • Co-immunoprecipitation to confirm SPOP-Nup153 binding.
  • Immunofluorescence microscopy to assess subcellular localization.
  • RNA interference (RNAi) to deplete SPOP levels.
  • Western blotting to analyze protein stability.

Main Results:

  • Nuclear Pore Protein 153 (Nup153) was identified as a novel SPOP substrate.
  • SPOP and Nup153 interact and colocalize at the nuclear envelope.
  • SPOP mediates Nup153 ubiquitylation and degradation; SPOP depletion stabilizes Nup153.
  • Loss of SPOP enhances nuclear envelope localization of Mad1, a protein tethered by Nup153.

Conclusions:

  • SPOP directly regulates Nup153 protein levels.
  • This regulation impacts nuclear pore complex function and spindle assembly checkpoint.
  • Findings expand the understanding of SPOP's role in protein homeostasis and cell proliferation control.

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