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Np9 protein of human endogenous retrovirus K interacts with ligand of numb protein X

Vivienne Armbruester1, Marlies Sauter, Klaus Roemer

  • 1Department of Virology, University of the Saarland Medical School, D-66421 Homburg/Saar, Germany.

Journal of Virology
|September 16, 2004
PubMed

Insights

We discovered Np9, a protein from human endogenous retrovirus K, interacts with LNX. This interaction may influence tumorigenesis via the LNX/Numb/Notch pathway in cancer cells.

Area of Science:

  • Molecular Biology
  • Oncology
  • Virology

Background:

  • Np9 is a novel nuclear protein derived from human endogenous retrovirus K.
  • Np9 transcripts are exclusively found in tumors and transformed cells, suggesting a role in tumorigenesis.

Purpose of the Study:

  • To investigate the potential role of Np9 in tumorigenesis.
  • To identify Np9-interacting proteins and elucidate their functional relationship.

Main Methods:

  • Systematic search for Np9-interacting proteins.
  • Co-immunoprecipitation and domain mapping to confirm protein interactions.
  • Analysis of protein stability and degradation pathways (proteasome).
  • Assessment of subcellular localization changes.

Main Results:

  • The RING-type E3 ubiquitin ligase LNX (ligand of Numb protein X) was identified as an Np9-interacting partner.
  • The interaction between Np9 and LNX involves their N- and C-terminal domains and affects LNX's subcellular localization.
  • Np9, similar to Numb, is unstable and undergoes proteasomal degradation when interacting with LNX.
  • Ectopic Numb expression can stabilize recombinant Np9.

Conclusions:

  • Np9 interacts with LNX, a known regulator of the Notch pathway.
  • The Np9-LNX interaction influences protein stability and subcellular localization, potentially impacting the LNX/Numb/Notch signaling axis.
  • Np9 may contribute to tumorigenesis by modulating the LNX/Numb/Notch pathway.

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