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The Sumo-targeted ubiquitin ligase RNF4 regulates the localization and function of the HTLV-1 oncoprotein Tax

Kimberly A Fryrear1, Xin Guo, Oliver Kerscher

  • 1Department of Microbiology and Molecular Cell Biology, The Leroy T. Canoles Jr Cancer Research Center, Eastern Virginia Medical School, Norfolk, VA 23508, USA.

Blood
|November 23, 2011
PubMed

Insights

Really Interesting New Gene (RING) Finger Protein 4 (RNF4) targets the HTLV-1 oncoprotein Tax for modification, causing its relocation from the nucleus to the cytoplasm. This RNF4-mediated relocalization impacts Tax

Area of Science:

  • Molecular Biology
  • Virology
  • Cell Biology

Background:

  • Really Interesting New Gene (RING) Finger Protein 4 (RNF4) is a ubiquitin ligase that targets Small Ubiquitin-like Modifier (SUMO)-modified proteins.
  • RNF4's known function involves the ubiquitin-mediated degradation of sumoylated cellular proteins.

Purpose of the Study:

  • To investigate the interaction between RNF4 and the Human T-cell Leukemia Virus Type 1 (HTLV-1) oncoprotein Tax.
  • To elucidate the functional consequences of RNF4 modification on Tax's subcellular localization and activity.

Main Methods:

  • In vivo and in vitro assays to confirm RNF4-Tax interaction.
  • Mapping of the RNF4-binding site on the Tax protein.
  • Overexpression and RNA interference (RNAi) studies to assess RNF4's effect on Tax localization and activity.
  • Analysis of NF-κB and CREB signaling pathways.

Main Results:

  • RNF4 directly binds to and modifies the HTLV-1 Tax oncoprotein.
  • RNF4-mediated modification causes Tax to relocalize from the nucleus to the cytoplasm.
  • This relocalization alters Tax activity, increasing NF-κB signaling and decreasing CREB signaling.
  • RNF4 depletion prevents DNA damage-induced Tax translocation.

Conclusions:

  • RNF4 acts as a regulator of viral oncoprotein localization and function.
  • RNF4-mediated SUMO-targeted ubiquitin ligase (STUbL) pathways are crucial for controlling the dynamics of viral oncogenes like Tax.
  • These findings offer new insights into the molecular mechanisms governing viral oncogenesis.

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