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Updated: Jun 4, 2025

Visualization of Protein-protein Interaction in Nuclear and Cytoplasmic Fractions by Co-immunoprecipitation and In Situ Proximity Ligation Assay
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Visualization of Protein-protein Interaction in Nuclear and Cytoplasmic Fractions by Co-immunoprecipitation and In Situ Proximity Ligation Assay

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The proximity interactome of PML isoforms I and II under fatty acid stress

Jordan Thompson1, François-Michel Boisvert2, Jayme Salsman3

  • 1Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Canada.

FEBS Letters
|December 20, 2024
PubMed

Insights

Fatty acid stress alters Promyelocytic leukemia (PML) nuclear bodies. Proximity labeling identified COPII transport proteins interacting with PML NBs, revealing disruptions caused by oleate.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Protein Interactions

Background:

  • Promyelocytic leukemia (PML) protein is a key scaffold for PML nuclear bodies (PML NB).
  • PML NBs can reorganize into Lipid-Associated PML Structures (LAPS) under conditions of fatty acid stress.
  • Understanding how cellular components interact with PML NB under stress is crucial for cellular homeostasis.

Purpose of the Study:

  • To investigate the alterations in the PML protein interactome induced by the fatty acid oleate.
  • To identify specific protein partners of PML NB that are affected by fatty acid stress.
  • To elucidate the role of COPII transport proteins in the context of PML NB structure and function.

Main Methods:

  • Utilized proximity-labeling with ascorbate peroxidase (APEX2) fusions to PMLI and PMLII in U2OS cells.
  • Analyzed the resultant interactome to identify protein-protein associations.
  • Employed proximity ligation assay (PLA) to validate specific interactions between COPII proteins and PML NB.

Main Results:

  • The interactome of PMLI/PMLII under oleate stress included nodes of ESCRT and COPII transport proteins.
  • COPII proteins SEC23B, SEC24A, and USO1 showed preferential association with PML NB.
  • Nuclear localization of USO1 was dependent on PML, while SEC23B and SEC24A localization was not directly affected by PML knockout.

Conclusions:

  • Proximity-labeling successfully identified interactions between COPII transport proteins and PML NB.
  • Fatty acid stress, specifically oleate, disrupts these identified COPII-PML NB interactions.
  • These findings highlight a novel role for COPII transport in regulating PML NB integrity under metabolic stress.
Keywords:
APEX2COPIIlipid‐associated PML structuresnuclear lipid dropletpromyelocytic leukemiaproximity‐dependent biotin identification

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