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Silencing of OSBP-related protein 8 (ORP8) modifies the macrophage transcriptome, nucleoporin p62 distribution, and

Olivier Béaslas1, Terhi Vihervaara, Jiwei Li

  • 1Minerva Foundation Institute for Medical Research, FI-00290 Helsinki, Finland.

Experimental Cell Research
|June 12, 2012
PubMed

Insights

Oxysterol-binding protein homolog 8 (ORP8) regulates macrophage migration by interacting with nucleoporin NUP62. Silencing ORP8 enhances cell migration and microtubule organization, revealing non-lipid roles for ORP8.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Immunology

Background:

  • Oxysterol-binding protein homolog 8 (ORP8) is an endoplasmic reticulum and nuclear envelope-anchored protein highly expressed in macrophages.
  • Its precise functions beyond lipid metabolism remain incompletely understood.

Purpose of the Study:

  • To investigate the novel functions of ORP8 in macrophages, particularly its role in cellular processes beyond lipid transport.
  • To elucidate the molecular mechanisms underlying ORP8's influence on macrophage behavior.

Main Methods:

  • Stable silencing of ORP8 in mouse RAW264.7 macrophages using shRNA lentiviruses.
  • Microarray transcriptome and gene ontology pathway analysis to identify affected cellular pathways.
  • Analysis of nucleoporin NUP62 expression, localization, and interaction with ORP8.
  • Assessment of cell migration capacity and microtubule cytoskeleton organization.

Main Results:

  • ORP8 knockdown significantly altered nuclear pathways and pathways related to centrosome and microtubule organization.
  • ORP8 silencing increased NUP62 expression and altered its subcellular distribution, including intranuclear localization.
  • ORP8-silenced macrophages exhibited enhanced migration and a more prominent microtubule cytoskeleton.
  • ORP8 competed with Exo70 for NUP62 binding, and NUP62 knockdown abrogated the enhanced migration observed in ORP8-silenced cells.

Conclusions:

  • The study identifies novel, non-lipid-related functions for ORP8 in macrophages, including roles in nuclear processes and microtubule organization.
  • ORP8 suppresses macrophage migration by binding to NUP62, highlighting a new regulatory mechanism for cell motility.

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