SVIP induces localization of p97/VCP to the plasma and lysosomal membranes and regulates autophagy

PLoS One. 2011;6(8):e24478. doi: 10.1371/journal.pone.0024478. Epub 2011 Aug 31.

Abstract

The small p97/VCP-interacting protein (SVIP) functions as an inhibitor of the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway. Here we show that overexpression of SVIP in HeLa cells leads to localization of p97/VCP at the plasma membrane, intracellular foci and juxtanuclear vacuoles. The p97/VCP-positive vacuolar structures colocalized or associated with LC3 and lamp1, suggesting that SVIP may regulate autophagy. In support of this possibility, knockdown of SVIP diminished, whereas overexpression of SVIP enhanced LC3 lipidation. Surprisingly, knockdown of SVIP reduced the levels of p62 protein at least partially through downregulation of its mRNA, which was accompanied by a decrease in starvation-induced formation of p62 bodies. Overexpression of SVIP, on the other hand, increased the levels of p62 protein and enhanced starvation-activated autophagy as well as promoted sequestration of polyubiquitinated proteins and p62 in autophagosomes. These results suggest that SVIP plays a regulatory role in p97 subcellular localization and is a novel regulator of autophagy.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Adenosine Triphosphatases / metabolism*
  • Animals
  • Autophagy*
  • Brain / cytology
  • Brain / metabolism
  • Carrier Proteins / metabolism*
  • Cell Cycle Proteins / metabolism*
  • Cell Line
  • Cell Membrane / metabolism*
  • Gene Knockdown Techniques
  • Green Fluorescent Proteins
  • Humans
  • Intracellular Membranes / metabolism*
  • Lysosomal Membrane Proteins / metabolism
  • Lysosomes / metabolism*
  • Membrane Proteins
  • Mice
  • Microtubule-Associated Proteins / metabolism
  • Motor Neurons / cytology
  • Motor Neurons / metabolism
  • Nuclear Proteins / metabolism*
  • Phagosomes / metabolism
  • Phosphate-Binding Proteins
  • Protein Transport
  • Recombinant Fusion Proteins / metabolism
  • Sequestosome-1 Protein
  • Spinal Cord / cytology
  • Spinal Cord / metabolism
  • Ubiquitination
  • Vacuoles / metabolism
  • Valosin Containing Protein

Substances

  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins
  • Cell Cycle Proteins
  • Lamp1 protein, mouse
  • Lysosomal Membrane Proteins
  • MAP1LC3A protein, human
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • Nuclear Proteins
  • Phosphate-Binding Proteins
  • Recombinant Fusion Proteins
  • SQSTM1 protein, human
  • SVIP protein, human
  • SVIP protein, mouse
  • Sequestosome-1 Protein
  • Green Fluorescent Proteins
  • Adenosine Triphosphatases
  • VCP protein, human
  • Valosin Containing Protein
  • Vcp protein, mouse