The Vac14-interaction network is linked to regulators of the endolysosomal and autophagic pathway

Mol Cell Proteomics. 2014 Jun;13(6):1397-411. doi: 10.1074/mcp.M113.034108. Epub 2014 Feb 27.


The scaffold protein Vac14 acts in a complex with the lipid kinase PIKfyve and its counteracting phosphatase FIG4, regulating the interconversion of phosphatidylinositol-3-phosphate to phosphatidylinositol-3,5-bisphosphate. Dysfunctional Vac14 mutants, a deficiency of one of the Vac14 complex components, or inhibition of PIKfyve enzymatic activity results in the formation of large vacuoles in cells. How these vacuoles are generated and which processes are involved are only poorly understood. Here we show that ectopic overexpression of wild-type Vac14 as well as of the PIKfyve-binding deficient Vac14 L156R mutant causes vacuoles. Vac14-dependent vacuoles and PIKfyve inhibitor-dependent vacuoles resulted in elevated levels of late endosomal, lysosomal, and autophagy-associated proteins. However, only late endosomal marker proteins were bound to the membranes of these enlarged vacuoles. In order to decipher the linkage between the Vac14 complex and regulators of the endolysosomal pathway, a protein affinity approach combined with multidimensional protein identification technology was conducted, and novel molecular links were unraveled. We found and verified the interaction of Rab9 and the Rab7 GAP TBC1D15 with Vac14. The identified Rab-related interaction partners support the theory that the regulation of vesicular transport processes and phosphatidylinositol-modifying enzymes are tightly interconnected.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy / genetics*
  • Endosomes / metabolism*
  • Flavoproteins / metabolism
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Lysosomes / metabolism*
  • Membrane Proteins / biosynthesis*
  • Membrane Proteins / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoric Monoester Hydrolases / metabolism
  • Protein Interaction Maps / genetics
  • Proteomics
  • Signal Transduction
  • rab GTP-Binding Proteins / biosynthesis
  • rab GTP-Binding Proteins / metabolism
  • rab7 GTP-Binding Proteins


  • Flavoproteins
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • VAC14 protein, human
  • rab7 GTP-Binding Proteins
  • rab7 GTP-binding proteins, human
  • PIKFYVE protein, human
  • FIG4 protein, human
  • Phosphoric Monoester Hydrolases
  • RAB9A protein, human
  • rab GTP-Binding Proteins