Resistance to inhibitors of cholinesterase (Ric)-8A and Gαi contribute to cytokinesis abscission by controlling vacuolar protein-sorting (Vps)34 activity

PLoS One. 2014 Jan 21;9(1):e86680. doi: 10.1371/journal.pone.0086680. eCollection 2014.

Abstract

Resistance to inhibitors of cholinesterase (Ric)-8A is a guanine nucleotide exchange factor for Gαi, Gαq, and Gα12/13, which is implicated in cell signaling and as a molecular chaperone required for the initial association of nascent Gα subunits with cellular membranes. Ric-8A, Gαi subunits, and their regulators are localized at the midbody prior to abscission and linked to the final stages of cell division. Here, we identify a molecular mechanism by which Ric-8A affects cytokinesis and abscission by controlling Vps34 activity. We showed that Ric-8A protein expression is post-transcriptionally controlled during the cell cycle reaching its maximum levels at mitosis. A FRET biosensor created to measure conformational changes in Ric-8A by FLIM (Fluorescence Lifetime Imaging Microscopy) revealed that Ric-8A was in a close-state during mitosis and particularly so at cytokinesis. Lowering Ric-8A expression delayed the abscission time of dividing cells, which correlated with increased intercellular bridge length and multinucleation. During cytokinesis, Ric-8A co-localized with Vps34 at the midbody along with Gαi and LGN, where these proteins functioned to regulate Vps34 phosphatidylinositol 3-kinase activity.

Publication types

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

MeSH terms

  • Cell Line, Tumor
  • Class III Phosphatidylinositol 3-Kinases / metabolism*
  • Cytokinesis / physiology*
  • Guanine Nucleotide Exchange Factors / metabolism*
  • HeLa Cells
  • Humans
  • Mitosis / physiology
  • Nuclear Proteins / metabolism
  • RNA Processing, Post-Transcriptional / physiology

Substances

  • Guanine Nucleotide Exchange Factors
  • Nuclear Proteins
  • Ric-8A protein, human
  • Class III Phosphatidylinositol 3-Kinases