The Caspase-Related Protease Separase (Extra Spindle Poles) Regulates Cell Polarity and Cytokinesis in Arabidopsis

Plant Cell. 2013 Jun;25(6):2171-86. doi: 10.1105/tpc.113.113043. Epub 2013 Jun 28.

Abstract

Vesicle trafficking plays an important role in cell division, establishment of cell polarity, and translation of environmental cues to developmental responses. However, the molecular mechanisms regulating vesicle trafficking remain poorly understood. Here, we report that the evolutionarily conserved caspase-related protease separase (extra spindle poles [ESP]) is required for the establishment of cell polarity and cytokinesis in Arabidopsis thaliana. At the cellular level, separase colocalizes with microtubules and RabA2a (for RAS genes from rat brainA2a) GTPase-positive structures. Separase facilitates polar targeting of the auxin efflux carrier PIN-formed2 (PIN2) to the rootward side of the root cortex cells. Plants with the radially swollen4 (rsw4) allele with compromised separase activity, in addition to mitotic failure, display isotropic cell growth, perturbation of auxin gradient formation, slower gravitropic response in roots, and cytokinetic failure. Measurements of the dynamics of vesicle markers on the cell plate revealed an overall reduction of the delivery rates of KNOLLE and RabA2a GTPase in separase-deficient roots. Furthermore, dissociation of the clathrin light chain, a protein that plays major role in the formation of coated vesicles, was slower in rsw4 than in the control. Our results demonstrate that separase is a key regulator of vesicle trafficking, which is indispensable for cytokinesis and the establishment of cell polarity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism
  • Cell Membrane / metabolism
  • Cell Polarity / genetics*
  • Cytokinesis / genetics*
  • Fluorescence Recovery After Photobleaching
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Plant
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Immunoblotting
  • Indoleacetic Acids / metabolism
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism
  • Microtubules / metabolism
  • Plant Roots / genetics
  • Plant Roots / growth & development
  • Plant Roots / metabolism
  • Plants, Genetically Modified
  • Protein Binding
  • Qa-SNARE Proteins / genetics
  • Qa-SNARE Proteins / metabolism
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Separase / genetics*
  • Separase / metabolism
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism

Substances

  • Arabidopsis Proteins
  • Indoleacetic Acids
  • KNOLLE protein, Arabidopsis
  • Membrane Transport Proteins
  • PIN1 protein, Arabidopsis
  • PIN2 protein, Arabidopsis
  • Qa-SNARE Proteins
  • Green Fluorescent Proteins
  • AESP protein, Arabidopsis
  • Separase
  • Rab GTPase 11C, Arabidopsis thaliana
  • rab GTP-Binding Proteins