Negative feedback at kinetochores underlies a responsive spindle checkpoint signal

Nat Cell Biol. 2014 Dec;16(12):1257-64. doi: 10.1038/ncb3065. Epub 2014 Nov 17.

Abstract

Kinetochores are specialized multi-protein complexes that play a crucial role in maintaining genome stability. They bridge attachments between chromosomes and microtubules during mitosis and they activate the spindle assembly checkpoint (SAC) to arrest division until all chromosomes are attached. Kinetochores are able to efficiently integrate these two processes because they can rapidly respond to changes in microtubule occupancy by switching localized SAC signalling ON or OFF. We show that this responsiveness arises because the SAC primes kinetochore phosphatases to induce negative feedback and silence its own signal. Active SAC signalling recruits PP2A-B56 to kinetochores where it antagonizes Aurora B to promote PP1 recruitment. PP1 in turn silences the SAC and delocalizes PP2A-B56. Preventing or bypassing key regulatory steps demonstrates that this spatiotemporal control of phosphatase feedback underlies rapid signal switching at the kinetochore by: allowing the SAC to quickly transition to the ON state in the absence of antagonizing phosphatase activity; and ensuring phosphatases are then primed to rapidly switch the SAC signal OFF when kinetochore kinase activities are diminished by force-producing microtubule attachments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs / genetics
  • Aurora Kinase B / antagonists & inhibitors
  • Cell Cycle Proteins / antagonists & inhibitors
  • Cell Cycle Proteins / genetics
  • Cell Line, Tumor
  • Chromosome Segregation
  • Feedback, Physiological*
  • HeLa Cells
  • Humans
  • Kinetochores / metabolism*
  • M Phase Cell Cycle Checkpoints / genetics*
  • Microtubule-Associated Proteins / biosynthesis
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Microtubules / metabolism
  • Nocodazole / pharmacology
  • Phosphorylation
  • Protein Binding
  • Protein Phosphatase 2 / genetics
  • Protein Phosphatase 2 / metabolism
  • Protein Structure, Tertiary
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / genetics
  • RNA Interference
  • RNA, Small Interfering
  • Signal Transduction
  • Smad2 Protein / genetics
  • Spindle Apparatus / genetics*
  • Tubulin Modulators / pharmacology

Substances

  • Cell Cycle Proteins
  • Knl1 protein, human
  • Microtubule-Associated Proteins
  • RNA, Small Interfering
  • SGO1 protein, human
  • SMAD2 protein, human
  • Smad2 Protein
  • Tubulin Modulators
  • Protein-Tyrosine Kinases
  • AURKB protein, human
  • Aurora Kinase B
  • BUB1 protein, human
  • Protein-Serine-Threonine Kinases
  • TTK protein, human
  • PP2A-B56alpha protein, human
  • Protein Phosphatase 2
  • Nocodazole