The MRN-CtIP pathway is required for metaphase chromosome alignment

Mol Cell. 2013 Mar 28;49(6):1097-107. doi: 10.1016/j.molcel.2013.01.023. Epub 2013 Feb 21.

Abstract

Faithful duplication of the genome in S phase followed by its accurate segregation in mitosis is essential to maintain genomic integrity. Recent studies have suggested that proteins involved in DNA transactions are also required for whole-chromosome stability. Here we demonstrate that the MRN (Mre11, Rad50, and Nbs1) complex and CtIP are required for accurate chromosome segregation. Depletion of Mre11 or CtIP, antibody-mediated inhibition of Mre11, or small-molecule inhibition of MRN using mirin results in metaphase chromosome alignment defects in Xenopus egg extracts. Similarly, loss of MRN function adversely affects spindle assembly around DNA-coated beads in egg extracts. Inhibition of MRN function in mammalian cells triggers a metaphase delay and disrupts the RCC1-dependent RanGTP gradient. Addition of the Mre11 inhibitor mirin to egg extracts and mammalian cells reduces RCC1 association with mitotic chromosomes. Thus, the MRN-CtIP pathway contributes to Ran-dependent mitotic spindle assembly by modulating RCC1 chromosome association.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Anhydride Hydrolases
  • Animals
  • Carrier Proteins / metabolism*
  • Cell Cycle Proteins / metabolism
  • Cell Cycle Proteins / physiology
  • Cell Extracts
  • Chromosome Segregation*
  • Chromosomes, Human / genetics
  • Chromosomes, Human / metabolism
  • DNA Repair Enzymes / physiology
  • DNA-Binding Proteins / physiology
  • Endodeoxyribonucleases
  • Guanine Nucleotide Exchange Factors / metabolism
  • HeLa Cells
  • Humans
  • MRE11 Homologue Protein
  • Metaphase*
  • Microtubule-Associated Proteins / metabolism
  • Mitosis
  • Multiprotein Complexes / physiology
  • Nuclear Proteins / metabolism*
  • Nuclear Proteins / physiology
  • Protein Binding
  • Single-Cell Analysis
  • Spindle Apparatus / metabolism*
  • Xenopus
  • Xenopus Proteins / physiology
  • ran GTP-Binding Protein / metabolism

Substances

  • Carrier Proteins
  • Cell Cycle Proteins
  • Cell Extracts
  • DNA-Binding Proteins
  • Guanine Nucleotide Exchange Factors
  • MRE11 protein, human
  • Microtubule-Associated Proteins
  • Multiprotein Complexes
  • NBN protein, human
  • Nuclear Proteins
  • RAN protein, human
  • RCC1 protein, human
  • TPX2 protein, human
  • Xenopus Proteins
  • Endodeoxyribonucleases
  • MRE11 Homologue Protein
  • RBBP8 protein, human
  • Acid Anhydride Hydrolases
  • RAD50 protein, human
  • ran GTP-Binding Protein
  • DNA Repair Enzymes