Centromere protein A dynamics in human pluripotent stem cell self-renewal, differentiation and DNA damage

Hum Mol Genet. 2010 Oct 15;19(20):3970-82. doi: 10.1093/hmg/ddq312. Epub 2010 Jul 22.

Abstract

Human pluripotent stem cells (hPSCs) hold significant promise for use in regenerative medicine, or as a model to understand human embryo development. However, the basic mechanisms required for proliferation and self-renewal of hPSCs have not been fully uncovered. Proliferation in all eukaryotes is dependent upon highly regulated expression of the histone H3 variant Centromere protein A (CENP-A). In the current study, we demonstrate that hPSCs have a unique messenger ribonucleic acid (mRNA) reserve of CENP-A not found in somatic fibroblasts. Using short hairpin RNA technology to reduce but not ablate CENP-A, we show that CENP-A-depleted hPSCs are still capable of maintaining a functional centromeric mark, whereas fibroblasts are not. However, upon induction of differentiation or DNA damage, hPSCs with depleted CENP-A arrest in G2/M and undergo apoptosis. Analysis of CENP-A dynamics following DNA damage in hPSCs reveals that 60 min after irradiation, CENP-A is found in multiple small nuclear foci that are mutually exclusive to γH2AX as well as CENP-C. Furthermore, following irradiation, hPSCs with depleted CENP-A mount a normal apoptotic response at 6 h; however at 24 h, apoptosis is significantly increased in CENP-A-depleted hPSCs relative to control. Taken together, our results indicate that hPSCs exhibit a unique mechanism for maintaining genomic integrity by possessing the flexibility to reduce the amount of CENP-A required to maintain a functional centromere under self-renewing conditions, and maintaining a reserve of CENP-A mRNA to rebuild the centromere following differentiation or DNA damage.

Publication types

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

MeSH terms

  • Apoptosis
  • Autoantigens / genetics*
  • Autoantigens / metabolism*
  • Blotting, Western
  • Centromere / physiology*
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone / deficiency
  • Chromosomal Proteins, Non-Histone / genetics*
  • Chromosomal Proteins, Non-Histone / metabolism*
  • DNA Damage*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Fibroblasts / cytology
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • G2 Phase / genetics
  • Gene Expression Regulation
  • Histones / metabolism
  • Humans
  • Pluripotent Stem Cells / cytology
  • Pluripotent Stem Cells / metabolism
  • Pluripotent Stem Cells / physiology*
  • Polymerase Chain Reaction
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / genetics

Substances

  • Autoantigens
  • CENPA protein, human
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Histones
  • RNA, Messenger
  • RNA, Small Interfering