title: Defective deacetylation of histone 4 K12 in human oocytes is associated with advanced maternal age and chromosome misalignment.
abstract: BACKGROUND
  Chromosome segregation errors during human oocyte meiosis are associated with low fertility in humans and the incidence of these errors increases with advancing maternal age. Studies of mitosis and meiosis suggest that defective remodeling of chromatin plays a causative role in aneuploidy. We analyzed the histone deacetylation pattern during the final stages of human oocyte maturation to investigate whether defective epigenetic regulation of chromatin remodeling in human oocytes is related to maternal age and leads to segregation errors.
  
  
  METHODS
  Human surplus oocytes of different meiotic maturation stages [germinal vesicle (GV), metaphase (M)I and MII] were collected from standard IVF/ICSI treatments. Oocytes were analyzed for acetylation of different lysines of histone 4 (H4K5, H4K8, H4K12 and H4K16) and for α-tubulin.
  
  
  RESULTS
  Human GV oocytes had an intense staining of the chromatin for all four histone 4 lysine acetylations. MI and MII stage oocytes showed either normal deacetylation or various amounts of defective histone deacetylation. Residual H4K12 acetylation was more frequently found in oocytes obtained from older women, with a significant correlation between defective deacetylation and maternal age (r = 0.185, P = 0.007). Eighty-eight percent of the oocytes with residual acetylation had misaligned chromosomes, whereas only 33% of the oocytes that showed correct deacetylated chromatin had misaligned chromosomes (P < 0.001).
  
  
  CONCLUSIONS
  We conclude that defective deacetylation during human female meiosis increases with maternal age and is correlated with misaligned chromosomes. As chromosome misalignment predisposes to segregation errors, our data imply that defective regulation of histone deacetylation could be an important factor in age-related aneuploidy.
authors.affiliation: Department of Obstetrics and Gynaecology, Subdivision of Reproductive Medicine, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors.forename: I M
authors.initials: IM
authors.lastname: van den Berg
authors.forename: C
authors.initials: C
authors.lastname: Eleveld
authors.forename: M
authors.initials: M
authors.lastname: van der Hoeven
authors.forename: E
authors.initials: E
authors.lastname: Birnie
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: R-J
authors.initials: RJ
authors.lastname: Galjaard
authors.forename: J S E
authors.initials: JS
authors.lastname: Laven
authors.forename: J H
authors.initials: JH
authors.lastname: van Doorninck
mesh_terms: D000107:Acetylation; D000328:Adult; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D020090:Chromosome Segregation / Q000235:genetics / Q000502:physiology*; D005260:Female; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008423:Maternal Age; D009865:Oocytes / Q000254:growth & development / Q000378:metabolism*
chemical_list: D006657:Histones