title: Aging alters histone H3 lysine 4 methylation in mouse germinal vesicle stage oocytes.
abstract: Decreasing oocyte competence with maternal aging is a major factor in mammalian infertility. One of the factors contributing to this infertility is changes to chromatin modifications, such as histone acetylation in old MII stage oocytes. Recent studies indicate that changes in histone acetylation at MII arise at the germinal vesicle (GV) stage. We hypothesised that histone methylation could also change in old GV oocytes. To test this hypothesis, we examined mono-, di- and trimethylation of histone H3 lysine 4 (H3K4 me1, me2 and me3, respectively) in young and older oocytes from 6-8- and 42-44-week-old mice, respectively. We found that H3K4 me2 and me3 decreased in older compared with young GV oocytes (100% vs. 81% and 100% vs. 87%, respectively; P<0.05). H3K4 me2 later increased in older MII oocytes (21% vs. 56%; P<0.05). We also examined the expression of genes encoding the H3K4 demethylases lysine (K)-specific demethylase 1A (Kdm1a) and retinol binding protein 2 (Rbp2). Expression of Kdm1a increased at both the mRNA and protein levels in older GV oocytes, but decreased in older MII oocytes (P<0.05), and was negatively correlated with H3K4 me2 levels. Conversely, expression of Rbp2 mRNA and protein decreased in older GV oocytes (P<0.05), and this was not correlated with H3K4 me3 levels. Finally, we showed that inhibition of Kdm1a of older oocytes at the GV stage restored levels of H3K4 me2 at the MII stage to those seen in 'young' oocytes (41% vs. 38%; P>0.05). These results suggest that changes in expression of H3K4 me2 and Kdm1a in older GV oocytes may represent a molecular mechanism underlying human infertility caused by aging.
authors.affiliation: Department of Biology, Jiangsu University, School of Medical Science and Laboratory Medicine, Zhenjiang 212013, P. R. China.
authors.forename: Gen-Bao
authors.initials: GB
authors.lastname: Shao
authors.affiliation: Department of Radiation Oncology, the Affiliated People's Hospital of Jiangsu University, Zhenjiang 212002, P. R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Biology, Jiangsu University, School of Medical Science and Laboratory Medicine, Zhenjiang 212013, P. R. China.
authors.forename: Liu-Ping
authors.initials: LP
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, the Affiliated People's Hospital of Jiangsu University, Zhenjiang 212002, P. R. China.
authors.forename: Chao-Yang
authors.initials: CY
authors.lastname: Wu
authors.affiliation: Department of Biology, Jiangsu University, School of Medical Science and Laboratory Medicine, Zhenjiang 212013, P. R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Physiology, Jiangsu University, Zhenjiang 212013, P. R. China.
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Sang
authors.affiliation: Department of Pediatrics, the Affiliated Hospital of Jiangsu University, Zhenjiang 212001, P. R. China.
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Lu
authors.affiliation: Department of Biology, Jiangsu University, School of Medical Science and Laboratory Medicine, Zhenjiang 212013, P. R. China.
authors.forename: Ai-Hua
authors.initials: AH
authors.lastname: Gong
authors.affiliation: Department of Biology, Jiangsu University, School of Medical Science and Laboratory Medicine, Zhenjiang 212013, P. R. China.
authors.forename: Feng-Yi
authors.initials: FY
authors.lastname: Du
authors.affiliation: Department of Biology, Jiangsu University, School of Medical Science and Laboratory Medicine, Zhenjiang 212013, P. R. China.
authors.forename: Wan-Xin
authors.initials: WX
authors.lastname: Peng
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D019175:DNA Methylation / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D005260:Female; D056466:Histone Demethylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D007150:Immunohistochemistry; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods; D007247:Infertility, Female / Q000209:etiology*; D051379:Mice; D008856:Microscopy, Fluorescence; D009865:Oocytes / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D054840:Retinol-Binding Proteins, Cellular / Q000378:metabolism; D014191:Tranylcypromine
chemical_list: D017931:DNA Primers; D006657:Histones; C518460:Rbp2 protein, mouse; D054840:Retinol-Binding Proteins, Cellular; D014191:Tranylcypromine; D056466:Histone Demethylases; C504076:KDM1a protein, mouse