Enhancement of histone acetylation by trichostatin A during in vitro fertilization of bovine oocytes affects cell number of the inner cell mass of the resulting blastocysts.
Histone acetylation is one of the major mechanisms of epigenetic reprogramming of gamete genomes after fertilization to establish a totipotent state for normal development. In the present study, the effects of trichostatin A (TSA), an inhibitor of histone deacetylase, during in vitro fertilization (IVF) of bovine oocytes on subsequent embryonic development were investigated. Cumulus-enclosed oocytes obtained from slaughterhouse bovine ovaries were matured in vitro and subjected to IVF in a defined medium supplemented with 0 (control), 5, 50, and 500 nM TSA for 18 h. After IVF, presumptive zygotes were cultured in modified synthetic oviductal fluid (mSOF) medium until 168 h postinsemination (hpi). Some oocytes were immunostained using antibody specific for histone H4-acetylated lysine 5 at 10 hpi. Cleavage, blastocyst development and cell number of inner cell mass (ICM) and trophectoderm (TE) of blastocysts were assessed. TSA treatment enhanced histone acetylation that was prominent in decondensed sperm nuclei. TSA did not affect the postfertilization cleavage, blastocyst rates, and TE cell number. However, it significantly enhanced ICM cell number (p < 0.05). These results indicate that TSA treatment during IVF of bovine oocytes does not affect blastocyst development but alters the cell number of ICM, suggesting that overriding epigenetic modification of the genome during fertilization has a carryover effect on cell proliferation and differentiation in preimplantation embryos. Thus, further environmental quality controls in assisted reproductive technologies are needed in terms of factors which affect chromatin remodelling.
Department of Genetic Engineering, Kinki University, Wakayama, Japan.
Shuntaro
S
Ikeda
Atsuhiro
A
Tatemizo
Daisaku
D
Iwamoto
Shunji
S
Taniguchi
Yoichiro
Y
Hoshino
Tomoko
T
Amano
Kazuya
K
Matsumoto
Yoshihiko
Y
Hosoi
Akira
A
Iritani
Kazuhiro
K
Saeki
D000107:Acetylation / Q000187:drug effects; D000818:Animals; D001755:Blastocyst / Q000187:drug effects* / Q000502:physiology; D002417:Cattle; D047108:Embryonic Development / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D005307:Fertilization in Vitro / Q000187:drug effects*; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000378:metabolism*; D006877:Hydroxamic Acids / Q000494:pharmacology*; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology
D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; C012589:trichostatin A