Effect of vitrification on promoter CpG island methylation patterns and expression levels of DNA methyltransferase 1o, histone acetyltransferase 1, and deacetylase 1 in metaphase II mouse oocytes.

OBJECTIVE: To investigate the effect of vitrification on Dnmt1o, Hat1, and Hdac1 promoter CpG island methylation patterns and messenger RNA (mRNA) expression levels in mouse metaphase II (MII) oocytes.
DESIGN: In vitro study.
SETTING: Academic institution. ANIMAL(S): Kunming white mice. INTERVENTION(S): After vitrification, surviving mouse MII oocytes subjected to methylation and expression analysis with fresh oocytes used as a control. MAIN OUTCOME MEASURE(S): Expression levels of mRNA as measured by real-time reverse-transcriptase polymerase chain reaction of methylation patterns of the CpG islands in the Dnmt1o, Hat1, and Hdac1 promoters analyzed by bisulfite mutagenesis and sequencing. RESULT(S): The methylation patterns of the promoter CpG islands in Dnmt1o, Hat1, and Hdac1 were not statistically significantly when comparing vitrified oocytes and fresh oocytes. The expression levels of Hat1 and Hdac1 mRNA were not statistically significantly different in comparing in vitrified oocytes and fresh oocytes. The expression of Dnmt1o mRNA was statistically significantly lower in vitrified oocytes compared with fresh oocytes. CONCLUSION(S): Vitrification did not statistically significantly alter the methylation patterns of the promoter CpG islands in Dnmt1o, Hat1, or Hdac1, but did statistically significantly decrease the expression of Dnmt1o mRNA in mouse MII oocytes.