53 IMPACTS OF USING PROCAINE AS A DNA-DEMETHYLATING AGENT IN IN VITRO CULTURE OF BOVINE CELLS

Abstract

Euchromatin and heterochromatin organisation define the specificity of each cell type. This structure is controlled by epigenetic modifications and the DNA methylation is one of the best known for inducing transcriptional repression. Recently, procaine was uncovered as a DNA-demethylating agent, but there are few reports about its dynamic epigenetic action on somatic cells. Mono-allelic expression of imprinted genes is controlled by DNA methylation and inherited to somatic tissues of a sex-specific manner. The aim was to investigate the effects of using procaine, a DNA-demethylating agent, in in vitro culture of bovine (Bos taurus indicus) fibroblast for 72 h (passage 4). We have evaluated cell viability, chromosome integrity, and DNA methylation patterns. To evaluate cell viability, we have used trypan blue 0.4%. To evaluate chromosome integrity, we have used conventional cytogenetic analysis. To investigate DNA methylation patterns, we have analysed 2 differentially methylated regions (DMR) located into the exon 10 of IGF2 and exon 1 of XIST imprinted genes, using the bisulfite sequencing method (EZ DNA methylation kit, Zymo Research, Orange, CA, USA). After bisulfite treatment and nested-PCR, the amplicons were separated in agarose gel electrophoresis, purified with GenClean III kit (MP Biomedicals, Irvine, CA, USA), cloned in a pGEM-T easy vector system (Promega, Madison, WI), and sequenced. The DNA sequences were analysed using the BiQ Analyzer v. 2.0 (2008) software. The cell viability data were analysed using ANOVA and Tukey or Kruskal-Wallis and Mann-Whitney tests, and the methylation status were analysed using Student’s t-test or Mann-Whitney tests in the Prophet software (BBN Systems and Technologies). Cell culture using 0.1 mM or 0.5 mM of procaine were viable and the number of cells with intact membrane was higher than the control and 2.0 mM of procaine groups (P ≤ 0.05). The total number of cells was lower in the group with 2.0 mM of procaine (P ≤ 0.01). Cytogenetic analysis showed no differences among the groups, with no chromosome abnormalities detected. The methylation pattern was not different for both DMR evaluated among the groups. We have observed that there was a beneficial effect to the cells that have received supplementation with 0.1 mM or 0.5 mM of procaine, because there was an increase in the number of viable cells without chromosomal abnormalities. We cannot ignore that a global DNA demethylation may have occurred, which was not detected in the specific analysed regions. The results obtained here may contribute to improving the efficiency of animal cloning, transgenic animal production, and the knowledge about stem cells.