45 EFFECT OF DEACETYLASE INHIBITOR VALPROIC ACID ON BOVINE CULTURED SOMATIC CELLS

Abstract

Normal development depends on a precise sequence of changes in the configuration of chromatin. Epigenetic modifications, such as histone acetylation and methylation and DNA methylation, control the precise tissue-specific gene expressions. Valproic acid (VPA) is an aliphatic acid compound and a deacetylase inhibitor that influences cellular proliferation, differentiation, apoptosis, and migration. Several studies have shown that treatment of fused, cloned embryos with VPA improved embryo development. However, whether the treatment of donor cells with VPA affected cloned embryo development was not clear. In the present study, bovine fibroblast cells were treated with VPA at 0, 0.25, 0.5, 1.0, 2.0, and 4.0 mM concentrations for 24 and 48 h, respectively. The cell growth, cell cycle, diploid composition, and histone modifications were examined. The results showed that (1) when the cells were treated with VPA at and over 2.0 mM concentrations for 24 or 48 h, cell growth was significantly inhibited; (2) VPA treatment resulted in a decrease in cell diploid composition; (3) VPA induced the arrestment of cells at the G0/G1 stages; (4) VPA treatment increased early cell apoptosis; (5) VPA at a 4.0 mM concentration and treatment of cells for 24 h improved H3K9 acetylation; however, treatment of cells with VPA decreased H3K9 methylation in all experimental groups; and (6) when the cells treated with VPA at 0, 0.25, 0.5, 1.0, and 2.0 mM concentrations for 24 h were used as donor cells for NT, the cleavage rates were 83.2, 80.0, 82.1, 80.5, and 65.5%, respectively, and the percentages of blastocyst development were 30.5, 29.6, 29.2, 25.0, and 15.5%, respectively. When the cells were treated with VPA at 4.0 mM concentration, the cleavage (65.5%, 76/116) and blastocyst development (15.5%, 18/116) significantly decreased as compared with the control [83.2% (158/190) and 30.5% (58/190), respectively]. The cell numbers of the blastocysts derived from VPA treatment at 0, 0.25, 0.5, 1.0, and 2.0 mM concentrations were 89.6, 88.6, 87.6, 75.0, and 71.3, respectively, which decreased with the increase in VPA concentration. In conclusion, VPA affected cell growth and histone modifications in a concentration-dependent manner. The VPA-treated cells did not improve the cloned embryo development and even decreased blastocyst when VPA was at a high concentration.

This work was supported by the National Basic Research Program of China (no. 2012CB22306).