Caracterização epigenética do gene POU class 5 homeobox 1 (POU5F1/OCT4) em gametas, embriões e linhagens de fibroblastos bovinos

Abstract

One of the main epigenetic mechanisms is DNA methylation, which consists of the addition of a methyl group (CH3) to a CpG site. One of the characteristics of a zygote is cellular pluripotency, from which a single cell must be able to differentiate itself in a complete organism. In this sense, one of the most important genes is POU class 5 homeobox 1 (POU5F1) which encodes a transcription factor called OCT4 (Transcription factor in octamer 4), so also commonly called in the OCT4 gene literature. It is responsible for maintaining cellular pluripotency and studies show that its expression is controlled by DNA methylation. This study aimed to characterize the methylation profile of a region of the OCT4 gene located within a CpG island, covering the 5'UTR region, exon 1 and part of intron 1, in different cell types (gametes, embryos and fibroblasts), in addition to evaluating gene expression in fetal fibroblasts and adult animals, since in cattle, such a broad characterization of the gene in different tissues had not been performed so far. In general, DNA in the region studied in oocytes was hypermethylated in relation to spermatozoa; embryos have hypomethylation in the studied region. While fetal fibroblasts were hypomethylated in relation to adult fibroblasts. Regarding gene expression, there was no difference in the relative amount of mRNA between adult and fetal fibroblasts, considering p < 0.05. The results found show that the higher the cell differentiation, comparing embryos, fetal fibroblasts and adult fibroblasts, the higher the levels of DNA methylation; in gametes, which despite being highly specialized cells, a pattern of OCT4 hypomethylation was found in DNA, indicating its importance for initial embryonic development.