Histone acetylation during the in vitro maturation of bovine oocytes with different levels of competence
2020
Pontelo, Thais Preisser | Rodrigues, Sarah de Andrade Dias | Kawamoto, Taynan Stonoga | Leme, Ligiane de Oliveira | Gomes, A. C. M. M. | Zangeronimo, Márcio Gilberto | Franco, Mauricio Machaim | Dode, Margot Alves Nunes
We aimed to analyse the histone acetylation status and expression profile of genes involved in histone acetylation (histone acetyltransferase 1 (HAT1), lysine acetyltransferase 2A (KAT2A), histone deacetylase 1 (HDAC1), HDAC2 and HDAC3) in bovine oocytes of different competences during in vitro maturation (IVM). Cumulus–oocyte complexes were recovered from two groups of follicles: minor follicles (1.0–3.0 mm in diameter), classified as low competence (LC) and large follicles (6.0–8.0 mm in diameter) classified as high competence (HC). Oocytes were submitted to IVM for 0, 8 and 24 h and stored for analysis. Acetylation status of histone H4 on lysine K5, K6, K12 and K16 was assessed by immunohistochemistry. For gene expression, mRNA levels were determined by real-time quantitative polymerase chain reaction. All oocytes, regardless of their competence, showed a gradual decrease (P < 0.05) in acetylation signals during IVM. From 0 to 8 h of maturation, an increase (P < 0.05) in the relative abundance of HAT1 mRNA was observed only in the HC oocytes. In this group, higher (P < 0.05) mRNA levels of HDAC1 at 8 h of maturation were also observed. In conclusion, in the present study, LC oocytes were shown to have adequate acetylation levels for the resumption and progression of meiosis; however, these oocytes do not have the capacity to synthesise RNA during IVM as the HC oocytes do.
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