The role of SIRT1 during in vitro maturation of oocytes

SIRT1 histone deacetylase acts towards many epigenetic and non-epigenetic targets. The involvement of SIRT1 in oocyte maturation is assumed and the importance of ooplasmic SIRT1 pool for further destiny of matured oocyte is strongly suggested. We hypothesized that SIRT1 play role of the signal molecule in mature oocyte through selected epigenetic and non- epigenetic regulation. We observed SIRT1 re-localization in mature oocyte and the association with spindle microtubules. In matured oocyte, SIRT1 shows a spindle-like pattern and spindle- specific SIRT1 action is supported decreasing α-tubulin acetylation. Based on the observation of histone code in immature and matured oocytes, we suggest that SIRT1 is mostly predestined for epigenetic mode of action in germinal vesicle (GV) of immature oocyte. Accordingly, SIRT1- driven trimethylation of histone H3 on lysine K9 in matured oocyte is considered to be an inheritance of GV epigenetic transformation. Taken together, our observations point out the dual spatiotemporal SIRT1 action in oocyte capable to be switched from epigenetic to the non- epigenetic mode of action readily depending on meiosis progress. Keywords: oocyte, SIRT1, histone, developmental competence, tubuline, epigenetic