536. EXPRESSION AND LOCALISATION OF SIRTUIN 1 (SIRT1) IN CELLS OF THE MURINE OVARY

Sirtuin proteins regulate cellular metabolism, survival and function via their deacetylase activity on target histones and proteins. SIRT1 is important in translating the beneficial effects of calorie restriction and in increasing longevity in lower organisms. Many proteins targeted by SIRT1 are important to fertility, including androgen and oestrogen receptors, and transcription factors such as FOXO. We examined the presence of SIRT1 in the ovary, and whether its localisation and expression levels change throughout the reproductive cycle and with female age. 21 day old female C57BL/6 mice were treated with gonadotrophins and ovaries collected from four mice each at 0h (unstimulated), 44h post-PMSG, 8h post-hCG, 11.5h post-hCG and 14h post-hCG. One ovary was fixed for immunohistochemistry, and from the other ovary, cumulus (CC) and granulosa (GC) cells were isolated for real-time RTPCR analysis. To examine the effect of maternal age, 21 day old (young) and 38 week old (old) female Swiss mice were stimulated and ovaries collected 16h later for immunohistochemistry. SIRT1 mRNA and protein was detected in GC and CC at all stages examined; expression was higher in GC compared to CC, and no difference was detected within cell type at different stages of follicle growth. Localisation of SIRT1 protein within the cell, and staining intensity, changed during antrum formation; there were more intensely stained GC towards the antrum, and staining was concentrated around the nucleus. Weak positive staining was detected in mural GC however, in CC, GC on the apical side of the follicle and cells of the ovarian surface epithelium strong staining was observed. We did not observe changes in protein localisation or staining intensity as a consequence of maternal age. SIRT1 mRNA and protein is present in cells of the ovary and studies to determine the potential role it plays in these cells is on going.