239. Expression of PAF-R and p53 in the endometrium during entry into and reactivation from diapause in the tammar wallaby
J. C. Fenelon A , G. Shaw A and M. B. Renfree AZoology, University of Melbourne, Parkville, Vic., Australia.
Reproduction, Fertility and Development 20(9) 39-39 https://doi.org/10.1071/SRB08Abs239
Published: 28 August 2008
Abstract
Embryonic diapause is widespread amongst mammals, but is especially common in the kangaroos and wallabies. In the tammar, Macropus eugenii, the sequence of endocrine events leading to embryonic diapause and reactivation are well defined and the blastocyst can remain in diapause for up to 11 months without cell division or apoptosis occurring (Renfree and Shaw 2000). The ovarian hormones exert their effects on the blastocyst by alterations in the endometrial secretions, but the molecular cross-talk between the endometrium and blastocyst is unknown. One possible regulator of diapause is the phospholipid PAF, an embryotrophin that acts as a trophic/survival factor for the early embryo (O'Neill 2005) partly by inactivating the expression of p53, a cell cycle inhibitor, via the PI3-K pathway. PAF is released from the tammar endometrium around the time of reactivation from diapause (Kojima et al. 1993). This study examined the expression of PAF-R and p53 in the tammar endometrium at entry into, and reactivation from, diapause. PAF-R and p53 were highly conserved with orthologueues in human and mouse. PAF-R and p53 expression was assessed by RT–PCR and both genes were expressed in the endometrium at all stages examined. Quantitative PCR (QPCR) studies performed for PAF-R in the endometrium show that levels of PAF-R vary depending on the stage examined and appear to be increasing at entry into diapause and decreasing at exit from diapause. Immunohistochemical (IHC) studies are in progress to determine the cellular location of PAF-R in the endometrium and confirm the QPCR results. QPCR and IHC studies are in progress to determine if there is any change in levels of expression or cellular location of p53 between the stages examined and how this relates to PAF-R availability. These results suggest that the control of diapause in the tammar involves interactions between multiple factors.
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