Early endometrial and embryonic transcription of tumour necrosis factor α (TNF) and its receptor TNFR2 in cattle
Abstract
Tumour necrosis factor α (TNF) is expressed in reproductive tissues of several mammals. In cattle, we identified TNF protein present in uterine fluid and expressed in endometrium and blastocysts. Therefore, TNF may be involved in embryo-maternal communication. In this work we have investigated the RNA expression of TNF and its receptor TNFR2 in bovine endometrium and blastocysts. On day 5 after estrus, cows were sham transferred (N=6) or transferred (N=5) with multiple in vitro produced (IVP) embryos (N=50). All cows were slaughtered on day 8. Embryos were flushed and endometrial samples were collected from caruncular and intercaruncular areas in the middle and cranial horn regions. Blastocysts that developed entirely in vitro were also collected. Endometrial samples and blastocysts were subjected to RT-qPCR and values were normalized by GeNorm using three reference genes (SLC30A6, C20RF29, and RPL19 for endometrium, and SDHA, GAPD, YWHAZ for embryos). Data were analyzed using the GLM procedure of SAS Version 9.2 and REGWQ test. Endometrial TNF and TNFR2 mRNA levels were not significantly affected by the presence of embryos. However, expression of TNF and TNFR2 transcripts was higher in IVP blastocysts than in blastocysts developed in the uterine tract (p<0.05). TNF transcript level increased in middle vs. the cranial uterine region (p=0.03). Our results suggest that TNF and TNFR2 mediate early embryo-maternal interactions in cattle.