The tristetraprolin family consists of mRNA destabilizing genes that bind to target mRNA and degrade them. In this context, TIS11 gene family is of primary interest in the spontaneous fetal loss seen in pigs. I hypothesized that the tristetraprolin family regulates these genes in this model. Higher levels of the TIS11 family transcripts in endometrium and trophoblast samples from healthy conceptuses at gd20 were found than in tissues from arresting conceptus attachment sites and significantly higher levels of TIS11 family transcripts were expressed in trophoblast samples associated with arresting conceptuses at gd50 compared to healthy endometrium and trophoblast. TIS11 proteins were expressed and localized at both maternal and fetal sides of maternal-fetal interface. These results provide a basis for understanding some aspects of gene regulation by mRNA destabilizing factors such as tristetraprolin at the maternal-fetal interface and how these factors may play a role in porcine pregnancy and fetal loss. / Department of Biomedical Sciences, NSERC, Ontario Pork, Bioniche Life Sciences Inc.