Regulation of Interferon-.TAU. Gene Expression and the Maternal Recognition of Pregnancy.

Abstract

In order for pregnancy to be established, the maternal system must recognize the presence of a conceptus(es) within the uterus. This physiological phenomenon, which subsequently causes the extension of the corpus luteum (CL) life-span, is known as maternal recognition of pregnancy. In ruminant ungulates, interferon-tau (IFNτ), produced by the conceptus, binds to the receptor located in the maternal endometrium in a paracrine manner. Its binding then affects levels of endometrial oxytocin receptor and estrogen receptor, which reduces pulsatile secretion of a luteolysin, prostaglandin F2α, resulting in the extension of CL function. Production of IFNτ seems to parallel the degree of trophoblast elongation and as the conceptus begins its attachment to the endometrium, IFNτ levels decline rapidly. Involvement of IFNτ in the process of implantation has long been suspected, but a role for IFNτ other than CL extension or transcriptional regulation of IFNτ genes has not been elucidated. In fact, several transcription factors that regulate the expression of IFNτ have been found, but none could explain its unique regulation. Recent findings related to maternal recognition of pregnancy are presented herein and a new insight into the potential regulation of IFNτ is discussed.