Meeting Abstract

P3.80  Tuesday, Jan. 6  Molecular evolution of MER-39 and consequences on the evolution of menstruation in primates EMERA, D*; WAGNER, G.P.; Yale University; Yale University deena.emera@yale.edu

Menstruation only occurs in species that exhibit spontaneous decidualization of the endometrial stroma: namely, anthropoid primates and some bat species. The adaptive significance of spontaneous decidualization is unknown, although some have suggested that it evolved to protect the uterus from a deeply invasive primate placenta. To understand the causes of spontaneous decidualization in anthropoids, this study investigates the evolution of transcriptional regulation of prolactin, a well-known marker of decidualization. It is hypothesized here that decidual genes like prolactin have become more responsive to luteal phase signals in the primates that menstruate. It was previously reported that human decidual prolactin is regulated by an alternative promoter that occurs in a primate-specific transposable element: MER-39. To investigate the consequences of the MER-39 insertion on prolactin expression, the taxonomic distribution of MER-39 was first investigated by PCR and BLAST searches. Contrary to what was previously reported, MER-39 inserted upstream of prolactin prior to the diversification within Euarchontoglires, as we found the element in rodents and primates. The evolution of transcription factor binding sites (TFBS) within MER-39 was also investigated. A number of changes in potential and experimentally verified TFBS occurred in the stem lineage of the anthropoids, the clade in which menstruation first appears. These TFBS include those for PR, ETS-1, C/EBP, and FOX01, proteins that are present and active in the luteal phase of the menstrual cycle. The impact of MER-39 TFBS evolution on prolactin expression is also investigated by functional tests comparing the kinetics of reporter gene expression driven by anthropoid and non-anthropoid prolactin promoters.