Meeting Abstract

22.3  Tuesday, Jan. 4  Genomic evolution of a novel cell type: the endometrial stromal cell of placental mammals. LYNCH, VJ; WAGNER, GP*; Yale University; Yale University gunter.wagner@yale.edu

The cell is the most basic functional unit of life and the complexity of multicellular organisms can be measured in terms of the number of distinct cell types comprised in the body and life cycle of an organism. Hence the evolution of complex body plans is, in large part, due to the evolution of novel cell types, and the mechanisms that lead to the origin of novel cell types are critical for understanding the origin of complex organisms. We are addressing this question by investigating the evolution the endometrial stromal cell (ESC), a cell type that originated with the evolution of invasive placentation in the stem lineage of eutherian mammals. The transcriptome of pregnant/decidualized endometrial stromal cells from opossum, armadillio, dog and human was sequenced using next generation sequencing technology. The comparison of these transcritpomes shows that over 1,000 genes where recruited to be expressed in these cells in the stem lineage of placental mammals. Among them a considerable fraction related to G-protein coupled receptor signaling pathways. Many of the genes with derived expression in the ESC are known to be critical for decidualization in humans and mice. In addition, two important ligands, known to be important for implantation, IL11 and LIF also have derived expression in ESC. Interestingly the receptors for these ligands are already present in the opossum, suggesting the evolution of an autocrine feedback loop supporting decidualization and a mechanisms of maternal-fetal communication originated during the evolution of pregnancy. These results suggest that a major mode for of the evolution of a novel cell type are changes in the cell signaling system that determines how the cell is interacting with its environment.