Meeting Abstract

P3.22  Saturday, Jan. 5  The origin of a new cell type coincides with miRNA innovation: expression and function of derived miRNAs in the human endometrium. TANZER, Andrea; STADLER, Peter F. ; WAGNER, Gunter P. *; Yale University; University of Leipzig, Germany; Yale University gunter.wagner@yale.edu

MicroRNAs (miRNAs) are an abundant class of small non-coding RNAs (ncRNAs) of about 22nt in length. They control gene expression in higher eukaryotes on the transcriptional as well as post-transcriptional level and thus provide an additional RNA based layer of gene regulation. Studying their evolution showed that innovation of miRNAs is still an ongoing process. In metazoans major expansions of the miRNA repertoire coincided with body plan innovation. We study gene expression during the differentiation of endometrial stromal cells, which are part of the inner layer of the uterus, as model system of a novel cell type specific to placental mammals. We find that miRNA expression changes greatly during the hormone induced cell differentiation process. The set of regulated miRNAs includes ancient miRNAs, like members of the let-7 family, as well as eutherian specific ones, e.g. mir-320. The predicted target genes of those novel miRNAs, however, predate the emergence of eutherian mammals. Our data support the idea that in eukaryotes phenotypic innovations are achieved, in part, by adding new players in the RNA based gene regulatory networks rather than new protein coding genes.