AUTHOR=Malnou E. Cécile , Umlauf David , Mouysset Maïlys , Cavaillé Jérôme TITLE=Imprinted MicroRNA Gene Clusters in the Evolution, Development, and Functions of Mammalian Placenta JOURNAL=Frontiers in Genetics VOLUME=9 YEAR=2019 URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2018.00706 DOI=10.3389/fgene.2018.00706 ISSN=1664-8021 ABSTRACT=

In mammals, the expression of a subset of microRNA (miRNA) genes is governed by genomic imprinting, an epigenetic mechanism that confers monoallelic expression in a parent-of-origin manner. Three evolutionarily distinct genomic intervals contain the vast majority of imprinted miRNA genes: the rodent-specific, paternally expressed C2MC located in intron 10 of the Sfmbt2 gene, the primate-specific, paternally expressed C19MC positioned at human Chr.19q13.4 and the eutherian-specific, maternally expressed miRNAs embedded within the imprinted Dlk1-Dio3 domains at human 14q32 (also named C14MC in humans). Interestingly, these imprinted miRNA genes form large clusters composed of many related gene copies that are co-expressed with a marked, or even exclusive, localization in the placenta. Here, we summarize our knowledge on the evolutionary, molecular, and physiological relevance of these epigenetically-regulated, recently-evolved miRNAs, by focusing on their roles in placentation and possibly also in pregnancy diseases (e.g., preeclampsia, intrauterine growth restriction, preterm birth).