Imprinted Small Non-coding RNA Genes: Time to Decipher their Physiological Functions
Stéphane Labialle, Patrice Vitali, and Jérôme Cavaillé
from: Non-coding RNAs and Epigenetic Regulation of Gene Expression: Drivers of Natural Selection (Edited by: Kevin V. Morris). Caister Academic Press, U.K. (2012)
Genomic imprinting is a developmentally controlled form of epigenetic regulation that triggers parent-of-origin specific expression of a few mammalian genes. That is, for a given gene, only one of the two parental alleles is transcriptionnally active. Over the last several years, many imprinted small regulatory non-coding RNAs (ncRNAs, including microRNAs and box C/D small nucleolar RNAs) have been described at four evolutionarily distinct imprinted loci: the Snurf-Snrpn/Prader-Willi Syndrome and Dlk1-Dio3 chromosomal domains, and more recently at the C19MC locus and the Sfmbt2 gene. Remarkably, many imprinted ncRNA loci are clustered within large arrays formed by tandemly-repeated genes of related sequences and processed from long non-coding transcripts extending over hundreds of kilobases. Imprinted gene loci therefore give rise to unique opportunities to address both the impact of small and long non-coding RNA genes on the evolution, expression and function of mammalian genomes. In this chapter, we survey our current understanding of the functions of imprinted ncRNAs, with a particular attention to their suspected involvement in the Prader-Willi disease and higher-brain functions, as well as to their hypothetical contribution in the evolution and/or control of genomic imprinting read more ...