Imprinted miRNA genes at the C19MC locus

C19MC is the largest human miRNA gene cluster discovered so far, with 46 tandemly-repeated miRNA genes extending over a 100 kb genomic region on human chromosome 19q13.41. We reported that this primate-specific miRNA cluster is expressed exclusively in the placenta, with most, if not all, miRNAs processed from tandemly-repeated introns of a large noncoding pri-miRNA. We demonstrated, for the first time, that C19MC is imprinted with only the paternally-inherited allele being transcriptionally active. We also found that the DGCR8-Drosha (Microprocessor) complex accumulates massively on unspliced pri-miRNAs retained at their transcription site. By combining RNAi depletion, co-immunoprecipitation and cell imaging approaches, we are now dissecting the biogenesis and functions of C19MC miRNAs.