[摘要]：Non-coding RNAs (ncRNAs) that regulate gene expression in cis or in trans are a shared feature of prokaryotic and eukaryotic genomes. In mammals, cis-acting functions are associated with macro ncRNAs, which can be several hundred thousand nucleotides long. Imprinted ncRNAs are well-studied macro ncRNAs that have cis-regulatory effects on multiple flanking genes. Recent advances indicate that they employ different downstream mechanisms to regulate gene expression in embryonic and placental tissues. A better understanding of these downstream mechanisms will help to improve our general understanding of the function of ncRNAs throughout the genome.
