Regulation of epigenetic processes by non-coding RNAs

Non-coding RNAs (ncRNAs) have emerged as important regulators of a variety of cellular mechanisms, including chromatin organization. Many ncRNAs play an integral role in modifying chromatin structure by recruiting and directing chromatin-modifying protein complexes to target genomic loci. A subset of ncRNAs is also involved in recruiting chromatin-modifying complexes that impart stable epigenetic marks onto the chromatin, which are propagated through cell divisions and/or generations. The placement of these epigenetic marks by ncRNAs leads to changes in chromatin structure and organization, which affects the accessibility of DNA by transcription factors, leading to the activation or repression of the transcription of target DNA loci. Here, we discuss the role of ncRNAs in various epigenetic processes such as the maintenance and formation of pericentric heterochromatin in both S. pombe and mammals, dosage compensation in both Drosophila and mammals, transgenerational epigenetic inheritance in which small interfering RNAs lead to stable gene silencing that is propagated to future generations in C. elegans, and finally, centromere inheritance.