Emerging Roles of Long Noncoding RNAs in Gene Expression and Intracellular Organization

Abstract

In the postgenomic era, we have learned that large numbers of RNAs that do not code for proteins, the so-called noncoding RNAs (ncRNAs), are transcribed from large portions of the intergenic regions in mammalian genomes. The biological significance of these ncRNAs remains elusive. Although the research is still limited, recent progress has revealed that several ncRNAs play important roles in various steps of gene expression, including epigenetic chromatin regulation, transcription, RNA processing, protein assembly, and transport. Novel ncRNA functions in the organization of intracellular structures have also been reported. Major ncRNA subsets are expressed in a tissue-specific manner and some are induced by external stimuli. The expression of numerous ncRNAs is drastically changed in some types of cancer cells, suggesting that ncRNAs may be involved in disease as well as in physiological events. Thus, understanding ncRNA functions and mechanisms of action will open new opportunities for developing RNA-based technologies for pharmaceutical application.