Intracytoplasmic Re-localization of miRISC Complexes

Abstract

MicroRNAs (miRNAs) are a conserved class of non-coding RNAs of 22 nucleotides that post-transcriptionally regulate gene expression through translational repression and/or mRNA degradation. A great progress has been made regarding miRNA biogenesis and miRNA-mediated gene regulation. Additionally, an ample amount of information exists with respect to the regulation of miRNAs. However, the cytoplasmic localization of miRNAs and its effect on gene regulatory output is still in progress. We provide a current review of the cytoplasmic miRNA localization in metazoans. We then discuss the dynamic changes in the intracytoplasmic localization of miRNAs as a means to regulate their silencing activity. We then conclude our discussion with the potential molecules that could modulate miRNA localization.

Keywords: localization; mRNP; microRNA; polysome; translational repression.

FIGURE 1

Potential intracytoplasmic destinations of miRISCs. Following transcription and processing in the nucleus, some miRISCs are destined for the nucleus (not shown). Cytoplasmically localized miRISCs can be localized in distinct sites such as: (1) rough endoplasmic reticulum; (2) mitochondria; (3) various types of messenger ribonucleoprotein granules such as P bodies and stress granules; (4) golgi; (5) multivesicular bodies; (6) free polysomes and (7) cytoskeleton-bound polysomes. Organelles and complexes are not drawn to scale.