Stress Granules and P-Bodies: An Insight into mRNA Translational Control and Decay

RNA granules are higher order RNA-protein complexes formed due to protein-protein and protein-RNA interactions. Various cellular cues such as nutritional stress, oxidative stress, heat shock, unfolded proteins trigger assembly of RNA granules. Stress granules (SGs) and mRNA processing bodies (PBs) are two well-characterized, conserved RNA granule types that form the focus of this review. Other studied RNA granule types are P-granules, Neuronal granules, and GW-bodies. RNA granules (also termed as higher order messenger ribonucleoprotein complexes - mRNPs) have been proposed to play a role in post-transcriptional gene regulation specifically mRNA stability, translation repression, and transport. Both SGs and PBs contain translationally repressed mRNAs, however, processing bodies (PBs) also contain mRNAs undergoing degradation. Proteins with low complexity (LC) regions or intrinsically disordered regions (IDRs) play an important role in granule assembly in general. Mutations in RNA granule components leading to impaired assembly and disassembly of granules have been implicated in Neurodegenerative diseases and Cancers. RNA granules play a key role in determining mRNA fate in cytoplasm, hence understanding the granule assembly and disassembly processes in detail will be a major future milestone.