Post-translational modifications of RNA-binding proteins and their roles in RNA granules

Post-transcriptional processes critically affect eukaryotic gene expression. Cells respond to environmental and intrinsic stresses by arresting global translation and inducing the accumulation of mRNAs into cytoplasmic RNA granules such as stress granules (SGs) and processing bodies (PBs), which are thought to participate in the regulation of translation and degradation of mRNAs. Stresses trigger the formation of SGs and increase PB size and abundance, and the two granules can share specific mRNAs and proteins. The protein content and dynamics of RNA granules have been extensively studied, but the mechanisms of interaction of RNA-binding proteins (RBPs) with binding partners and the signaling pathways that regulate these interactions are poorly understood. Post-translational modification of proteins in RNA granules via phosphorylation, glycosylation and methylation, influences their associations, enzymatic activities and intracellular locations. There is evidence that the post-translational modification of RBPs has a major influence on their binding to mRNA as well as on the assembly of RNA granules. In this review, recent findings concerning the post-translational modification of RBPs and their possible roles in the assembly of RNA granules are discussed.