mRNA on the move: the road to its biological destiny

Abstract

Cells have evolved to regulate the asymmetric distribution of specific mRNA targets to institute spatial and temporal control over gene expression. Over the last few decades, evidence has mounted as to the importance of localization elements in the mRNA sequence and their respective RNA-binding proteins. Live imaging methodologies have shown mechanistic details of this phenomenon. In this minireview, we focus on the advanced biochemical and cell imaging techniques used to tweeze out the finer aspects of mechanisms of mRNA movement.

Keywords: 3′-UTR; Fluorescence; Gene Expression; In Vivo Imaging; Localization Element/Zipcode; RNA Transport; RNA-Protein Interaction; RNA-binding Proteins; mRNA; β-Actin mRNA.

FIGURE 1.

The many roads of mRNA movement. Shown is a simulation of mRNA motility within cells. mRNA tracks represent mRNA movements as a function of time, coded from purple/blue to red. Panel I, fibroblast Cell. a, nuclear mRNAs are subjected to corralled diffusion during much of the tortuous path through the nucleus due to chromatin confinement. b, in motile cells, mRNA is mainly diffusive, although it occasionally travels along the cytoskeleton. mRNAs localized to the leading edge have larger diffusion coefficients on average (c), whereas the movement of perinuclear mRNAs is more confined (d). Panel II, Drosophila oocyte. e, although oskar mRNA is largely diffusive, localization of the mRNA in oocyte stage 9 is accomplished through a slight bias in active transport of mRNA on microtubules toward the posterior pole (P; arrow) (74). A, anterior; D, dorsal; V, ventral. Panel III, neuron. f, neuronal mRNAs depend largely on microtubule-based transport for localization into dendrites. g, Arc mRNAs are seen to be docked beneath dendritic spines, indicating putative domains that maintain mRNAs in specific locations. Panel IV, schematic representation of an mRNA. The cap structure in the 5′-end, the poly(A) tail in the 3′-end, the 5′-UTR, the ORF, the 3′-UTR containing an LE, and the RBPs associated are depicted.