Spatial regulation of translation through RNA localization

Abstract

RNA localization is a mechanism to post-transcriptionally regulate gene expression. Eukaryotic organisms ranging from fungi to mammals localize mRNAs to spatially restrict synthesis of specific proteins to distinct regions of the cytoplasm. In this review, we provide a general summary of RNA localization pathways in Saccharomyces cerevisiae, Xenopus, Drosophila and mammalian neurons.

Figure 1.. A general pathway for cytoplasmic RNA localization can be broken into distinct steps

Step 1 – RNA localization substrates (green line) can be identified in the nucleus by RNA-binding proteins (purple ball). Step 2 – the RNA-protein complex is exported from the nucleus to the cytoplasm through the nuclear pore complex. Step 3 – once in the cytoplasm, the RNA can associate with additional proteins (red) that interface the RNA with motor proteins (blue) that transport the RNA along cytoskeletal filaments (gray) to the site of localization. Step 4 – upon reaching the correct destination, translational repression is relieved and the corresponding protein (green ball) is synthesized at the site of action.

Figure 2.. ASH1 mRNA localization in S. cerevisiae

The distribution of ASH1 mRNA is shown in red, and the positions of the nuclei are shown in blue.

Figure 3.. mRNA localization in Drosophila oocytes

A schematic representation of the Drosophila egg chamber (top panel) oskar mRNA is transcribed in the nurse cells, transported into the oocyte and localized at the posterior pole (red). The bottom panel shows oskar mRNA (red) localization as detected by in situ hybridization. DAPI stained DNA is shown in blue.