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Global mRNA polarization regulates translation efficiency in the intestinal epithelium

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Science  22 Sep 2017:
Vol. 357, Issue 6357, pp. 1299-1303
DOI: 10.1126/science.aan2399

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Location, location, location

The distribution of RNA in cells is important for efficient translation into proteins. Asymmetric RNA localization is known in several cell types but is poorly understood in gut epithelial cells. Moor et al. found that transcripts in intestinal enterocytes tend to distribute to the cells' apical or basal cell sides (see the Perspective by Gáspár and Ephrussi). mRNA localization does not generally overlap protein localization; instead, ribosomes are apically biased, which allows more efficient translation. On refeeding of fasted mice, gut cell mRNAs encoding ribosomal proteins exhibit a basal-to-apical shift in localization and a boost in translation. Thus, dynamic polarization of mRNA and polarized translation modulate translational efficiency in the intestinal epithelium.

Science, this issue p. 1299; see also p. 1235

Abstract

Asymmetric messenger RNA (mRNA) localization facilitates efficient translation in cells such as neurons and fibroblasts. However, the extent and importance of mRNA polarization in epithelial tissues are unclear. Here, we used single-molecule transcript imaging and subcellular transcriptomics to uncover global apical-basal intracellular polarization of mRNA in the mouse intestinal epithelium. The localization of mRNAs did not generally overlap protein localization. Instead, ribosomes were more abundant on the apical sides, and apical transcripts were consequently more efficiently translated. Refeeding of fasted mice elicited a basal-to-apical shift in polarization of mRNAs encoding ribosomal proteins, which was associated with a specific boost in their translation. This led to increased protein production, required for efficient nutrient absorption. These findings reveal a posttranscriptional regulatory mechanism involving dynamic polarization of mRNA and polarized translation.

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