Sci. STKE, 1 May 2001
RNA Localization Localizing the Signal
Simmonds et al. report that the secreted signaling ligand Wingless (encoded by the wg gene in Drosophila) shows apical polarization of the mRNA in Drosophila embryos. Analysis of the distribution of mRNA from a LacZ reporter construct identified two RNA localization elements in the wg 3' untranslated region (UTR). Simmonds and co-workers substituted the 3' UTR of wg to produce transcripts with uniform and basolateral localizations. WG signaling (based on the ability to rescue a wg mutant phenotype and enhance wg expression) was decreased in the fly embryos with uniformly distributed wg transcripts and was substantially impaired in the fly embryos with basolaterally distributed wg transcripts. Wilkie and Davis focus on the molecular mechanism of mRNA transport to the apical surface of Drosophila synctial embryos through analysis of the movement of uniformly, basolaterally, or apically localized endogenously expressed transcripts and injected mRNAs. Basal and uniformly distributed RNAs separate from apical RNAs when coinjected, whereas multiple coinjected apical targeted RNAs can accumulate in the same transport intermediates en route to the apical surface. Apical localization of injected and endogenously expressed transcripts could be disrupted by agents that destabilized microtubules or by treatments that interfered with the minus-end-directed motor dynein or its coactivator dynactin. Thus, apical localization depends on the microtubule cytoskeleton, and the mRNAs are linked and transported along this network through an interaction with the dynein-dynactin complex.
A. J. Simmonds, G. dosSantos, I. Livne-Bar, H. M. Krause, Apical localization of wingless transcripts is required for Wingless signaling. Cell 105, 107-207 (2001). [Online Journal]
G. S. Wilkie, I. Davis, Drosophila wingless and pair-rule transcripts localize apically by dynein-mediated transport of RNA particles. Cell 105, 209-219 (2001). [Online Journal]
Citation: Localizing the Signal. Sci. STKE 2001, tw3 (2001).
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