Notch Regulates RNA Translation

Abstract

The asymmetric cell divisions that occur during the development of certain neuronal systems account for the generation of different cell types from a common precursor cell. Such is true during mechanosensory bristle development in Drosophila where the first asymmetric cell division of a sensory organ precursor cell gives rise to a neuronal and nonneuronal precursor cell. Inhibition of Notch signaling by the intracellular protein Numb accounts for generation of the neuronal cell, but it is not clear how Notch signaling regulates formation of the nonneuronal cell. Okabe et al. report that Notch somehow inhibits the activity of Musashi (MSI), an RNA-binding protein. MSI was found to bind to the 3' untranslated region of an mRNA that encodes Tramtrack69 (TTK69), a transcriptional repressor implicated in determining nonneuronal cell fate. MSI association with TTK69 mRNA inhibited translation in a reporter assay. Hence, MSI-mediated repression of TTK69 translation may account for neuronal cell fate.M. Okabe, T. Imai, M. Kurusu, Y. Hiromi, H. Okano, Translational repression determines a neuronal potential in Drosophila asymmetric cell division. Nature 411, 94-98 (2001). [Online Journal]