Kim-Ha, J., Kerr, K., and Macdonald, P.M. (1995).
Translational regulation of oskar mRNA by bruno, an ovarian RNA binding protein, is essential.
Cell 81, 403-412.
Abstract
oskar protein directs the deployment of nanos, the posterior body patterning morphogen in Drosophila. To avoid inappropriate activation of nanos, oskar activity must appear only at the posterior pole of the oocyte, where the oskar mRNA becomes localized during oogenesis. Here we show that translation of oskar mRNA is, and must be, repressed prior to its localization; absence of repression allows oskar protein to accumulate throughout the oocyte, specifying posterior body patterning throughout the embryo. Translational repression is mediated by an ovarian protein, bruno, that binds specifically to bruno response elements (BREs), present in multiple copies in the oskar mRNA 3' UTR. Addition of BREs to a heterologous mRNA renders it sensitive to translational repression in the ovary.