Poster abstracts

Poster number 48 submitted by Nathanael Braun

Translational regulation of nanos mRNA by smaug in thedrosophila embryo

Nathanael P. Braun (MCDB, The Ohio State University), Tammy Herzig (MVIMG, The Ohio State University), Cary D. Gardner-Hencken (Molecular Genetics and Microbiology, Duke University Medical Center), Robin P. Wharton (Molecular Genetics and MVIMG, The Ohio State University)

Abstract:
Maternal nanos mRNA is distributed throughout the early Drosophila embryo, but is translated only at the posterior pole in the specialized cytoplasm containing the germline determinants. In the remainder of the embryo, nanos mRNA is repressed by binding of Smaug to sites in the nanos 3’UTR. The piRNA pathway has also been proposed as contributing to the repression of nanos mRNA. Based on preliminary data, we have discovered that the elimination of piRNA binding sites in the 3’ UTR of nanos mRNA has no effect on its repression. Repression of nanos mRNA by Smaug is thought to be partially mediated by recruitment of the eIF-4E inhibitor Cup via direct interaction with the Smaug RNA-binding domain (RBD). At the posterior pole, Oskar has been proposed to interact directly with the Smaug RBD, thereby evicting Smaug from nanos and de-repressing the mRNA. A Smaug chimera we created in which the native RBD is replaced by bacteriophage MS2 Coat Protein regulates an engineered nanos mRNA derivative essentially normally. Additionally, we created a fusion of Cup and MS2 Coat Protein, finding that this fusion protein also regulates the same engineered nanos mRNA. We conclude that Smaug appears to be the major repressor of unlocalized nanos mRNA and that direct interaction of neither Cup nor Oskar with the Smaug RBD is required for nanos mRNA regulation in vivo.

Keywords: nanos, smaug, translational regulation