Drosophila Brain Tumor is a translational repressor

  1. Junichiro Sonoda and
  2. Robin P. Wharton1
  1. Howard Hughes Medical Institute, Department of Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA

Abstract

The Drosophila brain tumor (brat) gene encodes a member of the conserved NHL family of proteins, which appear to regulate differentiation and growth in a variety of organisms. One of the founding family members, Caenorhabditis elegans LIN-41, is thought to control posttranscriptional gene expression. However, the mechanism by which LIN-41, or any other NHL protein, acts has not been clear. Using a yeast “four-hybrid” interaction assay, we show that Brain Tumor is recruited to hunchback (hb) mRNA through interactions with Nanos and Pumilio, which bind to the RNA to repress its translation. Interaction with the Nanos/Pumilio/RNA complex is mediated by the Brat NHL domain; single amino acid substitutions in this domain compromise quaternary complex assembly in vitro andhb regulation in vivo. Thus, recruitment of Brat is necessary for translational repression and the normal development of posterior embryonic pattern. In addition to regulating abdominal segmentation, previous genetic analysis has shown that Brat, Nanos, and Pumilio govern a variety of developmental processes. We examined the role of Brat in two of these processes—regulation of maternal Cyclin BmRNA in the embryo and regulation of imaginal disc development. The results of these experiments suggest that NHL domain proteins are recruited to various mRNAs by combinatorial protein–protein interactions.

Keywords

Footnotes

  • 1 Corresponding author.

  • E-MAIL rwharton{at}duke.edu; FAX (919) 681-8984.

  • Article and publication are at www.genesdev.org/cgi/doi/10.1101/gad.870801.

    • Received December 4, 2000.
    • Accepted January 25, 2001.
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