THE ACTIN-BINDING MOESIN PROTEIN IS REQUIRED FOR HEAT SHOCK GENE EXPRESSION IN DROSOPHILA

The cytoskeletal actin-binding ERM (ezrin, radixin and moesin) proteins play essential role in modulating numerous signal transduction events in the cytoplasm by crosslinking actin filaments with plasma membrane proteins. The nuclear localization of ERMs has been also reported and the involvement of the single Drosophila ERM protein in nuclear mRNA export was recently described. However, because the cytoskeletal activity of ERMs is essential in the cell, and the exact mechanism of their nuclear transport is still unknown, the biological significance of the presence of ERM proteins in the nucleus has not been yet determined. Here we present the first attempt to reveal the in vivo relevance of the nuclear localization of the cytoskeletal ERM protein, Drosophila Moesin. With the help of a nuclear export signal (NES) we decreased the amount of Moesin in the nuclei of the animal. As a result, we observed various developmental defects, demonstrating for the first time the importance of ERM function in the cell nucleus. Transcriptome analysis of the mutant flies revealed, that the lack of nuclear Moe function leads to expression change of about 700 genes, among them a group of heat shock genes. This result together with additional findings demonstrates that in Drosophila, the expression of protein chaperons requires the nuclear functions of Moesin. Overall design: RNA seq of ovaries of moe[NES] flies. 3 replicates for each group.