Visualization of the transport and anchoring process of bicoid RNA

Abstract

Abstract

Subcellular localization of mRNA is a widespread mechanism used to limit the synthesis of proteins to distinct regions of cells. Through localization of the transcript, a cell achieves an energetically favorable means to generating cellular asymmetry by limiting the production of a protein to the region of its function. Despite the prevalence of this phenomenon, many key features of RNA localization remain poorly understood, such as how RNAs assemble into complexes competent to localize, and how different protein components of these complexes impart an effect upon the localization process.

In this thesis, we explore the mechanisms that contribute to the transport and anchoring of the RNA bicoid. To better understand the mechanisms that contribute to the localization of this mRNA, we first generated an vivo RNA labeling system to allow us to visualize two RNA species simultaneously. Using this system, we demonstrate that bicoid assembles into multi-copy RNPs during the active maintenance stage of its localization and anchoring. We show that this co-assembly does not require the nucleotides hypothesized to facilitate dimerization of two bcd transcripts. In addition, we have identified a novel role for the gene squid in the localization of bicoid, and show that there is differential function of the different Sqd isoforms in this regulation. Using a live imaging approach, we show that the active maintenance phase of bicoid localization persists in squid mutants, resulting in mislocalization of the mRNA.