Insights into the nuclear localization of Scalloped

  • Author / Creator
    Magico, Adam
  • The Drosophila melanogaster protein Scalloped (Sd) is a member of the TEA/ATTS family of transcription factors, present throughout Eukarya. The protein is best known for its involvement in the development of the wing imaginal disc of Drosophila, although roles in nervous system, muscle (both cardiac and somatic), eye and leg development as well as the control of cellular proliferation have also been shown or predicted. Scalloped itself lacks a transcriptional activation domain and thus is thought to rely on binding with transcription intermediary factors (TIFs) which have one or more of these domains. Under this paradigm it is thought that Sd facilitates nuclear localization and targeted DNA binding of the Sd/TIF complex, while the TIF activates the target gene(s). In order to understand the mechanisms behind the nuclear translocation of Sd, it is demonstrated that a candidate bipartite nuclear localization signal is functional in S2 cells, and further that the region containing this signal is critical for Sd function during wing development. Evidence for the presence of a nuclear export signal is also given. Finally, a broad region of the C-terminal domain of Sd is identified as also being required for the proper nuclear localization of the protein. Although several TIFs of Sd have been identified, there are several lines of evidence which make it likely there are others yet to be discovered. Identifying these new factors would shed light on the function of Sd within whichever tissue a new TIF is discovered. With this in mind a candidate-gene approach was used to identify Drosophila vestigial-like 4 (dvgl-4). Herein it is demonstrated that dVgl-4 contains two putative Sd interacting domains and is able to interact with Sd in vitro and ex vivo. It is also shown that this protein is able to act in a dominant negative fashion during wing development, and that there are likely two isoforms of mRNA expressed from this gene, and that the expression of each is likely under the control of different promoters. Finally, over-expression phenotypes are described for several tissues in order to begin elucidating a potential function for dVgl-4 in Drosophila development.

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    Doctor of Philosophy
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