Characterization of RanBPM in Drosophila melanogaster

Abstract

<p>RanBPM is a conserved putative scaffold protein of unknown function. Loss-of-function in <em>RanBPM</em> leads to pleiotropic phenotypes such as reduced locomotion, decreased size and larval lethality in the <em>Drosophila melanogaster</em>.</p> <p><em>dRanBPM</em> mutants have decreased branching and boutons at the neuromuscular junction, which may contribute to their locomotory defect. To investigate if dRanBPM is involved in controlling synaptic architecture at the neuromuscular junction, levels of two cytoskeletal proteins, Futsch and profilin, were assessed in <em>dRanBPM</em> mutants.</p> <p>Due to time constraints, immunoblots for Futsch were not fully optimized for protein measurement. Immunoblots for profilin, on the other hand, were successfully carried out. However, results from the reproduction of a blot demonstrating the negative regulation of <em>Drosophila</em> FMRP on profilin did not agree with that of the literature. In addition, results from an epistatic experiment demonstrated that profilin levels were not affected in FMRP deficient flies when compared to those with additional decrease in dRanBPM function.</p> <p>Targeted expression of <em>dRanBPM</em> to neurosecretory cells is able to rescue size and lethality of <em>dRanBPM</em> mutants, suggesting a common pathway through which both phenotypes operate is disrupted in these mutants. Activation of the insulin signaling pathway was indeed found to be downregulated in <em>dRanBPM</em> mutants. A longevity assay was alternatively carried out to demonstrate decreased insulin pathway activation in <em>dRanBPM</em> mutants. Unfortunately, due to inappropriate controls used for this experiment, no conclusive points can be made. Together, these findings contribute to the knowledge that RanBPM plays and to designing future experiments to test for RanBPM function.</p>