Novel Functions for Neuronal RNA Processing Bodies in the Control of Axon Terminal Growth in Drosophila Melanogaster

<p>In this thesis we first characterized neuronal functions for HPat/Pat1, a core component of RNA processing bodies or "P bodies". We show that <em>hpat</em> mutants exhibit a strong synaptic hyperplasia at the developing and acutely stimulated <em>Drosophila</em> larval neuromuscular junctions (NMJs). The synaptic defects observed in hpat mutants are associated with rearrangement of the axonal microtubule cytoskeleton suggesting that HPat negatively regulates presynaptic microtubule-based growth during NMJ development. Interestingly, we also found that both pre-and postsynaptic HPat expression controlled rapid axon terminal growth in response to acute spaced synaptic stimulation. We also demonstrate that HPat interacts genetically with the catalytic subunit of the deadenylase complex (twin/CCR4) and the miRNA pathway (Argonaute 1) to control bouton formation. We propose that HPat is required to target mRNAs involved in the control of microtubule architecture and synaptic terminal growth for repression, presumably in P bodies, via both general and miRNA-mediated mechanisms.</p> <p>Next, we investigated whether HPat interacts with the <em>Drosophila</em> Fragile X Mental Retardation Protein (dFMR1), to regulate neuronal structure in a <em>Drosophila melanogaster</em> fragile X model. First, we demonstrated that HPat interacts biochemically with dFMRP in an RNAse independent manner. Second, we show that HPat genetically interacts with dFmr1 in the<em> Drosophila</em> eye although the phenotype is weak, however we did not see any interaction of <em>hpat</em> and <em>dfmr1</em> to control synaptic structure at the NMJ. Finally, we screened additional P body components that might have function in FMRP mediated translation regulation. Interestingly, a luciferase-based translational repression tethering assays in <em>Drosophila</em> Schneider 2 (S2) cells showed the function of GW182 in FMRP-mediated translation regulation.</p>

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Year dc:date.available

2013

Author dc:creator

• Pradhan, Sarala Joshi

Contributors dc:contributor

• Scott A. Barbee, Ph.D.
• Matthew J. Taylor
• Joseph Angleson
• Todd Blankenship
• Daniel Linseman

• Fragile X mental retardation 1
• Neuromuscular junction
• Pat1
• P bodies
• Ribonucleoprotein particles
• Synaptogenesis
• Genetics
• Genetics and Genomics
• Life Sciences

Statement dc:rights

• <p>Copyright is held by the author. User is responsible for all copyright compliance.</p>

Language dc:language

en

Repository record dc:identifier

https://digitalcommons.du.edu/etd/524

OAI identifier oai:identifier

oai:digitalcommons.du.edu:etd-1523