Date of Award


Document Type


Degree Name


First Advisor

Scott A. Barbee, Ph.D.

Second Advisor

Matthew J. Taylor

Third Advisor

Joseph Angleson

Fourth Advisor

Todd Blankenship

Fifth Advisor

Daniel Linseman


Fragile X mental retardation 1, Neuromuscular junction, Pat1, P bodies, Ribonucleoprotein particles, Synaptogenesis


In this thesis we first characterized neuronal functions for HPat/Pat1, a core component of RNA processing bodies or "P bodies". We show that hpat mutants exhibit a strong synaptic hyperplasia at the developing and acutely stimulated Drosophila 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.

Next, we investigated whether HPat interacts with the Drosophila Fragile X Mental Retardation Protein (dFMR1), to regulate neuronal structure in a Drosophila melanogaster 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 Drosophila eye although the phenotype is weak, however we did not see any interaction of hpat and dfmr1 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 Drosophila Schneider 2 (S2) cells showed the function of GW182 in FMRP-mediated translation regulation.

Publication Statement

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Rights Holder

Sarala Joshi Pradhan


Received from ProQuest

File Format




File Size

129 p.


Developmental biology, Biology, Neurosciences

Included in

Genetics Commons