Download Symposium Poster - uospur

Brian
1
Rodriguez ,
Michael
2,
Spinner Tory
2
Herman
1. Department of Biological Sciences, Texas Tech University, Lubbock, Texas
2. Institute of Molecular Biology, University of Oregon, Eugene, Oregon
Abstract: Defects in the development and formation of synapses can cause neuronal and synaptic overgrowth, which can lead to many neurological disorders including autism. Previous studies have shown that defective FMR1 and ADAR genes result in
synaptic overgrowth in Drosophila neuromuscular junctions (NMJ). It was then found that both genes encode RNA binding proteins and interact together to edit the mRNA of several synaptic transcripts. Through a genetic screen, our lab has identified a
novel gene, CG7706, whose loss show similar defects to these genes. We hypothesize that CG7706 may interact and function similarly to ADAR and FMR1, specifically in its mRNA editing ability.
I tested this hypothesis in a fly model using specified transcripts of proteins involved in neuronal function including stnB, shab, syt1, and Unc-13 . Results indicate that loss of CG7706 has no effect on editing for Unc-13 and shab , however syt1 and stnB
data does suggest that CG7706 may play some role in down regulation of mRNA editing. However, more data is needed to confirm these results. In the future I plan to test more mRNA transcripts , as well as looking to see if the localization or function of
key synaptic protein are disrupted in CG7706 mutants. Additionally I aim to test if CG7706 interacts with FMR1 in pathways outside of editing.. These results give us new molecular insights on neuronal overgrowth and possible therapeutic targets for the
treatment and control of neurological disorders such as autism.
Background
Neurons are the functional units of the nervous system
Preliminary Results
Novel Gene CG7706 Restricts Synaptic Growth
• Human homolog known as Kanadaptin.
• This gene has an mRNA binding domain similar to
ADAR and fmr1
• Preliminary data shows CG7706 knockouts produce
similar neuronal overgrowth to ADAR knockouts.
• Neurons are the basic building block of the
nervous system
• Neurons are connected into circuits by
specialized junctions known as synapses.
Defects in synapse development are associated with cognitive disorders
• FMR1 needs CG7706 in order to restrict synapse
growth.
• CG7706 it is able to suppress the fmr1 phenotype
similar to ADAR
• 7706 may be acting in the same pathway as fmr1 and
possibly ADAR
Loss of FMR1 causes fragile X syndrome
Wild Type
CG7706 is not required for Syt1
mRNA editing
Neither CG7706 nor ADAR is required for
Unc-13 mRNA editing
CG7706 may inhibit stnB mRNA
editing
Control
FMR1 Over
CG7706 CG7706 Loss;
Loss
FMR1 Over
Is CG7706, like ADAR, required for RNA editing?
FMR1 Loss
ADAR also restricts synaptic growth
ADAR Loss
CG7706 is not required for Shab mRNA
editing
CG7706 may be in the same pathway as ADAR and FMR1
• Too few synapses can cause neurological
disorders such as Alzheimer's or Parkinson's
disease while too many synapses can lead to a
different array of neurological disorders such
as autism
• FMR1 also restricts synaptic development in
flies
• When FMR1 is lost, neuronal growth is not
regulated and can cause Autism
Results
Cross
ADAR acts downstream to FMR1
Previous studies have
identified neuronal
• overgrowth
Loss of the ADARto
causes
be synaptic
in overgrowth
• Overexpression of FMR1 causes synaptic
response
to malfunctions
undergrowth
• of
FMR1
inhibitFMR1
synaptic and
growth without
twocannot
genes,
ADAR present.
ADAR, which encode RNA
binding proteins in
Drosophila. that have
been found RNA editing
on synaptic
• capabilities
ADAR must be downstream
of FMR1
• Studies show that ADAR and FMR1 bind mRNA
transcripts
together
Methods
• ADAR converts specified Adenosine (A) base
pairs to inosine (I) base pairs post
transcriptionally
• Ribosomes read the I’s as G’s and then pair it
accordingly
CG7706 may affect editing of specific neural transcripts
• Syt1 may be affected but others need to be
examined
• We found that fmr1 acts through CG77706
• The more we can learn about CG7706 the more
we can learn about how fmr1 works and
prevents autism
Gpeak + Apeak = Ptot
Gpeak = Ratio of Edited mRNA
Ptot
ADAR regulates mRNA editing
Discussion
Shab- Mediates the voltage-dependent potassium ion permeability of excitable membranes
Unc-13- synaptic vesicle fusion
Syt-1- membrane interactions during trafficking of synaptic vesicles at the active zone of the synapse.
stnB- Adapter protein involved in endocytic(s) recycling of synaptic vesicles membranes.
Future Directions
• Test more mRNA transcripts
• Test whether CG7706 is required for non-editing functions of FMR1
Acknowledgements
• Funding for this research came from an NSF REU Site Program in Molecular Biosciences
(NSF 1460735)
• Id also like to thank Sarah and Sasha for their help and tips
• Lastly thanks to the University of Oregon and their Institute of Molecular Biosciences
for allowing me to preform my research here