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Poster Full Abstracts - Drosophila Models of Human Diseases
Poster board number is above title. The first author is the presenter
245
Fatty acid activation and neurodegeneration.
Hannah B Gordon, Anna Sivachenko, PhD, Anthea Letsou, PhD. Department of Human Genetics,
University of Utah, Salt Lake City, UT.
Fatty acids are utilized for a variety of cellular needs from energy substrates to membrane components. When a tissue is particularly dependent on these
requirements for fatty acids, it is rendered sensitive to fatty acid metabolism. One tissue that is highly dependent upon fatty acid metabolism is the nervous
system; here fatty acids play a central role in neuronal insulation. We have recently characterized
double bubble
(
dbb
) a gene encoding an acyl-CoA
synthetase (ACS) that displays a neurodegenerative phenotype in the adult fly. ACS proteins are responsible for activating fatty acids for subsequent
utilization as membrane components, signaling molecules and/or energy substrates.
dbb
mutants exhibit a shared loss-of-function phenotype with a
previously characterized mutant in a homologous ACS gene,
bubblegum
(
bgm
). Alone, each of these mutants displays fully penetrant neurodegenerative
phenotypes that are variably expressed. Neurodegenerative phenotypes in
bgm dbb
double mutants, however, are more severely manifested, and thus the
double mutant provides a clearer platform to characterize the roles of ACS proteins and lipid metabolism in neuropathology. In humans, mutations in
conserved proteins in the ACS fatty acid activation pathway are associated with the human diseases adrenoleukodystrophy and adrenomyeloneuropathy;
both of which are characterized by neurodegeneration and signs of altered lipid metabolism such as high circulating very long chain fatty acids (VLCFAs,
>22 carbon chain length). The specific lipid alterations that result from disruption of ACS proteins, as well as the primary mechanism by which altered ACS
activity leads to neurodegeneration are not currently understood in either the Drosophila model or the human disease. Here we provide evidence that the
Drosophila
bgm dbb
double mutant model provides a powerful in vivo platform to elucidate the roles and toxicity of lipids in neuronal cells.
420C
Survival motor neuron protein controls stem cell division, proliferation and growth.
Stuart J. Grice, Sian E. Davies, Jilong Liu. MRC Functional
Genomics Unit, University of Oxford, Oxford, United Kingdom.
Survival motor neuron (SMN) protein facilitates the biogenesis of ribonucleoprotein (RNP) complexes such as the small nuclear RNPs (snRNPs) required
for pre-mRNA splicing. Although SMN is required in all cells, the motor nervous system is particularly sensitive to SMN reduction, with SMN loss causing
the neuromuscular disease spinal muscular atrophy (SMA).
SMN protein is highly upregulated in early embryogenesis and there is increasing evidence to suggest that high levels of SMN are essential for timely
proliferation and growth in multiple tissues. With the current development of therapeutics for SMA, there is an urgent need to comprehensively understand
the transient and local enrichments of SMN required for normal development.
We have previously reported that SMN is enriched in
Drosophila
stem cells, and its loss leads to fewer stem cell divisions, changes in RNP component
levels and localization, and alterations in the timing of differentiation. Our current research is looking at the specific requirement of SMN to control the
switch between proliferation and differentiation. Using clonal analysis in the larval CNS and imaginal discs, as well as
smn
mutants, we have analyzed how
local changes in SMN effect specific stem cell and differentiation factors. We show that high endogenous SMN levels are required for efficient proliferation
and that SMN reduction correlates with a switch to differentiation. From this we hypothesise how a systemic reduction of SMN in early development can
contribute to targeted neuromuscular defects and how reducing SMN levels can modify ectopic proliferation in
Drosophila
.
421A
Genes
Sema-1a
and
Sema-2a
as modifiers of dystrophin gene function in
Drosophila melanogaster
.
Olena Holub, Yaroslava Chernyk, Nataliya Holub.
Genetics and Biotechnology, Ivan Franko National University of Lviv, Lviv, Ukraine.
Muscular dystrophy (MD) refers to a group of genetic diseases characterized by progressive damage and weakness of facial, limb, breathing, and heart
muscles. It is due to the lack of a key protein dystrophin that is needed to maintain the integrity and proper function of the muscle.
Drosophila melanogaster
is an excellent genetically tractable model for searching new approach to treatment dystrophies such as using genes-modifiers of dystrophin gene function.
The aim of our work was to check up influence of genes
Sema-1a
and
Sema-2a
(involved in neuronal migration) as an possible genes-modifiers on mutant
phenotype of dystrophin gene. Mutant strain
NH
2
-Dys
constructed after the method antisense-RNA were used. It is characterized by diminished on 30%
expression of dystrophin gene, defective thorax muscle structure and decreased the index of physical activity (IPA). Offsprings F
1
which contained
supplementary copy of gene-modifier and dystrophin gene inactivation construct were analysed after these indexes. In all crossing systems was observed
restore of thorax muscle structure with the frequency 59% - 61% that is in 10 times higher comparing to the strain
NH
2
-Dys
. In climbing-test was shown
increasing of IPA in progeny
NH
2
-Dys // Sema-1a
in the 2 - 4 times and for hybrids
NH
2
-Dys// Sema-2a
- in 3 - 6 times comparing to strain
NH
2
-Dys
.
Previously was shown that genes
Sema-1a
and
Sema-2a
resumed of wing vein structure with frequency 16% and 44% in strain
NH
2
-Dys
. It could be
concluded that genes
Sema-1a
and
Sema-2a
manifested to be dystrophin - deficiency phenotype suppressors moreover gene
Sema-2a
is more active
suppressor than
Sema-1a
gene.
422B
TPI[sgk] is degraded by the proteasome in a chaperone dependent manner.
Stacy Hrizo
1,2
, Daniel Long
1
, Michael Palladino
2
. 1) Department of Biology,
Slippery Rock University, Slippery Rock, PA; 2) Department of Pharmacology and Chemical Biology, University of Pittsburgh SOM, Pittsburgh, PA.
Triosephosphate isomerase (TPI) deficiency is a severe glycolytic enzymopathy that causes progressive locomotor impairment and neuromuscular
degeneration, susceptibility to infection, and premature death. We previously identified a recessive missense mutation in the TPI allele in Drosophila called
sugarkill that exhibits similar phenotypes as TPI deficient patients such as progressive locomotor impairment, neurodegeneration, and reduced lifespan. In
previously published work, we showed that the TPI[sgk] protein is an active stable dimer however the mutant protein is rapidly turned over by the
proteasome reducing cellular levels of this glycolytic enzyme. We have confirmed the instability of the TPI[sgk] protein with pulse chase analysis of the
protein in primary culture cells derived from embryos. In addition, we hypothesized that TPI[sgk] is recognized by molecular chaperones and components of
the ubiquitin proteasome pathway, resulting in the proteasomal degradation of the mutant protein. In support of this hypothesis, we have detected an
interaction between Hsp70 and Hsp90 and the TPI[sgk] protein. In addition, data collected using complementary pharmacological and genetic experiments
indicate that both Hsp70 and Hsp90 are important for targeting TPI[sgk] for degradation. We have conducted mechanical stress sensitivity assays and
analyzed TPI[sgk] protein levels in order to ascertain whether inhibiting the proteasome with MG132 or the molecular chaperone Hsp90 with geldanamycin,
results in a decreased or exacerbated phenotype. We observed that the mechanical stress sensitivity in TPI[sgk] animals with reduced proteasome, Hsp90 and