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Poster Full Abstracts - Drosophila Models of Human Diseases
Poster board number is above title. The first author is the presenter
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that the ability of PRL to slow cell growth under normal conditions is dependent on tight association of PRL with the plasma membrane, we will investigate
if this localization is disrupted under conditions when PRL fails to counter oncogenic activity. A more complete understanding of PRLs will allow
applications using these proteins as markers for metastasis to be better informed and thus, more effective.
388A
Neurofibromin (
Nf1
) function in Drosophila: Genetic and Physical Interactions Screens.
James A. Walker
1,2
, Jean Y. Gouzi
1
, Robert Maher
1
, Andre
Bernards
1,2
. 1) Massachusetts General Hospital Cancer Center, Harvard Medical School, MA; 2) Center for Human Genetic Research, Massachusetts
General Hospital, Harvard Medical School, MA.
Neurofibromatosis type 1 (NF1) affects 1 in 3,000 life births and is the most common genetic disease associated with an increased cancer risk. NF1
patients are predisposed to developing multiple symptoms, including benign but often numerous and disfiguring tumors associated with peripheral nerves,
termed neurofibromas, as well as malignant peripheral nerve sheath tumors. Loss of NF1 expression is also common in glioblastoma, neuroblastoma, and
other non-NF1-associated tumors. The protein encoded by
NF1
, Neurofibromin, is a GTPase Activating Protein for Ras. However, the exact molecular and
cellular defects responsible for NF1 are unknown. We have created a Drosophila model of NF1 and identified several phenotypes of null mutants, including
an overall growth deficiency and a learning/memory deficit, both resembling symptoms of human NF1 and related RASopathies. Neurofibromin functions in
larval neurons to regulate growth non-cell-autonomously. To identify dominant
Nf1
size modifiers we have conducted a genetic screen using deficiencies on
the X and 2nd chromosomes. We have identified the neuronal receptor tyrosine kinase Alk and its ligand Jellybelly (
Jeb
) as rate-limiting upstream activators
of Ras pathways responsible for NF1-regulated growth control, as well as learning defects in adult flies (Gouzi et al., 2011, PLoS Genet 7(9): e1002281). To
complement our genetic screens, we have also conducted proteomic analyses to look for proteins that physically associate with Neurofibromin in neurons.
Studies using Neurofibromin bearing conserved point mutations from NF1 patients have revealed specific altered interactions that may be relevant for
disease. We will present results from both screens that implicate Neurofibromin in novel functions in neurons and discuss the possible implications for
human disease.
389B
Suppression of DiscsLarge ovarian tumor invasion and growth by a novel class of “wounded tumor” loci.
Min Zhao, Scott Goode. Dept Pathology,
Baylor Col Medicine, Houston, TX.
Tumor suppressor DiscsLarge (Dlg) localizes at the basolateral junction of follicle cells (FCs) to stabilize the epithelium. In Drosophila, loss of Dlg results
in invasive tumor to develop. To identify the molecules utilized by dlg tumor cells to grow and invade we completed a genome-wide suppressor screen.
Here, we report a novel class of suppressors, named “wounded tumor”, which had a unique phenotype of epithelium wound. Four genomic loci were
recovered from the screen and CG11583 (renamed holey) was identified at one of them. Reducing Holey inactivated wound repair pathway JNK in dlg
tumor cells specifically and the tumor atrophy and epithelium wound were observed during endocycle, a modified cell cycle in the absence of cell division
under the control of endoreplication regulator dMyc (dm). Our data suggested that tumor shrinkage resulted from nuclear condensation whereas wound was
caused by FC growth retardation and subsequent epithelium rupture. Holey also suppressed tumors derived from Dlg signaling pathway members Warts
(Wts) or Yorki (Yki) during endocycle. Holey protein localized to the nuclei and was essential to maintain constitutive heterochromatin structure and ensure
FC survival during endocycle. Holey phenotypes were likely to associate with dMyc in that they resembled each other’s phenotypes and Holey expression
was controlled by dMyc. To model “wounded tumor” in human, we knocked down (KD) hDlg and hBrix1, the human homologues of Drosophila Dlg and
Holey in the Immortal Ovarian Surface Epithelial (IOSE) cells. The double KD of Dlg and Brix1 cells were less favorable to survive when co-cultured with
Dlg single KD cells. Taken together, we propose that Holey was required for follicle cell growth and survival under the control of dMyc. Removal half of
Holey was sufficient to induce dlg tumor dystrophy whereas it had no damage on animal’s health. Since Dlg is lost in several human ovarian cancer cell
lines and Holey is conserved in human, targeting “wounded tumor” human homologs may be a way to eliminate cancer cells.
390C
Using
Drosophila
to study functional relevance of conserved heart genes.
James H Catterson
1
, Pierre O Bagnaninchi
2
, Anthony J Harmar
1
, Margarete MS
Heck
1
, Paul S Hartley
1
. 1) Centre for Cardiovascular Science, Queen’s Medical Research Institute, University Of Edinburgh, 47 Little France Crescent,
Edinburgh, United Kingdom, EH16 4TJ; 2) MRC Centre for Regenerative Medicine, Chancellor’s Building, University Of Edinburgh, 49 Little France
Crescent, Edinburgh, United Kingdom, EH16 4SB.
Drosophila melanogaster
is increasingly utilised as a model of heart development and function due to its unparalleled genetic toolbox and fast
experimental turnaround. We utilised the Fly Atlas database (the fruit fly gene expression atlas) to identify genes enriched in the adult fly heart that have
high sequence homology with human genes. We are screening these genes experimentally to establish if they have a role in heart development and/or
function. We identified 5927 genes represented 4/4 times in Fly Atlas microarrays. Of these, 164 genes showed heart-enriched expression (>5-fold vs. whole
fly), 149 of these genes were protein-coding, and 59 of these genes had clear human homologues. Genes identified included well-known ‘heart’ genes, e.g.
Tinman, Neuromancer, Pannier, Seven Up - thus validating our
in silico
strategy. One candidate heart gene identified, Fermitin 1 (
Fit1
) - an integrin-
associated protein with 47% identity with its human homologue (Kindlin 2) - was shown to display the same localisation at z-disks in cardiomyocytes as
KIND2. In agreement with circadian microarray data on mouse heart and liver tissue,
Fit1
displayed a diurnal rhythm in expression and this diurnality (of
KIND2) was confirmed in HepG2 cells. Kindlin-2
-/-
null mouse embryos die before cardiogenesis, making it very difficult to investigate how Kindlin-2 is
involved in heart development and function. Therefore, we anticipate that study of
fit1
animals will shed additional light on the function of this gene during
development and tissue morphogenesis. With our tools, the fruit fly will be an excellent model to study the function of these genes in the adult heart and will
lead to further enlightenment of their function in the mammalian heart.
391A
DHR96 regulates cellular cholesterol homeostasis via the Niemann-Pick disease Type C genes.
Akila Gopalakrishnan, Kirst King-Jones. CW405
Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada.
Cholesterol is an essential component of animal cell membranes and the principal precursor for steroid hormone synthesis, and cellular cholesterol levels