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Poster Full Abstracts - Cell Biology and Signal Transduction
Poster board number is above title. The first author is the presenter
202
activates Yorkie through Jun kinase signaling, and that Jun kinase activation is necessary, but not sufficient, for the disruption of apical-basal polarity
associated with loss of lethal giant larvae. Our observations identify Jnk signaling as a modulator of Hippo pathway activity in wing imaginal discs, and
implicate Yorkie activation in compensatory cell proliferation and disc regeneration.
262A
Using
Drosophila
to Understand the Biology of Deubiquitinating Enzymes.
Sokol V. Todi, Wei-ling Tsou, Kelly M. McGregor. Departments of
Pharmacology & Neurology, Wayne State University School of Medicine, Detroit, MI USA.
Post-translational modification of proteins by ubiquitin regulates most cellular pathways and processes. Ubiquitin - an evolutionarily conserved 8.5 kDa
protein expressed in all eukaryotic cells - modulates the interaction properties, functions, or fate of proteins to which it is conjugated. Like other types of
post-translational modification, ubiquitination is reversible. Indeed, the process of deubiquitination is vital for normal cellular functions. Deubiquitination is
accomplished by deubiquitinating enzymes (DUBs). While a significant body of work has elucidated the function of several DUBs, little is known about the
biology of the majority of these enzymes, particularly in intact animals. Here, we describe targeted genetic screens to examine the importance of DUBs in
Drosophila development and function. Through amino acid sequence analyses we identified nearly 30 fly DUBs with human orthologues that align at
catalytic and non-catalytic domains. RNAi-mediated knockdown of these DUBs ubiquitously, in the nervous system, or only in fly eyes that express toxic
proteins isolated several DUBs important for fly development, motility, flight and survival. Most DUB studies thus far have been conducted in yeast or
mammalian cell lines. Our work establishes
Drosophila
as a versatile model organism to study the biology DUBs in an intact animal with real physiological
and morphological readouts.
263B
Dissecting the Fat/Dachsous pathway's role in planar cell polarity using chromatin immunoprecipitation to find targets of Atrophin.
Kelvin
Yeung
1,2
, Helen McNeill
1,2
. 1) Research, Samuel Lunenfeld Res Inst, Toronto, Ontario, Canada; 2) Molecular Genetics, University of Toronto, Toronto,
Ontario, Canada.
Planar cell polarity (PCP) is the phenomenon in which epithelial cells are polarized in the plane of the epithelium, orthogonal to the apicobasal axis. PCP is
evident in several Drosophila tissues such as the orientation of hairs on the Drosophila wing and the proper rotation of photoreceptor clusters in the
Drosophila eye. There are several signalling pathways that establish PCP, one of which is the fat/dachsous (ft/ds) signalling pathway. Atrophin (Atro, also
known as Grunge) is a downstream component in the ft/ds pathway and Atro is a nuclear co-repressor. However the downstream target genes of Atro in the
ft/ds pathway remain unknown. In order to identify Atro’s target genes that play a role in PCP, we plan to use chromatin immunoprecipitation against Atro
followed by microarray in the developing Drosophila eye discs and embryos. I have made a transgenic fly line carrying a UAS 3xFLAG Atro construct. I
have shown the fly is able to express the protein in eye discs by immunoprecipitation. I also have preliminary results showing enrichment of a potential
target of Atrophin in the eye discs using end point PCR.
264C
Activating transcription factor-3 regulates stem cell homeostasis in the Drosophila intestine.
Jun Zhou, Anna-Lisa Boettcher, Michael Boutros. German
Cancer Research Center (DKFZ), Div. Signaling and Functional Genomics and Heidelberg University, D-69120 Heidelberg.
Activating transcription factor 3 (ATF3) is a member of the CREB/ATF family of transcription factors, and its exact role in cancer progression is discussed
controversially because both tumor suppressive and oncogenic effects have been described. Tissue homeostasis is controlled through stem cell renewal and
differentiation of progenitor cells. The Drosophila midgut contains intestinal stem cells that could self renew and produce differentiated cells during life time
and different stresses. A number of molecular pathways involved in intestinal stem cell (ISC) proliferation and differentiation has been identified in
Drosophila, which are often remarkable conserved in the mammalian intestine. We have previously shown that Ras signaling regulates innate immune
responses and ISC proliferation(1). Here, we have analyzed the contribution of putative downstream transcription factors. We found that RNAi knockdown
of dATF3 in ISCs led to a dramatic increase in the number of esg-positive cells and promoted stem cell differentiation. Delta and Phospho-histone H3
staining confirmed the ISCs hyperproliferation phenotype. Gene regulating cell-cycle (Cyclin E) and apoptosis (Caspase 3) were highly induced in fly gut
after depletion of dATF3. We are currently investigating whether dATF3 is transcriptional control of gene involved in ISCs proliferation and which pathway
dATF3 interact with to maintain intestine homeostasis. (1) Ragab, A., Buechling, T., Gesellchen, V., Spirohn, K., Boettcher, A.-L., and Boutros, M. (2011).
Drosophila Ras/MAPK signalling regulates innate immune responses in immune and intestinal stem cells. EMBO J 30, 1123-1136.
265A
Characterization of novel epidermal growth factor receptor target genes implicated in
Drosophila
egg and wing development.
Jacquelyn Gallo, Luke
Dombert, Bethany Guarilia, David Marr, Erica Naperkowski, Nicholas Sweeney, Lisa Kadlec. Dept. of Biology, Wilkes University, Wilkes-Barre, PA.
Signaling by the
Drosophila
epidermal growth factor receptor (Egfr) plays an important role in many aspects of development, including oogenesis,
embryogenesis and proper development of both the eye and the wing. In the ovary, the Egfr pathway plays a key role in the establishment of the body axes
during oogenesis. In the wing, Egfr signaling plays an important role in vein tissue specification. Microarray screens by our lab and others have been used to
identify potential downstream transcriptional targets of the Egf receptor using the
Drosophila
ovary as a model system. Our initial work compared gene
expression using fly ovaries in which the activity of the Egfr-pathway was reduced (grk HK36), normal (OreR), or constitutively active (CY2/λTop). We are
now employing a number of approaches to investigate the expression, biological function, and mechanism of action of several putative targets of interest.
Among the target genes currently under investigation are several genes implicated in eggshell formation and/or as part of chorion amplicons (such as
Defective Chorion-1
, CG18419 and yellow-G2), and a number of genes of unknown function (including CG11381, CG13083 and CG14309). RT-PCR has
confirmed the up-regulation of several targets, as originally seen by microarray. A number of putative targets demonstrate developmentally regulated
expression in the ovary, and in some cases this expression has been shown to be altered in response to changes in levels of Egfr signaling. Screening of
putative targets for biological function using UAS-RNAi suggests roles for several target genes of unknown function in eggshell and/or wing
morphogenesis. We are also using
in situ
hybridization to investigate gene expression in wing imaginal discs and to evaluate the effectiveness of our targeted
RNA interference, and a neutral red uptake assay to assess vitelline membrane integrity in compromised eggshells.