SUNDAY, DECEMBER 4- Late Abstracts 1 - Molecular Biology of the ...

2043
The Drosophila Transcription Factor Protein Interactome.
D. Y. Rhee 1 , B. Zhai 1 , C. Wong 1 , C. Beekman 1 , S. Gygi 1 , R. Obar 1 , S. Artavanis-Tsakonas 1 ;
1 Department of Cell Biology, Harvard Medical School, Boston, MA
SUNDAY
From the earliest embryo to the adult, the spatiotemporal expression of genes is essential for
normal development and physiology. At the basis of this is the regulation of transcription via
transcription factors (TFs), proteins that physically bind DNA to activate or suppress gene
expression. As the target of signaling pathways, TFs represent a crucial point of regulation
relating to the vast majority of cellular processes and as a rule function through interactions with
other proteins. Consequently, the characterization of protein-protein interactions involving TFs is
essential for understanding how they function to regulate gene expression and, in turn, the
biology of the cell. Towards this end, we have generated a co-AP/MS-based interaction map
encompassing more than 500 from the total of 750 TFs estimated, by various criteria, to
represent the entire gamut of TFs in Drosophila melanogaster.
Cell Migration and Motility
2044
Macrophage Strength: Quantifying Phagocytic Forces and Kinetics.
N. Sosale 1 , T. Rouhi 2 , P. Rodriguez 1 , R. Lipowsky 2 , D. Discher 1 ; 1 Biophysical Engineering Lab,
University of Pennsylvania, Philadelphia, PA, 2 Max Planck Institute of Colloids and Interfaces,
Potsdam, Germany
Macrophages act as immunological gatekeepers at the interface of tissue, blood, and lymph as
these cells take up antigens from the extracellular environment and then present them to the
immune system stimulating lymphocytes. We have studied the force and kinetics of
phagocytosis by human macrophages. To this aim, we studied phagocytosis of opsonized red
blood cells. The force calculation is based on blood cell's shape deformation and elastic
properties. Our analysis shows that the range of the resultant force imposed by Macrophages is
up to 100 pN and is imparted within 10 minutes after initial contact.
2045
Integrin Linked Kinase Modulates Phagocytosis through Rac1 Activation in Epidermal
Keratinocytes.
S. Sayedyahossein 1,2 , L. Nini 1 , L. Dagnino 1,2 ; 1 Physiology and Pharmacology, The University of
Western Ontario, London, ON, Canada, 2 Children’s Health Research Institute, London, ON,
Canada
Integrin linked kinase (ILK) is an adaptor protein that regulates numerous biological processes,
such as cell survival and migration. ILK is also essential for keratinocyte interactions with the
extracellular matrix and development of polarity, but the exact role of ILK in other epidermal
functions, such as melanosome phagocytosis, is not clear. We examined alterations in
phagocytic capacity in ILK-deficient epidermal keratinocytes, using 0.5-µm latex microspheres.
Inactivation of the Ilk gene resulted in severe impairment of microsphere uptake. Further,
stimulation of the keratinocyte growth factor (KGF) receptor or PAR-2 failed to increase
phagocytosis in these cells. Activation of ERK in response to KGF stimulation is unaltered in
ILK-deficient keratinocytes, indicating that the KGF receptor likely signals normally in the
absence of ILK. In contrast, ILK deficiency was associated with impaired Rac1 activation in
response to KGF. The latter was accompanied by reduced formation of membrane ruffles and