This competitive renewal application is to continue on-going studies of novel functions of the integrin, alpha9beta1. Based on analysis of alpha9 knockout mice, alpha9beta1 plays a critical role in development of the thoracic duct and other lymphatic vessels. One clue to the mechanism by which this integrin might contribute to lymphatic development comes from our identification of the lymphangiogenic growth factors, VEGFC and VEGFD as putative alpha9beta1 ligands. During the current funding period a unique mechanism by which alpha9beta1 enhances cell migration was also identified, and this effect was shown to be mediated by specific sequences in the alpha9 cytoplasmic domain. A single protein, the enzyme spermine/spermidine acetyltransferase, was found to bind to the alpha9 cytoplasmic domain and to specifically modulate alpha9-dependent enhancement of cell migration. This application proposes to evaluate each of these clues in more detail. The significance of binding of the extracellular domains of alpha9beta1 to VEGFC and D will be examined by assessing cell migration, proliferation, and early steps in integrin and growth factor receptor signaling in response to recombinant forms of each growth factor in mock- and alpha9-transfected cells. The importance of co-ligation of the canonical receptor for these growth factors, VEGFR3 will be assessed by performing all of these studies in the presence or absence of co-expression of VEGFR3. The alpha9 expressing cells critical for lymphatic development will be evaluated in mice homozygous for a conditional alpha9 null allele that will be used to inactivate this gene in specific cell types that might contribute to developing lymphatics. Stable cell lines co-expressing wild type and mutant forms of alpha9beta1 along with wild type or mutant forms of SSAT will be used to map the interaction sites in each protein and determine the importance of SSAT binding and enzymatic activity for alpha9beta1-mediated enhancement of cell migration. In vitro binding of recombinant versions of each protein, co-immunoprecipitation and double staining immunofluorescence will be used to determine whether this interaction is direct, occurs in living mammalian cells and results in co-localization to informative cellular compartments. Finally, the in vivo significance of alpha9-mediated migration and interactions with SSAT will be determined utilizing mice expressing knock-in mutations of the alpha9 cytoplasmic domain specifically designed to eliminate enhanced migration and/or SSAT binding. The proposed studies should provide important information about the role this widely expressed integrin plays in lymphatic development and cell migration and could ultimately lead to the design of novel interventions in diseases affected by each of these processes.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Study Section
Lung Biology and Pathology Study Section (LBPA)
Program Officer
Blaisdell, Carol J
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University of California San Francisco
Internal Medicine/Medicine
Schools of Medicine
San Francisco
United States
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Xu, Pinglong; Bailey-Bucktrout, Samantha; Xi, Ying et al. (2014) Innate antiviral host defense attenuates TGF-? function through IRF3-mediated suppression of Smad signaling. Mol Cell 56:723-37
Kudo, Makoto; Melton, Andrew C; Chen, Chun et al. (2012) IL-17A produced by ?? T cells drives airway hyper-responsiveness in mice and enhances mouse and human airway smooth muscle contraction. Nat Med 18:547-54
Kon, Shigeyuki; Atakilit, Amha; Sheppard, Dean (2011) Short form of ýý9 promotes ýý9ýý1 integrin-dependent cell adhesion by modulating the function of the full-length ýý9 subunit. Exp Cell Res 317:1774-84
Nishimichi, Norihisa; Hayashita-Kinoh, Hiromi; Chen, Chun et al. (2011) Osteopontin undergoes polymerization in vivo and gains chemotactic activity for neutrophils mediated by integrin alpha9beta1. J Biol Chem 286:11170-8
Melton, Andrew C; Bailey-Bucktrout, Samantha L; Travis, Mark A et al. (2010) Expression of ?v?8 integrin on dendritic cells regulates Th17 cell development and experimental autoimmune encephalomyelitis in mice. J Clin Invest 120:4436-44
Bazigou, Eleni; Xie, Sherry; Chen, Chun et al. (2009) Integrin-alpha9 is required for fibronectin matrix assembly during lymphatic valve morphogenesis. Dev Cell 17:175-86
Atabai, Kamran; Jame, Sina; Azhar, Nabil et al. (2009) Mfge8 diminishes the severity of tissue fibrosis in mice by binding and targeting collagen for uptake by macrophages. J Clin Invest 119:3713-22
Singh, Purva; Chen, Chun; Pal-Ghosh, Sonali et al. (2009) Loss of integrin alpha9beta1 results in defects in proliferation, causing poor re-epithelialization during cutaneous wound healing. J Invest Dermatol 129:217-28
deHart, Gregory W; Jin, Taihao; McCloskey, Diane E et al. (2008) The alpha9beta1 integrin enhances cell migration by polyamine-mediated modulation of an inward-rectifier potassium channel. Proc Natl Acad Sci U S A 105:7188-93
Araya, Jun; Cambier, Stephanie; Markovics, Jennifer A et al. (2007) Squamous metaplasia amplifies pathologic epithelial-mesenchymal interactions in COPD patients. J Clin Invest 117:3551-62

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