Glomerulonephritis is most commonly an autoimmune-induced inflammatory event wherein infiltration of the kidney by macrophages results in loss of renal function due to fibrosis. The long-term goal of our laboratory is to identify the molecular switches that govern macrophage adhesion and thus regulate the inflammatory response. We previously identified tyrosine phosphorylation of 23 integrin adhesion receptors as one such switch and have demonstrated that 23 phosphorylation is necessary for macrophage adhesion to some ligands. Blockade of 23 phosphorylation results in loss of adhesion due to a failure of the actin cytoskeleton to organize into stress fibers. In this application we present evidence that this unique mechanism is required for macrophage entry into renal tissues. We hypothesize that macrophage passage through renal basement membrane is mediated by an interaction between the proteoglycan agrin and phosphorylated 23 integrins. In this application we will assess the role of 23 integrins and their phosphorylation in migration to renal tissues during experimental glomerulonephritis. We will determine whether agrin in renal basement membrane regulates macrophage infiltration by in vitro transmigration studies. We will characterize the production of macrophage podosomal adhesions and pseudopods that are required for migration into three-dimensional tissues by TIRF microscopy of living macrophages. We will biochemically determine the signaling from phosphorylated 23 that controls actin cytoskeletal reorganization in the macrophage pseudopod and podosome. Identification of mechanisms used during organ-specific macrophage immune trafficking can provide novel targets for therapeutic intervention and complement global immune-suppressive therapies.

Public Health Relevance

r laboratory has identified a new mechanism of white blood cell adhesion to tissues. This research proposal will determine whether a particular adhesion molecule called 23 integrin, found on a subset of white blood cells, contributes to glomerulonephritis (inflammation of the kidneys). Understanding the mechanism of glomerulonephritis can provide new targets for drugs to reduce the progression of this disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK079884-04
Application #
8232084
Study Section
Intercellular Interactions (ICI)
Program Officer
Flessner, Michael Francis
Project Start
2009-04-16
Project End
2014-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
4
Fiscal Year
2012
Total Cost
$334,680
Indirect Cost
$121,508
Name
Upstate Medical University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
058889106
City
Syracuse
State
NY
Country
United States
Zip Code
13210
Krainer, Elisabeth C; Ouderkirk, Jessica L; Miller, Eric W et al. (2013) The multiplicity of human formins: Expression patterns in cells and tissues. Cytoskeleton (Hoboken) 70:424-38
Yagi, Mayumi; Murray, Jacqueline; Strand, Kurt et al. (2012) Heparin modulates the conformation and signaling of platelet integrin ýýIIbýý3. Thromb Res 129:743-9
Mersich, Akos T; Miller, Matthew R; Chkourko, Halina et al. (2010) The formin FRL1 (FMNL1) is an essential component of macrophage podosomes. Cytoskeleton (Hoboken) 67:573-85
Christophi, George P; Panos, Michael; Hudson, Chad A et al. (2009) Macrophages of multiple sclerosis patients display deficient SHP-1 expression and enhanced inflammatory phenotype. Lab Invest 89:742-59
Gao, Chunlei; Blystone, Scott D (2009) A Pyk2-Vav1 complex is recruited to beta3-adhesion sites to initiate Rho activation. Biochem J 420:49-56