Continual surveillance of tissues by lymphocytes is necessary to control and meditate systemic immune responses. However, aberrant trafficking of lymphocytes, and other leukocytes, results in inflammation. Understanding lymphocyte extravasation at the molecular level may lead to new therapies for inflammatory diseases. Lymphocyte extravasation and migration to selected microenvironments requires the concerted efforts of adhesion molecules and metalloproteases. MDCs (metalloprotease disintegrin cysteine-rich) are a family of cell surface proteins recently identified in several mammalian tissues. Members of this protein family possess domains that are predicted to have both adhesive and proteolytic functions. We hypothesize that members of the MDC protein family function in leukocyte extravasation. To investigate this, lymphocytes were initially examined for the expression of MDC proteins. We have isolated a novel member of this family, MDC-L, that appears to be specifically expressed by lymphocytes as both a transmembrane and secreted form.
The aims of this project are to examine the expression and function of MDC-L. Both immunohistochemical and flow cytometric approaches will be used to examine the phenotype of MDC-L expressing lymphocytes and the microenvironments each MDC-L form are found. Integrin recognition of the MDC-L disintegrin domain will be investigated using a combination of biochemical methods. Once the identity of the integrin that recognizes MDC-L is determined, a site directed mutagenesis, monoclonal antibody (mAb), and synthetic peptide approach will be used to determine the molecular aspect of MDC-L recognition by that integrin. The mAbs and peptides produced that inhibit integrin binding will be used to investigate the role of MDC-L as an adhesion molecule in in vitro lymphocyte transmigration assays. The substrate specificity of the metalloprotease domain will be determined. Anti-MDC-L mAbs produced during the course of this project and existing inhibitors of metalloproteases will be assessed for MDC-L inhibitory activity. These protease inhibitors will be used to assess the function of the MDC-L metalloprotease in in vitro lymphocyte transmigration assays. Like many matrix metalloproteases, MDC-L may be synthesized as a zymogen that is activated upon removal of the prodomain. The regulation of the metalloprotease will be investigated by recombinant expression of mutant MDC-L constructs and assaying for metalloprotease activity. The results obtained from this project may identify a new class of potential therapeutic targets, such as MDC-L, for intervention of lymphocyte extravasation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI047314-02
Application #
6374473
Study Section
Pathobiochemistry Study Section (PBC)
Program Officer
Hackett, Charles J
Project Start
2000-04-01
Project End
2005-03-31
Budget Start
2001-04-01
Budget End
2002-03-31
Support Year
2
Fiscal Year
2001
Total Cost
$217,113
Indirect Cost
Name
University of Oklahoma Health Sciences Center
Department
Biochemistry
Type
Schools of Medicine
DUNS #
937727907
City
Oklahoma City
State
OK
Country
United States
Zip Code
73117
Bridges, Lance C; Sheppard, Dean; Bowditch, Ron D (2005) ADAM disintegrin-like domain recognition by the lymphocyte integrins alpha4beta1 and alpha4beta7. Biochem J 387:101-8
Bridges, Lance C; Bowditch, Ron D (2005) ADAM-Integrin Interactions: potential integrin regulated ectodomain shedding activity. Curr Pharm Des 11:837-47
Bridges, Lance C; Hanson, Krista R; Tani, Patricia H et al. (2003) Integrin alpha4beta1-dependent adhesion to ADAM 28 (MDC-L) requires an extended surface of the disintegrin domain. Biochemistry 42:3734-41
Tani, Patricia H; Loftus, Joseph C; Bowditch, Ron D (2002) In vitro selection of fibronectin gain-of-function mutations. Biochem J 365:287-94
Bridges, Lance C; Tani, Patricia H; Hanson, Krista R et al. (2002) The lymphocyte metalloprotease MDC-L (ADAM 28) is a ligand for the integrin alpha4beta1. J Biol Chem 277:3784-92
Kauf, A C; Hough, S M; Bowditch, R D (2001) Recognition of fibronectin by the platelet integrin alpha IIb beta 3 involves an extended interface with multiple electrostatic interactions. Biochemistry 40:9159-66