Phagocyte motility is critical for neutrophil (PMN) and monocyte participation in the inflammatory response. Integrated interaction of F-actin based microfilamentous and microtubule (MT) based microtubular cytoskeletal controls phagocyte motility. Preliminary studies originating with a patient's immotile PMNs which had F-actin rich, hair-like surface projections, and defective actin polymerization led to description of new disease, NAD47/89, with increased amounts of LSP1, as actin binding protein. LSP1 is a leukocyte phosphoprotein with only 1 actin binding site, which is regulated in its ability to bind F-actin and inhibit actin polymerization in vitro. Despite having only one actin binding site, LSP1 bundles F-actin in cells, when increased it creates an interlaced F-actin network which forms F-actin rich- hair like projections on cells and it co-sediments with MT and co-localizes with MT and F-actin in phagocytes. The Applicant hypothesizes LSP1 forms a critical, phosphorylation regulated MT-to-f-actin link in phagocytes which regulates integrated (MT and F-actin) cytoskeletal structure and motile function of phagocytes. The proposal;
s specific aims are:) to determine the effect of LSP1 absence and presence in varied dose, in cytoskeletal structure and motility of phagocytes. Natural LSP1- cells and LSP1- cells stably transfected and expressing LSP1 CDNA and LSP+ cells rendered LSP-by antisense will be examined for a range of motile function thought to require integrated cytoskeletal activity; 2) to determine the role of myristoylation, MT binding, self association and heterologous complex formation with 90 and 180 Kd proteins and LSP1 subdomains in creating LSP1's F-actin bundling activity; 3) to determine the role of LSP1 phosphorylation n regulating self association, F-actin bundling activity and MT-1-to-actin linkage in assembly of multi-molecular complex in vitro. The results will elucidate the function and regulation of LSP1 in phagocytes.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL056155-04
Application #
2910617
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1996-05-01
Project End
2001-04-30
Budget Start
1999-05-01
Budget End
2001-04-30
Support Year
4
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of Alabama Birmingham
Department
Pediatrics
Type
Schools of Medicine
DUNS #
004514360
City
Birmingham
State
AL
Country
United States
Zip Code
35294
Li, Y; Zhang, Q; Aaron, R et al. (2000) LSP1 modulates the locomotion of monocyte-differentiated U937 cells. Blood 96:1100-5