Association of cytoskeletal re-organization with capping of the complement decay-accelerating factor on T lymphocytes.
Recent studies have identified cell-associated proteins that are membrane anchored by glycosyl-inositol-phospholipid structures but the biologic implications of this mode of membrane attachment are incompletely understood. Among proteins anchored in this way is the decay-accelerating factor (DAF), a complement (C) regulatory factor that functions on blood cell surfaces to prevent autologous C attack. As one approach to investigate the functional consequences of glycosyl-inositol-phospholipid-anchoring of DAF in T lymphocytes, the effects of crosslinking surface DAF molecules were compared to those of crosslinking conventionally by anchored cluster of differentiation (CD) proteins. Upon incubation with anti-DAF mAb and anti-murine IgG, DAF re-distributed to a pole of the cell with a t1/2 at 37 degrees C of 4.4 min as compared to t1/2 of 3.5 to 7 min for CD3, CD4, and CD8. Re-distribution of DAF occurred independently of CD2, CD3, CD4, or CD8. Anti-DAF immunoprecipitates of membrane extracts of cells chemically cross-linked with dithiobis(succinimidylpropionate) contained only monomeric DAF. Immunofluorescent staining demonstrated clustered actin, tubulin, and vimentin beneath the capped DAF protein. Pre-treatment of cells with colchicine or 8-azidoadenosine 3',5'-cyclic phosphate, but not lumicolchicine, resulted in reduction of the t1/2 for DAF to 1 to 2.6 min. Conversely, treatment of cells with cytochalasins B or D completely blocked DAF capping. The results indicate that, upon cross-linking, glycosyl-inositol-phospholipid-anchored DAF molecules undergo capping similar to conventionally anchored CD molecules and that DAF capping is associated with cytoskeletal reorganization.
Kammer
G M
GM
Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44106.
Walter
E I
EI
Medof
M E
ME
D000328:Adult; D000945:Antigens, Differentiation, T-Lymphocyte; D018958:CD55 Antigens; D003285:Contractile Proteins / Q000276:immunology / Q000378:metabolism; D003432:Cross-Linking Reagents; D003598:Cytoskeletal Proteins / Q000276:immunology / Q000378:metabolism*; D003599:Cytoskeleton / Q000276:immunology / Q000502:physiology; D006801:Humans; D007152:Immunologic Capping; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000032:analysis / Q000276:immunology / Q000378:metabolism*
D000945:Antigens, Differentiation, T-Lymphocyte; D018958:CD55 Antigens; D003285:Contractile Proteins; D003432:Cross-Linking Reagents; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins