Activated platelets form protected zones of adhesion on fibrinogen and fibronectin-coated surfaces. J Cell Biol 1993 May;121(4):945-55
Date
05/01/1993Pubmed ID
8491785Pubmed Central ID
PMC2119798DOI
10.1083/jcb.121.4.945Scopus ID
2-s2.0-0027262210 (requires institutional sign-in at Scopus site) 15 CitationsAbstract
Leukocytes form zones of close apposition when they adhere to ligand-coated surfaces. Because plasma proteins are excluded from these contact zones, we have termed them protected zones of adhesion. To determine whether platelets form similar protected zones of adhesion, gel-filtered platelets stimulated with thrombin or ADP were allowed to adhere to fibrinogen- or fibronectin-coated surfaces. The protein-coated surfaces with platelets attached were stained with either fluorochrome-conjugated goat anti-human fibrinogen or anti-human fibronectin antibodies, or with rhodamine-conjugated polyethylene glycol polymers. Fluorescence microscopy revealed that F(ab')2 anti-fibrinogen (100 kD) did not penetrate into the contact zones between stimulated platelets and the underlying fibrinogen-coated surface, while Fab antifibrinogen (50 kD) and 10 kD polyethylene glycol readily penetrated and stained the substrate beneath the platelets. Thrombin- or ADP-stimulated platelets also formed protected zones of adhesion on fibronectin-coated surfaces. F(ab')2 anti-fibronectin and 10 kD polyethylene glycol were excluded from these adhesion zones, indicating that they are much less permeable than those formed by platelets on fibrinogen-coated surfaces. The permeability properties of protected zones of adhesion formed by stimulated platelets on surfaces coated with both fibrinogen and fibronectin were similar to the zones of adhesion formed on fibronectin alone. mAb 7E3, directed against the alpha IIb beta 3 integrin blocked the formation of protected adhesion zones between thrombin-stimulated platelets and fibrinogen or fibronectin coated surfaces. mAb C13 is directed against the alpha 5 beta 1 integrin on platelets. Stimulated platelets treated with this mAb formed protected zones of adhesion on surfaces coated with fibronectin. These protected zones were impermeable to F(ab')2 antifibronectin but were permeable to 10 kD polyethylene glycol. These results show that activated platelets form protected zones of adhesion and that the size of molecules excluded from these zones depends upon the composition of the matrix proteins to which the platelets adhere. They also show that formation of protected zones of adhesion by platelets requires alpha IIb beta 3 integrins while the permeability properties of these zones of adhesion are regulated by both alpha IIb beta 3 and alpha 5 beta 1 integrins.
Author List
Loike JD, Silverstein R, Cao L, Solomon L, Weitz J, Haber E, Matsueda GR, Bernatowicz MS, Silverstein SCAuthor
Roy L. Silverstein MD Professor in the Medicine department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Blood PlateletsCell Adhesion
Cell Membrane Permeability
Fibrin
Fibrinogen
Fibronectins
Humans
Integrins
Macromolecular Substances
Platelet Activation