Domain-specific interactions between entactin and neutrophil integrins. G2 domain ligation of integrin alpha3beta1 and E domain ligation of the leukocyte response integrin signal for different responses.
Extracellular matrix proteins activate neutrophils to up-regulate many physiologic functions that are necessary at sites of tissue injury. To elucidate the ligand-receptor interactions that mediate these functions, we examined neutrophil activation by the basement membrane protein, entactin. Entactin is structurally and functionally organized into distinct domains; therefore, we utilized glutathione S-transferase -fusion proteins encompassing its four major domains, G1, G2, E, and G3, to assess interactions between entactin and neutrophil integrin receptors. We show that the E domain, which contains the single RGD sequence of entactin, is sufficient for ligation of the beta3-like integrin, leukocyte response integrin, and signaling for chemotaxis. Moreover, the G2 domain signals for stimulation of Fc receptor-mediated phagocytosis via ligation of alpha3beta1. This receptor-ligand interaction was revealed only after stimulation of neutrophil by immune complexes or phorbol esters. Interestingly, the E domain does not enhance phagocytosis, and the G2 domain is not chemotactic. Furthermore, cleavage of entactin with the matrix metalloproteinase, matrilysin, liberates peptides that retain E domain-mediated chemotaxis and G2 domain-mediated enhancement of phagocytosis. These studies indicate that multiple domains of entactin have the ability to ligate individual integrins expressed by neutrophils and to activate distinct functions.
Gresham
H D
HD
Research Service, Truman Veterans Administration Medical Center, Columbia, Missouri 65201, USA.
Graham
I L
IL
Griffin
G L
GL
Hsieh
J C
JC
Dong
L J
LJ
Chung
A E
AE
Senior
R M
RM
D000936:Antigen-Antibody Complex; D015703:Antigens, CD / Q000502:physiology; D001665:Binding Sites; D051928:CD47 Antigen; D002352:Carrier Proteins / Q000502:physiology; D002634:Chemotaxis, Leukocyte; D006801:Humans; D039422:Integrin alpha3; D019012:Integrin beta1 / Q000502:physiology; D016023:Integrins / Q000502:physiology; D008024:Ligands; D016177:Macrophage-1 Antigen / Q000502:physiology; D020783:Matrix Metalloproteinase 7; D008562:Membrane Glycoproteins / Q000502:physiology*; D008666:Metalloendopeptidases / Q000378:metabolism; D009504:Neutrophils / Q000502:physiology*; D009842:Oligopeptides; D010587:Phagocytosis; D011961:Receptors, Fc / Q000502:physiology
D000936:Antigen-Antibody Complex; D015703:Antigens, CD; D051928:CD47 Antigen; C497894:CD47 protein, human; D002352:Carrier Proteins; D039422:Integrin alpha3; D019012:Integrin beta1; D016023:Integrins; D008024:Ligands; D016177:Macrophage-1 Antigen; D008562:Membrane Glycoproteins; D009842:Oligopeptides; D011961:Receptors, Fc; C075596:integrin, leukocyte response; C029967:nidogen; C047981:arginyl-glycyl-aspartic acid; D008666:Metalloendopeptidases; D020783:Matrix Metalloproteinase 7