Domain-specific Interactions between Entactin and Neutrophil Integrins:

doi:10.1074/jbc.271.48.30587

Domain-specific Interactions between Entactin and Neutrophil Integrins:

G2 DOMAIN LIGATION OF INTEGRIN α₃β₁ AND E DOMAIN LIGATION OF THE LEUKOCYTE RESPONSE INTEGRIN SIGNAL FOR DIFFERENT RESPONSES*

From the ^‡Research Service, Truman Veterans Administration Medical Center, and the Departments of Pharmacology and Molecular Microbiology and Immunology, University of Missouri-Columbia, Columbia, Missouri 65201, the
^¶ Department of Pediatrics, Washington University, St. Louis, Missouri 63110, the
^∥ Respiratory and Critical Care Division, Department of Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, Missouri 63110, and the
** Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260

^§ To whom correspondence should be addressed:
Rm. 379, BMSB, University of New Mexico School of Medicine, Albuquerque, NM 87131-5276.

Abstract

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 β₃-like integrin, leukocyte response integrin, and signaling for chemotaxis. Moreover, the G2 domain signals for stimulation of Fc receptor-mediated phagocytosis via ligation of α₃β₁. 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.

Footnotes

↵* This work was supported in part by the Medical Research Service, Department of Veterans Affairs (to H. D. G), and PHS, National Institutes of Health Grants CA-21246 (to A. E. C.), HL-29594 (to R. M. S.), and AI-36309 (to I. L. G.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

PMN

polymorphonuclear neutrophil

EIgG

IgG-opsonized sheep erythrocytes

GST

glutathione-S-transferase

hpg

high power grid

HSA

human serum albumin

HBSS

Hanks' balanced salt solution

BSA

bovine serum albumin

IAP

integrin-associated protein

LRI

leukocyte response integrin

PDBu

phorbol 12,13-dibutyrate

fMLP

N-formyl-methionyl-leucyl-phenylalanine

mAb

monoclonal antibody

CHO

Chinese hamster ovary

EGF

epidermal growth factor.
- Received February 21, 1996.
- Revision received August 19, 1996.