The lymphocyte metalloprotease MDC-L (ADAM 28) is a ligand for the integrin alpha4beta1.
The interaction of lymphocytes with other cells is critical for normal immune surveillance and response. MDC-L (ADAM 28), a member of the ADAM (a disintegrin and metalloprotease) protein family, is expressed on the surface of human lymphocytes. ADAMs possess a disintegrin-like domain similar in sequence to small non-enzymatic snake venom peptides that act as integrin antagonists. We report here that the disintegrin domain of MDC-L is recognized by the leukocyte integrin alpha(4)beta(1). Recombinant Fc fusion proteins possessing the disintegrin domain of MDC-L supported adhesion of the T-lymphoma cell line, Jurkat, in a concentration- and divalent cation-dependent manner. Adhesion of Jurkat cells to the disintegrin domain of MDC-L was inhibited by an anti-MDC-L monoclonal antibody (mAb), Dis1-1. The epitope for mAb Dis1-1 was localized within 59 residues of the disintegrin domain. Recombinant expression of this 59-residue fragment of the disintegrin domain also supported cell adhesion. Adhesion of Jurkat cells to the MDC-L disintegrin domain was specifically inhibited by anti-alpha(4) and anti-beta(1) function-blocking mAbs. Furthermore, adhesion of various cell lines to MDC-L correlated with expression of the integrin alpha(4)-subunit. Transfected K562 cells expressing alpha(4)beta(1) adhered to the disintegrin domain in contrast to non-transfected K562 cells. We further investigated the binding of recombinant MDC-L disintegrin domain (rDis-Fc) in solution. The rDis-Fc was found to bind to Jurkat cells in solution in a concentration-dependent and saturable manner. Both adhesion and solution binding of rDis-Fc was inhibited by the alpha(4)beta(1) ligand mimetic CS-1 peptide. Additionally, recognition of the MDC-L disintegrin domain required "activation" of lymphocyte beta(1) integrins. The interaction of MDC-L with alpha(4)beta(1) may potentially regulate metalloprotease function by targeting or sequestering the active protease on the cell surface. These results suggest a potential role for the lymphocyte ADAM, MDC-L, in the interaction of lymphocytes with alpha(4)beta(1)-expressing leukocytes.
Bridges
Lance C
LC
Department of Biochemistry and Molecular Biology, the University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.
Tani
Patricia H
PH
Hanson
Krista R
KR
Roberts
Charles M
CM
Judkins
Matthew B
MB
Bowditch
Ron D
RD
D051722:ADAM Proteins; D000595:Amino Acid Sequence; D001665:Binding Sites; D002448:Cell Adhesion; D019483:Disintegrins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D039041:Integrin alpha4beta1; D016023:Integrins / Q000378:metabolism*; D019169:Jurkat Cells; D020014:K562 Cells; D007700:Kinetics; D008024:Ligands; D008214:Lymphocytes / Q000201:enzymology; D016399:Lymphoma, T-Cell; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
D019483:Disintegrins; D039041:Integrin alpha4beta1; D016023:Integrins; D008024:Ligands; D016201:Receptors, Lymphocyte Homing; D051722:ADAM Proteins; C410224:ADAM28 protein, human; D008666:Metalloendopeptidases