Biomedical subjects

Lance C Bridges

Publications and source records attributed to Lance C Bridges.

5 recordsLinked to original sources

PubMed2005

Selective modulation of integrin-mediated cell migration by distinct ADAM family members.

A disintegrin and a metalloprotease (ADAM) family members have been implicated in many biological processes. Although it is recognized that recombinant ADAM disintegrin domains can interact with integrins, little is known about ADAM-integrin interactions in cellular context. Here, we tested whether ADAMs can selectively regulate integrin-mediated cell migration. ADAMs were expressed in Chinese hamster ovary cells that express defined integrins (alpha4beta1, alpha5beta1, or both), and cell migration on full-length fibronectin or on its alpha4beta1 or alpha5beta1 binding fragments was studied. We found that ADAMs inhibit integrin-mediated cell migration in patterns dictated by the integrin binding profiles of their isolated disintegrin domains. ADAM12 inhibited cell migration mediated by the alpha4beta1 but not the alpha5beta1 integrin. ADAM17 had the reciprocal effect; it inhibited alpha5beta1- but not alpha4beta1-mediated cell migration. ADAM19 and ADAM33 inhibited migration mediated by both alpha4beta1 and alpha5beta1 integrins. A point mutation in the ADAM12 disintegrin loop partially reduced the inhibitory effect of ADAM12 on cell migration on the alpha4beta1 binding fragment of fibronectin, whereas mutations that block metalloprotease activity had no effect. Our results indicate that distinct ADAMs can modulate cell migration mediated by specific integrins in a pattern dictated, at least in part, by their disintegrin domains.

ADAM Proteins↗

PubMed2005

ADAM disintegrin-like domain recognition by the lymphocyte integrins alpha4beta1 and alpha4beta7.

The ADAM (a disintegrin and metalloprotease) family of proteins possess both proteolytic and adhesive domains. We have established previously that the disintegrin domain of ADAM28, an ADAM expressed by human lymphocytes, is recognized by the integrin alpha4beta1. The present study characterizes the integrin binding properties of the disintegrin-like domains of human ADAM7, ADAM28 and ADAM33 with the integrins alpha4beta1, alpha4beta7 and alpha9beta1. Cell-adhesion assays demonstrated that, similar to ADAM28, the ADAM7 disintegrin domain supported alpha4beta1-dependent Jurkat cell adhesion, whereas the ADAM33 disintegrin domain did not. The lymphocyte integrin alpha4beta7 was also found to recognize both disintegrin domains of ADAM7 and ADAM28, but not of ADAM33. This is the first demonstration that mammalian disintegrins are capable of interacting with alpha4beta7. All three disintegrin domains supported alpha9beta1-dependent cell adhesion. Recognition by both alpha4beta1 and alpha4beta7 of ADAM7 and ADAM28 was activation-dependent, requiring either the presence of Mn2+ or an activating monoclonal antibody for cell attachment. Charge-to-alanine mutagenesis experiments revealed that the same residues within an individual ADAM disintegrin domain function in recognizing multiple integrins. However, the residues within a specific region of each ADAM disintegrin-like domain required for integrin binding were distinct. These results establish that ADAM7 and ADAM28 are recognized by the leucocyte integrins alpha4beta1, alpha4beta7 and alpha9beta1. ADAM33 exclusively supported only alpha9beta1-dependent adhesion.

ADAM Proteins↗

PubMed2005

ADAM-Integrin Interactions: potential integrin regulated ectodomain shedding activity.

ADAMs (a disintegrin and metalloprotease) are a family of cell surface proteins related to the Class III snake venom metalloproteases (SVMP). ADAMs are members of the Metazincin family which includes the matrix matalloproteases and the ADAMTS proteins. Unlike their snake venom relatives, ADAMs are expressed as transmembrane cell surface proteins. The domain structure of ADAMs suggests that these proteins posses both proteolytic and adhesive functions. Several members of the ADAM protein family have been shown to be involved in ectodomain shedding of many important cell surface proteins resulting in the release of biologically active soluble factors. The carboxyl-terminal domains, especially the disintegrin-like domain of ADAMs, have been demonstrated to support cell adhesion. The disintegrin-like domains of many ADAMs are capable of acting as integrin ligands. Integrins known to interact with ADAM disintegrin-like domains include alpha4beta1, alpha4beta7, alpha5beta1, alpha6beta1, alpha9beta1, alphavbeta3, and alphavbeta5. This integrin mediated interaction of the disintegrin-like domains with the cell surface suggests that ADAMs may function as cellular counter receptors. In this review we discuss the individual functions ascribed to members of the ADAM family especially those related to integrin interactions and the potential for integrin mediated regulation of ectodomain shedding.

Animals↗

PubMed2003

Integrin alpha4beta1-dependent adhesion to ADAM 28 (MDC-L) requires an extended surface of the disintegrin domain.

ADAMs (a disintegrin and metalloprotease) are a family of proteins that possess functional adhesive and proteolytic domains. ADAM 28 (MDC-L) is expressed by human lymphocytes and contains a disintegrin-like domain that serves as a ligand for the leukocyte integrin, alpha4beta1. To elucidate which residues comprise the alpha4beta1 binding site in the ADAM 28 disintegrin domain, a charge-to-alanine mutagenesis strategy was utilized. Each alanine substitution mutant was evaluated and compared to the native sequence for its ability to support cell adhesion of the T-lymphoma cell line, Jurkat. This approach identified ADAM 28 residues Lys(437), Lys(442), Lys(455), Lys(459), Lys(460), Lys(469), and Glu(476) as being essential for alpha4beta1-dependent cell adhesion. The epitope for a function-blocking monoclonal antibody, Dis 1-1, was localized to the N-terminal end of the ADAM 28 disintegrin domain using these same charge-to-alanine mutants. Three distinct molecular models based upon the known structures of snake venom disintegrins suggested that residues contributing to alpha4beta1 recognition are aligned on one face of the domain. This study demonstrates that residues located outside of the disintegrin loop participate in integrin recognition of mammalian disintegrins.

ADAM Proteins↗

PubMed2001

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.

ADAM Proteins↗