Functional Classification of ADAMs Based on a Conserved Motif for Binding to Integrin α9β1

Abstract

ADAMs (a disintegrin and metalloproteases) are members of the metzincin superfamily of metalloproteases. Among integrins binding to disintegrin domains of ADAMs are ␣ 9 ␤ 1 and ␣ v ␤ 3 , and they bind in an RGDindependent and an RGD-dependent manner, respectively. Human ADAM15 is the only ADAM with the RGD motif in the disintegrin domain. Thus, both integrin ␣ 9 ␤ 1 and ␣ v ␤ 3 recognize the ADAM15 disintegrin domain. We determined how these integrins recognize the ADAM15 disintegrin domain by mutational analysis. We found that the Arg 481 and the Asp-Leu-Pro-Glu-Phe residues (residues 488 -492) were critical for ␣ 9 ␤ 1 binding, but the RGD motif (residues 484 -486) was not. In contrast, the RGD motif was critical for ␣ v ␤ 3 binding, but the other residues flanking the RGD motif were not. As the RX 6 DLPEF ␣ 9 ␤ 1 recognition motif (residues 481-492) is conserved among ADAMs, except for ADAM10 and 17, we hypothesized that ␣ 9 ␤ 1 may recognize disintegrin domains in all ADAMs except ADAM10 and 17. Indeed we found that ␣ 9 ␤ 1 bound avidly to the disintegrin domains of ADAM1, 2, 3, and 9 but not to the disintegrin domains of ADAM10 and 17. As several ADAMs have been implicated in sperm-oocyte interaction, we tested whether the functional classification of ADAMs, based on specificity for integrin ␣ 9 ␤ 1 , applies to sperm-egg binding. We found that the ADAM2 and 15 disintegrin domains bound to oocytes, but the ADAM17 disintegrin domain did not. Furthermore, the ADAM2 and 15 disintegrin domains effectively blocked binding of sperm to oocytes, but the ADAM17 disintegrin domain did not. These results suggest that oocytes and ␣ 9 ␤ 1 have similar binding specificities for ADAMs and that ␣ 9 ␤ 1 , or a receptor with similar specificity, may be involved in sperm-egg interaction during fertilization. As ␣ 9 ␤ 1 is a receptor for many ADAM disintegrins and ␣ 9 ␤ 1 and ADAMs are widely expressed, ␣ 9 ␤ 1 -ADAM interaction may be of a broad biological importance. ADAMs1 (a disintegrin and metalloproteases) or MDC (metalloprotease/disintegrin/cysteine-rich) proteins are a family of transmembrane glycoproteins of more than 30 members (see www.people.virginia.edu/ϳjag6n/Table_of_the_ADAMs.html and www.gene.ucl.ac.uk/nomenclature/genefamily/metallo. html). ADAMs have a prodomain, a metalloprotease domain, a disintegrin domain, a cysteine-rich region, an EGF-like domain, a transmembrane domain, and a cytoplasmic tail (1-3). Several ADAMs are involved in crucial biological processes such as fertilization (ADAM1, 2, and 3) (4 -6) and muscle cell differentiation (meltrin-␣, ADAM12) (7, 8). Most, but not all, ADAMs have a catalytically active metalloprotease domain, which processes several biologically important cell surface proteins including tumor necrosis factor-␣ (tumor necrosis factor converting enzyme (TACE), ADAM17) (for reviews, see Refs. 9 and 10), Alzheimer protein precursor (ADAM10 and 17) (11, 12), Delta (ADAM10) (9, 13, 14), and heparin-binding EGF (ADAM9) (15).The ADAM disintegrin domains are homologous to snake ven...

ADAM12/Syndecan-4 Signaling Promotes β1Integrin-dependent Cell Spreading through Protein Kinase Cα and RhoA

“…It is up-regulated in carcinoma cells (16) and may therefore dramatically influence cell-cell interactions as well as the local microenvironment at the interface between the tumor cells and the surrounding stroma. To determine the function of ADAM12, we and others have performed cell attachment assays (11,12,16,17,59). We found that rADAM12-cys is a substrate for cell attachment using syndecan(s) as the primary receptor (16,17).…”

Cellular integrins function as entry receptors for human cytomegalovirus via a highly conserved disintegrin-like domain

“…Because all viruses known to use integrins as entry receptors have been shown to do so by ECM protein mimicry, we inspected all HCMV structural glycoproteins for the integrin-binding sequences LDV, DGE, RGD, NGR, RRETAWA, REDV, SDGR, YIGSR, YIGSE, RGES, RSGIY, RSGD, DRDE, and SRYD by using DNASTAR software (DNASTAR, Madison, WI). We found that all HCMV glycoproteins lack ECM-derived integrinbinding sequences, but the gB protein does contain a sequence very similar to the RX 6-8 DLXXF found in the ADAM family of proteins, which we have termed disintegrin-like (18,19). The gB sequences of 44 HCMV clinical isolates and two laboratory strains were analyzed for the presence of the disintegrin-like domain.…”

“…ADAM members are multidomain proteins that can modulate a variety of cell-cell and cell-ECM interactions with specific (primarily) ␤1 integrin heterodimers (18). From the 30 known members of the ADAM family, a disintegrin loop domain consensus and minimum integrin recognition motif has been identified (RX 5-7 DLXXF͞L) (19).…”

Kaposi's Sarcoma-associated Herpesvirus Activation of Vascular Endothelial Growth Factor Receptor 3 Alters Endothelial Function and Enhances Infection

“…The RGD amino acids constitute the minimal region of several extracellular matrix proteins required for interaction with certain cell surface integrins. The RGD motif is the most common integrin recognition motif, but other RGD-independent integrin recognition motifs have also been reported (9,10). Recently, a gB disintegrin-like domain has been identified in the envelope glycoprotein B of the human cytomegalovirus by analysis of its sequence (11).…”