The Cysteine-Rich Domain of Human Adam 12 Supports Cell Adhesion through Syndecans and Triggers Signaling Events That Lead to β1 Integrin–Dependent Cell Spreading

Abstract

The ADAMs (a disintegrin and metalloprotease) family of proteins is involved in a variety of cellular interactions, including cell adhesion and ecto- domain shedding. Here we show that ADAM 12 binds to cell surface syndecans. Three forms of recombinant ADAM 12 were used in these experiments: the cys-teine-rich domain made in Escherichia coli (rADAM 12-cys), the disintegrin-like and cysteine-rich domain made in insect cells (rADAM 12-DC), and full-length human ADAM 12-S tagged with green fluorescent protein made in mammalian cells (rADAM 12-GFP). Mesenchymal cells specifically and in a dose-dependent manner attach to ADAM 12 via members of the syndecan family. After binding to syndecans, mesenchymal cells spread and form focal adhesions and actin stress fibers. Integrin β1 was responsible for cell spreading because function-blocking monoclonal antibodies completely inhibited cell spreading, and chondroblasts lacking β1 integrin attached but did not spread. These data suggest that mesenchymal cells use syndecans as the initial receptor for the ADAM 12 cysteine-rich domain–mediated cell adhesion, and then the β1 integrin to induce cell spreading. Interestingly, carcinoma cells attached but did not spread on ADAM 12. However, spreading could be efficiently induced by the addition of either 1 mM Mn2+ or the β1 integrin–activating monoclonal antibody 12G10, suggesting that in these carcinoma cells, the ADAM 12–syndecan complex fails to modulate the function of β1 integrin.

Expression of a disintegrin and metalloprotease (ADAM and ADAMTS) enzymes in human non-small-cell lung carcinomas (NSCLC)

“…The fact that invasive cell lines (BZR and BZRT33) expressed huge amounts of ADAM-12 when compared to cell lines derived from normal epithelium (BEAS-2B and 16HBE) suggests that ADAM-12 may play a role in the cascade of events leading to the invasive phenotype. As demonstrated recently, ADAM-12 could play an important role in cell adhesion (Zolkiewska, 1999;Iba et al, 2000) and, therefore, its increased expression in lung cancer cells could be mandatory for tumour cell migration and invasion through a control of cell -matrix interactions. In addition, ADAM-12 could be of particular importance in the processes leading to cell proliferation since it sheds the soluble heparinbinding epidermal growth factor (Asakura et al, 2002).…”

Expression profiling of metalloproteinases and tissue inhibitors of metalloproteinases in normal and degenerate human achilles tendon

“…ADAM-12 has been demonstrated to cleave insulin-like growth factor binding proteins 3 and 5, pro-heparin-binding epidermal growth factor, and the ECM components gelatin, type IV collagen, and fibronectin (43)(44)(45)(46), and may therefore be significant in painful tendinopathy, both as a regulator of cytokine activity and as a mediator of ECM degradation. ADAM-12 is also reported to support cell attachment and influence cell spreading and migration (47)(48)(49). Rounded cells are observed more frequently in pathologic tendons (50) and it is possible that ADAM-12 may influence this morphologic feature of the cells.…”

Emerging roles of ADAM and ADAMTS metalloproteinases in cancer

“…Adhesion and migration of cells might be regulated by the disintegrin or cystein-rich domains whose importance has been evidenced by different studies [12,[61][62][63].…”