Identification of Homologous Biologically Active Sites on the N-Terminal Domain of Laminin Alpha Chains

• Published in: Biochemistry (Easton) 2001-12, Vol.40 (50), p.15310-15317
• Main Authors: Nomizu, Motoyoshi, Yokoyama, Fumiharu, Suzuki, Nobuharu, Okazaki, Ikuko, Nishi, Norio, Ponce, M. Lourdes, Kleinman, Hynda K, Yamamoto, Yoko, Nakagawa, Shinsaku, Mayumi, Tadanori
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Binding Sites; Cell Adhesion - drug effects; Cell Line; Edetic Acid - pharmacology; Heparin - pharmacology; Humans; In Vitro Techniques; Laminin - chemistry; Laminin - genetics; Laminin - metabolism; Laminin - pharmacology; Lung Neoplasms - secondary; Melanoma, Experimental - secondary; Mice; Molecular Sequence Data; Neovascularization, Physiologic - drug effects; Peptide Fragments - pharmacology; Protein Structure, Tertiary; Protein Subunits; Sequence Homology, Amino Acid
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi011552c

Laminin, a multifunctional glycoprotein of the basement membrane, consists of three different subunits, α, β, and γ chains. To date, five different α chains have been identified. N-terminal domain VI in the α1 chain has various biological activities. Here we screened biologically active sequences on domain VI of the laminin α2, α3, and α5 chains using a large number of overlapping peptides. HT-1080 human fibrosarcoma cell attachment to the peptides was evaluated using peptide-coated plastic plates and peptide-conjugated Sepharose beads. We identified four cell adhesive sequences from laminin α2 chain domain VI, two sequences from the α3 chain, and two sequences from the laminin α5 chain. Sequences homologous to A13 (RQVFQVAYIIIKA, α1 chain 121−133) on all the α chains (FQIAYVIVKA, α2 chain 130−139; GQLFHVAYILIKF, α3 chain 96−108; FHVAYVLIKA, α5 chain 74−83) showed strong cell attachment activity. A5−16 (LENGEIVVSLVNGR, α5 chain 147−160) showed the strongest cell attachment activity in the plate assay, and the homologous peptide in the α3 chain promoted similar strong cell attachment activity. A5−16 and its homologous peptide in the α2 chain promoted moderate cell attachment, while the homologous peptide to A5−16 in the α1 chain did not show activity. A2−7 (SPSIKNGVEYHYV, α2 chain 108−120) showed cell attachment activity only in the plate assay, but homologous sequences in the α1, α3, and α5 chains did not promote activity. A2−7 promoted endothelial cell sprouting from aortic rings in vitro and melanoma colonization to murine lungs in vivo. However, none of the homologous peptides of A2−7 promoted experimental pulmonary metastasis by B16−BL6 melanoma cells. These results indicate that there are chain-specific active sites in domain VI of the laminin α chains, some of which contain conserved activities.