Identification and characterization of tissue specific active sites in the laminins

点击翻译按钮获取中文摘要

Laminins, heterotrimers composed of α,β, and γ chains, are multifunctional glycoproteins present in basement membranes. Laminins are the most important component of basement membranes during basement membrane assembly in early development. Laminins are involved in various biological activities such as cell adhesion, migration, growth, differentiation, tumor metastasis, and angiogenesis. Fifteen laminin isoforms have been identified and are tissue- and/or developmental stage-specifically expressed. Integrins, dystroglycan, syndecans, and the other several cell surface molecules are cellular receptors for laminins. We prepared various recombinant proteins, comprising the G domains of laminin α1,α3 and α4 chains, and tested their cell attachment activity. Several recombinant proteins showed cell attachment and neurite outgrowth activities. We also synthesized more than 500 overlapping peptides covering the entire G domains and tested their cell attachment activity. More than 20 peptides promoted cell attachment and five peptides inhibited the biological activity mediated by the recombinant proteins. Some of the peptides were found to interact with integrins and syndecans. Additionally, some of the cyclic peptides enhanced the activity. These results suggest that the active sites are involved in the biological functions of the laminin α chain G domains. These active peptides may be useful for defining of the molecular mechanism of laminin-receptor interactions and laminin-mediated cellular signaling pathways. We conjugated the laminin active peptides onto a chitosan membrane. The active laminin peptide-conjugated chitosan membranes enhanced the biological activity and promoted cell adhesion in a cell-type specific manner. We also demonstrated that the peptide-chitosan membrane can deriver cells and is applicable for keratinocyte transferring to wound bed. The peptide-chitosan approach may be a powerful cell transplantation tool for various tissues and organs.