title: A biologically active sequence of the laminin alpha2 large globular 1 domain promotes cell adhesion through syndecan-1 by inducing phosphorylation and membrane localization of protein kinase Cdelta.
abstract: Laminin-2 promotes basement membrane assembly and peripheral myelinogenesis; however, a receptor-binding motif within laminin-2 and the downstream signaling pathways for motif-mediated cell adhesion have not been fully established. The human laminin-2 alpha2 chain cDNAs cloned from human keratinocytes and fibroblasts correspond to the laminin alpha2 chain variant sequence from the human brain. Individually expressed recombinant large globular (LG) 1 protein promotes cell adhesion and has heparin binding activities. Studies with synthetic peptides delineate the DLTIDDSYWYRI motif (Ln2-P3) within the LG1 as a major site for both heparin and cell binding. Cell adhesion to LG1 and Ln2-P3 is inhibited by treatment of heparitinase I and chondroitinase ABC. Syndecan-1 from PC12 cells binds to LG1 and Ln2-P3 and colocalizes with both molecules. Suppression of syndecan-1 with RNA interference inhibits cell adhesion to LG1 and Ln2-P3. The binding of syndecan-1 with LG1 and Ln2-P3 induces the recruitment of protein kinase Cdelta (PKCdelta) into the membrane and stimulates its tyrosine phosphorylation. A decrease in PKCdelta activity significantly reduces cell adhesion to LG1 and Ln2-P3. Taken together, these results indicate that the Ln2-P3 motif and LG1 domain, containing the motif, within the human laminin-2 alpha2 chain are major ligands for syndecan-1, which mediates cell adhesion through the PKCdelta signaling pathway.
authors.affiliation: Department of Oral Biochemistry and Program of Craniomaxillofacial Reconstruction Science, Dental Research Institute, Intellectual Biointerface Engineering Center, BK21 CLS, Seoul National University School of Dentistry, Seoul 110-749, Korea.
authors.forename: Sung Youn
authors.initials: SY
authors.lastname: Jung
authors.forename: Jin-Man
authors.initials: JM
authors.lastname: Kim
authors.forename: Hyun Ki
authors.initials: HK
authors.lastname: Kang
authors.forename: Da Hyun
authors.initials: DH
authors.lastname: Jang
authors.forename: Byung-Moo
authors.initials: BM
authors.lastname: Min
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D002942:Circular Dichroism; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D015603:Keratinocytes / Q000378:metabolism; D007797:Laminin / Q000378:metabolism*; D008969:Molecular Sequence Data; D016716:PC12 Cells; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D053668:Syndecan-1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D007797:Laminin; D012333:RNA, Messenger; D053668:Syndecan-1; C102645:laminin alpha 2; D051745:Protein Kinase C-delta