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.
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.
Jung
Sung Youn
SY
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.
Kim
Jin-Man
JM
Kang
Hyun Ki
HK
Jang
Da Hyun
DH
Min
Byung-Moo
BM
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*
D007797:Laminin; D012333:RNA, Messenger; D053668:Syndecan-1; C102645:laminin alpha 2; D051745:Protein Kinase C-delta