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

J Biol Chem. 2009 Nov 13;284(46):31764-75. doi: 10.1074/jbc.M109.038547. Epub 2009 Sep 17.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Blotting, Western
  • Cell Adhesion*
  • Cell Membrane / metabolism*
  • Cells, Cultured
  • Chlorocebus aethiops
  • Circular Dichroism
  • Epidermal Cells
  • Epidermis / metabolism
  • Fibroblasts / metabolism
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Humans
  • Immunoenzyme Techniques
  • Immunoprecipitation
  • Keratinocytes / metabolism
  • Laminin / metabolism*
  • Molecular Sequence Data
  • PC12 Cells
  • Phosphorylation
  • Protein Kinase C-delta / metabolism*
  • Protein Structure, Tertiary
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Homology, Amino Acid
  • Syndecan-1 / genetics
  • Syndecan-1 / metabolism*

Substances

  • Laminin
  • RNA, Messenger
  • Syndecan-1
  • laminin alpha 2
  • Protein Kinase C-delta