Laminin-1 and laminin-2 G-domain synthetic peptides bind syndecan-1 and are involved in acinar formation of a human submandibular gland cell line.
The culture of human submandibular gland (HSG) cells on laminin-1 induces acinar differentiation. We identified a site on laminin involved in acinar differentiation using synthetic peptides derived from the C-terminal G-domain of the laminin alpha1 and alpha2 chains. The alpha1 chain peptide AG73 (RKRLQVQLSIRT) decreases the size of acini formed on laminin-1. Cells cultured with either AG73 or the homologous alpha2 chain peptide MG73 (KNRLTIELEVRT) form structures that appear acinar-like, but the cell nuclei are not polarized to the basal surface and no lumen formation occurs, indicating that additional sites on laminin are required for complete differentiation. The G-domain of laminin-1 contains both integrin and heparin binding sites, and anti-beta1-integrin antibodies disrupt acinar formation. Cell adhesion to the peptides and to E3, an elastase digest fragment of laminin-1 containing AG73, is specific, since other laminin peptides or EDTA do not compete the binding. Heparin and heparan sulfate decrease cell adhesion to AG73 and MG73 but anti-beta1-integrin antibodies have no effect. Treating the cell surface with heparitinase inhibits adhesion to both AG73 and MG73. We isolated cell surface ligands using both peptide affinity chromatography and laminin-1 affinity chromatography. Treating the material bound to the affinity columns with heparitinase and chondroitinase enriches for a core protein identified as syndecan-1 by Western blot analysis, thus identifying a syndecan-1 binding site in the globular domain of laminin-1 and laminin-2. In summary, multiple interactions between laminin and HSG cells contribute to acinar differentiation, involving both beta1-integrins and syndecan-1.
Hoffman
M P
MP
Craniofacial Developmental Biology and Regeneration Branch, NIDR, National Institutes of Health, Bethesda, Maryland 20892-4370, USA.
Nomizu
M
M
Roque
E
E
Lee
S
S
Jung
D W
DW
Yamada
Y
Y
Kleinman
H K
HK
D000595:Amino Acid Sequence; D015153:Blotting, Western; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects; D002846:Chromatography, Affinity; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007536:Isomerism; D007797:Laminin / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism*; D011133:Polysaccharide-Lyases / Q000494:pharmacology; D011485:Protein Binding; D011509:Proteoglycans / Q000378:metabolism*; D013363:Submandibular Gland / Q000166:cytology / Q000378:metabolism*; D053668:Syndecan-1; D053667:Syndecans
D019012:Integrin beta1; D007797:Laminin; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D011509:Proteoglycans; C508241:SDC1 protein, human; D053668:Syndecan-1; D053667:Syndecans; D011133:Polysaccharide-Lyases; C021349:heparitinsulfate lyase