Normal human keratinocytes bind to the alpha3LG4/5 domain of unprocessed laminin-5 through the receptor syndecan-1.
Basal keratinocytes of the epidermis adhere to their underlying basement membrane through a specific interaction with laminin-5, which is composed by the association of alpha3, beta3, and gamma2 chains. Laminin-5 has the ability to induce either stable cell adhesion or migration depending on specific processing of different parts of the molecule. One event results in the cleavage of the carboxyl-terminal globular domains 4 and 5 (LG4/5) of the alpha3 chain. In this study, we recombinantly expressed the human alpha3LG4/5 fragment in mammalian cells, and we show that this fragment induces adhesion of normal human keratinocytes and fibrosarcoma-derived HT1080 cells in a heparan- and chondroitin sulfate-dependent manner. Immunoprecipitation experiments with Na2 35SO4-labeled keratinocyte and HT1080 cell lysates as well as immunoblotting experiments revealed that the major proteoglycan receptor for the alpha3LG4/5 fragment is syndecan-1. Syndecan-4 from keratinocytes also bound to alpha3LG4/5. Furthermore we could show for the first time that unprocessed laminin-5 specifically binds syndecan-1, while processed laminin-5 does not. These results demonstrate that the LG4/5 modules within unprocessed laminin-5 permit its cell binding activity through heparan and chondroitin sulfate chains of syndecan-1 and reinforce previous data suggesting specific properties for the precursor molecule.
Okamoto
Osamu
O
Institut de Biologie et Chimie des Protéines, Unité Mixte de Recherche 5086, Institut Fédératif de Recherche 128 BioSciences Lyon-Gerland, 7 passage du Vercors, 69367 Lyon, France.
Bachy
Sophie
S
Odenthal
Uwe
U
Bernaud
Janine
J
Rigal
Dominique
D
Lortat-Jacob
Hugues
H
Smyth
Neil
N
Rousselle
Patricia
P
D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D019765:Chondroitin ABC Lyase / Q000378:metabolism; D002809:Chondroitin Sulfates / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D006224:Cricetinae; D004622:Embryo, Mammalian; D005354:Fibrosarcoma; D015870:Gene Expression; D006497:Heparan Sulfate / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007163:Immunosorbent Techniques; D015603:Keratinocytes / Q000378:metabolism*; D007668:Kidney; D007797:Laminin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D011133:Polysaccharide-Lyases / Q000378:metabolism; D011509:Proteoglycans / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins; D013431:Sulfates; D013462:Sulfur Radioisotopes; D053668:Syndecan-1; D053667:Syndecans; D014162:Transfection; D014407:Tumor Cells, Cultured; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D019765:Chondroitin ABC Lyase; D002809:Chondroitin Sulfates; D006497:Heparan Sulfate; D007797:Laminin; D008562:Membrane Glycoproteins; D011133:Polysaccharide-Lyases; D011509:Proteoglycans; D011994:Recombinant Proteins; D013431:Sulfates; D013462:Sulfur Radioisotopes; D053668:Syndecan-1; D053667:Syndecans; D000097794:Kalinin; C508241:SDC1 protein, human; C012036:sodium sulfate; C095567:laminin alpha 3; C021349:heparitinsulfate lyase