title: The leucine-rich repeat protein PRELP binds fibroblast cell-surface proteoglycans and enhances focal adhesion formation.
abstract: PRELP (proline/arginine-rich end leucine-rich repeat protein) is a member of the leucine-rich repeat (LRR) family of extracellular matrix proteins in connective tissue. In contrast with other members of the family, the N-terminal domain of PRELP has a high content of proline and positively charged amino acids. This domain has previously been shown to bind chondrocytes and to inhibit osteoclast differentiation. In the present study, we show that PRELP mediates cell adhesion by binding to cell-surface glycosaminoglycans (GAGs). Thus, rat skin fibroblasts (RSFs) bound to full-length PRELP and to the N-terminal part of PRELP alone, but not to truncated PRELP lacking the positively charged N-terminal region. Cell attachment to PRELP was inhibited by addition of soluble heparin or heparan sulfate (HS), by blocking sulfation of the fibroblasts or by treating the cells with a combination of chondroitinase and heparinase. Using affinity chromatography, we identified syndecan-1, syndecan-4 and glypican-1 as cell-surface proteoglycans (PGs) binding to the N-terminal part of PRELP. Finally, we show that the N-terminal domain of PRELP in combination with the integrin-binding domain of fibronectin, but neither of the fragments alone, induced fibroblast focal adhesion formation. These findings provide support for a role of the N-terminal region of PRELP as an important regulator of cell adhesion and behaviour, which may be of importance in pathological conditions.
authors.affiliation: Department of Clinical Sciences Lund, Section for Rheumatology and Molecular Skeletal Biology, Lund University, BMC-C12, SE-221 84 Lund, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Bengtsson
authors.affiliation: Department of Clinical Sciences Lund, Section for Rheumatology and Molecular Skeletal Biology, Lund University, BMC-C12, SE-221 84 Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Lindblom
authors.affiliation: Department of Clinical Sciences Lund, Section for Rheumatology and Molecular Skeletal Biology, Lund University, BMC-C12, SE-221 84 Lund, Sweden.
authors.forename: Viveka
authors.initials: V
authors.lastname: Tillgren
authors.affiliation: Department of Clinical Sciences Lund, Section for Rheumatology and Molecular Skeletal Biology, Lund University, BMC-C12, SE-221 84 Lund, Sweden anders.aspberg@med.lu.se.
authors.forename: Anders
authors.initials: A
authors.lastname: Aspberg
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D022001:Focal Adhesions / Q000235:genetics / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006493:Heparin / Q000235:genetics / Q000378:metabolism; D006497:Heparan Sulfate / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000072417:Protein Domains; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism*; D051381:Rats
chemical_list: D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D006493:Heparin; D006497:Heparan Sulfate; D011509:Proteoglycans; C096382:PRELP protein, human; C490749:Prelp protein, rat
keywords: cell adhesion; focal adhesions; proline/arginine-rich end leucine-rich repeat protein (PRELP); proteoglycans; syndecan