Galectin-3 surface expression on human adult chondrocytes: a potential substrate for collagenase-3
- M Guévremont1,
- J Martel-Pelletier1,
- C Boileau1,
- F-T Liu2,
- M Richard3,
- J-C Fernandes1,
- J-P Pelletier1,
- P Reboul1
- 1Unité de Recherche en Arthrose, Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Montréal, Québec, Canada
- 2Department of Dermatology, Sacramento, University of California-Davis, California, USA
- 3Département de Biochimie, Faculté de Médecine Lyon-Sud, Lyon, France
- Correspondence to:
Dr P Reboul
Osteoarthritis Research Unit, CR-CHUM, Y2604, 1560 Sherbrooke Street East, Montreal, Quebec, Canada H2L 4M1;
- Accepted 17 August 2003
Background: Galectin-3 is a lectin detected in mature and early hypertrophic chondrocytes; osteoarthritic (OA) chondrocytes can re-express hypertrophic markers.
Objective: To investigate the synthesis and subcellular localisation of galectin-3 in adult chondrocytes as well as the possibility of cleavage of galectin-3 by collagenase-1 and -3.
Methods: Galectin-3 was assessed by immunohistochemistry and real time polymerase chain reaction (PCR) in normal and OA cartilage. Its localisation was investigated by subcellular fractionation, immunocytology, and flow cytometry. Proteolysis of galectin-3 by collagenase-1 and -3 was determined by in vitro assay.
Results: Galectin-3 expression was increased 2.4-fold as measured by reverse transcriptase (RT)-PCR (p<0.05, n = 5) and threefold by immunohistochemistry (p<0.003 n = 6) in OA cartilage compared with normal cartilage. In adult chondrocytes, galectin-3 was found in the cytosol and membrane enriched fractions. Both immunocytology and flow cytometry confirmed the presence of galectin-3 at the surface of chondrocytes. A strong correlation was found between integrin-β1 and galectin-3 expression at the surface of chondrocytes. Moreover, collagenase-3 cleaved galectin-3 with a higher activity than collagenase-1. The proteolysed sites generated were identical to those produced by gelatinases A and B.
Conclusion: Galectin-3 may play a part in OA, having two roles, one intracellular and not yet identified, and another at the cell surface, possibly related to the interaction of chondrocytes and the cartilage matrix.
- 7-AAD, 7-aminoactinomycin D
- ECM, extracellular matrix
- MMP, matrix metalloproteinase
- OA, osteoarthritis/osteoarthritic
- PBS, phosphate buffered saline
- PCR, polymerase chain reaction
- RT-PCR, reverse transcriptase-polymerase chain reaction
- SDS-PAGE, sodium dodecyl sulphate-polyacrylamide gel electrophoresis