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Galectin-3 surface expression on human adult chondrocytes: a potential substrate for collagenase-3
  1. M Guévremont1,
  2. J Martel-Pelletier1,
  3. C Boileau1,
  4. F-T Liu2,
  5. M Richard3,
  6. J-C Fernandes1,
  7. J-P Pelletier1,
  8. P Reboul1
  1. 1Unité de Recherche en Arthrose, Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Montréal, Québec, Canada
  2. 2Department of Dermatology, Sacramento, University of California-Davis, California, USA
  3. 3Département de Biochimie, Faculté de Médecine Lyon-Sud, Lyon, France
  1. Correspondence to:
    Dr P Reboul
    Osteoarthritis Research Unit, CR-CHUM, Y2604, 1560 Sherbrooke Street East, Montreal, Quebec, Canada H2L 4M1; pascal.reboulumontreal.ca

Abstract

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.

  • galectin-3
  • osteoarthritis
  • chondrocytes
  • collagenase-3
  • integrin-β1
  • 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
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