CONCANAVALIN-A DIRECTLY STIMULATES BONE-RESORBING ACTIVITY OF OSTEOCLASTS AND THEIR GENE-EXPRESSION OF CATHEPSIN K OC-2/

Concanavalin A (Con A), a plant lectin that recognizes cell-surface gl ycoproteins, up-regulates osteoclastic bone-resorbing activity of cult ured isolated rabbit pure osteoclasts as well as unfractionated bone c ells. The effect of Con A was blocked by a-methyl mannopyranoside. Sev eral Con A-binding proteins were detected in the plasma membranes from osteoclasts. Furthermore, Con A increased the levels of transcripts o f cathepsin K/OC-2, one of the proteases responsible for osteoclastic bone-resorbing activity. These results indicate that Con A directly en hances the function of osteoclasts by the association with surface gly coproteins of osteoclasts. (C) 1997 Academic Press.