Relaxin induces collagenase-1 and stromelysin-1 in fibrocartilaginous explants from temporomandibular joint. Disc hemisections were exposed for 48 hours to basal control medium (Ct), β-estradiol (Es, 20 ng/ml), or relaxin (R, 0.1 ng/ml) or to β-estradiol plus relaxin (Es+R). Conditioned medium, standardized by tissue weight, was subjected to SDS–polyacrylamide-gel electrophoresis and transferred to membranes for western immunoblots for collagenase-1 (a) or stromelysin-1 (d) or assayed in gels containing gelatin (b) or α-casein (e). Images of the substrate gels were digitized, and the 53/58 kDa and 43 kDa gelatinase activities (collagenase and active collagenase, respectively) (c) and the 51/54 kDa caseinolytic activity (stromelysin) (f) were quantified by videodensitometry. The samples used in lane 6 of panels (b) and (e) are positive controls for collagenase-1 and stromelysin-1. P, gels incubated in buffer containing the metalloproteinase inhibitor 1,10-phenanthroline; Cl-1, collagenase-1; ACl-1, active collagenase-1; Sl-1, stromelysin-1; α-Cl, anti-collagenase-1 antibody; α-Sl, anti-stromelysin-1 antibody. * P < 0.05.
Naqvi et al. Arthritis Res Ther 2005 7:R1-R11 doi:10.1186/ar1451