Localisation and activity of cathepsins K and B in XXXX osteoclasts.

@entity1641 @entity462 @entity70892 @entity1184 @entity19258 @entity33050 @entity70893
@entity70892 and @entity70893 were immunolocalised in @entity1641 osteoclasts (OC s) present in ex vivo cartilage/subchondral bone samples. Samples were obtained post mortem from the lateral trochlear ridge (LTR) of six @entity1641 and ponies aged between 303 days gestation to 8 months. Strong expression of @entity70892 was detected in OC s, particularly those located at the osteochondral junction, apparently involved in the resorption of calcified cartilage. @entity70892 expression was also detected in @entity1184 chondrocytes and in the endothelial cells of some blood vessels penetrating the @entity1184 zone of cartilage. By contrast, @entity70893 was either absent or present at very low levels in OC s.Osteoclast-like cells (OCL s) were generated in vitro from bone marrow (BM), obtained from the femurs of one @entity1641 and two ponies. High levels of @entity70892 activity but only very low levels of @entity70893 activity were demonstrated in OCL s using fluorogenic substrates for these enzymes. The @entity70892 activity could be blocked by the general @entity462 proteinase inhibitor, @entity19258 , but not by the @entity70893 inhibitor, @entity33050 . The @entity70893 activity was completely blocked by both CA-074Me and E-64. Taken together, these results suggest that @entity70892 is more important than @entity70893 in the osteoclastic resorption of bone and calcified cartilage of developing @entity1641 long bones. Given the apparent importance of @entity70892 in @entity1641 endochondral ossification further investigation into the possibility that abnormal expression of this enzyme is involved in the pathogenesis of @entity1641 developmental orthopaedic disease is warranted.
