Cloning and characterization of ADAMTS11, an aggrecanase from the ADAMTS family

Aggrecan is responsible for the mechanical properties of cartilage. One of the earliest changes observed in arthritis is the depletion of cartilage ag grecan due to increased proteolytic cleavage within the interglobular domai n. Two major sites of cleavage have been identified in this region at Asn(3 41)-Phe(342) and Glu(373)-Ala(374) While several matrix metalloproteinases have been shown to cleave at Asn(341)-Phe(342), an as yet unidentified prot ein termed "aggrecanase" is responsible for cleavage at Glu(373)-Ala(374) a nd is hypothesized to play a pivotal role in cartilage damage. We have iden tified and cloned a novel disintegrin metalloproteinase with thrombospondin motifs that possesses aggrecanase activity, ADAMTS11 (aggrecanase-2), whic h has extensive homology to ADAMTS4 (aggrecanase-1) and the inflammation-as sociated gene ADAMTS1, ADAMTS11 possesses a number of conserved domains tha t have been shown to play a role in integrin binding, cell-cell interaction s, and extracellular matrix binding. We have expressed recombinant human AD AMTS11 in insect cells and shown that it cleaves aggrecan at the Glu(373)-A la(374) site, with the cleavage pattern and inhibitor profile being indisti nguishable from that observed with native aggrecanase, A comparison of the structure and expression patterns of ADAMTS11, ADAMTS4, and ADAMTS1 is also described. Our findings will facilitate the study of the mechanisms of car tilage degradation and provide targets to search for effective inhibitors o f cartilage depletion in arthritic disease.