3.1 Papers
3.1.6 Chronological list
3.1.6.55 Patel, I.R., Attur, M.G., Patel, R.N., Stuchin, S.A., Abagyan, R.A., Abramson, S.B., and Amin, A.R. (1998). TNF-a convertase enzyme from human arthritis-affected cartilage: Isolation of cDNA by differential display, expression of the active enzyme, and regulation of TNF-a. J. of Immunology, 160, 4570-4579
A snake venom-like protease isolated by a differential display screen between normal and osteoarthritis (OA)-affected cartilage
(designated as cSVP) has a cDNA sequence identical to TNF-alpha convertase enzyme (TACE). TACE shows the presence of an
unknown prodomain, a cysteine switch, a catalytic domain, a zinc binding region, a disintegrin region, an EGF-like domain, a
transmembrane domain, and a unique cytoplasmic region. A TACE construct harboring the signal + prodomain + catalytic region
(TACE-SPCdeltaDETCy), expressed in baculovirus could cleave preferentially (approximately 12-fold) the TNF-specific peptide over
the matrix metalloproteases peptide in vitro. This recombinant protein also cleaved the natural substrate GST-ProTNF-alpha to
TNF-alpha (17 kDa) in vitro. The mRNA for TACE, which is broadly distributed and differentially expressed in a variety of human
tissues, is up-regulated in arthritis-affected cartilage, but not normal cartilage. OA-affected cartilage also expressed TNF-alpha mRNA
that was not detected in normal cartilage. The OA-affected cartilage (in explant assays) spontaneously released TNF-alpha and IL-8 in
ex vivo conditions. Addition of TNF-alphaR fused to IgG Fc fragment (TNF-alphaR:Fc) in the presence or absence of soluble IL-1R
(with which it acted additively) significantly attenuated the spontaneous/autocrine release of articular IL-8 in this assay. These
experiments demonstrate a functional paracrine/autocrine role of TNF-alpha in OA-affected cartilage that may depend, in part, on
up-regulated levels of chondrocyte-derived TACE.