T. Itai et al., Processing of tumor necrosis factor by the membrane-bound TNF-alpha-converting enzyme, but not its truncated soluble form, EUR J BIOCH, 268(7), 2001, pp. 2074-2082
Tumour necrosis factor (TNF)-alpha -converting enzyme (TACE) is a membrane
protein belonging to the ADAM (a disintegrin and metalloproteinase) family
that cleaves various membrane proteins, including the preform of TNF-alpha.
In this study, we constructed expression vectors for the membrane-bound fu
ll-length TACE (mTACE) and its truncated soluble form (sTACE). When a human
TNF-alpha expression vector was introduced into human 293 cells, processin
g of TNF-alpha to its mature form was enhanced by coexpressing mTACE, and t
his processing was inhibited by a metalloproteinase inhibitor. On the other
hand, coexpression of sTACE had no effect on the processing of TNF-alpha,
although the culture medium of sTACE-transfected cells could cleave a pepti
de containing the TNF-alpha cleavage site. Fas ligand (FasL)-transfected 29
3 cells released a considerable amount of soluble FasL, and coexpression of
neither mTACE nor sTACE enhanced this shedding. Immunoprecipitation and We
stern blotting analysis with cells that were cotransfected with TACE and TN
F-alpha indicated that both mTACE and sTACE could interact with the proform
of TNF-alpha. In the same assay, neither mTACE nor sTACE interacted with F
asL. The catalytic domain-lacking TACE mutant, which could also interact TN
F-alpha, showed a dominant negative effect on not only TNF-alpha secretion
but also FasL secretion. These results suggest that binding of the membrane
-anchored but not the soluble form of TACE to TNF-alpha results in efficien
t ectodomain shedding, and that FasL secretase is a metalloproteinase simil
ar, but not identical, to TACE.