| Autor: |
Morrison, Charlotte J., Butler, Georgina S., Bigg, Heather F., Roberts, Clive R., Soloway, Paul D., Overall, Christopher M. |
| Zdroj: |
Journal of Biological Chemistry; December 2001, Vol. 276 Issue: 50 p47402-47410, 9p |
| Abstrakt: |
The role of membrane-type (MT) 2-matrix metalloproteinase (MMP) in the cellular activation of MMP-2 and the tissue inhibitor of matrix metalloproteinase (TIMP) requirements for this process have not been clearly established. To address these issues a TIMP-2-free cell line derived from a Timp2−/− mouse was transfected for stable cell surface expression of hMT2-MMP. Untransfected cells did not activate endogenous or exogenous TIMP-2-free MMP-2 unless both TIMP-2 and concanavalin A (ConA) were added. Transfected cells expressing hMT2-MMP efficiently activated both endogenous and exogenous MMP-2 (within 4 h) via the 68-kDa intermediate in the absence of TIMP-2 and ConA. In contrast, activation of MMP-2 by Timp2−/− cells expressing recombinant hMT1-MMP occurred more slowly (12 h) and required the addition of 0.3–27 nmTIMP-2. Addition of TIMP-2 or TIMP-4 did not enhance MMP-2 activation by MT2-MMP at any concentration tested; furthermore, activation was inhibited by both TIMPs at concentrations >9 nm, consistent with the similar association rate constants (kon) calculated for the binding of TIMP-4 and TIMP-2 to MT2-MMP (3.56 × 105m−1s−1and 6.52 × 105m−1s−1, respectively). MT2-MMP-mediated activation involved cell surface association of the MMP-2 in a hemopexin carboxyl-terminal domain (C domain)-dependent manner: Exogenous MMP-2 hemopexin C domain blocked activation, and cells expressing hMT2-MMP did not bind or activate a truncated form of MMP-2 lacking the hemopexin C domain. These studies demonstrate the existence of an alternative TIMP-2-independent pathway for MMP-2 activation involving MT2-MMP, which may be important in mediating MMP-2 activation in specific tissues or pathologies where MT2-MMP is expressed. |
| Databáze: |
Supplemental Index |
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