Regulation of Membrane Type-1 Matrix Metalloproteinase Activation by Proprotein Convertases

Abstract

Membrane type-1 matrix metalloproteinase (MT1-MMP) is the prototypical member of a subgroup of membrane-anchored proteinases that belong to the matrix metalloproteinase family. Although synthesized as a zymogen, MT1-MMP plays an essential role in extracellular matrix remodeling after an undefined process that unmasks its catalytic domain. We now report the existence of a proprotein convertase-MT1-MMP axis that regulates the processing and functional activity of the metalloproteinase. Two sets of basic motifs in the propeptide region of MT1-MMP are identified that potentially can be recognized by the proprotein convertase family of subtilisinlike proteases. Processing of proMT1-MMP as well as the expression of its proteolytic activity were blocked by mutating these recognition motifs or by inhibiting the proprotein convertases furin and PC6 with the serpin-based inhibitor ␣ 1 antitrypsin Portland. Furthermore, both furindependent and furin-independent MT1-MMP processing pathways are identified that require tethering of the metalloproteinase to the cell surface. These findings demonstrate the existence of a proprotein convertase-MT1-MMP axis that can regulate extracellular matrix remodeling.

Furin regulates the intracellular activation and the uptake rate of cell surface-associated MT1-MMP

“…Inactivation of the furin sites by the ARAA and the R89A mutations were convincingly established by earlier works (Yana and Weiss, 2000;Cao et al, 2005). Glioma cells expressing these constructs were lysed and the lysates were analysed by Western blotting with an MT1-MMP antibody.…”

“…Processing of the peptides that span the membrane type-1 matrix metalloproteinase furin cleavage motifs The furin cleavage of MT1-MMP at the R 89 -R-P-R-C 93 and R 108 -R-K-R-Y 112 motifs (Yana and Weiss, 2000) should, in theory, generate the proteinase species commencing at Cys 93 and Tyr 112 , respectively. According to the N-terminal sequencing of cellular MT1-MMP, the Tyr 112 -species represents the fully mature enzyme (Strongin et al, 1995).…”

“…To exercise its functional activity, MT1-MMP requires removal of the N-terminal prodomain sequence. There are two potential furin cleavage motifs, R 89 -R-P-R-kC 93 and R 108 -R-K-R-kY 112 in the prodomain of MT1-MMP (Pei and Weiss, 1995;Yana and Weiss, 2000). Similar motifs exist in the sequence of certain other MMPs.…”

“…Similar motifs exist in the sequence of certain other MMPs. In the course of the secretory pathway of MT1-MMP, these motifs are targeted by furin and also by other cellular PCs (Stawowy et al, 2005) because partial MT1-MMP maturation was observed in furin-deficient cells (Yana and Weiss, 2000). Seven furin-like PCs are known: furin/ PACE/PC1, PC2, PC1/3, PACE4, PC4, PC5/6, and PC7 (Fugere and Day, 2005).…”

“…There is evidence that a portion of the cellular MT1-MMP pool is processed by additional PCs and also by autocatalysis directly at the cell surface (Sato et al, 1999;Yana and Weiss, 2000;Rozanov and Strongin, 2003;Deryugina et al, 2004). Inhibition of MT1-MMP activation by furin inhibitors, including a nanomolar range a1-anti-trypsin variant Portland (PDX) inhibitor repressed motility and tumorigenicity of cancer cells (Bassi et al, 2001).…”