The Activation of Matriptase Requires Its Noncatalytic Domains, Serine Protease Domain, and Its Cognate Inhibitor

Abstract

The activation of matriptase requires proteolytic cleavage at a canonical activation motif that converts the enzyme from a one-chain zymogen to an active, twochain protease. In this study, matriptase bearing a mutation in its catalytic triad was unable to undergo this activational cleavage, suggesting that the activating cleavage occurs via a transactivation mechanism where interaction between matriptase zymogen molecules leads to activation of the protease. Using additional point and deletion mutants, we showed that activation of matriptase requires proteolytic processing at Gly-149 in the SEA domain of the protease, glycosylation of the first CUB domain and the serine protease domain, and intact low density lipoprotein receptor class A domains. Its cognate inhibitor, hepatocyte growth factor activator inhibitor-1, may also participate in the activation of matriptase, based on the observation that matriptase activation did not occur when the protease was co-expressed with hepatocyte growth factor activator inhibitor-1 mutated in its low density lipoprotein receptor class A domain. These results suggest that besides matriptase catalytic activity, matriptase activation requires post-translational modification of the protease, intact noncatalytic domains, and its cognate inhibitor.

Membrane-Bound Serine Protease Inhibitor HAI-1 Is Required for Maintenance of Intestinal Epithelial Integrity

“…6 -9 Recent studies suggested that HAI-1/ SPINT1 is responsible not only for the inhibition of matriptase activity but also for the proper intracellular trafficking and activation of matriptase in polarized human epithelial cells. [22][23][24][25][26] We hypothesize that the maintenance of adequate matriptase activity at its proper subcellular localization might require HAI-1/SPINT1. The altered immunolocalization pattern of matriptase observed in the disorganized crypt epithelial cells of the HAI-1/SPINT1-deficient colon may support this hypothesis.…”

Matriptase inhibition by hepatocyte growth factor activator inhibitor-1 is essential for placental development

“…It is therefore formally possible that HAI-1 does not act directly on matriptase during development, but rather on other proteases that act either upstream or downstream of matriptase in a matriptase-dependent proteolytic pathway. However, for the following reasons this does not seem likely: First, biochemical studies have shown that HAI-1 binds directly to matriptase with high affinity and efficiently inhibits matriptase proteolytic activity (Oberst et al, 2003b(Oberst et al, , 2005. Second, shed endogenous matriptase has been isolated in a complex with shed endogenous HAI-1 in breast milk, indicating that a direct interaction occurs between matriptase and HAI-1 when co-expressed in vivo (Lin et al, 1999).…”

Requirement of the activity of hepatocyte growth factor activator inhibitor type 1 for the extracellular appearance of a transmembrane serine protease matriptase in monkey kidney COS-1 cells

“…The molecular-mass standards are indicated on the left of each blot in kDa. The position at which the catalytic domain part of activated matriptase migrates is indicated on the left by an arrowhead lipoprotein receptor class A (LDLRA) domain (designated D349Y HAI-1), the activated matriptase occurred rarely (Oberst et al 2003b). Therefore, the LDLRA domain of HAI-1 was postulated to play an important role in the process of matriptase activation (Oberst et al 2003b).…”

“…The position at which the catalytic domain part of activated matriptase migrates is indicated on the left by an arrowhead lipoprotein receptor class A (LDLRA) domain (designated D349Y HAI-1), the activated matriptase occurred rarely (Oberst et al 2003b). Therefore, the LDLRA domain of HAI-1 was postulated to play an important role in the process of matriptase activation (Oberst et al 2003b). In the present study, we found that the level of activated WT-matriptase that occurred in the conditioned medium from HAI58K-co-expressing cells was similar to that from HAI-KD1-co-expressing cells (Fig.…”

“…The activation of this protease (i.e., conversion to disulfide-linked two-chain form via cleavage after Arg614, Fig. 2a) is known to occur via a mechanism requiring its catalytic triad (Takeuchi et al 1999;Oberst et al 2003b;Désilets et al 2008;Miyake et al 2009). The activated two-chain protease cleaves to activate a number of substrates, including pro-HGF, possibly at the cell surface (Lee et al 2000;Satomi et al 2001;Yamasaki et al 2003;Kojima et al 2009a).…”