Delineation of proteolytic and non-proteolytic functions of the membrane-anchored serine protease prostasin

Abstract

The membrane-anchored serine proteases prostasin (PRSS8) and matriptase (ST14) initiate a cell surface proteolytic pathway essential for epithelial function. Mice expressing only catalytically inactive prostasin are viable, unlike prostasin null mice, indicating that at least some prostasin functions are non-proteolytic. Here we used knock-in mice expressing catalytically inactive prostasin (Prss8) to show that the physiological and pathological functions of prostasin vary in their dependence on its catalytic activity. Whereas prostasin null mice exhibited partial embryonic and complete perinatal lethality, Prss8Ki/Ki mice displayed normal prenatal and postnatal survival. Unexpectedly, catalytically inactive prostasin caused embryonic lethality in mice lacking its cognate inhibitors HAI-1 (SPINT1) or HAI-2 (SPINT2). Proteolytically inactive prostasin, unlike the wild-type protease, was unable to activate matriptase during placentation. Surprisingly, all essential functions of prostasin in embryonic and postnatal development were compensated for by loss of HAI-1, indicating that prostasin is only required for mouse development and overall viability in the presence of this inhibitor. This study expands our knowledge of non-proteolytic functions of membrane-anchored serine proteases and provides unexpected new data on the mechanistic interactions between matriptase and prostasin in the context of epithelial development.

Congenital sodium diarrhea and chorioretinal coloboma with optic disc coloboma in a patient with biallelic SPINT2 mutations, including p.(Tyr163Cys)

“…Spint2 is expressed in epithelial cells and is thought to regulate protease, serine 8 (PRSS8, or prostasin) that, together with matripase, is essential for terminal epidermal differentiation and tight junction formation (Szabo et al, 2016). It is possible to speculate that aberrant prostasin function could result in severe defects of epidermal barrier function that could compromise the function of corneal epithelial cells and cause surface erosions.…”

Transcriptome profiling and protease inhibition experiments identify proteases that activate H3N2 influenza A and influenza B viruses in murine airways

“…Prostasin activates the epithelial sodium channel (ENaC) by cleavage of the gamma subunit and plays important roles in epithelial development and tissue homeostasis (36,(42)(43)(44). Paradoxically, prostasin has been shown to require neither zymogen activation nor enzymatic activity to execute its important functions in epidermal development including activation of the ENaC (45)(46)(47). Other functions of prostasin, however, such as matriptase zymogen activation in the placenta were found to require its enzymatic activity (47).…”

“…Paradoxically, prostasin has been shown to require neither zymogen activation nor enzymatic activity to execute its important functions in epidermal development including activation of the ENaC (45)(46)(47). Other functions of prostasin, however, such as matriptase zymogen activation in the placenta were found to require its enzymatic activity (47). TMPRSS13 (also known as mosaic serine protease large-form (MSPL)) is present in various human tissues (48).…”

Selective Inhibition of Prostasin in Human Enterocytes by the Integral Membrane Kunitz-Type Serine Protease Inhibitor HAI-2

“…The limited resolution of SDS-PAGE and the presence of at least two prostasin species, which are likely the result of posttranslational modifications, make it very difficult to distinguish active prostasin from zymogen prostasin by immunoblot analysis [43]. Nevertheless, the specification of zymogen versus active prostasin by size difference has been also used in several previous studies [46][47][48]. In the study by Szabo et al, [46], the samples for immunoblot analysis were treated with reducing agent in order to dissociate active prostasin into the heavy chain and light chain.…”

“…Nevertheless, the specification of zymogen versus active prostasin by size difference has been also used in several previous studies [46][47][48]. In the study by Szabo et al, [46], the samples for immunoblot analysis were treated with reducing agent in order to dissociate active prostasin into the heavy chain and light chain. The samples were, however, not heat-treated as the immunoblot analysis was intended to detect prostasin-HAI-2 complexes.…”