Loss of either hepatocyte growth factor activator inhibitor (HAI)-1 or -2 is associated with embryonic lethality in mice, which can be rescued by the simultaneous inactivation of the membrane-anchored serine protease, matriptase, thereby demonstrating that a matriptase-dependent proteolytic pathway is a critical developmental target for both protease inhibitors. Here, we performed a genetic epistasis analysis to identify additional components of this pathway by generating mice with combined deficiency in either HAI-1 or HAI-2, along with genes encoding developmentally co-expressed candidate matriptase targets, and screening for the rescue of embryonic development. Hypomorphic mutations in Prss8, encoding the GPI-anchored serine protease, prostasin (CAP1, PRSS8), restored placentation and normal development of HAI-1–deficient embryos and prevented early embryonic lethality, mid-gestation lethality due to placental labyrinth failure, and neural tube defects in HAI-2–deficient embryos. Inactivation of genes encoding c-Met, protease-activated receptor-2 (PAR-2), or the epithelial sodium channel (ENaC) alpha subunit all failed to rescue embryonic lethality, suggesting that deregulated matriptase-prostasin activity causes developmental failure independent of aberrant c-Met and PAR-2 signaling or impaired epithelial sodium transport. Furthermore, phenotypic analysis of PAR-1 and matriptase double-deficient embryos suggests that the protease may not be critical for focal proteolytic activation of PAR-2 during neural tube closure. Paradoxically, although matriptase auto-activates and is a well-established upstream epidermal activator of prostasin, biochemical analysis of matriptase- and prostasin-deficient placental tissues revealed a requirement of prostasin for conversion of the matriptase zymogen to active matriptase, whereas prostasin zymogen activation was matriptase-independent.

Background: Matriptase and prostasin form a proteolytic pathway in which the hierarchical placement of the two proteases is unclear. Results: Prostasin stimulates matriptase activation non-enzymatically. Matriptase zymogen can activate prostasin. Conclusion: Matriptase and prostasin form a reciprocal zymogen activation complex with unique features. Significance: A general model for activation of the two membrane-anchored serine proteases is proposed.

The membrane-anchored serine protease, matriptase, is consistently dysregulated in a range of human carcinomas, and high matriptase activity correlates with poor prognosis. Furthermore, matriptase is unique among tumor-associated proteases in that epithelial stem cell expression of the protease suffices to induce malignant transformation. Here, we use genetic epistasis analysis to identify proteinase-activated receptor (PAR)-2-dependent inflammatory signaling as an essential component of matriptase-mediated oncogenesis. In cell-based assays, matriptase was a potent activator of PAR-2, and PAR-2 activation by matriptase caused robust induction of NFκB through Gαi. Importantly, genetic elimination of PAR-2 from mice completely prevented matriptase-induced pre-malignant progression, including inflammatory cytokine production, inflammatory cell recruitment, epidermal hyperplasia, and dermal fibrosis. Selective ablation of PAR-2 from bone marrow-derived cells did not prevent matriptase-driven pre-malignant progression, indicating that matriptase activates keratinocyte stem cell PAR-2 to elicit its pro-inflammatory and pro-tumorigenic effects. When combined with previous studies, our data suggest that dual induction of PAR-2-NFκB inflammatory signaling and PI3K-Akt-mTor survival/proliferative signaling underlies the transforming potential of matriptase and may contribute to pro-tumorigenic signaling in human epithelial carcinogenesis.

Numerous alterations in the distribution of enteroendocrine cells and their expression of hormonal genes are seen after RYGB and include increased density of GLP-1-, PYY-, CCK-, GIP- and PC2-positive cells, reduced gene expression of GHRL, SCT and GIP and increased expression of GCG.

Background: Hepatocyte growth factor activator inhibitor (HAI)-1 and HAI-2 may regulate matriptase trafficking and activation. Results: Ablation of endogenous HAI-2, but not HAI-1, causes loss of epithelial matriptase in vivo and in vitro, due to uncontrolled prostasin-dependent activation and shedding. Conclusion: HAI-2, but not HAI-1, regulates matriptase cell surface expression level. Significance: The study identifies HAI-2 as a principal regulator of prostasin-mediated matriptase activation.

Objective To examine the impact of peritoneal dialysis catheter configuration, curled or straight catheter, on catheter survival and mechanical and infectious complications. Design Prospective randomized trial. Setting Department of Nephrology of a single university hospital. Patients Seventy-two consecutive patients initiating peritoneal dialysis were randomized to receive either a single cuff straight catheter or a single cuff curled catheter, implanted by percutaneous technique. Results Significantly higher (p < 0.01) survival rate of the curled as compared to the straight catheter. The difference in catheter survival was due to a significantly higher (p < 0.01) incidence of drainage failure associated with catheter tip migration of the straight catheter than of the curled catheter. No difference in infectious complication between the two types of catheters was seen. Catheter survival at 12 months was 77% for the curled catheter and 36% for the straight catheter. Conclusion This study demonstrates superiority of the curled Tenckhoff peritoneal dialysis catheter survival as compared to the straight catheter. This difference in catheter survival is due to the higher displacement rate of the straight catheter.

The membrane-anchored serine prostasin (CAP1/PRSS8) is essential for barrier acquisition of the interfollicular epidermis and for normal hair follicle development. Consequently, prostasin null mice die shortly after birth. Prostasin is found in two forms in the epidermis: a one-chain zymogen and a two-chain proteolytically active form, generated by matriptase-dependent activation site cleavage. Here we used gene editing to generate mice expressing only activation site cleavage-resistant (zymogen-locked) endogenous prostasin. Interestingly, these mutant mice displayed normal interfollicular epidermal development and postnatal survival, but had defects in whisker and pelage hair formation. These findings identify two distinct in vivo functions of epidermal prostasin: a function in the interfollicular epidermis, not requiring activation site cleavage, that can be mediated by the zymogen-locked version of prostasin and a proteolysis-dependent function of activated prostasin in hair follicles, dependent on zymogen conversion by matriptase.Prostasin (also known as channel-activating protease-1, CAP1, and PRSS8) is a glycosylphosphatidylinositol-anchored trypsin-like serine protease that is widely expressed in epithelial tissues, including both the interfollicular and the follicular compartments of the epidermis. Loss-of-function genetic studies in mice have uncovered critical functions of prostasin in both the formation of epidermal barrier formation and the formation of whiskers and pelage hair (1, 2). Prostasin is synthesized as an inactive proform (zymogen) that is converted to a catalytically active protease by a single endoproteolytic cleavage in the conserved activation cleavage site (3-6). Prostasin zymogen conversion in the epidermis requires the membraneactivated serine protease matriptase (7-9). This observation, combined with the observation that both matriptase-deficient and prostasin-deficient mice display identical epidermal phenotypes, led to the formulation of the hypothesis that prostasin exerts its functions in this tissue as part of a matriptase-prostasin cell surface zymogen activation cascade (8). Several observations made during the last decade suggest, however, that prostasin may also execute biological functions independent of its own proteolytic activity. For example, in a reconstituted Xenopus oocyte system, prostasin can activate the epithelial sodium channel (ENaC) by inducing proteolytic cleavage of its ␥ subunit to release an inhibitory domain. However, this activation, which can be inhibited by the broad-spectrum serine protease inhibitor, aprotinin, can also be efficiently executed by mutant prostasin variants that lack the catalytic histidine-aspartate-serine triad (10 -12). Likewise, catalytically inactive prostasin mutants can stimulate the activation of protease-activated receptor-2 in a reconstituted mammalian cell-based system (13). Strong support for a non-proteolytic function of prostasin in vivo has been gained from the observation that mis-expressed catalytically inactive pros...

The matriptase-prostasin proteolytic cascade is essential for epidermal tight junction formation and terminal epidermal differentiation. This proteolytic pathway may also be operative in a variety of other epithelia, as both matriptase and prostasin are involved in tight junction formation in epithelial monolayers. However, in polarized epithelial cells matriptase is mainly located on the basolateral plasma membrane whereas prostasin is mainly located on the apical plasma membrane. To determine how matriptase and prostasin interact, we mapped the subcellular itinerary of matriptase and prostasin in polarized colonic epithelial cells. We show that zymogen matriptase is activated on the basolateral plasma membrane where it is able to cleave relevant substrates. After activation, matriptase forms a complex with the cognate matriptase inhibitor, hepatocyte growth factor activator inhibitor (HAI)-1 and is efficiently endocytosed. The majority of prostasin is located on the apical plasma membrane albeit a minor fraction of prostasin is present on the basolateral plasma membrane. Basolateral prostasin is endocytosed and transcytosed to the apical plasma membrane where a long retention time causes an accumulation of prostasin. Furthermore, we show that prostasin on the basolateral membrane is activated before it is transcytosed. This study shows that matriptase and prostasin co-localize for a brief period of time at the basolateral plasma membrane after which prostasin is transported to the apical membrane as an active protease. This study suggests a possible explanation for how matriptase or other basolateral serine proteases activate prostasin on its way to its apical destination.The trypsin-like membrane serine protease matriptase is essential for maintenance of multiple types of epithelia. Conditional ablation of the St14 gene coding for matriptase in intestine, kidney, and lung of adult mice results in weight loss, severe decline in health and death within 2 weeks, caused by organ dysfunction associated with increased permeability and loss of tight junctions (1). Knock down of matriptase by siRNA in a cell model of the intestinal epithelium caused a leaky barrier, impaired ability to develop transepithelial electrical resistance (TEER) 2 and enhanced paracellular permeability through regulation of tight junction proteins (2). Together these data suggest a key role for matriptase in epithelial barrier function and tight junction assembly.Prostasin (also known as CAP1 and PRSS8) is a GPI-anchored trypsin-like serine protease. Prostasin is co-expressed with matriptase in most epithelial tissues including the epidermis, kidney, and colon (3). Prostasin proteolytic activity has also been suggested to promote the development of functional tight junctions, TEER and paracellular permeability (4 -6). Unlike matriptase, which undergoes efficient autoactivation, the prostasin zymogen is not able to auto-activate, and formation of active prostasin requires activation site cleavage by other trypsin-like serine proteases. Strong...