Sodium retention in nephrotic syndrome is independent of the activation of the membrane-anchored serine protease prostasin (CAP1/PRSS8) and its enzymatic activity.

Experimental nephrotic syndrome leads to activation of the epithelial sodium channel (ENaC) by proteolysis and promotes renal sodium retention. The membrane-anchored serine protease prostasin (CAP1/PRSS8) is expressed in the distal nephron and participates in proteolytic ENaC regulation by serving as a scaffold for other serine proteases. However, it is unknown whether prostasin is also involved in ENaC-mediated sodium retention of experimental nephrotic syndrome.

Proteolytic activation of the epithelial sodium channel (ENaC) by factor VII activating protease (FSAP) and its relevance for sodium retention in nephrotic mice.

Proteolytic activation of the epithelial sodium channel (ENaC) by aberrantly filtered serine proteases is thought to contribute to renal sodium retention in nephrotic syndrome. However, the identity of the responsible proteases remains elusive. This study evaluated factor VII activating protease (FSAP) as a candidate in this context.

Essential role of DNA-PKcs and plasminogen for the development of doxorubicin-induced glomerular injury in mice.

Susceptibility to doxorubicin-induced nephropathy (DIN), a toxic model for the induction of proteinuria in mice, is related to the single-nucleotide polymorphism (SNP) C6418T of the Prkdc gene encoding for the DNA-repair enzyme DNA-PKcs. In addition, plasminogen (Plg) has been reported to play a role in glomerular damage. Here, we investigated the interdependence of both factors for the development of DIN.

Experimental nephrotic syndrome leads to proteolytic activation of the epithelial Na channel in the mouse kidney.

Proteolytic activation of the renal epithelial Na channel (ENaC) involves cleavage events in its α- and γ-subunits and is thought to mediate Na retention in nephrotic syndrome (NS). However, the detection of proteolytically processed ENaC in kidney tissue from nephrotic mice has been elusive so far. We used a refined Western blot technique to reliably discriminate full-length α-ENaC and γ-ENaC and their cleavage products after proteolysis at their proximal and distal cleavage sites (designated from the NH-terminus), respectively.

Renal effects of the serine protease inhibitor aprotinin in healthy conscious mice.

Treatment with aprotinin, a broad-spectrum serine protease inhibitor with a molecular weight of 6512 Da, was associated with acute kidney injury, which was one of the reasons for withdrawal from the market in 2007. Inhibition of renal serine proteases regulating the epithelial sodium channel ENaC could be a possible mechanism. Herein, we studied the effect of aprotinin in wild-type 129S1/SvImJ mice on sodium handling, tubular function, and integrity under a control and low-salt diet.

Plasminogen deficiency does not prevent sodium retention in a genetic mouse model of experimental nephrotic syndrome.

Aim: Sodium retention is the hallmark of nephrotic syndrome (NS) and mediated by the proteolytic activation of the epithelial sodium channel (ENaC) by aberrantly filtered serine proteases. Plasmin is highly abundant in nephrotic urine and has been proposed to be the principal serine protease responsible for ENaC activation in NS. However, a proof of the essential role of plasmin in experimental NS is lacking.

Urokinase-type plasminogen activator (uPA) is not essential for epithelial sodium channel (ENaC)-mediated sodium retention in experimental nephrotic syndrome.

Aim: In nephrotic syndrome, aberrantly filtered plasminogen (plg) is converted to active plasmin by tubular urokinase-type plasminogen activator (uPA) and thought to lead to sodium retention by proteolytic activation of the epithelial sodium channel (ENaC). This concept predicts that uPA is an important factor for sodium retention and that inhibition of uPA might be protective in nephrotic syndrome.

Methods: Activation of amiloride-sensitive currents by uPA and plg were studied in Xenopus laevis oocytes expressing murine ENaC.

Aprotinin prevents proteolytic epithelial sodium channel (ENaC) activation and volume retention in nephrotic syndrome.

Volume retention in nephrotic syndrome has been linked to activation of the epithelial sodium channel (ENaC) by proteolysis of its γ-subunit following urinary excretion of serine proteases such as plasmin. Here we tested whether pharmacological inhibition of urinary serine protease activity might protect from ENaC activation and volume retention in nephrotic syndrome. Urine from both nephrotic mice (induced by doxorubicin injection) and nephrotic patients exhibited high aprotinin-sensitive serine protease activity.

DOCA and TGF-beta induce early growth response gene-1 (Egr-1) expression.

Renal fibrosis is characterized by excessive accumulation of extracellular matrix proteins. Recent findings show that transforming growth factor-beta (TGF-beta) induces a rapid but transient expression of early growth response gene-1 (Egr-1) by skin fibroblasts. The present study aims to define the role of Egr-1 in mineralocorticoid-induced renal fibrosis.

Acute effects of haemodialysis on pro-/anti- apoptotic genes in peripheral blood leukocytes.

Several studies have implicated a remarkable dysfunctional apoptotic state and/or response in ESRD patients. Previously published studies are controversial with respect to acute effects of haemodialysis (HD) treatment on up- or downregulation of apoptotic genes. Twenty-eight chronic HD patients were haemodialysed for 4 hours with a 4008 dialyser using high-flux membranes.