Urokinase-type Plasminogen Activator (uPA) Induces Pulmonary Microvascular Endothelial Permeability through Low Density Lipoprotein Receptor-related Protein (LRP)-dependent Activation of Endothelial Nitric-oxide Synthase

Abstract

Urokinase plasminogen activator (uPA) and PA inhibitor type 1 (PAI-1) are elevated in acute lung injury, which is characterized by a loss of endothelial barrier function and the development of pulmonary edema. Two-chain uPA and uPA-PAI-1 complexes (1-20 nM) increased the permeability of monolayers of human pulmonary microvascular endothelial cells (PMVECs) in vitro and lung permeability in vivo. The effects of uPA-PAI-1 were abrogated by the nitric-oxide synthase (NOS) inhibitor L-NAME (N D -nitro-L-arginine methyl ester). Two-chain uPA (1-20 nM) and uPA-PAI-1 induced phosphorylation of endothelial NOS-Ser 1177 in PMVECs, which was followed by generation of NO and the nitrosylation and dissociation of ␤-catenin from VE-cadherin. uPA-induced phosphorylation of eNOS was decreased by anti-low density lipoprotein receptor-related protein-1 (LRP) antibody and an LRP antagonist, receptor-associated protein (RAP), and when binding to the uPA receptor was blocked by the isolated growth factor-like domain of uPA. uPAinduced phosphorylation of eNOS was also inhibited by the protein kinase A (PKA) inhibitor, myristoylated PKI, but was not dependent on PI3K-Akt signaling. LRP blockade and inhibition of PKA prevented uPA-and uPA-PAI-1-induced permeability of PMVEC monolayers in vitro and uPA-induced lung permeability in vivo. These studies identify a novel pathway involved in regulating PMVEC permeability and suggest the utility of uPAbased approaches that attenuate untoward permeability following acute lung injury while preserving its salutary effects on fibrinolysis and airway remodeling.

Heterogeneity in relaxation of different sized porcine coronary arteries to nitrovasodilators: role of PKG and MYPT1

“…cGMP may cause vasodilatation by cross-acting on cAMP-dependent protein kinase [9]. In the present study, myristoylated PKI, a cell membrane-permeable specific inhibitor of PKA [5,13,18,33], had no significant effect on relaxations of coronary arteries induced by nitroglycerin, DETA NONOate, and 8-Br-cGMP. Our previous studies show that in porcine coronary arteries and veins, myristoylated PKI at the concentration used had no effect on PKG activity stimulated by cGMP but fully blocked the activity of PKA stimulated by cAMP, which was associated with a significant reduction of vasodilator response to 8-Br-cAMP [38,39].…”

“…Relaxation of different sized arteries induced by nitroglycerin, DETA NONOate, and 8-Br-cGMP was not affected by myristoylated PKI (6×10 −6 M), a specific inhibitor of PKA [5,13,18,33] (Fig. 4).…”

Effects of early enteral nutrition on the gastrointestinal motility and intestinal mucosal barrier of patients with burn-induced invasive fungal infection

“…Enteral nutrition helps maintain the structural and functional integrities of the intestinal mucosa, and the irritation of food on intestinal mucous membrane is conducive to promoting the secretion of gastrointestinal hormones, gallbladder contractibility and gastrointestinal peristalsis as well as protecting the intestinal barrier function. 19 In this study, there were no significant differences between both groups during treatment in the incidence rates of complications such as abdominal distension, diarrhea, sepsis, nausea, vomiting and gastric retention. In addition, the mean healing time was 9.34±0.78 days in the EN group and 12.46±2.19 days in the PN group, of which the former was significantly shorter than the latter (P<0.05).…”

tPA variant tPA‐A296–299 Prevents impairment of cerebral autoregulation and necrosis of hippocampal neurons after stroke by inhibiting upregulation of ET‐1

“…Possibilities include alterations in cell surface receptor subunit expression, receptor cleavage by tPA, ion gating, and/ or changes signaling after stroke. Prior studies from our group demonstrating that uPA activates endothelial nitric oxide synthase in an LRP dependent manner (Makarova et al, 2011) provides precedent for our hypothesis. We hypothesize that elevation of cAMP will cause p38 release, which will inhibit JNK ( Figure 5, left pathway).…”