Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033687 (proteinuria)
 24,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutations of NPHS1 or NPHS2, the genes encoding for the glomerular podocyte proteins nephrin and podocin, cause steroid-resistant proteinuria. In addition, mice lacking CD2-associated protein (CD2AP) develop a nephrotic syndrome that resembles NPHS mutations suggesting that all three proteins are essential for the integrity of glomerular podocytes. Although the precise glomerular function of either protein remains unknown, it has been suggested that nephrin forms zipper-like interactions to maintain the structure of podocyte foot processes. We demonstrate now that nephrin is a signaling molecule, which stimulates mitogen-activated protein kinases. Nephrin-induced signaling is greatly enhanced by podocin, which binds to the cytoplasmic tail of nephrin. Mutational analysis suggests that abnormal or inefficient signaling through the nephrin-podocin complex contributes to the development of podocyte dysfunction and proteinuria.
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PMID:Interaction with podocin facilitates nephrin signaling. 1156 57

In rat membranous nephropathy, complement C5b-9 induces glomerular epithelial cell (GEC) injury and proteinuria, which is partially mediated by eicosanoids. Rat GEC in culture express cyclooxygenase (COX)-1 constitutively, whereas COX-2 expression is induced by C5b-9. Both isoforms contribute to complement-induced prostaglandin generation. The present study addresses mechanisms of complement-induced COX-2 expression in GEC. Downregulation of protein kinase C (PKC) blunted complement-induced upregulation of COX-2 mRNA. Complement and phorbol 12-myristate 13-acetate (PMA) both stimulated COX-2 promoter activity. C5b-9 activated c-Jun NH(2)-terminal kinase (JNK), and inhibition of JNK activity by transfection of a kinase-inactive JNK1 partially inhibited complement-induced (but not PMA-induced) COX-2 promoter activation. Conversely, a constitutively active mitogen-activated protein or extracellular signal-regulated kinase kinase kinase (MEKK)-1, a kinase upstream of JNK, increased COX-2 promoter activity. MEKK-induced COX-2 promoter activation was not affected by downregulation of PKC and was augmented by PMA. Thus, in GEC, PKC and JNK pathways contribute independently to complement-induced COX-2 expression. Nuclear factor-kappaB was also activated by complement in GEC but did not contribute to complement-induced COX-2 upregulation.
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PMID:Complement C5b-9 induces cyclooxygenase-2 gene transcription in glomerular epithelial cells. 1159 42

Although debated for many years whether haemodynamic or structural changes are more important in the development of diabetic nephropathy, it is now clear that these processes are interwoven and present two sides of one coin. On a molecular level, hyperglycaemia and proteins altered by high blood glucose such as Amadori products and advanced glycation end-products (AGEs) are key players in the development of diabetic nephropathy. Recent evidence suggests that an increase in reactive oxygen species (ROS) formation induced by high glucose-mediated activation of the mitochondrial electron-transport chain is an early event in the development of diabetic complications. A variety of growth factors and cytokines are then induced through complex signal transduction pathways involving protein kinase C, mitogen-activated protein kinases, and the transcription factor NF-kappaB. High glucose, AGEs, and ROS act in concert to induce growth factors and cytokines. Particularly, TGF-beta is important in the development of renal hypertrophy and accumulation of extracellular matrix components. Activation of the renin-angiotensin system by high glucose, mechanical stress, and proteinuria with an increase in local formation of angiotensin II (ANG II) causes many of the pathophysiological changes associated with diabetic nephropathy. In fact, it has been shown that angiotensin II is involved in almost every pathophysiological process implicated in the development of diabetic nephropathy (haemodynamic changes, hypertrophy, extracellular matrix accumulation, growth factor/cytokine induction, ROS formation, podocyte damage, proteinuria, interstitial inflammation). Consequently, blocking these deleterious effects of ANG II is an essential part of every therapeutic regiment to prevent and treat diabetic nephropathy. Recent evidence suggests that regression of diabetic nephropathy could be achieved under certain circumstances.
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PMID:New insights into the pathophysiology of diabetic nephropathy: from haemodynamics to molecular pathology. 1560 19

Extracellular signals may be transmitted to nuclear or cytoplasmic effectors via the mitogen-activated protein kinases. In the passive Heymann nephritis (PHN) model of membranous nephropathy, complement C5b-9 induces glomerular epithelial cell (GEC) injury, proteinuria, and activation of phospholipases and protein kinases. This study addresses the complement-mediated activation of the extracellular signal-regulated kinase (ERK). C5b-9 induced ERK threonine202/tyrosine204 phosphorylation (which correlates with activation) in GEC in culture and PHN in vivo. Expression of a dominant-inhibitory mutant of Ras reduced complement-mediated activation of ERK, but activation was not affected significantly by downregulation of protein kinase C. Complement-induced ERK activation resulted in phosphorylation of cytosolic phospholipase A2 and was, in part, responsible for phosphorylation of mitogen-activated protein kinase-associated protein kinase-2, but did not induce phosphorylation of the transcription factor, Elk-1. Activation of ERK was attenuated by drugs that disassemble the actin cytoskeleton (cytochalasin D, latrunculin B), and these compounds interfered with the activation of ERK by mitogen-activated protein kinase kinase (MEK). Overexpression of a constitutively active RhoA as well as inhibition of Rho-associated kinase blocked complement-mediated ERK activation. Complement cytotoxicity was enhanced after disassembly of the actin cytoskeleton but was unaffected after inhibition of complement-induced ERK activation. However, complement cytotoxicity was enhanced in GEC that stably express constitutively active MEK. Thus complement-induced ERK activation depends on cytoskeletal remodelling and affects the regulation of distinct downstream substrates, while chronic, constitutive ERK activation exacerbates complement-mediated GEC injury.
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PMID:Activation of the extracellular signal-regulated kinase by complement C5b-9. 1585 57

Podocytes play an important role in maintaining normal glomerular function and structure, and podocyte injury leads to proteinuria and glomerulosclerosis. The family of mitogen-activated protein kinases (MAPK; extracellular signal-regulated kinase [ERK], c-Jun N-terminal kinase, and p38) may be implicated in the progression of various glomerulopathies, but the role of MAPK in podocyte injury remains elusive. This study examined phosphorylation of p38 MAPK in clinical glomerulopathies with podocyte injury, as well as in rat puromycin aminonucleoside (PAN) nephropathy and mouse adriamycin (ADR) nephropathy. The effect of treatment with FR167653, an inhibitor of p38 MAPK, was also investigated in rodent models. In human podocyte injury diseases, the increased phosphorylation of p38 MAPK was observed at podocytes. In PAN and ADR nephropathy, the phosphorylation of p38 MAPK and ERK was marked but transient, preceding overt proteinuria. Pretreatment with FR167653 (day -2 to day 14, subcutaneously) to PAN or ADR nephropathy completely inhibited p38 MAPK activation and attenuated ERK phosphorylation, with complete suppression of proteinuria. Electron microscopy and immunohistochemistry for nephrin and connexin43 revealed that podocyte injury was markedly ameliorated by FR167653. Furthermore, early treatment with FR167653 effectively prevented glomerulosclerosis and renal dysfunction in the chronic phase of ADR nephropathy. In cultured podocytes, PAN or oxidative stress induced the phosphorylation of p38 MAPK along with actin reorganization, and FR167653 inhibited such changes. These findings indicate that the activation of MAPK is necessary for podocyte injury, suggesting that p38 MAPK and, possibly, ERK should become a potential target for therapeutic intervention in proteinuric glomerulopathies.
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PMID:Role of p38 mitogen-activated protein kinase activation in podocyte injury and proteinuria in experimental nephrotic syndrome. 1598 52

Recent clinical and pre-clinical studies have indicated the utility of mineralocorticoid receptor (MR) antagonists in renal injury. We have demonstrated in rats that chronic treatment with aldosterone results in severe proteinuria and renal injury, characterized by glomerular changes, tubulointerstitial fibrosis, and collagen accumulation. We also observed increased reactive oxygen species (ROS) generation and mitogen-activated protein kinases (MAPKs) activity in renal cortical tissues. Treatment with a selective MR antagonist, eplerenone, prevented elevation of ROS levels and MAPK activity, as well as ameliorating renal injury. In vitro studies revealed that MRs are highly expressed in rat glomerular mesangial cells (RMC) and rat renal fibroblasts. In RMC, aldosterone induces cellular injuries through NADPH oxidase-dependent ROS production and/or MAPK activation. Aldosterone-induced renal cellular injuries were markedly attenuated by treatment with eplerenone. These data suggest that aldosterone induces renal injury through activation of MRs and support the notion that MR blockade has beneficial effects on aldosterone-dependent renal injury through mechanisms that cannot be simply explained by hemodynamic changes. In this review, we summarized our recent findings pertaining to the roles of aldosterone and MRs in the pathogenesis of renal injury. Potential molecular mechanisms responsible for aldosterone/MR-induced renal injury were also discussed.
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PMID:Molecular mechanisms and therapeutic strategies of chronic renal injury: renoprotective effects of aldosterone blockade. 1639 74

The existence of a tissue renin-angiotensin (RAS) system independent of the circulating RAS has prompted the search for cellular binding sites for angiotensinogen and for renin in order to explain their tissue uptake. Two receptors that bind with similar affinity mature renin and prorenin were identified, the mannose-6-phosphate receptor (M6P-R) and a specific receptor. The M6P-R is a clearance receptor that binds exclusively the glycosylated forms of renin and prorenin. Binding of renin and prorenin to the M6P-R is followed by internalization and degradation, and the intracellular proteolysis of prorenin in mature renin did not provoke any generation of intracellular angiotensins. In contrast to the M6P-R, (pro)renin bound to the specific receptor was not degraded. Instead, receptor-bound renin showed increased catalytic activity, and receptor-bound prorenin exhibited full catalytic activity. This 'gain of activity' was explained by a conformational change of the (pro)renin molecule upon binding. Furthermore, (pro)renin binding provoked a rapid activation of the mitogen-activated protein kinases p44/p42, indicating that the receptor has mediated specific, angiotensin II-independent effects of (pro)renin. This receptor represents an elegant concept to explain the existence of active prorenin in vivo, and it provides a pathological role for prorenin in situations with paradoxical low renin and high prorenin concentrations such as in diabetes. Experimental models of rats overexpressing the receptor either in vascular smooth muscle cells and developing high blood pressure or with ubiquitous expression associated with glomerulosclerosis and proteinuria confirm a role for the receptor in cardiovascular and renal diseases.
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PMID:Renin/prorenin receptors. 1667 20

Tissue factor initiates the extrinsic coagulation pathway by activating coagulation factor X to factor Xa, and factor V is a cofactor for the prothrombin activation by factor Xa. As factor Xa is known to promote the proliferation of mesangial cells in culture, the roles of the coagulation pathway and factor Xa were studied in an animal model of mesangioproliferative glomerulonephritis (MsPGN). MsPGN was induced in Wistar rats by an intravenous injection of anti-Thy 1.1 monoclonal antibody, OX-7. To clarify the role of factor Xa in MsPGN, a specific factor Xa inhibitor, DX-9065a, was injected intravenously at 2.5 or 10 mg/kg at the same time as OX-7, and kidney involvement was assessed by immunohistological analyses. We also examined p44/42 mitogen-activated protein (MAP) kinase activation. Time-course study revealed that expressions of tissue factor, factor V, and protease-activated receptor 2 (PAR2) were peaked on day 3, followed by factor X accumulation and mesangial proliferation. DX-9065a treatment significantly ameliorated proteinuria in a dose-dependent manner on day 8. Histological analyses showed a significant reduction in the size of glomeruli, the total number of glomerular cells, and crescent formation by DX-9065a treatment. Macrophage infiltration, which was rapidly observed on day 1 in disease control rats was not inhibited on days 1-3 by DX-9065a treatment, however it was suppressed on days 5-8. The deposition of fibrin, the number of PCNA-positive cells, and phosphorylation of p44/42 MAP kinase were markedly increased in the disease control group, whereas they were significantly reduced in the treatment group. Tissue factor and factor V induction may accelerate MsPGN through the activation and accumulation of factor X via proinflammatory and procoagulant mechanisms, and the inhibition of factor Xa would be a promising method to regulate the disease process.
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PMID:Roles of coagulation pathway and factor Xa in rat mesangioproliferative glomerulonephritis. 1717 58

The progression of renal disease displays several characteristics, including proteinuria, apoptosis, inflammation, and fibrosis. In this study, we investigated the effect of long-term infusion of kinin in protection against salt-induced renal damage in Dahl salt-sensitive rats. Dahl salt-sensitive rats were fed a high-salt diet for 2 weeks and were then infused with bradykinin (500 ng/h) via subcutaneously implanted minipumps for 3 weeks. Kinin infusion attenuated salt-induced impaired renal function as evidenced by reduced proteinuria, serum creatinine, and blood urea nitrogen levels without apparent effect on blood pressure. Morphological analysis indicated that kinin administration reduced salt-induced glomerular sclerosis, tubular dilatation, luminal protein cast formation, and interlobular arterial thickness. Kinin also significantly lowered collagen I, III, and IV deposition and their mRNA levels. Moreover, kinin reduced interstitial monocyte/macrophage accumulation, as well as tubular cell apoptosis and caspase-3 activity. Protection of renal injury by kinin was associated with increased renal NO levels and reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate oxidase activities and superoxide generation. Suppression of oxidative stress by kinin was accompanied by reduced transforming growth factor-beta1 protein and mRNA levels, as well as decreased phosphorylation of mitogen-activated protein kinases. This is the first study to demonstrate that kinin infusion can directly protect against salt-induced renal injury without blood pressure reduction by inhibiting apoptosis, inflammation, and fibrosis via suppression of oxidative stress, transforming growth factor-beta1 expression, and mitogen-activated protein kinase activation.
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PMID:Kinin infusion prevents renal inflammation, apoptosis, and fibrosis via inhibition of oxidative stress and mitogen-activated protein kinase activity. 1722 75

Gestational diabetes (GD, characterized by abnormal D-glucose metabolism), intrauterine growth restriction (IUGR, a disease associated with reduced oxygen delivery (hypoxia) to the foetus), and preeclampsia (PE, a pregnancy complication characterized by high blood pressure, proteinuria and increased vascular resistance), induce foetal endothelial dysfunction with implications in adult life and increase the risk of vascular diseases. Synthesis of nitric oxide (NO) and uptake of L-arginine (the NO synthase (NOS) substrate) and adenosine (a vasoactive endogenous nucleoside) by the umbilical vein endothelium is altered in pregnancies with GD, IUGR or PE. Mechanisms underlying these alterations include differential expression of equilibrative nucleoside transporters (ENTs), cationic amino acid transporters (CATs), and NOS. Modulation of ENTs, CATs, and NOS expression and activity in endothelium involves protein kinase C (PKC), mitogen-activated protein kinases p42 and p44 (p42/44(mapk)), calcium, and phosphatidyl inositol 3 kinase (PI3k), among others. Elevated extracellular D-glucose and hypoxia alter human endothelial function. However, information regarding the transcriptional modulation of ENTs, CATs, and NOS is limited. This review focuses on the effect of transcriptional and post-transcriptional regulatory mechanisms involved in the modulation of ENTs and CATs, and NOS expression and activity, and the consequences for foetal endothelial function in GD, IUGR and PE. The available information will contribute to a better understanding of the cell and molecular basis of the altered vascular endothelial function in these pregnancy diseases and will emphasize the key role of this type of epithelium in placental function and the normal foetal development and growth.
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PMID:Equilibrative nucleoside (ENTs) and cationic amino acid (CATs) transporters: implications in foetal endothelial dysfunction in human pregnancy diseases. 1726 15


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