Melanoma Differentiation-Associated Gene 5 Regulates the Expression of a Chemokine CXCL10 in Human Mesangial Cells: Implications for Chronic Inflammatory Renal Diseases

Angiotensin II (ANG II) has been shown to activate c-Jun NH2-terminal kinase (JNK) in cultured mesangial cells, but the functional implication of this phenomenon remains to be determined, largely due to the lack of an effective approach to block JNK. Therefore, the present study was carried out to examine whether JNK is involved in ANG II-induced cell proliferation in cultured human mesangial cells (HMCs) with the use of a newly developed JNK-selective blocker, SP-600125. Within minutes, treatment with 100 nM ANG II activated all three members of MAP kinase family, including extracellular signal-regulated protein kinase (Erk) 1/2, JNK, and p38 in cultured HMCs, as assessed by immunoblotting detection of phosphorylation of MAP kinases. ANG II-dependent activation of JNK was further confirmed by detection of increased phosphorylation and transcription activity of c-Jun after the ANG II treatment. SP-600125 ranging from 5 to 10 μM almost completely abolished the activation of JNK by ANG II without affecting the activities of Erk1/2 and p38. After treatment with 100 ng ANG II, there was a steady increase in [3H]thymidine incorporation that was blocked by SP-60025 in a dose- and time-dependent manner. Similarly, SP-600125 dose dependently reduced the ANG II-induced increase in cell number. The antiproliferative effect of SP-60025 was further determined by cell-cycle analysis with flow cytometry. Twenty-four hours after ANG II treatment, 50% of the quiescent HMCs (G0/G1) progressed into the S phase, and the cell cycle progression was almost completely prevented in the presence of SP-60025. Our data suggest that JNK mediates the proliferative effect of ANG II in cultured HMCs and thus represents a novel therapeutic target for treatment of chronic renal diseases.

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Ca2+/calmodulin-dependent and cAMP-dependent kinases in induction of c-fos in human mesangial cells

AJP Renal Physiology ◽

10.1152/ajprenal.00074.2002 ◽

2002 ◽

Vol 283 (5) ◽

pp. F888-F894 ◽

Cited By ~ 5

Author(s):

Hong Zeng ◽

Ying Liu ◽

Douglas M. Templeton

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Mesangial Cells ◽

Camp Response Element Binding ◽

Renal Diseases ◽

Serum Starvation ◽

Early Event ◽

Rapid Decline ◽

Subsequent Increase ◽

Human Mesangial Cells

Mesangial cell proliferation is an early event in several progressive renal diseases. When mesangial cells in culture are rendered quiescent by serum starvation and subsequently stimulated to proliferate, induction of c- fos is an early indicator of entry into the cell cycle. Several heparin-sensitive signals transduce these events. We have examined the potential roles of CaMK and PKA. Selective stimulation of CaMK with Ca2+ ionophores and of PKA with forskolin or dibutyryl cAMP both result in induction of c- fos mRNA. CaMK but not PKA signaling is suppressed by low concentrations of heparin. Cross talk between the pathways has been demonstrated in some cells, with evidence of CaMK phosphorylating cAMP response element binding protein (CREB) at an inhibitory site and PKA suppressing CaMK-dependent signaling. However, in the present study, both pathways phosphorylated CREB on Ser133 and induced c- fosin an additive manner. Serum, ionomycin, and forskolin all caused a rapid decline in cyclin D1 levels, but only serum effected a subsequent increase, indicative of cell cycle progression. We conclude that, in human mesangial cells, CaMK and PKA can both contribute to cell cycle entry, and, although induction of c- fos by CaMK requires active PKA, neither pathway antagonizes or synergizes c- fosinduction by the other.

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Inflammatory Chemokine Expression via Toll-Like Receptor 3 Signaling in Normal Human Mesangial Cells

Clinical and Developmental Immunology ◽

10.1155/2013/984708 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 12

Author(s):

Hiroshi Tanaka ◽

Tadaatsu Imaizumi

Keyword(s):

Renal Disease ◽

Signaling Pathways ◽

Viral Infections ◽

Mesangial Cells ◽

Experimental Studies ◽

Renal Diseases ◽

Glomerular Diseases ◽

Human Mesangial Cells ◽

Normal Human ◽

Few Data

The innate and adaptive immune systems have been reported to play an important role in the pathogenesis of glomerular diseases. Since viral infections may trigger the development of inflammatory renal disease or the worsening of preexisting renal disease, recent studies have focused on the involvement of toll-like receptors (TLRs) and their signaling pathways in the inflammatory processes of glomerular cells. Viral double-stranded RNA (dsRNA) can activate not only TLR3 located within intracellular endosomes but also retinoic-acid-inducible-gene-I- (RIG-I-) like helicase receptors located within the cytosol. RIG-I and melanoma differentiation-associated gene 5 (MDA5) are members of the RNA helicase family in the cytosol, and both act as pathogen recognition receptors. The activation of TLRs and their downstream immune responses can be induced by both infectious pathogens and noninfectious stimuli such as endogenous ligands, and this mechanism may be involved in the pathogenesis of autoimmune renal diseases. However, there are few data on the interaction between TLR3, MDA5, and RIG-I in autoimmune glomerular diseases. Based on our recent experimental studies using cultured normal human mesangial cells (MCs), we found that novel TLR3-mediated signaling pathways in MCs may be involved in the pathogenesis of glomerular diseases. In the present paper, we summarize our recent findings.

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Collagen I upregulates extracellular matrix gene expression and secretion of TGF-β1 by cultured human mesangial cells

AJP Cell Physiology ◽

10.1152/ajpcell.00279.2003 ◽

2004 ◽

Vol 286 (6) ◽

pp. C1335-C1343 ◽

Cited By ~ 32

Author(s):

R. Ortega-Velazquez ◽

M. Gonzalez-Rubio ◽

M. P. Ruiz-Torres ◽

M. L. Diez-Marques ◽

M. C. Iglesias ◽

...

Keyword(s):

Extracellular Matrix ◽

Mrna Expression ◽

Blot Analysis ◽

Mesangial Cells ◽

Phenotypic Expression ◽

Renal Diseases ◽

Type I ◽

Human Mesangial Cells ◽

Matrix Gene ◽

Tgf Β1

Progressive renal diseases are characterized by an increased synthesis of extracellular matrix (ECM) components. The mechanisms involved in the development of these alterations are not completely known, but a crucial role for TGF-β1 has been suggested. Moreover, the ability of the ECM to modulate the phenotypic expression of different cell types has been widely described. In experiments presented here, human mesangial cells (HMC) were grown on collagen type I (COL I) or IV (COL IV). ECM protein and TGF-β1 mRNA expression were evaluated by Northern blot analysis, and TGF-β1 secretion was evaluated by ELISA. The involvement of tyrosine kinase and serine-threonine kinase pathways was studied by Western blot analysis, immunofluorescence, and in vitro kinase assays. HMC cultured on COL I showed an increased mRNA expression of COL I and COL IV, fibronectin, and TGF-β1. Both tyrosine phosphorylation and integrin-linked kinase (ILK) activity increased when HMC were cultured on COL I, and blockade of these pathways inhibited the increased secretion of TGF-β1. In conclusion, the present results support a role for extracellular COL I in the regulation of TGF-β1 synthesis during progressive renal sclerosis and fibrosis and the subsequent increase in newly synthesized ECM proteins. In addition, ILK, along with the tyrosine kinases, participates in the genesis of this effect.

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Prostacyclin Synthase: Upregulation during Renal Development and in Glomerular Disease as well as Its Constitutive Expression in Cultured Human Mesangial Cells

Mediators of Inflammation ◽

10.1155/2015/654151 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 3

Author(s):

Thomas Klein ◽

Günther Klaus ◽

Martin Kömhoff

Keyword(s):

Mesangial Cells ◽

Constitutive Expression ◽

Glomerular Disease ◽

Renal Diseases ◽

Prostaglandin E ◽

Human Mesangial Cells ◽

Immunoreactive Protein ◽

Peritubular Capillaries ◽

Prostacyclin Synthase

Prostacyclin (PGI2) plays a critical role in nephrogenesis and renal physiology. However, our understanding of how prostacyclin release in the kidney is regulated remains poorly defined. We studied expression of prostacyclin synthase (PGIS) in developing and adult human kidneys, and also in selected pediatric renal diseases. We also examined PGI2formation in human mesangial cellsin vitro. We observed abundant expression of PGIS in the nephrogenic cortex in humans andin situhybridization revealed an identical pattern in mice. In the normal adult kidney, PGIS-immunoreactive protein and mRNA appear to localize to mesangial fields and endothelial and smooth muscle cells of arteries and peritubular capillaries. In kidney biopsies taken from pediatric patients, enhanced expression of PGIS-immunoreactive protein was noted mainly in endothelial cells of patients with IgA-nephropathy. Cultured human mesangial cells produce primarily PGI2and prostaglandin E2, followed by prostaglandin F2αCytokine stimulation increased PGI2formation 24-fold. Under these conditions expression of PGIS mRNA and protein remained unaltered whereas mRNA for cyclooxygenase-2 was markedly induced. In contrast to its constitutive expressionin vitro, renal expression of prostacyclin-synthase appears to be regulated both during development and in glomerular disease. Further research is needed to identify the factors involved in regulation of PGIS-expression.

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