scholarly journals Jak2-Independent Activation of Stat3 by Intracellular Angiotensin II in Human Mesangial Cells

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Rekha Singh
Keyword(s):  
Transcription Factor ◽  
High Glucose ◽  
Mesangial Cells ◽  
Binding Activity ◽  
Matrix Proteins ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Human Mesangial Cells ◽  
Stat3 Transcription Factor ◽  
Stat3 Phosphorylation

Ang II is shown to mediate the stimulatory effect of high glucose on TGF-b1 and extracellular matrix proteins in glomerular mesangial cells. Also inhibition of Ang II formation in cell media (extracellular) and lysates (intracellular) blocks high-glucose effects on TGF-b1 and matrix more effectively compared to inhibition of extracellular Ang II alone. To investigate whether intracellular Ang II can stimulate TGF-b1 and matrix independent of extracellular Ang II, cultured human mesangial cells were transfected with Ang II to increase intracellular Ang II levels and its effects on TGF-b1 and matrix proteins were determined. Prior to transfection, cells were treated with candesartan to block extracellular Ang II-induced responses via cell membrane AT1 receptors. Transfection of cells with Ang II resulted in increased levels of intracellular Ang II which was accompanied by increased production of TGF-b1, collagen IV, fibronectin, and cell proliferation as well. On further examination, intracellular Ang II was found to activate Stat3 transcription factor including increased Stat3 protein expression, tyrosine 705 phosphorylation, and DNA-binding activity. Treatment with AG-490, an inhibitor of Jak2, did not block intracellular Ang II-induced Stat3 phosphorylation at tyrosine 705 residue indicating a Jak2-independent mechanism used by intracellular Ang II for Stat3 phosphorylation. In contrast, extracellular Ang II-induced tyrosine 705 phosphorylation of Stat3 was inhibited by AG-490 confirming the presence of a Jak2-dependent pathway. These findings suggest that intracellular Ang II increases TGF-b1 and matrix in human mesangial cells and also activates Stat3 transcription factor without involvement of the extracellular Ang II signaling pathway.

Increased extracellular matrix synthesis and mRNA in mesangial cells grown in high-glucose medium

1991 ◽  
Vol 260 (2) ◽  
pp. F185-F191 ◽  
Author(s):  
S. H. Ayo ◽  
R. A. Radnik ◽  
W. F. Glass ◽  
J. A. Garoni ◽  
E. R. Rampt ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Protein Synthesis ◽  
High Glucose ◽  
Mesangial Cells ◽  
Matrix Proteins ◽  
Cell Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mrna Levels ◽  
Glomerular Mesangial Cells ◽  
Glomerular Mesangium

Nodular expansion of glomerular mesangium with increased amounts of extracellular matrix (ECM) material is pathognomic of diabetic nephropathy. The precise mechanisms involved in this accumulation are unknown. Recently, we reported using a solid-phase enzyme-linked immunosorbent assay (ELISA) technique that glomerular mesangial cells, the principal cell type residing in glomerular mesangium, accumulate 50–60% more fibronectin (FN), laminin (LM), and type IV collagen (T-IV) when cultured in medium containing high glucose (30 mM) (S. H. Ayo, R. A. Rodnik, J. Garoni, W. F. Glass II, and J. I. Kreiberg. Am. J. Pathol. 136: 1339-1348, 1990). ECM assembly is controlled by its rate of synthesis and degradation, as well as its binding and rate of incorporation into the ECM. To elucidate the mechanisms involved, pulse-chase experiments were designed to estimate ECM protein synthesis from the incorporation of Trans-35S [( 35S]methionine, [35S]cysteine) into immunoprecipitated FN, LM, and T-IV. mRNA levels were examined, and degradation rates were estimated from the disappearance of radioactivity from matrix proteins in mesangial cells previously incubated with Trans-35S. One week of growth in 30 mM glucose resulted in approximately 40–50% increase in the synthesis of all three matrix proteins compared with 10 mM glucose-grown cells. This was accompanied by a significant increase in the transcripts for all three matrix proteins (approximately twofold). The specific activity of the radiolabel in trichloroacetic acid-precipitable cell protein showed no difference between cells grown in 10 or 30 mM glucose, indicating that total protein synthesis was unchanged. After 1 wk, the rate of FN, LM, and T-IV collagen degradation was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

High glucose induces the activity and expression of Na+/H+exchange in glomerular mesangial cells

2000 ◽  
Vol 278 (1) ◽  
pp. F91-F96 ◽  
Author(s):  
Michael B. Ganz ◽  
Karen Hawkins ◽  
Robert F. Reilly
Keyword(s):  
Steady State ◽  
High Glucose ◽  
Prolonged Exposure ◽  
Mesangial Cells ◽  
Fold Increase ◽  
Cell Behavior ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Exchange Contribution ◽  
Acid Extrusion

.—Changes in activity or expression of transporters may account for alterations in cell behavior in diabetes. We sought to ascertain if mesangial cells (MC) grown in different glucose concentrations exhibit changes in activity and expression of acid-extruding transporters, the Na+/H+and Na+-dependent Cl−/[Formula: see text]exchanger. pHi was determined by the use of the fluorescent pH-sensitive dye BCECF. In MCs grown in 5 mM glucose (control), the Na+/H+exchanger was responsible for 31.8 ± 5.1% of steady-state pHi, whereas Na+-dependent Cl−/[Formula: see text]contributed 62.9 ± 4.0% ( n = 11). In MCs grown in high glucose for 2 wk, Na+/H+exchange contribution to acid-extrusion increased as follows: 42.3 ± 4.6% [ n = 8, 10 mM, not significant (NS)], 51.1 ± 5.1% ( n = 8, 20 mM, P < 0.01), and 64.8 ± 5.5% ( n = 7, 30 mM, P < 0.001). The Na+-dependent Cl−/[Formula: see text]exchanger contributed less [47.0 ± 4.6, 38.6 ± 5.8, and 21.1 ± 3.8%, for 10, 20, and 30 mM glucose, respectively ( n > 7)]. We sought to ascertain if the magnitude of the acute stimulated response to ANG II by the Na+/H+and Na+-dependent Cl−/[Formula: see text]exchanger is changed. Na+/H+exchanger (1.89-fold increase in 30 vs. 5 mM, P < 0.002), but not Na+-dependent Cl−/[Formula: see text]exchange (0.17-fold, NS), exhibited an enhanced response to ANG II (1 μM). Na+/H+exchange (NHE1) expression was significantly different (1.72-fold) after prolonged exposure to high glucose. These results suggest that the Na+/H+exchanger, but not Na+-dependent Cl−/[Formula: see text]exchanger, may play an early role in the response to hyperglycemia in the diabetic state.

Downregulation of TRPC6 protein expression by high glucose, a possible mechanism for the impaired Ca2+ signaling in glomerular mesangial cells in diabetes

2007 ◽  
Vol 293 (4) ◽  
pp. F1381-F1390 ◽  
Author(s):  
Sarabeth Graham ◽  
Min Ding ◽  
Sherry Sours-Brothers ◽  
Thomas Yorio ◽  
Jian-Xing Ma ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Protein Expression ◽  
High Glucose ◽  
Mesangial Cells ◽  
Membrane Currents ◽  
Maximum Effect ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Fura 2 ◽  
Fluorescence Measurements

The present study was performed to investigate whether transient receptor potential (TRPC)6 participated in Ca2+ signaling of glomerular mesangial cells (MCs) and expression of this protein was altered in diabetes. Western blots and real-time PCR were used to evaluate the expression level of TRPC6 protein and mRNA, respectively. Cell-attached patch-clamp and fura-2 fluorescence measurements were utilized to assess angiotensin II (ANG II)-stimulated membrane currents and Ca2+ responses in MCs. In cultured human MCs, high glucose significantly reduced expression of TRPC6 protein, but there was no effect on either TRPC1 or TRPC3. The high glucose-induced effect on TRPC6 was time and dose dependent with the maximum effect observed on day 7 and at 30 mM glucose, respectively. In glomeruli isolated from streptozotocin-induced diabetic rats, TRPC6, but not TRPC1, was markedly reduced compared with the glomeruli of control rats. Furthermore, TRPC6 mRNA in MCs was also significantly decreased by high glucose as early as 1 day after treatment with maximal reduction on day 4. Patch-clamp experiments showed that ANG II-stimulated membrane currents in MCs were significantly attenuated or enhanced by knockdown or overexpression of TRPC6, respectively. Fura-2 fluorescence measurements revealed that the ANG II-induced Ca2+ influxes were markedly inhibited in MCs with TRPC6 knockdown, reminiscent of the impaired Ca2+ entry in response to ANG II in high glucose-treated MCs. These results suggest that the TRPC6 protein expression in MCs was downregulated by high glucose and the deficiency of TRPC6 protein might contribute to the impaired Ca2+ signaling of MCs seen in diabetes.

Role of the JAK/STAT signaling pathway in diabetic nephropathy

2006 ◽  
Vol 290 (4) ◽  
pp. F762-F768 ◽  
Author(s):  
Mario B. Marrero ◽  
Amy K. Banes-Berceli ◽  
David M. Stern ◽  
Douglas C. Eaton
Keyword(s):  
Diabetic Nephropathy ◽  
High Glucose ◽  
Intracellular Signaling ◽  
Mesangial Cells ◽  
Janus Kinase ◽  
Cellular Growth ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Stat Signaling ◽  
Vasoactive Peptide

Excessive cellular growth is a major contributor to pathological changes associated with diabetic nephropathy. In particular, high glucose-induced growth of glomerular mesangial cells is a characteristic feature of diabetes-induced renal complications. Glomerular mesangial cells respond to traditional growth factors, although in diabetes this occurs in the context of an environment enriched in both circulating vasoactive mediators and high glucose. For example, the vasoactive peptide ANG II has been implicated in the pathogenesis of diabetic renal disease, and recent findings suggest that high glucose and ANG II activate intracellular signaling processes, including the polyol pathway and generation of reactive oxygen species. These pathways activate the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling cascades in glomerular mesangial cells. Activation of the JAK/STAT signaling cascade can stimulate excessive proliferation and growth of glomerular mesangial cells, contributing to diabetic nephropathy. This review focuses on some of the key elements in the diabetic microenvironment, especially high glucose and the accumulation of advanced glycoxidation end products and considers their impact on ANG II and other vasoactive peptide-mediated signaling events in vitro and in vivo.

Vasoconstrictor-evoked prostaglandin synthesis in cultured human mesangial cells

1985 ◽  
Vol 248 (2) ◽  
pp. F240-F246 ◽  
Author(s):  
N. Ardaillou ◽  
J. Hagege ◽  
M. P. Nivez ◽  
R. Ardaillou ◽  
D. Schlondorff
Keyword(s):  
Arginine Vasopressin ◽  
Mesangial Cells ◽  
Platelet Activating Factor ◽  
Feedback Mechanism ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Human Mesangial Cells ◽  
Cell Contractility ◽  
Human Glomerular Mesangial Cells ◽  
Cells Cultured

We examined the influence of angiotensin II (ANG II), arginine vasopressin (AVP), and platelet activating factor (PAF) on prostaglandin (PG) synthesis and cell contractility in human glomerular mesangial cells in culture. Addition of sodium butyrate to the culture medium for 40 h significantly increased synthesis of both 6-keto-PGF1 alpha and PGE2 in the presence of exogenous arachidonic acid and of PGE2 under basal conditions. To optimize conditions in all further experiments, cells cultured with butyrate were studied. Under basal conditions, cultured mesangial cells produced predominantly 6-keto-PGF1 alpha and much less PGE2. Addition of either ANG II, AVP, or PAF all resulted in a rapid (within minutes) two- to threefold stimulation of 6-keto-PGF1 alpha and PGE2. Threshold stimulations were obtained at 10 pM for ANG II, 1 nM for AVP, and 10-100 pM for PAF. Preincubation of the cells with [Sar1,Ala8]ANG II, an antagonist of ANG II, inhibited ANG II-enhanced PG production, and preincubation with 1-desamino-8-D-arginine vasopressin, an antidiuretic analogue, blunted AVP-enhanced PG production. Under phase-contrast microscopy, PAF, ANG II, and, to a lesser degree, AVP caused decrease in cell surface area of mesangial cells cultured without butyrate at concentrations similar to those stimulating PG synthesis. Only PAF contracted cells cultured with butyrate, indicating attenuation of the vasoactive effects of ANG II and AVP when synthesis of PG was increased. However, a lower dose of PAF was only active when PG synthesis was inhibited, suggesting the same feedback mechanism for the three agonists.

scholarly journals Impairment of hepatic nuclear factor-4α binding to the Stim1 promoter contributes to high glucose-induced upregulation of STIM1 expression in glomerular mesangial cells

2015 ◽  
Vol 308 (10) ◽  
pp. F1135-F1145 ◽  
Author(s):  
Yanxia Wang ◽  
Sarika Chaudhari ◽  
Yuezhong Ren ◽  
Rong Ma
Keyword(s):  
Protein Expression ◽  
High Glucose ◽  
Mesangial Cells ◽  
Therapeutic Option ◽  
Binding Activity ◽  
Nuclear Factor ◽  
Glomerular Mesangial Cells ◽  
Expression Levels ◽  
293 Cells ◽  
Interfering Rna

The present study was carried out to investigate if hepatic nuclear factor (HNF)4α contributed to the high glucose-induced increase in stromal interacting molecule (STIM)1 protein abundance in glomerular mesangial cells (MCs). Western blot and immunofluorescence experiments showed HNF4α expression in MCs. Knockdown of HNF4α using a small interfering RNA approach significantly increased mRNA expression levels of both STIM1 and Orai1 and protein expression levels of STIM1 in cultured human MCs. Consistently, overexpression of HNF4α reduced expressed STIM1 protein expression in human embryonic kidney-293 cells. Furthermore, high glucose treatment did not significantly change the abundance of HNF4α protein in MCs but significantly attenuated HNF4α binding activity to the Stim1 promoter. Moreover, knockdown of HNF4α significantly augmented store-operated Ca2+ entry, which is known to be gated by STIM1 and has recently been found to be antifibrotic in MCs. In agreement with those results, knockdown of HNF4α significantly attenuated the fibrotic response of high glucose. These results suggest that HNF4α negatively regulates STIM1 transcription in MCs. High glucose increases STIM1 expression levels by impairing HNF4α binding activity to the Stim1 promoter, which subsequently releases Stim1 transcription from HNF4α repression. Since the STIM1-gated store-operated Ca2+ entry pathway in MCs has an antifibrotic effect, inhibition of HNF4α in MCs might be a potential therapeutic option for diabetic kidney disease.

Extracellular glucose reduces the responsiveness of mesangial cell ion channels to angiotensin II

1995 ◽  
Vol 269 (3) ◽  
pp. F389-F397 ◽  
Author(s):  
E. E. Seal ◽  
D. C. Eaton ◽  
L. M. Gomez ◽  
H. Ma ◽  
B. N. Ling
Keyword(s):  
Angiotensin Ii ◽  
Ion Channels ◽  
High Glucose ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Ion Homeostasis ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Extracellular Glucose ◽  
Normal Glucose

Abnormal cellular ion homeostasis is a well-recognized component of diabetic glomerular disease. In cultured rat glomerular mesangial cells, we have previously shown that insulin regulates Ca(2+)-dependent activation of 4-pS Cl- channels and 27-pS nonselective cation channels (NSCC) by angiotensin II (ANG II). To assess whether extracellular glucose also affects mesangial ion channels, we applied patch-clamp techniques to cells incubated in constant insulin (100 mU/ml) and either "normal" (5 mM) or "high" (30 mM) glucose for 1 wk. In normal glucose, 100 nM ANG II increased Cl- and NSCC activity by > 16-fold and > 60-fold, respectivley. Direct release of intracellular Ca2+ ([Ca2+]i) stores (0.25 microM thapsigargin) mimicked ANG II-induced channel stimulation. In high glucose, Cl- and NSCC stimulation by ANG II was attenuated (< 7-fold), whereas channel activation by thapsigargin was unaffected. Protein kinase C (PKC) inhibition (30-min exposure to 0.5 microM calphostin) or downregulation (24-h exposure to 0.1 microM 4 beta-phorbol 12-myristate 13-acetate), but not aldose reductase inhibition (0.5 mM sorbinil), restored channel responsiveness to ANG II despite high glucose. Channel responsiveness was also restored if mesangial cells were coincubated in both high glucose and 500 microM myo-inositol. Acute exposure to a synthetic diacylglycerol (100 microM 1-oleoyl-2-acetyl glycerol) reestablished channel unresponsiveness to ANG II. We conclude the following in rat mesangial cell cultures: 1) Activation of Ca(2+)-dependent Cl- and NSCCs by ANG II is reduced by high extracellular glucose.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of high glucose on gene expression in mesangial cells: upregulation of the thiol pathway is an adaptational response

2004 ◽  
Vol 17 (3) ◽  
pp. 271-282 ◽  
Author(s):  
Jolean Morrison ◽  
Kristen Knoll ◽  
Martin J. Hessner ◽  
Mingyu Liang
Keyword(s):  
Lipid Peroxidation ◽  
Mrna Expression ◽  
High Glucose ◽  
Molecular Mechanisms ◽  
Mesangial Cells ◽  
Critical Role ◽  
Glomerular Mesangial Cells ◽  
Human Mesangial Cells ◽  
Stage Renal Disease ◽  
End Stage

Pathological alterations in glomerular mesangial cells play a critical role in the development of diabetic nephropathy, the leading cause of end-stage renal disease. Molecular mechanisms mediating such alterations, however, remain to be fully understood. The present study first examined the effect of high glucose on the mRNA expression profile in rat mesangial cells using cDNA microarray. Based on variation-weighted criteria and with a false discovery rate of 4.3%, 459 of 17,664 cDNA elements examined were found to be upregulated and 151 downregulated by exposure to 25 mM d-glucose for 5 days. A large number of differentially expressed genes belonged to several functional categories, indicating high glucose had a profound effect on mesangial cell proliferation, protein synthesis, energy metabolism, and, somewhat unexpectedly, protein sorting and the cytoskeleton. Interestingly, several thiol antioxidative genes (glutathione peroxidase 1, peroxiredoxin 6, and thioredoxin 2) were found by microarray and confirmed by real-time PCR to be upregulated by high glucose. These changes suggested that the oxidative stress known to be induced in mesangial cells by high glucose might be buffered by upregulation of the thiol antioxidative pathway. Upregulation of thiol antioxidative genes also occurred in high-glucose-treated human mesangial cells and in glomeruli isolated from rats after 1 wk of streptozotocin-induced diabetes, but not in human proximal tubule cells. High glucose slightly increased lipid peroxidation and decreased the amount of reduced thiols in rat and human mesangial cells. Disruption of the thiol antioxidative pathway by two different thiol-oxidizing agents resulted in a three- to fivefold increase in high-glucose-induced lipid peroxidation. In summary, the present study provided a global view of the short-term effect of high glucose on mesangial cells at the level of mRNA expression and identified the upregulation of the thiol antioxidative pathway as an adaptational response of mesangial cells to high glucose.

scholarly journals LncRNA NNT-AS1 regulates proliferation, ECM accumulation and inflammation of human mesangial cells induced by high glucose through miR-214-5p/smad4

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhuang Geng ◽  
Xiang Wang ◽  
Shiyuan Hao ◽  
Bingzi Dong ◽  
Yajing Huang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Diabetic Nephropathy ◽  
Mirna Target ◽  
Molecular Mechanisms ◽  
Mesangial Cells ◽  
Luciferase Reporter ◽  
Glomerular Mesangial Cells ◽  
Human Mesangial Cells ◽  
Quantitative Expression ◽  
Potential Biomarker

Abstract Background LncRNA NNT-AS1 (NNT-AS1) has been extensively studied as the causative agent in propagation and progression of lung and bladder cancers, and cholangiocarcinoma. However, its significance in proliferation and inflammation of diabetic nephropathy is enigmatic. This study focuses on the molecular mechanisms followed by NNT-AS1 to establish diabetic nephropathy (DN) and its potential miRNA target. Methods Bioinformatics analysis to identify potential miRNA target of NNT-AS1 and smad4 transcription factor was conducted using LncBase and TargetScan, and was subsequently confirmed by luciferase reporter assay. Relative quantitative expression of NNT-AS1 in human glomerular mesangial cells (HGMCs) was detected through quantitative real-time PCR and WB analysis. Cell proliferation was detected through CCK-8 assay, whereas, ELISA was conducted to evaluate the expression of inflammatory cytokines. Following this, relative expression of miR-214-5p and smad4 were confirmed through qRT-PCR and western blot analysis. Results Results from the experiments manifested up-regulated levels of NNT-AS1 and smad4 in the blood samples of DN patients as well as in HGMCs, whereas, downregulated levels of miR-214-5p were measured in the HGMCs suggesting the negative correlation between NNT-AS1 and miR-214-5p. Potential binding sites of NNT-AS1 showed miR-214-5p as its direct target and NNT-AS1 as potential absorber for this microRNA, in turn increasing the expression of transcription factor smad4. Conclusion The data suggests that NNT-AS1 can be positively used as a potential biomarker and indicator of DN and causes extracellular matrix (ECM) accumulation and inflammation of human mesangial cells.

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