scholarly journals Interplay between Akt and p38 MAPK pathways in the regulation of renal tubular cell apoptosis associated with diabetic nephropathy

2010 ◽  
Vol 298 (1) ◽  
pp. F49-F61 ◽  
Author(s):  
Madhavi J. Rane ◽  
Ye Song ◽  
Shunying Jin ◽  
Michelle T. Barati ◽  
Rui Wu ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
P38 Mapk ◽  
Caspase 3 ◽  
Tubular Cell ◽  
Renal Tubular Cell ◽  
Renal Tubules ◽  
Mapk Activation ◽  
Mapk Phosphorylation ◽  
Akt Phosphorylation ◽  
Akt Activation

Hyperglycemia induces p38 MAPK-mediated renal proximal tubular cell (RPTC) apoptosis. The current study hypothesized that alteration of the Akt signaling pathway by hyperglycemia may contribute to p38 MAPK activation and development of diabetic nephropathy. Immunoblot analysis demonstrated a hyperglycemia-induced increase in Akt phosphorylation in diabetic kidneys at 1 mo, peaking at 3 mo, and dropping back to baseline by 6 mo. Immunohistochemical staining with anti-pAkt antisera localized Akt phosphorylation to renal tubules. Maximal p38 MAPK phosphorylation was detected concomitant with increase in terminal uridine deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells and caspase-3 activity in 6-mo diabetic kidneys. Exposure of cultured RPTCs to high glucose (HG; 22.5 mM) significantly increased Akt phosphorylation at 3, 6, and 9 h, and decreased thereafter. In contrast, p38 MAPK phosphorylation was detected between 9 and 48 h of HG treatment. Increased p38 MAPK activation at 24 and 48 h coincided with increased apoptosis, demonstrated by increased caspase-3 activity at 24 h and increased TUNEL-positive cells at 48 h of HG exposure. Blockade of p38 cascade with SB203850 inhibited HG-induced caspase-3 activation and TUNEL-positive cells. Overexpression of constitutively active Akt abrogated HG-induced p38 MAPK phosphorylation and RPTC apoptosis. In addition, blockade of the phosphatidylinositol-3 kinase/Akt pathway with LY294002 and silencing of Akt expression with Akt small interfering RNA induced p38 MAPK phosphorylation in the absence of HG. These results collectively suggest that downregulation of Akt activation during long-term hyperglycemia contributes to enhanced p38 MAPK activation and RPTC apoptosis. Mechanism of downregulation of Akt activation in 6-mo streptozotocin diabetic kidneys was attributed to decreased Akt-heat shock protein (Hsp) 25, Akt-p38 interaction, and decreased PTEN activity. Thus PTEN or Hsp25 could serve as potential therapeutic targets to modulate Akt activation and control p38 MAPK-mediated diabetic complications.

Stimulation of pro-α1(I) collagen by TGF-β1 in mesangial cells: role of the p38 MAPK pathway

2001 ◽  
Vol 280 (3) ◽  
pp. F495-F504 ◽  
Author(s):  
Beek Yoke Chin ◽  
Amir Mohsenin ◽  
Su Xia Li ◽  
Augustine M. K. Choi ◽  
Mary E. Choi
Keyword(s):  
P38 Mapk ◽  
Intracellular Signaling ◽  
Mesangial Cells ◽  
Mapk Pathway ◽  
Dominant Negative ◽  
Glomerular Mesangial Cells ◽  
Mapk Activation ◽  
Mapk Phosphorylation ◽  
Collagen Mrna

Transforming growth factor-β1(TGF-β1) is a potent inducer of extracellular matrix protein synthesis and a key mediator of renal fibrosis. However, the intracellular signaling mechanisms by which TGF-β1stimulates this process remain incompletely understood. In this report, we examined the role of a major stress-activated intracellular signaling cascade, belonging to the mitogen-activated protein kinase (MAPK) superfamily, in mediating TGF-β1 responses in rat glomerular mesangial cells, using dominant-negative inhibition of TGF-β1 signaling receptors. We first stably transfected rat glomerular mesangial cells with a kinase-deleted mutant TGF-β type II receptor (TβR-IIM) designed to inhibit TGF-β1 signaling in a dominant-negative fashion. Next, expression of TβR-IIM mRNA was confirmed by Northern analysis. Cell surface expression and ligand binding of TβR-IIM protein were demonstrated by affinity cross-linking with 125I-labeled-TGF-β1. TGF-β1 rapidly induced p38 MAPK phosphorylation in wild-type and empty vector (pcDNA3)-transfected control mesangial cells. Interestingly, transfection with dominant-negative TβR-IIM failed to block TGF-β1-induced p38 MAPK phosphorylation. Moreover, dominant-negative TβR-IIMfailed to block TGF-β1-stimulated pro-α1(I) collagen mRNA expression and cellular protein synthesis, whereas TGF-β1-induced extracellular signal-regulated kinase (ERK) 1/ERK2 activation and antiproliferative responses were blocked by TβR-IIM. In the presence of a specific inhibitor of p38 MAPK, SB-203580, TGF-β1 was unable to stimulate pro-α1(I) collagen mRNA expression in the control and TβR-IIM-transfected mesangial cells. Finally, we confirmed that both p38 MAPK activation and pro-α1(I) collagen stimulation were TGF-β1 effects that were abrogated by dominant-negative inhibition of TGF-β type I receptor. Thus we show first demonstration of p38 MAPK activation by TGF-β1 in mesangial cells, and, given the rapid kinetics, this TGF-β1 effect is likely a direct one. Furthermore, our findings suggest that the p38 MAPK pathway functions as a component in the signaling of pro-α1(I) collagen induction by TGF-β1 in mesangial cells.

Ferroptosis involves in renal tubular cell death in diabetic nephropathy

2020 ◽  
Vol 888 ◽  
pp. 173574
Author(s):  
Yue Wang ◽  
Ran Bi ◽  
Fei Quan ◽  
Qiuhua Cao ◽  
Yanting Lin ◽  
...  
Keyword(s):  
Cell Death ◽  
Diabetic Nephropathy ◽  
Tubular Cell ◽  
Renal Tubular Cell ◽  
Renal Tubular

scholarly journals CXCR4 Promotes Renal Tubular Cell Survival in Male Diabetic Rats: Implications for Ligand Inactivation in the Human Kidney

Endocrinology ◽  
2015 ◽  
Vol 156 (3) ◽  
pp. 1121-1132 ◽  
Author(s):  
Ferhan S. Siddiqi ◽  
Li-Hao Chen ◽  
Suzanne L. Advani ◽  
Kerri Thai ◽  
Sri N. Batchu ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
Cell Survival ◽  
Cultured Cells ◽  
Human Kidney ◽  
Diabetic Rats ◽  
Cxcr4 Expression ◽  
Receptor Expression ◽  
Tubular Cell ◽  
Renal Tubular Cell ◽  
Tubulointerstitial Injury

Abstract Binding of the receptor CXCR4 to its ligand stromal cell–derived factor 1 (SDF-1) promotes cell survival and is under the influence of a number of regulatory processes including enzymatic ligand inactivation by endopeptidases such as matrix metalloproteinase 9 (MMP-9). In light of the pivotal role that the SDF-1/CXCR4 axis plays in renal development and in the pathological growth of renal cells, we explored the function of this pathway in diabetic rats and in biopsies from patients with diabetic nephropathy, hypothesizing that the pro-survival effects of CXCR4 in resident cells would attenuate renal injury. Renal CXCR4 expression was observed to be increased in diabetic rats, whereas antagonism of the receptor unmasked albuminuria and accelerated tubular epithelial cell death. In cultured cells, CXCR4 blockade promoted tubular cell apoptosis, up-regulated Bcl-2-associated death promoter, and prevented high glucose/SDF-1-augmented phosphorylation of the pro-survival kinase, Akt. Although CXCR4 expression was also increased in biopsy tissue from patients with diabetic nephropathy, serine 339 phosphorylation of the receptor, indicative of ligand engagement, was unaffected. Coincident with these changes in receptor expression but not activity, MMP-9 was also up-regulated in diabetic nephropathy biopsies. Supporting a ligand-inactivating effect of the endopeptidase, exposure of cultured cells to recombinant MMP-9 abrogated SDF-1 induced Akt phosphorylation. These observations demonstrate a potentially reno-protective role for CXCR4 in diabetes that is impeded in its actions in the human kidney by the coincident up-regulation of ligand-inactivating endopeptidases. Therapeutically intervening in this interplay may limit tubulointerstitial injury, the principal determinant of renal decline in diabetes.

scholarly journals Glucose-Dependent Insulinotropic Polypeptide Promotes β-(INS-1) Cell Survival via Cyclic Adenosine Monophosphate-Mediated Caspase-3 Inhibition and Regulation of p38 Mitogen-Activated Protein Kinase

Endocrinology ◽  
2003 ◽  
Vol 144 (10) ◽  
pp. 4433-4445 ◽  
Author(s):  
Jan A. Ehses ◽  
Vanbric R. Casilla ◽  
Tim Doty ◽  
J. Andrew Pospisilik ◽  
Kyle D. Winter ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cell Survival ◽  
Cell Fate ◽  
P38 Mapk ◽  
Caspase 3 ◽  
Glucose Deprivation ◽  
Adenosine Monophosphate ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Phosphorylation

The incretin glucose-dependent insulinotropic polypeptide (GIP) is a major regulator of postprandial insulin secretion in mammals. Recent studies in our laboratory, and others have suggested that GIP is a potent stimulus for protein kinase activation, including the MAPK (ERK1/2) module. Based on these studies, we hypothesized that GIP could regulate cell fate and sought to examine the underlying mechanisms involved in GIP stimulation of cell survival. GIP potentiated glucose-induced β-(INS-1)-cell growth to levels comparable with GH and GLP-1 while promoting cell survival in the face of serum and glucose-deprivation or treatment with wortmannin or streptozotocin. In the absence of GIP, 50% of cells died after 48 h of serum and glucose withdrawal, whereas 91 ± 10% of cells remained viable in the presence of GIP [n = 3, P < 0.05; EC50 of 1.24 ± 0.48 nm GIP (n = 4)]. Effects of GIP on cell survival and inhibition of caspase-3 were mimicked by forskolin, but pharmacological experiments excluded roles for MAPK kinase (Mek)1/2, phosphatidylinositol 3-kinase, protein kinase A, Epac, and Rap 1. Survival effects of GIP were ablated by the inhibitor SB202190, indicating a role for p38 MAPK. Furthermore, caspase-3 activity was also regulated by p38 MAPK, with a lesser role for Mek1/2, based on RNA interference studies. We propose that GIP is able to reverse caspase-3 activation via inhibition of long-term p38 MAPK phosphorylation in response to glucose deprivation (±wortmannin). Intriguingly, these findings contrasted with short-term phosphorylation of MKK3/6→p38 MAPK→ATF-2 by GIP. Thus, these data suggest that GIP is able to regulate INS-1 cell survival by dynamic control of p38 MAPK phosphorylation via cAMP signaling and lend further support to the notion that GIP regulation of MAPK signaling is critical for its regulation of cell fate.

Energy-dependent transport of digoxin across renal tubular cell monolayers (LLC-PK1)

1993 ◽  
Vol 71 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Shinya Ito ◽  
Gideon Koren ◽  
Patricia A. Harper ◽  
Melvin Silverman
Keyword(s):  
Maximum Velocity ◽  
Tubular Cell ◽  
Metabolic Inhibitors ◽  
Renal Tubular Cell ◽  
Renal Tubules ◽  
Cell Monolayers ◽  
P Glycoprotein ◽  
Apical Compartment ◽  
Renal Tubular ◽  
Energy Dependent

Digoxin secretory transport across renal tubular cell monolayers (LLC-PK1) grown on permeable filters was characterized. Metabolic inhibitors reduced total and specific basolateral to apical (B–A) flux of digoxin and conversely increased the apical to basolateral (A–B) flux. The specific transport of digoxin from the basolateral to the apical compartment was saturable, with a maximum velocity of transport of 184.5 ± 38.0 pmol∙cm−2∙h−1 and a Michaelis–Menten constant (Km) of 14.1 ± 1.6 μM. In addition, B–A flux of digoxin resulted in accumulation of digoxin in the apical compartment against the concentration gradient. P-Glycoprotein inhibitors such as quinidine, verapamil, vincristine, and cyclosporine increased the net A–B flux and inhibited the total B–A flux without affecting the nonspecific flux significantly. Tetraethylammonium, a prototype substrate for an organic cation transport system, had no such effect. Our results suggest that digoxin undergoes transepithelial secretion by an energy-dependent, carrier-mediated process in renal tubules, a process that seems to be distinct from the tetraethylammonium transport system.Key words: renal tubular secretion of digoxin, quinidine, tetraethylammonium, verapamil, vincristine, cyclosporine, P-glycoprotein.

scholarly journals Blockade of ERK1/2 by U0126 alleviates uric acid-induced EMT and tubular cell injury in rats with hyperuricemic nephropathy

2019 ◽  
Vol 316 (4) ◽  
pp. F660-F673 ◽  
Author(s):  
Min Tao ◽  
Yingfeng Shi ◽  
Lunxian Tang ◽  
Yi Wang ◽  
Lu Fang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Uric Acid ◽  
Signaling Pathways ◽  
Caspase 3 ◽  
Cellular Proliferation ◽  
Cell Injury ◽  
Tubular Cell ◽  
Matrix Metalloproteinase 2 ◽  
Renal Tubular Cell ◽  
Mesenchymal Transition

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are serine/threonine kinases and function as regulators of cellular proliferation and differentiation. Recently, we demonstrated that inhibition of ERK1/2 alleviates the development and progression of hyperuricemia nephropathy (HN). However, its potential roles in uric acid-induced tubular epithelial-mesenchymal transition (EMT) and tubular epithelial cell injury are unknown. In this study, we showed that hyperuricemic injury induced EMT as characterized by downregulation of E-cadherin and upregulation of vimentin and Snail1 in a rat model of HN. This was coincident with epithelial cells arrested at the G2/M phase of cell cycle, activation of Notch1/Jagged-1 and Wnt/β-catenin signaling pathways, and upregulation of matrix metalloproteinase-2 (MMP-2) and MMP-9. Administration of U0126, a selective inhibitor of ERK1/2, blocked all these responses. U0126 was also effective in inhibiting renal tubular cell injury, as shown by decreased expression of lipocalin-2 and kidney injury molecule-1 and active forms of caspase-3. U0126 or ERK1/2 siRNA can inhibit tubular cell EMT and cell apoptosis as characterized with decreased expression of cleaved caspase-3. Moreover, ERK1/2 inhibition suppressed hyperuricemic injury-induced oxidative stress as indicated by decreased malondialdehyde and increased superoxide dismutase. Collectively, ERK1/2 inhibition-elicited renal protection is associated with inhibition of EMT through inactivation of multiple signaling pathways and matrix metalloproteinases, as well as attenuation of renal tubule injury by enhancing cellular resistance to oxidative stress.

scholarly journals The Role of TLR4 on PGC-1α-Mediated Oxidative Stress in Tubular Cell in Diabetic Kidney Disease

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Shuguang Yuan ◽  
Xuemei Liu ◽  
Xuejing Zhu ◽  
Zhong Qu ◽  
Zailiang Gong ◽  
...  
Keyword(s):  
Kidney Disease ◽  
Cytochrome C ◽  
Oxidative Damage ◽  
Mitochondrial Dysfunction ◽  
Diabetic Kidney Disease ◽  
Caspase 3 ◽  
Tubular Cell ◽  
Renal Tubules ◽  
Diabetic Mice ◽  
Diabetic Kidney

The role and precise mechanism of TLR4 in mitochondria-related oxidative damage and apoptosis of renal tubules in diabetic kidney disease (DKD) remain unclear. We examined the expression of TLR4 in renal biopsy tissues. Db/db diabetic mice and HK-2 cells cultured under high glucose (HG) were used as in vivo and vitro models. Real-time RT-PCR, Western blot, and immunohistochemistry were performed to examine the mRNA and protein levels of TLR4, NF-κΒ, PGC-1α, cytochrome C, and cleaved caspase-3. ATP level, activity of electron transport chain complex III, and antioxidant enzymes were investigated for mitochondrial function. Electron microscopy (EM) and MitoTracker Red CMXRos were used for mitochondrial morphology alteration. DHE staining and TUNEL assay were detected for ROS accumulation and apoptosis. PGC-1α plasmids were used for the overexpression of PGC-1α in HK-2. TAK242 and parthenolide were used as TLR4 and NF-κB blockers, respectively. Results showed that TLR4 was extensively expressed in the renal tubules of DKD patients and db/db diabetic mice, which was positively related to the tubular interstitial damage score and urinary β-NAG levels. In diabetic mice, inhibition of TLR4 could reverse the decreased expression of PGC-1α, increased expression of cytochrome C and cleaved caspase-3, mitochondrial dysfunction and deformation, increased accumulation of ROS, and activation of tubular cell apoptosis. In vitro, inhibition of TLR4 or NF-κB showed consistent results. PGC-1α overexpression could reverse the mitochondrial dysfunction, increased cleaved caspase-3, and apoptosis in HK-2 cells treated with HG. Data indicated that the TLR4/NF-κB signaling pathway might be the upstream pathway of PGC-1α and promote the tubular damage of DKD by modulating the mitochondria-related oxidative damage and apoptosis.

scholarly journals NIX-mediated mitophagy protects against proteinuria-induced tubular cell apoptosis and renal injury

2019 ◽  
Vol 316 (2) ◽  
pp. F382-F395 ◽  
Author(s):  
Dan Xu ◽  
Panpan Chen ◽  
Bao Wang ◽  
Yanzhe Wang ◽  
Naijun Miao ◽  
...  
Keyword(s):  
Renal Injury ◽  
Cell Apoptosis ◽  
Cell Injury ◽  
Kidney Injury ◽  
Underlying Mechanism ◽  
Tubular Cell ◽  
Renal Tubular Cell ◽  
Common Symptom ◽  
Renal Tubules ◽  
Renal Tubular

Proteinuria, the most common symptom of renal injury, is an independent factor for renal tubular injury. However, the underlying mechanism remains to be fully elucidated. Mitochondrion is an important target for proteinuria-induced renal tubular cell injury. Insufficient mitophagy exacerbates cell injury by initiating mitochondrial dysfunction-related cell apoptosis. In the experiment, the role of NIP3-like protein X (NIX)-mediated mitophagy was investigated in proteinuria-induced renal injury. In this study, we demonstrated that NIX expression was reduced in renal tubules and correlated with the decline of estimated glomerular filtration rate and increase of the proteinuria in patients. In proteinuric mice, NIX-mediated mitophagy was significantly suppressed. Meanwhile, the proteinuric mice exhibited renal dysfunction, increased mitochondrial fragmentation, and tubular cell apoptosis. Overexpression of NIX attenuated those disruptions in proteinuric mice. In cultured renal tubular epithelial cells, albumin induced a decrease in NIX-mediated mitophagy and an increase in cell apoptosis. Overexpression of NIX attenuated albumin-induced cell apoptosis, whereas NIX siRNA aggravated these perturbations. These results indicate that proteinuria suppresses NIX-mediated mitophagy in the renal tubular epithelial cell, which triggers the cell undergoing mitochondria-dependent cell apoptosis. Collectively, our finding suggests that restoration of NIX-mediated mitophagy might be a novel therapeutic target for alleviating proteinuria-induced kidney injury.

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