scholarly journals Stress granules are formed in renal proximal tubular cells during metabolic stress and ischemic injury for cell survival

2019 ◽  
Vol 317 (1) ◽  
pp. F116-F123 ◽  
Author(s):  
Shixuan Wang ◽  
Sang-Ho Kwon ◽  
Yunchao Su ◽  
Zheng Dong
Keyword(s):  
Rna Binding ◽  
Ischemia Reperfusion ◽  
Metabolic Stress ◽  
Stress Granules ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Short Period ◽  
Proximal Tubular ◽  
Renal Tubular

Stress granules (SGs) are a type of cytoplasmic structures formed in eukaryotic cells upon cell stress, which mainly contain RNA-binding proteins and RNAs. The formation of SGs is generally regarded as a mechanism for cells to survive a harsh insult. However, little is known about SG formation and function in kidneys. To address this, we applied different kinds of stressors to cultured proximal tubular cells as well as a short period of ischemia-reperfusion to mouse kidneys. It was found that glycolytic inhibitors such as 2-deoxy-d-glucose and 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one induced SG formation within 30 min in these cells. Similarly, SGs were induced by inhibitors of mitochondrial respiration such as sodium azide and CCCP. Renal ischemia-reperfusion induced SG formation in the cells of proximal tubules. To test the role of SGs, we stably knocked down G3bp1, a SG core protein, in renal tubular cells by shRNA viral transduction. As expected, knockdown of G3bp1 largely disrupted the assembly of SGs. After azide or cisplatin treatment, more dead cells were found in knockdown cells compared with controls, accompanied by increases in cleaved/active caspase-3. Reintroduction of exogenous G3bp1 into knockdown cells could rescue the cell death phenotype. Taken together, our data provide the first evidence of SG formation in renal tubular cells during metabolic stress and acute kidney injury. SGs are formed to protect proximal tubular cells under these conditions. Modulation of SG biogenesis may provide a novel approach to lessen the severity of renal diseases.

scholarly journals Palmitate aggravates proteinuria-induced cell death and inflammation via CD36-inflammasome axis in the proximal tubular cells of obese mice

2018 ◽  
Vol 315 (6) ◽  
pp. F1720-F1731 ◽  
Author(s):  
Lung-Chih Li ◽  
Jenq-Lin Yang ◽  
Wen-Chin Lee ◽  
Jin-Bor Chen ◽  
Chien-Te Lee ◽  
...  
Keyword(s):  
Cell Death ◽  
Tubular Injury ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Caspase 1 ◽  
Proximal Tubular ◽  
Renal Tubular ◽  
Nlrp3 Inflammasomes

High levels of serum free fatty acids (FFAs) and proteinuria have been implicated in the pathogenesis of obesity-related nephropathy. CD36, a class B scavenger receptor, is highly expressed in the renal proximal tubules and mediates FFA uptake. It is not clear whether FFA- and proteinuria-mediated CD36 activation coordinates NLRP3 inflammasomes to induce renal tubular injury and inflammation. In this study, we investigated the roles of CD36 and NLRP3 inflammasomes in FFA-induced renal injury in high-fat diet (HFD)-induced obesity. HFD-fed C57BL/6 mice and palmitate-treated HK2 renal tubular cells were used as in vivo and in vitro models. Immunohistochemical staining showed that CD36, IL-1β, and IL-18 levels increased progressively in the kidneys of HFD-fed mice. Sulfo- N-succinimidyl oleate (SSO), a CD36 inhibitor, attenuated the HFD-induced upregulation of NLRP3, IL-1β, and IL-18 and suppressed the colocalization of NLRP3 and ASC in renal tubular cells. In vitro, SSO abolished the palmitate-induced activation of IL-1β, IL-18, and caspase-1 in HK2 proximal tubular cells. Furthermore, treatment with SSO and the knockdown of caspase-1 expression by siRNA both inhibited palmitate-induced cell death and apoptosis in HK2 cells. Collectively, palmitate causes renal tubular inflammation, cell death, and apoptosis via the CD36/NLRP3/caspase-1 axis, which may explain, at least in part, the mechanism underlying FFA-related renal tubular injury. The blockade of CD36-induced cellular processes is therefore a promising strategy for treating obesity-related nephropathy.

scholarly journals Autophagy Deficiency in Renal Proximal Tubular Cells Leads to an Increase in Cellular Injury and Apoptosis under Normal Fed Conditions

2019 ◽  
Vol 21 (1) ◽  
pp. 155 ◽  
Author(s):  
Chigure Suzuki ◽  
Isei Tanida ◽  
Juan Alejandro Oliva Trejo ◽  
Soichiro Kakuta ◽  
Yasuo Uchiyama
Keyword(s):  
Renal Injury ◽  
Kidney Injury ◽  
Renal Tissue ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Proximal Tubular ◽  
Renal Proximal Tubular Cells ◽  
Renal Proximal Tubular ◽  
Renal Tubular

Renal proximal tubular epithelial cells are significantly damaged during acute kidney injury. Renal proximal tubular cell-specific autophagy-deficient mice show increased sensitivity against renal injury, while showing few pathological defects under normal fed conditions. Considering that autophagy protects the proximal tubular cells from acute renal injury, it is reasonable to assume that autophagy contributes to the maintenance of renal tubular cells under normal fed conditions. To clarify this possibility, we generated a knock out mouse model which lacks Atg7, a key autophagosome forming enzyme, in renal proximal tubular cells (Atg7flox/flox;KAP-Cre+). Analysis of renal tissue from two months old Atg7flox/flox;KAP-Cre+ mouse revealed an accumulation of LC3, binding protein p62/sequestosome 1 (a selective substrate for autophagy), and more interestingly, Kim-1, a biomarker for early kidney injury, in the renal proximal tubular cells under normal fed conditions. TUNEL (TdT-mediated dUTP Nick End Labeling)-positive cells were also detected in the autophagy-deficient renal tubular cells. Analysis of renal tissue from Atg7flox/flox;KAP-Cre+ mice at different age points showed that tubular cells positive for p62 and Kim-1 continually increase in number in an age-dependent manner. Ultrastructural analysis of tubular cells from Atg7flox/flox;KAP-Cre+ revealed the presence of intracellular inclusions and abnormal structures. These results indicated that autophagy-deficiency in the renal proximal epithelial tubular cells leads to an increase in injured cells in the kidney even under normal fed conditions.

scholarly journals Empagliflozin Ameliorates Free Fatty Acid Induced-Lipotoxicity in Renal Proximal Tubular Cells via the PPARγ/CD36 Pathway in Obese Mice

2021 ◽  
Vol 22 (22) ◽  
pp. 12408
Author(s):  
Chiang-Chi Huang ◽  
Chia-An Chou ◽  
Wei-Yu Chen ◽  
Jenq-Lin Yang ◽  
Wen-Chin Lee ◽  
...  
Keyword(s):  
Body Weight Gain ◽  
Specific Inhibitor ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Cd36 Expression ◽  
Proximal Tubular ◽  
Renal Proximal Tubular Cells ◽  
Renal Proximal Tubular ◽  
Renal Tubular

High serum levels of free fatty acids (FFAs) could contribute to obesity-induced nephropathy. CD36, a class B scavenger receptor, is a major receptor mediating FFA uptake in renal proximal tubular cells. Empagliflozin, a new anti-diabetic agent, is a specific inhibitor of sodium-glucose co-transporter 2 channels presented on renal proximal tubular cells and inhibits glucose reabsorption. In addition, empagliflozin has shown renoprotective effects. However, the mechanism through which empagliflozin regulates CD36 expression and attenuates FFA-induced lipotoxicity remains unclear. Herein, we aimed to elucidate the crosstalk between empagliflozin and CD36 in FFA-induced renal injury. C57BL/6 mice fed a high-fat diet (HFD) and palmitic acid-treated HK-2 renal tubular cells were used for in vivo and in vitro assessments. Empagliflozin attenuated HFD-induced body weight gain, insulin resistance, and inflammation in mice. In HFD-fed mice, CD36 was upregulated in the tubular area of the kidney, whereas empagliflozin attenuated CD36 expression. Furthermore, empagliflozin downregulated the expression of peroxisome proliferator-activated receptor (PPAR)-γ. Treatment with a PPARγ inhibitor (GW9662) did not further decrease PPARγ expression, whereas a PPARγ antagonist reversed this effect; this suggested that empagliflozin may, at least partly, decrease CD36 by modulating PPARγ. In conclusion, empagliflozin can ameliorate FFA-induced renal tubular injury via the PPARγ/CD36 pathway.

scholarly journals Lack of Cathepsin D in the Renal Proximal Tubular Cells Resulted in Increased Sensitivity against Renal Ischemia/Reperfusion Injury

2019 ◽  
Vol 20 (7) ◽  
pp. 1711 ◽  
Author(s):  
Chigure Suzuki ◽  
Isei Tanida ◽  
Masaki Ohmuraya ◽  
Juan Oliva Trejo ◽  
Soichiro Kakuta ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cathepsin D ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Tubular Epithelial Cells ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Proximal Tubular Cells ◽  
Renal Proximal Tubular

Cathepsin D is one of the major lysosomal aspartic proteases that is essential for the normal functioning of the autophagy-lysosomal system. In the kidney, cathepsin D is enriched in renal proximal tubular epithelial cells, and its levels increase during acute kidney injury. To investigate how cathepsin D-deficiency impacts renal proximal tubular cells, we employed a conditional knockout CtsDflox/−; Spink3Cre mouse. Immunohistochemical analyses using anti-cathepsin D antibody revealed that cathepsin D was significantly decreased in tubular epithelial cells of the cortico-medullary region, mainly in renal proximal tubular cells of this mouse. Cathepsin D-deficient renal proximal tubular cells showed an increase of microtubule-associated protein light chain 3 (LC3; a marker for autophagosome/autolysosome)-signals and an accumulation of abnormal autophagic structures. Renal ischemia/reperfusion injury resulted in an increase of early kidney injury marker, Kidney injury molecule 1 (Kim-1), in the cathepsin D-deficient renal tubular epithelial cells of the CtsDflox/−; Spink3Cre mouse. Inflammation marker was also increased in the cortico-medullary region of the CtsDflox/−; Spink3Cre mouse. Our results indicated that lack of cathepsin D in the renal tubular epithelial cells led to an increase of sensitivity against ischemia/reperfusion injury.

Prolactin and dopamine 1-like receptor interaction in renal proximal tubular cells

2010 ◽  
Vol 299 (1) ◽  
pp. F49-F54 ◽  
Author(s):  
Susanne Crambert ◽  
Agneta Sjöberg ◽  
Ann-Christine Eklöf ◽  
Fernando Ibarra ◽  
Ulla Holtbäck
Keyword(s):  
Protein Kinase ◽  
Atpase Activity ◽  
Proximal Tubular Cells ◽  
Dopamine System ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Proximal Tubular Cells ◽  
Renal Proximal Tubular ◽  
Renal Tubular ◽  
Renal Dopamine

Prolactin is a natriuretic hormone and acts by inhibiting the activity of renal tubular Na+-K+-ATPase activity. These effects require an intact renal dopamine system. Here, we have studied by which mechanism prolactin and dopamine interact in Sprague-Dawley rat renal tissue. Na+-K+-ATPase activity was measured as ouabain-sensitive ATP hydrolysis in microdissected renal proximal tubular segments. Intracellular signaling pathways were studied by a variety of different techniques, including Western blotting using phosphospecific antibodies, immunoprecipitation, and biotinylation assays. We found that dopamine and prolactin regulated Na+-K+-ATPase activity via similar signaling pathways, including protein kinase A, protein kinase C, and phosphoinositide 3-kinase activation. The cross talk between prolactin and dopamine 1-like receptors was explained by a heterologous recruitment of dopamine 1-like receptors to the plasma membrane in renal proximal tubular cells. Prolactin had no effect on Na+-K+-ATPase activity in spontaneously hypertensive rats, a rat strain with a blunted response to dopamine. These results further emphasize the central role of the renal dopamine system in the interactive regulation of renal tubular salt balance.

scholarly journals The exosomes derived from urine of premature infants target MAPK8 via miR-30a-5p to protect cisplatin-induced acute kidney injury in mice

2021 ◽  
Author(s):  
Mingming Ma ◽  
Qiao Luo ◽  
Lijing Fan ◽  
Weilong Li ◽  
Qiang Li ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Premature Infants ◽  
Target Genes ◽  
Kidney Injury ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Tubular ◽  
Hk2 Cells

Aim: Acute kidney injury (AKI), a global public health issue, not only causes millions of deaths every year, but is also a susceptible factor for chronic kidney disease (CKD). Nephrotoxic drugs are an important cause of AKI. There is still a lack of effective and satisfactory prevention method in clinical practice. This study investigated the protective effect of the exosomes derived from urine of premature infants on cisplatin-induced acute kidney injury. Methods: Isolation of exosomes from fresh urine of premature infants: The characteristics of exosomes were determined by flow cytometry, transmission electron microscopy and Western blotting. A C57BL/6 mice model of cisplatin-induced acute kidney injury was established. The mice in the experimental group were given 100ug exosomes dissolved in 200ul solution. The mice in the control group were given normal saline (200ul). These treatments were performed 24 hours after AKI was induced by intraperitoneal injection of cisplatin. To evaluate renal function, blood was drawn 24 hours after AKI model was established and serum creatinine (sCr) was measured. The mice were euthanized 72 hours after exosome treatment. The kidneys were collected for pathological examination, RNA and protein extraction, and the evaluation of renal tubular damage and apoptosis. In the in-vitro experiment, human renal cortex/proximal tubular cells (HK2) was induced by cisplatin to assess the protective ability of the exosomes derived from urine of premature infants. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western Blotting were used to evaluate the effect of exosomes treatment on the apoptosis of HK2 cells induced by cisplatin. Exosome microRNA sequencing technology and bioinformatics analysis method were applied to investigate the miRNAs enriched in exosomes and their target genes. The dual luciferase gene reporter system was used to detect the interaction of target genes. Results: Treatment of exosomes derived from urine of premature infants could decrease the level of serum creatinine and the apoptosis of renal tubular cell, inhibit the infiltration of inflammatory cell, protect mice from acute kidney injury induced by cisplatin and reduce mortality. In addition, miR-30a-5p was the most abundant miRNA in the exosomes derived from urine of premature infants. It protected HK2 cells from cisplatin-induced apoptosis by targeting and down-regulating the 3'UTR of mitogen-activated protein kinases (MAPK8) mRNA. Conclusions: According to our results, the exosomes derived from urine of premature infants alleviated cisplatin-induced acute kidney injury in mice and inhibited the apoptosis of human proximal tubular cells (HK2) induced by cisplatin in vitro. MiR-30a-5p in exosomes inhibited cisplatin-induced MAPK activation, ameliorated apoptosis, and protected renal function. The exosomes derived from urine of premature infants provided a promising acellular therapy for AKI.

scholarly journals PTEN alleviates maladaptive repair of renal tubular epithelial cells by restoring CHMP2A-mediated phagosome closure

2021 ◽  
Vol 12 (12) ◽  
Author(s):  
Huizhen Wang ◽  
Yifan Wang ◽  
Xin Wang ◽  
Huimi Huang ◽  
Jingfu Bao ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Renal Fibrosis ◽  
Cell Damage ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Mass Spectrometry Analysis ◽  
Acute Injury ◽  
Tubular Cells ◽  
Renal Tubular Cells ◽  
Renal Tubular

AbstractPhosphatase and Tensin Homolog on chromosome Ten (PTEN) has emerged as a key protein that governs the response to kidney injury. Notably, renal adaptive repair is important for preventing acute kidney injury (AKI) to chronic kidney disease (CKD) transition. To test the role of PTEN in renal repair after acute injury, we constructed a mouse model that overexpresses PTEN in renal proximal tubular cells (RPTC) by crossing PTENfl-stop-fl mice with Ggt1-Cre mice. Mass spectrometry-based proteomics was performed after subjecting these mice to ischemia/reperfusion (I/R). We found that PTEN was downregulated in renal tubular cells in mice and cultured HK-2 cells subjected to renal maladaptive repair induced by I/R. Renal expression of PTEN negatively correlated with NGAL and fibrotic markers. RPTC-specific PTEN overexpression relieved I/R-induced maladaptive repair, as indicated by alleviative tubular cell damage, apoptosis, and subsequent renal fibrosis. Mass spectrometry analysis revealed that differentially expressed proteins in RPTC-specific PTEN overexpression mice subjected to I/R were significantly enriched in phagosome, PI3K/Akt, and HIF-1 signaling pathway and found significant upregulation of CHMP2A, an autophagy-related protein. PTEN deficiency downregulated CHMP2A and inhibited phagosome closure and autolysosome formation, which aggravated cell injury and apoptosis after I/R. PTEN overexpression had the opposite effect. Notably, the beneficial effect of PTEN overexpression on autophagy flux and cell damage was abolished when CHMP2A was silenced. Collectively, our study suggests that PTEN relieved renal maladaptive repair in terms of cell damage, apoptosis, and renal fibrosis by upregulating CHMP2A-mediated phagosome closure, suggesting that PTEN/CHMP2A may serve as a novel therapeutic target for the AKI to CKD transition.

Abstract 210: Stem Cell Conditioned Culture Media Attenuated Albumin-induced Epithelial-mesenchymal Transition in Renal Tubular Cells

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Junping Hu ◽  
Weiqing Han ◽  
Qing Zhu ◽  
Pin-Lan Li ◽  
Ningjun Li
Keyword(s):  
Epithelial Mesenchymal Transition ◽  
Culture Media ◽  
Mesenchymal Transition ◽  
Tubular Cells ◽  
Protein Levels ◽  
Renal Tubular Cells ◽  
Proximal Tubular ◽  
Renal Proximal Tubular Cells ◽  
Renal Proximal Tubular ◽  
Renal Tubular

Mesenchymal stem cells (MSCs) have been shown to be a promising therapy for many different diseases. Stem cell conditioned culture media (SCM) exhibit similar beneficial effects as MSCs. Albuminuria-induced epithelial-mesenchymal transition (EMT) plays an important role in progressive renal tubulointerstitial fibrosis in chronic renal disease. The present study tested the hypothesis that SCM inhibit albumin-induced EMT in cultured renal tubular cells. SCM were obtained by culturing rat adult MSCs for 3 days. Cultured renal proximal tubular cells were incubated with rat albumin (20μg/ml) and treated with SCM or control culture media. Our results showed that 48 h albumin incubation stimulated EMT in renal proximal tubular cells as shown by significant decrease in the protein levels of epithelial marker E-cadherin from 2.30 ± 0.27 to 0.87 ± 0.11 ( P < 0.05) and increase in the protein levels of mesenchymal marker fibroblast-specific protein 1 (FSP-1) (2.18±0.33 folds, P < 0.05). SCM treatment significantly inhibited these albumin-induced changes in E-cadherin and FSP-1 by 2.33±0.17 and 1.95±0.23 folds ( P < 0.05), respectively. Meanwhile, albumin increased the mRNA levels of pro-inflammatory factor monocyte chemoattractant protein-1 (MCP)-1 by nearly 30 folds compared with control. SCM almost abolished the increase of MCP-1 induced by albumin. Furthermore, Western blot results displayed that albumin rapidly decreased the cytosolic levels and increased the nuclear levels of NF-κB, indicating a translocation of NF-κB; immunofluorescence microscopy also demonstrated that albumin induced NF-κB translocation from the cytosol into nucleus. SCM blocked the translocation of NF-κB into nucleus. These results suggest that SCM attenuated albumin-induced EMT in renal tubular cells via inhibiting NF-κB activation and inflammation, which may serve as a new therapeutic approach for chronic kidney diseases. (Supported by NIH grant HL89563 and HL106042)

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