Tubular Cell Apoptosis Research Articles

PKNOX2 regulates myofibroblast functions and tubular cell survival during kidney fibrosis

The number of patients with chronic kidney disease (CKD) is increasing worldwide. When kidneys are exposed to severe injury, tubular cell death occurs and kidney fibrosis progresses by activating fibroblasts and myofibroblasts (referred to as (myo)fibroblasts), leading to CKD; however, the pathological and molecular mechanisms underlying CKD, including kidney fibrosis, remain obscure. In the present study, we focused on a transcription factor PBX/Knotted Homeobox 2 (PKNOX2) in kidney fibrosis. The transcript and protein expression of PKNOX2 was upregulated in fibrotic kidneys after unilateral ureteral obstruction (UUO). Importantly, immunofluorescence microscopic analysis revealed that the number of PKNOX2-expressing myofibroblasts was increased, whereas the expression of PKNOX2 was decreased in proximal tubular epithelial cells after UUO. In (myo)fibroblasts, PKNOX2 was induced by TGF-β1. Knockdown of PKNOX2 using shRNA lentiviral system reduced the viability of (myo)fibroblasts either in the presence or absence of TGF-β1, accompanied by increased apoptosis. Moreover, PKNOX2 knockdown decreased TGF-β1-induced migration of myofibroblasts and differentiation of fibroblasts into myofibroblasts. Significantly, knockdown of PKNOX2 also decreased the viability and increased apoptosis of tubular epithelial cells. Collectively, PKNOX2 regulates the function of (myo)fibroblasts and the viability of proximal tubular epithelial cells in progression of kidney fibrosis.

MicroRNA‑93 inhibits the apoptosis and inflammatory response of tubular epithelial cells via the PTEN/AKT/mTOR pathway in acute kidney injury.

Renal tubular epithelial cell injury is the main cause of septic acute kidney injury (AKI), which is characterized by the excessive inflammatory response and apoptosis. Numerous studies have demonstrated that miRNAs are associated with inflammatory response and apoptosis in numerous diseases. The present study mainly focuses on investigating the association between microRNA (miRNA/miR) expression and inflammatory response and apoptosis in the pathogenesis of AKI. In vitro and in vivo models of AKI were simulated using Escherichia coli lipopolysaccharide (LPS)-administrated kidney epithelial cells and mice, respectively. The miRNA expression profile was examined using miRNA microarray in kidney tissues. Next, the effects of miR-93 upregulation on the apoptosis, cytokine expression and oxidative stress in the LPS-stimulated TCMK-1 were tested. The target genes of this miRNA were investigated, and the regulatory association between miR-93 and the AKT/mTOR pathway was investigated. The results demonstrated that miR-93 was the most downregulated miRNA in mice kidney. Furthermore, in LPS-induced renal tubular epithelial cells (TECs) injury model, that upregulation of miR-93 was found to attenuate the apoptosis and inflammatory response, as well as reactive oxygen species generation. Mechanistically, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) was identified as a target of miR-93. Further experiments revealed that LPS-induced the decrease of phosphorylated (p)-AKT and p-mTOR protein expression in vitro are reversed by the overexpression of miR-93. The results of the present study suggested that the protective effect of miR-93 on AKI may be associated with the activation of PTEN/AKT/mTOR pathway. miR-93 may serve as a potential therapeutic target in sepsis-induced AKI.

Retraction.

Retraction: "Upregulated microRNA-485 suppresses apoptosis of renal tubular epithelial cells in mice with lupus nephritis via regulating the TGF-β-MAPK signaling pathway by inhibiting RhoA expression," by Yu Tian, Yu-Xiang Han, Hui-Fang Guo, Hong-Tao Jin, Chao Sun, Xuan Qi, Li-Yan Ma, Shi-Wei Bo, J Cell Biochem. 2018; 9154-9167: The above article, published online on 26 August 2018 in Wiley Online Library (https://onlinelibrary.wiley.com/doi/10.1002/jcb.27178) has been retracted by agreement between the journal's Editor in Chief, Prof. Dr. Christian Behl, and Wiley Periodicals LLC. The retraction has been agreed following an investigation based on allegations raised by a third party. A detailed investigation revealed that several image elements of the experimental data were published elsewhere in a different scientific context. Thus, the editors consider the conclusions of this article to be invalid.

Smoking accelerates renal cystic disease and worsens cardiac phenotype in Pkd1-deficient mice

Smoking has been associated with renal disease progression in ADPKD but the underlying deleterious mechanisms and whether it specifically worsens the cardiac phenotype remain unknown. To investigate these matters, Pkd1-deficient cystic mice and noncystic littermates were exposed to smoking from conception to 18 weeks of age and, along with nonexposed controls, were analyzed at 13–18 weeks. Renal cystic index and cyst-lining cell proliferation were higher in cystic mice exposed to smoking than nonexposed cystic animals. Smoking increased serum urea nitrogen in cystic and noncystic mice and independently enhanced tubular cell proliferation and apoptosis. Smoking also increased renal fibrosis, however this effect was much higher in cystic than in noncystic animals. Pkd1 deficiency and smoking showed independent and additive effects on reducing renal levels of glutathione. Systolic function and several cardiac structural parameters were also negatively affected by smoking and the Pkd1-deficient status, following independent and additive patterns. Smoking did not increase, however, cardiac apoptosis or fibrosis in cystic and noncystic mice. Notably, smoking promoted a much higher reduction in body weight in Pkd1-deficient than in noncystic animals. Our findings show that smoking aggravated the renal and cardiac phenotypes of Pkd1-deficient cystic mice, suggesting that similar effects may occur in human ADPKD.

MiR-494-mediated Effects on the NF-κB Signaling Pathway Regulate Lipopolysaccharide-Induced Acute Kidney Injury in Mice

ABSTRACT Objective To explore the effects of miR-494 inhibition through the NF-κB signaling pathway on lipopolysaccharide (LPS)-induced acute kidney injury (AKI) mouse model. Methods The AKI mice induced by LPS were treated with miR-494 antagomir, and the kidney parameters and indicators of oxidative stress were detected. HE and TUNEL staining were performed to observe the kidney histopathology and the apoptosis in renal tubular epithelial cells (RTECs), respectively. The ROS level was measured using dihydroethidium (DHE) staining. In addition, qRT-PCR, western blotting, immunohistochemistry (IHC), and ELISA were also used to detect gene or protein expression. Results LPS-induced AKI mice injected with the miR-494 antagomir showed reduced blood urea nitrogen (BUN) and serum creatinine (Cr) with improved kidney histopathology. The expression levels of p-IKKα/β, p-IκBα and p65 NF-κB in the nucleus were increased in kidney tissues from the LPS-induced AKI mice, and they were decreased by the miR-494 antagomir. Moreover, the results of IHC showed that the miR-494 antagomir downregulated p65 NF-κB in kidney tissues from the LPS-induced AKI mice, accompanied by decreased levels of TNF-α, IL-1β, IL-6, MDA, NO, and ROS but increased levels of SOD and GSH. In addition, the LPS-induced AKI mice had increased apoptosis in RTECs, as well as increased Caspase-3 and Bax and decreased Bcl-2, which were reversed by the miR-494 antagomir. Conclusions The inhibition of miR-494 could reduce inflammatory responses and improve oxidative stress in kidney tissues from LPS-induced AKI mice by blocking the NF-κB pathway accompanying by reduced apoptosis in RTECs.

Effects of andrographolide on renal tubulointersticial injury and fibrosis. Evidence of its mechanism of action

BackgroundDiabetic nephropathy (DN) is associated with renal interstitial injury and fibrosis. Our previous study showed that andrographolide protected against the progression of DN and high glucose (HG)-induced mesangial dysfunction. However, the protective effects of andrographolide on renal tubular epithelial cells have not been fully elucidated. PurposeTo determine the protective effects of andrographolide on renal tubular damage and explore the underlying mechanism. Study designHuman tubular epithelial cells (HK-2 cells) were treated with andrographolide (5 and 10 μM) under HG conditions. Diabetic mice were treated with andrographolide (i.p. 2 and 4 mg/kg, twice per week). MethodsWestern blotting, reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence and flow cytometry were used to analyze the effects of andrographolide on renal tubular injury and fibrotic mechanisms in HK-2 cells. The protective effects of andrographolide against renal tubulointerstitial injury and fibrosis were investigated in diabetic mice fed a high-fat diet (HFD). Renal interstitial tissue was collected at sacrifice for immunohistochemistry, immunofluorescence analysis, RT-PCR and Western blotting to analyze the effects of andrographolide on renal tubular injury and fibrosis. ResultsIn vitro assay results indicated that andrographolide (5 and 10 μM) effectively inhibited HG-induced apoptosis, epithelial-mesenchymal transition (EMT) and collagen deposition in HK-2 cells. Mechanistically, HG stimulated mitochondrial reactive oxygen species (mtROS)-mediated NOD-like receptor family and pyrin domain-containing protein 3 (NLRP3) inflammasome activation and EMT in tubular epithelial cells, and andrographolide (5 and 10 μM) inhibited these effects by ameliorating mitochondrial dysfunction. In vivo, treatment with andrographolide (2 and 4 mg/kg) inhibited renal tubular cell apoptosis, EMT and tubulointerstitial fibrosis, mitochondrial dysfunction and NLRP3 inflammasome activation in diabetic mice. ConclusionAndrographolide (5 and 10 μM) prevents HG-induced renal tubular cell damage, and andrographolide (2 and 4 mg/kg) protects against the progression of diabetic tubular injury and fibrosis in mice by suppressing mitochondrial dysfunction and NLRP3 inflammasome activation.

Dok3 is involved in cisplatin-induced acute kidney injury via regulation of inflammation and apoptosis

Cisplatin-induced acute kidney injury (AKI) is associated with high morbidity and mortality worldwide, but the underlying mechanisms are not fully understood. Downstream-of-kinase 3 (Dok3), a member of the Dok family of adaptor proteins plays a critical role in inflammatory response and immune regulation; however, the role of Dok3 in cisplatin-induced AKI remains unclear. This study explored the effect and potential molecular mechanisms of Dok3 in cisplatin-induced AKI using Dok3 knockout (Dok3−/−) and control mice (129S) with or without administration of a single intraperitoneal injection of cisplatin. Apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, lactate dehydrogenase (LDH) release, and Hoechst staining. Inflammatory factors were measured using ELISA kits. Protein and gene expression levels were measured by western blot analysis and real-time PCR, respectively. The results showed that Dok3 was expressed in renal tubular epithelial cells. Dok3 expression was decreased in kidneys of mice treated with cisplatin and cisplatin-treated HK2 cells. Dok3−/− mice showed lower creatinine levels and NGAL expression, and increased survival rates compared to 129S mice. Cisplatin-induced production of TNF-α and IL-6, and renal tubular cell apoptosis was attenuated in Dok3−/− mice. In vitro experiments demonstrated that HK2 cells overexpressing Dok3 exhibited exacerbated cisplatin-induced apoptosis and production of TNF-α and IL-6. These findings demonstrate that Dok3 regulates cisplatin-induced AKI by regulating apoptosis and inflammation.

MicroRNA 181a-2-3p Alleviates the Apoptosis of Renal Tubular Epithelial Cells via Targeting GJB2 in Sepsis-Induced Acute Kidney Injury.

Acute kidney injury (AKI) is the most common complication of sepsis. MicroRNAs (miRNAs) play important roles in the sepsis-induced AKI. This paper aimed to explore the role of miRNA 181a-2-3p (miR-181a-2-3p) in the sepsis-induced AKI and the underlying mechanism. Our results revealed that miR-181a-2-3p showed low expression levels in patients with sepsis and mouse models undergoing cecal ligation and puncture (CLP). The addition of miR-181a-2-3p antagonists aggravated the sepsis-induced kidney injuries and inflammatory response in CLP mouse models, as suggested by hematoxylin and eosin (H&E) staining and quantitative real-time PCR (qRT-PCR). In addition, miR-181a-2-3p mimic alleviated the lipopolysaccharide (LPS)-induced inflammatory response, along with apoptosis of TCMK-1. Moreover, results from the GSE46955 data set indicated that GJB2 was highly expressed in septic patients but lowly expressed after recovery. Further, the dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were carried out, which confirmed that GJB2 was a target of miR-181a-2-3p, and overexpression of GJB2 reversed the anti-inflammatory and antiapoptotic effects of miR-181a-2-3p mimic on the LPS-induced sepsis cell models. In conclusion, miR-181a-2-3p alleviates the inflammatory response and cell apoptosis of septic patients and animal models by upregulating GJB2 expression, which may provide a new therapeutic strategy for sepsis.

Protective effect and mechanism of Baicalin on acute kidney injury in septic mice

To observe the protective effect and mechanism of different doses of Baicalin (BAI) on acute kidney injury (AKI) in septic mice. According to the random number table, 100 mice were divided into sham operation group (Sham group), cecal ligation and perforation (CLP) induced sepsis model group (CLP group) and BAI pretreatment groups. The mice in BAI pretreatment groups were divided into low-, medium- and high-dose groups (BAI-L+CLP, BAI-M+CLP, BAI-H+CLP groups), with 20 mice in each group. A murine sepsis associated-acute kidney injury (SA-AKI) model was reproduced using CLP. The mice in the Sham group were only opened and closed the abdomen, without ligating or perforating the cecum. The mice in the BAI pretreatment groups were given BAI 25, 50 and 100 mg/kg daily for 3 days, and CLP was performed at 6 hours after administration of BAI at the 3rd day to reproduce sepsis model. The mice in the Sham group and CLP group were given the same amount of distilled water as control. Ten mice were sacrificed at 24 hours after operation to collect orbital blood for renal function determination [serum creatinine (SCr), blood urea nitrogen (BUN), plasma neutrophil gelatinase-associated lipocalin (pNGAL) and plasma kidney injury molecule-1 (pKIM-1)] by enzyme linked immunosorbent assay (ELISA). The kidney tissue was collected to observe the kidney tissue injury under light microscope after hematoxylin-eosin (HE) staining. The TdT-mediated dUTP nick-end labeling (TUNEL) was used to detect the apoptosis of renal tubular epithelial cells. Western blotting was used to detect the expression of cell FLICE like inhibitory protein (c-FLIP) in renal tissue. The remaining 10 mice in each group were used to calculate the survival rate of 7 days after operation. The renal tubular epithelial cells in the CLP group were massively degenerated with necrosis, the renal tubular lumen was significantly expanded, and inflammatory cells were widely infiltrated in the renal interstitium. Furthermore, the renal function deteriorated rapidly. Compared with the CLP group, the renal function of mice pretreated with low dose of BAI was improved, but the difference was not significant. Compared with the CLP group, the renal function in the mice pretreated with medium and high doses of BAI was significantly improved, the SCr, BUN, pNGAL and pKIM-1 were significantly reduced [SCr (μmol/L): 135.16±5.18, 125.70±5.26 vs. 170.42±5.42; BUN (mmol/L): 33.59±1.77, 27.29±1.61 vs. 45.68±1.39; pNGAL (μg/L): 91.29±4.68, 73.40±3.77 vs. 131.50±6.55; pKIM-1 (μg/L): 6.34±0.30, 5.51±0.35 vs. 8.03±0.29; all P < 0.01], the pathological injury of renal tissue was significantly decreased, the apoptotic number of renal tubular epithelial cells was significantly reduced (cells/HP: 16.20±0.49, 13.10±0.66 vs. 29.60±0.49, both P < 0.01), and the expression of c-FLIP protein in renal tissue was significantly increased [c-FLIP protein (c-FLIP/GAPDH): 0.35±0.02, 0.46±0.02 vs. 0.21±0.01, both P < 0.01]. No mouse in the Sham group died within 7 days. Compared with the CLP group, the average survival time of the mice within 7 days in the BAI-L+CLP, BAI-M+CLP and BAI-H+CLP groups was significantly prolonged with a dose-dependent manner (days: 3.5±2.5, 5.4±2.2, 5.9±1.9 vs. 2.1±1.2; Log-Rank test: χ2 = 73.410, P < 0.001). Pretreatment with medium and high doses of BAI can significantly improve the renal function in mice with SA-AKI, decrease the pathological damage and increase the survival of mice, and its mechanism may be related to promoting the increase of c-FLIP protein expression and inhibiting cell apoptosis.

Network-Based Expression Analyses and Experimental Verifications Reveal the Involvement of STUB1 in Acute Kidney Injury.

Acute kidney injury (AKI) is a severe and frequently observed condition associated with high morbidity and mortality. The molecular mechanisms underlying AKI have not been elucidated due to the complexity of the pathophysiological processes. Thus, we investigated the key biological molecules contributing to AKI based on the transcriptome profile. We analyzed the RNA sequencing data from 39 native human renal biopsy samples and 9 reference nephrectomies from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) and Gene Ontology (GO) analysis revealed that various GO terms were dysregulated in AKI. Gene set enrichment analysis (GSEA) highlighted dysregulated pathways, including “DNA replication,” “chemokine signaling pathway,” and “metabolic pathways.” Furthermore, the protein-to-protein interaction (PPI) networks of the DEGs were constructed, and the hub genes were identified using Cytoscape. Moreover, weighted gene co-expression network analysis (WGCNA) was performed to validate the DEGs in AKI-related modules. Subsequently, the upregulated hub genes STUB1, SOCS1, and VHL were validated as upregulated in human AKI and a mouse cisplatin-induced AKI model. Moreover, the biological functions of STUB1 were investigated in renal tubular epithelial cells. Cisplatin treatment increased STUB1 expression in a dose-dependent manner at both the mRNA and protein levels. Knockdown of STUB1 by siRNA increased the expression of proapoptotic Bax and cleaved caspase-3 while decreasing antiapoptotic Bcl-2. In addition, silencing STUB1 increased the apoptosis of HK-2 cells and the proinflammatory cytokine production of IL6, TNFα, and IL1β induced by cisplatin. These results indicated that STUB1 may contribute to the initiation and progression of AKI by inducing renal tubular epithelial cell apoptosis and renal inflammation.

Circulating Mitochondrial DNA Stimulates Innate Immune Signaling Pathways to Mediate Acute Kidney Injury.

Mitochondrial dysfunction is increasingly considered as a critical contributor to the occurrence and progression of acute kidney injury (AKI). However, the mechanisms by which damaged mitochondria mediate AKI progression are multifactorial and complicated. Mitochondrial DNA (mtDNA) released from damaged mitochondria could serve as a danger-associated molecular pattern (DAMP) and activate the innate immune system through STING, TLR9, NLRP3, and some other adaptors, and further mediate tubular cell inflammation and apoptosis. Accumulating evidence has demonstrated the important role of circulating mtDNA and its related pathways in the progression of AKI, and regulating the proteins involved in these pathways may be an effective strategy to reduce renal tubular injury and alleviate AKI. Here, we aim to provide a comprehensive overview of recent studies on mtDNA-mediated renal pathological events to provide new insights in the setting of AKI.

Ochratoxin A induces human kidney tubular epithelial cell apoptosis through regulating lipid raft/PTEN/AKT signaling pathway.

Ochratoxin A (OTA) is a fungal toxin that causes serious threat to human health. OTA could lead to the injury of various tissues, especially kidney injury. However, the toxic effects of OTA on human kidney tubular epithelial cell (HK-2) and the possible mechanism remains poorly understood. This study was to investigate the toxic effects of OTA on HK-2 and elucidate the molecular mechanism. HK-2 cells were treated OTA to evaluate the effect of OTA on cell viability and apoptosis. OTA inhibited the growth of HK-2 in a concentration-dependent manner. With the concentration increased, OTA significantly lead to the apoptosis of HK-2. OTA could increase the levels of reactive oxygen species (ROS) and Malondialdehyde (MDA). Superoxide dismutase (SOD) and glutathione (GSH) activities were decreased by OTA. Furthermore, OTA increased Caspase-3 and Bax expression and decreased BCL2 expression. Compared to the control group, the expression of PTEN was increased and the expression of PI3K and AKT were decreased in OTA treated groups. In addition, we found OTA could disrupt the formation of lipid raft by attenuating sphingomyelin and cholesterol levels. In conclusion, our results indicated that OTA induces apoptosis in HK-2 through regulating PTEN/AKT signaling pathway via disrupting lipid raft formation.

C-X3-C motif chemokine ligand 1/receptor 1 regulates the M1 polarization and chemotaxis of macrophages after hypoxia/reoxygenation injury

BackgroundMacrophages play an important role in renal ischemia reperfusion injury, but the functional changes of macrophages under hypoxia/reoxygenation and the related mechanism are unclear and need to be further clarified. MethodsThe effects of hypoxia/reoxygenation on functional characteristics of RAW264.7 macrophages were analyzed through the protein expression detection of pro-inflammatory factors TNF-α and CD80, anti-inflammatory factors ARG-1 and CD206. The functional implications of C-X3-C motif chemokine receptor 1(CX3CR1) down-regulation in hypoxic macrophages were explored using small interfering RNA technology. Significance was assessed by the parametric t-test or nonparametric Mann–Whitney test for two group comparisons, and a one-way ANOVA or the Kruskal–Wallis test for multiple group comparisons. ResultsHypoxia/reoxygenation significantly increased the protein expression of M1-related pro-inflammatory factors TNF-α, CD80 and chemokine C-X3-C motif chemokine ligand 1 (CX3CL1)/CX3CR1 and inhibited the protein expression of M2-related anti-inflammatory factors ARG-1 and CD206 in a time-dependent manner in RAW264.7 cells. However, the silencing of CX3CR1 in RAW264.7 cells using specific CX3CR1-siRNA, significantly attenuated the increase in protein expression of TNF-α (P < 0.05) and CD80 (P < 0.01) and the inhibition of ARG-1 (P < 0.01) and CD206 (P < 0.01) induced by hypoxia/reoxygenation. In addition, we also found that hypoxia/reoxygenation could significantly enhance the migration (2.2-fold, P < 0.01) and adhesion capacity (1.5-fold, P < 0.01) of RAW264.7 macrophages compared with the control group, and CX3CR1-siRNA had an inhibitory role (40% and 20% reduction, respectively). For elucidating the mechanism, we showed that the phosphorylation levels of ERK (P < 0.01) and the p65 subunit of NF-κB (P < 0.01) of the RAW264.7 cells in the hypoxic/reoxygenation group were significantly increased, which could be attenuated by down-regulation of CX3CR1 expression (P < 0.01, both). ERK inhibitors also significantly blocked the effects of hypoxic/reoxygenation on the protein expression of M1-related pro-inflammatory factors TNF-α, CD80 and M2-related anti-inflammatory factors ARG-1 and CD206. Moreover, we found that conditioned medium from polarized M1 macrophages induced by hypoxia/reoxygenation, notably increased the degree of apoptosis of hypoxia/reoxygenation-induced TCMK-1 cells, and promoted the protein expression of pro-apoptotic proteins bax (P < 0.01) and cleaved-caspase 3 (P < 0.01) and inhibited the expression of anti-apoptotic protein bcl-2 (P < 0.01), but silencing CX3CR1 in macrophages had a protective role. Finally, we also found that the secretion of soluble CX3CL1 in RAW264.7 macrophages under hypoxia/reoxygenation was significantly increased. ConclusionsThe findings suggest that hypoxia/reoxygenation could promote M1 polarization, cell migration, and adhesion of macrophages, and that polarized macrophages induce further apoptosis of hypoxic renal tubular epithelial cells by regulating of CX3CL1/CX3CR1 signaling pathway.

LncRNA TUG1 ameliorates diabetic nephropathy via inhibition of PU.1/RTN1 signaling pathway.

Diabetic nephropathy (DN) is a leading cause of end-stage renal failure. The study aimed to investigate whether long noncoding RNA taurine-upregulated gene 1 (TUG1) can ameliorate the endoplasmic reticulum stress (ERS) and apoptosis of renal tubular epithelial cells in DN, and the underlying mechanism. The DN mouse model was established by streptozocin injection, and the human renal tubular epithelial cell line HK-2 was treated with high glucose (HG) to mimic DN in vitro. The molecular mechanism was explored through dual-luciferase activity assay, RNA pull-down assay, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (CHIP) assay. The expression of TUG1 was significantly decreased in the renal tubules of DN model mice. Overexpression of TUG1 reduced the levels of ERS markers and apoptosis markers by inhibiting reticulon-1 (RTN1) expression in HG-induced HK-2 cells. Furthermore, TUG1 down-regulated RTN1 expression by inhibiting the binding of transcription factor PU.1 to the RTN1 promoter, thereby reducing the levels of ERS markers and apoptosis markers. Meanwhile, TUG1-overexpression adenovirus plasmids injection significantly alleviated tubular lesions, and reduced RTN1 expression, ERS markers and apoptosis markers, whereas these results were reversed by injection of PU.1-overexpression adenovirus plasmids. TUG1 restrains the ERS and apoptosis of renal tubular epithelial cells and ameliorates DN through inhibition of transcription factor PU.1.

Protective Effect of Panduratin A on Cisplatin-Induced Apoptosis of Human Renal Proximal Tubular Cells and Acute Kidney Injury in Mice.

Cisplatin is an effective chemotherapy but its main side effect, acute kidney injury, limits its use. Panduratin A, a bioactive compound extracted from Boesenbergia rotunda, shows several biological activities such as anti-oxidative effects. The present study investigated the nephroprotective effect of panduratin A on cisplatin-induced renal injury. We investigated the effect of panduratin A on the toxicity of cisplatin in both mice and human renal cell cultures using RPTEC/TERT1 cells. The results demonstrated that panduratin A ameliorates cisplatin-induced renal toxicity in both mice and RPTEC/TERT1 cells by reducing apoptosis. Mice treated with a single intraperitoneal (i.p.) injection of cisplatin (20 mg/kg body weight (BW)) exhibited renal tubule injury and impaired kidney function as shown by histological examination and increased serum creatinine. Co-administration of panduratin A (50 mg/kg BW) orally improved kidney function and ameliorated renal tubule injury of cisplatin by inhibiting activation of extracellular signal-regulated kinase (ERK)1/2 and caspase 3. In human renal proximal tubular cells, cisplatin induced cell apoptosis by activating pro-apoptotic proteins (ERK1/2 and caspase 3), and reducing the anti-apoptotic protein (Bcl-2). These effects were significantly ameliorated by co-treatment with panduratin A. Interestingly, panduratin A did not alter intracellular accumulation of cisplatin. It did not alter the anti-cancer efficacy of cisplatin in either human colon or non-small cell lung cancer cell lines. The present study highlights panduratin A has a potential protective effect on cisplatin's nephrotoxicity.

Retraction Note to: Silibinin ameliorates arsenic induced nephrotoxicity by abrogation of oxidative stress, inflammation and apoptosis in rats

Arsenic (As) is an environmental and industrial pollutant that affects various organs in human and experimental animals. Silibinin is a naturally occurring plant bioflavonoid found in the milk thistle of Silybum marianum, which has been reported to have a wide range of pharmacological properties. A body of evidence has accumulated implicating the free radical generation with subsequent oxidative stress in the biochemical and molecular mechanisms of As toxicity. Since kidney is the critical target organ of chronic As toxicity, we carried out this study to investigate the effects of silibinin on As-induced toxicity in the kidney of rats. In experimental rats, oral administration of sodium arsenite [NaAsO2, 5 mg/(kg day)] for 4 weeks significantly induced renal damage which was evident from the increased levels of serum urea, uric acid, creatinine with a significant (p < 0.05) decrease in creatinine clearance. As also significantly decreased the levels of urea, uric acid and creatinine in urine. A markedly increased levels of lipid peroxidation markers (thiobarbituric acid reactive substances and lipid hydroperoxides) and protein carbonyl contents with significant (p < 0.05) decrease in non-enzymatic antioxidants (total sulfhydryl groups, reduced glutathione, vitamin C and vitamin E) and enzymatic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glutathione S-transferase), Glutathione metabolizing enzymes (glutathione reductase and glutathione-6-phosphate dehydrogenase) and membrane bound ATPases were also observed in As treated rats. Co-administration of silibinin (75 mg/kg day) along with As resulted in a reversal of As-induced biochemical changes in kidney accompanied by a significant decrease in lipid peroxidation and an increase in the level of renal antioxidant defense system. The histopathological and immunohistochemical studies in the kidney of rats also shows that silibinin (75 mg/kg day) markedly reduced the toxicity of As and preserved the normal histological architecture of the renal tissue, inhibited the caspase-3 mediated tubular cell apoptosis and decreased the NADPH oxidase, iNOS and NF-κB over expression by As and upregulated the Nrf2 expression in the renal tissue. The present study suggests that the nephroprotective potential of silibinin in As toxicity might be due to its antioxidant and metal chelating properties, which could be useful for achieving optimum effects in As-induced renal damage.

Hyperhomocysteinemia exacerbates ischemia-reperfusion injury-induced acute kidney injury by mediating oxidative stress, DNA damage, JNK pathway, and apoptosis.

BackgroundHyperhomocysteinemia (HHcy) plays an important role in the progression of many kidney diseases; however, the relationship between HHcy and ischemia-reperfusion injury (IRI)-induced acute kidney injury (IRI-induced AKI) is far from clear. In this study, we try to investigate the effect and possible mechanisms of HHcy on IRI-induced AKI.MethodsTwenty C57/BL6 mice were reared with a regular diet or high methionine diet for 2 weeks (to generate HHcy mice); after that, mice were subgrouped to receive sham operation or ischemia-reperfusion surgery. Twenty four hour after reperfusion, serum creatinine, blood urea nitrogen, and Malondialdehyde (MDA) were measured. H&E staining for tubular injury, western blot for γH2AX, JNK, p-JNK, and cleaved caspase 3, and TUNEL assay for tubular cell apoptosis were also performed.ResultsOur results showed that HHcy did not influence the renal function and histological structure, as well as the levels of MDA, γH2AX, JNK, p-JNK, and tubular cell apoptosis in control mice. However, in IRI-induced AKI mice, HHcy caused severer renal dysfunction and tubular injury, higher levels of oxidative stress, DNA damage, JNK pathway activation, and tubular cell apoptosis.ConclusionOur results demonstrated that HHcy could exacerbate IRI-induced AKI, which may be achieved through promoting oxidative stress, DNA damage, JNK pathway activation, and consequent apoptosis.

Recombinant Long-Acting Thioredoxin Ameliorates AKI to CKD Transition via Modulating Renal Oxidative Stress and Inflammation.

An effective strategy is highly desirable for preventing acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Thioredoxin-1 (Trx), a redox-active protein that has anti-oxidative and anti-inflammatory properties, would be a candidate for this but its short half-life limits its clinical application. In this study, we examined the renoprotective effect of long-acting Trx that is comprised of human albumin and Trx (HSA-Trx) against AKI to CKD transition. AKI to CKD mice were created by renal ischemia-reperfusion (IR). From day 1 to day 14 after renal IR, the recovery of renal function was accelerated by HSA-Trx administration. On day 14, HSA-Trx reduced renal fibrosis compared with PBS treatment. At the early phase of fibrogenesis (day 7), HSA-Trx treatment suppressed renal oxidative stress, pro-inflammatory cytokine production and macrophage infiltration, thus ameliorating tubular injury and fibrosis. In addition, HSA-Trx treatment inhibited G2/M cell cycle arrest and apoptosis in renal tubular cells. While renal Trx protein levels were decreased after renal IR, the levels were recovered by HSA-Trx treatment. Together, HSA-Trx has potential for use in the treatment of AKI to CKD transition via its effects of modulating oxidative stress and inflammation.

Dissecting the Involvement of Ras GTPases in Kidney Fibrosis.

Many different regulatory mechanisms of renal fibrosis are known to date, and those related to transforming growth factor-β1 (TGF-β1)-induced signaling have been studied in greater depth. However, in recent years, other signaling pathways have been identified, which contribute to the regulation of these pathological processes. Several studies by our team and others have revealed the involvement of small Ras GTPases in the regulation of the cellular processes that occur in renal fibrosis, such as the activation and proliferation of myofibroblasts or the accumulation of extracellular matrix (ECM) proteins. Intracellular signaling mediated by TGF-β1 and Ras GTPases are closely related, and this interaction also occurs during the development of renal fibrosis. In this review, we update the available in vitro and in vivo knowledge on the role of Ras and its main effectors, such as Erk and Akt, in the cellular mechanisms that occur during the regulation of kidney fibrosis (ECM synthesis, accumulation and activation of myofibroblasts, apoptosis and survival of tubular epithelial cells), as well as the therapeutic strategies for targeting the Ras pathway to intervene on the development of renal fibrosis.

PARK7 Protects Against Chronic Kidney Injury and Renal Fibrosis by Inducing SOD2 to Reduce Oxidative Stress.

Renal fibrosis is the final common pathway to chronic kidney diseases regardless of etiology. Parkinson disease protein 7 (PARK7) is a multifunctional protein involved in various cellular processes, but its pathophysiological role in kidneys remain largely unknown. Here, we have determined the role of PARK7 in renal fibrosis and have further elucidated the underlying mechanisms by using the in vivo mouse model of unilateral ureteric obstruction (UUO) and the in vitro model of transforming growth factor-b (TGFB1) treatment of cultured kidney proximal tubular cells. PARK7 decreased markedly in atrophic kidney tubules in UUO mice, and Park7 deficiency aggravated UUO-induced renal fibrosis, tubular cell apoptosis, ROS production and inflammation. In vitro, TGFB1 treatment induced fibrotic changes in renal tubular cells, which was accompanied by alterations of PARK7. Park7 knockdown exacerbated TGFB1-induced fibrotic changes, cell apoptosis and ROS production, whereas Park7 overexpression or treatment with ND-13 (a PARK7-derived peptide) attenuated these TGFB1-induced changes. Mechanistically, PARK7 translocated into the nucleus of renal tubular cells following TGFB1 treatment or UUO, where it induced the expression of SOD2, an antioxidant enzyme. Taken together, these results indicate that PARK7 protects against chronic kidney injury and renal fibrosis by inducing SOD2 to reduce oxidative stress in tubular cells.