Methionine Sulfoxide Reductase A Deficiency Exacerbates Cisplatin-Induced Nephrotoxicity via Increased Mitochondrial Damage and Renal Cell Death

Ochratoxin A induces hepatic and renal toxicity in mice through increased oxidative stress, mitochondrial damage, and multiple cell death mechanisms

Ochratoxin A (OTA) is a widespread food toxin produced by Aspergillus ochraceus and other molds. In this study, we developed and established acute OTA toxicity conditions in mice, which received daily oral doses of OTA between 0.5 up to 8 mg/kg body weight up to 7 days and were subjected to histological and biochemical analysis to characterize renal and hepatic damage. Oral administration of OTA for 7 days resulted in loss of body weight in a dose-dependent manner and increased the levels of serum biomarkers of hepatic and renal damage. The kidney was more sensitive to OTA-induced damage than the liver. In addition to necrosis, OTA induced hepatic and renal apoptosis in dose- and time-dependent manners. Especially, a high dose of OTA (8 mg/kg body weight) administered for 7 days led to necroptosis in both liver and kidney tissues. OTA dose-dependently increased the oxidative stress levels, including lipid peroxidation, in the liver and kidneys. OTA disrupted mitochondrial dynamics and structure in hepatic and renal cells, leading to the dysregulation of mitochondrial homeostasis. OTA increased transferrin receptor 1 and decreased glutathione peroxidase 4 levels in a dose- and time-dependent manner. These results suggest the induction of ferroptosis. Collectively, this study highlighted the characteristics of acute OTA-induced hepatic and renal toxicity in mice in terms of oxidative stress, mitochondrial damage, and multiple cell death mechanisms, including necroptosis and ferroptosis.

Vitamin E-Inhibited Phoxim-Induced Renal Oxidative Stress and Mitochondrial Apoptosis In Vivo and In Vitro of Piglets

Exposure to phoxim at low levels caused bioaccumulation with neurotoxicity but also induced oxidative stress, tissue damage, and abnormal nutrient metabolism. This study described that vitamin E ameliorates phoxim-induced nephrotoxicity via inhibiting mitochondrial apoptosis. In vivo, 24 healthy piglets were treated with phoxim (0 mg/kg and 500 mg/kg) and vitamin E + phoxim (vitamin E + phoxim: 200 mg/kg + 500 mg/kg). In vitro, PK15 cells were treated with phoxim (0 mg/L and 1 mg/L) and vitamin E + phoxim (phoxim + vitamin E: 1 mg/L + 1 mg/L) for 12 h and 24 h. Our results indicated that accumulation of ROS, oxidative stress, and renal cell injury through stimulation of mitochondrial apoptosis resulted in phoxim-induced nephrotoxicity. Phoxim resulted in swollen mitochondria, blurred internal cristae, renal glomerular atrophy, and renal interstitial fibrosis. Vitamin E alleviated the adverse effects of phoxim by reducing ROS and improving antioxidant capacity in vivo and in vitro. Vitamin E significantly increased SDH in vitro (p < 0.01), while it decreased ROS, Bad, and cyto-c in vitro and SOD and CAT in vivo (p < 0.05). Vitamin E ameliorated phoxim-induced renal histopathologic changes, and mitochondria swelled. In addition, vitamin E regulates phoxim-induced apoptosis by alleviating oxidative damage to the mitochondria.

Epoxyeicosatrienoic acid administration or soluble epoxide hydrolase inhibition attenuates renal fibrogenesis in obstructive nephropathy

Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites with biological effects, including antiapoptotic, anti-inflammatory, and antifibrotic functions. Soluble epoxide hydrolase (sEH)-mediated hydrolysis of EETs to dihydroxyeicosatrienoic acids (DHETs) attenuates these effects. Recent studies have demonstrated that inhibition of sEH prevents renal tubulointerstitial fibrosis and inflammation in the chronic kidney disease model. Given the pathophysiological role of the EET pathway in chronic kidney disease, we investigated if administration of EET regioisomers and/or sEH inhibition will promote antifibrotic and renoprotective effects in renal fibrosis following unilateral ureteral obstruction (UUO). EETs administration abolished tubulointerstitial fibrogenesis, as demonstrated by reduced fibroblast activation and collagen deposition after UUO. The inflammatory response was prevented as demonstrated by decreased neutrophil and macrophage infiltration and expression of cytokines in EET-administered UUO kidneys. EET administration and/or sEH inhibition significantly reduced M1 macrophage markers, whereas M2 macrophage markers were highly upregulated. Furthermore, UUO-induced oxidative stress, tubular injury, and apoptosis were all downregulated following EET administration. Combined EET administration and sEH inhibition, however, had no additive effect in attenuating inflammation and renal interstitial fibrogenesis after UUO. Taken together, our findings provide a mechanistic understanding of how EETs prevent kidney fibrogenesis during obstructive nephropathy and suggest EET treatment as a potential therapeutic strategy to treat fibrotic diseases.NEW & NOTEWORTHY Epoxyeicosatrienoic acids (EETs) are cytochrome P-450-dependent antihypertensive and anti-inflammatory derivatives of arachidonic acid, which are highly abundant in the kidney and considered renoprotective. We found that EET administration and/or soluble epoxide hydrolase inhibition significantly attenuates oxidative stress, renal cell death, inflammation, macrophage differentiation, and fibrogenesis following unilateral ureteral obstruction. Our findings provide a mechanistic understanding of how EETs prevent kidney fibrogenesis during obstructive nephropathy and suggest that EET treatment may be a potential therapeutic strategy to treat fibrotic diseases.

The selenoprotein methionine sulfoxide reductase B1 (MSRB1)

Methionine (Met) can be oxidized to methionine sulfoxide (MetO), which exist as R- and S-diastereomers. Present in all three domains of life, methionine sulfoxide reductases (MSR) are the enzymes that reduce MetO back to Met. Most characterized among them are MSRA and MSRB, which are strictly stereospecific for the S- and R-diastereomers of MetO, respectively. While the majority of MSRs use a catalytic Cys to reduce their substrates, some employ selenocysteine. This is the case of mammalian MSRB1, which was initially discovered as selenoprotein SELR or SELX and later was found to exhibit an MSRB activity. Genomic analyses demonstrated its occurrence in most animal lineages, and biochemical and structural analyses uncovered its catalytic mechanism. The use of transgenic mice and mammalian cell culture revealed its physiological importance in the protection against oxidative stress, maintenance of neuronal cells, cognition, cancer cell proliferation, and the immune response. Coincident with the discovery of Met oxidizing MICAL enzymes, recent findings of MSRB1 regulating the innate immunity response through reversible stereospecific Met-R-oxidation of cytoskeletal actin opened up new avenues for biological importance of MSRB1 and its role in disease. In this review, we discuss the current state of research on MSRB1, compare it with other animal Msrs, and offer a perspective on further understanding of biological functions of this selenoprotein.

Short-term control of diet affects cisplatin-induced acute kidney injury through modulation of mitochondrial dynamics and mitochondrial GSH

Obesity affects acute kidney injury (AKI) induced by various clinical settings, including transplantation and cisplatin-cancer therapy. However, the effect of short-term food intake change remains to be defined. Here, we investigated the effects of short-term high-fat diet intake and food restriction on cisplatin-induced AKI. Mice were fed either a high-fat diet (HFD) or a low-fat diet (LFD) for 11 days or were not fed for 40 hh (fasting), before cisplatin administration. Cisplatin-induced functional and structural damages to kidneys in both HFD- and LFD-fed mice, with greater damages in HFD-fed mice than LFD-fed mice. HFD decreased mitochondrial total glutathione (tGSH) level, along with increases in the plasma and kidney cholesterol levels. Cisplatin caused the increase of kidney cholesterol levels and oxidative stress, along with the decrease of mitochondrial tGSH levels. In addition, cisplatin-induced mitochondrial damage and apoptosis of tubular cells in both HFD- and LFD-fed mice. An increase of Fis1 (mitochondria fission 1 protein), whereas a decrease of Opa1 (mitochondria fusion 1 protein) occurred by cisplatin. These cisplatin effects were greater in HFD-fed mice than in LFD-fed mice. Administration of mitochondria-specific antioxidant treatment during HFD feeding inhibited these cisplatin-induced changes. Fasting for 40 h also significantly reduced the cisplatin-induced changes mentioned above. These data demonstrate that short-term HFD intake worsens cisplatin-induced oxidative stress by the reduction of mitochondrial tGSH, resulting in increased cisplatin-induced nephrotoxicity. These data newly indicate that the control of calorie intake, even for a short period, affects kidney susceptibility to injury. Although most studies described the effects of a long-term high-fat diet on the kidneys, in this study, we found that even if a high-fat diet was consumed for a short-term, physiological changes and mitochondria tGSH decrease in the kidneys, and consequently increased cisplatin-nephrotoxic susceptibility. These data suggest the association of calorie intake with kidney susceptibility to cisplatin.

Honokiol ameliorates cisplatin-induced acute kidney injury via inhibition of mitochondrial fission

BACKGROUND AND PURPOSE

Mitochondrial damage and oxidative stress are the crucial contributors to the tubular cell injury and death in acute kidney injury (AKI). Novel therapeutic strategies targeting mitochondria protection and halting the progression of AKI are urgently needed. Honokiol (HKL) is a small-molecule polyphenol that exhibits extraordinary cytoprotective effects, such as anti-inflammatory and anti-oxidative properties. Thus, we wonder whether HKL could ameliorate cisplatin-induced AKI via preventing mitochondrial dysfunction.

EXPERIMENTAL APPROACH

AKI was induced by cisplatin administration. Biochemical and histological analysis were applied to determine kidney injury. The effect of HKL on mitochondrial function and morphology were evaluated by immunohistochemistry, transmission electron microscopy, immunoblot and immunofluorescence. To investigate the mechanism of HKL in mitochondrial dynamics remodeling and resistance to apoptosis, we did transfection experiments, immunoblot, immunoprecipitation and flow cytometry assay.

KEY RESULTS

We demonstrated that the prominent mitochondrial fragmentation occurred in experimental models of cisplatin-induced nephrotoxicity, which was coupled with radical oxygen species (ROS) overproduction, deterioration of mitochondrial function, release of apoptogenic factors, and consequent apoptosis. HKL treatment exhibited notable renoprotection and attenuated these perturbations. Mechanically, we show that HKL treatment recovered the expression of SIRT3 and improved AMPK activity in tubular cells exposure to cisplatin, which preserved the Drp1 phosphorylation at Ser637 and blocked its translocation to mitochondria, consequently preventing mitochondrial fragmentation and subsequent cell injury and death.

CONCLUSIONS AND IMPLICATIONS

Our results indicate that HKL may protect against cisplatin-induced AKI by preserving mitochondrial integrity and fitness through a mechanism of SIRT3/AMPK-dependent mitochondrial dynamics remodeling.

Cisplatin induces lung cell cilia disruption and lung damage via oxidative stress

BACKGROUND

Cisplatin (cis-diamminedichloroplatinum II) is widely used for the treatment of cancer, but its cellular toxicity, especially in the form of oxidative stress, limits its use in multiple organs including the lungs. As a cellular organelle, cilia play an important role in cellular function and can be damaged by oxidative stress. However, the effect of cisplatin-induced lung toxicity on cilia has not yet been defined. Herein, we investigated the association of cilia and oxidative stress with cisplatin-induced lung damage.

METHODS

Mice were administered with cisplatin. Some mice were treated with 2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride (Mito-TEMPO, a mitochondria-specific antioxidant) before the administration of cisplatin. Disruption of cilia was evaluated by the detection of ciliary proteins and fragments in the bronchoalveolar lavage fluid (BALF).

RESULTS

Cisplatin caused the thickening of interalveolar septa, infiltration of immune cells into the interalveolar septa, and increased protein concentration and total cell number in the BALF. Cisplatin also increased ciliary fragments and proteins in the BALF. In the lungs, cisplatin increased the production of hydrogen peroxide, lipid peroxidation, and apoptosis, while decreasing manganese superoxide dismutase, isocitrate dehydrogenase 2, and catalase expression. Treatment with Mito-TEMPO prevented cisplatin-induced lung damage, ciliary fragmentation, oxidative stress, and apoptosis.

CONCLUSION

By increasing oxidative stress in the lung, cisplatin induces lung cell damage, disruption of cilia, and release of disrupted cilia into the BALF. This suggests that cisplatin-induced lung damage can damage the cilia, manifesting as increased ciliary proteins in the BALF.

Mitochondrial Dysfunction in Cardiorenal Syndrome 3: Renocardiac Effect of Vitamin C

Cardiorenal syndrome (CRS) is a pathological link between the kidneys and heart, in which an insult in a kidney or heart leads the other organ to incur damage. CRS is classified into five subtypes, and type 3 (CRS3) is characterized by acute kidney injury as a precursor to subsequent cardiovascular changes. Mitochondrial dysfunction and oxidative and nitrosative stress have been reported in the pathophysiology of CRS3. It is known that vitamin C, an antioxidant, has proven protective capacity for cardiac, renal, and vascular endothelial tissues. Therefore, the present study aimed to assess whether vitamin C provides protection to heart and the kidneys in an in vivo CRS3 model. The unilateral renal ischemia and reperfusion (IR) protocol was performed for 60 min in the left kidney of adult mice, with and without vitamin C treatment, immediately after IR or 15 days after IR. Kidneys and hearts were subsequently collected, and the following analyses were conducted: renal morphometric evaluation, serum urea and creatinine levels, high-resolution respirometry, amperometry technique for NO measurement, gene expression of mitochondrial dynamic markers, and NOS. The analyses showed that the left kidney weight was reduced, urea and creatinine levels were increased, mitochondrial oxygen consumption was reduced, NO levels were elevated, and Mfn2 expression was reduced after 15 days of IR compared to the sham group. Oxygen consumption and NO levels in the heart were also reduced. The treatment with vitamin C preserved the left kidney weight, restored renal function, reduced NO levels, decreased iNOS expression, elevated constitutive NOS isoforms, and improved oxygen consumption. In the heart, oxygen consumption and NO levels were improved after vitamin C treatment, whereas the three NOS isoforms were overexpressed. These data indicate that vitamin C provides protection to the kidneys and some beneficial effects to the heart after IR, indicating it may be a preventive approach against cardiorenal insults.

Effects of Long-Term Exposure to Copper on the Keap1/Nrf2 Signaling Pathway and Msr-Related Redox Status in the Kidneys of Rats

The objective of the present study was to examine the effects of long-term exposure on oxidative damage, Keap1/Nrf2 signaling pathway, and Msr-related redox status in the kidneys of rats. Therefore, in this experimental study, a total of 32 CD-1 rats were randomized into 4 groups and treated with 30-, 60-, and 120-mg/kg Cu for 24 weeks. Different serum biomarkers suggestive of renal functions, pathological changes, and oxidative stress were analyzed in kidney tissues. Moreover, the levels of the Keap1/Nrf2 signaling pathway and redox status-related gene mRNA and proteins were also detected. The results indicated that Cu exposure dramatically increased the contents of creatinine and carbamide. Furthermore, histopathological alterations and mitochondrial damage in kidneys of rats of different Cu-treated groups were obviously observed. In addition, Cu exposure markedly changed the levels of glutathione, catalase, and total antioxidant capacity, and upregulated the contents of protein carbonyl, nitric oxide, and malondialdehyde. Moreover, higher levels of Cu treatments significantly increased the expression of Keap1/Nrf2 signaling pathway and redox status-related genes (NQO1, SOD-1, TRX, MsrA, MsrB1, MsrB2, MsrB3). Simultaneously, the mRNA expression levels of Nrf2, HO-1, and CAT were upregulated in rats exposed to 30- and 60-mg/kg Cu, but downregulated in the 120-mg/kg Cu group compared with the control group. Moreover, the Keap1/Nrf2 signaling pathway and redox status-related protein expression levels (HO-1, SOD-1, TRX, MsrA, MsrB1, MsrB2) were significantly increased in treated rats. In summary, it is suggested that the Keap1/Nrf2 signaling pathway and activation of Msr prevent Cu-induced nephrotoxicity and attenuate oxidative damage.

Ameliorative Effects of Gallic Acid on Cisplatin-Induced Nephrotoxicity in Rat Variations of Biochemistry, Histopathology, and Gene Expression

BACKGROUND

Cisplatin is a powerful chemotherapeutic drug mainly used in the treatment of solid tumors. Aggregation of the drug in renal proximal tubule cells causes nephrotoxicity and renal failure. Investigations showed nephrotoxicity as Cisplatin's dose-limiting side effect. One of the Cisplatin toxicity mechanisms is generation of reactive oxygen species, which leads to oxidative stress and renal damage. The purpose of this study was evaluation of the modulating effects of Gallic acid on Cisplatin-induced variations including Caspase-3 and Clusterin expression and histopathological and biochemical parameters in adult male Wistar rats.

METHOD

Rats were kept under standard condition of temperature, light, and humidity. The animals were divided into 4 groups: GpI: control group (received distilled water for 10 days); GpII: Gallic acid (alone) (50 mg/kg bw, once a day for 10 days); GpIII: Cisplatin (alone), single dose (6 mg/kg bw, I.P. on 5th day of study); GpIV: Gallic acid (50 mg/kg bw, once a day for 10 days) and also injected with single dose of Cisplatin (6 mg/kg bw, I.P., on 5th day of study). After 10 days, all rats were anaesthetized and plasma collected to estimate urea, creatinine, and uric acid. The right kidneys were removed for the study of gene expression and biochemical parameters. The left kidneys were used for histopathological studies.

RESULTS

The Cisplatin-induced nephrotoxicity was evident from the elevated levels of creatinine, urea, uric acid, and renal tissue MDA and also decreased levels of SOD, CAT, GPX, and GSH in renal tissue. Administration of Gallic acid significantly modulated nephrotoxicity markers, gene expression variations, and histopathological damage.

CONCLUSION

Outcomes of the present investigation suggest that Gallic acid provides protection against CP-induced nephrotoxicity, but for application in people, further studies are needed.

The Role of Mitochondria in Acute Kidney Injury and Chronic Kidney Disease and Its Therapeutic Potential

Mitochondria are heterogeneous and highly dynamic organelles, playing critical roles in adenosine triphosphate (ATP) synthesis, metabolic modulation, reactive oxygen species (ROS) generation, and cell differentiation and death. Mitochondrial dysfunction has been recognized as a contributor in many diseases. The kidney is an organ enriched in mitochondria and with high energy demand in the human body. Recent studies have been focusing on how mitochondrial dysfunction contributes to the pathogenesis of different forms of kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD). AKI has been linked to an increased risk of developing CKD. AKI and CKD have a broad clinical syndrome and a substantial impact on morbidity and mortality, encompassing various etiologies and representing important challenges for global public health.&nbsp;Renal mitochondrial disorders are a common feature of diverse forms of AKI and CKD, which result from defects in mitochondrial structure, dynamics, and biogenesis as well as crosstalk of mitochondria with other organelles. Persistent dysregulation of mitochondrial homeostasis in AKI and CKD affects diverse cellular pathways, leading to an increase in renal microvascular loss, oxidative stress, apoptosis, and eventually renal failure. It is important to understand the cellular and molecular events that govern mitochondria functions and pathophysiology in AKI and CKD, which should facilitate the development of novel therapeutic strategies. This review provides an overview of the molecular insights of the mitochondria and the specific pathogenic mechanisms of mitochondrial dysfunction in the progression of AKI, CKD, and AKI to CKD transition. We also discuss the possible beneficial effects of mitochondrial-targeted therapeutic agents for the treatment of mitochondrial dysfunction-mediated AKI and CKD, which may translate into therapeutic options to ameliorate renal injury and delay the progression of these kidney diseases.

Mitochondrial Redox Signaling and Oxidative Stress in Kidney Diseases

Mitochondria are essential organelles in physiology and kidney diseases, because they produce cellular energy required to perform their function. During mitochondrial metabolism, reactive oxygen species (ROS) are produced. ROS function as secondary messengers, inducing redox-sensitive post-translational modifications (PTM) in proteins and activating or deactivating different cell signaling pathways. However, in kidney diseases, ROS overproduction causes oxidative stress (OS), inducing mitochondrial dysfunction and altering its metabolism and dynamics. The latter processes are closely related to changes in the cell redox-sensitive signaling pathways, causing inflammation and apoptosis cell death. Although mitochondrial metabolism, ROS production, and OS have been studied in kidney diseases, the role of redox signaling pathways in mitochondria has not been addressed. This review focuses on altering the metabolism and dynamics of mitochondria through the dysregulation of redox-sensitive signaling pathways in kidney diseases.

Methionine sulfoxide and the methionine sulfoxide reductase system as modulators of signal transduction pathways: a review

Methionine oxidation and reduction is a common phenomenon occurring in biological systems under both physiological and oxidative-stress conditions. The levels of methionine sulfoxide (MetO) are dependent on the redox status in the cell or organ, and they are usually elevated under oxidative-stress conditions, aging, inflammation, and oxidative-stress related diseases. MetO modification of proteins may alter their function or cause the accumulation of toxic proteins in the cell/organ. Accordingly, the regulation of the level of MetO is mediated through the ubiquitous and evolutionary conserved methionine sulfoxide reductase (Msr) system and its associated redox molecules. Recent published research has provided new evidence for the involvement of free MetO or protein-bound MetO of specific proteins in several signal transduction pathways that are important for cellular function. In the current review, we will focus on the role of MetO in specific signal transduction pathways of various organisms, with relation to their physiological contexts, and discuss the contribution of the Msr system to the regulation of the observed MetO effect.

Catalpol-Induced AMPK Activation Alleviates Cisplatin-Induced Nephrotoxicity through the Mitochondrial-Dependent Pathway without Compromising Its Anticancer Properties

Nephrotoxicity is a common complication of cisplatin chemotherapy and, thus, limits the clinical application of cisplatin. In this work, the effects of catalpol (CAT), a bioactive ingredient extracted from Rehmannia glutinosa, on cisplatin-induced nephrotoxicity and antitumor efficacy were comprehensively investigated. Specifically, the protective effect of CAT on cisplatin-induced injury was explored in mice and HK-2 cells. In vivo, CAT administration strikingly suppressed cisplatin-induced renal dysfunction, morphology damage, apoptosis, and inflammation. In vitro, CAT induced activation of adenosine 5′-monophosphate- (AMP-) activated protein kinase (AMPK), improved mitochondrial function, and decreased generation of cellular reactive oxygen species (ROS), leading to a reduction in inflammation and apoptosis, which ultimately protected from cisplatin-induced injury. However, the beneficial effects of CAT were mostly blocked by coincubation with compound C. Furthermore, molecular docking results indicated that CAT had a higher affinity for AMPK than other AMPK activators such as danthron, phenformin, and metformin. Importantly, CAT possessed the ability to reverse drug resistance without compromising the antitumor properties of cisplatin. These findings suggest that CAT exerts positive effects against cisplatin-induced renal injury through reversing drug resistance via the mitochondrial-dependent pathway without affecting the anticancer activity of cisplatin.

Wnt/β-catenin agonist BIO alleviates cisplatin-induced nephrotoxicity without compromising its efficacy of anti-proliferation in ovarian cancer

AIMS

Cisplatin is an anticancer agent marred by nephrotoxicity. Limiting this adverse effect may allow the use of higher doses to improve its efficacy. The Wnt/β-catenin signaling pathway plays a critical role in nephrogenesis and repair of renal diseases. BIO, a small molecule agonist of this pathway, exerted a protective effect in adriamycin nephropathy and promoted nephrogenesis. The aim of this study, therefore, was to investigate whether Wnt/β-catenin agonist BIO could protect against cisplatin-induced nephrotoxicity in vivo and in vitro, as well as its possible mechanism.

MAIN METHODS

Male mice and human renal proximal tubular cells (HK-2) were subjected to cisplatin to study reno-protective effect of BIO. Renal function, cell viability, tubular apoptosis, production of reactive oxygen species (ROS) and proliferative level were analyzed respectively. Additionally, xenograft model was induced to investigate if BIO would impair the antitumor effect of cisplatin.

KEY FINDINGS

Cisplatin increased serum creatinine levels and promoted histological renal injury as well as oxidative stress levels. Besides, renal apoptotic level and the expression of pro-apoptotic proteins, Bax/bcl-2 and cleaved-caspase3 included, in the kidney were increased. All these features were decreased by BIO, which also activated Wnt/β-catenin pathway in cisplatin-induced nephrotoxicity. Similarly, accompanied by the motivation of Wnt/β-catenin pathway, BIO exerted a positively protective effect on HK-2 challenged cisplatin. Last, the chemotherapeutic effects of cisplatin in xenograft mice of ovary tumor models and in lung cancer cells weren't compromised by BIO.

SIGNIFICANCE

Wnt/β-catenin agonist BIO has the potential to prevent cisplatin nephrotoxicity without compromising its anti-proliferation efficacy.

Effects of power frequency electric field exposure on kidney

With the rapid development of ultra high voltage alternating current (UHV AC) transmission, the intensity of environmental power frequency electric field (PFEF) near UHV AC transmission lines increased continuously, which has attracted considerable public attention on the potential health effects of PFEF. In this study, the effect of PFEF exposure on the kidney was explored. Institute of Cancer Research (ICR) mice were exposed to 35 kV/m PFEF (50 Hz). Two indicators relating to renal function (urea nitrogen and creatinine) were tested after the exposure of 7d, 14d, 21d, 35d and 49d. The pathological morphology and cellular ultrastructure of kidney were observed respectively by light microscopy and electron microscopy after the exposure of 25d and 52d. Results showed that compared with that of the control group, the concentration of urea nitrogen of 35 kV/m PFEF exposure group significantly increased on the 21st and 35th days, and the concentration of creatinine significantly increased on the 14th, 21st and 35th days. However, the concentrations of creatinine and urea nitrogen both returned to normal levels on the 49th day. Furthermore, an enlarged Bowman's space, the vacuolation of renal tubular epithelial cells and the foot process effacement of podocyte were found after 25d exposure, but no abnormality was observed after 52d exposure. Obviously, a short-term (35d) exposure of 35 kV/m PFEF could cause kidney injury, which could be recovered after a longer-term (52d) exposure. Based on this study and relevant literatures, one explanation for this two-way effect is as follows. Kidney injury was caused by the disequilibrium of mitochondrial dynamics under 35 kV/m PFEF exposure. PFEF could also activate Wnt/β-catenin signal to promote the recovery of renal tubular epithelial cells and glomerular podocytes, so kidney injury could be repaired.

Isocitrate dehydrogenase 2 deficiency aggravates prolonged high-fat diet intake-induced hypertension

The development of hypertension is associated with mitochondrial redox balance disruptions. NADP⁺-dependent isocitrate dehydrogenase 2 (IDH2) plays an important role in the maintenance of mitochondrial redox balance by producing mitochondrial NADPH, which is an essential cofactor in the reduction of glutathione (from GSSG to GSH) to reduced form of glutathione (GSH). We investigated the association of IDH2 between the development of prolonged high-fat diet (HFD)-induced hypertension. Idh2 gene-deleted (Idh2^-/-) male mice and wild-type (Idh2^+/+) littermates were fed either HFD or low-fat diet (LFD). Some mice were administrated with Mito-TEMPO, a mitochondria-specific antioxidant. HFD feeding increased blood pressure (BP) in both Idh2^-/- mice and Idh2^+/+ mice. HFD-induced BP increase was greater in Idh2^-/- than Idh2^+/+ mice. HFD intake decreased IDH2 activity, NADPH levels, and the GSH/(GSH + GSSG) ratio in the renal mitochondria. However, HFD intake increased mitochondrial ROS levels, along with the accompanying oxidative stress and damage. HFD intake increased angiotensin II receptor 1 type 1 mRNA levels in the kidneys and plasma renin and angiotensin II concentrations. These HFD-induced changes were more prominent in Idh2^-/- mice than Idh2^+/+ mice. Mito-TEMPO mitigated the HFD-induced changes in both Idh2^-/- and Idh2^+/+ mice, with greater effects in Idh2^-/- mice than Idh2^+/+ mice. These results indicate that prolonged HFD intake disrupts the IDH2-NADPH-GSH-associated antioxidant system and activates the renin-angiotensin system in the kidney, leading to increased BP, suggesting that IDH2 is a critical enzyme in the development of hypertension and that the IDH2-associated antioxidant system could serve as a potential hypertension treatment target.

Mitochondrial-targeted methionine sulfoxide reductase overexpression increases the production of oxidative stress in mitochondria from skeletal muscle

Objective:

Mitochondrial dysfunction comprises part of the etiology of myriad health issues, particularly those that occur with advancing age. Methionine sulfoxide reductase A (MsrA) is a ubiquitous protein oxidation repair enzyme that specifically and catalytically reduces a specific epimer of oxidized methionine: methionine sulfoxide. In this study, we tested the ways in which mitochondrial bioenergetic functions are affected by increasing MsrA expression in different cellular compartments.

Methods:

In this study, we tested the function of isolated mitochondria, including free radical generation, ATP production, and respiration, from the skeletal muscle of two lines of transgenic mice with increased MsrA expression: mitochondria-targeted MsrA overexpression or cytosol-targeted MsrA overexpression.

Results:

Surprisingly, in the samples from mice with mitochondrial-targeted MsrA overexpression, we found dramatically increased free radical production though no specific defect in respiration, ATP production, or membrane potential. Among the electron transport chain complexes, we found the activity of complex I was specifically reduced in mitochondrial MsrA transgenic mice. In mice with cytosolic-targeted MsrA overexpression, we found no significant alteration made to any of these parameters of mitochondrial energetics.

Conclusions:

There is also a growing amount of evidence that MsrA is a functional requirement for sustaining optimal mitochondrial respiration and free radical generation. MsrA is also known to play a partial role in maintaining normal protein homeostasis by specifically repairing oxidized proteins. Our studies highlight a potential novel role for MsrA in regulating the activity of mitochondrial function through its interaction with the mitochondrial proteome.

Panax notoginseng saponins ameliorate cisplatin-induced mitochondrial injury via the HIF-1α/mitochondria/ROS pathway

Cisplatin is a major antineoplastic drug that is used to treat solid tumors, but its use is restricted by its nephrotoxicity. Such cisplatin‐induced nephrotoxicity (CIN) is believed to occur primarily through mitochondrial damage and reactive oxygen species (ROS) generation. Our previous studies have indicated that Panax notoginseng saponins (PNSs) mitigate CIN by enhancing hypoxia‐inducible factor 1α (HIF‐1α)‐induced mitochondrial autophagy. In this study, the role of the HIF‐1α/mitochondria/ROS pathway in PNSs protection against CIN was investigated using a rat model. A CIN model was generated by giving rats intraperitoneal injections with cisplatin (a single dose) and then treating them with or without 2‐methoxyestradiol (HIF‐1α inhibitor) and PNSs. We then measured ROS levels, superoxide dismutase, glutathione, catalase malondialdehyde and nitric oxide (to evaluate oxidative stress) and ATP, mitochondrial membrane potential and mitochondrial permeability transition pore opening (to evaluate mitochondrial function) in kidneys at different time points. We observed that PNSs remarkably reduced the levels of ROS, malondialdehyde and nitric oxide, as well as the opening of mitochondrial permeability transition pore, which is increased by cisplatin and further increased by HIF‐1α inhibition. In addition, PNSs increased the levels of superoxide dismutase, catalase and glutathione, as well as ATP and mitochondrial membrane potential in renal tissues; these are all reduced by cisplatin and further reduced by HIF‐1α inhibition. In conclusion, we demonstrate here that PNSs protects against mitochondrial damage induced by cisplatin through HIF‐1α/mitochondria/ROS.

Loss of methionine sulfoxide reductases increases resistance to oxidative stress

Oxidation of methionine residues to methionine sulfoxide scavenges reactive species, thus protecting against oxidative stress. Reduction of the sulfoxide back to methionine by methionine sulfoxide reductases creates a cycle with catalytic efficiency. Protection by the methionine sulfoxide reductases is well documented in cultured cells, from microorganisms to mammals. However, knocking out one or two of the 4 mammalian reductases had little effect in mice that were not stressed. We hypothesized that the minimal effect is due to redundancy provided by the 4 reductases. We tested the hypothesis by creating a transgenic mouse line lacking all 4 reductases and predicted that this mouse would be exceptionally sensitive to oxidative stress. The mutant mice were phenotypically normal at birth, exhibited normal post-natal growth, and were fertile. Surprisingly, rather than being more sensitive to oxidative stress, they were more resistant to both cardiac ischemia-reperfusion injury and to parenteral paraquat, a redox-cycling agent. Resistance was not a result of hormetic induction of the antioxidant transcription factor Nrf2 nor activation of Akt. The mechanism of protection may be novel.

S-Sulfhydration of SIRT3 by Hydrogen Sulfide Attenuates Mitochondrial Dysfunction in Cisplatin-Induced Acute Kidney Injury

Aims: Clinical use of cisplatin (Cisp), one of the most widely used, common, and effective chemotherapeutic agents, is limited by its side effects, particularly tubular injury-associated nephrotoxicity. Previous studies suggest that hydrogen sulfide (H₂S) alleviates Cisp-induced acute kidney injury (AKI). However, the underlying mechanism remains largely unclear. Results: A single intraperitoneal injection of Cisp is employed to induce AKI, and the mice exhibit severe kidney dysfunction and histological damage at day 4 after Cisp injection. Here, we reported that H₂S alleviated Cisp-caused renal toxicity via SIRT3 activation and subsequent improvement of mitochondrial ATP production. Using a biotin-switch assay, we showed that H₂S increased S-sulfhydration of SIRT3 and induced deacetylation of its target proteins (OPA1, ATP synthase β, and superoxide dismutase 2). These effects of H₂S were associated with a reduction of mitochondrial fragmentation, an increase in ATP generation, and less oxidative injury. Notably, the S-sulfhydration of SIRT3 induced by H₂S was abrogated when Cys256, Cys259, Cys280, and Cys283 residues on SIRT3 (two zinc finger domains) were mutated. Innovation and Conclusion: Our data suggest that H₂S attenuates Cisp-induced AKI by preventing mitochondrial dysfunction via SIRT3 sulfhydrylation. Antioxid. Redox Signal. 31, 1302-1319.

Drugs Repurposed as Antiferroptosis Agents Suppress Organ Damage, Including AKI, by Functioning as Lipid Peroxyl Radical Scavengers

BACKGROUND

Ferroptosis, nonapoptotic cell death mediated by free radical reactions and driven by the oxidative degradation of lipids, is a therapeutic target because of its role in organ damage, including AKI. Ferroptosis-causing radicals that are targeted by ferroptosis suppressors have not been unequivocally identified. Because certain cytochrome P450 substrate drugs can prevent lipid peroxidation via obscure mechanisms, we evaluated their antiferroptotic potential and used them to identify ferroptosis-causing radicals.

METHODS

Using a cell-based assay, we screened cytochrome P450 substrate compounds to identify drugs with antiferroptotic activity and investigated the underlying mechanism. To evaluate radical-scavenging activity, we used electron paramagnetic resonance-spin trapping methods and a fluorescence probe for lipid radicals, NBD-Pen, that we had developed. We then assessed the therapeutic potency of these drugs in mouse models of cisplatin-induced AKI and LPS/galactosamine-induced liver injury.

RESULTS

We identified various US Food and Drug Administration-approved drugs and hormones that have antiferroptotic properties, including rifampicin, promethazine, omeprazole, indole-3-carbinol, carvedilol, propranolol, estradiol, and thyroid hormones. The antiferroptotic drug effects were closely associated with the scavenging of lipid peroxyl radicals but not significantly related to interactions with other radicals. The elevated lipid peroxyl radical levels were associated with ferroptosis onset, and known ferroptosis suppressors, such as ferrostatin-1, also functioned as lipid peroxyl radical scavengers. The drugs exerted antiferroptotic activities in various cell types, including tubules, podocytes, and renal fibroblasts. Moreover, in mice, the drugs ameliorated AKI and liver injury, with suppression of tissue lipid peroxidation and decreased cell death.

CONCLUSIONS

Although elevated lipid peroxyl radical levels can trigger ferroptosis onset, some drugs that scavenge lipid peroxyl radicals can help control ferroptosis-related disorders, including AKI.

Relation of Redox and Structural Alterations of Rat Skin in the Function of Chronological Aging

Accumulation of oxidative insults on molecular and supramolecular levels could compromise renewal potency and architecture in the aging skin. To examine and compare morphological and ultrastructural changes with redox alterations during chronological skin aging, activities of antioxidant defense (AD) enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), thioredoxin reductase (TR), and methionine sulfoxide reductase A (MsrA), and the markers of oxidative damage of biomolecules-4-hydroxynonenal (HNE) and 8-oxoguanine (8-oxoG)-were examined in the rat skin during life (from 3 days to 21 months). As compared to adult 3-month-old skin, higher activities of CAT, GSH-Px, and GR and a decline in expression of MsrA are found in 21-month-old skin. These changes correspond to degenerative changes at structural and ultrastructural levels in epidermal and dermal compartments, low proliferation capacity, and higher levels of HNE-modified protein aldehydes (particularly in basal lamina) and 8-oxoG positivity in nuclei and mitochondria in the sebaceous glands and root sheath. In 3-day-old skin, higher activities of AD enzymes (SOD, CAT, GR, and TR) and MsrA expression correspond to intensive postnatal development and proliferation. In contrast to 21-month-old skin, a high level of HNE in young skin is not accompanied by 8-oxoG positivity or any morphological disturbances. Observed results indicate that increased activity of AD enzymes in elderly rat skin represents the compensatory response to accumulated oxidative damage of DNA and proteins, accompanied by attenuated repair and proliferative capacity, but in young rats the redox changes are necessary and inherent with processes which occur during postnatal skin development. Мorphological and ultrastructurаl changes are in line with the redox profile in the skin of young and old rats.

Genetic regulation of longevity and age-associated diseases through the methionine sulfoxide reductase system

Methionine sulfoxide reductase enzymes are a protective system against biological oxidative stress in aerobic organisms. Modifications to this antioxidant system have been shown to impact the lifespan of several model system organisms. In humans, methionine oxidation of critical proteins and deficiencies in the methionine sulfoxide reductase system have been linked to age-related diseases, including cancer and neurodegenerative disease. Substrates for methionine sulfoxide reductases have been reviewed multiple times, and are still an active area of discovery. In contrast, less is known about the genetic regulation of methionine sulfoxide reductases. In this review, we discuss studies on the genetic regulation of the methionine sulfoxide reductase system with relevance to longevity and age-related diseases. A better understanding of genetic regulation for methionine sulfoxide reductases may lead to new therapeutic approaches for age-related diseases in the future.

The Functions of the Mammalian Methionine Sulfoxide Reductase System and Related Diseases

This review article describes and discusses the current knowledge on the general role of the methionine sulfoxide reductase (MSR) system and the particular role of MSR type A (MSRA) in mammals. A powerful tool to investigate the contribution of MSRA to molecular processes within a mammalian system/organism is the MSRA knockout. The deficiency of MSRA in this mouse model provides hints and evidence for this enzyme function in health and disease. Accordingly, the potential involvement of MSRA in the processes leading to neurodegenerative diseases, neurological disorders, cystic fibrosis, cancer, and hearing loss will be deliberated and evaluated.

Thioredoxin promotes survival signaling events under nitrosative/oxidative stress associated with cancer development

Accumulating mutations may drive cells into the acquisition of abnormal phenotypes that are characteristic of cancer cells. Cancer cells feature profound alterations in proliferation programs that result in a new population of cells that overrides normal tissue construction and maintenance programs. To achieve this goal, cancer cells are endowed with up regulated survival signaling pathways. They also must counteract the cytotoxic effects of high levels of nitric oxide (NO) and of reactive oxygen species (ROS), which are by products of cancer cell growth. Accumulating experimental evidence associates cancer cell survival with their capacity to up-regulate antioxidant systems. Elevated expression of the antioxidant protein thioredoxin-1 (Trx1) has been correlated with cancer development. Trx1 has been characterized as a multifunctional protein, playing different roles in different cell compartments. Trx1 migrates to the nucleus in cells exposed to nitrosative/oxidative stress conditions. Trx1 nuclear migration has been related to the activation of transcription factors associated with cell survival and cell proliferation. There is a direct association between the p21Ras-ERK1/2 MAP Kinases survival signaling pathway and Trx1 nuclear migration under nitrosative stress. The expression of the cytoplasmic protein, the thioredoxin-interacting protein (Txnip), determines the change in Trx1 cellular compartmentalization. The anti-apoptotic actions of Trx1 and its denitrosylase activity occur in the cytoplasm and serve as important regulators of cell survival. Within this context, this review focuses on the participation of Trx1 in cells under nitrosative/oxidative stress in survival signaling pathways associated with cancer development.