Inhibition Of Mitochondrial Dysfunction Research Articles

Qiangxinyin formula protects against isoproterenol-induced cardiac hypertrophy

Heart failure is a life-threatening cardiovascular disease and characterized by cardiac hypertrophy, inflammation and fibrosis. The traditional Chinese medicine formula Qiangxinyin (QXY) is effective for the treatment of heart failure while the underlying mechanism is not clear. This study aims to identify the active ingredients of QXY and explore its mechanisms protecting against cardiac hypertrophy. We found that QXY significantly protected against isoproterenol (ISO)-induced cardiac hypertrophy and dysfunction in zebrafish. Eight compounds, including benzoylmesaconine (BMA), atractylenolide I (ATL I), icariin (ICA), quercitrin (QUE), psoralen (PRN), kaempferol (KMP), ferulic acid (FA) and protocatechuic acid (PCA) were identified from QXY. PRN, KMP and icaritin (ICT), an active pharmaceutical ingredient of ICA, prevented ISO-induced cardiac hypertrophy and dysfunction in zebrafish. In H9c2 cardiomyocyte treated with ISO, QXY significantly blocked the calcium influx, reduced intracellular lipid peroxidative product MDA, stimulated ATP production and increased mitochondrial membrane potential. QXY also inhibited ISO-induced cardiomyocyte hypertrophy and cytoskeleton reorganization. Mechanistically, QXY enhanced the phosphorylation of Smad family member 2 (SMAD2) and myosin phosphatase target subunit-1 (MYPT1), and suppressed the phosphorylation of myosin light chain (MLC). In conclusion, PRN, KMP and ICA are the main active ingredients of QXY that protect against ISO-induced cardiac hypertrophy and dysfunction largely via the blockage of calcium influx and inhibition of mitochondrial dysfunction as well as cytoskeleton reorganization.

Targeted inhibition of colorectal cancer proliferation: Thedual-modulatory role of 2,4-DTBP on anti-apoptotic Bcl-2 and Survivin proteins.

The anti-apoptotic proteins, Bcl-2 and Survivin, are consistently overexpressed in numerous human malignancies, notably in colorectal cancer. 2,4-Di-tert-butylphenol (2,4-DTBP) is a naturally occurring phenolic compound known for its diverse biological activities, including anti-cancer properties. The mechanism behind 2,4-DTBP-induced inhibition of cell proliferation and apoptosis in human colorectal cancer cells, specifically regarding Bcl-2 and Survivin, remains to be elucidated. In this study, we employed both in silico and invitro methodologies to underpin this interaction at the molecular level. Molecular docking demonstrated a substantial binding affinity of 2,4-DTBP towards Bcl-2 (ΔG = -9.8 kcal/mol) and Survivin (ΔG = -5.6 kcal/mol), suggesting a potential inhibitory effect. Further, molecular dynamic simulations complemented by MM-GBSA calculations confirmed the significant binding of 2,4-DTBP with Bcl-2 (dGbind = -54.85 ± 6.79 kcal/mol) and Survivin (dGbind = -32.36 ± 1.29 kcal/mol). Invitro assays using HCT116 colorectal cancer cells revealed that 2,4-DTBP inhibited proliferation and promoted apoptosis in both a dose- and time-dependent manner. Fluorescence imaging and scanning electron microscopy illustrated the classical features associated with apoptosis upon 2,4-DTBP exposure. Cell cycle analysis through flow cytometry highlighted a G1 phase arrest and apoptosis assay demonstrated increased apoptotic cell population. Notably, western blotting results indicated a decreased expression of Bcl-2 and Survivin post-treatment. Considering the cytoprotective roles of Bcl-2 and Survivin through the inhibition of mitochondrial dysfunction, our findings of disrupted mitochondrial bioenergetics, characterized by reduced ATP production and oxygen consumption, further accentuate the functional impairment of these proteins. Overall, the integration of in silico and invitro data suggests that 2,4-DTBP holds promise as a therapeutic agent targeting Bcl-2 and Survivin in colorectal cancer.

Soluble epoxide hydrolase gene deletion ameliorates retinal and ophthalmic arterial senescesome

Aims/Purpose: Neurovascular dysfunction in glaucoma is exacerbated by aging. We recently deciphered the crucial role of the cytochrome P450 (CYP) metabolic pathway in the retina (R) and ophthalmic artery (OA). Vasoactive CYP metabolites are hydrolysed by soluble epoxide hydrolase (sEH), thereby diminishing their protective effects. Hence, sEH has emerged as a novel inhibitory target. This study defined the neuro‐vasculoprotective molecular signatures of Ephx2 gene deletion (KO) that impinge senescence in the neural R and OA.Methods: Retinae and OA were isolated from young (3–5 months) and old (12–24 months) male wild type (WT) and KO mice. Samples were pooled (n = 5 mice/group/replicate) to yield 4 biological replicates per group and subjected to label‐free mass spectrometry‐based proteomics and in‐silico bioinformatics analyses.Results: A total of 3706 retinal and 644 OA proteins were identified. Aging profoundly affected the R and OA proteome of WT mice, as demonstrated by the differential expressions of 183 and 111 proteins, respectively. The key changes attributed to age‐related R cellular dysfunction and DNA damage were reflected in the inactivation of NAD+ (p = 9.1 × 10−4) and sirtuin (p = 6.2 × 10−3) signalling pathways. Remarkably, KO had a major influence on the regulation of R proteins involved in bioenergetics reprogramming via mitochondrial homeostasis in young mice, which was shown by the activation of oxidative phosphorylation (p = 1.3 × 10−6) and inhibition of mitochondrial dysfunction (p = 3.4 × 10−3), both of which corresponded to upstream involvement of UQCC3 (p = 7.3 × 10−7). A translation regulator, LARP1, which regulates cell proliferation and protein synthesis, was highly activated in the aged KO retina (p = 10 × 10−16) compared to aged WT (p = 3.1 × 10−5). In the OA, vascular remodelling processes observed in the aged WT mice, primarily compromised microtubule dynamics (3.6 × 10−8) and cell–cell contact (3.7 × 10−6), were significantly attenuated in the KO. Noteworthy, KO significantly mitigated proteome changes attributed to inflammatory response in the OA of both young and aged mice.Conclusions: In gist, the Ephx2 gene deletion significantly ameliorated detrimental senescesome in ocular neurovascular tissues. The potential use of sEH inhibitors for glaucoma needs further investigation.

Allicin Alleviates Mitochondrial Dysfunction in Acrylamide-Induced Rat Kidney Involving the Regulation of SIRT1.

Acrylamide (AA), commonly formed in carbohydrate-rich thermally processed foods, exerts harmful effects on the kidney. Allicin, from crushed garlic cloves, exhibits strong biological activities. In the current study, the protection mechanisms of allicin against AA-caused nephrotoxicity were comprehensively examined using an in vivo rat model based on previous research that allicin plays a key role in improving renal function. The results showed that allicin attenuated histological changes of the kidney and ameliorated renal function. Damaged mitochondrial structures, upregulated voltage-dependent anion channel 1 expression, and decreased membrane potential and adenosine 5'-triphosphate levels were observed after AA treatment. Surprisingly, allicin notably reversed the adverse effects. Further, allicin effectively restored mitochondrial function via modulating mitochondrial biogenesis and dynamics, which might be associated with the upregulated expression of sirtuin 1 (SIRT1). Meanwhile, allicin dramatically activated the SIRT1 activity and subsequently inhibited p53 acetylation, prevented the translocation of cytochrome c to the cytoplasm, and reduced the caspase expression, thus further inhibiting mitochondrial apoptosis caused by AA. In summary, the relieving effect of allicin on AA-caused nephrotoxicity lies in its inhibition of mitochondrial dysfunction and mitochondrial apoptosis.

Flavonoids from Hippophae rhamnoides Linn. Revert Doxorubicin-Induced Cardiotoxicity through Inhibition of Mitochondrial Dysfunction in H9c2 Cardiomyoblasts In Vitro

Doxorubicin (Dox) is one of the most frequently prescribed anti-cancer drugs. However, treatment with Dox is limited due to cumulative cardiotoxicity. 3-O-β-d-Sophorosylkaempferol-7-O-{3-O-[2(E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl]}-α-L-rhamnoside (F-A), kaempferol 3-sophoroside 7-rhamnoside (F-B), and hippophanone (F-C) were successfully obtained by purification and separation of seabuckthorn seed residue in our previous research. This study was undertaken to investigate the protective effect of three flavonoids against Dox-induced H9c2 cell apoptosis. Cell proliferation was detected by MTT assay. 2',7'-Dichlorofluorescein diacetate (DCFH-DA) was used to determine the production of intracellular reactive oxygen species (ROS). ATP content was measured using an assay kit. Transmission electron microscopy (TEM) was used to observe changes in mitochondrial ultrastructure. The expression levels of proteins (p-JNK, JNK, p-Akt, Akt, p-P38, P38, p-ERK, ERK, p-Src, Src, Sab, IRE1α, Mfn1, Mfn2, and cleaved caspase-3) were evaluated by Western blot. Molecular docking was performed using AutoDock Vina. The three flavonoids could significantly relieve Dox-induced cardiac injury and inhibit cardiomyocyte apoptosis. The mechanisms were mainly related to the stability of mitochondrial structure and function maintained by suppressing the production of intracellular ROS, p-JNK and cleaved caspase-3, and increasing ATP contents and protein expression of mitochondrial mitofusin (Mfn1, Mfn2), Sab and p-Src. Pretreatment with flavonoids from Hippophae rhamnoides Linn. can reduce Dox-induced H9c2 cell apoptosis based on the 'JNK-Sab-Ros' signal pathway.

Protective effect of natural products in the metabolic-associated kidney diseases via regulating mitochondrial dysfunction.

Metabolic syndrome (MS) is a complex group of metabolic disorders syndrome with hypertension, hyperuricemia and disorders of glucose or lipid metabolism. As an important organ involved in metabolism, the kidney is inevitably attacked by various metabolic disorders, leading to abnormalities in kidney structure and function. Recently, an increasing number of studies have shown that mitochondrial dysfunction is actively involved in the development of metabolic-associated kidney diseases. Mitochondrial dysfunction can be used as a potential therapeutic strategy for the treatment of metabolic-associated kidney diseases. Many natural products have been widely used to improve the treatment of metabolic-associated kidney diseases by inhibiting mitochondrial dysfunction. In this paper, by searching several authoritative databases such as PubMed, Web of Science, Wiley Online Library, and Springer Link. We summarize the Natural Products Protect Against Metabolic-Associated Kidney Diseases by Regulating Mitochondrial Dysfunction. In this review, we sought to provide an overview of the mechanisms by which mitochondrial dysfunction impaired metabolic-associated kidney diseases, with particular attention to the role of mitochondrial dysfunction in diabetic nephropathy, gouty nephropathy, hypertensive kidney disease, and obesity-related nephropathy, and then the protective role of natural products in the kidney through inhibition of mitochondrial disorders, thus providing a systematic understanding of the targets of mitochondrial dysfunction in metabolic-associated kidney diseases, and finally a review of promising therapeutic targets and herbal candidates for metabolic-associated kidney diseases through inhibition of mitochondrial dysfunction.

Notch1 Protects against Ischemic-Reperfusion Injury by Suppressing PTEN-Pink1-Mediated Mitochondrial Dysfunction and Mitophagy.

Myocardial ischemia/reperfusion injury is associated with adverse cardiovascular outcomes after acute myocardial infarction. However, the molecular mechanism of ischemia/reperfusion injury remains unclear. Mitochondria dysfunction is a participant in and regulator of myocardial ischemia-reperfusion injury. However, the molecular mechanisms involved in this process are not yet fully understood. We previously reported that Notch1 can reduce mitochondrial lysis, reduce myocardial infarct size, and inhibit ventricular remodeling. Herein, we explore the role of the downstream target Notch1 in mitochondrial regulation. This study constructs an ischemic/reperfusion injury rat model and a hypoxia/reoxygenation cell model. The expression of PTEN is detected by real-time PCR, Western blot, and immunofluorescence staining. Cell viability is analyzed with CCK-8. Apoptosis level is detected via the TUNEL assay, and mitochondrial fission/fusion is analyzed with MitoTracker Green staining. Cardiac troponin I (cTnI), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and CK levels of creatine kinase-MB (CK) are measured with ELISA kits. We found that PETN-Pink1-Parkin signaling is inhibited by Notch1 I/R in injured neonatal cardiomyocytes and hearts, i.e., via the inhibition of mitochondrial dysfunction and fragmentation. With the recure of PTEN or Pink1, the protective effect of Notch1 was largely diminished. These results suggest that N1ICD acts protectively against ischemic reperfusion injury by suppressing PTEN-Pink1-mediated mitochondrial dysfunction and fragmentation.

Proteomic analysis of zearalenone toxicity on mouse thymic epithelial cells.

Zearalenone (ZEA) is one of the most major food contaminants in cereal crops worldwide, risking health of both livestock and humans. This study aimed to assess the cytotoxicity and the underlying mechanism of ZEA on thymic epithelial cells. By using proteomics analysis, we identified 596 differentially expressed proteins in MTEC1 cells upon zearalenone exposure, of which 245 were upregulated and 351 were downregulated. Gene ontology (GO) analysis suggested that differentially expressed proteins were participated in protein synthesis, oxidative phosphorylation, and ATP binding. KEGG pathway enrichment analysis showed that differentially expressed proteins were mainly related to mitochndrial metabolism, such as citrate cycle (TCA cycle) and oxidative phosphorylation. We demonstrated that ZEA treatment was able to increase the intracellular reactive oxygen species (ROS) level, to decrease ΔΨm, ATP level, and the copy number of mtDNA, leading to necrotic cell death. Moreover, we showed that ZEA treatment inhibited cell proliferation and induced G2/M phase arrest by downregulation of proliferation-associated proteins ERK, p-ERK, CDK1, and p-CHK1. Taken together, we found that the toxicity of ZEA on thymic epithelial cells is mainly caused by the inhibition of mitochondrial dysfunction and cell proliferation. Our study might open new avenues for treatment strategies.

HDAC6 promotes sepsis development by impairing PHB1-mediated mitochondrial respiratory chain function.

Objective: This study was aimed at investigating the regulation of mitochondrial function by histone deacetylase 6 (HDAC6) and the role of HDAC6 in the development and progression of sepsis.Results: HDAC6 downregulated PHB1 and subsequently promoted the development of CLP-induced sepsis. Inhibition of HDAC6 significantly attenuated CLP-induced sepsis through inhibition of mitochondrial dysfunction and reduced oxidant production, thus protecting the rats from oxidative injury.Conclusions: In this sepsis model, HDAC6 inhibits the expression and function of PHB1 and alters the function of the mitochondrial respiratory chain mediated by PHB1, thus enhancing the production of oxidants and increasing oxidative stress and thereby leading to severe oxidative injury in multiple organs.Methods: The expression of HDAC6 and prohibitin 1 (PHB1) in humans and in a rat model of sepsis was measured by quantitative reverse-transcription PCR and western blotting. Sepsis induction by cecal ligation and puncture (CLP) was confirmed by histological analysis. Concentrations of different sepsis markers were measured by an enzyme-linked immunosorbent assay, and mitochondrial function was assessed via the mitochondrial respiratory control rate.

Mitochondrial dysfunction mediated through dynamin-related protein 1 (Drp1) propagates impairment in blood brain barrier in septic encephalopathy

BackgroundOut of the myriad of complications associated with septic shock, septic-associated encephalopathy (SAE) carries a significant risk of morbidity and mortality. Blood-brain-barrier (BBB) impairment, which subsequently leads to increased vascular permeability, has been associated with neuronal injury in sepsis. Thus, preventing BBB damage is an attractive therapeutic target. Mitochondrial dysfunction is an important contributor of sepsis-induced multi-organ system failure. More recently, mitochondrial dysfunction in endothelial cells has been implicated in mediating BBB failure in stroke, multiple sclerosis and in other neuroinflammatory disorders. Here, we focused on Drp1-mediated mitochondrial dysfunction in endothelial cells as a potential target to prevent BBB failure in sepsis.MethodsWe used lipopolysaccharide (LPS) to induce inflammation and BBB disruption in a cell culture as well as in murine model of sepsis. BBB disruption was assessed by measuring levels of key tight-junction proteins. Brain cytokines levels, oxidative stress markers, and activity of mitochondrial complexes were measured using biochemical assays. Astrocyte and microglial activation were measured using immunoblotting and qPCR. Transwell cultures of brain microvascular endothelial cells co-cultured with astrocytes were used to assess the effect of LPS on expression of tight-junction proteins, mitochondrial function, and permeability to fluorescein isothiocyanate (FITC) dextran. Finally, primary neuronal cultures exposed to LPS were assessed for mitochondrial dysfunction.ResultsLPS induced a strong brain inflammatory response and oxidative stress in mice which was associated with increased Drp1 activation and mitochondrial localization. Particularly, Drp1-(Fission 1) Fis1-mediated oxidative stress also led to an increase in expression of vascular permeability regulators in the septic mice. Similarly, mitochondrial defects mediated via Drp1-Fis1 interaction in primary microvascular endothelial cells were associated with increased BBB permeability and loss of tight-junctions after acute LPS injury. P110, an inhibitor of Drp1-Fis1 interaction, abrogated these defects, thus indicating a critical role for this interaction in mediating sepsis-induced brain dysfunction. Finally, LPS mediated a direct toxic effect on primary cortical neurons, which was abolished by P110 treatment.ConclusionsLPS-induced impairment of BBB appears to be dependent on Drp1-Fis1-mediated mitochondrial dysfunction. Inhibition of mitochondrial dysfunction with P110 may have potential therapeutic significance in septic encephalopathy.

Activation of SK/KCa Channel Attenuates Spinal Cord Ischemia-Reperfusion Injury via Anti-oxidative Activity and Inhibition of Mitochondrial Dysfunction in Rabbits.

Spinal cord ischemia-reperfusion injury (SCI/R) is a rare but devastating disorder with a poor prognosis. Small conductance calcium-activated K+ (SK/KCa) channels are a family of voltage-independent potassium channels that are shown to participate in the pathological process of several neurological disorders. The aim of this study was to investigate the role of SK/KCa channels in experimental SCI/R in rabbits. The expression of SK/KCa1 protein significantly decreased in both cytoplasm and mitochondria in spinal cord tissues after SCI/R. Treatment with 2 mg/kg NS309, a pharmacological activator for SK/KCa channel, attenuated SCI/R-induced neuronal loss, spinal cord edema and neurological dysfunction. These effects were still observed when the administration was delayed by 6 h after SCI/R initiation. NS309 decreased the levels of oxidative products and promoted activities of antioxidant enzymes in both serum and spinal cord tissues. The results of ELISA assay showed that NS309 markedly decreased levels of pro-inflammatory cytokines while increased anti-inflammatory cytokines levels after SCI/R. In addition, treatment with NS309 was shown to preserve mitochondrial respiratory complexes activities and enhance mitochondrial biogenesis. The results of western blot analysis showed that NS309 differentially regulated the expression of mitochondrial dynamic proteins. In summary, our results demonstrated that the SK/KCa channel activator NS309 protects against SCI/R via anti-oxidative activity and inhibition of mitochondrial dysfunction, indicating a therapeutic potential of NS309 for SCI/R.

Homoeriodictyol protects human endothelial cells against oxidative insults through activation of Nrf2 and inhibition of mitochondrial dysfunction

Excess intracellular reactive oxygen species (ROS) production is a significant causative factor of many diseases, exemplified by vascular diseases. Mitochondria are a major source of endogenous ROS, which simultaneously induce mitochondrial dysfunction. Nuclear factor-erythroid 2-related factor 2 (Nrf2) represents an important intracellular defense system that protects cells against oxidative insults caused by ROS. Therefore, molecules with the capacities of inducing Nrf2, and preventing mitochondrial dysfunction can inhibit cell apoptosis, and thus are potential drug candidates for the therapy of ROS-mediated vascular diseases. Homoeriodictyol (HE), previously isolated from Viscum articulatum Burm, has been found to be an Nrf2 inducer. In the present study, we investigated its protection on ROS-induced endothelial cell injury using a H2O2-induced human umbilical vein EA.hy926 cell oxidative insult model. Our results indicated that HE activated Nrf2 signaling pathway and protected cells against H2O2-induced cell damage. HE alleviated H2O2-induced loss of mitochondrial membrane potential (MMP), blocked the releases of cytochrome C and apoptosis inducing factor (AIF) from mitochondria, and thus inhibited mitochondria-mediated cell apoptosis. Furthermore, HE inhibited H2O2-induced changes of apoptosis-related proteins, such as Bcl-2, Bcl-xL, caspases -3, -9 and PARP. Further study demonstrated that the protection of HE against H2O2-induced endothelial cell damage was Nrf2-dependent. Collectively, our observations suggest that HE is capable of counteracting oxidative insults in endothelial cells, and has a potential to be a therapeutic agent against ROS-mediated vascular diseases.

Desensitizing Mitochondrial Permeability Transition by ERK-Cyclophilin D Axis Contributes to the Neuroprotective Effect of Gallic Acid against Cerebral Ischemia/Reperfusion Injury.

Ischemic stroke is a devastating disease with complex pathophysiology. Much evidence confirms that opening of the mitochondrial permeability transition pore (MPTP) is related with mitochondrial dysfunction to apoptosis in ischemic stroke, thus elucidating its signaling mechanism and screening novel MPTP inhibitor is therefore of paramount importance. Our earlier studies identified that gallic acid (GA), a naturally occurring plant phenol, endows with effect on inhibition of mitochondrial dysfunction, which has significant neuroprotective effect in cerebral ischemia/reperfusion injury. However, its molecular mechanisms regulating mitochondrial dysfunction remain elusive. Here, we uncover a role of GA in protecting mitochondria via MPTP inhibition. In addition to inhibit CypD binding to adenine nucleotide translocator, GA potentiates extracellular signal-regulated kinases (ERK) phosphorylation, leading to a decrease in cyclophilin D (CypD) expression, resulting in a desensitization to induction of MPTP, thus inhibiting caspase activation and ultimately giving rise to cellular survival. Our study firstly identifies ERK-CypD axis is one of the cornerstones of the cell death pathways following ischemic stroke, and confirms GA is a novel inhibitor of MPTP, which inhibits apoptosis depending on regulating the ERK-CypD axis.

Allicin Decreases Lipopolysaccharide-Induced Oxidative Stress and Inflammation in Human Umbilical Vein Endothelial Cells through Suppression of Mitochondrial Dysfunction and Activation of Nrf2

Background: Allicin, a major component of garlic, is regarded as a cardioprotective agent and is associated with increased endothelial function. Methods: The effects of allicin on lipopolysaccharide (LPS)-induced vascular oxidative stress and inflammation in cultured human umbilical vein endothelial cells (HUVECs) and the mechanisms underlying these effects were studied. The protective effects were measured using cell viability, a lactate dehydrogenase (LDH) assay and cell apoptosis as indicators, and the anti-oxidative activity was determined by measuring reactive oxygen species (ROS) generation, oxidative products and endogenous antioxidant enzyme activities. HUVEC mitochondrial function was assessed by determining mitochondrial membrane potential (MMP) collapse, cytochrome c production and mitochondrial ATP release. To investigate the potential underlying mechanisms, we also measured the expression of dynamic mitochondrial proteins using western blotting. Furthermore, we evaluated the Nrf2 antioxidant signaling pathway using an enzyme-linked immunosorbent assay (ELISA). Results: Our results demonstrated that allicin enhanced HUVEC proliferation, which was suppressed by LPS exposure, and LDH release. Allicin ameliorated LPS-induced apoptosis, suppressed ROS overproduction, reduced lipid peroxidation and decreased the endogenous antioxidant enzyme activities in HUVECs. These protective effects were associated with the inhibition of mitochondrial dysfunction as indicated by decreases in the MMP collapse, cytochrome c synthesis and mitochondrial ATP release. In addition, allicin attenuated the LPS-induced inflammatory responses, including endothelial cell adhesion and TNF-α and IL-8 production. Furthermore, allicin increased the expression of LXRα in a dose-dependent manner. Allicin-induced attenuation of inflammation was inhibited by LXRα siRNA treatment. Finally, allicin activated NF-E2-related factor 2 (Nrf2), which controls the defense against oxidative stress and inflammation. Conclusions: Taken together, the present data suggest that allicin attenuated the LPS-induced vascular injury process, which may be closely related to the oxidative stress and inflammatory response in HUVECs. Allicin modulated Nrf2 activation and protected the cells against LPS-induced vascular injury. Our findings suggest that allicin attenuated the LPS-induced inflammatory response in blood vessels.

Neuroprotective effects of pyrroloquinoline quinone against rotenone injury in primary cultured midbrain neurons and in a rat model of Parkinson's disease

Mitochondrial dysfunction and oxidative stress have been implicated in the pathogenesis of Parkinson's disease (PD). Pyrroloquinoline quinone (PQQ), a redox cofactor in the mitochondrial respiratory chain, has been reported to protect SH-SY5Y cells from cytotoxicity induced by rotenone, a mitochondrial complex I inhibitor. In this study, we aimed to investigate the neuroprotective effects of PQQ against rotenone injury in primary cultured midbrain neurons and in a rat model of Parkinson's disease. Pre-treatment with PQQ prevented cultured midbrain neurons from rotenone-induced apoptosis, restored mitochondrial membrane potential, inhibited intracellular reactive oxygen species (ROS) production, and affected microtubule depolymerization. On the other hand, intraperitoneal administration of PQQ exerted protective effects on rats that had received rotenone injection into the medial forebrain bundle through decreasing the apomorphine-evoked rotation, inhibiting neuronal loss and TH down-regulation in SNc, increasing the antioxidative ability, and regulating intracellular expressions of Ndufs1 and Ndufs 4. Silencing of Ndufs1 or Ndufs4 in cultured SH-SY5Y cells or midbrain neurons reduced the neuroprotective effects of PQQ. Overall, our results suggest that PQQ neuroprotection may be mediated by the inhibition of mitochondrial dysfunction and oxidative stress as well as by the gene modulation of Ndufs1 and Ndufs4.

Azilsartan, an angiotensin II type 1 receptor blocker, attenuates tert-butyl hydroperoxide-induced endothelial cell injury through inhibition of mitochondrial dysfunction and anti-inflammatory activity

Angiotensin II type 1 receptor (AT1-R) blockers protect against brain ischemia by mechanisms dependent on and independent of arterial blood pressure. However, the effects of AT1-R blockers on brain endothelial cell injury and detailed mechanisms remain unclear. The goal of this study is to investigate whether azilsartan, an AT1-R blocker, could attenuate oxidative injury in endothelial cells via regulating mitochondrial function and inflammatory responses. We found that treatment with azilsartan suppressed tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in murine brain endothelial cells (mBECs) by increasing cell viability, decreasing lactate dehydrogenase (LDH) release and inhibiting cell apoptosis. Azilsartan significantly inhibited reactive oxygen species (ROS) generation and lipid peroxidation, but had no effect on antioxidant system. We also detected preserved mitochondrial function after azilsartan treatment, as evidenced by increased mitochondrial membrane potential (MMP), reduced cytochrome c release, preserved ATP synthesis and inhibited mitochondrial swelling. In addition, azilsartan differently regulated expression of inflammatory cytokines and increased the activation of endothelial nitric oxide synthase (eNOS). Pretreatment with eNOS inhibitor L-NIO partially prevented the azilsartan-induced regulation of cytokines and protection. Furthermore, azilsartan-induced protection in our in vitro model was shown to be associated with protein stability of peroxisome proliferator-activated receptor-γ (PPAR-γ). Overall, our data suggest that the AT1-R blocker azilsartan may have therapeutic values in treating endothelial dysfunction associated neurological disorders through anti-oxidative and anti-inflammatory properties.

PBK/TOPK mediates promyelocyte proliferation via Nrf2-regulated cell cycle progression and apoptosis.

Acute myeloid leukemia (AML) is a disorder involving hematopoietic stem cells, characterized by blockage of hematopoietic cell differentiation and an increase in clonal neoplastic proliferation. AML is associated with poor patient outcome. PBK/TOPK is a protein kinase derived from PDZ-binding kinase (PBK)/T-lymphokine-activated killer (T-LAK) cell-originated protein kinase (TOPK). Previous studies have shown that PBK/TOPK is expressed in hematologic tumors. In the present study, we aimed to investigate the role of PBK/TOPK in promyelocyte proliferation and to clarify the molecular mechanism. PBK/TOPK knockdown (KD) significantly decreased cell proliferation and viability in the NB4 and HL-60 promyelocytes. PBK/TOPK KD resulted in G2/M cell cycle arrest that attributed to a decrease in cdc2 and cyclin B expression. In addition, PBK/TOPK KD caused apoptosis, as evidenced by activation of the mitochondrial apoptotic pathway and an increase in TUNEL-positive cells. PBK/TOPK KD induced mitochondrial dysfunction and ROS generation, and inhibition of mitochondrial dysfunction and ROS production suppressed PBK/TOPK KD-induced cell cycle arrest and apoptosis. Moreover, PBK/TOPK KD decreased Nrf2 expression and ARE-binding activity. Overexpression of Nrf2 inhibited the PBK/TOPK KD-induced decrease in cdc2 and cyclin B expression and cell cycle arrest, and blocked ROS production and apoptosis. Based on literature and our results, it was demonstrated that Nrf2 may be a crucial regulator that mediates PBK/TOPK-exerted promotion of cell proliferation. PBK/TOPK stabilizes Nrf2, strictly regulates the ROS level, promotes cell cycle progression and inhibits apoptosis, contributing to the proliferation of promyelocytes. Our results provide new insights into the molecular mechanism of PBK/TOPK-mediated promyelocyte proliferation and shed light on the pathogenesis of AML.

Crocin protects PC12 cells against MPP+-induced injury through inhibition of mitochondrial dysfunction and ER stress

The molecular machinery that mediates neuronal injury in neurodegenerative conditions such as Parkinson's disease (PD) remains to be fully deciphered, which will hopefully provide novel therapeutic targets for these disorders. Crocin, one of the water-soluble carotenoids isolated from the Crocus sativus L (saffron) stigma, has been reported to exert therapeutic potential in many disease models. Here, we establish an in vitro PD model using 1-methyl-4-phenylpyridinium (MPP+)-injured PC12 cells to investigate the protective effects of crocin. Crocin treatment significantly attenuated MPP+-induced cell injury and apoptosis with little toxicity, and these protective effects were still observed even if crocin treatment was delayed to 6 h after injury. Crocin also inhibited MPP+-induced mitochondrial dysfunction, as evidenced by preservation of mitochondrial membrane potential (MMP) and ATP synthesis, which correlates with suppressed endoplasmic reticulum (ER) stress through inhibiting ER chaperone and ER related apoptotic factors. In addition, ER calcium release and morphological changes in ER lumen after MPP+ exposure were all partially prevented by crocin. By using specific targeted small interfering RNA (siRNA) to knockdown the expression of the C/EBP homologous protein (CHOP), we found that crocin-induced protection and inhibition of ER stress was mediated by inverting MPP+-induced decrease of Wnt through the CHOP pathway. Our study demonstrates a pivotal role of ER stress in mediating PD related neuronal injury via the regulation of CHOP-Wnt pathway, and suggests the therapeutic values of crocin against ER stress-associated cytotoxicity.

Cardiovascular effects in vitro of a polysaccharide from Salvia miltiorrhiza.

A polysaccharide (SMP1) was isolated from the roots of Salvia miltiorrhiza. This study is designed to investigate whether SMP1 prevents H9c2 cells from hydrogen peroxide (H2O2)-induced apoptosis. The present study showed that exposure of H9c2 cells to 100mM H2O2 for 24h caused a significant increase in cell death and apoptosis, but pretreatment with SMP1 eliminated H2O2-induced apoptotic cell death. Furthermore, pretreatment with SMP1 significantly prevented the mitochondria disruption, cytochrome c release, the rise of the ratio between proapoptotic Bax and antiapoptotic Bcl-2 protein expression, and caspase-3 activation in H9c2 cells upon H2O2 stimulation. Moreover, the decline of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities together with the elevation of malondialdehyde (MDA) in PC12 cells exposed to H2O2 were remarkably reversed to normal levels by pretreatment with SMP1. These results suggest that SMP1 protects H9c2 cells from H2O2-induced apoptosis through inhibition of mitochondrial dysfunction, inactivation of caspase-3 cascade and enhancement of antioxidant capacity.

Osthole attenuates doxorubicin-induced apoptosis in PC12 cells through inhibition of mitochondrial dysfunction and ROS production.

Doxorubicin (DOX) is a potent, broad-spectrum chemotherapeutic drug used for treatment of several types of cancers. Despite its effectiveness, it has a wide range of toxic side effects, many of which most likely result from its inherent prooxidant activity. It has been reported that DOX has toxic effects on normal tissues, including brain tissue. In the current study, we investigated the protective effect of osthole isolated from Prangos ferulacea (L.) Lindl. on oxidative stress and apoptosis induced by DOX in PC12 as a neuronal model cell line. PC12 cells were pretreated with osthole 2 h after treatment with different concentrations of DOX. 24 h later, the cell viability, mitochondrial membrane potential (MMP), the activity of caspase-3, the expression ratio of Bax/Bcl-2, and the generation of intracellular ROS were detected. We found that pretreatment with osthole on PC12 cells significantly reduced the loss of cell viability, the activity of caspase-3, the increase in Bax/Bcl-2 ratio, and the generation of intracellular ROS induced by DOX. Moreover, pretreatment with osthole led to an increase in MMP in PC12 cells. In conclusion, our results indicated that pretreatment with nontoxic concentrations of osthole protected PC12 cells from DOX-mediated apoptosis by inhibition of ROS production.