PEDF Prevents Mitochondrial Function Decay and ER Stress Induced by Rotenone in Aging RPE Cells.

BACKGROUND: Neurodegenerative diseases, including age-related macular degeneration (AMD), may be linked to mitochondrial dysfunction and endoplasmic reticulum (ER) stress. We examined whether Pigment epithelium-derived factor (PEDF) could prevent changes in the structure and function of these organelles by accelerating by rotenone (ROT), a mitochondrial inhibitor, in human retinal pigment epithelium (RPE) cells of chronological age. METHODS: RPE cells from 9-20, 50-55, 60-70, and >70-year-old donors were isolated, grown as primary cultures, harvested, and treated with ROT and PEDF for electron microscope (EM), western blot analysis, and polymerase chain reaction (PCR). Reactive oxygen species (ROS) and cytoplasmic calcium [Ca2+]c and mitochondrial calcium [Ca2+]m levels were measured by flow cytometry using 2',7'-dichlorodihydrofluorescin diacetate (H2-DCF-DA), fluo-3/AM, and Rhod-2/AM, and ATP levels were measured using a luciferin/luciferase-based assay. Mitochondrial membrane potential (ΔΨm) was detected using 5,5',6,6'-tetrachloro1,1',3,3'-tetraethylbenzimid azolocarbocyanine iodide (JC-1), and susceptibility of the cells to ROT toxicity and PEDF-protective effect was determined by propidium iodide (PI) staining and lactate dehydrogenase (LDH) assay. The expression of ER stress-related genes was detected using real-time (RT)-PCR. RESULTS: We observed decay in the mitochondria of aged RPE cells, including matrix abnormalities, elongation, loss of cristae, and disruption of membrane integrity after ROT treatment. We also observed lower [Ca2+]c, higher ROS and [Ca2+]m levels, decreased ΔΨm after ROT treatment, and greater susceptibility to ROT toxicity in aged RPE cells. PEDF can protect the cristae and integrity of the mitochondrial membrane, increase ATP levels and ΔΨm, and lower ROS, [Ca2+]c, and [Ca2+]m in aged RPE cells induced by ROT. In addition, there was an increase in RDH expression in RPE cells with increasing age after PEDF treatment. Similarly, PEDF decreased the expression of ROT-induced ER stress-related genes. CONCLUSIONS: Our study provides evidence that PEDF can reduce bioenergetic deficiencies, mitochondrial decay, and ER stress in aging RPE, a condition that may trigger the onset of retinal diseases such as AMD.

Downregulation of PACAP and the PAC1 Receptor in the Basal Ganglia, Substantia Nigra and Centrally Projecting Edinger-Westphal Nucleus in the Rotenone model of Parkinson's Disease.

Numerous in vitro and in vivo models of Parkinson's disease (PD) demonstrate that pituitary adenylate cyclase-activating polypeptide (PACAP) conveys its strong neuroprotective actions mainly via its specific PAC1 receptor (PAC1R) in models of PD. We recently described the decrease in PAC1R protein content in the basal ganglia of macaques in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD that was partially reversed by levodopa therapy. In this work, we tested whether these observations occur also in the rotenone model of PD in the rat. The rotarod test revealed motor skill deterioration upon rotenone administration, which was reversed by benserazide/levodopa (B/L) treatment. The sucrose preference test suggested increased depression level while the open field test showed increased anxiety in rats rendered parkinsonian, regardless of the received B/L therapy. Reduced dopaminergic cell count in the substantia nigra pars compacta (SNpc) diminished the dopaminergic fiber density in the caudate-putamen (CPu) and decreased the peptidergic cell count in the centrally projecting Edinger-Westphal nucleus (EWcp), supporting the efficacy of rotenone treatment. RNAscope in situ hybridization revealed decreased PACAP mRNA (Adcyap1) and PAC1R mRNA (Adcyap1r1) expression in the CPu, globus pallidus, dopaminergic SNpc and peptidergic EWcp of rotenone-treated rats, but no remarkable downregulation occurred in the insular cortex. In the entopeduncular nucleus, only the Adcyap1r1 mRNA was downregulated in parkinsonian animals. B/L therapy attenuated the downregulation of Adcyap1 in the CPu only. Our current results further support the evolutionarily conserved role of the PACAP/PAC1R system in neuroprotection and its recruitment in the development/progression of neurodegenerative states such as PD.

HCH6-1, an antagonist of formyl peptide receptor-1, exerts anti-neuroinflammatory and neuroprotective effects in cellular and animal models of Parkinson's disease.

Microglial activation-induced neuroinflammation contributes to onset and progression of sporadic and hereditary Parkinson's disease (PD). Activated microglia secrete pro-inflammatory and neurotoxic IL-1ß, IL-6 and TNF-α, which subsequently promote neurodegeneration. Formyl peptide receptor-1 (FPR1) of CNS microglia functions as pattern recognition receptor and is activated by N-formylated peptides, leading to microglial activation, induction of inflammatory responses and resulting neurotoxicity. In this study, it was hypothesized that FPR1 activation of microglia causes loss of dopaminergic neurons by activating inflammasome and upregulating IL-1ß, IL-6 or TNF-α and that FPR1 antagonist HCH6-1 exerts neuroprotective effect on dopaminergic neurons. FPR1 agonist fMLF induced activation of microglia cells by causing activation of NLRP3 inflammasome and upregulation and secretion of IL-1ß, IL-6 or TNF-α. Conditioned medium (CM) of fMLF-treated microglia cells, which contains neurotoxic IL-1ß, IL-6 and TNF-α, caused apoptotic death of differentiated SH-SY5Y dopaminergic neurons by inducing mitochondrial oxidative stress and activating pro-apoptotic signaling. FPR1 antagonist HCH6-1 prevented fMLF-induced activation of inflammasome and upregulation of pro-inflammatory cytokines in microglia cells. HCH6-1 co-treatment reversed CM of fMLF-treated microglia-induced apoptotic death of dopaminergic neurons. FPR1 antagonist HCH6-1 inhibited rotenone-induced upregulation of microglial marker Iba-1 protein level, cell death of dopaminergic neurons and motor impairment in zebrafish. HCH6-1 ameliorated rotenone-induced microglial activation, upregulation of FPR1 mRNA, activation of NLRP3 inflammasome, cell death of SN dopaminergic neurons and PD motor deficit in mice. Our results suggest that FPR1 antagonist HCH6-1 possesses anti-neuroinflammatory and neuroprotective effects on dopaminergic neurons by inhibiting microglial activation and upregulation of inflammasome activity and pro-inflammatory cytokines.

Monoterpenoid Epoxidiol Ameliorates the Pathological Phenotypes of the Rotenone-Induced Parkinson's Disease Model by Alleviating Mitochondrial Dysfunction.

Parkinson's disease is the second most common neurodegenerative disease. Unfortunately, there is still no definitive disease-modifying therapy. In our work, the antiparkinsonian potential of trans-epoxide (1S,2S,3R,4S,6R)-1-methyl-4-(prop-1-en-2-yl)-7-oxabicyclo [4.1.0]heptan-2,3-diol (E-diol) was analyzed in a rotenone-induced neurotoxicity model using in vitro, in vivo and ex vivo approaches. It was conducted as part of the study of the mitoprotective properties of the compound. E-diol has been shown to have cytoprotective properties in the SH-SY5Y cell line exposed to rotenone, which is associated with its ability to prevent the loss of mitochondrial membrane potential and restore the oxygen consumption rate after inhibition of the complex I function. Under the conditions of rotenone modeling of Parkinson's disease in vivo, treatment with E-diol led to the leveling of both motor and non-motor disorders. The post-mortem analysis of brain samples from these animals demonstrated the ability of E-diol to prevent the loss of dopaminergic neurons. Moreover, that substance restored functioning of the mitochondrial respiratory chain complexes and significantly reduced the production of reactive oxygen species, preventing oxidative damage. Thus, E-diol can be considered as a new potential agent for the treatment of Parkinson's disease.

Multi-omics analysis unravels positive effect of rotenone on the cordycepin biosynthesis in submerged fermentation of Cordyceps militaris.

Cordycepin is the key pharmacologically active compound of Cordyceps militaris, and various fermentation strategies have been developed to increase cordycepin production. This study aimed to investigate the effect of rotenone on cordycepin biosynthesis in submerged fermentation of C. militaris, and also to explore its possible induction mechanisms via multi-omics analysis. Adding 5 mg/L rotenone significantly increased the cordycepin production by 316.09 %, along with mycelial growth inhibition and cell wall destruction. Moreover, transcriptomic analysis and metabolomic analysis revealed the accumulation of cordycepin was promoted by alterations in energy metabolism and amino acid metabolism pathways. Finally, the integration analysis of the two omics confirmed rotenone altered the nucleotide metabolism pathway toward adenosine and up-regulated the cordycepin synthesis genes (cns1-3) to convert adenosine to cordycepin. This work reports, for the first time, rotenone could act as an effective inducer of cordycepin synthesis.

Mitochondrial Hydrogen Peroxide Activates PTEN and Inactivates Akt Leading to Autophagy Inhibition-Dependent Cell Death in Neuronal Models of Parkinson's Disease.

Defective autophagy relates to the pathogenesis of Parkinson's disease (PD), a typical neurodegenerative disease. Our recent study has demonstrated that PD toxins (6-OHDA, MPP+, or rotenone) induce neuronal apoptosis by impeding the AMPK/Akt-mTOR signaling. Here, we show that treatment with 6-OHDA, MPP+, or rotenone triggered decreases of ATG5/LC3-II and autophagosome formation with a concomitant increase of p62 in PC12, SH-SY5Y cells, and primary neurons, suggesting inhibition of autophagy. Interestingly, overexpression of wild-type ATG5 attenuated the inhibitory effect of PD toxins on autophagy, reducing neuronal apoptosis. The effects of PD toxins on autophagy and apoptosis were found to be associated with activation of PTEN and inactivation of Akt. Overexpression of dominant negative PTEN, constitutively active Akt and/or pretreatment with rapamycin rescued the cells from PD toxins-induced downregulation of ATG5/LC3-II and upregulation of p62, as well as consequential autophagosome diminishment and apoptosis in the cells. The effects of PD toxins on autophagy and apoptosis linked to excessive intracellular and mitochondrial hydrogen peroxide (H2O2) production, as evidenced by using a H2O2-scavenging enzyme catalase, a mitochondrial superoxide indicator MitoSOX and a mitochondria-selective superoxide scavenger Mito-TEMPO. Furthermore, we observed that treatment with PD toxins reduced the protein level of Parkin in the cells. Knockdown of Parkin alleviated the effects of PD toxins on H2O2 production, PTEN/Akt activity, autophagy, and apoptosis in the cells, whereas overexpression of wild-type Parkin exacerbated these effects of PD toxins, implying the involvement of Parkin in the PD toxins-induced oxidative stress. Taken together, the results indicate that PD toxins can elicit mitochondrial H2O2, which can activate PTEN and inactivate Akt leading to autophagy inhibition-dependent neuronal apoptosis, and Parkin plays a critical role in this process. Our findings suggest that co-manipulation of the PTEN/Akt/autophagy signaling by antioxidants may be exploited for the prevention of neuronal loss in PD.

Inhibition of Complex I of the Respiratory Chain, but Not Complex III, Attenuates Degranulation and Cytokine Secretion in Human Skin Mast Cells.

The mechanisms of mast cell (MC) degranulation and MC-driven skin symptoms are well-described. In contrast, data about the role of mitochondrial respiration for immune functions of human skin MCs are lacking. Oxygen consumption rate (OCR) in primary human skin MCs during IgE-mediated activation in the absence of glucose was examined using a metabolic flux analyzer. Effects of the inhibition of mitochondrial complex I (by rotenone A) and III (by myxothiazol) on degranulation and cytokine secretion (IL-4, IL-5, IL-6, IL-13, TNF-α, and GM-CSF) were explored by the ß-hexosaminidase release assay and multiplex ELISA. IgE-mediated activation rapidly increased the mitochondrial OCR and extracellular acidification; the contribution of non-mitochondrial oxygen consumption remained unchanged at lower levels. Both myxothiazol and rotenone A reduced OCR, the mitochondrial parameters, and extracellular acidification; however, myxothiazol did not affect degranulation and cytokine secretion. In contrast, degranulation and the secretion of IL-6, IL-13, TNF-α, and GM-CSF were reduced by rotenone A, whereas the secretion of IL-4 and IL-5 was not significantly affected. The inhibitors did not affect cell viability. Our results highlight the important role played by mitochondrial respiration in primary human skin MCs and allow for a conclusion on a hierarchy of their effector functions. Drugs targeting specific pathways in mitochondria may provide future options to control MC-driven skin symptoms.

SESN2 prevents the slow-to-fast myofiber shift in denervated atrophy via AMPK/PGC-1α pathway.

BACKGROUND: Sestrin2 (SESN2), a stress-inducible protein, has been reported to protect against denervated muscle atrophy through unfolded protein response and mitophagy, while its role in myofiber type transition remains unknown. METHODS: A mouse sciatic nerve transection model was created to evaluate denervated muscle atrophy. Myofiber type transition was confirmed by western blot, fluorescence staining, ATP quantification, and metabolic enzyme activity analysis. Adeno-associated virus (AAV) was adopted to achieve SESN2 knockdown and overexpression in gastrocnemius. AMPK/PGC-1α signal was detected by western blot and activated with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR). C2C12 myotubes with rotenone treatment were adopted for in vitro experiments. RESULTS: SESN2 was found to be upregulated in denervated skeletal muscles and rotenone-treated C2C12 cells. Knockdown of SESN2 aggravated muscle atrophy and accelerated myofiber type transition from slow-twitch to fast-twitch. Moreover, AMPK/PGC-1α signaling was proven to be activated by SESN2 after denervation, which further induced the expression of hypoxia-inducible factor HIF2α. Exogenous activation of AMPK/PGC-1α signaling could counteract the addition of slow-to-fast myofiber shift caused by SESN2 knockdown and lead to the retainment of muscle mass after denervation. CONCLUSION: Collectively, the present study indicates that SESN2 prevents myofiber type transition from slow-twitch to fast-twitch and preserves muscle mass in denervated atrophy via AMPK/PGC-1α signaling. These findings contribute to a better understanding of the pathogenesis of muscle atrophy and provide novel insights into the role of SESN2 in myofiber type transition.

Redox Active α-Lipoic Acid Differentially Improves Mitochondrial Dysfunction in a Cellular Model of Alzheimer and Its Control Cells.

INTRODUCTION: Alpha lipoic acid (ALA) is a sulphur-containing organic compound, derived from octanoic acid, and an important cofactor for mitochondrial respiratory enzymes. It has strong antioxidant properties that improve mitochondrial function. We investigated if ALA improves mitochondrial dysfunction in a cellular model of Alzheimer's disease (AD). METHODS: SH-SY5Y-APP695 cells were used as a model for an early stage of AD. Vector-transfected SH-SY5Y-MOCK cells served as controls. Using these cells, we investigated mitochondrial respiration (OXPHOS), mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) production, and citrate synthase activity (CS) in cells treated with ALA. Cells were treated for 24 h with different concentrations of ALA and with or without the complex I inhibitor rotenone. RESULTS: Incubation with ALA showed a significant increase in ATP levels in both SH-SY5Y-APP695 and SH-SY5Y-MOCK cells. MMP levels were elevated in SH-SY5Y-MOCK cells, treatment with rotenone showed a reduction in MMP, which could be partly alleviated after incubation with ALA in SH-SY5Y-MOCK cells. ALA treatment showed significant differences in respiration chain complex activities in SH-SY5Y-MOCK cells. Citrate synthase activity was unaffected. ROS levels were significantly lower in both cell lines treated with ALA. CONCLUSIONS: ALA increased the activity of the different complexes of the respiratory chain, and consequently enhanced the MMP, leading to increased ATP levels indicating improved mitochondrial function. ALA only marginally protects from additional rotenone-induced mitochondrial stress.

Nootkatone alleviates rotenone-induced Parkinson's disease symptoms through activation of the PI3K/Akt signaling pathway.

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide. Nootkatone (NKT) has been shown to have neuroprotective, anti-inflammatory, and antioxidant effects and in this study, we systematically studied the efficacy and mechanism of action of NKT in rotenone (ROT)-induced PD rats. Firstly, through behavioral experiments and brain tissue staining, we found that NKT alleviated behavioral dysfunction and protected dopaminergic neurons associated with ROT-induced PD rats. Next, target prediction, protein-protein interaction (PPI), Gene Ontology (GO), and pathway enrichment analyses were used to obtain potential targets, specific biological processes, and molecular mechanisms of NKT for the potential treatment of PD. Furthermore, we also applied molecular docking to predict the binding capacity of NKT and related targets. Additionally, in vivo experiments confirmed that NKT could inhibit the expression of Mitogen-activated protein kinase 3 (MAPK3) by activating the PI3K/Akt signaling pathway, reducing neuroinflammation, and ultimately ameliorating ROT-induced PD symptoms. Taken together, the results of the study provide a clear explanation for the remission of PD symptoms by NKT, suggesting that it may be a promising candidate for the treatment of PD.

Neuroprotective effects of ATPase inhibitory factor 1 preventing mitochondrial dysfunction in Parkinson's disease.

Mitochondrial dysfunction is a key element in the progression of Parkinson's disease (PD). The inefficient operation of the electron transport chain (ETC) impairs energy production and enhances the generation of oxidative stress contributing to the loss of dopaminergic cells in the brain. ATPase inhibitory factor 1 (IF1) is a regulator of mitochondrial energy metabolism. IF1 binds directly to the F1Fo ATP synthase and prevents ATP wasting during compromised energy metabolism. In this study, we found treatment with IF1 protects mitochondria against PD-like insult in vitro. SH-SY5Y cells treated with IF1 were resistant to loss of ATP and mitochondrial inner membrane potential during challenge with rotenone, an inhibitor of complex I in the ETC. We further demonstrated that treatment with IF1 reversed rotenone-induced superoxide production in mitochondria and peroxide accumulation in whole cells. Ultimately, IF1 decreased protein levels of pro-apoptotic Bax, cleaved caspase-3, and cleaved PARP, rescuing SH-SY5Y cells from rotenone-mediated apoptotic death. Administration of IF1 significantly improved the results of pole and hanging tests performed by PD mice expressing human α-synuclein. This indicates that IF1 mitigates PD-associated motor deficit. Together, these findings suggest that IF1 exhibits a neuroprotective effect preventing mitochondrial dysfunction in PD pathology.

Stimulation of de novo glutathione synthesis by nitrofurantoin for enhanced resilience of hepatocytes.

Toxicity is not only a function of damage mechanisms, but is also determined by cellular resilience factors. Glutathione has been reported as essential element to counteract negative influences. The present work hence pursued the question how intracellular glutathione can be elevated transiently to render cells more resistant toward harmful conditions. The antibiotic nitrofurantoin (NFT) was identified to stimulate de novo synthesis of glutathione in the human hepatoma cell line, HepG2, and in primary human hepatocytes. In intact cells, activation of NFT yielded a radical anion, which subsequently initiated nuclear-factor-erythroid 2-related-factor-2 (Nrf2)-dependent induction of glutamate cysteine ligase (GCL). Application of siRNA-based intervention approaches confirmed the involvement of the Nrf2-GCL axis in the observed elevation of intracellular glutathione levels. Quantitative activation of Nrf2 by NFT, and the subsequent rise in glutathione, were similar as observed with the potent experimental Nrf2 activator diethyl maleate. The elevation of glutathione levels, observed even 48 h after withdrawal of NFT, rendered cells resistant to different stressors such as the mitochondrial inhibitor rotenone, the redox cycler paraquat, the proteasome inhibitors MG-132 or bortezomib, or high concentrations of NFT. Repurpose of the antibiotic NFT as activator of Nrf2 could thus be a promising strategy for a transient and targeted activation of the endogenous antioxidant machinery. Graphical abstract.

Does the Operation of Mitochondrial ATP-Dependent Potassium Channels Affect the Structural Component of Mitochondrial and Endothelial Dysfunctions in Experimental Parkinsonism?

We have previously demonstrated that the development of oxidative stress in some pathologies can be prevented by activation of the mitochondrial ATP-dependent potassium channel (mitoKATP). Here we studied the effect of modulation of mitoKATP on the development of mitochondrial and endothelial dysfunction in the medulla oblongata and myocardium of rats with experimental parkinsonism. It is known that uridine-5'-diphosphate, activator of mitoKATP, does not penetrate the plasma membrane, but it can be synthesized in cells from exogenous uridine that is delivered into cells by special transport systems. Our results suggest that mitoKATP is involved in the development of mitochondrial and endothelial dysfunction in experimental parkinsonism and prove the cardio- and neuroprotective effects of uridine.

Discovery of novel anti-breast cancer agents derived from deguelin as inhibitors of heat shock protein 90 (HSP90).

A series of O-substituted analogues of the B,C-ring truncated scaffold of deguelin were designed as C-terminal inhibitors of heat shock protein 90 (HSP90) and investigated as novel antiproliferative agents against HER2-positive breast cancer. Among the synthesized compounds, compound 80 exhibited significant inhibition in both trastuzumab-sensitive and trastuzumab-resistant breast cancer cells, whereas compound 80 did not show any cytotoxicity in normal cells. Compound 80 markedly downregulated the expression of the major client proteins of HSP90 in both cell types, indicating that the cytotoxicity of 80 in breast cancer cells is attributed to the destabilization and inactivation of HSP90 client proteins and that HSP90 inhibition represents a promising strategy to overcome trastuzumab resistance. A molecular docking study of 80 with the homology model of a HSP90 homodimer showed that 80 fit nicely in the C-terminal domain with a higher electrostatic complementary score than that of ATP.

Neuroprotection of Rotenone-Induced Parkinsonism by Ursolic Acid in PD Mouse Model.

BACKGROUND: Parkinson's Disease (PD) is characterized by both motor and non-motor symptoms. The presynaptic neuronal protein, α-Synuclein, plays a pivotal role in PD pathogenesis and is associated with both genetic and sporadic origin of the disease. Ursolic Acid (UA) is a well-known bioactive compound found in various medicinal plants, widely studied for its anti-inflammatory and antioxidant activities. OBJECTIVE: In this research article, the neuroprotective potential of UA has been further explored in the Rotenone-induced mouse model of PD. METHODS: To investigate our hypothesis, we have divided mice into 4 different groups, control, drug only control, Rotenone-intoxicated group, and Rotenone-intoxicated mice treated with UA. After the completion of dosing, behavioral parameters were estimated. Then mice from each group were sacrificed and the brains were isolated. Further, the biochemical tests were assayed to check the balance between the oxidative stress and endogenous anti-oxidants; and TH (Tyrosine Hydroxylase), α-Synuclein, Akt (Serine-threonine protein kinase), ERK (Extracellular signal-regulated kinase) and inflammatory parameters like Nuclear Factor-κB (NF-κB) and Tumor Necrosis Factor- α (TNF-α) were assessed using Immunohistochemistry (IHC). Western blotting was also done to check the expressions of TH and α-Synuclein. Moreover, the expression levels of PD related genes like α-Synuclein, ß-Synuclein, Interleukin-1ß (IL-1ß), and Interleukin-10 (IL-10) were assessed by using Real-time PCR. RESULTS: The results obtained in our study suggested that UA significantly reduced the overexpression of α-Synuclein and regulated the phosphorylation of survival-related kinases (Akt and ERK) apart from alleviating the behavioral abnormalities and protecting the dopaminergic neurons from oxidative stress and neuroinflammation. CONCLUSION: Thus, our study shows the neuroprotective potential of UA, which can further be explored for possible clinical intervention.

Molecular interaction studies of Deguelin and its derivatives with Cyclin D1 and Cyclin E in cancer cell signaling pathway: The computational approach.

Deguelin is a major active ingredient and principal component in several plants and it is a potential molecule to target proteins of cancer cell signaling pathway. As a complex natural extract, deguelin interacts with various molecular targets to exert its anti-tumor properties at nanomolar level. It induces cell apoptosis by blocking anti-apoptotic pathways, while inhibiting tumor cell multiplication and malignant transformation through p27-cyclin-E-pRb-E2F1- cell cycle control and HIF-1alphaVEGF antiangiogenic pathways. In silico studies of deguelin and its derivatives is performed to explore interactions with Cyclin D1 and Cyclin E to understand the molecular insights of derivatives with the receptors. Deguelin and its derivatives are minimized by Avogadro to achieve stable conformation. All docking simulation are performed with AutoDockVina and virtual screening of docked ligands are carried out based on binding energy and number of hydrogen bonds. Molecular dynamics (MD) and Simulation of Cyclin D1 and Cyclin E1 is performed for 100 ns and stable conformation is obtained at 78 ns and 19 ns respectively. Ligands thus obtained from docking studies may be probable target to inhibit cancer cell signaling pathways.

Aerobic respiration: proof of concept for the oxygen-centric murburn perspective.

The inner mitochondrial membrane protein complexes (I-V) and prokaryotic respiratory machinery are examined for a deeper understanding of their structure-function correlations and dynamics. In silico analysis of the structure of complexes I-IV, docking studies and erstwhile literature confirm that they carry sites which are in close proximity to DROS (diffusible reactive oxygen species) generating redox centers. These findings provide supportive evidence for the newly proposed oxygen-centric chemical-coupling mechanism (murburn concept), wherein DROS catalyzes the esterification of inorganic phosphate to ADP. Further, in a reductionist system, we demonstrate that a DROS (like superoxide) can effectively esterify inorganic phosphate to ADP. The impact of these findings and the interactive dynamics of classical inhibitors (rotenone and cyanide), uncouplers (dinitrophenol and uncoupling protein) and other toxins (atractyloside and oligomycin) are briefly discussed. Highlights • Earlier perception: Complexes (I-IV) pump protons and Complex V make ATP (aided by protons) • Herein: Respiratory molecular machinery is probed for new structure-function correlations • Analyses: Quantitative arguments discount proton-centric ATP synthesis in mitochondria and bacteria • In silico data: ADP-binding sites and O2/ diffusible reactive oxygen species (DROS)-accessible channels are unveiled in respiratory proteins • In vitro data: Using luminometry, ATP synthesis is demonstrated from ADP, Pi and superoxide • Inference: Findings agree with decentralized ADP-Pi activation via oxygen-centric murburn scheme Communicated by Ramaswamy H. Sarma.

Rotenone Attenuates Renal Injury in Aldosterone-Infused Rats by Inhibiting Oxidative Stress, Mitochondrial Dysfunction, and Inflammasome Activation.

BACKGROUND: Reactive oxygen species (ROS) and inflammation both contribute to the progression of aldosterone-induced renal injury. To better understand the underlying mechanisms, we examined mitochondrial dysfunction and NLRP3 inflammasome activation in aldosterone-infused rats, and explored the role of rotenone in attenuating these injuries. MATERIAL AND METHODS: Sprague-Dawley rats were divided into 3 groups: vehicle-treated, aldosterone-infused, and aldosterone plus rotenone. Renal damage was evaluated using PAS staining and electron microscopy. Levels of ROS were measured from renal tissue and serum; immunohistochemistry analysis examined the inflammation pathway; Western blot and real-time PCR assessed NLRP3 inflammasome activity. RESULTS: Glomerular segmental sclerosis, foot process effacement, and proteinuria were demonstrated in the aldosterone-infused rats. Specifically, the thiobarbituric acid-reactive substances (TBARS) oxidative stress marker, MDA, was significantly increased; ATP content and mtDNA copy number were markedly decreased; inflammatory mediators NF-κB p65 and CTGF were upregulated; and NLRP3 inflammasome and its related target proteins, IL-1ß and IL-18, were also increased. Treatment with rotenone, an inhibitor of mitochondrial complex I, significantly attenuated oxidative stress, mitochondrial dysfunction, and inflammasome response in aldosterone-infused rats. CONCLUSIONS: Rotenone ameliorated aldosterone-infused renal injury, possibly by inhibiting oxidative stress, mitochondrial dysfunction, and NLRP3 inflammasome activity. These results provide novel evidence for the role of rotenone in aldosterone-induced renal injury or other chronic kidney disease.

Rotenone affects p53 transcriptional activity and apoptosis via targeting SIRT1 and H3K9 acetylation in SH-SY5Y cells.

The protein deacetylase SIRT1 has been recognized to exert its protective effect by directly deacetylasing histone and many other transcriptional factors including p53. However, the effect of SIRT1 on p53 expression at the transcriptional level still remains to be elucidated. In this study, we found that rotenone treatment decreased cell viability, induced apoptosis, reduced SIRT1 level, and promoted p53 expression. Pre-treatment with resveratrol, a SIRT1 activator, could attenuate rotenone-induced cell injury and p53 expression, whereas down-regulation of SIRT1 directly increased p53 expression. Moreover, chromatin immunoprecipitation experiments showed that SIRT1 bound to H3K9 within the p53 promoter region, and this binding resulted in decreased H3K9 acetylation and increased H3K9 tri-methylation, thereby inhibiting p53 gene transcription. In conclusion, our data indicate that rotenone promotes p53 transcription and apoptosis through targeting SIRT1 and H3K9. This leads to nigrostriatal degeneration, the main pathogenic mechanism of motor features of Parkinson's disease. SIRT1, a deacetylase enzyme, has neuroprotective effects for Parkinson's disease via targeting various factors. Resveratrol activated SIRT1 can target H3K9 and regulate p53 gene expression at the transcriptional level, thus inhibiting p53 transcription to enhance neuroprotection, alleviating rotenone induced dopaminergic neurodegeneration. We think these findings should provide a new strategy for the treatment of Parkinson's disease.

Saffloflavonesides A and B, two rearranged derivatives of flavonoid C-glycosides with a furan-tetrahydrofuran ring from Carthamus tinctorius.

Two new rearranged derivatives of flavonoid C-glycosides, saffloflavonesides A (1) and B (2), were isolated from the florets of Carthamus tinctorius. Their structures were determined using UV, IR, HRESIMS, and 1D and 2D NMR data and by comparing experimental and calculated electronic circular dichroism (ECD) spectra. Compounds 1 and 2 were unprecedented chalcone and flavanone derivatives possessing a furan conjoining tetrahydrofuran ring. A potential biosynthetic pathway was proposed. At 10 µM, 1 and 2 both showed strong inhibitory activity against PC12 cell damage induced by rotenone.