Bax regulates production of superoxide in both apoptotic and nonapoptotic neurons: role of caspases

Optimal strategies of oncolytic virus-bortezomib therapy via the apoptotic, necroptotic, and oncolysis signaling network

Bortezomib and oncolytic virotherapy are two emerging targeted cancer therapies. Bortezomib, a proteasome inhibitor, disrupts protein degradation in cells, leading to the accumulation of unfolded proteins that induce apoptosis. On the other hand, virotherapy uses genetically modified oncolytic viruses (OVs) to infect cancer cells, trigger cell lysis, and activate anti-tumor response. Despite progress in cancer treatment, identifying administration protocols for therapeutic agents remains a significant concern, aiming to strike a balance between efficacy, minimizing toxicity, and administrative costs. In this work, optimal control theory was employed to design a cost-effective and efficient co-administration protocols for bortezomib and OVs that could significantly diminish the population of cancer cells via the cell death program with the NF$ \kappa $B-BAX-RIP1 signaling network. Both linear and quadratic control strategies were explored to obtain practical treatment approaches by adapting necroptosis protocols to efficient cell death programs. Our findings demonstrated that a combination therapy commencing with the administration of OVs followed by bortezomib infusions yields an effective tumor-killing outcome. These results could provide valuable guidance for the development of clinical administration protocols in cancer treatment.

The intrinsic apoptotic pathway lies upstream of reactive species production in cortical neurons and age-related oxidative stress in the brain

A BAX- and mitochondria-dependent production of reactive oxygen species (ROS) and reactive species (reactive nitrogen species, RNS) lying downstream of these ROS occurs in apoptotic and nonapoptotic mouse sympathetic neurons and cerebellar granule cells in cell culture. These ROS have been shown to lie downstream of caspase 3 in mouse sympathetic neurons. Here we show that BAX is necessary for similar ROS production in apoptotic and nonapoptotic mouse cortical neurons in cell culture and that it also positively regulates oxidative stress in the brains of mice of different ages. Brains from mice with genetically reduced levels of mitochondrial superoxide dismutase 2 (SOD2) exhibited elevated levels of DNA strand breaks consistent with oxidative damage. Lipid peroxides were also elevated at some ages in comparison to the brains of wild type animals. BAX deletion in these mice reduced both brain DNA strand breaks and lipid peroxide levels to well below those of wild type animals. Deletion of caspase 3 greatly reduced age-augmented levels of brain oxidative stress markers including lipid peroxides, oxidized DNA, and nitrosylated proteins. These findings indicate that BAX contributes to ROS production in mouse cortical neurons, to oxidative stress their brains, and that this effect is likely mediated via caspase 3 activity.

Induction of G0/G1 phase cell cycle arrest and apoptosis by thymol through ROS generation and caspase-9/-3 activation in breast and colorectal cancer cell lines

BACKGROUND

Cancer is a major malignancy and one of the leading causes of death; it calls for a proactive strategy for the cure. Herbs are reservoirs of novel chemical entities and their phytochemical exploration has contributed considerably to the discovery of new anticancer drugs. Thymol, a natural phenolic monoterpenoid, has been implicated with many medicinal properties, including anticancer ones. However, the anti-proliferative and apoptosis-inducing ability of thymol on MDA-MB-231 and HCT-8 cell lines has not been studied yet in detail, and hence this study was conceived.

MATERIALS AND METHODS

We studied the cytotoxicity, morphological alterations of the cell, oxidative stress, cell cycle modulation, apoptosis and expression of apoptosis-related proteins that ensued due to thymol treatment in these cancer cells.

RESULTS

Thymol inhibited the cell proliferation, altered the morphology of the cells, increased the intracellular ROS level, arrested the cells in G0/G1 phase, induced apoptosis, upregulated pro-apoptotic protein p53 expression, downregulated anti-apoptotic protein Bcl-xL expression, and activated caspase-9 and -3.

CONCLUSION

These findings elucidate that thymol induces apoptosis through the intrinsic pathway, in MDA-MB-231 breast and HCT-8 colorectal cancer cells through ROS generation and G0/G1 phase cell cycle arrest. This reiterates the broad-spectrum anti-tumor potential of thymol and provides an insight to study further to be developed into an anticancer drug.

Bax Contributes to Retinal Ganglion Cell Dendritic Degeneration During Glaucoma

The BCL-2 (B-cell lymphoma-2) family of proteins contributes to mitochondrial-based apoptosis in models of neurodegeneration, including glaucomatous optic neuropathy (glaucoma), which degrades the retinal ganglion cell (RGC) axonal projection to the visual brain. Glaucoma is commonly associated with increased sensitivity to intraocular pressure (IOP) and involves a proximal program that leads to RGC dendritic pruning and a distal program that underlies axonopathy in the optic projection. While genetic deletion of the Bcl2-associated X protein (Bax^-/-) prolongs RGC body survival in models of glaucoma and optic nerve trauma, axonopathy persists, thus raising the question of whether dendrites and the RGC light response are protected. Here, we used an inducible model of glaucoma in Bax^-/- mice to determine if Bax contributes to RGC dendritic degeneration. We performed whole-cell recordings and dye filling in RGCs signaling light onset (αON-Sustained) and offset (αOFF-Sustained). We recovered RGC dendritic morphologies by confocal microscopy and analyzed dendritic arbor complexity and size. Additionally, we assessed RGC axon function by measuring anterograde axon transport of cholera toxin subunit B to the superior colliculus and behavioral spatial frequency threshold (i.e., spatial acuity). We found 1 month of IOP elevation did not cause significant RGC death in either WT or Bax^-/- retinas. However, IOP elevation reduced dendritic arbor complexity of WT αON-Sustained and αOFF-Sustained RGCs. In the absence of Bax, αON- and αOFF-Sustained RGC dendritic arbors remained intact following IOP elevation. In addition to dendrites, neuroprotection by Bax^-/- generalized to αON-and αOFF-Sustained RGC light- and current-evoked responses. Both anterograde axon transport and spatial acuity declined during IOP elevation in WT and Bax^-/- mice. Collectively, our results indicate Bax contributes to RGC dendritic degeneration and distinguishes the proximal and distal neurodegenerative programs involved during the progression of glaucoma.

NGF-Dependent and BDNF-Dependent DRG Sensory Neurons Deploy Distinct Degenerative Signaling Mechanisms

The nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are trophic factors required by distinct population of sensory neurons during development of the nervous system. Neurons that fail to receive appropriate trophic support are lost during this period of naturally occurring cell death. In the last decade, our understanding of the signaling pathways regulating neuronal death following NGF deprivation has advanced substantially. However, the signaling mechanisms promoting BDNF deprivation-induced sensory neuron degeneration are largely unknown. Using a well-established in vitro culture model of dorsal root ganglion (DRG), we have examined degeneration mechanisms triggered on BDNF withdrawal in sensory neurons. Our results indicate differences and similarities between the molecular signaling pathways behind NGF and BDNF deprivation-induced death. For instance, we observed that the inhibition of Trk receptors (K252a), PKC (Gö6976), protein translation (cycloheximide; CHX), or caspases (zVAD-fmk) provides protection from NGF deprivation-induced death but not from degeneration evoked by BDNF-withdrawal. Interestingly, degeneration of BDNF-dependent sensory neurons requires BAX and appears to rely on reactive oxygen species (ROS) generation rather than caspases to induce degeneration. These results highlight the complexity and divergence of mechanisms regulating developmental sensory neuron death.

Membrane Depolarization Inhibits BIMEL Upregulation but Prevents Neuronal Apoptosis Primarily by Increasing Cellular GSH Levels

Sympathetic neurons deprived of nerve growth factor (NGF) die by apoptosis. Chronic depolarization with elevated concentrations of extracellular potassium ([K⁺]_E) supports long-term survival of these and other types of neurons in culture. While depolarization has long been used to support neuronal cultures, little is known about the mechanism. We explored how chronic depolarization of NGF-deprived mouse sympathetic neurons in culture blocks apoptotic death. First, we determined the effects of elevated [K⁺]_E on proapoptotic BH3-only proteins reported to be upregulated in sympathetic neurons after NGF withdrawal. Upregulation of BIM_EL was blocked by depolarization while upregulation of PUMA was not. BMF levels did not increase after NGF withdrawal, and elevated [K⁺]_E had no effect on its expression. dp5/HRK was not detectable. A large increase in production of mitochondria-derived reactive species (RS), including reactive oxygen species (ROS), occurs in NGF-deprived sympathetic neurons. Suppressing these RS prevents cytochrome c release from mitochondria and apoptosis. The addition of high [K⁺]_E to cultures rapidly blocked increased RS and cytochrome c release. Elevated [K⁺]_E caused an increase of the cellular antioxidant glutathione (GSH). Preventing this increase prevented the elevated [K⁺]_E from blocking cytochrome c release and death. While suppression of BIM_EL upregulation by elevated [K⁺]_E may contribute to high [K⁺]_E pro-survival effects, we conclude that elevated [K⁺]_E prevents apoptotic death of NGF-deprived sympathetic neurons primarily via an antioxidant mechanism.

The intrinsic apoptotic pathway lies upstream of oxidative stress in multiple organs

Oxidative stress increases with age in multiple organ systems and is implicated in the development of age-related pathologies in them. Studies from our laboratory show that the intrinsic pathway proapoptotic proteins BAX and caspase-3 (CASP3) lie upstream of mitochondrial production of oxidative stress-inducing reactive species (RS) such as reactive oxygen and reactive nitrogen species (ROS and RNS) in apoptotic and nonapoptotic neurons in cell culture. Our objective in this study was to determine if these findings could be generalized to the development of oxidative stress in nonneuronal tissues in vivo. We first investigated the effect of genetic deletion of Bax on DNA damage in the liver, heart and kidneys of female mice of increasing ages (5, 14, 22 months). The organs of the aged mice showed increased oxidative DNA strand breaks compared to young animals (5 month). Ablation of Bax greatly reduced this damage. We next assessed lipid peroxidation, DNA oxidation, and protein tyrosine nitration to determine whether Casp3 deletion reduces oxidative stress in the hearts, livers, and kidneys of 12-month-old female mice. Lipid peroxides and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were much lower in organs from mice with depleted Casp3 than in those of wild type animals. Nitration of protein tyrosine residues, caused by RNS, was also significantly suppressed in the tissues of Casp3 null mice compared to those in wild type mice. Our findings indicate that BAX and CASP3 have a vital role in the generation of oxidative stress in organs of aged mice.

Loss of AKAP1 triggers Drp1 dephosphorylation-mediated mitochondrial fission and loss in retinal ganglion cells

Impairment of mitochondrial structure and function is strongly linked to glaucoma pathogenesis. Despite the widely appreciated disease relevance of mitochondrial dysfunction and loss, the molecular mechanisms underlying mitochondrial fragmentation and metabolic stress in glaucoma are poorly understood. We demonstrate here that glaucomatous retinal ganglion cells (RGCs) show loss of A-kinase anchoring protein 1 (AKAP1), activation of calcineurin (CaN) and reduction of dynamin-related protein 1 (Drp1) phosphorylation at serine 637 (Ser637). These findings suggest that AKAP1-mediated phosphorylation of Drp1 at Ser637 has a critical role in RGC survival in glaucomatous neurodegeneration. Male mice lacking AKAP1 show increases in CaN and total Drp1 levels, as well as a decrease in Drp1 phosphorylation at Ser637 in the retina. Ultrastructural analysis of mitochondria shows that loss of AKAP1 triggers mitochondrial fragmentation and loss, as well as mitophagosome formation in RGCs. Loss of AKAP1 deregulates oxidative phosphorylation (OXPHOS) complexes (Cxs) by increasing CxII and decreasing CxIII-V, leading to metabolic and oxidative stress. Also, loss of AKAP1 decreases Akt phosphorylation at Serine 473 (Ser473) and threonine 308 (Thr308) and activates the Bim/Bax signaling pathway in the retina. These results suggest that loss of AKAP1 has a critical role in RGC dysfunction by decreasing Drp1 phosphorylation at Ser637, deregulating OXPHOS, decreasing Akt phosphorylation at Ser473 and Thr308, and activating the Bim/Bax pathway in glaucomatous neurodegeneration. Thus, we propose that overexpression of AKAP1 or modulation of Drp1 phosphorylation at Ser637 are potential therapeutic strategies for neuroprotective intervention in glaucoma and other mitochondria-related optic neuropathies.

Noncanonical Cell Fate Regulation by Bcl-2 Proteins

Bcl-2 proteins are widely known as key controllers of mitochondrial outer membrane permeabilization, arguably the most important step of intrinsic apoptosis. Accumulating evidence indicate that most, if not all, members of the Bcl-2 protein family also mediate a number of apoptosis-unrelated functions. Intriguingly, many of these functions ultimately impinge on cell fate decisions via apoptosis-dependent or -independent mechanisms, delineating a complex network through which Bcl-2 family members regulate cell survival and death. Here, we critically discuss the mechanisms through which Bcl-2 proteins influence cell fate as they regulate autophagy, cellular senescence, inflammation, bioenergetic metabolism, Ca²⁺ fluxes, and redox homeostasis.

The Anti-Inflammatory Effect of Feiyangchangweiyan Capsule and Its Main Components on Pelvic Inflammatory Disease in Rats via the Regulation of the NF-κB and BAX/BCL-2 Pathway

Although gastroenteritis and pelvic inflammatory disease (PID) occur in the gastrointestinal tract and pelvis, respectively, they display similar pathogeneses. The incidence of inflammation in these conditions is usually associated with dysbacteriosis, and, at times, they are caused by the same pathogenic bacteria, Escherichia coli and Streptococcus aureus. Feiyangchangweiyan capsule (FYC) is a traditional Chinese patent medicine that is widely used to treat bacterial dysentery and acute and chronic gastroenteritis. However, whether it has an effect on PID is unclear. The aim of this study was to investigate the anti-inflammatory effect of FYC and its main components, gallic acid (GA), ellagic acid (EA), and syringin (SY), on a pathogen-induced PID model and illustrate their potential mechanism of action. Female specific pathogen-free SD rats (n = 1110) were randomly divided into control, PID, FYC, GA, EA, SY, GA + EA, GA + SY, EA + SY, GA + EA + SY, and Fuke Qianjin capsule (FKC) positive groups. Histological examination and enzyme-linked immunosorbent assay (ELISA) were carried out as well as western blot analysis to detect the expression of NF-κB, BAX, BCL-2, and JNK. In this study, FYC and its main components dramatically suppressed the infiltration of inflammatory cells, reduced the production of IL-1β, TNF-α, and MCP-1, and elevated the IL-10 level to varying degrees. We also found that FYC and its main components inhibited the expression of BAX induced by infection and increased the expression of Bcl-2. FYC, GA, EA, and SY could also block the activation of the NF-κB pathway. Finally, we found that the phosphorylation of JNK could be decreased by FYC, GA, and SY. FYC and its main components exhibit anti-inflammatory effect on a pathogen-induced PID model by regulating the NF-κB and apoptosis signaling pathways.

Alcohol Dehydrogenase 1B Suppresses β-Amyloid-Induced Neuron Apoptosis

β-amyloid (Aβ) deposition, neurofibrillary tangles induced by phosphorylation of tau protein, and neuronal apoptosis are pathological hallmarks of Alzheimer’s disease (AD). The dementia rate in alcoholic abusers were found to be higher than in control people. The present study explored the potential roles of alcohol dehydrogenase 1B (ADH1B) in AD pathology by determining the ADH1B levels in AD patient sera, in the hippocampus of APP/PS-1 AD model mice, and in an AD model cell line treated with Aβ1-42. The results show that ADH1B levels decreased significantly both in the serum of AD patients and in the hippocampus of APP/PS-1 AD model mice. In addition, the apoptotic rate was reduced and viability was significantly increased in AD model cells transfected with ADH1B overexpression vector. The levels of the p75 neurotrophin receptor (p75NTR), an Aβ1-42 receptor, were down-regulated in the ADH1B overexpressing AD model cell and up-regulated in cells transfected with the shRNA vector of ADH1B. Protein levels of cleaved caspase-3 and Bax decreased significantly, whereas Bcl-2 levels increased in cells overexpressing ADH1B. The opposite trend was observed for cleaved caspase-3, Bax, and Bcl-2 levels in cells transfected with the shRNA vector of ADH1B. The levels of reactive oxygen species (ROS) were found to be reduced in ADH1B overexpressing cells and increased when cells were transfected with the shRNA vector of ADH1B. These results indicate that ADH1B might be important in the prevention of AD, especially for abusers of alcohol, and a potential new target of AD treatment.

Synergistic Effects of Bortezomib-OV Therapy and Anti-Invasive Strategies in Glioblastoma: A Mathematical Model

It is well-known that the tumor microenvironment (TME) plays an important role in the regulation of tumor growth and the efficacy of anti-tumor therapies. Recent studies have demonstrated the potential of combination therapies, using oncolytic viruses (OVs) in conjunction with proteosome inhibitors for the treatment of glioblastoma, but the role of the TME in such therapies has not been studied. In this paper, we develop a mathematical model for combination therapies based on the proteosome inhibitor bortezomib and the oncolytic herpes simplex virus (oHSV), with the goal of understanding their roles in bortezomib-induced endoplasmic reticulum (ER) stress, and how the balance between apoptosis and necroptosis is affected by the treatment protocol. We show that the TME plays a significant role in anti-tumor efficacy in OV combination therapy, and illustrate the effect of different spatial patterns of OV injection. The results illustrate a possible phenotypic switch within tumor populations in a given microenvironment, and suggest new anti-invasion therapies.

Protective effect of 5-HT7 receptor activation against glutamate-induced neurotoxicity in human neuroblastoma SH-SY5Y cells via antioxidative and antiapoptotic pathways

Serotonin exerts anti-inflammatory, antioxidant and antiapoptotic effects through 5-HT7 receptors. The present study determined the role of 5-HT7 receptors in glutamate-induced neurotoxicity by using human SH-SY5Y neuroblastoma cells. The cells were pretreated with different concentrations of 5-HT7 receptor agonist LP44 and antagonist SB269970 for 60 min, followed by treatment with glutamate. Cell proliferation was measured using xCELLigence system. Treatment with all the concentrations of LP44 significantly protected the cells from the toxic effects of glutamate after 24, 48 and 72 h. Although 5-HT7 receptor expression was significantly upregulated in glutamate-treated cells, it was downregulated in LP44-pretreated cells. Furthermore, LP44 treatment significantly decreased malondialdehyde levels and increased superoxide dismutase activities and glutathione levels. Moreover, LP44 treatment significantly decreased tumor necrosis factor alpha (TNF-α) levels and inhibited caspase 3 and caspase 9 mRNA expression. In contrast, SB269970 treatment exerted an insignificant effect on oxidative stress, inflammation and apoptosis. These findings suggest that exogenous stimulation of the 5-HT7 receptors may be protective in glutamate-induced neurotoxicity and that 5-HT7 receptor agonists can be used as therapeutic agents for preventing glutamate-induced neurological disorders.

Structural characterization and anti-inflammatory potency of Mesobuthus martensii Karsch oligopeptides in lipopolysaccharide (LPS)-induced RAW264.7 macrophages

Scorpion venom represents a significant source of bio-active peptides. However, the anti-inflammatory potency of scorpion venom oligopeptides (CMOs) has not been well explored. In the current study, thirty-five CMOs were isolated, the amino acid sequences were identified, and the anti-inflammatory potency was further explored in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. The results showed that CMO-1 (His-Tyr-Gly-His) demonstrated the best anti-inflammatory potency by attenuating inflammatory cytokine (NO, TNF-α, IL-6, and IL-1β) production. CMO-1 also inhibited IκBα degradation and p65 nuclear translocation and suppressed NF-κB activation. Moreover, CMO-1 inhibited the phosphorylation of ERK, JNK, and p38 MAPKs. It is worth noting that CMO-1 exhibited anti-inflammatory potency; thus, it is a potential anti-inflammatory agent.

Scorpion venom represents a significant source of bio-active peptides.

Beneficial Impact and Molecular Mechanism of Bacillus coagulans on Piglets' Intestine

The aim of this research was to investigate the beneficial impact and molecular mechanism of B. coagulans on piglets' intestine. Twenty-four 21 days old weaned piglets were allotted to three treatments: Control group (basal diet), B6 group (basal diet + 2 × 10⁶ CFU/g B. coagulans), and the B7 group (basal diet + 2 × 10⁷ CFU/g B. coagulans). The results showed that, compared with the control group, the B7 group had a reduced cholesterol content and gamma glutamyl transpeptidase (GGT) in plasma (p < 0.05); the B6 and B7 groups had a significantly decreased diarrhea rate and diamine oxidase (DAO) activity in plasma (p < 0.05), increased villus height in ileum and decreased crypt depth in the jejunum (p < 0.05); increased activities of superoxide dismutase (SOD) and catalase (CAT), and decreased the content of malondialdehyde (MDA) and H₂O₂ in the intestine (p < 0.05). These data suggested that supplementing B. coagulans had beneficial impacts on promoting nutrients' metabolism, maintaining intestinal integrity, and alleviating oxidative stress and diarrhea. Further research of molecular mechanisms showed changing expression levels of related proteins and genes, suggesting that these could be involved in the regulation of the impact. The community composition of the gut microbiota was also found to be altered in several operational taxonomic units within the genus, Prevotella (order Bacteroidales), and the order, Clostridiales.

N-Adamantyl-4-Methylthiazol-2-Amine Attenuates Glutamate-Induced Oxidative Stress and Inflammation in the Brain

In this study, we explored the possible mechanisms underlying the neuroprotective and anti-oxidative effects of N-adamantyl-4-methylthiazol-2-amine (KHG26693) against in vivo glutamate-induced toxicity in the rat cerebral cortex. Our results showed that pretreatment with KHG26693 significantly attenuated glutamate-induced elevation of lipid peroxidation, tumor necrosis factor-α, interferon gamma, IFN-γ, interleukin-1β, nitric oxide, reactive oxygen species, NADPH oxidase, caspase-3, calpain activity, and Bax. Furthermore, KHG26693 pretreatment attenuated key antioxidant parameters such as levels of superoxide dismutase, catalase, glutathione, and glutathione reductase. KHG26693 also attenuated the protein levels of inducible nitric oxide synthase, neuronal nitric oxide synthase, nuclear factor erythroid 2-related factor 2, heme oxygenase-1, and glutamate cysteine ligase catalytic subunit caused by glutamate toxicity. Finally, KHG26693 mitigated glutamate-induced changes in mitochondrial ATP level and cytochrome oxidase c. Thus, KHG26693 functions as neuroprotective and anti-oxidative agent against glutamate-induced toxicity through its antioxidant and anti-inflammatory activities in rat brain at least in part.

Dissociation of JNK Activation from Elevated Levels of Reactive Oxygen Species, Cytochrome c Release, and Cell Death in NGF-Deprived Sympathetic Neurons

Withdrawal of nerve growth factor (NGF) from sympathetic neurons causes their apoptotic death. Activation of c-Jun NH2-terminal kinase (JNK) may contribute to this death by the induction and phosphorylation of pro-apoptotic Bcl-2 proteins, such as Bax, that are involved in cytochrome c release from mitochondria and reactive oxygen species (ROS) production. Induction of either JNK or ROS may stimulate the other, and both may regulate release of apoptogenic factors from the mitochondria. In order to discern the relationship between JNK and ROS in apoptosis, we treated NGF-deprived, mouse sympathetic neurons with a JNK inhibitor and examined the effect on several important apoptotic events. Block of JNK activation prevented induction of c-Jun expression and resulted in a dose-dependent, yet surprisingly modest, increase in cell survival after 48 h of NGF deprivation. JNK suppression was also not sufficient to prevent the elevation in ROS or the release of cytochrome c from the mitochondria in NGF-deprived sympathetic neurons. Bax deletion prevents apoptotic death of NGF-deprived neurons by preventing release of cytochrome c from their mitochondria. It also prevents increased ROS on NGF deprivation. However, we found that induction of c-Jun in cells lacking Bax was equivalent to that in wild-type neurons. Our results suggest that while JNK activation plays an important role in many forms of apoptosis, it may not be a crucial regulator of Bax-dependent events involved in the apoptotic death of mouse sympathetic neurons deprived of NGF and that ROS is not involved in its activation in these cells.

Chrysin exerts neuroprotective effects against 3-Nitropropionic acid induced behavioral despair-Mitochondrial dysfunction and striatal apoptosis via upregulating Bcl-2 gene and downregulating Bax-Bad genes in male wistar rats

3-Nitropropionic acid (3-NP) is an irreversible inhibitor of mitochondrial complex-II that causes transcriptional dysregulation, bioenergetics failure, protein aggregation and oxidative damage similar to Huntington's disease (HD) pathogenesis. Chrysin, a bioactive flavonoid reported to have anti-inflammation, antioxidant, vasorelaxant and neuroprotective property. The present study was framed to determine the neuroprotective efficiency of chrysin upon 3-NP induced oxidative stress, mitochondrial dysfunctions and neurodegeneration. 3-NP (10mg/kg b.w. i.p.) administration for 14days exhibited significant (P<0.01) behavioral alterations, mitochondrial dysfunction and oxidative damages to biomolecules, finally causes cell death. Chrysin at 50mg/kg b.w. orally for 14days improved all the behavioral performances and regulated the complex activities in mitochondria. Further, chrysin diminished the oxidative stress markers (lipid peroxidation, nitrite and protein carbonyls) by significantly (P<0.01) improving the antioxidant status (superoxide dismutase, catalase and reduced glutathione) in striatal mitochondria. Indeed, chrysin prevents apoptosis by upregulating the Bcl-2 mRNA expression and downregulating the pro-apoptotic (Bax, Bad) mRNAs in 3-NP induced condition. Furthermore, the survival of striatal neurons against 3-NP toxicity was enhanced upon chrysin treatment which was evidenced by observing histopathological studies. Hence, the present study collectively suggests that the chrysin can serve as a potential therapeutic agent on 3-NP induced mitochondrial deficits and subsequent apoptosis.

Mitochondrial pathogenic mechanism and degradation in optineurin E50K mutation-mediated retinal ganglion cell degeneration

Mutations in optineurin (OPTN) are linked to the pathology of primary open angle glaucoma (POAG) and amyotrophic lateral sclerosis. Emerging evidence indicates that OPTN mutation is involved in accumulation of damaged mitochondria and defective mitophagy. Nevertheless, the role played by an OPTN E50K mutation in the pathogenic mitochondrial mechanism that underlies retinal ganglion cell (RGC) degeneration in POAG remains unknown. We show here that E50K expression induces mitochondrial fission-mediated mitochondrial degradation and mitophagy in the axons of the glial lamina of aged E50K^−tg mice in vivo. While E50K activates the Bax pathway and oxidative stress, and triggers dynamics alteration-mediated mitochondrial degradation and mitophagy in RGC somas in vitro, it does not affect transport dynamics and fission of mitochondria in RGC axons in vitro. These results strongly suggest that E50K is associated with mitochondrial dysfunction in RGC degeneration in synergy with environmental factors such as aging and/or oxidative stress.

The anti-oxidant and pro-oxidant dichotomy of Bcl-2

Across a wide spectrum of cellular redox status, there emerges a dichotomy of responses in terms of cell survival/proliferation and cell death. Of note, there is emerging evidence that the anti-apoptotic protein, Bcl-2, in addition to its conventional activity of titrating the pro-apoptotic effects of proteins such as Bax and Bak at the mitochondria, also impacts cell fate decisions via modulating cellular redox metabolism. In this regard, both pro- and anti-oxidant effects of Bcl-2 overexpression have been described under different conditions and cellular contexts. In this short review, we attempt to analyze existing observations and present a probable explanation for the seemingly conflicting redox regulating activity of Bcl-2 from the standpoint of its pro-survival function. The consequential effect(s) of the dual redox functions of Bcl-2 are also discussed, particularly from the viewpoint of developing novel therapeutic strategies against cancers rendered refractory due to the aberrant expression of Bcl-2.

Targeting TRPM2 Channels Impairs Radiation-Induced Cell Cycle Arrest and Fosters Cell Death of T Cell Leukemia Cells in a Bcl-2-Dependent Manner

Messenger RNA data of lymphohematopoietic cancer lines suggest a correlation between expression of the cation channel TRPM2 and the antiapoptotic protein Bcl-2. The latter is overexpressed in various tumor entities and mediates therapy resistance. Here, we analyzed the crosstalk between Bcl-2 and TRPM2 channels in T cell leukemia cells during oxidative stress as conferred by ionizing radiation (IR). To this end, the effects of TRPM2 inhibition or knock-down on plasma membrane currents, Ca²⁺ signaling, mitochondrial superoxide anion formation, and cell cycle progression were compared between irradiated (0–10 Gy) Bcl-2-overexpressing and empty vector-transfected Jurkat cells. As a result, IR stimulated a TRPM2-mediated Ca²⁺-entry, which was higher in Bcl-2-overexpressing than in control cells and which contributed to IR-induced G₂/M cell cycle arrest. TRPM2 inhibition induced a release from G₂/M arrest resulting in cell death. Collectively, this data suggests a pivotal function of TRPM2 in the DNA damage response of T cell leukemia cells. Apoptosis-resistant Bcl-2-overexpressing cells even can afford higher TRPM2 activity without risking a hazardous Ca²⁺-overload-induced mitochondrial superoxide anion formation.

Bax and caspases regulate increased production of mitochondria-derived reactive species in neuronal apoptosis: LACK of A role for depletion of cytochrome c from the mitochondrial electron transport chain

A Bax-dependent increase of reactive oxygen species (ROS) and other reactive species (RS) occurs after withdrawing NGF from mouse sympathetic neurons in cell culture. Possible mechanisms underlying the increased ROS/RS are leakage of electrons from the mitochondrial electron transport chain secondary to caspase cleavage of respiratory complexes or leakage secondary to depletion of cytochrome c from the chain. We previously demonstrated that deletion of Bax or caspase 3 from these cells reduces ROS/RS production to near baseline levels indicating a central role for both Bax and caspase 3 in generating the ROS/RS. Here we depleted cytochrome c to a similar level in neurons from wild type and bax hemizygous or knockout mice by NGF withdrawal or treatment with H₂O₂. Death was prevented with a caspase inhibitor that caused a partial reduction of ROS/RS levels but did not completely prevent the ROS/RS increase. ROS/RS was highest in bax wild-type cells, lowest in bax knockout cells, and at an intermediate level in the bax hemizygous cells. These and our previous findings indicate that Bax and caspase 3 are necessary for the increased ROS/RS after withdrawing NGF from these cells and that little or none of the increased ROS/RS are secondary to a depletion of cytochrome c from the electron transport chain.

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Bax lies upstream of all increased production of ROS by mitochondria in NGF-deprived sympathetic neurons.

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The broad-spectrum caspase inhibitor BAF blocks some but not all increased ROS after NGF withdrawal.

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Caspase 3 deletion blocks almost all of the increased ROS after NGF withdrawal suggesting that BAF does not block all caspase activity or that it has non-specific pro-oxidant effects.

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Depletion of cytochrome c from the electron transport chain contributes little or nothing to increased ROS after NGF withdrawal.

Reactive oxygen species are involved in BMP-induced dendritic growth in cultured rat sympathetic neurons

Previous studies have shown that bone morphogenetic proteins (BMPs) promote dendritic growth in sympathetic neurons; however, the downstream signaling molecules that mediate the dendrite promoting activity of BMPs are not well characterized. Here we test the hypothesis that reactive oxygen species (ROS)-mediated signaling links BMP receptor activation to dendritic growth. In cultured rat sympathetic neurons, exposure to any of the three mechanistically distinct antioxidants, diphenylene iodinium (DPI), nordihydroguaiaretic acid (NGA) or desferroxamine (DFO), blocked de novo BMP-induced dendritic growth. Addition of DPI to cultures previously induced with BMP to extend dendrites caused dendritic retraction while DFO and NGA prevented further growth of dendrites. The inhibition of the dendrite promoting activity of BMPs by antioxidants was concentration-dependent and occurred without altering axonal growth or neuronal cell survival. Antioxidant treatment did not block BMP activation of SMAD 1,5 as determined by nuclear localization of these SMADs. While BMP treatment did not cause a detectable increase in intracellular ROS in cultured sympathetic neurons as assessed using fluorescent indicator dyes, BMP treatment increased the oxygen consumption rate in cultured sympathetic neurons as determined using the Seahorse XF24 Analyzer, suggesting increased mitochondrial activity. In addition, BMPs upregulated expression of NADPH oxidase 2 (NOX2) and either pharmacological inhibition or siRNA knockdown of NOX2 significantly decreased BMP-7 induced dendritic growth. Collectively, these data support the hypothesis that ROS are involved in the downstream signaling events that mediate BMP7-induced dendritic growth in sympathetic neurons, and suggest that ROS-mediated signaling positively modulates dendritic complexity in peripheral neurons.

Ceramide-induced apoptosis in renal tubular cells: a role of mitochondria and sphingosine-1-phoshate

Ceramide is synthesized upon stimuli, and induces apoptosis in renal tubular cells (RTCs). Sphingosine-1 phosphate (S1P) functions as a survival factor. Thus, the balance of ceramide/S1P determines ceramide-induced apoptosis. Mitochondria play a key role for ceramide-induced apoptosis by altered mitochondrial outer membrane permeability (MOMP). Ceramide enhances oligomerization of pro-apoptotic Bcl-2 family proteins, ceramide channel, and reduces anti-apoptotic Bcl-2 proteins in the MOM. This process alters MOMP, resulting in generation of reactive oxygen species (ROS), cytochrome C release into the cytosol, caspase activation, and apoptosis. Ceramide regulates apoptosis through mitogen-activated protein kinases (MAPKs)-dependent and -independent pathways. Conversely, MAPKs alter ceramide generation by regulating the enzymes involving ceramide metabolism, affecting ceramide-induced apoptosis. Crosstalk between Bcl-2 family proteins, ROS, and many signaling pathways regulates ceramide-induced apoptosis. Growth factors rescue ceramide-induced apoptosis by regulating the enzymes involving ceramide metabolism, S1P, and signaling pathways including MAPKs. This article reviews evidence supporting a role of ceramide for apoptosis and discusses a role of mitochondria, including MOMP, Bcl-2 family proteins, ROS, and signaling pathways, and crosstalk between these factors in the regulation of ceramide-induced apoptosis of RTCs. A balancing role between ceramide and S1P and the strategy for preventing ceramide-induced apoptosis by growth factors are also discussed.

Neuroprotective mechanism of Lycium barbarum polysaccharides against hippocampal-dependent spatial memory deficits in a rat model of obstructive sleep apnea

Chronic intermittent hypoxia (CIH) is a hallmark of obstructive sleep apnea (OSA), which induces hippocampal injuries mediated by oxidative stress. This study aims to examine the neuroprotective mechanism of Lycium barbarum polysaccharides (LBP) against CIH-induced spatial memory deficits. Adult Sprague–Dawley rats were exposed to hypoxic treatment resembling a severe OSA condition for a week. The animals were orally fed with LBP solution (1mg/kg) daily 2 hours prior to hypoxia or in air for the control. The effect of LBP on the spatial memory and levels of oxidative stress, inflammation, endoplasmic reticulum (ER) stress, apoptosis and neurogenesis in the hippocampus was examined. There was a significant deficit in the spatial memory and an elevated level of malondialdehyde with a decreased expression of antioxidant enzymes (SOD, GPx-1) in the hypoxic group when compared with the normoxic control. In addition, redox-sensitive nuclear factor kappa B (NFКB) canonical pathway was activated with a translocation of NFКB members (p65, p50) and increased expression levels of NFКB-dependent inflammatory cytokines and mediator (TNFα, IL-1β, COX-2); also, a significantly elevated level of ER stress (GRP78/Bip, PERK, CHOP) and autophagic flux in the hypoxic group, leading to neuronal apoptosis in hippocampal subfields (DG, CA1, CA3). Remarkably, LBP administration normalized the elevated level of oxidative stress, neuroinflammation, ER stress, autophagic flux and apoptosis induced by hypoxia. Moreover, LBP significantly mitigated both the caspase-dependent intrinsic (Bax, Bcl2, cytochrome C, cleaved caspase-3) and extrinsic (FADD, cleaved caspase-8, Bid) signaling apoptotic cascades. Furthermore, LBP administration prevented the spatial memory deficit and enhanced the hippocampal neurogenesis induced by hypoxia. Our results suggest that LBP is neuroprotective against CIH-induced hippocampal-dependent spatial memory deficits by promoting hippocampal neurogenesis and negatively modulating the apoptotic signaling cascades activated by oxidative stress and inflammation.

Mitochondria-derived reactive oxygen species mediate caspase-dependent and -independent neuronal deaths

Mitochondrial dysfunction and oxidative stress are implicated in many neurodegenerative diseases. Mitochondria-targeted drugs that effectively decrease oxidative stress, protect mitochondrial energetics, and prevent neuronal loss may therefore lend therapeutic benefit to these currently incurable diseases. To investigate the efficacy of such drugs, we examined the effects of mitochondria-targeted antioxidants MitoQ10 and MitoE2 on neuronal death induced by neurotrophin deficiency. Our results indicate that MitoQ10 blocked apoptosis by preventing increased mitochondria-derived reactive oxygen species (ROS) and subsequent cytochrome c release, caspase activation, and mitochondrial damage in nerve growth factor (NGF)-deprived sympathetic neurons, while MitoE2 was largely ineffective. In this paradigm, the most proximal point of divergence was the ability of MitoQ10 to scavenge mitochondrial superoxide (O2(-)). MitoQ10 also prevented caspase-independent neuronal death in these cells demonstrating that the mitochondrial redox state significantly influences both apoptotic and nonapoptotic pathways leading to neuronal death. We suggest that mitochondria-targeted antioxidants may provide tools for delineating the role and significance of mitochondrial ROS in neuronal death and provide a new therapeutic approach for neurodegenerative conditions involving trophic factor deficits and multiple modes of cell death.

GM1 ganglioside activates ERK1/2 and Akt downstream of Trk tyrosine kinase and protects PC12 cells against hydrogen peroxide toxicity

Ganglioside GM1 at micro- and nanomolar concentrations was shown to increase the viability of pheochromocytoma PC12 cells exposed to hydrogen peroxide and diminish the accumulation of reactive oxygen species and oxidative inactivation of Na(+),K(+)-ATPase, the effects of micromolar GM1 being more pronounced than those of nanomolar GM1. These effects of GM1 were abolished by Trk receptor tyrosine kinase inhibitor and diminished by MEK1/2, phosphoinositide 3-kinase and protein kinase C inhibitors. Hydrogen peroxide activates Trk tyrosine kinase; Akt and ERK1/2 are activated downstream of this protein kinase. GM1 was found to activate Trk receptor tyrosine kinase in PC12 cells. GM1 (100 nM and 10 µM) increased the basal activity of Akt, but did not change Akt activity in cells exposed to hydrogen peroxide. Basal ERK1/2 activity in PC12 cells was increased by GM1 at a concentration of 10 µM, but not at nanomolar concentrations. Activation of ERK1/2 by hydrogen peroxide was enhanced by GM1 at a concentration of 10 µM and to a lesser extent at a concentration of 100 nM. Thus, the protective and metabolic effects of GM1 ganglioside on PC12 cells exposed to hydrogen peroxide appear to depend on the activation of Trk receptor tyrosine kinase and downstream activation of Akt and ERK1/2.

The characteristics of Bax inhibitor-1 and its related diseases

Bax inhibitor-1 (BI-1) is an evolutionarily-conserved endoplasmic reticulum protein. The expression of BI-1 in mammalian cells suppresses apoptosis induced by Bax, a pro-apoptotic member of the Bcl-2 family. BI-1 has been shown to be associated with calcium (Ca(2+)) levels, reactive oxygen species (ROS) production, cytosolic acidification, and autophagy as well as endoplasmic reticulum stress signaling pathways. According to both in vitro and clinical studies, BI-1 promotes the characteristics of cancers. In other diseases, BI-1 has also been shown to regulate insulin resistance, adipocyte differentiation, hepatic dysfunction and depression. However, the roles of BI-1 in these disease conditions are not fully consistent among studies. Until now, the molecular mechanisms of BI-1 have not directly explained with regard to how these conditions can be regulated. Therefore, this review investigates the physiological role of BI-1 through molecular mechanism studies and its application in various diseases.

The analog of Ginkgo biloba extract 761 is a protective factor of cognitive impairment induced by chronic fluorosis

Ginkgo biloba extract EGb761 is widely used to treat patients with learning and memory impairment in Alzheimer's disease and Parkinson's disease in China. However, it is not yet clear whether the analog of EGb761 (EGb) has a protective effect on the learning and memory damage induced by chronic fluorosis. In this study, 30 Wistar rats were randomly divided into three groups: a control group, a sodium fluoride (NaF) + EGb group, and a NaF group. The rats were administered 0.5 ml water containing NaF (100 mg/l) and EGb (120 mg/kg) per day via gavage. After 3 months, the rats' capacity for learning and memory was tested using a Y-maze. Damage to hippocampal neurons was evaluated by histological examination of the CA3 area. Superoxide dismutase (SOD) activity and the levels of glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) were measured. Furthermore, the expression levels of Bcl-2 and Bax and the levels of cleaved Caspase3 in the hippocampus were evaluated by RT-PCR and Western blotting. The results showed that EGb could improve learning and memory abilities, enhance the activities of SOD and GSH-Px, attenuate the level of MDA, upregulate the ratio of Bcl-2/Bax, and downregulate the level of cleaved Caspase3.

The mitochondria-targeted antioxidant MitoQ prevents loss of spatial memory retention and early neuropathology in a transgenic mouse model of Alzheimer's disease

Considerable evidence suggests that mitochondrial dysfunction and oxidative stress contribute to the progression of Alzheimer's disease (AD). We examined the ability of the novel mitochondria-targeted antioxidant MitoQ (mitoquinone mesylate: [10-(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4-cycloheexadienl-yl) decyl triphenylphosphonium methanesulfonate]) to prevent AD-like pathology in mouse cortical neurons in cell culture and in a triple transgenic mouse model of AD (3xTg-AD). MitoQ attenuated β-amyloid (Aβ)-induced neurotoxicity in cortical neurons and also prevented increased production of reactive species and loss of mitochondrial membrane potential (Δψ(m)) in them. To determine whether the mitochondrial protection conferred by MitoQ was sufficient to prevent the emergence of AD-like neuropathology in vivo, we treated young female 3xTg-AD mice with MitoQ for 5 months and analyzed the effect on the progression of AD-like pathologies. Our results show that MitoQ prevented cognitive decline in these mice as well as oxidative stress, Aβ accumulation, astrogliosis, synaptic loss, and caspase activation in their brains. The work presented herein suggests a central role for mitochondria in neurodegeneration and provides evidence supporting the use of mitochondria-targeted therapeutics in diseases involving oxidative stress and metabolic failure, namely AD.

Dietary and behavioral interventions protect against age related activation of caspase cascades in the canine brain

Lifestyle interventions such as diet, exercise, and cognitive training represent a quietly emerging revolution in the modern approach to counteracting age-related declines in brain health. Previous studies in our laboratory have shown that long-term dietary supplementation with antioxidants and mitochondrial cofactors (AOX) or behavioral enrichment with social, cognitive, and exercise components (ENR), can effectively improve cognitive performance and reduce brain pathology of aged canines, including oxidative damage and Aβ accumulation. In this study, we build on and extend our previous findings by investigating if the interventions reduce caspase activation and ceramide accumulation in the aged frontal cortex, since caspase activation and ceramide accumulation are common convergence points for oxidative damage and Aβ, among other factors associated with the aged and AD brain. Aged beagles were placed into one of four treatment groups: CON – control environment/control diet, AOX– control environment/antioxidant diet, ENR – enriched environment/control diet, AOX/ENR– enriched environment/antioxidant diet for 2.8 years. Following behavioral testing, brains were removed and frontal cortices were analyzed to monitor levels of active caspase 3, active caspase 9 and their respective cleavage products such as tau and semaphorin7a, and ceramides. Our results show that levels of activated caspase-3 were reduced by ENR and AOX interventions with the largest reduction occurring with combined AOX/ENR group. Further, reductions in caspase-3 correlated with reduced errors in a reversal learning task, which depends on frontal cortex function. In addition, animals treated with an AOX arm showed reduced numbers of cells expressing active caspase 9 or its cleavage product semaphorin 7A, while ENR (but not AOX) reduced ceramide levels. Overall, these data demonstrate that lifestyle interventions curtail activation of pro-degenerative pathways to improve cellular health and are the first to show that lifestyle interventions can regulate caspase pathways in a higher animal model of aging.

Redox homeostasis, oxidative stress and disuse muscle atrophy

A pivotal role has been ascribed to oxidative stress in determining the imbalance between protein synthesis and degradation leading to muscle atrophy in many pathological conditions and in disuse. However, a large variability in disuse-induced alteration of redox homeostasis through muscles, models and species emerges from the literature. Whereas the causal role of oxidative stress appears well established in the mechanical ventilation model, findings are less compelling in the hindlimb unloaded mice and very limited in humans. The mere coexistence of muscle atrophy, indirect indexes of increased reactive oxygen species (ROS) production and impairment of antioxidant defence systems, in fact, does not unequivocally support a causal role of oxidative stress in the phenomenon. We hypothesise that in some muscles, models and species only, due to a large redox imbalance, the leading phenomena are activation of proteolysis and massive oxidation of proteins, which would become more susceptible to degradation. In other conditions, due to a lower extent and variable time course of ROS production, different ROS-dependent, but also -independent intracellular pathways might dominate determining the variable extent of atrophy and even dispensable protein oxidation. The ROS production and removal are complex and finely tuned phenomena. They are indeed important intracellular signals and redox balance maintains normal muscle homeostasis and can underlie either positive or negative adaptations to exercise. A precise approach to determine the levels of ROS in living cells in various conditions appears to be of paramount importance to define and support such hypotheses.