Mitochondrial permeability transition in apoptosis and necrosis

Assessment of Mononuclear/Dinuclear copper acylhydrazone complexes for lung cancer treatment

Non-platinum metal-based complexes have good potential for cancer treatment. Here, we designed and synthesized five hydrazone copper(II) complexes, [Cu2(HL)2Cl2] 1A, [Cu2(HL)2(NO3)H2O]·NO3 2A, [Cu2(HL)2Br2] 3A, [Cu(L)pyridine] 1B and [Cu(HL)(pyridine)Br] 3B, and evaluated their anti-lung cancer activities. MTT experiments revealed that these copper(II) complexes exhibit higher anticancer activity than cisplatin. Mechanism studies revealed that complex 3A induced G1 phase cell cycle arrest, and induced cell apoptosis via reactive oxygen species (ROS)-mediated mitochondrial dysfunction. Scratch wound healing assay was also performed, revealing that complex 3A have good anti-cell migration activity. Hemolysis assays showed good blood biocompatibility of complex 3A. Furthermore, complex 3A can significantly inhibit the proliferation of A549 3D tumor spheroid. An in vivo anticancer study showed that complex 3A could delays the growth of A549 tumor xenografts with lower systemic toxicity. These results highlight the great possibility of developing highly active copper complexes as anti-lung cancer agents.

Boosting Sono-immunotherapy of Prostate Carcinoma through Amplifying Domino-Effect of Mitochondrial Oxidative Stress Using Biodegradable Cascade-Targeting Nanocomposites

Sono-immunotherapy faces challenges from poor immunogenicity and low response rate due to complex biological barriers. Herein, we prepared MCTH nanocomposites (NCs) consisting of disulfide bonds (S-S) doped mesoporous organosilica (MONs), Cu-modified protoporphyrin (CuPpIX), mitochondria-targeting triphenylphosphine (TPP), and CD44-targeting hyaluronic acid (HA). MCTH NCs efficiently accumulate at the tumor site due to the overexpressed CD44 receptors on the membrane of the cancer cells. Under the function of HAase and glutathione (GSH), MCTH degrades and exposes TPP to deliver CuPpIX to the mitochondrial site and induce a reactive oxygen species (ROS) burst in situ under ultrasound irradiations, thereby causing severe mitochondria dysfunction. This cascade-targeting ability of MCTH NCs not only reinforces oxidative stress in cancer cells but also amplifies immunogenic cell death (ICD) to stimulate the body's immune response and alleviate the tumor immunosuppressive microenvironment. These NCs significantly enhance the infiltration of immune cells into the tumor, particularly CD8+ T cells, for a powerful antitumor sono-immunotherapy. The proposed cascade-targeting strategy holds promise for strengthening sono-immunotherapy for prostate cancer treatment and overcoming the limitations of traditional immunotherapy.

Oxidative stress promotes cytotoxicity in human cancer cell lines exposed to Escallonia spp. extracts

BACKGROUND

Standard cancer treatments show a lack of selectivity that has led to the search for new strategies against cancer. The selective elimination of cancer cells modulating the redox environment, known as "selective oxycution", has emerged as a viable alternative. This research focuses on characterizing the unexplored Escallonia genus plant extracts and evaluating their potential effects on cancer's redox balance, cytotoxicity, and activation of death pathways.

METHODS

36 plant extracts were obtained from 4 different species of the Escallonia genus (E. illinita C. Presl, E. rubra (Ruiz & Pav.) Pers., E. revoluta (Ruiz & Pav.) Pers., and E. pulverulenta (Ruiz & Pav.) Pers.), which were posteriorly analyzed by their phytoconstituents, antioxidant capacity, and GC-MS. Further, redox balance assays (antioxidant enzymes, oxidative damage, and transcription factors) and cytotoxic effects (SRB, ∆Ψmt, and caspases actives) of those plant extracts were analyzed on four cell lines (HEK-293T, MCF-7, HT-29, and PC-3).

RESULTS

36 plant extracts were obtained, and their phytoconstituents and antioxidant capacity were established. Further, only six extracts had EC50 values < 10 µg*mL- 1, indicating high toxicity against the tested cells. From those, two plant extracts were selective against different cancer cell lines: the hexane extract of E. pulverulenta´s stem was selective for HT-29, and the ethyl acetate extract of E. rubra´s stem was selective for PC-3. Both extracts showed unbalanced redox effects and promoted selective cell death.

CONCLUSIONS

This is the first study proving "selective oxycution" induced by Chilean native plant extracts.

Multifaceted roles of mitochondria in wound healing and chronic wound pathogenesis

Mitochondria are intracellular organelles that play a critical role in numerous cellular processes including the regulation of metabolism, cellular stress response, and cell fate. Mitochondria themselves are subject to well-orchestrated regulation in order to maintain organelle and cellular homeostasis. Wound healing is a multifactorial process that involves the stringent regulation of several cell types and cellular processes. In the event of dysregulated wound healing, hard-to-heal chronic wounds form and can place a significant burden on healthcare systems. Importantly, treatment options remain limited owing to the multifactorial nature of chronic wound pathogenesis. One area that has received more attention in recent years is the role of mitochondria in wound healing. With regards to this, current literature has demonstrated an important role for mitochondria in several areas of wound healing and chronic wound pathogenesis including metabolism, apoptosis, and redox signalling. Additionally, the influence of mitochondrial dynamics and mitophagy has also been investigated. However, few studies have utilised patient tissue when studying mitochondria in wound healing, instead using various animal models. In this review we dissect the current knowledge of the role of mitochondria in wound healing and discuss how future research can potentially aid in the progression of wound healing research.

In Vitro and In Vivo Relevant Antineoplastic Activity of Platinum(II) Complexes toward Triple-Negative MDA-MB-231 Breast Cancer Cell Line

Two platinum complexes [Pt(HL3)Cl]·H₂O (3) and [Pt(HL4)Cl]·H₂O (4) containing α- and β-naphthyl groups, respectively, were investigated in more detail in vitro and in vivo for antineoplastic activity. The cytotoxicity activity induced by these platinum(II) compounds against breast cancer (MDA-MB-231 and MCF-7), lung (A549), prostate (PC3), pancreas (BXPC-3), and normal peripheral blood mononuclear (PBMC) cells were evaluated by MTT assay. The cell viability MTT assay showed that complex (4) was more cytotoxic to all cancer cell lines tested and less cytotoxic against human PBMC. Therefore, complex (4) was selected to further investigate the mechanism of cytotoxic effects involved against MDA-MB-231 cell line (human triple-negative breast cancer). Sub-G1 analysis of the cell cycle showed that this complex induces cell death by apoptosis due to the cell loss of DNA content detected in flow cytometry. The cytotoxic effect induced by complex (4) was associated with the capability of the complex to induce mitochondrial membrane depolarization, as well as increase ROS levels and caspase activation, as a result of the activation of both extrinsic and intrinsic apoptosis pathways. Ultrastructural alterations were observed using scanning and transmission electron microscopy (SEM and TEM), such as membrane blebbing, filopodia reduction, empty mitochondrial matrix, and DNA fragmentation. Furthermore, complex (4) was tested in an MDA-MB-231 tumor nodule xenograft murine model and demonstrated a remarkable reduction in tumor size in BALB/c nude mice, when compared to the control animals.

Cyclosporine A regulates PMN-MDSCs viability and function through MPTP in acute GVHD: Old medication, new target

Myeloid-derived suppressor cells (MDSCs), a population of myeloid lineage cells with immunosuppressive capacity, can mitigate acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We previously found that the immunosuppressive function of polymorphonuclear population (PMN-MDSCs) was impaired in aGVHD milieu. The aim of this study was to explore the intrinsic mechanism regulating the fate and function of donor-derived PMN-MDSCs during allo-HSCT. We firstly found that mitochondrial permeability transition pore (MPTP) opened in the PMN-MDSCs in response to the intense inflammatory environment of aGVHD, which induced mitochondrial damage, oxidative stress, and apoptosis of PMN-MDSCs. Inhibiting MPTP opening by a traditional immunosuppressant, cyclosporine A (CsA), could restore the immunosuppressive function and viability of PMN-MDSCs in vitro and in vivo, which reveals a new mechanism of CsA application.

COL-3-Induced Molecular and Ultrastructural Alterations in K562 Cells

Tetracycline-3 (4-dedimethylamino sancycline, COL-3) is a non-antibiotic tetracycline derivative. COL-3 exerts potent anti-metalloproteinase activity and its antitumor effects have been reported both in vitro and in vivo. In this study, we investigated the mechanisms of COL-3-induced cytotoxicity in a chronic myeloid leukemia cell line, K562, characterized by the BCR-ABL fusion protein. COL-3 induced K562 cell death in a concentration-dependent manner with an IC50 of 10.8 µg/mL and exhibited features of both apoptosis and necrosis. However, flow cytometry analysis revealed that necrotic cells dominated over the early and late apoptotic cells upon treatment with COL-3. Transmission electron microscopy analysis in combination with Western blotting (WB) analysis revealed early mitochondrial swelling accompanied by the early release of cytochrome c and truncated apoptosis inducing factor (tAIF). In addition, ultrastructural changes were detected in the endoplasmic reticulum (ER). COL-3 affected the levels of glucose-regulated protein-94 (GRP94) and resulted in m-calpain activation. DNA double strand breaks as a signature for DNA damage was also confirmed using an antibody against γH2AX. WB analyses did not demonstrate caspase activation, while Bcl-xL protein remained unaffected. In conclusion, COL-3-induced cell death involves DNA damage as well as mitochondrial and ER perturbation with features of paraptosis and programmed necrosis.

Mechanisms of Regulated Cell Death: Current Perspectives

Balancing cell survival and cell death is fundamental to development and homeostasis. Cell death is regulated by multiple interconnected signaling pathways and molecular mechanisms. Regulated cell death (RCD) is implicated in fundamental processes such as organogenesis and tissue remodeling, removal of unnecessary structures or cells, and regulation of cell numbers. RCD can also be triggered by exogenous perturbations of the intracellular or extracellular microenvironment when the adaptive processes that respond to stress fail. During the past few years, many novel forms of non-apoptotic RCD have been identified, and the characterization of RCD mechanisms at a molecular level has deepened our understanding of diseases encountered in human and veterinary medicine. Given the complexity of these processes, it has become clear that the identification of RCD cannot be based simply on morphologic characteristics and that descriptive and diagnostic terms presently used by pathologists-such as individual cell apoptosis or necrosis-appear inadequate and possibly misleading. In this review, the current understanding of the molecular machinery of each type of non-apoptotic RCD mechanisms is outlined. Due to the continuous discovery of new mechanisms or nuances of previously described processes, the limitations of the terms apoptosis and necrosis to indicate microscopic findings are also reported. In addition, the need for a standard panel of biomarkers and functional tests to adequately characterize the underlying RCD and its role as a mechanism of disease is considered.

Assessment of Neuroprotective Effects of Low-Intensity Transcranial Ultrasound Stimulation in a Parkinson's Disease Rat Model by Fractional Anisotropy and Relaxation Time T2∗ Value

Background: Low-intensity transcranial ultrasound (LITUS) may have a therapeutic effect on Parkinson's disease (PD) patients to some extent. Fractional anisotropy (FA) and relaxation time T2^∗ that indicate the integrity of fiber tracts and iron concentrations in brain tissue have been used to evaluate the therapeutic effects of LITUS. Purpose: This study aims to use FA and T2^∗ values to evaluate the therapeutic effects of LITUS in a PD rat model. Materials and Methods: Twenty Sprague-Dawley rats were randomly divided into a hemi-PD group (n = 10) and a LITUS group (n = 10). Single-shot spin echo echo-planar imaging and fast low-angle shot T2WI sequences at 3.0 T were used. The FA and T2^∗ values on the right side of the substantia nigra (SN) pars compacta were measured to evaluate the therapeutic effect of LITUS in the rats. Results: One week after PD-like signs were induced in the rats, the FA value in the LITUS group was significantly larger compared with the PD group (0.214 ± 0.027 vs. 0.340 ± 0.032, t = 2.864, P = 0.011). At the 5th and 6th weeks, the FA values in the LITUS group were significantly smaller compared with the PD group (5th week: 0.290 ± 0.037 vs. 0.405 ± 0.027, t = 2.385, P = 0.030; 6th week: 0.299 ± 0.021 vs. 0.525 ± 0.028, t = 6.620, P < 0.0001). In the 5th and 6th weeks, the T2^∗ values in the injected right SN of the LITUS group were significantly higher compared with the PD group (5th week, 12.169 ± 0.826 in the LITUS group vs. 7.550 ± 0.824 in the PD group; 6th week, 11.749 ± 0.615 in the LITUS group vs. 7.550 ± 0.849 in the PD group). Conclusion: LITUS had neuroprotective effects and can reduce the damage of 6-OHDA-induced neurotoxicity in hemi-PD rats. The combination of FA and T2^∗ assessments can potentially serve as a new and effective method to evaluate the therapeutic effects of LITUS.

Chemical Composition, Antioxidant and Anticancer Activities of Leptocarpha rivularis DC Flower Extracts

An evaluation of antioxidant and anticancer activity was screened in Leptocarpha rivularis DC flower extracts using four solvents (n-hexane (Hex), dichloromethane (DCM), ethyl acetate (AcOEt), and ethanol (EtOH)). Extracts were compared for total extract flavonoids and phenol contents, antioxidant activity (2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), ferric reducing antioxidant potential (FRAP), total reactive antioxidant properties (TRAP) and oxygen radical absorbance capacity (ORAC)) across a determined value of reduced/oxidized glutathione (GSH/GSSG), and cell viability (the sulforhodamine B (SRB) assay). The most active extracts were analyzed by chromatographic analysis (GC/MS) and tested for apoptotic pathways. Extracts from Hex, DCM and AcOEt reduced cell viability, caused changes in cell morphology, affected mitochondrial membrane permeability, and induced caspase activation in tumor cell lines HT-29, PC-3, and MCF-7. These effects were generally less pronounced in the HEK-293 cell line (nontumor cells), indicating clear selectivity towards tumor cell lines. We attribute likely extract activity to the presence of sesquiterpene lactones, in combination with other components like steroids and flavonoids.

Neuroprotective Effects of Activated Protein C Involve the PARP/AIF Pathway against Oxygen-Glucose Deprivation in SH-SY5Y Cells

Protein C, a member of the zymogen family of serine proteases in plasma, is one of the several vitamin K dependent glycoproteins known to induce anti-apoptotic activity. However, the target molecule involved in the mechanism needs to be investigated. We sought to investigate the pathways involved in the anti-apoptotic role of activated protein C (APC) on oxygen-glucose deprivation (OGD) induced ischemic conditions in in-vitro SH-SY5Y cells. SH-SY5Y cells were exposed to OGD in an airtight chamber containing 95% N₂ and 5% CO₂ and media deprived of glucose for 4 h following 24 h of reoxygenation. The cell toxicity, viability, expression of receptors such as endothelial cell protein C receptor (EPCR), protease-activated receptor (PAR)1, PAR3, and apoptosis-related proteins B-cell lymphoma 2 (BCL-2), BCL-2-like protein 4 (Bax), Poly [ADP-ribose] polymerase-1 (PARP-1) were assessed. Administration of APC decreased the cellular injury when compared to the OGD exposed group in a dose-dependent manner and displayed increased expression of PAR-1, PAR-3, and EPCR. The APC treatment leads to a reduction in PARP-1 expression and cleavage and apoptosis-inducing factor (AIF) expression. The reduction of caspase-3 activity and PARP-1 and AIF expression following APC administration results in restoring mitochondrial function with decreased cellular injury and apoptosis. Our results suggested that APC has potent protective effects against in-vitro ischemia in SH-SY5Y cells by modulating mitochondrial function.

The role of cell type-specific mitochondrial dysfunction in the pathogenesis of Alzheimer's disease

The decrease of metabolism in the brain has been observed as the important lesions of Alzheimer’s disease (AD) from the early stages of diagnosis. The cumulative evidence has reported that the failure of mitochondria, an organelle involved in diverse biological processes as well as energy production, maybe the cause or effect of the pathogenesis of AD. Both amyloid and tau pathologies have an impact upon mitochondria through physical interaction or indirect signaling pathways, resulting in the disruption of mitochondrial function and dynamics which can trigger AD. In addition, mitochondria are involved in different biological processes depending on the specific functions of each cell type in the brain. Thus, it is necessary to understand mitochondrial dysfunction as part of the pathological phenotypes of AD according to each cell type. In this review, we summarize that 1) the effects of AD pathology inducing mitochondrial dysfunction and 2) the contribution of mitochondrial dysfunction in each cell type to AD pathogenesis.

A Multiparametric Study of Internalization of Fullerenol C60(OH)36 Nanoparticles into Peripheral Blood Mononuclear Cells: Cytotoxicity in Oxidative Stress Induced by Ionizing Radiation

The aim of this study was to investigate the uptake and accumulation of fullerenol C₆₀(OH)₃₆ into peripheral blood mononuclear cells (PBMCs). Some additional studies were also performed: measurement of fullerenol nanoparticle size, zeta potential, and the influence of fullerenol on the ionizing radiation-induced damage to PMBCs. Fullerenol C₆₀(OH)₃₆ demonstrated an ability to accumulate in PBMCs. The accumulation of fullerenol in those cells did not have a significant effect on cell survival, nor on the distribution of phosphatidylserine in the plasma membrane. However, fullerenol-induced depolarization of the mitochondrial membrane proportional to the compound level in the medium was observed. Results also indicated that increased fullerenol level in the medium was associated with its enhanced transport into cells, corresponding to its influence on the mitochondrial membrane. The obtained results clearly showed the ability of C₆₀(OH)₃₆ to enter cells and its effect on PBMC mitochondrial membrane potential. However, we did not observe radioprotective properties of fullerenol under the conditions used in our study.

TNF Induces Pathogenic Programmed Macrophage Necrosis in Tuberculosis through a Mitochondrial-Lysosomal-Endoplasmic Reticulum Circuit

Necrosis of infected macrophages constitutes a critical pathogenetic event in tuberculosis by releasing mycobacteria into the growth-permissive extracellular environment. In zebrafish infected with Mycobacterium marinum or Mycobacterium tuberculosis, excess tumor necrosis factor triggers programmed necrosis of infected macrophages through the production of mitochondrial reactive oxygen species (ROS) and the participation of cyclophilin D, a component of the mitochondrial permeability transition pore. Here, we show that this necrosis pathway is not mitochondrion-intrinsic but results from an inter-organellar circuit initiating and culminating in the mitochondrion. Mitochondrial ROS induce production of lysosomal ceramide that ultimately activates the cytosolic protein BAX. BAX promotes calcium flow from the endoplasmic reticulum into the mitochondrion through ryanodine receptors, and the resultant mitochondrial calcium overload triggers cyclophilin-D-mediated necrosis. We identify ryanodine receptors and plasma membrane L-type calcium channels as druggable targets to intercept mitochondrial calcium overload and necrosis of mycobacterium-infected zebrafish and human macrophages.

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TNF induces mitochondrial ROS to cause necrosis of mycobacterium-infected macrophages

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Mitochondrial ROS activate lysosomal enzymes that lead to BAX activation

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BAX activates ER ryanodine receptors to cause Ca²⁺ flow into the mitochondrion

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Drugs preventing mitochondrial Ca²⁺ overload prevent pathogenic macrophage necrosis in TB

Preischemic autologous mitochondrial transplantation by intracoronary injection for myocardial protection

OBJECTIVE

To investigate preischemic intracoronary autologous mitochondrial transplantation (MT) as a therapeutic strategy for prophylactic myocardial protection in a porcine model of regional ischemia-reperfusion injury (IRI).

METHODS

The left coronary artery was cannulated in Yorkshire pigs (n = 26). Mitochondria (1 × 10⁹) or buffer (vehicle [Veh]) were delivered as a single bolus (MT_S) or serially (10 injections over 60 minutes; MT_SS). At 15 minutes after injection, the heart was subjected to temporary regional ischemia (RI) by snaring the left anterior descending artery. After 30 minutes of RI, the snare was released, and the heart was reperfused for 120 minutes.

RESULTS

Coronary blood flow (CBF) and myocardial function were increased temporarily during the pre-RI period. Following 30 minutes of RI, MT_S and MT_SS hearts had significantly increased CBF that persisted throughout reperfusion (Veh vs MT_S and MT_SS; P = .04). MT_S and MT_SS showed a significantly enhanced ejection fraction (Veh vs MT_S, P < .001; Veh vs MT_SS, P = .04) and developed pressure (Veh vs MT_S, P < .001; Veh vs MT_SS, P = .03). Regional function, assessed through segmental shortening (Veh vs MT_S, P = .03; Veh vs MT_SS, P < .001), fractional shortening (Veh vs MT_S, P < .001; Veh vs MT_SS, P = .04), and strain analysis (Veh vs MT_S, P = .002; Veh vs MT_SS, P = .003), was also significantly improved. Although there was no difference in the area at risk between treatment groups, infarct size was significantly reduced in both MT groups (Veh vs MT_S and MT_SS, P < .001).

CONCLUSIONS

Preischemic MT by single or serial intracoronary injections provides prophylactic myocardial protection from IRI, significantly decreasing infarct size and enhancing global and regional function.

The Mitochondrial Translocator Protein and the Emerging Link Between Oxidative Stress and Arrhythmias in the Diabetic Heart

The mitochondrial translocator protein (TSPO) is a key outer mitochondrial membrane protein that regulates the activity of energy-dissipating mitochondrial channels in response to oxidative stress. In this article, we provide an overview of the role of TSPO in the systematic amplification of reactive oxygen species (ROS) through an autocatalytic process known as ROS-induced ROS-release (RIRR). We describe how this TSPO-driven process destabilizes the mitochondrial membrane potential leading to electrical instability at the cellular and whole heart levels. Finally, we provide our perspective on the role of TSPO in the pathophysiology of diabetes, in general and diabetes-related arrhythmias, in particular.

TTB2 induces apoptosis in Ewing sarcoma cells

A steroidal saponin named pennogenin 3-O-α-L-rhamnopyranosyl-(1→2) [α-L-rhamnopyranosyl-(1→4)]-β-D-glucoyranoside(TTB2) has been successfully separated from the n-BuOH extracts of Trillium tschonoskii Maxim and is able to induce cytotoxicity to some types cancer cells. The present study aimed to investigate how this novel saponinin duces cytotoxicity in malignant sarcoma cells and to clarify its molecular mechanisms of action. It was determined this steroidal saponin induced the apoptosis in Rh1 cells and activated caspase-3 and caspase-9. Additionally, it disrupted the mitochondrial membrane potential and altered the expression of bax and bcl-2. Thus, the results of present study identified that an anticancer saponin isolated from Trillium tschonoskii Maxim may be developed as a potential novel therapeutic strategy to treat certain types of cancer, including lung cancer and lung sarcoma.

Mitochondrial membrane potential

The mitochondrial membrane potential (ΔΨm) generated by proton pumps (Complexes I, III and IV) is an essential component in the process of energy storage during oxidative phosphorylation. Together with the proton gradient (ΔpH), ΔΨm forms the transmembrane potential of hydrogen ions which is harnessed to make ATP. The levels of ΔΨm and ATP in the cell are kept relatively stable although there are limited fluctuations of both these factors that can occur reflecting normal physiological activity. However, sustained changes in both factors may be deleterious. A long-lasting drop or rise of ΔΨm vs normal levels may induce unwanted loss of cell viability and be a cause of various pathologies. Among other factors, ΔΨm plays a key role in mitochondrial homeostasis through selective elimination of dysfunctional mitochondria. It is also a driving force for transport of ions (other than H+) and proteins which are necessary for healthy mitochondrial functioning. We propose additional potential mechanisms for which ΔΨm is essential for maintenance of cellular health and viability and provide recommendations how to accurately measure ΔΨm in a cell and discuss potential sources of artifacts.

Salvianolic Acid A Protects Neonatal Cardiomyocytes Against Hypoxia/Reoxygenation-Induced Injury by Preserving Mitochondrial Function and Activating Akt/GSK-3β Signals

OBJECTIVE

To investigate the effects of salvianolic acid A (SAA) on cardiomyocyte apoptosis and mitochondrial dysfunction in response to hypoxia/reoxygenation (H/R) injury and to determine whether the Akt signaling pathway might play a role.

METHODS

An in vitro model of H/R injury was used to study outcomes on primary cultured neonatal rat cardiomyocytes. The cardiomyocytes were treated with 12.5, 25, 50 μg/mL SAA at the beginning of hypoxia and reoxygenation, respectively. Adenosine triphospate (ATP) and reactive oxygen species (ROS) levels were assayed. Cell apoptosis was evaluated by flow cytometry and the expression of cleaved-caspase 3, Bax and Bcl-2 were detected by Western blotting. The effects of SAA on mitochondrial dysfunction were examined by determining the mitochondrial membrane potential (△Ψm) and mitochondrial permeability transition pore (mPTP), followed by the phosphorylation of Akt (p-Akt) and GSK-3β (p-GSK-3β), which were measured by Western blotting.

RESULTS

SAA significantly preserved ATP levels and reduced ROS production. Importantly, SAA markedly reduced the number of apoptotic cells and decreased cleaved-caspase 3 expression levels, while also reducing the ratio of Bax/Bcl-2. Furthermore, SAA prevented the loss of △Ψm and inhibited the activation of mPTP. Western blotting experiments further revealed that SAA significantly increased the expression of p-Akt and p-GSK-3β, and the increase in p-GSK-3β expression was attenuated after inhibition of the Akt signaling pathway with LY294002.

CONCLUSION

SAA has a protective effect on cardiomyocyte H/R injury; the underlying mechanism may be related to the preservation of mitochondrial function and the activation of the Akt/GSK-3β signaling pathway.

Withaferin A Induces ROS-Mediated Paraptosis in Human Breast Cancer Cell-Lines MCF-7 and MDA-MB-231

Advancement in cancer therapy requires a better understanding of the detailed mechanisms that induce death in cancer cells. Besides apoptosis, themode of other types of cell death has been increasingly recognized in response to therapy. Paraptosis is a non-apoptotic alternative form of programmed cell death, morphologically) distinct from apoptosis and autophagy. In the present study, Withaferin-A (WA) induced hyperpolarization of mitochondrial membrane potential and formation of many cytoplasmic vesicles. This was due to progressive swelling and fusion of mitochondria and dilation of endoplasmic reticulum (ER), forming large vacuolar structures that eventually filled the cytoplasm in human breast cancer cell-lines MCF-7 and MDA-MB-231. The level of indigenous paraptosis inhibitor, Alix/AIP-1 (Actin Interacting Protein-1) was down-regulated by WA treatment. Additionally, prevention of WA-induced cell death and vacuolation on co-treatment with protein-synthesis inhibitor indicated requirement of de-novo protein synthesis. Co-treatment with apoptosis inhibitor resulted in significant augmentation of WA-induced death in MCF-7 cells, while partial inhibition in MDA-MB-231 cells; implyingthat apoptosis was not solely responsible for the process.WA-mediated cytoplasmic vacuolationcould not be prevented by autophagy inhibitor wortmanninas well, claiming this process to be a non-autophagic one. Early induction of ROS (Reactive Oxygen Species)by WA in both the cell-lines was observed. ROS inhibitorabrogated the effect of WA on: cell-death, expression of proliferation-associated factor andER-stress related proteins,splicing of XBP-1 (X Box Binding Protein-1) mRNA and formation of paraptotic vacuoles.All these results conclusively indicate thatWA induces deathin bothMCF-7 and MDA-MB-231 cell lines byROS-mediated paraptosis.

Mitochondrial drug targets in neurodegenerative diseases

Growing evidence suggests that mitochondrial dysfunction is the main culprit in neurodegenerative diseases. Given the fact that mitochondria participate in diverse cellular processes, including energetics, metabolism, and death, the consequences of mitochondrial dysfunction in neuronal cells are inevitable. In fact, new strategies targeting mitochondrial dysfunction are emerging as potential alternatives to current treatment options for neurodegenerative diseases. In this review, we focus on mitochondrial proteins that are directly associated with mitochondrial dysfunction. We also examine recently identified small molecule modulators of these mitochondrial targets and assess their potential in research and therapeutic applications.

Advanced oxidation protein products induce apoptosis of human chondrocyte through reactive oxygen species-mediated mitochondrial dysfunction and endoplasmic reticulum stress pathways

Advanced oxidation production products (AOPPs) have been confirmed to accumulate in patients with rheumatoid arthritis (RA). Previous study demonstrated that AOPPs could accelerate cartilage destruction in rabbit arthritis model. However, the effect of AOPP stimulation on apoptosis of human chondrocyte and the underlying mechanisms remains unclear. This study demonstrated that exposure of chondrocyte to AOPPs resulted in cell apoptosis. AOPP stimulation triggered reactive oxygen species (ROS) production, which induced mitochondrial dysfunction and endoplasmic reticulum stress (ER stress) resulted in caspase activation. Furthermore, an antioxidant, N-acetylcysteine, markedly blocked these signals. Our study demonstrated that AOPPs induce apoptosis via ROS-related mitochondria- and ER-dependent signals in human chondrocyte. Targeting AOPP-triggered ROS generation might be as a promising option for patients with RA.

Blocking mPTP on Neural Stem Cells and Activating the Nicotinic Acetylcholine Receptor α7 Subunit on Microglia Attenuate Aβ-Induced Neurotoxicity on Neural Stem Cells

β-Amyloid (Aβ) can stimulate microglia to release a variety of proinflammatory cytokines and induce neurotoxicity. Nicotine has been reported to inhibit TNF-α, IL-1, and ROS production in microglia. Mitochondrial permeability transition pore (mPTP) plays an important role in neurotoxicity as well. Here, we investigated whether activating the microglial α7-nAChR has a neuroprotective role on neural stem cells (NSCs) and the function of mPTP in NSCs in this process. The expression of α7-nAChR in rat NSCs was detected by immunocytochemistry and RT-PCR. The viability of microglia and NSCs was examined by MTT assay. The mitochondrial membrane potential (ΔΨm) and morphological characteristics of NSCs was measured by JC-1 staining and transmission electron microscopy respectively. The distribution of cytochrome c in the subcellular regions of NSCs was visualized by confocal laser scanning microscopy, and the expression levels of cyclophilin D and cleaved caspase-3 were assayed by western blot. The apoptotic rate of NSCs was measured by flow cytometry. The expression of α7-nAChR was detected in microglial cells, but no expression was found in NSCs. The viability of rat microglial cells and NSCs was not affected by reagents or coculture itself. Aβ1-42-mediated microglial activation impaired the morphology and the ΔΨm of mitochondria of NSCs as well as increased cell apoptosis. However, the damage was attenuated when the α7-nAChRs on microglial cells were activated or the mPTPs on NSCs were blocked. Blockade of mPTPs on NSCs and activation of α7-nAChRs on microglia exhibit neuroprotective roles in Aβ-induced neurotoxicity of NSCs.

Overexpression of mitochondrial Hsp75 protects neural stem cells against microglia-derived soluble factor-induced neurotoxicity by regulating mitochondrial permeability transition pore opening in vitro

Microglia (MG)-induced neurotoxicity, a major determinant of Alzheimer's disease, is closely related to the survival of neural stem cells (NSCs). Heat shock protein 75 (Hsp75) has been reported to exert protective effects against environmental stresses; however, whether or not it protects NSCs against MG-derived soluble factor-induced neurotoxicity remains unclear. In the present study, we constructed NSCs that overexpressed human Hsp75 protein and established a co-culture system in order to elucidate the role of Hsp75 in NSC-MG interactions. The results obtained indicated that Hsp75 expression increased after 12 h of soluble factor induction and continued to increase for up to 36 h of treatment. The overexpression of Hsp75 decreased NSC apoptosis and preserved mitochondrial membrane potential. Further experiments revealed that the overexpression of Hsp75 inhibited the formation of cyclophilin D (CypD)-dependent mitochondrial permeability transition pore (mPTP) involvement in neurotoxicity-mediated mitochondrial dysfunction and suppressed the activation of the mitochondrial apoptotic cascade, as demonstrated by the inhibition of the release of cytochrome c (Cytc) and the activation of caspase-3. The findings of this study demonstrate that Hsp75 overexpression prevents the impairment of NSCs induced by MG-derived soluble factors by regulating the opening of mPTP. Thus, Hsp75 warrants further investigation as a potential candidate for protection against neurotoxicity.

Induction of Apoptosis and Reduction of Endogenous Glutathione Level by the Ethyl-Acetate Soluble Fraction of the Methanol Extract of the Roots of Potentilla fulgens in Cancer Cells

Potentilla fulgens root traditionally used as a folk remedy in Meghalaya, India. However, systematic evaluation of its anticancer efficacy was limited. We investigated the anticancer potentials of the various extracts prepared by partitioning of the methanol extract of the root with the aim to discover major contributing factors from the most effective fractions. Methanol extract of P. fulgens roots (PRE) was prepared by maceration which was subsequently fractionated into hexane, ethyl-acetate (EA) and n-butanol soluble fractions. Various assays (clonogenic assay, Flow cytometry analysis, western blot, semiquantitative RT-PCR and the level of endogenous glutathione) were used to evaluate different parameters, such as Cell survivability, PARP-1 proteolysis, expression pattern of anti-apoptotic and γ-glutamyl-cysteine synthetase heavy subunit (GCSC) genes in both MCF-7 and U87 cancer cell lines. Since the EA-fraction showed most efficient growth inhibitory effect, it was further purified and a total of nine compounds and some monomeric and dimeric flavan-3-ols were identified and characterized. Three compounds viz., epicatechin (EC), gallic acid (GA) and ursolic acid (UA) were taken on the basis of their higher yield and 10 μg/ml of each was mixed together. The concentration used in this study for PRE, EA- and Hex-fraction was 100 μg/ml, which was higher than the IC₅₀ value. Apoptotic cell death in the PRE, EA-fraction and EC+GA+UA treated cancer cell cultures was significantly greater than in normal cells due to suppression of anti-apoptotic protein Bcl2 following treatment. Depletion of glutathione by downregulating GCSC was also observed. Induction of apoptosis and lowering the level of glutathione are considered to be positive activity for an anticancer agent. Therefore, modulation of GSH concentration in tumor cells by PRE and its EA-fraction opened up the possibility of a new therapeutic approach because these plant products are not harmful to normal cells and may regulate the tumor cellular response to different anticancer treatments. Thus, it would be interesting to examine efficacy of these plant products or EA-fraction in human cancer treatment.

The calcium uniporter regulates the permeability transition pore in isolated cortical mitochondria

To investigate the influence of the mitochondrial calcium uniporter on the mitochondrial permeability transition pore, the present study observed mitochondrial morphology in cortical neurons isolated from adult rats using transmission electron microscopy, and confirmed the morphology and activity of isolated mitochondria by detecting succinic dehydrogenase and monoamine oxidase, two mitochondrial enzymes. Isolated mitochondria were treated with either ruthenium red, an inhibitor of the uniporter, spermine, an activator of the uniporter, or in combination with cyclosporin A, an inhibitor of the mitochondrial permeability transition pore. Results showed that ruthenium red inhibited CaCl2-induced mitochondrial permeability transition pore opening, spermine enhanced opening, and cyclosporin A attenuated the effects of spermine. Results demonstrated that the mitochondrial calcium uniporter plays a role in regulating the mitochondrial permeability transition pore in mitochondria isolated from the rat brain cortex.

Immune profiling and cancer post transplantation

Half of all long-term (> 10 year) australian kidney transplant recipients (KTR) will develop squamous cell carcinoma (SCC) or solid organ cancer (SOC), making cancer the leading cause of death with a functioning graft. At least 30% of KTR with a history of SCC or SOC will develop a subsequent SCC or SOC lesion. Pharmacological immunosuppression is a major contributor of the increased risk of cancer for KTR, with the cancer lesions themselves further adding to systemic immunosuppression and could explain, in part, these phenomena. Immune profiling includes; measuring immunosuppressive drug levels and pharmacokinetics, enumerating leucocytes and leucocyte subsets as well as testing leucocyte function in either an antigen specific or non-specific manner. Outputs can vary from assay to assay according to methods used. In this review we define the rationale behind post-transplant immune monitoring assays and focus on assays that associate and/or have the ability to predict cancer and rejection in the KTR. We find that immune monitoring can identify those KTR of developing multiple SCC lesions and provide evidence they may benefit from pharmacological immunosuppressive drug dose reductions. In these KTR risk of rejection needs to be assessed to determine if reduction of immunosuppression will not harm the graft.

Molecular mechanisms of reduced nerve toxicity by titanium dioxide nanoparticles in the phoxim-exposed brain of Bombyx mori

Bombyx mori (B. mori), silkworm, is one of the most important economic insects in the world, while phoxim, an organophosphorus (OP) pesticide, impact its economic benefits seriously. Phoxim exposure can damage the brain, fatbody, midgut and haemolymph of B. mori. However the metabolism of proteins and carbohydrates in phoxim-exposed B. mori can be improved by Titanium dioxide nanoparticles (TiO2 NPs). In this study, we explored whether TiO2 NPs treatment can reduce the phoxim-induced brain damage of the 5th larval instar of B. mori. We observed that TiO2 NPs pretreatments significantly reduced the mortality of phoxim-exposed larva and relieved severe brain damage and oxidative stress under phoxim exposure in the brain. The treatments also relieved the phoxim-induced increases in the contents of acetylcholine (Ach), glutamate (Glu) and nitric oxide (NO) and the phoxim-induced decreases in the contents of norepinephrine (NE), Dopamine (DA), and 5-hydroxytryptamine (5-HT), and reduced the inhibition of acetylcholinesterase (AChE), Na+/K+-ATPase, Ca2+-ATPase, and Ca2+/Mg2+-ATPase activities and the activation of total nitric oxide synthase (TNOS) in the brain. Furthermore, digital gene expression profile (DGE) analysis and real time quantitative PCR (qRT-PCR) assay revealed that TiO2 NPs pretreatment inhibited the up-regulated expression of ace1, cytochrome c, caspase-9, caspase-3, Bm109 and down-regulated expression of BmIap caused by phoxim; these genes are involved in nerve conduction, oxidative stress and apoptosis. TiO2 NPs pretreatment also inhibited the down-regulated expression of H+ transporting ATP synthase and vacuolar ATP synthase under phoxim exposure, which are involved in ion transport and energy metabolism. These results indicate that TiO2 NPs pretreatment reduced the phoxim-induced nerve toxicity in the brain of B. mori.

High-resolution crystal structures of two crystal forms of human cyclophilin D in complex with PEG 400 molecules

Cyclophilin D (CypD) is a key mitochondrial target for amyloid-β-induced mitochondrial and synaptic dysfunction and is considered a potential drug target for Alzheimer's disease. The high-resolution crystal structures of primitive orthorhombic (CypD-o) and primitive tetragonal (CypD-t) forms have been determined to 1.45 and 0.85 Å resolution, respectively, and are nearly identical structurally. Although an isomorphous structure of CypD-t has previously been reported, the structure reported here was determined at atomic resolution, while CypD-o represents a new crystal form for this protein. In addition, each crystal form contains a PEG 400 molecule bound to the same region along with a second PEG 400 site in CypD-t which occupies the cyclosporine A inhibitor binding site of CypD. Highly precise structural information for CypD should be extremely useful for discerning the detailed interaction of small molecules, particularly drugs and/or inhibitors, bound to CypD. The 0.85 Å resolution structure of CypD-t is the highest to date for any CypD structure.

CKMT1 regulates the mitochondrial permeability transition pore in a process that provides evidence for alternative forms of the complex

The permeability transition pore (PT-pore) mediates cell death through the dissipation of the mitochondrial membrane potential (ΔΨm). Because the exact composition of the PT-pore is controversial, it is crucial to investigate the actual molecular constituents and regulators of this complex. We found that mitochondrial creatine kinase-1 (CKMT1) is a universal and functionally necessary gatekeeper of the PT-pore, as its depletion induces mitochondrial depolarization and apoptotic cell death. This can be inhibited efficiently by bongkrekic acid, a compound that is widely used to inhibit the PT-pore. However, when the 'classical' PT-pore subunits cyclophilin D and VDAC1 are pharmacologically inhibited or their expression levels reduced, mitochondrial depolarization by CKMT1 depletion remains unaffected. At later stages of drug-induced apoptosis, CKMT1 levels are reduced, suggesting that CKMT1 downregulation acts to reinforce the commitment of cells to apoptosis. A novel high-molecular-mass CKMT1 complex that is distinct from the known CKMT1 octamer disintegrates upon treatment with cytotoxic drugs, concomitant with mitochondrial depolarization. Our study provides evidence that CKMT1 is a key regulator of the PT-pore through a complex that is distinct from the classical PT-pore.

The effects of bioactive compounds from plant foods on mitochondrial function: a focus on apoptotic mechanisms

Mitochondria are essential organelles for cellular integrity and functionality maintenance and their imparement is implicated in the development of a wide range of diseases, including metabolic, cardiovascular, degenerative and hyperproliferative pathologies. The identification of different compounds able to interact with mitochondria for therapeutic purposes is currently becoming of primary importance. Indeed, it is well known that foods, particularly those of vegetable origin, present several constituents with beneficial effects on health. This review summarizes and updates the most recent findings concerning the mechanisms through which different dietary compounds from plant foods affect mitochondria functionality in healthy and pathological in vitro and in vivo models, paying particular attention to the pathways involved in mitochondrial biogenesis and apoptosis.

No acceleration of UV-induced skin carcinogenesis from evenly spread dietary intake of cyclosporine in contrast to oral bolus dosages

BACKGROUND

Organ transplant recipients using the immunosuppressant cyclosporine have an increased risk for developing nonmelanoma skin cancer. Disparate effects of cyclosporine have, however, been reported on UV-induced skin carcinogenesis in mouse experiments. Therefore, we set out to compare three experimental protocols using mice, with the aim to emulate most closely the increased skin cancer risk in organ transplant recipients.

METHODS

UV carcinogenesis was performed in hairless SKH-1 mice by three protocols: dietary cyclosporine and daily UV exposures, dietary cyclosporine after a period of UV exposures, and bolus dosing cyclosporine by gavage and repeated UV exposures.

RESULTS

Using chronic UV exposure, continuous dietary administration of cyclosporine was shown to inhibit tumor formation. Dietary cyclosporine after a period of UV exposures did not affect ensuing UV carcinogenesis. However, in contrast with dietary cyclosporine, bolus dosages of cyclosporine by gavage, resulting in strongly varying blood levels of cyclosporine, increased tumor development in chronically UV-exposed mice. There was no difference in tumor development between mice UV-irradiated during peak or trough levels of cyclosporine in the blood. Time-averaged levels in these mice were similar to those with cyclosporine in the diet.

CONCLUSIONS

Cyclosporine in bolus doses appears to increase skin cancer development, whereas cyclosporine administration more evenly spread over time does not. Extrapolation to transplant patients suggests that the mode of administrating cyclosporine may be crucial for the increased skin cancer risk and that this risk might be lowered with a more steady release of cyclosporine in the body.

Mitochondrial dysfunction and permeability transition in osteosarcoma cells showing the Warburg effect

Metabolic reprogramming in cancer is manifested by persistent aerobic glycolysis and suppression of mitochondrial function and is known as the Warburg effect. The Warburg effect contributes to cancer progression and is considered to be a promising therapeutic target. Understanding the mechanisms used by cancer cells to suppress their mitochondria may lead to development of new approaches to reverse metabolic reprogramming. We have evaluated mitochondrial function and morphology in poorly respiring LM7 and 143B osteosarcoma (OS) cell lines showing the Warburg effect in comparison with actively respiring Saos2 and HOS OS cells and noncancerous osteoblastic hFOB cells. In LM7 and 143B cells, we detected markers of the mitochondrial permeability transition (MPT), such as mitochondrial swelling, depolarization, and membrane permeabilization. In addition, we detected mitochondrial swelling in human OS xenografts in mice and archival human OS specimens using electron microscopy. The MPT inhibitor sanglifehrin A reversed MPT markers and increased respiration in LM7 and 143B cells. Our data suggest that the MPT may play a role in suppression of mitochondrial function, contributing to the Warburg effect in cancer.

The mitochondria-mediate apoptosis of Lepidopteran cells induced by azadirachtin

Mitochondria have been shown to play an important role in apoptosis using mammalian cell lines. However, this seems not to be the case in Drosophila, an insect model organism; thus more in-depth studies of insect cell apoptosis are necessary. In the present study, mitochondrial involvement during azadirachtin- and camptothecin-induced apoptosis in Spodoptera frugiperda Sf9 cells (isolated from Spodoptera frugiperda pupal ovarian tissue) was investigated. The results showed that both azadirachtin and camptothecin could induce apoptosis in Sf9 cells. Reactive oxygen species (ROS) generation, activation of mitochondrial permeability transition pores (MPTPs) and loss of mitochondrial membrane potential (MMP) were observed very early during apoptosis and were followed subsequently by the release of cytochrome-c from the mitochondria. Furthermore, the results also revealed that the opening of MPTPs and the loss of MMP induced by azadirachtin could be significantly inhibited by the permeability transition pore (PTP) inhibitor cyclosporin A (CsA), which was used to identify the key role of mitochondria in the apoptosis of Sf9 cells. However, in camptothecin-treated Sf9 cells, CsA could not suppress the opening of MPTPs and the loss of MMP when apoptosis was induced. The data from caspase-3 and caspase-9 activity assays and detection of apoptosis by morphological observation and flow cytometry also uncovered the different effect of CsA on the two botanical apoptosis inducers. Although different mechanisms of apoptosis induction exist, our study revealed that mitochondria play a crucial role in insect cell line apoptosis.

Oxidative stress modulates mitochondrial failure and cyclophilin D function in X-linked adrenoleukodystrophy

A common process associated with oxidative stress and severe mitochondrial impairment is the opening of the mitochondrial permeability transition pore, as described in many neurodegenerative diseases. Thus, inhibition of mitochondrial permeability transition pore opening represents a potential target for inhibiting mitochondrial-driven cell death. Among the mitochondrial permeability transition pore components, cyclophilin D is the most studied and has been found increased under pathological conditions. Here, we have used in vitro and in vivo models of X-linked adrenoleukodystrophy to investigate the relationship between the mitochondrial permeability transition pore opening and redox homeostasis. X-linked adrenoleukodystrophy is a neurodegenerative condition caused by loss of function of the peroxisomal ABCD1 transporter, in which oxidative stress plays a pivotal role. In this study, we provide evidence of impaired mitochondrial metabolism in a peroxisomal disease, as fibroblasts in patients with X-linked adrenoleukodystrophy cannot survive when forced to rely on mitochondrial energy production, i.e. on incubation in galactose. Oxidative stress induced under galactose conditions leads to mitochondrial damage in the form of mitochondrial inner membrane potential dissipation, ATP drop and necrotic cell death, together with increased levels of oxidative modifications in cyclophilin D protein. Moreover, we show increased expression levels of cyclophilin D in the affected zones of brains in patients with adrenomyeloneuropathy, in spinal cord of a mouse model of X-linked adrenoleukodystrophy (Abcd1-null mice) and in fibroblasts from patients with X-linked adrenoleukodystrophy. Notably, treatment with antioxidants rescues mitochondrial damage markers in fibroblasts from patients with X-linked adrenoleukodystrophy, including cyclophilin D oxidative modifications, and reverses cyclophilin D induction in vitro and in vivo. These findings provide mechanistic insight into the beneficial effects of antioxidants in neurodegenerative and non-neurodegenerative cyclophilin D-dependent disorders.

Melatonin protects against isoproterenol-induced alterations in cardiac mitochondrial energy-metabolizing enzymes, apoptotic proteins, and assists in complete recovery from myocardial injury in rats

The present study was undertaken to explore the protective effect of melatonin against isoproterenol bitartrate (ISO)-induced rat myocardial injury and to test whether melatonin has a role in preventing myocardial injury and recovery when the ISO-induced stress is withdrawn. Treatment for rats with ISO altered the activities of some of the key mitochondrial enzymes related to energy metabolism, the levels of some stress proteins, and the proteins related to apoptosis. These changes were found to be ameliorated when the animals were pretreated with melatonin at a dose of 10 mg/kg BW, i.p. In addition to its ability to reduce ISO-induced mitochondrial dysfunction, we also studied the role of melatonin in the recovery of the cardiac tissue after ISO-induced damage. Continuation of melatonin treatment in rats after the withdrawal of ISO treatment was found to reduce the activities of cardiac injury biomarkers including serum glutamate oxaloacetate transaminase (SGOT), lactate dehydrogenase (LDH), and cardio-specific LDH1 to control levels. The levels of tissue lipid peroxidation and reduced glutathione were also brought back to that seen in control animals by continued melatonin treatment. Continuation of melatonin treatment in post-ISO treatment period was also found to improve cardiac tissue morphology and heart function. Thus, the findings indicate melatonin’s ability to provide cardio protection at a low pharmacological dose and its role in the recovery process. Melatonin, a molecule with very low or no toxicity may be considered as a therapeutic for the treatment for ischemic heart disease.

Peroxisome proliferator-activated receptor γ coactivator1- gene α transfer restores mitochondrial biomass and improves mitochondrial calcium handling in post-necrotic mdx mouse skeletal muscle

Alterations of mitochondrial function have been implicated in the pathogenesis of Duchenne muscular dystrophy. In the present study, mitochondrial respiratory function, reactive oxygen species (ROS) dynamics and susceptibility to Ca(2+)-induced permeability transition pore (PTP) opening were investigated in permeabilized skeletal muscle fibres of 6-week-old mdx mice, in order to characterize the magnitude and nature of mitochondrial dysfunction at an early post-necrotic stage of the disease. Short-term overexpression of the transcriptional co-activator PGC1α, achieved by in vivo plasmid transfection, was then performed to determine whether this intervention could prevent mitochondrial impairment and mitigate associated biochemical abnormalities. Compared with normal mice, mdx mice exhibited a lower mitochondrial biomass and oxidative capacity, greater ROS buffering capabilities, and an increased vulnerability to Ca(2+)-induced opening of the mitochondrial permeability transition pore complex. PGC1α gene transfer restored mitochondrial biomass, normalized the susceptibility to PTP opening and increased the capacity of mitochondria to buffer Ca(2+)(.) This was associated with reductions in the activity levels of the Ca(2+)-dependent protease calpain as well as caspases 3 and 9. Overall, these results suggest that overexpression of PGC1α in dystrophin-deficient muscles, after the onset of necrosis, has direct beneficial effects upon multiple aspects of mitochondrial function, which may in turn mitigate the activation of proteolytic and apoptotic signalling pathways associated with disease progression.

Central roles of apoptotic proteins in mitochondrial function

Mitochondria have been classically characterized as organelles with responsibility for cellular energy production in the form of ATP, but they are also the organelles through which apoptotic signaling occurs. Cell stress stimuli can result in outer membrane permeabilization, after which mitochondria release numerous proteins involved in apoptotic signaling, including cytochrome c, apoptosis-inducing factor, endonuclease G, Smac/DIABLO and Omi/HtrA2. Cell fate is determined by signaling through apoptotic proteins within the Bcl-2 (B-cell lymphoma 2) protein family, which converges on mitochondria. Many cancerous cells display abnormal levels of Bcl-2 protein family member expression that results in defective apoptotic signaling. Alterations in bioenergetic function also contribute to cancer as well as numerous other disorders. Recent evidence indicates that several pro-apoptotic proteins localized within mitochondria, as well as proteins within the Bcl-2 protein family, can influence mitochondrial bioenergetic function. This review focuses on the emerging roles of these proteins in the control of mitochondrial activity.

Proteomic analysis of male zebrafish livers chronically exposed to perfluorononanoic acid

Perfluorononanoic acid (PFNA), a synthetic perfluorinated carboxylic acid and fluorosurfactant, is a known environmental contaminant found in people and wildlife. To understand the hepatotoxicity mechanism of PFNA, male zebrafish (n=200) were exposed to differing concentrations of PFNA (0, 0.1, 0.5, and 1.0 mg/L) for 180 days. A two-dimensional difference gel electrophoresis (2-D DIGE) approach coupled with MALDI-TOF-MS/MS analysis was employed to detect and identify the differential expressed proteins. A total of 57 proteins were successfully identified and categorized into functional classes that included metabolism (amino acid metabolism, TCA cycle and pyruvate metabolism, gluconeogenesis and glycolysis, protein metabolism and modification, and nucleotides metabolism), structure and motility, stress and defense, signal transduction, and cell communication. Our proteomic analyses added new perspective to PFNA hepatotoxicity in zebrafish. Results regarding mRNA levels demonstrated that the involvement of peroxisome proliferator-activated receptors (PPARs) could not sufficiently explain the hepatotoxicity mechanism of PFAAs in zebrafish. The extensive protein variations indicated that multiple cellular pathways were involved in and suggested that multiple protein molecules should be simultaneously targeted as an effective strategy to counter PFNA toxicity. Other potential modes should be further investigated.

Mitochondrial function and dysfunction: an update

With the current explosion of knowledge on the role of mitochondrial dysfunction in the genesis of various human disease states, there is an increased interest in targeting mitochondrial processes, pathways, and proteins for drug discovery efforts in cancer and cardiovascular, metabolic, and central nervous system diseases, the latter including autism and neurodegenerative diseases. We provide an update on understanding the central role of the mitochondrion in ATP and reactive oxygen species production and in controlling cell death pathways.

A novel copper complex induces paraptosis in colon cancer cells via the activation of ER stress signalling

Platinum anticancer drugs have been used for three decades despite their serious side effects and the emerging of resistance phenomena. Recently, a phosphine copper(I) complex, [Cu(thp)₄][PF₆] (CP), gained special attention because of its strong antiproliferative effects. CP killed human colon cancer cells more efficiently than cisplatin and oxaliplatin and it overcame platinum drug resistance. CP preferentially reduced cancer cell viability whereas non-tumour cells were poorly affected. Colon cancer cells died via a programmed cell death whose transduction pathways were characterized by the absence of hallmarks of apoptosis. The inhibition of 26S proteasome activities induced by CP caused intracellular accumulation of polyubiquitinated proteins and the functional suppression of the ubiquitin–proteasome pathway thus triggering endoplasmic reticulum stress. These data, providing a mechanistic characterization of CP-induced cancer cell death, shed light on the signaling pathways involved in paraptosis thus offering a new tool to overcome apoptosis-resistance in colon cancer cells.

Anesthetics isoflurane and desflurane differently affect mitochondrial function, learning, and memory

OBJECTIVE

There are approximately 8.5 million Alzheimer disease (AD) patients who need anesthesia and surgery care every year. The inhalation anesthetic isoflurane, but not desflurane, has been shown to induce caspase activation and apoptosis, which are part of AD neuropathogenesis, through the mitochondria-dependent apoptosis pathway. However, the in vivo relevance, underlying mechanisms, and functional consequences of these findings remain largely to be determined.

METHODS

We therefore set out to assess the effects of isoflurane and desflurane on mitochondrial function, cytotoxicity, learning, and memory using flow cytometry, confocal microscopy, Western blot analysis, immunocytochemistry, and the fear conditioning test.

RESULTS

Here we show that isoflurane, but not desflurane, induces opening of mitochondrial permeability transition pore (mPTP), increase in levels of reactive oxygen species, reduction in levels of mitochondrial membrane potential and adenosine-5'-triphosphate, activation of caspase 3, and impairment of learning and memory in cultured cells, mouse hippocampus neurons, mouse hippocampus, and mice. Moreover, cyclosporine A, a blocker of mPTP opening, attenuates isoflurane-induced mPTP opening, caspase 3 activation, and impairment of learning and memory. Finally, isoflurane may induce the opening of mPTP via increasing levels of reactive oxygen species.

INTERPRETATION

These findings suggest that desflurane could be a safer anesthetic for AD patients as compared to isoflurane, and elucidate the potential mitochondria-associated underlying mechanisms, and therefore have implications for use of anesthetics in AD patients, pending human study confirmation.