The mitochondrion in apoptosis: how Pandora's box opens

Mitochondria and Critical Illness

Classically, mitochondria have largely been believed to influence the development of illness by modulating cell metabolism and determining the rate of production of high-energy phosphate compounds (eg, adenosine triphosphate). It is now recognized that this view is simplistic and that mitochondria play key roles in many other processes, including cell signaling, regulating gene expression, modulating cellular calcium levels, and influencing the activation of cell death pathways (eg, caspase activation). Moreover, these multiple mitochondrial functional characteristics are now known to influence the evolution of cellular and organ function in many disease states, including sepsis, ICU-acquired skeletal muscle dysfunction, acute lung injury, acute renal failure, and critical illness-related immune function dysregulation. In addition, diseased mitochondria generate toxic compounds, most notably released mitochondrial DNA, which can act as danger-associated molecular patterns to induce systemic toxicity and damage multiple organs throughout the body. This article reviews these evolving concepts relating mitochondrial function and acute illness. The discussion is organized into four sections: (1) basics of mitochondrial physiology; (2) cellular mechanisms of mitochondrial pathophysiology; (3) critical care disease processes whose initiation and evolution are shaped by mitochondrial pathophysiology; and (4) emerging treatments for mitochondrial dysfunction in critical illness.

EPA and DHA can modulate cell death via inhibition of the Fas/tBid-mediated signaling pathway with ISKNV infection in grouper fin cell line (GF-1) cells

Polyunsaturated fatty acids (PUFAs) play important roles in organisms, including the structure and liquidity of cell membranes, anti-oxidation and anti-inflammation. Very little has been done in terms of the effect of PUFAs on cell death, especially on DNA virus. In this study, we demonstrated that the infectious spleen and kidney necrosis virus (ISKNV) can induce host cell death via the apoptotic cell death pathway, which correlated to modulation by PUFAs in grouper fin cell line (GF-1) cells. We screened the PUFAs, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), for the ability of different dosages to prevent cell death in GF-1 cells with ISKNV infection. In the results, each 10 μM of DHA and EPA treatment enhanced host cell viability up to 80% at day 5 post-infection. Then, in Terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) assay, DHA- and EPA-treated groups reduced TUNEL positive signals 50% in GF-1 cells with ISKNV infection. Then, through studies of the mechanism of cell death, we found that ISKNV can induce both the Bax/caspase-3 and Fas/caspase-8/tBid death signaling pathways in GF-1 cells, especially at day 5 post-infection. Furthermore, we found that DHA and EPA treatment can either prevent caspase-3 activation on 17-kDa form cleavage or Bid cleaved (15-kDa form) for activation by caspase-8, apparently. On the other hand, the anti-apoptotic gene Bcl-2 was upregulated 0.3-fold and 0.15-fold at day 3 and day 5, respectively, compared to ISKNV-infected and DHA-treated cells; that this did not happen in the EPA-treated group showed that different PUFAs trigger different signals. Finally, ISKNV-infected GF-1 cells treated with either DHA or EPA showed a 5-fold difference in viral titer at day 5. Taken together, these results suggest that optimal PUFA treatment can affect cell death signaling through both the intrinsic and extrinsic death pathways, reducing viral expression and viral titer in GF-1 cells. This finding may provide insight in DNA virus infection and control.

Rational design and action mechanisms of chemically innovative organoselenium in cancer therapy

Organo-seleno compounds (org-Se) have been widely used in antitumor, antiviral, and antiinflammatory therapy; antioxidation and other biological fields. As such, they have made an important contribution to overcoming various kinds of diseases, and researchers are increasingly attracted to org-Se's synthesis and functional design. This review is mainly focused on the design and synthesis of various kinds of org-Se, followed by their anticancer mechanisms such as the mitochondria mediated pathway induced by ROS, death receptor mediated pathways involving p53 phosphorylation, and the activation of the AMPK pathway to promote apoptosis. Org-Se also serves as a sensitizer in chemotherapy and radiotherapy, and an antagonist against the cytotoxic effects induced by chemotherapeutic agents. Finally, we will summarize the development of cancer-targeted org-Se containing complexes, and nanotechnology-based org-Se for anticancer application. This review could provide information for the future design of chemically innovative org-Se with anticancer potential, and shed light on the discovery of nanomaterial-based pharmaceuticals to improve drug development and formation.

Neochamaejasmin A Induces Mitochondrial-Mediated Apoptosis in Human Hepatoma Cells via ROS-Dependent Activation of the ERK1/2/JNK Signaling Pathway

The botanical constituents of Stellera chamaejasme Linn. exhibit various pharmacological and medicinal activities. Neochamaejasmin A (NCA), one main active constituent of S. chamaejasme, inhibits cell proliferation and induces cell apoptosis in several types of tumor cells. However, the antitumor effect of NCA on hepatocellular carcinoma cells is still unclear. In this study, NCA (36.9, 73.7, and 147.5 μM) significantly inhibited hepatoblastoma-derived HepG2 cell proliferation in a concentration-dependent manner. Hoechst 33258 staining and flow cytometry showed that apoptotic morphological changes were observed and the apoptotic rate was significantly increased in NCA-treated HepG2 cells, respectively. Additionally, the levels of Bax, cleaved caspase-3, and cytoplasmic cytochrome c were increased, while the level of Bcl-2 was decreased in NCA-treated HepG2 cells when compared with the control group. Moreover, we found that the reactive oxygen species (ROS) level was significantly higher and the mitochondrial membrane potential was remarkably lower in NCA-treated HepG2 cells than in the control group. Further studies demonstrated that the levels of p-JNK and p-ERK1/2 were significantly upregulated in NCA-treated HepG2 cells, and pretreatment with JNK and ERK1/2 inhibitors, SP600125 and PD0325901, respectively, suppressed NCA-induced cell apoptosis of HepG2 cells. In addition, NCA also significantly inhibited human hepatoma BEL-7402 cell proliferation and induced cell apoptosis through the ROS-mediated mitochondrial apoptotic pathway. These results implied that NCA induced mitochondrial-mediated cell apoptosis via ROS-dependent activation of the ERK1/2/JNK signaling pathway in HepG2 cells.

FAD/NADH Dependent Oxidoreductases: From Different Amino Acid Sequences to Similar Protein Shapes for Playing an Ancient Function

Flavoprotein oxidoreductases are members of a large protein family of specialized dehydrogenases, which include type II NADH dehydrogenase, pyridine nucleotide-disulphide oxidoreductases, ferredoxin-NAD+ reductases, NADH oxidases, and NADH peroxidases, playing a crucial role in the metabolism of several prokaryotes and eukaryotes. Although several studies have been performed on single members or protein subgroups of flavoprotein oxidoreductases, a comprehensive analysis on structure-function relationships among the different members and subgroups of this great dehydrogenase family is still missing. Here, we present a structural comparative analysis showing that the investigated flavoprotein oxidoreductases have a highly similar overall structure, although the investigated dehydrogenases are quite different in functional annotations and global amino acid composition. The different functional annotation is ascribed to their participation in species-specific metabolic pathways based on the same biochemical reaction, i.e., the oxidation of specific cofactors, like NADH and FADH₂. Notably, the performed comparative analysis sheds light on conserved sequence features that reflect very similar oxidation mechanisms, conserved among flavoprotein oxidoreductases belonging to phylogenetically distant species, as the bacterial type II NADH dehydrogenases and the mammalian apoptosis-inducing factor protein, until now retained as unique protein entities in Bacteria/Fungi or Animals, respectively. Furthermore, the presented computational analyses will allow consideration of FAD/NADH oxidoreductases as a possible target of new small molecules to be used as modulators of mitochondrial respiration for patients affected by rare diseases or cancer showing mitochondrial dysfunction, or antibiotics for treating bacterial/fungal/protista infections.

Dichloroacetate (DCA) and Cancer: An Overview towards Clinical Applications

An extensive body of literature describes anticancer property of dichloroacetate (DCA), but its effective clinical administration in cancer therapy is still limited to clinical trials. The occurrence of side effects such as neurotoxicity as well as the suspicion of DCA carcinogenicity still restricts the clinical use of DCA. However, in the last years, the number of reports supporting DCA employment against cancer increased also because of the great interest in targeting metabolism of tumour cells. Dissecting DCA mechanism of action helped to understand the bases of its selective efficacy against cancer cells. A successful coadministration of DCA with conventional chemotherapy, radiotherapy, other drugs, or natural compounds has been tested in several cancer models. New drug delivery systems and multiaction compounds containing DCA and other drugs seem to ameliorate bioavailability and appear more efficient thanks to a synergistic action of multiple agents. The spread of reports supporting the efficiency of DCA in cancer therapy has prompted additional studies that let to find other potential molecular targets of DCA. Interestingly, DCA could significantly affect cancer stem cell fraction and contribute to cancer eradication. Collectively, these findings provide a strong rationale towards novel clinical translational studies of DCA in cancer therapy.

Liver mitochondrial membrane permeability modulation in insulin-resistant, uninephrectomised male rats by Clerodendrum volubile P. Beauv and Manihot esculenta Crantz

Background

Non-alcoholic fatty liver disease, which occurs in people who are not alcohol drinkers, describes some of the pathogenic conditions that may be in the least characterized by simple steatosis or can be as serious as non-alcoholic steatohepatitis and cirrhosis. Its mechanistic pathogenesis has been said to arise from insulin resistance and oxidative stress, which may be compounded by obesity. An experimental model showing, systemic insulin resistance, obesity and accumulated hepatic fatty acids was created in adult male rats using high-fat diet manipulation and surgical removal of the left kidney (uninephrectomy). This study sought to identify the impact of these multiple burdens on the liver mitochondrial membrane permeability transition pore opening, and the possible in vitro effects of the extracts ofClerodendrum volubileandManihot esculentaleaves on the membrane permeabilization.

Results

The results indicated that the methanolic extract ofClerodendrum volubileleaf inhibited mitochondrial membrane pore opening in the insulin resistance condition or when it is followed by uni-nephrectomy, while the ethanolic extract ofManihot esculentaleaf does the same in the insulin resistance condition both prior to and following uni-nephrectomy.

Conclusion

Since the vegetable extracts were able to abrogate mitochondrial pore opening at low concentrations, the structural integrity of the mitochondria can possibly be restored over time if treated by the vegetable extracts. Research efforts should, therefore, be made to harness the drugability of the bioactives of these vegetables for use in the treatment of non-alcoholic fatty liver disease arising from insulin resistance and renal failure.

p53-Dependent pathway and the opening of mPTP mediate the apoptosis of co-cultured Sertoli-germ cells induced by microcystin-LR

Microcystin-LR (MC-LR), a potent endotoxin, can induce reproductive toxicity. In order to investigate the role and mechanisms of apoptosis (p53-dependent and mitochondrial pathways) of germ cells induced by MC-LR, the co-cultured primary Sertoli-germ cells from Sprague-Dawley rats were used for the experiments. Expression levels of proteins, genes, and mitochondrial membrane potential (MMP) were obtained after exposing co-cultured Sertoli-germ cells to MC-LR with or without the addition of the p53 inhibitor, pifithrin-α (PFT-α), and MMP inhibitor, cyclosporin A (CsA). Results indicated that MC-LR could activate p53-dependent pathway-associated proteins in Sertoli-germ cells, leading to a decrease in MMP (indicating the opening of mitochondrial permeability transition pore [mPTP] and the release of Cytochrome-c [Cyt-c]) from the mitochondria into the cytoplasm and eventually the induction of apoptosis. PFT-α inhibited the expression ofp53, ameliorated the MMP of the co-cultured Sertoli-germ cells, and prevented the release of Cyt-c from the mitochondria into the cytoplasm, which reduces the occurrence of apoptosis. Similarly, the decreased release of Cyt-c from the mitochondria into the cytoplasm and the declined level of apoptosis in Sertoli-germ cells induced by MC-LR were observed after the addition of CsA. These results indicated that the apoptosis of the co-cultured Sertoli-germ cells induced by MC-LR was mediated by the p53-dependent pathway, with the involvement of the opening of mPTP.

Zinc causes the death of hypoxic astrocytes by inducing ROS production through mitochondria dysfunction

Cerebral ischemia triggers a cascade of events that contribute to ischemic brain damages. Zinc release and accumulation has been shown to lead to brain cell death following cerebral ischemia. However, the mechanism underlying remains to be elucidated. Our recently published work showed that suppression of mitochondrial-derived reactive oxygen species (ROS) production significantly reduced ischemic stroke related brain damage within 6 h. Herein, we investigated the relationship between zinc accumulation and mitochondrial-derived ROS production in astrocytes after 3-h hypoxia. We found that inhibition of mitochondrial-derived ROS significantly decreased total amount of ROS generation and cell death in primary astrocytes during hypoxia when zinc was overload. In contrast, the inhibition of NADPH oxidase-derived ROS had less of an effect. Our results also showed that zinc and mitochondria were colocalized in hypoxic astrocytes. Moreover, extracellular zinc addition caused zinc accumulation in the mitochondria and decreased mitochondrial membrane potential, leading to mitochondria dysfunction. These findings provide a novel mechanism that zinc accumulation contributes to hypoxia-induced astrocytes death by disrupting mitochondria function, following cerebral ischemia.

Tiger frog virus ORF104R interacts with cellular VDAC2 to inhibit cell apoptosis

Ranaviruses belong to the family Iridoviridae, and have become a serious threat to both farmed and natural populations of fish and amphibians. Previous reports showed that ranaviruses could encode viral Bcl-2 family-like proteins (vBcl-2), which play a critical role in the regulation of cell apoptosis. However, the mechanism of ranaviruses vBcl-2 interactions with host protein in mediating apoptosis remains unknown. Tiger frog virus (TFV) belonging to the genus Ranavirus has been isolated from infected tadpoles of Rana tigrina rugulosa, and it causes a high mortality rate among tiger frog tadpoles cultured in southern China. This study elucidated the molecular mechanism underlying the interaction of TFV ORF104R with the VDAC2 protein to regulate cell apoptosis. TFV ORF104R is highly similar to other ranaviruses vBcl-2 and host Mcl-1 proteins, indicating that TFV ORF104R is a postulate vBcl-2 protein. Transcription and protein expression levels showed that TFV orf104r was a late viral gene. Western blot results suggested that TFV ORF104R was a viral structural protein. Subcellular localization analysis indicated that TFV ORF104R was predominantly colocalized with the mitochondria. Overexpressed TFV ORF104R could suppress the release of cytochrome C and the activities of caspase-9 and caspase-3. These results indicated that TFV ORF104R might play an important role in anti-apoptosis. Furthermore, the interaction between TFV ORF104R and VDAC2 was detected by co-immunoprecipitation in vitro. The above observations suggest that the molecular mechanism of TFV-regulated anti-apoptosis is through the interaction of TFV ORF104R with the VDAC2 protein. Our study provided a mechanistic basis for the ranaviruses vBcl-2-mediated inhibition of apoptosis and improved the understanding on how TFV subverts host defense mechanisms in vivo.

Radiation-induced heart disease: a review of classification, mechanism and prevention

With the increasing incidence of thoracic tumors, radiation therapy (RT) has become an important component of comprehensive treatment. RT improves survival in many cancers, but it involves some inevitable complications. Radiation-induced heart disease (RIHD) is one of the most serious complications. RIHD comprises a spectrum of heart disease including cardiomyopathy, pericarditis, coronary artery disease, valvular heart disease and conduction system abnormalities. There are numerous clinical manifestations of RIHD, such as chest pain, palpitation, and dyspnea, even without obvious symptoms. Based on previous studies, the pathogenesis of RIHD is related to the production and effects of various cytokines caused by endothelial injury, inflammatory response, and oxidative stress (OS). Therefore, it is of great importance for clinicians to identify the mechanism and propose interventions for the prevention of RIHD.

Olesoxime in neurodegenerative diseases: Scrutinising a promising drug candidate

Over the last years, the experimental compound olesoxime, a mitochondria-targeting cholesterol derivative, has emerged as a promising drug candidate for neurodegenerative diseases. Numerous preclinical studies have successfully proved olesoxime's neuroprotective properties in cell and animal models of clinical conditions such as amyotrophic lateral sclerosis, Huntington disease, Parkinson disease, peripheral neuropathy and spinal muscular atrophy. The beneficial effects were attributed to olesoxime's potential impact on oxidative stress, mitochondrial permeability transition or cholesterol homoeostasis. Although no significant benefits have been demonstrated in patients of amyotrophic lateral sclerosis, and only the first 12 months of a phase II/III clinical trial showed an improvement in motor symptoms of spinal muscular atrophy, this orphan drug may still offer undiscovered potential in the treatment of neurological diseases. In our earlier preclinical studies, we demonstrated that administration of olesoxime in mouse and rat models of Huntington disease improved psychiatric and molecular phenotypes. Aside from stabilising mitochondrial function, the drug reduced the overactivation of calpains, a class of calcium-dependent proteases entangled in neurodegenerative conditions. This observation may be credited to olesoxime's action on calcium dyshomeostasis, a further hallmark in neurodegeneration, and linked to its targets TSPO and VDAC, two proteins of the outer mitochondrial membrane associated with mitochondrial calcium handling. Further research into the mode of action of olesoxime under pathological conditions, including its effect on neuronal calcium homeostasis, may strengthen the untapped potential of olesoxime or other similar compounds as a therapeutic for neurodegenerative diseases.

Aspectos generales del transporte de colesterol en la esteroidogénesis de la placenta humana

La placenta humana requiere de colesterol para sintetizar la progesterona que mantiene la relación entre el feto y la madre, lo que le permite concluir de manera exitosa el embarazo. La placenta incorpora el colesterol principalmente a través de las lipoproteínas de baja densidad (LDL) que se obtienen del torrente circulatorio materno por un mecanismo de endocitosis. A los endosomas que se generan en este proceso se les unen varias proteínas conformando los endosomas tardíos, que degradan las LDL y liberan el colesterol a las mitocondrias del sinciciotrofoblasto que lo transforman en pregnenolona y posteriormente en progesterona. Las proteínas de fusión de membranas denominados complejos SNARE participan en la liberación del colesterol en sitios de contacto específicos en donde se localizan las proteínas mitocondriales responsables de la esteroidogénesis.

Effect of dehydroepiandrosterone on the immune function of mice in vivo and in vitro

Dehydroepiandrosterone (DHEA) has anti-inflammatory, anti-oxidant and immune-regulating properties, while the mechanism of DHEA actions remains unclear. The present study aims to investigate the effect and possible mechanism of DHEA on immune function of mice in vivo and in vitro. In vivo, a lipopolysaccharide (LPS)-induced experimental inflammation model was constructed to analyze the regulation of DHEA on anti-oxidative and immune function in ICR mice; In vitro, the effects of DHEA on the biological functions of lymphocytes and macrophages were studied. The results showed that DHEA increased the activity of total antioxidant capacity and superoxide dismutase, while it decreased the level of reactive oxygen species in LPS-induced mice. Meanwhile, DHEA increased the proportion of T lymphocytes and decreased that of B lymphocytes in primary cultured spleen lymphocytes, and markedly enhanced the Th1/Th2 ratio in spleen T lymphocytes. Furthermore, DHEA significantly increased the Th1 type cytokine (IL-2 and IFN-α) and decreased the Th2 type cytokine (IL-4 and IL-10) levels in LPS-induced mice or in primary cultured spleen T lymphocytes. In addition, DHEA improved the phagocytic ability, enhanced the NO production and increased the iNOS activity in peritoneal macrophages. Our data indicates that DHEA increases the macrophages function via improving NO content and up-regulating TNF-α expression levels; and it evoked a Th1 immuno-response and repressed a Th2 immuno-response through promoting a shift in Th1/Th2 balance toward Th1-dominant immunity in vivo and in vitro. These results provide substantial evidence on the mechanism of DHEA-mediated immune function and the efficient protection against infectious and inflammatory response in animals and humans.

Toxicity and multigenerational effects of bisphenol S exposure to Caenorhabditis elegans on developmental, biochemical, reproductive and oxidative stress

Bisphenol A (BPA) is a typical endocrine disruptor. Bisphenol S (BPS) has been widely used as a substitute for various plastic materials due to the limited application of BPA. However, it does not mean that BPS is a safe substitute due to the lack of effective evaluation of BPS. In this study, the clinical model of Caenorhabditis elegans (C. elegans) was used to study the effects of BPS on the locomotion behavior, growth, reproduction, lifespan and antioxidant system. Our study found that C. elegans exposed to 0.01 μM BPS could have significantly inhibited locomotion behavior and growth, as well as damaged reproductive and antioxidant systems and lifespan. It is interesting to note that in multi-generational exposure studies, we found that BPS exhibits complex genotoxicity. With the transmission to the offspring, BPS showed more significant inhibition of the head thrashes of the nematode, while the effect on the body bends and body length was gradually weakened. The effect of BPS on the brood size shows different rules according to different concentrations and offsprings. Therefore, the safety of BPS still needs further evaluation, especially the multi-generational genotoxicity.

Mitochondrial dysfunction and chronic lung disease

The functions of body gradually decrease as the age increases, leading to a higher frequency of incidence of age-related diseases. Diseases associated with aging in the respiratory system include chronic obstructive pulmonary disease (COPD), IPF (idiopathic pulmonary fibrosis), asthma, lung cancer, and so on. The mitochondrial dysfunction is not only a sign of aging, but also is a disease trigger. This article aims to explain mitochondrial dysfunction as an aging marker, and its role in aging diseases of lung. We also discuss whether the mitochondria can be used as a target for the treatment of aging lung disease.

An anti-cancerous protein fraction from Withania somnifera induces ROS-dependent mitochondria-mediated apoptosis in human MDA-MB-231 breast cancer cells

Withania somnifera exhibits different pharmacological activities which mainly stem from its broad range of bioactive molecules. Majority of these bioactive molecules, fall into the groupings of alkaloids, steroidal lactones, phenolic compounds and glycoproteins. In this study, we evaluated a novel protein fraction, named here as WSPF, isolated from Withania somnifera roots for its cytotoxic properties against various human cancer cell lines. WSPF exhibited apoptotic activity for each cancer cell line tested, demonstrating significant activity against MDA-MB-231 human breast cancer cells with an IC₅₀ value of 92 μg/mL. WSPF induced mitochondrial-mediated apoptosis of MDA-MB-231 cells via extensive reactive oxygen species generation, dysregulation of Bax/Bcl-2, loss of mitochondrial membrane potential and caspase-3 activation. Additionally, we observed G2/M-phase cell cycle arrest, cleavage of nuclear lamin A/C proteins, and nuclear morphological changes. The present results highlight the anti-cancer properties of WSPF, indicating that the proteins in this fraction can be potential therapeutic agents for triple negative breast cancer treatment.

Mitochondrial Dysfunction and Multiple Sclerosis

In recent years, several studies have examined the potential associations between mitochondrial dysfunction and neurodegenerative diseases such as multiple sclerosis (MS), Parkinson’s disease and Alzheimer’s disease. In MS, neurological disability results from inflammation, demyelination, and ultimately, axonal damage within the central nervous system. The sustained inflammatory phase of the disease leads to ion channel changes and chronic oxidative stress. Several independent investigations have demonstrated mitochondrial respiratory chain deficiency in MS, as well as abnormalities in mitochondrial transport. These processes create an energy imbalance and contribute to a parallel process of progressive neurodegeneration and irreversible disability. The potential roles of mitochondria in neurodegeneration are reviewed. An overview of mitochondrial diseases that may overlap with MS are also discussed, as well as possible therapeutic targets for the treatment of MS and other neurodegenerative conditions.

The Mitochondrial Permeability Transition in Mitochondrial Disorders

Mitochondrial permeability transition pore (PTP), a (patho)physiological phenomenon discovered over 40 years ago, is still not completely understood. PTP activation results in a formation of a nonspecific channel within the inner mitochondrial membrane with an exclusion size of 1.5 kDa. PTP openings can be transient and are thought to serve a physiological role to allow quick Ca2+ release and/or metabolite exchange between mitochondrial matrix and cytosol or long-lasting openings that are associated with pathological conditions. While matrix Ca2+ and oxidative stress are crucial in its activation, the consequence of prolonged PTP opening is dissipation of the inner mitochondrial membrane potential, cessation of ATP synthesis, bioenergetic crisis, and cell death-a primary characteristic of mitochondrial disorders. PTP involvement in mitochondrial and cellular demise in a variety of disease paradigms has been long appreciated, yet the exact molecular entity of the PTP and the development of potent and specific PTP inhibitors remain areas of active investigation. In this review, we will (i) summarize recent advances made in elucidating the molecular nature of the PTP focusing on evidence pointing to mitochondrial FoF1-ATP synthase, (ii) summarize studies aimed at discovering novel PTP inhibitors, and (iii) review data supporting compromised PTP activity in specific mitochondrial diseases.

Differently Tagged Probes for Protein Profiling of Mitochondria

The mitochondrion is one of the most important organelles in the eukaryotic cell. Characterization of the mitochondrial proteome is a prerequisite for understanding its cellular functions at the molecular level. Here we report a proteomics method based on mitochondrion-targeting groups and click chemistry. In our strategy, three different mitochondrion-targeting moieties were each augmented with a clickable handle and a cysteine-reactive group. Fluorescence-based bioimaging and fractionation experiments clearly showed that most signals arising from the labels were localized in the mitochondria of cells, as a result of covalent attachment between probe and target proteins. The three probes had distinct profiling characteristics. Furthermore, we successfully identified more than two hundred mitochondrial proteins. The results showed that different mitochondrion-targeting groups targeted distinct proteins with partial overlap. Most of the labeled proteins were localized in the mitochondrial matrix and inner mitochondrial membrane. Our results provide a tool for chemoproteomic analysis of mitochondrion-related proteins.

The Neuroprotective Effect of Astaxanthin on Pilocarpine-Induced Status Epilepticus in Rats

Cognitive dysfunction is one of the serious complications induced by status epilepticus (SE), which has a significant negative impact on patients’ quality of life. Previous studies demonstrated that the pathophysiological changes after SE such as oxidative stress, inflammatory reaction contribute to neuronal damage. A recent study indicated that preventive astaxanthin (AST) alleviated epilepsy-induced oxidative stress and neuronal apoptosis in the brain. In the present study, rats were treated with vehicle or AST 1 h after SE onset and were injected once every other day for 2 weeks (total of seven times). The results showed that the cognitive function in SE rats was significantly impaired, and AST treatment improved cognitive function in the Morris water maze (MWM). Magnetic resonance imaging (MRI), hematoxylin-eosin (HE) staining and TdT-mediated dUTP Nick-End Labeling (TUNEL) staining showed obvious damage in the hippocampus of SE rats, and AST alleviated the damage. Subsequently, we evaluated the effect of AST on relative pathophysiology to elucidate the possible mechanisms. To evaluate the oxidative stress, the expression of malondialdehyde (MDA) and superoxide dismutase (SOD) in plasma were detected using commercially available kits. NADPH oxidase-4 (Nox-4), p22phox, NF-E2-related factor 2 (Nrf-2), heme oxygenase 1 (Ho-1) and sod1 in the parahippocampal cortex and hippocampus were detected using western blot and real-time polymerase chain reaction (RT-PCR). The levels of MDA in plasma and Nox-4 and p22phox in the brain increased in SE rats, and the levels of SOD in plasma and Nrf-2, Ho-1 and sod1 in the brain decreased. Treatment with AST alleviated these changes. We also detected the levels of inflammatory mediators like cyclooxygenase-2 (cox-2), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and NF-κB phosphorylation p65 (p-p65)/p65 in the brain. The inflammatory reaction was significantly activated in the brain of SE rats, and AST alleviated neuroinflammation. We detected the levels of p-Akt, Akt, B-cell lymphoma-2 (Bcl-2), Bax, cleaved caspase-3, and caspase-3 in the parahippocampal cortex and hippocampus using western blot. The levels of p-Akt/Akt and Bcl-2 decreased in SE rats, Bax and cleaved caspase-3/caspase-3 increased, while AST alleviated these changes. The present study indicated that AST exerted an reobvious neuroprotective effect in pilocarpine-induced SE rats.

Cell senescence, apoptosis and DNA damage cooperate in the remodeling processes accounting for heart morphogenesis

During embryonic development, organ morphogenesis requires major tissue rearrangements that are tightly regulated at the genetic level. A large number of studies performed in recent decades assigned a central role to programmed cell death for such morphogenetic tissue rearrangements that often sculpt the shape of embryonic organs. However, accumulating evidence indicates that far from being the only factor responsible for sculpting organ morphology, programmed cell death is accompanied by other tissue remodeling events that ensure the outcome of morphogenesis. In this regard, cell senescence has been recently associated with morphogenetic degenerative embryonic processes as an early tissue remodeling event in development of the limbs, kidney and inner ear. Here, we have explored cell senescence by monitoring β‐galactosidase activity during embryonic heart development where programmed cell death is believed to exert an important morphogenetic function. We report the occurrence of extensive cell senescence foci during heart morphogenesis. These foci overlap spatially and temporally with the areas of programmed cell death that are associated with remodeling of the outflow tract to build the roots of the great arteries and with the septation of cardiac cavities. qPCR analysis allowed us to identify a gene expression profile characteristic of the so‐called senescence secretory associated phenotype in the remodeling outflow tract of the embryonic heart. In addition, we confirmed local upregulation of numerous tumor suppressor genes including p21, p53, p63, p73 and Btg2. Interestingly, the areas of cell senescence were also accompanied by intense lysosomal activation and non‐apoptotic DNA damage revealed by γH2AX immunolabeling. Considering the importance of sustained DNA damage as a triggering factor for cell senescence and apoptosis, we propose the coordinated contribution of DNA damage, senescence and apoptotic cell death to assure tissue remodeling in the developing vertebrate heart.

Anticancer Cyclometalated Iridium(III) Complexes with Planar Ligands: Mitochondrial DNA Damage and Metabolism Disturbance

Emerging studies have shown that mitochondrial DNA (mtDNA) is a potential target for cancer therapy. Herein, six cyclometalated Ir(III) complexes Ir1-Ir6 containing a series of extended planar diimine ligands have been designed and assessed for their efficacy as anticancer agents. Ir1-Ir6 show much higher cytotoxicity than cisplatin and they can effectively localize to mitochondria. Among them, complexes Ir3 and Ir4 with dipyrido[3,2- a:2',3'- c]phenazine (dppz) ligands can bind to DNA tightly in vitro, intercalate to mtDNA in situ, and induce mtDNA damage. Ir3- and Ir4-impaired mitochondria exhibit decline of mitochondrial membrane potential, disability of adenosine triphosphate generation, disruption of mitochondrial energetic and metabolic status, which subsequently cause protective mitophagy, G₀/G₁ phase cell cycle arrest, and apoptosis. In vivo antitumor evaluations also show that Ir4 can inhibit tumor xenograft growth effectively. Overall, our work proves that targeting the mitochondrial genome may present an effective strategy to develop metal-based anticancer agents to overcome cisplatin resistance.

Mangrove derived Streptomyces sp. MUM265 as a potential source of antioxidant and anticolon-cancer agents

Background

Colon cancer is the third most commonly diagnosed cancer worldwide, with a commensurately high mortality rate. The search for novel antioxidants and specific anticancer agents which may inhibit, delay or reverse the development of colon cancer is thus an area of great interest; Streptomyces bacteria have been demonstrated to be a source of such agents.

Results

The extract from Streptomyces sp. MUM265— a strain which was isolated and identified from Kuala Selangor mangrove forest, Selangor, Malaysia— was analyzed and found to exhibit antioxidant properties as demonstrated via metal-chelating ability as well as superoxide anion, DPPH and ABTS radical scavenging activities. This study also showed that MUM265 extract demonstrated cytotoxicity against colon cancer cells as evidenced by the reduced cell viability of Caco-2 cell line. Treatment with MUM265 extract induced depolarization of mitochondrial membrane potential and accumulation of subG₁ cells in cell cycle analysis, suggesting that MUM265 exerted apoptosis-inducing effects on Caco-2 cells.

Conclusion

These findings indicate that mangrove derived Streptomyces sp. MUM265 represents a valuable bioresource of bioactive compounds for the future development of chemopreventive agents, with particular promise suggested for treatment of colon cancer.

Electronic supplementary material

The online version of this article (10.1186/s12866-019-1409-7) contains supplementary material, which is available to authorized users.

Nanocatalysts-Augmented and Photothermal-Enhanced Tumor-Specific Sequential Nanocatalytic Therapy in Both NIR-I and NIR-II Biowindows

The tumor microenvironment (TME) has been increasingly recognized as a crucial contributor to tumorigenesis. Based on the unique TME for achieving tumor-specific therapy, here a novel concept of photothermal-enhanced sequential nanocatalytic therapy in both NIR-I and NIR-II biowindows is proposed, which innovatively changes the condition of nanocatalytic Fenton reaction for production of highly efficient hydroxyl radicals (•OH) and consequently suppressing the tumor growth. Evidence suggests that glucose plays a vital role in powering cancer progression. Encouraged by the oxidation of glucose to gluconic acid and H₂ O₂ by glucose oxidase (GOD), an Fe₃ O₄ /GOD-functionalized polypyrrole (PPy)-based composite nanocatalyst is constructed to achieve diagnostic imaging-guided, photothermal-enhanced, and TME-specific sequential nanocatalytic tumor therapy. The consumption of intratumoral glucose by GOD leads to the in situ elevation of the H₂ O₂ level, and the integrated Fe₃ O₄ component then catalyzes H₂ O₂ into highly toxic •OH to efficiently induce cancer-cell death. Importantly, the high photothermal-conversion efficiency (66.4% in NIR-II biowindow) of the PPy component elevates the local tumor temperature in both NIR-I and NIR-II biowindows to substaintially accelerate and improve the nanocatalytic disproportionation degree of H₂ O₂ for enhancing the nanocatalytic-therapeutic efficacy, which successfully achieves a remarkable synergistic anticancer outcome with minimal side effects.

Mitochondrial calcium transport and the redox nature of the calcium-induced membrane permeability transition

Mitochondria possess a Ca²⁺ transport system composed of separate Ca²⁺ influx and efflux pathways. Intramitochondrial Ca²⁺ concentrations regulate oxidative phosphorylation, required for cell function and survival, and mitochondrial redox balance, that participates in a myriad of signaling and damaging pathways. The interaction between Ca²⁺ accumulation and redox imbalance regulates opening and closing of a highly regulated inner membrane pore, the membrane permeability transition pore (PTP). In this review, we discuss the regulation of the PTP by mitochondrial oxidants, reactive nitrogen species, and the interactions between these species and other PTP inducers. In addition, we discuss the involvement of mitochondrial redox imbalance and PTP in metabolic conditions such as atherogenesis, diabetes, obesity and in mtDNA stability.

Impact of Maternal Air Pollution Exposure on Children's Lung Health: An Indian Perspective

Air pollution has become an emerging invisible killer in recent years and is a major cause of morbidity and mortality globally. More than 90% of the world’s children breathe toxic air every day. India is among the top ten most highly polluted countries with an average PM₁₀ level of 134 μg/m³ per year. It is reported that 99% of India’s population encounters air pollution levels that exceed the World Health Organization Air Quality Guideline, advising a PM_2.5 permissible level of 10 μg/m³. Maternal exposure to air pollution has serious health outcomes in offspring because it can affect embryonic phases of development during the gestation period. A fetus is more prone to effects from air pollution during embryonic developmental phases due to resulting oxidative stress as antioxidant mechanisms are lacking at that stage. Any injury during this vulnerable period (embryonic phase) will have a long-term impact on offspring health, both early and later in life. Epidemiological studies have revealed that maternal exposure to air pollution increases the risk of development of airway disease in the offspring due to impaired lung development in utero. In this review, we discuss cellular mechanisms involved in maternal exposure to air pollution and how it can impact airway disease development in offspring. A better understanding of these mechanisms in the context of maternal exposure to air pollution can offer a new avenue to prevent the development of airway disease in offspring.

Dynamically Monitoring Cell Viability in a Dual-Color Mode: Construction of an Aggregation/Monomer-Based Probe Capable of Reversible Mitochondria-Nucleus Migration

Mitochondria and nucleus play crucial roles during cell apoptosis process. In this work, a unique fluorescent probe capable of reversible migration between mitochondria and nucleus, as well as detection of cell viability in a dual-color mode is presented. The dual-color probe targets mitochondria in healthy cells, to form aggregates with deep-red emission. It migrates into nucleus and binds to DNA to form monomers with green fluorescence during apoptosis. Interestingly, the migration is reversible dependent on cell viability, which enables the dynamic visualization of apoptosis process. With the probe, mitochondria and nucleus can be visualized in dual colors during apoptosis, and the cell viability could be monitored by the emission color and localization of the probe.

The release of cytochrome c and the regulation of the programmed cell death progress in the endosperm of winter wheat (Triticum aestivum L.) under waterlogging

It has been shown in mammalian systems that the mitochondria can play a key role in the regulation of apoptosis by releasing intermembrane proteins (such as cytochrome c) into the cytosol. Cytochrome c released from the mitochondria to the cytoplasm activates proteolytic enzyme cascades, leading to specific nuclear DNA degradation and cell death. This pathway is considered to be one of the important regulatory mechanisms of apoptosis. Previous studies have shown that endosperm cell development in wheat undergoes specialized programmed cell death (PCD) and that waterlogging stress accelerates the PCD process; however, little is known regarding the associated molecular mechanism. In this study, changes in mitochondrial structure, the release of cytochrome c, and gene expression were studied in the endosperm cells of the wheat (Triticum aestivum L.) cultivar "huamai 8" during PCD under different waterlogging durations. The results showed that waterlogging aggravated the degradation of mitochondrial structure, increased the mitochondrial permeability transition (MPT), and decreased mitochondrial transmembrane potential (ΔΨm), resulting in the advancement of the endosperm PCD process. In situ localization and western blotting of cytochrome c indicated that with the development of the endosperm cell, cytochrome c was gradually released from the mitochondria to the cytoplasm, and waterlogging stress led to an advancement and increase in the release of cytochrome c. In addition, waterlogging stress resulted in the increased expression of the voltage-dependent anion channel (VDAC) and adenine nucleotide translocator (ANT), suggesting that the mitochondrial permeability transition pore (MPTP) may be involved in endosperm PCD under waterlogging stress. The MPTP inhibitor cyclosporine A effectively suppressed cell death and cytochrome c release during wheat endosperm PCD. Our results indicate that the mitochondria play important roles in the PCD of endosperm cells and that the increase in mitochondrial damage and corresponding release of cytochrome c may be one of the major causes of endosperm PCD advancement under waterlogging.

Boron inhibits apoptosis in hyperapoptosis condition: Acts by stabilizing the mitochondrial membrane and inhibiting matrix remodeling

An abnormally high apoptosis has been associated with a number of clinical conditions including embryonal malformations and various pathologies such as neuronal degeneration and diabetes. In this study, boron is reported to inhibit apoptosis in hyperapoptosis conditions as demonstrated in a model of hyperapoptosis. Boron is a metalloid which is present in food in small amounts and is suggested here to inhibit apoptosis by stabilizing the mitochondrial membrane structure, thus preventing matrix remodeling and the release of cytochrome c, an apoptosis-inducer protein from the mitochondrion. The protective effect was assessed by measuring the changes in mitochondrial membrane potential, the levels of cytochrome c and downstream activation of caspase 3, besides phosphatidylserine exposure on the cell surface and DNA damage. The study has implication in clinical conditions characterized by hyperapoptosis as seen in certain embryonal malformations and various pathologies.

Involvement of Mitochondria in Neurodegeneration in Multiple Sclerosis

Functional disruption and neuronal loss followed by progressive dysfunction of the nervous system underlies the pathogenesis of numerous disorders defined as "neurodegenerative diseases". Multiple sclerosis, a chronic inflammatory demyelinating disease of the central nervous system resulting in serious neurological dysfunctions and disability, is one of the most common neurodegenerative diseases. Recent studies suggest that disturbances in mitochondrial functioning are key factors leading to neurodegeneration. In this review, we consider data on mitochondrial dysfunctions in multiple sclerosis, which were obtained both with patients and with animal models. The contemporary data indicate that the axonal degeneration in multiple sclerosis largely results from the activation of Ca2+-dependent proteases and from misbalance of ion homeostasis caused by energy deficiency. The genetic studies analyzing association of mitochondrial DNA polymorphic variants in multiple sclerosis suggest the participation of mitochondrial genome variability in the development of this disease, although questions of the involvement of individual genomic variants are far from being resolved.

Investigation of frequent somatic mutations of MTND5 gene in gastric cancer cell lines and tissues

The present study investigated the single nucleotide variants (SNVs) in mitochondrial DNA (mtDNA) of 13 paired gastric cancer tissue samples and seven gastric cancer cell lines using direct sequencing analysis of the MTND5 region. Results showed that nuclear mitochondrial pseudogenes (NUMTs) and mitochondrial copy number affected the detection of the SNV frequency in gastric cancer tissue and cell line samples using high-throughput sequencing technique. The heteroplasmic point mutation C12474T and G12835A happened in AGS and BGC823 cell lines, respectively. A total of seven SNVs were found in three paired gastric cancer tissue samples, including five heteroplasmic point mutations (A12406G, C12705T, T12882C, G12501A, and A12584G) and two homoplasmic point mutations (G12561A and C13590T). Gastric cancer tissue sample 16 exhibited the highest SNVs frequency with four SNVs (np 12406, np 12705, np 12882, and np 12501), whereas no SNVs or SNPs were detected in the tissue sample 4. SNP 12705 turned out to be an SNV in gastric cancer tissue sample 16. SNV 12338 detected by exome sequencing approach appeared to be an SNP in this study.

Apoptotic Machinery: The Bcl-2 Family Proteins in the Role of Inspectors and Superintendents

Programmed cell death, apoptosis, plays an integral role in a variety of biological events, e.g. morphogenesis, removal of unwanted or harmful cells, tissue homeostasis etc. Members of the Bcl-2 family have been described as the key players in the regulation of the apoptotic process. This family consists of proteins that prevent apoptosis (Bcl-2–like) and two structurally distinct subgroups (Bax-like and BH3–only) that on the contrary promote cell death. Majority of their response is concentrated to the mitochondrial level. In this paper, besides reviewing some new information in this field we focused on how they interact among each other and on the way they sense and influence the death signals from the environment. Here, we compare Bcl-2 family to inspectors and superintendents since they supervise the manufacturing process of cell death and they determine whether the cell will die or it will resist and survive.

Mitochondrial metabolism in pulmonary hypertension: beyond mountains there are mountains

Pulmonary hypertension (PH) is a heterogeneous and fatal disease of the lung vasculature, where metabolic and mitochondrial dysfunction may drive pathogenesis. Similar to the Warburg effect in cancer, a shift from mitochondrial oxidation to glycolysis occurs in diseased pulmonary vessels and the right ventricle. However, appreciation of metabolic events in PH beyond the Warburg effect is only just emerging. This Review discusses molecular, translational, and clinical concepts centered on the mitochondria and highlights promising, controversial, and challenging areas of investigation. If we can move beyond the "mountains" of obstacles in this field and elucidate these fundamental tenets of pulmonary vascular metabolism, such work has the potential to usher in much-needed diagnostic and therapeutic approaches for the mitochondrial and metabolic management of PH.

Single-walled carbon nanohorn aggregates promotes mitochondrial dysfunction-induced apoptosis in hepatoblastoma cells by targeting SIRT3

Single-walled carbon nanohorns (SWNHs) can accumulate in a variety of cell types or tissues and exert biological effects, which have been demonstrated to induce apoptosis in hepatoblastoma cells. However, the role and molecular mechanisms of SWNHs remain unclear. The mitochondrion is an important subcellular structure and may contribute to apoptosis that is induced by SWNHs in hepatoblastoma cells. To address this question, the mitochondrial function of HepG2 or L02 cells that were treated with SWNHs was examined. The results indicated that SWNHs were able to decrease the mitochondrial membrane potential and suppress the activity of the Na⁺/K⁺-ATPase. Secondly, HepG2 cells and L02 cells were treated with SWNHs in vivo and in vitro. The expression of mitochondrial-associated proteins [acyl-CoA synthetase short chain family member 1, Bax, cytochrome C (CYT-C), sodium channel epithelial 1α subunit, sirtuin 3 (SIRT3) and voltage-dependent anion channel 1] was analyzed by western blotting and immunohistochemical staining. The results revealed that SWNH treatment was able to alter the expression of multiple mitochondrial apoptotic pathway-associated proteins in HepG2 cells. SWNH treatment was able upregulate the expression of SIRT3, CYT-C and VDAC1 and downregulate the expression of AceCS2, but it had a more stable effect on SIRT3. However, similar findings were not observed in L02 cells. Therefore, the data from the present study indicated that SWNHs might be used as a safe anticancer agent, where it is able to trigger mitochondrial dysfunction-induced apoptosis by upregulating SIRT3 expression in HepG2 cells.

Oxidative stress and mitochondrial adaptive shift during pituitary tumoral growth

The cellular transformation of normal functional cells to neoplastic ones implies alterations in the cellular metabolism and mitochondrial function in order to provide the bioenergetics and growth requirements for tumour growth progression. Currently, the mitochondrial physiology and dynamic shift during pituitary tumour development are not well understood. Pituitary tumours present endocrine neoplastic benign growth which, in previous reports, we had shown that in addition to increased proliferation, these tumours were also characterized by cellular senescence signs with no indication of apoptosis. Here, we show clear evidence of oxidative stress in pituitary cells, accompanied by bigger and round mitochondria during tumour development, associated with augmented biogenesis and an increased fusion process. An activation of the Nrf2 stress response pathway together with the attenuation of the oxidative damage signs occurring during tumour development were also observed which will probably provide survival advantages to the pituitary cells. These neoplasms also presented a progressive increase in lactate production, suggesting a metabolic shift towards glycolysis metabolism. These findings might imply an oxidative stress state that could impact on the pathogenesis of pituitary tumours. These data may also reflect that pituitary cells can modulate their metabolism to adapt to different energy requirements and signalling events in a pathophysiological situation to obtain protection from damage and enhance their survival chances. Thus, we suggest that mitochondria function, oxidative stress or damage might play a critical role in pituitary tumour progression.

IL-6 knockout mice are protected from cocaine-induced kindling behaviors; possible involvement of JAK2/STAT3 and PACAP signalings

IL-6 has been recognized as an anticonvulsant against certain neuroexcitotoxicities. We aimed to investigate on the interactive role between IL-6 and PACAP in cocaine-induced kindling behaviors. Although we found that cocaine (45 mg/kg, i.p./day x 5) significantly increased IL-6 and TNF-α expression, it resulted in a decrease in IFN-γ expression. We observed that the cocaine-induced increase in IL-6 expression was more pronounced than that in TNF-α expression. Genetic depletion of IL-6 significantly activated cocaine kindling behaviors. This phenomenon was also consistently observed in WT mice that received a neutralizing IL-6 receptor antibody. Cocaine-treated IL-6 knockout mice exhibited significantly decreased PACAP and PACAP receptor (PAC1R) mRNA levels and significantly increased TNF-α gene expression. TNF-α knockout mice were protected from cocaine kindling via an up-regulation of IL-6, phospho-JAK2/STAT3, PACAP, and PAC1R levels, which produced anti-apoptotic effects. Recombinant IL-6 protein (rIL-6, 2 μg, i.v./mouse/day x 5) also up-regulated phospho-JAK2/STAT3, PACAP, and PAC1R mRNA levels, leading to anti-apoptotic effects in IL-6 knockout mice. Consistently, AG490, a JAK2/STAT3 inhibitor, and PACAP 6-38, a PAC1 receptor antagonist, counteracted rIL-6-mediated protection. Combined, our results suggest that IL-6 gene requires up-regulation of phospho-JAK2/STAT3, PACAP, and PAC1R and down-regulation of the TNF-α gene to modulate its anticonvulsive/neuroprotective potential.

Effects of NRF1 on steroidogenesis and apoptosis in goat luteinized granulosa cells

During goat follicular development, abnormal expression of nuclear respiratory factor 1 (NRF1) in granulosa cells may drive follicular atresia with unknown regulatory mechanisms. In this study, we investigated the effects of NRF1 on steroidogenesis and cell apoptosis by overexpressing or silencing it in goat luteinized granulosa cells (LGCs). Results showed that knockdown of NRF1 expression significantly inhibited the expression of STAR and CYP19A1, which are involved in sex steroid hormones synthesis, and led to lower estrogen levels. Knockdown of NRF1 resulted in an increased percentage of apoptosis, probably due to the release of cytochrome c from mitochondria, accompanied by upregulating mRNA and protein levels of apoptosis-related markers BAX, caspase 3 and caspase 9. These data indicate that NRF1 might be related with steroidogenesis and cell apoptosis. Furthermore, NRF1 silence reduced mitochondrial transcription factor A (TFAM) transcription activity, mtDNA copy number and ATP level. Simultaneously, knockdown of NRF1 suppressed the transcription and translation levels of SOD, GPx and CAT, decreased glutathione level and increased 8-OHdG level. However, the overexpression of NRF1 in LGCs or gain of TFAM in NRF1 silenced LGCs increased the expression of genes involved in mitochondrial function and biogenesis, and elevated the antioxidant stress system and steroids synthesis. Taken together, aberrant expression of NRF1 could induce mitochondrial dysfunction and disturb the cellular redox balance, which lead to disturbance of steroid hormone synthesis, and trigger LGC apoptosis through the mitochondria-dependent pathway. These findings will be helpful for understanding the role of NRF1 in goat ovarian follicular development and atresia.

Hinokitiol Inhibits Migration of A549 Lung Cancer Cells via Suppression of MMPs and Induction of Antioxidant Enzymes and Apoptosis

Hinokitiol, a natural monoterpenoid from the heartwood of Calocedrus formosana, has been reported to have anticancer effects against various cancer cell lines. However, the detailed molecular mechanisms and the inhibiting roles of hinokitiol on adenocarcinoma A549 cells remain to be fully elucidated. Thus, the current study was designed to evaluate the effect of hinokitiol on the migration of human lung adenocarcinoma A549 cells in vitro. The data demonstrates that hinokitiol does not effectively inhibit the viability of A549 cells at up to a 10 µM concentration. When treated with non-toxic doses (1–5 µM) of hinokitiol, the cell migration is markedly suppressed at 5 µM. Hinokitiol significantly reduced p53 expression, followed by attenuation of Bax in A549 cells. A dose-dependent inhibition of activated caspase-9 and -3 was observed in the presence of hinokitiol. An observed increase in protein expression of matrix metalloproteinases (MMPs) -2/-9 in A549 cells was significantly inhibited by hinokitiol. Remarkably, when A549 cells were subjected to hinokitiol (1–5 µM), there was an increase in the activities of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) from the reduction in cells. In addition, the incubation of A549 cells with hinokitiol significantly activated the cytochrome c expression, which may be triggered by activation of caspase-9 followed by caspase-3. These observations indicate that hinokitiol inhibited the migration of lung cancer A549 cells through several mechanisms, including the activation of caspases-9 and -3, induction of p53/Bax and antioxidant CAT and SOD, and reduction of MMP-2 and -9 activities. It also induces cytochrome c expression. These findings demonstrate a new therapeutic potential for hinokitiol in lung cancer chemoprevention.

Novel host restriction factors implicated in HIV-1 replication

Human immunodeficiency virus-1 (HIV-1) is known to interact with multiple host cellular proteins during its replication in the target cell. While many of these host cellular proteins facilitate viral replication, a number of them are reported to inhibit HIV-1 replication at various stages of its life cycle. These host cellular proteins, which are known as restriction factors, constitute an integral part of the host's first line of defence against the viral pathogen. Since the discovery of apolipoprotein B mRNA-editing enzyme 3G (APOBEC3G) as an HIV-1 restriction factor, several human proteins have been identified that exhibit anti-HIV-1 restriction. While each restriction factor employs a distinct mechanism of inhibition, the HIV-1 virus has equally evolved complex counter strategies to neutralize their inhibitory effect. APOBEC3G, tetherin, sterile alpha motif and histidine-aspartate domain 1 (SAMHD1), and trim-5α are some of the best known HIV-1 restriction factors that have been studied in great detail. Recently, six novel restriction factors were discovered that exhibit significant antiviral activity: endoplasmic reticulum α1,2-mannosidase I (ERManI), translocator protein (TSPO), guanylate-binding protein 5 (GBP5), serine incorporator (SERINC3/5) and zinc-finger antiviral protein (ZAP). The focus of this review is to discuss the antiviral mechanism of action of these six restriction factors and provide insights into the probable counter-evasion strategies employed by the HIV-1 virus. The recent discovery of new restriction factors substantiates the complex host-pathogen interactions occurring during HIV-1 pathogenesis and makes it imperative that further investigations are conducted to elucidate the molecular basis of HIV-1 replication.

Effects of d-galactose-induced ageing on the heart and its potential interventions

Ageing is a strong independent risk factor for disability, morbidity and mortality. Post-mitotic cells including those in the heart are a particular risk to age-related deterioration. As the occurrence of heart disease is increasing rapidly with an ageing population, knowledge regarding the mechanisms of age-related cardiac susceptibility and possible therapeutic interventions needs to be acquired to prevent advancing levels of heart disease. To understand more about the ageing heart, numerous aged animal models are being used to explore the underlying mechanisms. Due to time-consuming for investigations involving naturally aged animals, mimetic ageing models are being utilized to assess the related effects of ageing on disease occurrence. d-galactose is one of the substances used to instigate ageing in various models, and techniques involving this have been widely used since 1991. However, the mechanism through which d-galactose induces ageing in the heart remains unclear. The aim of this review was to comprehensively summarize the current findings from in vitro and in vivo studies on the effects of d-galactose-induced ageing on the heart, and possible therapeutic interventions against ageing heart models. From this review, we hope to provide invaluable information for future studies and based on the findings from experiments involving animals, we can inform possible therapeutic strategies for the prevention of age-related heart diseases in clinical settings.

Protonation state of glutamate 73 regulates the formation of a specific dimeric association of mVDAC1

The voltage-dependent anion channel (VDAC) is the most abundant protein in the outer mitochondrial membrane and constitutes the primary pathway for the exchange of ions and metabolites between the cytosol and the mitochondria. There is accumulating evidence supporting VDAC's role in mitochondrial metabolic regulation and apoptosis, where VDAC oligomerization has been implicated with these processes. Herein, we report a specific pH-dependent dimerization of murine VDAC1 (mVDAC1) identified by double electron-electron resonance and native mass spectrometry. Intermolecular distances on four singly spin-labeled mVDAC1 mutants were used to generate a model of the low-pH dimer, establishing the presence of residue E73 at the interface. This dimer arrangement is different from any oligomeric state previously described, and it forms as a steep function of pH with an apparent pK_a of 7.4. Moreover, the monomer-dimer equilibrium affinity constant was determined using native MS, revealing a nearly eightfold enhancement in dimerization affinity at low pH. Mutation of E73 to either alanine or glutamine severely reduces oligomerization, demonstrating the role of protonated E73 in enhancing dimer formation. Based on these results, and the known importance of E73 in VDAC physiology, VDAC dimerization likely plays a significant role in mitochondrial metabolic regulation and apoptosis in response to cytosolic acidification during cellular stress.

Ant1 mutant mice bridge the mitochondrial and serotonergic dysfunctions in bipolar disorder

Although mitochondrial and serotonergic dysfunctions have been implicated in the etiology of bipolar disorder (BD), the relationship between these unrelated pathways has not been elucidated. A family of BD and chronic progressive external ophthalmoplegia (CPEO) caused by a mutation of the mitochondrial adenine nucleotide translocator 1 (ANT1, SLC25A4) implicated that ANT1 mutations confer a risk of BD. Here, we sequenced ANT1 in 324 probands of NIMH bipolar disorder pedigrees and identified two BD patients carrying heterozygous loss-of-function mutations. Behavioral analysis of brain specific Ant1 heterozygous conditional knockout (cKO) mice using lntelliCage showed a selective diminution in delay discounting. Delay discounting is the choice of smaller but immediate reward than larger but delayed reward and an index of impulsivity. Diminution of delay discounting suggests an increase in serotonergic activity. This finding was replicated by a 5-choice serial reaction time test. An anatomical screen showed accumulation of COX (cytochrome c oxidase) negative cells in dorsal raphe. Dorsal raphe neurons in the heterozygous cKO showed hyperexcitability, along with enhanced serotonin turnover in the nucleus accumbens and upregulation of Maob in dorsal raphe. These findings altogether suggest that mitochondrial dysfunction as the genetic risk of BD may cause vulnerability to BD by altering serotonergic neurotransmission.

Proteomic investigation of effects of hydroxysafflor yellow A in oxidized low-density lipoprotein-induced endothelial injury

Oxidized low-density lipoprotein (ox-LDL)-induced vascular endothelial damage is a key event in early atherosclerosis. Safflower has been used to treat atherosclerotic heart disease in China for many years, but its molecular basis remains unclear. Hydroxysafflor yellow A (HSYA) is the main active ingredient of aqueous safflower extract. We identified the proteins involved in HSYA activity against ox-LDL-induced endothelial injury using isobaric tags for relative and absolute quantification-coupled two-dimensional liquid chromatography–tandem mass spectrometry. HSYA (1, 5, or 25 μM) alleviated ox-LDL-induced endothelial damage in a dose-dependent manner. We quantitated approximately 2700 protein species, of which 77 were differentially expressed following HSYA treatment. Most protein changes were related to structural molecules, metabolic enzymes, and proteins involved in signal transduction. Several differentially expressed proteins were further validated by western blot analysis. We also analysed the role of the mitochondrial membranous voltage-dependent anion-selective channel protein 2 (VDAC2) in HSYA treatment using small interfering RNA. VDAC2 functioned as a downstream anti-apoptosis effector during HSYA treatment of ox-LDL-induced endothelial impairment. These results further our understanding of the mechanisms responsible for the effects of HSYA.

Toxicity and structure-activity relationship (SAR) of α,β-dehydroamino acids against human cancer cell lines

A library of N-protected dehydroamino acids, namely dehydroalanine, dehydroaminobutyric acid and dehydrophenylalanine derivatives, was screened in three human cancer cell lines [(lung (A549), gastric (AGS) and neuroblastoma (SH-SY5Y)] in order to characterize their toxicological profile and identify new molecules with potential anticancer activity. Results showed N-protected dehydrophenylalanine and dehydroaminobutyric acid derivatives have no or low toxicity for all tested cell lines. The N-protected dehydroalanines exhibit significant toxic effects and the AGS and SH-SY5Y cells were significantly more vulnerable than A549 cells. Four α,β-dehydroalanine derivatives, with IC₅₀<62.5μM, were selected to investigate the pathways by which these compounds promote cell death. All compounds, at their IC₅₀ concentrations, were able to induce apoptosis in both AGS and SH-SY5Y cell lines. In both cell lines, loss of mitochondrial membrane potential (ΔΨm) was found and caspase activity was increased, namely endoplasmic reticulum-resident caspase-4 in AGS cells and caspase-3/7 in SH-SY5Y cells. When evaluated in a non-cancer cell line, the molecules displayed no to low toxicity, thus suggesting some degree of selectivity for cancer cells. The results indicate that α,β-dehydroalanine derivatives can be considered a future resource of compounds able to work as anticancer drugs.