New role of the BCL2 family of proteins in the regulation of mitochondrial dynamics

Fusion-fission-mitophagy cycling and metabolic reprogramming coordinate nerve growth factor (NGF)-dependent neuronal differentiation

Neuronal differentiation is regulated by nerve growth factor (NGF) and other neurotrophins. We explored the impact of NGF on mitochondrial dynamics and metabolism through time-lapse imaging, metabolomics profiling, and computer modeling studies. We show that NGF may direct differentiation by stimulating fission, thereby causing selective mitochondrial network fragmentation and mitophagy, ultimately leading to increased mitochondrial quality and respiration. Then, we reconstructed the dynamic fusion-fission-mitophagy cycling of mitochondria in a computer model, integrating these processes into a single network mechanism. Both the computational model and the simulations are able to reproduce the proposed mechanism in terms of mitochondrial dynamics, levels of reactive oxygen species (ROS), mitophagy, and mitochondrial quality, thus providing a computational tool for the interpretation of the experimental data and for future studies aiming to detail further the action of NGF on mitochondrial processes. We also show that changes in these mitochondrial processes are intertwined with a metabolic function of NGF in differentiation: NGF directs a profound metabolic rearrangement involving glycolysis, TCA cycle, and the pentose phosphate pathway, altering the redox balance. This metabolic rewiring may ensure: (a) supply of both energy and building blocks for the anabolic processes needed for morphological reorganization, as well as (b) redox homeostasis.

Nuclear factor-Y mediates pancreatic β-cell compensation by repressing reactive oxygen species-induced apoptosis under metabolic stress

BACKGROUND

Pancreatic β-cells elevate insulin production and secretion through a compensatory mechanism to override insulin resistance under metabolic stress conditions. Deficits in β-cell compensatory capacity result in hyperglycemia and type 2 diabetes (T2D). However, the mechanism in the regulation of β-cell compensative capacity remains elusive. Nuclear factor-Y (NF-Y) is critical for pancreatic islets' homeostasis under physiological conditions, but its role in β-cell compensatory response to insulin resistance in obesity is unclear.

METHODS

In this study, using obese ( ob/ob ) mice with an absence of NF-Y subunit A (NF-YA) in β-cells ( ob , Nf-ya βKO) as well as rat insulinoma cell line (INS1)-based models, we determined whether NF-Y-mediated apoptosis makes an essential contribution to β-cell compensation upon metabolic stress.

RESULTS

Obese animals had markedly augmented NF-Y expression in pancreatic islets. Deletion of β-cell Nf-ya in obese mice worsened glucose intolerance and resulted in β-cell dysfunction, which was attributable to augmented β-cell apoptosis and reactive oxygen species (ROS). Furthermore, primary pancreatic islets from Nf-ya βKO mice were sensitive to palmitate-induced β-cell apoptosis due to mitochondrial impairment and the attenuated antioxidant response, which resulted in the aggravation of phosphorylated c-Jun N-terminal kinase (JNK) and cleaved caspase-3. These detrimental effects were completely relieved by ROS scavenger. Ultimately, forced overexpression of NF-Y in INS1 β-cell line could rescue palmitate-induced β-cell apoptosis, dysfunction, and mitochondrial impairment.

CONCLUSION

Pancreatic NF-Y might be an essential regulator of β-cell compensation under metabolic stress.

The biological function of the long non-coding RNA endogenous born avirus-like nucleoprotein in lung adenocarcinoma is mediated through the microRNA-655-3p/B-cell lymphoma-2 axis

Lung adenocarcinoma (LUAD) is a subtype of lung cancer, and therapy remains a great challenge. A growing body of evidence shows that long-chain non-coding RNAs (lncRNAs) play an important role in the occurrence and development of LUAD. This study investigated the roles and mechanisms of action of EBLN3P in LUAD. The bioinformatics software starBase and TargetScan were used to predict the binding sites of the lncRNA endogenous born avirus-like nucleoprotein (EBLN3P) and microRNA (miR)-655-3p in LUAD. The regulatory role of EBLN3P and miR-655-3p in cell proliferation was verified through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT) assay. The binding sites between EBLN3P, miR-655-3p, and B-cell lymphoma-2 (Bcl-2) were assessed using dual-luciferase reporter assay, western blotting, and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Flow cytometry (FCM) was performed to analyze the apoptotic rates of A549 cells after transfection. The results revealed that EBLN3P was upregulated, whereas miR-655-3p was downregulated in LUAD cell lines (A549 and NCI-H23). Bioinformatics analysis and dual-luciferase reporter assays indicated that EBLN3P interacted with miR-655-3p. Knockdown of EBLN3P notably inhibited the bioactivity and induced apoptosis in A549 cells by upregulating miR-655-3p. Mechanistically, miR-655-3p inhibits cell viability and induces apoptosis by inhibiting Bcl-2 expression. The high expression of Bcl-2 reversed the impact of miR-655-3p on the inhibition of cell bioactivity and induction of apoptosis in A549 cells. In conclusion, this study demonstrated that EBLN3P silencing inhibits bioactivity and induces apoptosis via the miR-655-3p/Bcl-2 axis, providing a potential therapeutic target for lung adenocarcinoma.

Xyloketal B: A marine compound with medicinal potential

In recent decades, technological advantages have allowed scientists to isolate medicinal compounds from marine organisms that exhibit unique structure and bioactivity. The mangrove fungus Xylaria sp. from the South China Sea is rich in metabolites and produces a potent therapeutic compound, xyloketal B. Since its isolation in 2001, xyloketal B has been extensively studied in a wide variety of cell types and in vitro and in vivo disease models. Xyloketal B and its derivatives exhibit cytoprotective effects in cardiovascular and neurodegenerative diseases by reducing oxidative stress, regulating the apoptosis pathway, maintaining ionic balance, mitigating inflammatory responses, and preventing protein aggregation. Xyloketal B has also shown to alleviate lipid accumulation in a non-alcoholic fatty liver disease model. Moreover, xyloketal B treatment induces glioblastoma cell death. This review summarizes our current understanding of xyloketal B in various disease models.

BCL(X)L and BCL2 increase the metabolic fitness of breast cancer cells: a single-cell imaging study

The BCL2 family of proteins regulate apoptosis by controlling mitochondrial outer membrane permeability. However, the effects on mitochondrial structure and bioenergetics have also been reported. Here we comprehensively characterized the effects of BCL2 and BCL(X)L on cellular energetics in MCF7 breast cancer cells using time-lapse confocal single-cell imaging and mitochondrial and cytosolic FRET reporters. We found that BCL2 and BCL(X)L increase the metabolic robustness of MCF7 cells, and that this was associated with increased mitochondrial NAD(P)H and ATP levels. Experiments with the F₁F₀ synthase inhibitor oligomycin demonstrated that BCL2 and in particular BCL(X)L, while not affecting ATP synthase activity, more efficiently coupled the mitochondrial proton motive force with ATP production. This metabolic advantage was associated with an increased resistance to nutrient deprivation and enhanced clonogenic survival in response to metabolic stress, in the absence of profound effects on cell death. Our data suggest that a primary function of BCL(X)L and BCL2 overexpression in tumor cells is to increase their resistance to metabolic stress in the tumor microenvironment, independent of cell death signaling.

Exogenous Alpha-Synuclein Evoked Parkin Downregulation Promotes Mitochondrial Dysfunction in Neuronal Cells. Implications for Parkinson's Disease Pathology

Aberrant secretion and accumulation of α-synuclein (α-Syn) as well as the loss of parkin function are associated with the pathogenesis of Parkinson's disease (PD). Our previous study suggested a functional interaction between those two proteins, showing that the extracellular α-Syn evoked post-translational modifications of parkin, leading to its autoubiquitination and degradation. While parkin plays an important role in mitochondrial biogenesis and turnover, including mitochondrial fission/fusion as well as mitophagy, the involvement of parkin deregulation in α-Syn-induced mitochondrial damage is largely unknown. In the present study, we demonstrated that treatment with exogenous α-Syn triggers mitochondrial dysfunction, reflected by the depolarization of the mitochondrial membrane, elevated synthesis of the mitochondrial superoxide anion, and a decrease in cellular ATP level. At the same time, we observed a protective effect of parkin overexpression on α-Syn-induced mitochondrial dysfunction. α-Syn-dependent disturbances of mitophagy were also shown to be directly related to reduced parkin levels in mitochondria and decreased ubiquitination of mitochondrial proteins. Also, α-Syn impaired mitochondrial biosynthesis due to the parkin-dependent reduction of PGC-1α protein levels. Finally, loss of parkin function as a result of α-Syn treatment induced an overall breakdown of mitochondrial homeostasis that led to the accumulation of abnormal mitochondria. These findings may thus provide the first compelling evidence for the direct association of α-Syn-mediated parkin depletion to impaired mitochondrial function in PD. We suggest that improvement of parkin function may serve as a novel therapeutic strategy to prevent mitochondrial impairment and neurodegeneration in PD (thereby slowing the progression of the disease).

The function of apolipoproteins L (APOLs): relevance for kidney disease, neurotransmission disorders, cancer and viral infection

The discovery that apolipoprotein L1 (APOL1) is the trypanolytic factor of human serum raised interest about the function of APOLs, especially following the unexpected finding that in addition to their protective action against sleeping sickness, APOL1 C-terminal variants also cause kidney disease. Based on the analysis of the structure and trypanolytic activity of APOL1, it was proposed that APOLs could function as ion channels of intracellular membranes and be involved in mechanisms triggering programmed cell death. In this review, the recent finding that APOL1 and APOL3 inversely control the synthesis of phosphatidylinositol-4-phosphate (PI(4)P) by the Golgi PI(4)-kinase IIIB (PI4KB) is commented. APOL3 promotes Ca2+ -dependent activation of PI4KB, but due to their increased interaction with APOL3, APOL1 C-terminal variants can inactivate APOL3, leading to reduction of Golgi PI(4)P synthesis. The impact of APOLs on several pathological processes that depend on Golgi PI(4)P levels is discussed. I propose that through their effect on PI4KB activity, APOLs control not only actomyosin activities related to vesicular trafficking, but also the generation and elongation of autophagosomes induced by inflammation.

Bax and Bak jointly control survival and dampen the early unfolded protein response in pancreatic β-cells under glucolipotoxic stress

ER stress and apoptosis contribute to the loss of pancreatic β-cells under pro-diabetic conditions of glucolipotoxicity. Although activation of canonical intrinsic apoptosis is known to require pro-apoptotic Bcl-2 family proteins Bax and Bak, their individual and combined involvement in glucolipotoxic β-cell death are not known. It has also remained an open question if Bax and Bak in β-cells have non-apoptotic roles in mitochondrial function and ER stress signaling, as suggested in other cell types. Using mice with individual or combined β-cell deletion of Bax and Bak, we demonstrated that glucolipotoxic β-cell death in vitro occurs by both non-apoptotic and apoptotic mechanisms, and the apoptosis could be triggered by either Bax or Bak alone. In contrast, they had non-redundant roles in mediating staurosporine-induced apoptosis. We further established that Bax and Bak do not affect normal glucose-stimulated β-cell Ca²⁺ responses, insulin secretion, or in vivo glucose tolerance. Finally, our experiments revealed that combined deletion of Bax and Bak amplified the unfolded protein response in islets during the early stages of chemical- or glucolipotoxicity-induced ER stress. These findings shed new light on roles of the core apoptosis machinery in β-cell survival and stress signals of importance for the pathobiology of diabetes.

Mitophagy, Mitochondrial Homeostasis, and Cell Fate

Mitochondria are highly plastic and dynamic organelles that have graded responses to the changing cellular, environmental, and developmental cues. Mitochondria undergo constant mitochondrial fission and fusion, mitochondrial biogenesis, and mitophagy, which coordinately control mitochondrial morphology, quantity, quality, turnover, and inheritance. Mitophagy is a cellular process that selectively removes the aged and damaged mitochondria via the specific sequestration and engulfment of mitochondria for subsequent lysosomal degradation. It plays a pivotal role in reinstating cellular homeostasis in normal physiology and conditions of stress. Damaged mitochondria may either instigate innate immunity through the overproduction of ROS or the release of mtDNA, or trigger cell death through the release of cytochrome c and other apoptogenic factors when mitochondria damage is beyond repair. Distinct molecular machineries and signaling pathways are found to regulate these mitochondrial dynamics and behaviors. It is less clear how mitochondrial behaviors are coordinated at molecular levels. BCL2 family proteins interact within family members to regulate mitochondrial outer membrane permeabilization and apoptosis. They were also described as global regulators of mitochondrial homeostasis and mitochondrial fate through their interaction with distinct partners including Drp1, mitofusins, PGAM5, and even LC3 that involved mitochondrial dynamics and behaviors. In this review, we summarize recent findings on molecular pathways governing mitophagy and its coordination with other mitochondrial behaviors, which together determine cellular fate.

Novel Insights into the Roles of Bcl-2 Homolog Nr-13 (vNr-13) Encoded by Herpesvirus of Turkeys in the Virus Replication Cycle, Mitochondrial Networks, and Apoptosis Inhibition

The Bcl-2 (B cell lymphoma 2)-related protein Nr-13 plays a major role in the regulation of cell death in developing avian B cells. With over 65% sequence similarity to the chicken Nr-13, herpesvirus of turkeys (HVT) vNr-13, encoded by the HVT079 and HVT096 genes, is the first known alphaherpesvirus-encoded Bcl-2 homolog. HVT-infected cells were reported to be relatively more resistant to serum starvation, suggested that vNr-13 could be involved in protecting the cells. Here, we describe CRISPR/Cas9-based editing of exon 1 of the HVT079 and HVT096 genes from the HVT genome to generate the mutant HVT-ΔvNr-13 to gain insights into its functional roles. Overall, wild-type HVT and HVT-ΔvNr-13 showed similar growth kinetics; however, at early time points, HVT-ΔvNr-13 showed 1.3- to 1.7-fold-lower growth of cell-associated virus and 3- to 6.2-fold-lower growth of cell-free virus. In transfected cells, HVT vNr-13 showed a mainly diffuse cytoplasmic distribution with faint nuclear staining. Further, vNr-13 localized to the mitochondria and endoplasmic reticulum (ER) and disrupted mitochondrial network morphology in the transfected cells. In the wild-type HVT-infected cells, vNr-13 expression appeared to be directly involved in the disruption of the mitochondrial network, as the mitochondrial network morphology was substantially restored in the HVT-ΔvNr-13-infected cells. IncuCyte S3 real-time apoptosis monitoring demonstrated that vNr-13 is unequivocally involved in the apoptosis inhibition, and it is associated with an increase of PFU, especially under serum-free conditions in the later stages of the viral replication cycle. Furthermore, HVT blocks apoptosis in infected cells but activates apoptosis in noninfected bystander cells.IMPORTANCE B cell lymphoma 2 (Bcl-2) family proteins play important roles in regulating apoptosis during homeostasis, tissue development, and infectious diseases. Several viruses encode homologs of cellular Bcl-2-proteins (vBcl-2) to inhibit apoptosis, which enable them to replicate and persist in the infected cells and to evade/modulate the immune response of the host. Herpesvirus of turkeys (HVT) is a nonpathogenic alphaherpesvirus of turkeys and chickens that is widely used as a live vaccine against Marek's disease and as recombinant vaccine viral vectors for protecting against multiple avian diseases. Identical copies of the HVT genes HVT079 and HVT096 encode the Bcl-2 homolog vNr-13. While previous studies have identified the potential ability of vNr-13 in inhibiting apoptosis induced by serum deprivation, there have been no detailed investigations on the functions of vNr-13. Using CRISPR/Cas9-based ablation of the vNr-13 gene, we demonstrated the roles of HVT vNr-13 in early stages of the viral replication cycle, mitochondrial morphology disruption, and apoptosis inhibition in later stages of viral replication.

Neurotoxicity and apoptosis induced by pyrroloquinoline quinone and its ester derivative on primary cortical neurons

Pyrroloquinoline quinone (PQQ) and its esterified derivative, PQQ ester (PQQE), have potential to treat or diagnose neurological and psychological disorders. However, their neurotoxicity remains unclear. To provide reference data for the brain targeting drug delivery techniques, the cytotoxic effects of PQQ and PQQE were examined in primary mouse cortical neurons. The results indicated that both PQQ and PQQE decreased neuron viability, reduced intracellular ATP level and disrupted the mitochondrial membrane potential in a concentration- and time-dependent manner, while PQQ was less potent than PQQE. PQQ and PQQE induced apoptosis involving increase of Bax, decrease of Bcl-2, release of mitochondrial cytochrome C into the cytosol, activation of caspase-3 and cleavage of PARP. A single mouse intracephalic injection of PQQ or PQQE showed similar results. Based on these findings, high-concentration PQQ or PQQE treatment could induce a wide range of neurotoxicity and apoptosis. The lowest observed adverse effect levels (LOAELs) of PQQ and PQQE were 10 μM and 2 μM respectively and the no observed adverse effect levels (NOAELs) were 5 μM and 1 μM respectively in mice cortical neurons.

The mitomiR/Bcl-2 axis affects mitochondrial function and autophagic vacuole formation in senescent endothelial cells

During senescence, cells undergo distinctive biochemical and morphological changes and become dysfunctional. MiRNAs are involved in the senescence process and specific miRNAs can localize to mitochondria (mitomiRs). We hypothesized that part of the typical alterations of senescence may depends on mitomiRs deregulation. Therefore, we thoroughly explored the phenotype of human endothelial cells undergoing replicative senescence (sHUVECs) and observed elongated/branched mitochondria, accumulation of autophagic vacuoles (AVs), increased ROS and IL-1β production and reduced expression of Bcl-2 compared to younger cells (yHUVECs). Despite these pro-apoptotic features, sHUVECs are more resistant to serum deprivation, conceivably due to development of pro-survival strategies such as upregulation of Bcl-xL and Survivin. We demonstrate that mitomiR-181a, -34a, and -146a, are overexpressed and localize to mitochondria in sHUVECs compared with yHUVECs and that they: i) down-regulate Bcl-2, ii) induce permeability transition pore opening and activation of caspase-1 and 3, iii) affect sensitivity to apoptosis and iv) promote the conversion of LC3-I to LC3-II. Overall, we document for the first time that some mitomiRs can act as mediators of the multiple but functionally linked biochemical and morphological changes that characterize aging cells and that they can promote different cellular outcomes according to the senescence status of the cell.

A novel thiosemicarbazone as a promising effective and selective compound for acute leukemia

Acute leukemias are a heterogeneous group of aggressive malignant neoplasms associated with severe morbidities due to the nonselectivity of current chemotherapeutic drugs to nonmalignant cells. The investigation of novel natural and synthetic structures that might be used for the development of new drugs with greater efficiency and selectivity to leukemic cells is mandatory. In this context, thiosemicarbazones have been well described in the literature by their several biological properties and their reaction is known as versatile, low-cost, and highly chemoselective. With this perspective, this study aimed to investigate the cytotoxic effect and the main death mechanisms of a novel thiosemicarbazone (LAP17) on acute leukemia cell lines K562 and Jurkat. The results show that the strong cytotoxic effect of LAP17 to leukemic cells is due to apoptosis induction, which resulted in caspase-3 activation and DNA fragmentation. Intrinsic apoptosis seems to be related to the inversion of Bax/Bcl-2 expression, ΔΨm loss, and AIF release, whereas extrinsic apoptosis was initiated by FasR. Gene-expression profiling of HL-60 cells treated with LAP17 by the microarray technique revealed a significant enrichment of gene sets related to cell cycle arrest at G2/M. Accordingly, K562 and Jurkat cells treated with LAP17 revealed a clear arrest at G2/M phase. Taking into consideration that LAP17 was not cytotoxic to nonhematological cells (peripheral blood mononuclear cell and erythrocytes), these results suggest that LAP17 is a promising new compound that might be used as a prototype for the development of new antileukemic agents.

The pro-survival function of DLEC1 and its protection of cancer cells against 5-FU-induced apoptosis through up-regulation of BCL-XL

The tumor suppressor DLEC1 has been shown to promote cell proliferation when AP-2α2 is down-regulated in HCT116 stable clones, suggesting its pro-survival nature. However, the pro-survival function of DLEC1 has not been confirmed in other cells and its underlying mechanisms remain elusive. Therefore, we knocked down DLEC1 in a panel of cell lines and found that DLEC1 depletion caused various extents of cell death through intrinsic pathway. DLEC1 overexpression promoted cell survival and reduced cell death in cancer cells after 5-FU treatment, while DLEC1 down-regulation sensitized cancer cells to 5-FU. Further studies demonstrated that DLEC1 attenuated the increase in cleaved PARP, caspase-3 and caspase-7, the activity of caspase-9 and the diffusion of cytosolic cytochrome c from mitochondria. Our data also showed that BCL-XL was up-regulated by DLEC1 in stable clones after 5-FU treatment. Altogether, these results indicated that DLEC1 protects cells against cell death induced by 5-FU through the attenuation of active proteins in caspase cascade and the up-regulation of BCL-XL. Therefore, DLEC1 can be a pro-survival protein under certain circumstances and a potential therapeutic target for increasing sensitivity of cancer cells to 5-FU.

Marine Compound Xyloketal B as a Potential Drug Development Target for Neuroprotection

Xyloketal B is a natural compound isolated from the mangrove fungus, Xylaria sp. in the South China Sea. In the past decade, studies have shown that xyloketal B exhibits anti-oxidative, anti-inflammatory, and anti-apoptotic abilities and may serve as a treatment for ischemic stroke. Xyloketal B has been shown to interact with both neurons and residential microglial cells and regulate a number of proteins involved in the apoptotic events during ischemia. Such mechanisms include inhibition of specific NADPH oxidase subunits, upregulation of HO-1, increase of Bcl-1/Bax ratio, and downregulation of TLR4 receptor. Both in vitro and in vivo stroke models have validated its potential in preventing ischemia-induced neuronal cell death. This review summarizes our current understanding of the effects of xyloketal B in ischemic conditions. As stroke ranks second in the causes of mortality worldwide and still lacks effective treatment, it is necessary to seek novel therapeutic options. Understanding the role of xyloketal B in ischemic stroke could reveal a new aspect of stroke treatment.

Cross Talk Between Cellular Redox State and the Antiapoptotic Protein Bcl-2

SIGNIFICANCE

B cell lymphoma-2 (Bcl-2) was discovered over three decades ago and is the prototype antiapoptotic member of the Bcl-2 family that comprises proteins with contrasting effects on cell fate. First identified as a consequence of chromosomal translocation (t 14:18) in human lymphoma, subsequent studies have revealed mutations and/or gene copy number alterations as well as post-translational modifications of Bcl-2 in a variety of human cancers. The canonical function of Bcl-2 is linked to its ability to inhibit mitochondrial membrane permeabilization, thereby regulating apoptosome assembly and activation by blocking the cytosolic translocation of death amplification factors. Of note, the identification of specific domains within the Bcl-2 family of proteins (Bcl-2 homology domains; BH domains) has not only provided a mechanistic insight into the various interactions between the member proteins but has also been the impetus behind the design and development of small molecule inhibitors and BH3 mimetics for clinical use. Recent Advances: Aside from its role in maintaining mitochondrial integrity, recent evidence provides testimony to a novel facet in the biology of Bcl-2 that involves an intricate cross talk with cellular redox state. Bcl-2 overexpression modulates mitochondrial redox metabolism to create a "pro-oxidant" milieu, conducive for cell survival. However, under states of oxidative stress, overexpression of Bcl-2 functions as a redox sink to prevent excessive buildup of reactive oxygen species, thereby inhibiting execution signals. Emerging evidence indicates various redox-dependent transcriptional changes and post-translational modifications with different functional outcomes.

CRITICAL ISSUES

Understanding the complex interplay between Bcl-2 and the cellular redox milieu from the standpoint of cell fate signaling remains vital for a better understanding of pathological states associated with altered redox metabolism and/or aberrant Bcl-2 expression.

FUTURE DIRECTIONS

Based on its canonical functions, Bcl-2 has emerged as a potential druggable target. Small molecule inhibitors of Bcl-2 and/or other family members with similar function, as well as BH3 mimetics, are showing promise in the clinic. The emerging evidence for the noncanonical activity linked to cellular redox metabolism provides a novel avenue for the design and development of diagnostic and therapeutic strategies against cancers refractory to conventional chemotherapy by the overexpression of this prosurvival protein.

Antitubulin sulfonamides: The successful combination of an established drug class and a multifaceted target

Tubulin, the microtubules and their dynamic behavior are amongst the most successful antitumor, antifungal, antiparasitic, and herbicidal drug targets. Sulfonamides are exemplary drugs with applications in the clinic, in veterinary and in the agrochemical industry. This review summarizes the actual state and recent progress of both fields looking from the double point of view of the target and its drugs, with special focus onto the structural aspects. The article starts with a brief description of tubulin structure and its dynamic assembly and disassembly into microtubules and other polymers. Posttranslational modifications and the many cellular means of regulating and modulating tubulin's biology are briefly presented in the tubulin code. Next, the structurally characterized drug binding sites, their occupying drugs and the effects they induce are described, emphasizing on the structural requirements for high potency, selectivity, and low toxicity. The second part starts with a summary of the favorable and highly tunable combination of physical-chemical and biological properties that render sulfonamides a prototypical example of privileged scaffolds with representatives in many therapeutic areas. A complete description of tubulin-binding sulfonamides is provided, covering the different species and drug sites. Some of the antimitotic sulfonamides have met with very successful applications and others less so, thus illustrating the advances, limitations, and future perspectives of the field. All of them combine in a mechanism of action and a clinical outcome that conform efficient drugs.

BCL2 and miR-181a transcriptional alterations in umbilical-cord blood cells can be putative biomarkers for obesity

Several findings suggest that in utero stressor stimuli can alter fetal development by promoting transcriptional changes, and predisposing the neonate to diseases later in life. This study aimed to investigate whether a hyperglycemic environment in pregnant women with gestational diabetes mellitus (GDM) is able to cause fetal genetic alterations and predispose neonates to obesity. Transcriptional alteration of SIRT1, TP53 and BCL2 genes, miR-181a (a SIRT1 or BCL2 regulator) and telomere length were evaluated in placental and umbilical-cord blood cells. Healthy (HP; n = 20) and GDM (n = 20) pregnant women and their respective neonates were included in the study. Additionally, obese (n = 20) and eutrophic (n = 20) adults also participated as reference populations. Gene expression data showed down-regulation of BCL2 in umbilical-cord and peripheral blood cells from GDM neonates and obese adults, respectively. The miR-181a was down-regulated only in umbilical-cord blood cells of GDM neonates. Telomere length presented no significant difference. In conclusion, our study demonstrated that the GDM hyperglycemic intrauterine environment promotes transcriptional alterations in BCL2 and miR-181a in neonate umbilical-cord blood cells. Furthermore, both GDM neonates and obese subjects share the same transcriptional alteration in BCL2. Considering the relationship between obesity development and the functions regulated by these two genes, BCL2 and miR-181a could be adopted as potential biomarkers for childhood obesity. However, further study designs are recommended to confirm this hypothesis.

Autophagy activation is required for influenza A virus-induced apoptosis and replication

Autophagy and apoptosis are two major interconnected host cell responses to viral infection, including influenza A virus (IAV). Thus, delineating these events could facilitate the development of better treatment options and provide an effective anti-viral strategy for controlling IAV infection. We used A549 cells and mouse embryonic fibroblasts (MEF) to study the role of virus-induced autophagy and apoptosis, the cross-talk between both pathways, and their relation to IAV infection [ATCC strain A/Puerto Rico/8/34(H1N1) (hereafter; PR8)]. PR8-infected and mock-infected cells were analyzed by immunoblotting, immunofluorescence confocal microscopy, electron microscopy and flow cytometry (FACS). We found that PR8 infection simultaneously induced autophagy and apoptosis in A549 cells. Autophagy was associated with Bax and Bak activation, intrinsic caspase cleavage and subsequent PARP-1 and BID cleavage. Both Bax knockout (KO) and Bax/Bak double knockout MEFs displayed inhibition of virus-induced cytopathology and cell death and diminished virus-mediated caspase activation, suggesting that virus-induced apoptosis is Bax/Bak-dependent. Biochemical inhibition of autophagy induction with 3-methyladenine blocked both virus replication and apoptosis pathways. These effects were replicated using autophagy-refractory Atg3 KO and Atg5 KO cells. Taken together, our data indicate that PR8 infection simultaneously induces autophagy and Bax/caspase-dependent apoptosis, with autophagy playing a role to support PR8 replication, in part, by modulating virus-induced apoptosis.

Control of mitochondrial physiology and cell death by the Bcl-2 family proteins Bax and Bok

Neuronal cell death is often triggered by events that involve intracellular increases in Ca²⁺. Under resting conditions, the intracellular Ca²⁺ concentration is tightly controlled by a number of extrusion and sequestering mechanisms involving the plasma membrane, mitochondria, and ER. These mechanisms act to prevent a disruption of neuronal ion homeostasis. As these processes require ATP, excessive Ca²⁺ overloading may cause energy depletion, mitochondrial dysfunction, and may eventually lead to Ca²⁺-dependent cell death. Excessive Ca²⁺ entry though glutamate receptors (excitotoxicity) has been implicated in several neurologic and chronic neurodegenerative diseases, including ischemic stroke, epilepsy, and Alzheimer's disease. Recent evidence has revealed that excitotoxic cell death is regulated by the B-cell lymphoma-2 (Bcl-2) family of proteins. Bcl-2 proteins, comprising of both pro-apoptotic and anti-apoptotic members, have been shown to not only mediate the intrinsic apoptosis pathway by controlling mitochondrial outer membrane (MOM) integrity, but to also control neuronal Ca²⁺ homeostasis and energetics. In this review, the role of Bcl-2 family proteins in the regulation of apoptosis, their expression in the central nervous system and how they control Ca²⁺-dependent neuronal injury are summarized. We review the current knowledge on Bcl-2 family proteins in the regulation of mitochondrial function and bioenergetics, including the fusion and fission machinery, and their role in Ca²⁺ homeostasis regulation at the mitochondria and ER. Specifically, we discuss how the 'pro-apoptotic' Bcl-2 family proteins, Bax and Bok, physiologically expressed in the nervous system, regulate such 'non-apoptotic/daytime' functions.

Influence of microRNAs and Long Non-Coding RNAs in Cancer Chemoresistance

Innate and acquired chemoresistance exhibited by most tumours exposed to conventional chemotherapeutic agents account for the majority of relapse cases in cancer patients. Such chemoresistance phenotypes are of a multi-factorial nature from multiple key molecular players. The discovery of the RNA interference pathway in 1998 and the widespread gene regulatory influences exerted by microRNAs (miRNAs) and other non-coding RNAs have certainly expanded the level of intricacy present for the development of any single physiological phenotype, including cancer chemoresistance. This review article focuses on the latest research efforts in identifying and validating specific key molecular players from the two main families of non-coding RNAs, namely miRNAs and long non-coding RNAs (lncRNAs), having direct or indirect influences in the development of cancer drug resistance properties and how such knowledge can be utilised for novel theranostics in oncology.

Vagal nerve stimulation improves mitochondrial dynamics via an M3 receptor/CaMKKβ/AMPK pathway in isoproterenol-induced myocardial ischaemia

Mitochondrial dynamics-fission and fusion-are associated with ischaemic heart disease (IHD). This study explored the protective effect of vagal nerve stimulation (VNS) against isoproterenol (ISO)-induced myocardial ischaemia in a rat model and tested whether VNS plays a role in preventing disorders of mitochondrial dynamics and function. Isoproterenol not only caused cardiac injury but also increased the expression of mitochondrial fission proteins [dynamin-related peptide1 (Drp1) and mitochondrial fission protein1 (Fis-1)) and decreased the expression of fusion proteins (optic atrophy-1 (OPA1) and mitofusins1/2 (Mfn1/2)], thereby disrupting mitochondrial dynamics and leading to increase in mitochondrial fragments. Interestingly, VNS restored mitochondrial dynamics through regulation of Drp1, Fis-1, OPA1 and Mfn1/2; enhanced ATP content and mitochondrial membrane potential; reduced mitochondrial permeability transition pore (MPTP) opening; and improved mitochondrial ultrastructure and size. Furthermore, VNS reduced the size of the myocardial infarction and ameliorated cardiomyocyte apoptosis and cardiac dysfunction induced by ISO. Moreover, VNS activated AMP-activated protein kinase (AMPK), which was accompanied by phosphorylation of Ca2+ /calmodulin-dependent protein kinase kinase β (CaMKKβ) during myocardial ischaemia. Treatment with subtype-3 of muscarinic acetylcholine receptor (M3 R) antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide or AMPK inhibitor Compound C abolished the protective effects of VNS on mitochondrial dynamics and function, suggesting that M3 R/CaMKKβ/AMPK signalling are involved in mediating beneficial effects of VNS. This study demonstrates that VNS modulates mitochondrial dynamics and improves mitochondrial function, possibly through the M3 R/CaMKKβ/AMPK pathway, to attenuate ISO-induced cardiac damage in rats. Targeting mitochondrial dynamics may provide a novel therapeutic strategy in IHD.

MicroRNA-135a Regulates Apoptosis Induced by Hydrogen Peroxide in Rat Cardiomyoblast Cells

Oxidative stress and apoptosis are the most important pathologic features of ischemic heart disease. Recent research has indicated that microRNAs (miRs) play an essential role in apoptosis. However, whether miRs might regulate B cell lymphoma-2 (Bcl-2) protein in apoptosis during ischemic heart disease is still unclear. The aim of this study, therefore, was to confirm the regulation of microRNA-135a (miR-135a) in oxidative stress injuries induced by hydrogen peroxide (H2O2) in rat cardiomyoblast cells H9c2. To this end, we analyzed the effects of H2O2 treatment on miR-135a expression in rat cardiomyocytes. Furthermore, we upregulated and inhibited miR-135a using mimics and inhibitors, respectively, and examined the effects on cell viability and apoptosis-related proteins. We observed that miR-135a was markedly up-regulated under H2O2 treatment in rat cardiomyoblast cells. Overexpression of miR-135a blocked the Bcl-2 protein and enhanced the apoptosis induced by H2O2, and miR-135a inhibition restored Bcl-2 protein expression. Interestingly, miR-135a inhibition did not attenuate H2O2-induced apoptosis with Bcl-2 knockdown. The results of the present study indicate that miR-135a regulates H2O2-induced apoptosis in H9c2 cells via targeting Bcl-2, and that miR-135a may be a novel therapeutic target for ischemic heart disease.

Crude extract of Euphorbia formosana induces apoptosis of DU145 human prostate cancer cells acts through the caspase-dependent and independent signaling pathway

Prostate cancer is the most frequently diagnosed malignancy in men and the second highest contributor of male cancer mortality. The crude extract of Euphorbia formosana (CEEF) has been used for treatment of different diseases but the cytotoxic effects of CEEF on human cancer cells have not been reported. The purpose of the present experiments was to determine effects of CEEF on cell cycle distribution and induction of apoptosis in DU145 human prostate cancer cells in vitro. Contrast-phase microscope was used for examining cell morphological changes. Flow cytometric assays were used for cell viability, cell cycle, apoptosis, reactive oxygen species, and Ca²⁺ production and mitochondria membrane potential (ΔΨ_m ). Western blotting was used for examining protein expression of cell cycle and apoptosis associated proteins. Real-time PCR was used for examining mRNA levels of caspase-3, -8, and -9, AIF, and Endo G. Confocal laser microscope was used to examine the translocation of AIF, Endo G, and cytochrome in DU145 cells after CEEF exposure. CEEF-induced cell morphological changes, decreased the percentage of viable cells, and induced S phase arrest and apoptosis in DU145 cells. Furthermore, CEEF promoted RAS and Ca²⁺ production and reduced ΔΨ_m levels. Real-time QPCR confirmed that CEEF promoted the mRNA expression of caspase-3 and -9, AIF and Endo G and we found that AIF and Endo G and cytochrome c were released from mitochondria. Taken together, CEEF-induced cytotoxic effects via ROS production, induced S phase arrest and induction of apoptosis through caspase-dependent and independent and mitochondria-dependent pathways in DU245 cancer cells. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1600-1611, 2016.

Neuroprotective effects of lotus seedpod procyanidins on extremely low frequency electromagnetic field-induced neurotoxicity in primary cultured hippocampal neurons

The present study investigated the protective effects of lotus seedpod procyanidins (LSPCs) on extremely low frequency electromagnetic field (ELF-EMF)-induced neurotoxicity in primary cultured rat hippocampal neurons and the underlying molecular mechanism. The results of MTT, morphological observation, superoxide dismutase (SOD) and malondialdehyde (MDA) assays showed that compared with control, incubating neurons under ELF-EMF exposure significantly decreased cell viability and increased the number of apoptotic cells, whereas LSPCs evidently protected the hippocampal neurons against ELF-EMF-induced cell damage. Moreover, a certain concentration of LSPCs inhibited the elevation of intracellular reactive oxygen species (ROS) and Ca(2+) level, as well as prevented the disruption of mitochondrial membrane potential induced by ELF-EMF exposure. In addition, supplementation with LSPCs could alleviate DNA damage, block cell cycle arrest at S phase, and inhibit apoptosis and necrosis of hippocampal neurons under ELF-EMF exposure. Further study demonstrated that LSPCs up-regulated the activations of Bcl-2, Bcl-xl proteins and suppressed the expressions of Bad, Bax proteins caused by ELF-EMF exposure. In conclusion, these findings revealed that LSPCs protected against ELF-EMF-induced neurotoxicity through inhibiting oxidative stress and mitochondrial apoptotic pathway.

Zfra activates memory Hyal-2+ CD3- CD19- spleen cells to block cancer growth, stemness, and metastasis in vivo

Zfra is a 31-amino-acid zinc finger-like protein, which participates in the tumor necrosis factor signaling. Here, we determined that when nude mice and BALB/c mice were pre-injected with nanogram levels of a synthetic Zfra1–31 or truncated Zfra4–10 peptide via tail veins, these mice became resistant to the growth, metastasis and stemness of melanoma cells, and many malignant cancer cells. The synthetic peptides underwent self-polymerization in phosphate-buffered saline. Alteration of the Ser8 phosphorylation site to Gly8 abolished Zfra aggregation and its-mediated cancer suppression in vivo. Injected Zfra peptide autofluoresced due to polymerization and was trapped mainly in the spleen. Transfer of Zfra-stimulated spleen cells to naïve mice conferred resistance to cancer growth. Zfra-binding cells, designated Hyal-2+ CD3− CD19− Z cells, are approximately 25–30% in the normal spleen, but are significantly downregulated (near 0–3%) in tumor-growing mice. Zfra prevented the loss of Z cells caused by tumors. In vitro stimulation or education of naïve spleen cells with Zfra allowed generation of activated Z cells to confer a memory anticancer response in naïve or cancer-growing mice. In particular, Z cells are abundant in nude and NOD-SCID mice, and can be readily activated by Zfra to mount against cancer growth.

Mitochondrial fusion/fission dynamics in neurodegeneration and neuronal plasticity

Mitochondria are dynamic organelles that continually move, fuse and divide. The dynamic balance of fusion and fission of mitochondria determines their morphology and allows their immediate adaptation to energetic needs, keeps mitochondria in good health by restoring or removing damaged organelles or precipitates cells in apoptosis in cases of severe defects. Mitochondrial fusion and fission are essential in mammals and their disturbances are associated with several diseases. However, while mitochondrial fusion/fission dynamics, and the proteins that control these processes, are ubiquitous, associated diseases are primarily neurological disorders. Accordingly, inactivation of the main actors of mitochondrial fusion/fission dynamics is associated with defects in neuronal development, plasticity and functioning, both ex vivo and in vivo. Here, we present the central actors of mitochondrial fusion and fission and review the role of mitochondrial dynamics in neuronal physiology and pathophysiology. Particular emphasis is placed on the three main actors of these processes i.e. DRP1,MFN1-2, and OPA1 as well as on GDAP1, a protein of the mitochondrial outer membrane preferentially expressed in neurons. This article is part of a Special Issue entitled: Mitochondria & Brain.

MiR-181a influences the cognitive function of epileptic rats induced by pentylenetetrazol

Our previous study showed that the expression of miR-181a in memory impairment group of pentylenetetrazol (PTZ)-induced epileptic rats was up-regulated, but whether miR-181a influenced the cognitive function of PTZ-induced epileptic rats remains unknown. Therefore, we investigated the role of miR-181a in the cognitive function of PTZ-induced epileptic rats. A model of temporal lobe epilepsy (TLE) was induced via PTZ kindling in SD male rats. The epileptic rats were divided into Epilepsy group, Agomir-control group, miR-181a agomir group, 12 rats for each. 12 rats were used as sham group. We found that compared to the sham group, the expression of miR-181a in the Epilepsy group was increased. We also found that escape latency in the 5th day was prolonged and crossing times in the 6th day was reduced via Morris Water Maze test, which may indicate memory impairment. Furthermore, over-expression of miR-181a effectively reduced Bcl-2 protein level and increased apoptosis in hippocampus. Moreover, compared with Agomir-control group, the escape latency of miR-181a agomir group was obviously induced (P<0.05). Our findings suggest that miR-181a may play a role in impairing the cognitive function of PTZ-induced epileptic rats, and miR-181a could decrease the Bcl-2 protein and induce the apoptosis in the hippocampus that might be the way to impair cognitive function.

The Toll-Like Receptor 5 Agonist Entolimod Mitigates Lethal Acute Radiation Syndrome in Non-Human Primates

There are currently no approved medical radiation countermeasures (MRC) to reduce the lethality of high-dose total body ionizing irradiation expected in nuclear emergencies. An ideal MRC would be effective even when administered well after radiation exposure and would counteract the effects of irradiation on the hematopoietic system and gastrointestinal tract that contribute to its lethality. Entolimod is a Toll-like receptor 5 agonist with demonstrated radioprotective/mitigative activity in rodents and radioprotective activity in non-human primates. Here, we report data from several exploratory studies conducted in lethally irradiated non-human primates (rhesus macaques) treated with a single intramuscular injection of entolimod (in the absence of intensive individualized supportive care) administered in a mitigative regimen, 1-48 hours after irradiation. Following exposure to LD50-70/40 of radiation, injection of efficacious doses of entolimod administered as late as 25 hours thereafter reduced the risk of mortality 2-3-fold, providing a statistically significant (P<0.01) absolute survival advantage of 40-60% compared to vehicle treatment. Similar magnitude of survival improvement was also achieved with drug delivered 48 hours after irradiation. Improved survival was accompanied by predominantly significant (P<0.05) effects of entolimod administration on accelerated morphological recovery of hematopoietic and immune system organs, decreased severity and duration of thrombocytopenia, anemia and neutropenia, and increased clonogenic potential of the bone marrow compared to control irradiated animals. Entolimod treatment also led to reduced apoptosis and accelerated crypt regeneration in the gastrointestinal tract. Together, these data indicate that entolimod is a highly promising potential life-saving treatment for victims of radiation disasters.

The Drosophila retinoblastoma protein, Rbf1, induces a Debcl- and Drp1-dependent mitochondrial apoptosis

In accordance with its tumor suppressor role, the retinoblastoma protein pRb can ensure pro-apoptotic functions. Rbf1, the Drosophila homolog of Rb, also displays a pro-apoptotic activity in proliferative cells. We have previously shown that the Rbf1 pro-apoptotic activity depends on its ability to decrease the level of anti-apoptotic proteins such as the Bcl-2 family protein Buffy. Buffy often acts in an opposite manner to Debcl, the other Drosophila Bcl-2-family protein. Both proteins can localize at the mitochondrion, but the way they control apoptosis still remains unclear. Here, we demonstrate that Debcl and the pro-fission gene Drp1 are necessary downstream of Buffy to trigger a mitochondrial fragmentation during Rbf1-induced apoptosis. Interestingly, Rbf1-induced apoptosis leads to a Debcl- and Drp1-dependent reactive oxygen species production, which in turn activates the Jun Kinase pathway to trigger cell death. Moreover, we show that Debcl and Drp1 can interact and that Buffy inhibits this interaction. Notably, Debcl modulates Drp1 mitochondrial localization during apoptosis. These results provide a mechanism by which Drosophila Bcl-2 family proteins can control apoptosis, and shed light on a link between Rbf1 and mitochondrial dynamics in vivo.

Poly(ADP-ribosylation) and neurodegenerative disorders

Impaired mitochondrial structure and function are common features of neurodegenerative disorders, ultimately characterized by the death of neural cells promoted by still unknown signals. Among the possible modulators of neurodegeneration, the activation of poly(ADP-ribosylation), a post-translational modification of proteins, has been considered, being the product of the reaction, poly(ADP-ribose), a signaling molecule for different cell death paradigms. The basic properties of poly(ADP-ribosylation) are here described, focusing on the mitochondrial events; cell death paradigms such as apoptosis, parthanatos, necroptosis and mitophagy are illustrated. Finally, the promising use of poly(ADP-ribosylation) inhibitors to rescue neurodegeneration is addressed.

MicroRNA-181c targets Bcl-2 and regulates mitochondrial morphology in myocardial cells

Apoptosis is an important mechanism for the development of heart failure. Mitochondria are central to the execution of apoptosis in the intrinsic pathway. The main regulator of mitochondrial pathway of apoptosis is Bcl-2 family which includes pro- and anti-apoptotic proteins. MicroRNAs are small noncoding RNA molecules that regulate gene expression by inhibiting mRNA translation and/or inducing mRNA degradation. It has been proposed that microRNAs play critical roles in the cardiovascular physiology and pathogenesis of cardiovascular diseases. Our previous study has found that microRNA-181c, a miRNA expressed in the myocardial cells, plays an important role in the development of heart failure. With bioinformatics analysis, we predicted that miR-181c could target the 3' untranslated region of Bcl-2, one of the anti-apoptotic members of the Bcl-2 family. Thus, we have suggested that miR-181c was involved in regulation of Bcl-2. In this study, we investigated this hypothesis using the Dual-Luciferase Reporter Assay System. Cultured myocardial cells were transfected with the mimic or inhibitor of miR-181c. We found that the level of miR-181c was inversely correlated with the Bcl-2 protein level and that transfection of myocardial cells with the mimic or inhibitor of miR-181c resulted in significant changes in the levels of caspases, Bcl-2 and cytochrome C in these cells. The increased level of Bcl-2 caused by the decrease in miR-181c protected mitochondrial morphology from the tumour necrosis factor alpha-induced apoptosis.

Inhibitory effects of 2-iodohexadecanal on FRTL-5 thyroid cells proliferation

Although thyroid gland function is mainly under the control of pituitary TSH, other factors, such as iodine, play a role in this process. The thyroid is capable of producing different iodolipids such as 6-iodo-deltalactone and 2-iodohexadecanal (2-IHDA). It was shown that these iodolipids mimic some of the inhibitory effects of excess iodide on several thyroid parameters.

OBJECTIVES

To study the effect of 2-IHDA on cell proliferation and apoptosis in FRTL-5 cells.

RESULTS

FRTL-5 cells were grown in the presence of TSH and treated with increasing concentrations of KI and 2-IHDA (0.5, 5, 10 and 33 µM) for 24, 48 and 72 h. Whereas KI inhibited cell proliferation only at 33 µM after 72 h of treatment, 2-IHDA inhibited in a time and concentration dependent manner. Analysis of cell cycle by flow cytometric DNA analysis revealed an accumulation of cells in G1 phase induced by 2-IHDA. The expression of cyclin A, cyclin D1 and cyclin D3 were reduced after treatment with 2-IHDA whereas CDK4 and CDK6 proteins were not modified. 2-IHDA induced a dynamic change in cytoplasmic to nuclear accumulation of p21 and p27 causing these proteins to be accumulated mostly in the nucleus. We also observed evidence of a pro-apoptotic effect of 2-IHDA at highest concentrations. No significant effect of KI was observed.

CONCLUSION

These results suggest that the inhibitory effects of 2-IHDA on FRTL-5 thyroid cell proliferation are mediated by cell cycle arrest in G1/S phase and cell death by apoptosis.

Mitochondria-mediated apoptosis in mammals

The mitochondria-mediated caspase activation pathway is a major apoptotic pathway characterized by mitochondrial outer membrane permeabilization (MOMP) and subsequent release of cytochrome c into the cytoplasm to activate caspases. MOMP is regulated by the Bcl-2 family of proteins. This pathway plays important roles not only in normal development, maintenance of tissue homeostasis and the regulation of immune system, but also in human diseases such as immune disorders, neurodegeneration and cancer. In the past decades the molecular basis of this pathway and the regulatory mechanism have been comprehensively studied, yet a great deal of new evidence indicates that cytochrome c release from mitochondria does not always lead to irreversible cell death, and that caspase activation can also have non-death functions. Thus, many unsolved questions and new challenges are still remaining. Furthermore, the dysfunction of this pathway involved in cancer development is obvious, and targeting the pathway as a therapeutic strategy has been extensively explored, but the efficacy of the targeted therapies is still under development. In this review we will discuss the mitochondria-mediated apoptosis pathway and its physiological roles and therapeutic implications.

Pyrroloquinoline Quinone Induces Cancer Cell Apoptosis via Mitochondrial-Dependent Pathway and Down-Regulating Cellular Bcl-2 Protein Expression

Pyrroloquinoline quinone (PQQ) has been reported as a promising agent that might contribute to tumor cell apoptosis and death, yet little is known on its mechanisms. In current study, the effect of PQQ on cell proliferation and mitochondrial-dependent apoptosis were examined in 3 solid tumor cell lines (A549, Neuro-2A and HCC-LM3). PQQ treatment at low to medium dosage exhibited potent anti-tumor activity on A549 and Neuro-2A cells, while had comparably minimal impact on the viabilities of 2 human normal cell lines (HRPTEpiC and HUVEC). The apoptosis of the 3 tumor cell lines induced by PQQ were increased in a concentration-dependent manner, which might be attributed to the accumulation of intracellular reactive oxygen species (ROS), decline in ATP levels and dissipation of mitochondrial membrane potential (MMP), in conjunction with down-regulation of Bcl-2 protein expression, up-regulation of activated caspase-3, and disturbed phosphorylated MAPK protein levels. PQQ induced tumor cells apoptosis was significantly alleviated by pan-caspase inhibitor Z-VAD-FMK. The present work highlights the potential capability of PQQ as an anti-tumor agent with low toxicity towards normal cells through activating mitochondrial-dependent apoptosis pathways, and warrants its development for cancer therapy.

Enhancement of mitochondrial ATP production by the Escherichia coli cytotoxic necrotizing factor 1

Mitochondria are dynamic organelles that constantly change shape and structure in response to different stimuli and metabolic demands of the cell. The Escherichia coli protein toxin cytotoxic necrotizing factor 1 (CNF1) has recently been reported to influence mitochondrial activity in a mouse model of Rett syndrome and to increase ATP content in the brain tissue of an Alzheimer's disease mouse model. In the present work, the ability of CNF1 to influence mitochondrial activity was investigated in IEC-6 normal intestinal crypt cells. In these cells, the toxin was able to induce an increase in cellular ATP content, probably due to an increment of the mitochondrial electron transport chain. In addition, the CNF1-induced Rho GTPase activity also caused changes in the mitochondrial architecture that mainly consisted in the formation of a complex network of elongated mitochondria. The involvement of the cAMP-dependent protein kinase A signaling pathway was postulated. Our results demonstrate that CNF1 positively affects mitochondria by bursting their energetic function and modifying their morphology.

Antipsychotic drug-associated gene-miRNA interaction in T-lymphocytes

Antipsychotic drugs (APDs) can have a profound effect on the human body that extends well beyond our understanding of their neuropsychopharmacology. Some of these effects manifest themselves in peripheral blood lymphocytes, and in some cases, particularly in clozapine treatment, result in serious complications. To better understand the molecular biology of APD action in lymphocytes, we investigated the influence of chlorpromazine, haloperidol and clozapine in vitro, by microarray-based gene and microRNA (miRNA) expression analysis. JM-Jurkat T-lymphocytes were cultured in the presence of the APDs or vehicle alone over 2 wk to model the early effects of APDs on expression. Interestingly both haloperidol and clozapine appear to regulate the expression of a large number of genes. Functional analysis of APD-associated differential expression revealed changes in genes related to oxidative stress, metabolic disease and surprisingly also implicated pathways and biological processes associated with neurological disease consistent with current understanding of the activity of APDs. We also identified miRNA-mRNA interaction associated with metabolic pathways and cell death/survival, all which could have relevance to known side effects of APDs. These results indicate that APDs have a significant effect on expression in peripheral tissue that relate to both known mechanisms as well as poorly characterized side effects.

Triggering receptor expressed on myeloid cells 1 (TREM-1)-mediated Bcl-2 induction prolongs macrophage survival

Triggering receptor expressed on myeloid cells 1 (TREM-1) is a superimmunoglobulin receptor expressed on myeloid cells that plays an important role in the amplification of inflammation. Recent studies suggest a role for TREM-1 in tumor-associated macrophages with relationship to tumor growth and progression. Whether the effects of TREM-1 on inflammation and tumor growth are mediated by an alteration in cell survival signaling is not known. In these studies, we show that TREM-1 knock-out macrophages exhibit an increase in apoptosis of cells in response to lipopolysaccharide (LPS) suggesting a role for TREM-1 in macrophage survival. Specific ligation of TREM-1 with monoclonal TREM-1 (mTREM-1) or overexpression of TREM-1 with adeno-TREM-1 induced B-cell lymphoma-2 (Bcl-2) with depletion of the key executioner caspase-3 prevents the cleavage of poly(ADP-ribose) polymerase. TREM-1 knock-out cells showed lack of induction of Bcl2 with an increase in caspase-3 activation in response to lipopolysaccharide. In addition overexpression of TREM-1 with adeno-TREM-1 led to an increase in mitofusins (MFN1 and MFN2) and knockdown of TREM-1 decreased the expression of mitofusins suggesting that TREM-1 contributes to the maintenance of mitochondrial integrity favoring cell survival. Investigations into potential mechanisms by which TREM-1 alters cell survival showed that TREM-1-induced Bcl-2 in an Egr2-dependent manner. Furthermore, our data shows that expression of Egr2 in response to specific ligation of TREM-1 is ERK mediated. These data for the first time provide novel mechanistic insights into the role of TREM-1 as an anti-apoptotic protein that prolongs macrophage survival.

Hypoxic VDAC1: a potential mitochondrial marker for cancer therapy

Finding new therapeutic targets to fight cancer is an ongoing quest. Because of insufficiencies in tumor vasculature, cells often are exposed to a hostile microenvironment that is low in oxygen (hypoxic) and nutrients. Thus, tumor cells face the challenge of finding new sources of energy and defying apoptosis, which allow them to survive, grow, and colonize other tissues. Eradicating specifically these hypoxic cells is one of the many goals of anticancer therapies. The mitochondrial voltage-dependent anion channel (VDAC) is a protein at the crossroads of metabolic and survival pathways. As its name suggests, VDAC is involved in ion transport as well as adenosine triphosphate and NAD(+) transport. We recently reported the presence in tumor cells of a novel hypoxia-induced form of VDAC. This form, a C-terminal truncated protein (VDAC1-ΔC), was associated in some cancer cell lines with a high output of adenosine triphosphate and a strong resistance to chemotherapy-induced apoptosis. Furthermore, VDAC1-ΔC was detected in tissues of 50 % of 46 patients with lung cancer. This review examines the significance of this new form of VDAC1 for anticancer therapy.

Diversity of cell death pathways: insight from the fly ovary

Multiple types of cell death exist including necrosis, apoptosis, and autophagic cell death. The Drosophila ovary provides a valuable model to study the diversity of cell death modalities, and we review recent progress to elucidate these pathways. At least five distinct types of cell death occur in the ovary, and we focus on two that have been studied extensively. Cell death of mid-stage egg chambers occurs through a novel caspase-dependent pathway that involves autophagy and triggers phagocytosis by surrounding somatic epithelial cells. For every egg, 15 germline nurse cells undergo developmental programmed cell death, which occurs independently of most known cell death genes. These forms of cell death are strikingly similar to cell death observed in the germlines of other organisms.

The structure of the caspase recruitment domain of BinCARD reveals that all three cysteines can be oxidized

The caspase recruitment domain (CARD) is present in death-domain superfamily proteins involved in inflammation and apoptosis. BinCARD is named for its ability to interact with Bcl10 and inhibit downstream signalling. Human BinCARD is expressed as two isoforms that encode the same N-terminal CARD region but which differ considerably in their C-termini. Both isoforms are expressed in immune cells, although BinCARD-2 is much more highly expressed. Crystals of the CARD fold common to both had low symmetry (space group P1). Molecular replacement was unsuccessful in this low-symmetry space group and, as the construct contains no methionines, first one and then two residues were engineered to methionine for MAD phasing. The double-methionine variant was produced as a selenomethionine derivative, which was crystallized and the structure was solved using data measured at two wavelengths. The crystal structures of the native and selenomethionine double mutant were refined to high resolution (1.58 and 1.40 Å resolution, respectively), revealing the presence of a cis-peptide bond between Tyr39 and Pro40. Unexpectedly, the native crystal structure revealed that all three cysteines were oxidized. The mitochondrial localization of BinCARD-2 and the susceptibility of its CARD region to redox modification points to the intriguing possibility of a redox-regulatory role.

6 Iodo-δ-lactone: a derivative of arachidonic acid with antitumor effects in HT-29 colon cancer cells

BACKGROUND

IL-δ (5-hydroxy-6 iodo-8,11,14-eicosatrienoic delta lactone) an iodinated arachidonic acid (AA) derivative, is one of the iodolipids biosynthesized by the thyroid. Although IL-δ regulates several thyroid parameters such as cell proliferation and goiter growth it was found that this iodolipid inhibits the growth of other non thyroid cell lines.

OBJECTIVES

To study the effect of IL-δ on cell proliferation and apoptosis in the colon cancer cell line HT-29.

RESULTS

Treatment with IL-δ reduced cell viability in a concentration-dependent manner: 1μM 20%, 5μM 25%, 10μM 31%, 50μM 47% and caused a significant decrease of PCNA expression (25%). IL-δ had pro-apoptotic effects, evidenced by morphological features of programmed cell death such as pyknosis, karyorrhexis, cell shrinkage and cell blebbing observed by fluorescence microscopy, and an increase in caspase-3 activity and in Bax/Bcl-2 ratio (2.5 after 3h of treatment). Furthermore, IL-δ increased ROS production (30%) and lipid peroxidation levels (19%), suggesting that apoptosis could be a result of increased oxidative stress. A maximum increase in c-fos and c-jun protein expression in response to IL-δ was observed 1h after initiation of the treatment. IL-δ also induced a tumour growth delay of 70% compared to the control group in NIH nude mice implanted with HT-29 cells.

CONCLUSION

Our study shows that IL-δ inhibits cell growth and induces apoptosis in the colon cancer cell line, HT-29 and opens the possibility that IL-δ could be a potential useful chemotherapy agent.

Utilisation of nanoparticle technology in cancer chemoresistance

The implementation of cytotoxic chemotherapeutic drugs in the fight against cancer has played an invariably essential role for minimizing the extent of tumour progression and/or metastases in the patient and thus allowing for longer event free survival periods following chemotherapy. However, such therapeutics are nonspecific and bring with them dose-dependent cumulative adverse effects which can severely exacerbate patient suffering. In addition, the emergence of innate and/or acquired chemoresistance to the exposed cytotoxic agents undoubtedly serves to thwart effective clinical efficacy of chemotherapy in the cancer patient. The advent of nanotechnology has led to the development of a myriad of nanoparticle-based strategies with the specific goal to overcome such therapeutic hurdles in multiple cancer conditions. This paper aims to provide a brief overview and recollection of all the latest advances in the last few years concerning the application of nanoparticle technology to enhance the safe and effective delivery of chemotherapeutic agents to the tumour site, together with providing possible solutions to circumvent cancer chemoresistance in the clinical setting.

TAT-CC fusion protein depresses the oncogenicity of BCR-ABL in vitro and in vivo through interrupting its oligomerization

Chronic myeloid leukemia (CML) is a clonal hematologic malignancy characterized by the BCR-ABL protein. BCR-ABL is a constitutively active tyrosine kinase and plays a critical role in the pathogenesis of CML. Imatinib mesylate, a selective tyrosine kinase inhibitor, is effective in CML, but drug resistance and relapse occur. The coiled-coil (CC) domain located in BCR(1-72) mediates BCR-ABL tetramerization, which is essential for the activation of tyrosine kinase and transformation potential of BCR-ABL. CC domain is supposed to be a therapeutic target for CML. We purified a TAT-CC protein competively binding with the endogenous CC domain to reduce BCR-ABL kinase activity. We found that TAT-CC co-located and interacted with BCR-ABL in Ba/F3-p210 and K562 cells. It induced apoptosis and inhibited proliferation in these cells. It increased the sensitivity of these cells to imatinib and reduced the phosphorylation of BCR-ABL, CRKL and STAT5. We confirmed that TAT-CC could attenuate the oncogenicity of Ba/F3-p210 cells and diminish the volume of K562 solid tumor in mice. We conclude targeting the CC may provide a complementary therapy to inhibit BCR-ABL oncogenicity.