Mitochondrial outer membrane permeabilization during apoptosis: the innocent bystander scenario

Multifunctional Heterometallic IrIII -AuI Probes as Promising Anticancer and Antiangiogenic Agents

A new class of emissive cyclometallated IrIII -AuI complexes with a bis(diphenylphosphino) methanide bridging ligand was successfully synthesised from the diphosphino complex [Ir(N^C)2 (dppm)]+ (1). The different gold ancillary ligand, a triphenylphosphine (2), a chloride (3) or a thiocytosine (4) did not reveal any significant effect on the photophysical properties, which are mainly due to metal-to-ligand charge-transfer (3 MLCT) transitions based on IrIII . However, the AuI fragment, along with the ancillary ligand, seemed crucial for the bioactivity in A549 lung carcinoma cells versus endothelial cells. Both cell types display variable sensitivities to the complexes (IC50 =0.6-3.5 μM). The apoptotic pathway is activated in all cases, and paraptotic cell death seems to take place at initial stages in A549 cells. Species 2-4 showed at least dual lysosomal and mitochondrial biodistribution in A549 cells, with an initial lysosomal localisation and a possible trafficking process between both organelles with time. The bimetallic IrIII -AuI complexes disrupted the mitochondrial transmembrane potential in A549 cells and increased reactive oxygen species (ROS) generation and thioredoxin reductase (TrxR) inhibition in comparison with that displayed by the monometallic complex 1. Angiogenic activity assays performed in endothelial cells revealed the promising antimetastatic potential of 1, 2 and 4.

Mitochondrial fission and mitophagy are independent mechanisms regulating ischemia/reperfusion injury in primary neurons

Mitochondrial dynamics and mitophagy are constitutive and complex systems that ensure a healthy mitochondrial network through the segregation and subsequent degradation of damaged mitochondria. Disruption of these systems can lead to mitochondrial dysfunction and has been established as a central mechanism of ischemia/reperfusion (I/R) injury. Emerging evidence suggests that mitochondrial dynamics and mitophagy are integrated systems; however, the role of this relationship in the context of I/R injury remains unclear. To investigate this concept, we utilized primary cortical neurons isolated from the novel dual-reporter mitochondrial quality control knockin mice (C57BL/6-Gt(ROSA)26Sortm1(CAG-mCherry/GFP)Ganl/J) with conditional knockout (KO) of Drp1 to investigate changes in mitochondrial dynamics and mitophagic flux during in vitro I/R injury. Mitochondrial dynamics was quantitatively measured in an unbiased manner using a machine learning mitochondrial morphology classification system, which consisted of four different classifications: network, unbranched, swollen, and punctate. Evaluation of mitochondrial morphology and mitophagic flux in primary neurons exposed to oxygen-glucose deprivation (OGD) and reoxygenation (OGD/R) revealed extensive mitochondrial fragmentation and swelling, together with a significant upregulation in mitophagic flux. Furthermore, the primary morphology of mitochondria undergoing mitophagy was classified as punctate. Colocalization using immunofluorescence as well as western blot analysis revealed that the PINK1/Parkin pathway of mitophagy was activated following OGD/R. Conditional KO of Drp1 prevented mitochondrial fragmentation and swelling following OGD/R but did not alter mitophagic flux. These data provide novel evidence that Drp1 plays a causal role in the progression of I/R injury, but mitophagy does not require Drp1-mediated mitochondrial fission.

β-Glucan: A dual regulator of apoptosis and cell proliferation

β-Glucans are polysaccharides generally obtained from the cell wall of bacteria, fungi, yeasts, and aleurone layer of cereals. β-Glucans are polymers, with β-1,3 glucose as core linear structure, but they differ in their main branch length, linkages and branching patterns, giving rise to high and low-molecular-weight β-glucans. They are well-known cell response modifiers with immune-modulating, nutraceutical and health beneficial effects, including anticancer and pro-apoptotic properties. β-Glucan extracts have shown positive responses in controlling tumor cell proliferation and activation of the immune system. The immunomodulatory action of β-glucans enhances the host's antitumor defense against cancer. In consonance with the above, many studies have shown that β-glucan treatment leads to the induction of apoptotic death of cancer cells. The ability of β-glucans to stimulate apoptotic pathways or the proteins involved in apoptosis prompting a new domain in cancer therapy. β-glucan can be a potential therapeutic agent for the treatment of cancer. However, there is a need to legitimize the β-glucan type, as most of the studies include β-glucan from different sources having different physicochemical properties. The body of literature presented here focuses on the effects of β-glucan on immunomodulation, proliferation, cell death and the possible mechanisms and pathways involved in these processes.

Silver nanoparticle induced toxicity and cell death mechanisms in embryonic zebrafish cells

Cell death is the process that regulates homeostasis and biochemical changes in healthy cells. Silver nanoparticles (AgNPs) act as powerful cell death inducers through the disruption of cellular signalling functions. In this study, embryonic zebrafish cells (ZF4) were used as a potential early-stage aquatic model to evaluate the molecular and cell death mechanisms implicated in the toxicity of AgNPs and Ag⁺. Here, a low, medium, and high concentration (2.5, 5, and 10 μg mL^-1) of three different sizes of AgNPs (10, 30 and 100 nm) and ionic Ag⁺ (1, 1.5 and 2 μg mL^-1) were used to investigate whether the size of the nanomaterial, ionic form, and mass concentration were related to the activation of particular cell death mechanisms and/or induction of different signalling pathways. Changes in the physicochemical properties of the AgNPs were also assessed in the presence of complex medium (cell culture) and reference testing medium (ultra-pure water). Results demonstrated that AgNPs underwent dissolution, as well as changes in hydrodynamic size, zeta potential and polydispersity index in both tested media depending on particle size and concentration. Similarly, exposure dose played a key role in regulating the different cell death modalities (apoptosis, necrosis, autophagy), and the signalling pathways (repair mechanisms) in cells that were activated in the attempt to overcome the induced damage. This study contributes to the 3Rs initiative to replace, reduce and refine animal experimentation through the use of alternative models for nanomaterials assessment.

Death agonist antibody against TRAILR2/DR5/TNFRSF10B enhances birinapant anti-tumor activity in HPV-positive head and neck squamous cell carcinomas

Head and neck squamous cell carcinomas (HNSCC) induced by human papillomavirus (HPV) have increased recently in the US. However, the distinct alterations of molecules involved in the death pathways and drug effects targeting inhibitor of apoptosis proteins (IAPs) have not been extensively characterized in HPV(+) HNSCC cells. In this study, we observed the distinct genomic and expression alterations of nine genes involved in cell death in 55% HNSCC tissues, which were associated with HPV status, tumor staging, and anatomic locations. Expression of four genes was statistically correlated with copy number variation. A panel of HPV(+) HNSCC lines showed abundant TRAILR2 and IAP1 protein expression, but were not sensitive to IAP inhibitor birinapant alone, while combinatory treatment with TNFα or especially TRAIL enhanced this drug sensitivity. The death agonistic TRAILR2 antibody alone showed no cell inhibitory effects, whereas its combination with birinapant and/or TRAIL protein demonstrated additive or synergistic effects. We observed predominantly late apoptosis mode of cell death after combinatorial treatments, and pan-caspase (ZVAD) and caspase-8 (ZIETD) inhibitors attenuated treatment-induced cell death. Our genomic and expression data-driven study provides a framework for identifying relevant combinatorial therapies targeting death pathways in HPV(+) HNSCC and other squamous cancer types.

Pemafibrate Pretreatment Attenuates Apoptosis and Autophagy during Hepatic Ischemia-Reperfusion Injury by Modulating JAK2/STAT3β/PPARα Pathway

Hepatic ischemia-reperfusion injury (HIRI) is a common phenomenon in liver transplantation and liver surgery. This article is aimed at clarifying the role of pemafibrate in HIRI through JAK2/STAT3β/PPARα. In the experiment, we divided Balb/c into seven groups, namely, normal control (NC), Sham, PEM (1.0 mg/kg), IRI, IRI + PEM (0.1 mg/kg), IRI + PEM (0.5 mg/kg), and IRI + PEM (1.0 mg/kg). We used biochemical assay, histopathological evaluation, immunohistochemistry, RT-PCR and qRT-PCR, ELISA analysis, and other methods to determine the level of serum AST, ALT, IL-1β, and TNF-α in the liver at three time points (2 h, 8 h, and 24 h) after reperfusion of apoptosis factor, autophagy factor, and the JAK2/STAT3/PPARα content in tissues. Our experiment results showed that the pemafibrate can effectively reduce the level of hepatic IR injury. In addition, pemafibrate has anti-inflammatory, antiapoptotic, and antiautophagy effects, which are mediated by the JAK2/STAT3β/PPARα pathway.

Interferons at the crossroad of cell death pathways during gastrointestinal inflammation and infection

Interferons (IFNs) are pleiotropic immune-modulatory cytokines that are well known for their essential role in host defense against viruses, bacteria, and other pathogenic microorganisms. They can exert both, protective or destructive functions depending on the microorganism, the targeted tissue and the cellular context. Interferon signaling results in the induction of IFN-stimulated genes (ISGs) influencing different cellular pathways including direct anti-viral/anti-bacterial response, immune-modulation or cell death. Multiple pathways leading to host cell death have been described, and it is becoming clear that depending on the cellular context, IFN-induced cell death can be beneficial for both: host and pathogen. Accordingly, activation or repression of corresponding signaling mechanisms occurs during various types of infection but is also an important pathway for gastrointestinal inflammation and tissue damage. In this review, we summarize the role of interferons at the crossroad of various cell death pathways in the gut during inflammation and infection.

Cell Death and Inflammation: The Role of Mitochondria in Health and Disease

Mitochondria serve as a hub for a multitude of vital cellular processes. To ensure an efficient deployment of mitochondrial tasks, organelle homeostasis needs to be preserved. Mitochondrial quality control (MQC) mechanisms (i.e., mitochondrial dynamics, biogenesis, proteostasis, and autophagy) are in place to safeguard organelle integrity and functionality. Defective MQC has been reported in several conditions characterized by chronic low-grade inflammation. In this context, the displacement of mitochondrial components, including mitochondrial DNA (mtDNA), into the extracellular compartment is a possible factor eliciting an innate immune response. The presence of bacterial-like CpG islands in mtDNA makes this molecule recognized as a damaged-associated molecular pattern by the innate immune system. Following cell death-triggering stressors, mtDNA can be released from the cell and ignite inflammation via several pathways. Crosstalk between autophagy and apoptosis has emerged as a pivotal factor for the regulation of mtDNA release, cell’s fate, and inflammation. The repression of mtDNA-mediated interferon production, a powerful driver of immunological cell death, is also regulated by autophagy–apoptosis crosstalk. Interferon production during mtDNA-mediated inflammation may be exploited for the elimination of dying cells and their conversion into elements driving anti-tumor immunity.

Targeting the Mitochondrial Permeability Transition Pore to Prevent Age-Associated Cell Damage and Neurodegeneration

The aging process is associated with significant alterations in mitochondrial function. These changes in mitochondrial function are thought to involve increased production of reactive oxygen species (ROS), which over time contribute to cell death, senescence, tissue degeneration, and impaired tissue repair. The mitochondrial permeability transition pore (mPTP) is likely to play a critical role in these processes, as increased ROS activates mPTP opening, which further increases ROS production. Injury and inflammation are also thought to increase mPTP opening, and chronic, low-grade inflammation is a hallmark of aging. Nicotinamide adenine dinucleotide (NAD+) can suppress the frequency and duration of mPTP opening; however, NAD+ levels are known to decline with age, further stimulating mPTP opening and increasing ROS release. Research on neurodegenerative diseases, particularly on Parkinson's disease (PD) and Alzheimer's disease (AD), has uncovered significant findings regarding mPTP openings and aging. Parkinson's disease is associated with a reduction in mitochondrial complex I activity and increased oxidative damage of DNA, both of which are linked to mPTP opening and subsequent ROS release. Similarly, AD is associated with increased mPTP openings, as evidenced by amyloid-beta (Aβ) interaction with the pore regulator cyclophilin D (CypD). Targeted therapies that can reduce the frequency and duration of mPTP opening may therefore have the potential to prevent age-related declines in cell and tissue function in various systems including the central nervous system.

Tunable Electromechanical Nanopore Trap Reveals Populations of Peripheral Membrane Protein Binding Conformations

We demonstrate that a naturally occurring nanopore, the voltage-dependent anion channel (VDAC) of the mitochondrion, can be used to electromechanically trap and interrogate proteins bound to a lipid surface at the single-molecule level. Electromechanically probing α-synuclein (αSyn), an intrinsically disordered neuronal protein intimately associated with Parkinson's pathology, reveals wide variation in the time required for individual proteins to unbind from the same membrane surface. The observed distributions of unbinding times span up to 3 orders of magnitude and depend strongly on the lipid composition of the membrane; surprisingly, lipid membranes to which αSyn binds weakly are most likely to contain subpopulations in which electromechanically driven unbinding is very slow. We conclude that unbinding of αSyn from the membrane surface depends not only on membrane binding affinity but also on the conformation adopted by an individual αSyn molecule on the membrane surface.

The Role of PKM2 in Metabolic Reprogramming: Insights into the Regulatory Roles of Non-Coding RNAs

Pyruvate kinase is a key regulator in glycolysis through the conversion of phosphoenolpyruvate (PEP) into pyruvate. Pyruvate kinase exists in various isoforms that can exhibit diverse biological functions and outcomes. The pyruvate kinase isoenzyme type M2 (PKM2) controls cell progression and survival through the regulation of key signaling pathways. In cancer cells, the dimer form of PKM2 predominates and plays an integral role in cancer metabolism. This predominance of the inactive dimeric form promotes the accumulation of phosphometabolites, allowing cancer cells to engage in high levels of synthetic processing to enhance their proliferative capacity. PKM2 has been recognized for its role in regulating gene expression and transcription factors critical for health and disease. This role enables PKM2 to exert profound regulatory effects that promote cancer cell metabolism, proliferation, and migration. In addition to its role in cancer, PKM2 regulates aspects essential to cellular homeostasis in non-cancer tissues and, in some cases, promotes tissue-specific pathways in health and diseases. In pursuit of understanding the diverse tissue-specific roles of PKM2, investigations targeting tissues such as the kidney, liver, adipose, and pancreas have been conducted. Findings from these studies enhance our understanding of PKM2 functions in various diseases beyond cancer. Therefore, there is substantial interest in PKM2 modulation as a potential therapeutic target for the treatment of multiple conditions. Indeed, a vast plethora of research has focused on identifying therapeutic strategies for targeting PKM2. Recently, targeting PKM2 through its regulatory microRNAs, long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) has gathered increasing interest. Thus, the goal of this review is to highlight recent advancements in PKM2 research, with a focus on PKM2 regulatory microRNAs and lncRNAs and their subsequent physiological significance.

Autophagy restricts mitochondrial DNA damage-induced release of ENDOG (endonuclease G) to regulate genome stability

Genotoxic insult causes nuclear and mitochondrial DNA damages with macroautophagy/autophagy induction. The role of mitochondrial DNA (mtDNA) damage in the requirement of autophagy for nuclear DNA (nDNA) stability is unclear. Using site-specific DNA damage approaches, we show that specific nDNA damage alone does not require autophagy for repair unless in the presence of mtDNA damage. We provide evidence that after IR exposure-induced mtDNA and nDNA damages, autophagy suppression causes non-apoptotic mitochondrial permeability, by which mitochondrial ENDOG (endonuclease G) is released and translocated to nuclei to sustain nDNA damage in a TET (tet methylcytosine dioxygenase)-dependent manner. Furthermore, blocking lysosome function is sufficient to increase the amount of mtDNA leakage to the cytosol, accompanied by ENDOG-free mitochondrial puncta formation with concurrent ENDOG nuclear accumulation. We proposed that autophagy eliminates the mitochondria specified by mtDNA damage-driven mitochondrial permeability to prevent ENDOG-mediated genome instability. Finally, we showed that HBx, a hepatitis B viral protein capable of suppressing autophagy, also causes mitochondrial permeability-dependent ENDOG mis-localization in nuclei and is linked to hepatitis B virus (HBV)-mediated hepatocellular carcinoma development.Abbreviations: 3-MA: 3-methyladenine; 5-hmC: 5-hydroxymethylcytosine; ACTB: actin beta; ATG5: autophagy related 5; ATM: ATM serine/threonine kinase; DFFB/CAD: DNA fragmentation factor subunit beta; cmtDNA: cytosolic mitochondrial DNA; ConA: concanamycin A; CQ: chloroquine; CsA: cyclosporin A; Dox: doxycycline; DSB: double-strand break; ENDOG: endonuclease G; GFP: green fluorescent protein; Gy: gray; H2AX: H2A.X variant histone; HBV: hepatitis B virus; HBx: hepatitis B virus X protein; HCC: hepatocellular carcinoma; I-PpoI: intron-encoded endonuclease; IR: ionizing radiation; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MOMP: mitochondrial outer membrane permeability; mPTP: mitochondrial permeability transition pore; mtDNA: mitochondrial DNA; nDNA: nuclear DNA; 4-OHT: 4-hydroxytamoxifen; rDNA: ribosomal DNA; ROS: reactive oxygen species; SQSTM1/p62: sequestosome 1; TET: tet methylcytosine dioxygenase; TFAM: transcription factor A, mitochondrial; TOMM20: translocase of outer mitochondrial membrane 20; VDAC: voltage dependent anion channel.

Regulating Mitochondrial pH with Light and Implications for Chemoresistance

Chemoresistance is one of the major challenges for cancer treatment, more recently ascribed to defective mitochondrial outer membrane permeabilization (MOMP), significantly diminishing chemotherapeutic agent-induced apoptosis. A boron-dipyrromethene (BODIPY) chromophore-based triarylsulfonium photoacid generator (BD-PAG) was used to target mitochondria with the aim to regulate mitochondrial pH and further depolarize the mitochondrial membrane. Cell viability assays demonstrated the relative biocompatibility of BD-PAG in the dark while live cell imaging suggested high accumulation in mitochondria. Specific assays indicated that BD-PAG is capable of regulating mitochondrial pH with significant effects on mitochondrial membrane depolarization. Therapeutic tests using chlorambucil in combination with BD-PAG revealed a new strategy in chemoresistance suppression.

Uncoupling the Folding-Function Paradigm of Lytic Peptides to Deliver Impermeable Inhibitors of Intracellular Protein-Protein Interactions

Here, we describe the use of peptide backbone N-methylation as a new strategy to transform membrane-lytic peptides (MLPs) into cytocompatible intracellular delivery vehicles. The ability of lytic peptides to engage with cell membranes has been exploited for drug delivery to carry impermeable cargo into cells, but their inherent toxicity results in narrow therapeutic windows that limit their clinical translation. For most linear MLPs, a prerequisite for membrane activity is their folding at cell surfaces. Modification of their backbone with N-methyl amides inhibits folding, which directly correlates to a reduction in lytic potential but only minimally affects cell entry. We synthesized a library of N-methylated peptides derived from MLPs and conducted structure-activity studies that demonstrated the broad utility of this approach across different secondary structures, including both β-sheet and helix-forming peptides. Our strategy is highlighted by the delivery of a notoriously difficult class of protein-protein interaction inhibitors that displayed on-target activity within cells.

The role of cell signaling in the crosstalk between autophagy and apoptosis in the regulation of tumor cell survival in response to sorafenib and neratinib

The molecular mechanisms by which tumor cells survive or die following therapeutic interventions are complex. There are three broadly defined categories of cell death processes: apoptosis (Type I), autophagic cell death (Type II), and necrosis (Type III). In hematopoietic tumor cells, the majority of toxic stimuli cause these cells to undergo a death process called apoptosis; apoptosis specifically involves the cleavage of DNA into large defined pieces and their subsequent localization in vesicles. Thus, 'pure' apoptosis largely lacks inflammatory potential. In carcinomas, however, the mechanisms by which tumor cells ultimately die are considerably more complex. Although the machinery of apoptosis is engaged by toxic stimuli, other processes such as autophagy ("self-eating") and replicative cell death can lead to observations that do not simplistically correspond to any of the individual Type I-III formalized death categories. The 'hybrid' forms of cell death observed in carcinoma cells result in cellular materials being released into the extracellular space without packaging, which promotes inflammation, potentially leading to the accelerated re-growth of surviving tumor cells by macrophages. Drugs as single agents or in combinations can simultaneously initiate signaling via both apoptotic and autophagic pathways. Based on the tumor type and its oncogene drivers, as well as the drug(s) being used and the duration and intensity of the autophagosome signal, apoptosis and autophagy have the potential to act in concert to kill or alternatively that the actions of either pathway can act to suppress signaling by the other pathway. And, there also is evidence that autophagic flux, by causing lysosomal protease activation, with their subsequent release into the cytosol, can directly mediate killing. This review will discuss the interactive biology between apoptosis and autophagy in carcinoma cells. Finally, the molecular actions of the FDA-approved drugs neratinib and sorafenib, and how they enhance both apoptotic and toxic autophagic processes, alone or in combination with other agents, is discussed in a bench-to-bedside manner.

Zeaxanthin Induces Apoptosis via ROS-Regulated MAPK and AKT Signaling Pathway in Human Gastric Cancer Cells

BACKGROUND

Zeaxanthin, a carotenoid commonly found in plants, has a variety of biological functions including anti-cancer activity.

PURPOSE

This study aimed to investigate the potential mechanisms of zeaxanthin in human gastric cancer cells.

METHODS

CCK-8 assay was used to examine the cytotoxic effect of zeaxanthin on human gastric cancer cells. Flow cytometry was used to analyse AGS cell cycle distribution and apoptosis status. Western blot analysis was used to detect the expression levels of cycle-related proteins (Cyclin A, Cyclin B1, CDK1/2, p21, and p27), apoptosis-related proteins (Bcl-2, Bad, caspase-3, PARP), MAPK, AKT, STAT3, and NF-κB.

RESULTS

CCK-8 assay showed that zeaxanthin has obvious cytotoxic effects on 12 types of human gastric cancer cells, but no obvious toxic effect on normal cells. In addition, flow cytometry and Western blotting results showed that zeaxanthin induces apoptosis by reducing mitochondrial membrane potential; increasing Cytochrome C, Bax, cleaved-caspase-3 (cle-cas-3), and cleaved-PARP (cle-PARP) expression levels; and decreasing Bcl-2, pro-caspase-3 (pro-cas-3), and pro-PARP expression levels. Additionally, zeaxanthin caused cell cycle arrest at the G2/M phase by increasing the levels of p21 and p27 and reduced the levels of AKT, Cyclin A, Cyclin B1, and Cyclin-dependent kinase 1/2 (CDK1/2). Furthermore, after zeaxanthin treatment, the expression levels of reactive oxygen species (ROS), p-JNK, p-p38, and I-κB increased, and the expression levels of p-ERK, p-AKT, STAT3, and NF-κB decreased. However, the ROS scavenger N-acetylcysteine (NAC) and MAPK inhibitors inhibited zeaxanthin-induced apoptosis, and under the action of zeaxanthin, MAPK regulated NF-κB and STAT3, and reduced their protein expression levels.

CONCLUSION

Zeaxanthin has a potential effect against gastric cancer cells through the ROS-mediated MAPK, AKT, NF-κB, and STAT3 signaling pathways, and it is expected to become a new drug for the treatment of human gastric cancer.

Methylmercury-Mediated Oxidative Stress and Activation of the Cellular Protective System

Methylmercury (MeHg) is a well-known neurotoxicant that causes severe intoxication in humans. In Japan, it is referred to as Minamata disease, which involves two characteristic clinical forms: fetal type and adult type depending on the exposed age. In addition to MeHg burden level, individual susceptibility to MeHg plays a role in the manifestation of MeHg toxicity. Research progress has pointed out the importance of oxidative stress in the pathogenesis of MeHg toxicity. MeHg has a high affinity for selenohydryl groups, sulfhydryl groups, and selenides. It has been clarified that such affinity characteristics cause the impairment of antioxidant enzymes and proteins, resulting in the disruption of antioxidant systems. Furthermore, MeHg-induced intracellular selenium deficiency due to the greater affinity of MeHg for selenohydryl groups and selenides leads to failure in the recoding of a UGA codon for selenocysteine and results in the degradation of antioxidant selenoenzyme mRNA by nonsense-mediated mRNA decay. The defect of antioxidant selenoenzyme replenishment exacerbates MeHg-mediated oxidative stress. On the other hand, it has also been revealed that MeHg can directly activate the antioxidant Keap1/Nrf2 signaling pathway. This review summarizes the incidence of MeHg-mediated oxidative stress from the viewpoint of the individual intracellular redox system interactions and the MeHg-mediated aforementioned intracellular events. In addition, the mechanisms of cellular stress pathways and neuronal cell death triggered by MeHg-mediated oxidative stress and direct interactions of MeHg with reactive residues of proteins are mentioned.

Fluorescent spherical mesoporous silica nanoparticles loaded with emodin: Synthesis, cellular uptake and anticancer activity

The natural product emodin (EO) exhibits anti-inflammatory, antiangiogenesis and antineoplastic properties in vitro and in vivo. Due to its biological properties as well as its fluorescence, EO can be useful in pharmacology and pharmacokinetics. To enhance its selectivity to cancer cells, EO was loaded into non-fluorescent and novel fluorescent spherical mesoporous nanoparticles bearing N-methyl isatoic anhydride (SNM~M) or lissamine rhodamine B sulfonyl moieties (SNM~L). The propylamine functionalized mesoporous silica nanomaterial (SNM) were characterized by powder X-ray diffraction (XRD), nitrogen gas sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence spectroscopy, thermogravimetric analysis (TGA) and UV spectroscopy. The cytotoxicity of EO-loaded nanoparticles was tested against the human colon carcinoma cell line HT-29. Non-loaded SNM did not affect cell proliferation, whereas those loaded with EO were at least as efficient as EO alone. It could be shown by fluorescence microscopy that the uptake of silica nanomaterial by the tumor cells occurred within 2 h and the release of EO occurred within 48 h of treatment. Flow cytometry and Western blot analysis showed that SNM containing EO induced apoptosis in HT-29 cells.

Activation of forkhead box O3a by mono(2-ethylhexyl)phthalate and its role in protection against mono(2-ethylhexyl)phthalate-induced oxidative stress and apoptosis in human cardiomyocytes

Mono(2-ethylhexyl)phthalate (MEHP), the active metabolite of di(2-ethylhexyl)phthalate (DEHP), is known to exert cardiotoxicity. The aim of the present study was to investigate the role of forkhead box O3a (FOXO3a) in MEHP-induced human AC16 cardiomyocyte injuries. MEHP reduced cell viability and mitochondrial membrane potential (ΔΨm), whereas it increased lactate dehydrogenase (LDH) leakage, production of reactive oxygen species (ROS), and apoptosis in cardiomyocytes. The expression of FOXO3a and its target genes, mitochondrial superoxide dismutase (Mn-SOD) and apoptosis repressor with caspase recruitment domain (ARC), increased after MEHP exposure, but the expression of p-FOXO3a protein was decreased. Overexpression of FOXO3a decreased the production of ROS and the apoptosis rate induced by MEHP, and the expression of Mn-SOD and ARC was further increased after MEHP exposure. In contrast, knockdown of FOXO3a resulted in increased ROS production and apoptosis and suppressed the expression of Mn-SOD and ARC in the presence of MEHP. However, overexpression or knockdown of FOXO3a did not affect MEHP-induced loss of ΔΨm. In conclusion, the loss of ΔΨm and apoptosis are involved in MEHP-induced cardiomyocyte toxicity. Activation of FOXO3a defends against MEHP-induced oxidative stress and apoptosis by upregulating the expression of Mn-SOD and ARC in AC16 cardiomyocytes.

Enzymatic Noncovalent Synthesis

Enzymatic reactions and noncovalent (i.e., supramolecular) interactions are two fundamental nongenetic attributes of life. Enzymatic noncovalent synthesis (ENS) refers to a process where enzymatic reactions control intermolecular noncovalent interactions for spatial organization of higher-order molecular assemblies that exhibit emergent properties and functions. Like enzymatic covalent synthesis (ECS), in which an enzyme catalyzes the formation of covalent bonds to generate individual molecules, ENS is a unifying theme for understanding the functions, morphologies, and locations of molecular ensembles in cellular environments. This review intends to provide a summary of the works of ENS within the past decade and emphasize ENS for functions. After comparing ECS and ENS, we describe a few representative examples where nature uses ENS, as a rule of life, to create the ensembles of biomacromolecules for emergent properties/functions in a myriad of cellular processes. Then, we focus on ENS of man-made (synthetic) molecules in cell-free conditions, classified by the types of enzymes. After that, we introduce the exploration of ENS of man-made molecules in the context of cells by discussing intercellular, peri/intracellular, and subcellular ENS for cell morphogenesis, molecular imaging, cancer therapy, and other applications. Finally, we provide a perspective on the promises of ENS for developing molecular assemblies/processes for functions. This review aims to be an updated introduction for researchers who are interested in exploring noncovalent synthesis for developing molecular science and technologies to address societal needs.

Mitochondrial Cl--Selective Fluorescent Probe for Biological Applications

Herein we describe the development of the first mitochondrial Cl^--selective fluorescent probe, Mito-MQAE, and its applications in biological systems. Fluorescence of Mito-MQAE is insensitive to pH over the physiological pH range and is quenched by Cl^- with a Stern-Volmer quenching constant of 201 M^-1 at pH 7.0. The results of cell studies using Mito-MQAE show that substances with the ability to disrupt mitochondrial membranes cause increases in the mitochondrial Cl^- concentration.

Anti-breast cancer and toxicity studies of total secondary saponin from Anemone raddeana Rhizome on MCF-7 cells via ROS generation and PI3K/AKT/mTOR inactivation

ETHNOPHARMACOLOGICAL RELEVANCE

The rhizome of Anemone raddeana Regel (A. raddeana) is a famous traditional Chinese medicine (TCM) recorded in Chinese Pharmacopoeia for the treatment of carbuncle and swelling. Carbuncle swollen is an explanation of tumor in the theory of TCM and softening and resolving hard mass effects are one of the important pharmacological activities of A. raddeana.

AIM OF THE STUDY

We investigated the potential anti-breast cancer effect and toxicological properties of alkali-ethanol extract from A. raddeana, namely total secondary saponin (TSS).

MATERIALS AND METHODS

Anti-proliferative effect of total saponin of A. raddeana (ATS) and TSS were tested using MTT assay. Hoechst staining, flow cytometry analysis, DCFH-DA fluorescence microscopy and western blot were carried out to evaluate the mechanisms of action of TSS. The potential anti-breast cancer activity and toxicological properties of TSS were tested in vivo.

RESULTS

ATS and TSS could inhibit the proliferation of A549, HepG2, MCF-7, MDA-MB-231 and SKBr-3 cells, especially for MCF-7 cells. Flow cytometry analysis revealed that TSS (10, 12 and 15 μg/ml) could induce cell cycle arrest on G0/G1 phase and promote apoptosis of MCF-7 cells. TSS could increase Bax/Bcl-2 ratio, elevate cytochrome c levels in cytosol and activate caspase-3/9. In addition, TSS also induced ROS generation and inactivated PI3K/AKT/mTOR pathway which may involved in the mitochondrial dysfunction of MCF-7 cells. TSS showed slight toxic at the dosage of 100 and 200 mg/kg by oral administration without any toxic potential for 28 days. TSS (50, 100 and 200 mg/kg) showed significant inhibitory effect on growth of transplanted tumor in mice. At last, twenty-three C-3 monosaccharide oleanane-type triterpene saponins were tentatively identified, which may contributed to the anti-cancer activity of TSS.

CONCLUSION

This study demonstrated that TSS exhibited anti-proliferative and pro-apoptosis activities on MCF-7 cells via ROS-mediated activation of mitochondrial apoptosis pathway. TSS might be used as chemotherapeutic agent for the treatment of breast cancer with relatively low toxicity.

A steroidal saponin isolated from Allium chinense simultaneously induces apoptosis and autophagy by modulating the PI3K/Akt/mTOR signaling pathway in human gastric adenocarcinoma

Allium chinense, as a side dish on Asian table, is often used in folk medicine for its health benefits. (25R)-5α-spirostan-3β-yl-3-O-acetyl-O-β-d-glucopyranosyl-(1 → 2)-O-[β-d-glucopyranosyl-(1 → 3)]-O-β-d-glucopyranosyl-(1 → 4)-β-d-galactopyranoside (A-24) is a bioactive steroidal saponin isolated from Allium chinense. Previously, we have shown that A-24 has cytotoxic effects on cancer cells, but not on normal cells. To further explore the underlying mechanisms, in this study, we investigated the anticancer activity of A-24 in human gastric cancer cell lines in terms of cell proliferation, colony formation, cell cycle, induction of apoptosis/autophagy, and PI3K/Akt/mTOR pathway. A-24 showed dose-dependent cytotoxicity in SGC-7901 and AGS cell lines, it induced intrinsic mitochondrial pathway of apoptosis as well as autophagy, G2/M phase arrest and modulation of cyclinB1, p-cdc2, p-wee1 and p-Histone H3 expression. Furthermore, A-24 downregulated the phosphorylation of Akt at Ser473 and mTOR at Ser2448 in PI3K/Akt/mTOR pathway, and its downstream substrates p-p70S6K and p-4EBP1 in a dose-dependent manner. In addition, the pre-treatment of tumor cells with 3-methyladenine (3-MA) and LY294002 increased A-24-induced apoptosis. Collectively, these findings highlight the significance of downregulation of PI3K/Akt/mTOR pathway in A-24-induced apoptosis and autophagy, and the potential application of A-24 as a novel candidate in the treatment of human gastric adenocarcinoma.

MiR-7 mediates mitochondrial impairment to trigger apoptosis and necroptosis in Rhabdomyosarcoma

BACKGROUND

Rhabdomyosarcoma (RMS) is a pediatric cancer with rhabdomyoblastic phenotype and mitochondria act as pivotal regulators of its growth and progression. While miR-7-5p (miR-7) is reported to have a tumor-suppressive role, little is yet known about its antitumor activity in RMS.

METHODS

The effects of miR-7 on RMS were analyzed both in vitro and in vivo. Cell death modalities induced by miR-7 were identified. Influence on mitochondria was evaluated through RNA sequencing data, morphological observation and mitochondrial functional assays, including outer membrane permeability, bioenergetics and redox balance. Dual-luciferase assay and phenotype validation after transient gene silencing were performed to identify miR-7 targets in RMS.

RESULTS

MiR-7 executed anti-tumor effect in RMS beyond proliferation inhibition. Morphologic features and molecular characteristics with apoptosis and necroptosis were found in miR-7-transfected RMS cells. Chemical inhibitors of apoptosis and necroptosis were able to prevent miR-7-induced cell death. Further, we identified that mitochondrial impairment mainly contributed to these phenomena and mitochondrial proteins SLC25A37 and TIMM50 were crucial targets for miR-7 to induce cell death in RMS.

CONCLUSION

Our results extended the mechanism of miR-7 antitumor role in rhabdomyosarcoma cancer, and provided potential implications for its therapy.

The Role of Mitochondria in Systemic Lupus Erythematosus: A Glimpse of Various Pathogenetic Mechanisms

BACKGROUND

Systemic Lupus Erythematosus (SLE) is a polysystem autoimmune disease that adversely affects human health. Various organs can be affected, including the kidney or brain. Traditional treatment methods for SLE primarily rely on glucocorticoids and immunosuppressors. Unfortunately, these therapeutic agents cannot prevent a high recurrence rate after SLE remission. Therefore, novel therapeutic targets are urgently required.

METHODS

A systematic search of the published literature regarding the abnormal structure and function of mitochondria in SLE and therapies targeting mitochondria was performed in several databases.

RESULTS

Accumulating evidence indicates that mitochondrial dysfunction plays important roles in the pathogenesis of SLE, including influencing mitochondrial DNA damage, mitochondrial dynamics change, abnormal mitochondrial biogenesis and energy metabolism, mitophagy, oxidative stress, inflammatory reactions, apoptosis and NETosis. Further investigation of mitochondrial pathophysiological roles will result in further clarification of SLE. Specific lupus-induced organ damage also exhibits characteristic mitochondrial changes.

CONCLUSION

This review aimed to summarize the current research on the role of mitochondrial dysfunction in SLE, which will necessarily provide potential novel therapeutic targets for SLE.

Limited MOMP, ATM, and their roles in carcinogenesis and cancer treatment

Limited mitochondria outer membrane permeability (MOMP) is a novel biological process where mammalian cells initiate the intrinsic apoptosis pathway with increased mitochondrial permeability but survive. One of the major consequences of limited MOMP is apoptotic endonuclease-induced DNA double strand breaks. Recent studies indicate that these DNA double stand breaks and ensuing activation of DNA damage response factors such as ATM play important but previously underappreciated roles in carcinogenesis and tumor growth. Furthermore, novel non-canonical roles of DNA repair factors such as ATM in tumor growth and treatment are also emerging. In this review, we try to summarize recent findings on this newly revealed link between DNA double strand break repair and cell death pathways.

The Recombinant Fragment of Human κ-Casein Induces Cell Death by Targeting the Proteins of Mitochondrial Import in Breast Cancer Cells

Breast cancer is still one of the most common cancers for women. Specified therapeutics are indispensable for optimal treatment. In previous studies, it has been shown that RL2, the recombinant fragment of human κ-Casein, induces cell death in breast cancer cells. However, the molecular mechanisms of RL2-induced cell death remain largely unknown. In this study, mechanisms of RL2-induced cell death in breast cancer cells were systematically investigated. In particular, we demonstrate that RL2 induces loss of mitochondrial membrane potential and cellular ATP loss followed by cell death in breast cancer cells. The mass spectrometry-based screen for RL2 interaction partners identified mitochondrial import protein TOM70 as a target of RL2, which was subsequently validated. Further to this, we show that RL2 is targeted to mitochondria after internalization into the cells, where it can also be found in the dimeric form. The importance of TOM70 and RL2 interaction in RL2-induced reduction in ATP levels was validated by siRNA-induced downregulation of TOM70, resulting in the partial rescue of ATP production. Taken together, this study demonstrates that RL2–TOM70 interaction plays a key role in RL2-mediated cell death and targeting this pathway may provide new therapeutic options for treating breast cancer.

Astrocyte swelling in hepatic encephalopathy: molecular perspective of cytotoxic edema

Hepatic encephalopathy (HE) may occur in patients with liver failure. The most critical pathophysiologic mechanism of HE is cerebral edema following systemic hyperammonemia. The dysfunctional liver cannot eliminate circulatory ammonia, so its plasma and brain levels rise sharply. Astrocytes, the only cells that are responsible for ammonia detoxification in the brain, are dynamic cells with unique phenotypic properties that enable them to respond to small changes in their environment. Any pathological changes in astrocytes may cause neurological disturbances such as HE. Astrocyte swelling is the leading cause of cerebral edema, which may cause brain herniation and death by increasing intracranial pressure. Various factors may have a role in astrocyte swelling. However, the exact molecular mechanism of astrocyte swelling is not fully understood. This article discusses the possible mechanisms of astrocyte swelling which related to hyperammonia, including the possible roles of molecules like glutamine, lactate, aquaporin-4 water channel, 18 KDa translocator protein, glial fibrillary acidic protein, alanine, glutathione, toll-like receptor 4, epidermal growth factor receptor, glutamate, and manganese, as well as inflammation, oxidative stress, mitochondrial permeability transition, ATP depletion, and astrocyte senescence. All these agents and factors may be targeted in therapeutic approaches to HE.

Retinoprotection by BGP-15, a Hydroximic Acid Derivative, in a Type II Diabetic Rat Model Compared to Glibenclamide, Metformin, and Pioglitazone

High blood glucose and the consequential ischemia-reperfusion (I/R) injury damage vessels of the retina, deteriorating its function, which can be clearly visualized by electroretinography (ERG). The aim of the present study was to evaluate the possible retinoprotective effects of systemic BGP-15, an emerging drug candidate, in an insulin resistant animal model, the Goto-Kakizaki rat, and compare these results with well-known anti-diabetics such as glibenclamide, metformin, and pioglitazone, which even led to some novel conclusions about these well-known agents. Experiments were carried out on diseased animal model (Goto-Kakizaki rats). The used methods include weight measurement, glucose-related measurements—like fasting blood sugar analysis, oral glucose tolerance test, hyperinsulinemic euglycemic glucose clamp (HEGC), and calculations of different indices from HEGC results—electroretinography and Western Blot. Beside its apparent insulin sensitization, BGP-15 was also able to counteract the retina-damaging effect of Type II diabetes comparable to the aforementioned anti-diabetics. The mechanism of retinoprotective action may include sirtuin 1 (SIRT1) and matrix metalloproteinase 9 (MMP9) enzymes, as BGP-15 was able to elevate SIRT1 and decrease MMP9 expression in the eye. Based on our results, this emerging hydroximic acid derivative might be a future target of pharmacological developments as a potential drug against the harmful consequences of diabetes, such as diabetic retinopathy.

Mitochondrial Epigenetics: Non-Coding RNAs as a Novel Layer of Complexity

Mitochondria are organelles responsible for several functions involved in cellular balance, including energy generation and apoptosis. For decades now, it has been well-known that mitochondria have their own genetic material (mitochondrial DNA), which is different from nuclear DNA in many ways. More recently, studies indicated that, much like nuclear DNA, mitochondrial DNA is regulated by epigenetic factors, particularly DNA methylation and non-coding RNAs (ncRNAs). This field is now called mitoepigenetics. Additionally, it has also been established that nucleus and mitochondria are constantly communicating to each other to regulate different cellular pathways. However, little is known about the mechanisms underlying mitoepigenetics and nuclei-mitochondria communication, and also about the involvement of the ncRNAs in mitochondrial functions and related diseases. In this context, this review presents the state-of-the-art knowledge, focusing on ncRNAs as new players in mitoepigenetic regulation and discussing future perspectives of these fields.

Reclassifying Hepatic Cell Death during Liver Damage: Ferroptosis-A Novel Form of Non-Apoptotic Cell Death?

Ferroptosis has emerged as a new type of cell death in different pathological conditions, including neurological and kidney diseases and, especially, in different types of cancer. The hallmark of this regulated cell death is the presence of iron-driven lipid peroxidation; the activation of key genes related to this process such as glutathione peroxidase-4 (gpx4), acyl-CoA synthetase long-chain family member-4 (acsl4), carbonyl reductase [NADPH] 3 (cbr3), and prostaglandin peroxidase synthase-2 (ptgs2); and morphological changes including shrunken and electron-dense mitochondria. Iron overload in the liver has long been recognized as both a major trigger of liver damage in different diseases, and it is also associated with liver fibrosis. New evidence suggests that ferroptosis might be a novel type of non-apoptotic cell death in several liver diseases including non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALD), drug-induced liver injury (DILI), viral hepatitis, and hemochromatosis. The interaction between iron-related lipid peroxidation, cellular stress signals, and antioxidant systems plays a pivotal role in the development of this novel type of cell death. In addition, integrated responses from lipidic mediators together with free iron from iron-containing enzymes are essential to understanding this process. The presence of ferroptosis and the exact mechanisms leading to this non-apoptotic type of cell death in the liver remain scarcely elucidated. Recognizing ferroptosis as a novel type of cell death in the liver could lead to the understanding of the complex interaction between different types of cell death, their role in progression of liver fibrosis, the development of new biomarkers, as well as the use of modulators of ferroptosis, allowing improved theranostic approaches in the clinic.

Monolayerwise application of linear elasticity theory well describes strongly deformed lipid membranes and the effect of solvent

The theory of elasticity of lipid membranes is used widely to describe processes of cell membrane remodeling. Classically, the functional of a membrane's elastic energy is derived under assumption of small deformations; the membrane is considered as an infinitely thin film. This functional is quadratic on membrane surface curvature, with half of the splay modulus as its proportionality coefficient; it is generally applicable for small deformations only. Any validity of this functional for the regime of strong deformations should be verified experimentally. Recently, research using molecular dynamics simulations challenged the validity of this classic, linear model, i.e. the constancy of the splay modulus for strongly bent membranes. Here we demonstrate that the quadratic energy functional still can be applied for calculation of the elastic energy of strongly deformed membranes without introducing higher order terms with additional elastic moduli, but only if applied separately for each lipid monolayer. For cylindrical membranes, both classic and monolayerwise models yield equally accurate results. For cylindrical deformations we experimentally show that the elastic energy of lipid monolayers is additive: a low molecular weight solvent leads to an approximately twofold decrease in the membrane bending stiffness. Accumulation of solvent molecules in the inner monolayer of a membrane cylinder can explain these results, as the solvent partially prevents lipid molecules from splaying there. Thus, the linear theory of elasticity can be expanded through the range from weak to strong deformations-its simplicity and physical transparency describe various membrane phenomena.

Mechanisms of Human Immunodeficiency Virus-Associated Lymphocyte Regulated Cell Death

Human immunodeficiency virus-1 (HIV-1) causes CD4 T cell depletion through a number of mechanisms, including programmed cell death pathways (both apoptotic and nonapoptotic). In the setting of HIV-1 infection, the enhanced lymphocyte cell death occurs as a consequence of complex interactions between the host immune system and viral factors, which are reviewed herein. On the other hand, the main challenge to HIV-1 eradication is the development of latent infection in a subset of long lived cells, including CD4+ T cells and macrophages, which resist HIV-induced cell death. Understanding the potential mechanisms of how HIV-1 induces lymphocyte cell death is critical to the "kick and kill" cure strategy, which relies on the effective killing of reactivated, HIV-1-infected cells.

Acetylshikonin induces apoptosis of human leukemia cell line K562 by inducing S phase cell cycle arrest, modulating ROS accumulation, depleting Bcr-Abl and blocking NF-κB signaling

Acetylshikonin, a natural naphthoquinone derivative compound from Lithospermum erythrorhyzon, has been reported to kill bacteria, suppress inflammation, and inhibit tumor growth. However, the effect of acetylshikonin on human chronic myelocytic leukemia (CML) cells apoptosis and its detailed mechanisms remains unknown. The purpose of the present study was to investigate whether acetylshikonin could inhibit proliferation or induce apoptosis of the K562 cells, and whether by regulating the NF-κB signaling pathway to suppress the development of CML. K562 cells were treated with serial diluted acetylshikonin at different concentrations. Our data showed that K562 cell growth was significantly inhibited by acetylshikonin with an IC50 of 2.03 μM at 24 h and 1.13 μM at 48 h, with increased cell cycle arrest in S-phase. The results of annexin V-FITC/PI and AO/EB staining showed that acetylshikonin induced cell apoptosis in a dose-dependent manner. K562 cells treated with acetylshikonin underwent massive apoptosis accompanied by a rapid generation of reactive oxygen species (ROS). Scavenging the ROS completely blocked the induction of apoptosis following acetylshikonin treatment. The levels of the pro-apoptotic proteins Bax, cleaved caspase-9, cleaved PARP and cleaved caspase-3 increased with increased concentrations of acetylshikonin, while the level of the anti-apoptotic protein Bcl-2 was downregulated. The levels of Cyt C and AIF, which are characteristic proteins of the mitochondria-regulated intrinsic apoptotic pathway, also increased in the cytosol after acetylshikonin treatment. However, the mitochondrial fraction of Cyt C and AIF were decreased under acetylshikonin treatment. In addition, acetylshikonin decreased Bcr-Abl expression and inhibited its downstream signaling. Acetylshikonin could lead to a blockage of the NF-κB signaling pathway via decreasing nuclear NF-κB P65 and increasing cytoplasmic NF-κB P65. Moreover, acetylshikonin significantly inhibited the phosphorylation of IkBα and IKKα/β in K562 cells. These results demonstrated that acetylshikonin significantly inhibited K562 cell growth and induced cell apoptosis through the mitochondria-regulated intrinsic apoptotic pathway. The mechanisms may involve the modulating ROS accumulation, inhibition of NF-κB and BCR-ABL expression. The inhibition of BCR-ABL expression and the inactivation of the NF-κB signaling pathway caused by acetylshikonin treatment resulted in K562 cell apoptosis. Together, our results indicate that acetylshikonin could serve as a potential therapeutic agent for the future treatment of CML.

Characteristics of seasonal spermatogenesis in the soft-shelled turtle

Spermatogenesis in reptiles is a seasonally dependent physiological process that is not temporally associated with male mating behavior. Characteristics of seasonal spermatogenesis in reptiles, however, remain largely unknown. In this review, there is a coverage of the characteristics of soft-shelled turtle, Pelodiscus sinensis, during seasonal spermatogenesis that provides insights into spermatogenesis of testudines. The seminiferous epithelium of P. sinensis are undergoing spermatogenesis during the summer and fall, but are quiescent throughout the rest of the year; germ cells progress through spermatogenic stages in a temporal rather than a spatial pattern. While apoptotic germ cells mainly appear in the non-spermatogenic phase, these are seldom present during active spermatogenesis. It is inferred that apoptosis may be one of the reasons for germ cell loss during the resting phase of spermatogenesis. During the period when spermatogenesis is occurring, Sertoli cells become very narrow and are in contact with several round/elongated spermatids. Many residual spermatozoa can be internalized and degraded within Sertoli cells by entosis during the non-spermatogenic phase, which precedes the next reproductive cycle in P. sinensis. In the late spermatogenic phase, round-shaped mitochondria of spermatids become elongated and swollen, subsequently forming a crescent-like shape and develop into "onion-like" shaped mitochondria. As spermiogenesis progresses, the endoplasmic reticulum of spermatids is transferred into a specialized structure called the "Chrysanthemum flower center", which may be a source of autophagosomal membranes. The information provided in this review will help improve understanding of characteristics of seasonal spermatogenesis, which will hopefully promote interest in the study of reptilian species.

The carboxyl-terminal sequence of bim enables bax activation and killing of unprimed cells

The Bcl-2 family BH3 protein Bim promotes apoptosis at mitochondria by activating the pore-forming proteins Bax and Bak and by inhibiting the anti-apoptotic proteins Bcl-XL, Bcl-2 and Mcl-1. Bim binds to these proteins via its BH3 domain and to the mitochondrial membrane by a carboxyl-terminal sequence (CTS). In cells killed by Bim, the expression of a Bim mutant in which the CTS was deleted (BimL-dCTS) triggered apoptosis that correlated with inhibition of anti-apoptotic proteins being sufficient to permeabilize mitochondria isolated from the same cells. Detailed analysis of the molecular mechanism demonstrated that BimL-dCTS inhibited Bcl-XL but did not activate Bax. Examination of additional point mutants unexpectedly revealed that the CTS of Bim directly interacts with Bax, is required for physiological concentrations of Bim to activate Bax and that different residues in the CTS enable Bax activation and binding to membranes.

Potential Role of Tocotrienols on Non-Communicable Diseases: A Review of Current Evidence

Tocotrienol (T3) is a subfamily of vitamin E known for its wide array of medicinal properties. This review aimed to summarize the health benefits of T3, particularly in prevention or treatment of non-communicable diseases (NCDs), including cardiovascular, musculoskeletal, metabolic, gastric, and skin disorders, as well as cancers. Studies showed that T3 could prevent various NCDs, by suppressing 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) in the mevalonate pathway, inflammatory response, oxidative stress, and alternating hormones. The efficacy of T3 in preventing/treating these NCDs is similar or greater compared to tocopherol (TF). TF may lower the efficacy of T3 because the efficacy of the combination of TF and T3 was lower than T3 alone in some studies. Data investigating the effects of T3 on osteoporosis, arthritis, and peptic ulcers in human are limited. The positive outcomes of T3 treatment obtained from the preclinical studies warrant further validation from clinical trials.

Mitochondrial Quality Control: Role in Cardiac Models of Lethal Ischemia-Reperfusion Injury

The current standard of care for acute myocardial infarction or 'heart attack' is timely restoration of blood flow to the ischemic region of the heart. While reperfusion is essential for the salvage of ischemic myocardium, re-introduction of blood flow paradoxically kills (rather than rescues) a population of previously ischemic cardiomyocytes-a phenomenon referred to as 'lethal myocardial ischemia-reperfusion (IR) injury'. There is long-standing and exhaustive evidence that mitochondria are at the nexus of lethal IR injury. However, during the past decade, the paradigm of mitochondria as mediators of IR-induced cardiomyocyte death has been expanded to include the highly orchestrated process of mitochondrial quality control. Our aims in this review are to: (1) briefly summarize the current understanding of the pathogenesis of IR injury, and (2) incorporating landmark data from a broad spectrum of models (including immortalized cells, primary cardiomyocytes and intact hearts), provide a critical discussion of the emerging concept that mitochondrial dynamics and mitophagy (the components of mitochondrial quality control) may contribute to the pathogenesis of cardiomyocyte death in the setting of ischemia-reperfusion.

Carbon Nanotubes Enabling Highly Efficient Cell Apoptosis by Low-Intensity Nanosecond Electric Pulses via Perturbing Calcium Handling

Effective induction of targeted cancer cells apoptosis with minimum side effects has always been the primary objective for anti-tumor therapy. In this study, carbon nanotubes (CNTs) are employed for their unique ability to target tumors and amplify the localized electric field due to the high aspect ratio. Highly efficient and cancer cell specific apoptosis is finally achieved by combining carbon nanotubes with low intensity nanosecond electric pulses (nsEPs). The underlying mechanism may be as follows: the electric field produced by nsEPs is amplified by CNTs, causing an enhanced plasma membrane permeabilization and Ca²⁺ influx, simultaneously triggering Ca²⁺ release from intracellular storages to cytoplasm in a direct/indirect manner. All the changes above lead to excessive mitochondrial Ca²⁺ uptake. Substructural damage and obvious mitochondria membrane potential depolarization are caused subsequently with the combined action of numerously reactive oxygen species production, ultimately initiating the apoptotic process through the translocation of cytochrome c to the cytoplasm and activating apoptotic markers including caspase-9 and -3. Thus, the combination of nanosecond electric field with carbon nanotubes can actually promote HCT116 cell death via mitochondrial signaling pathway-mediated cell apoptosis. These results may provide a new and highly efficient strategy for cancer therapy.

Eriodictyol exerts potent anticancer activity against A549 human lung cancer cell line by inducing mitochondrial-mediated apoptosis, G2/M cell cycle arrest and inhibition of m-TOR/PI3K/Akt signalling pathway

INTRODUCTION

Eriodictyol is an important flavonoid and is commonly present across the plant kingdom. Flavonoids have been reported to show incredible pharmacological potential. However, the anticancer activity of the important flavonoid eriodictyol has not been well reported. In the present study we determined its anticancer potential against the human lung cancer cell line A549.

MATERIAL AND METHODS

The initial cytotoxicity induced by eriodictyol was measured by MTT assay. Flow cytometry was used to study the effects of eriodictyol on apoptosis, cell cycle phase distribution and mitochondrial membrane potential loss. The comet assay was used to measure DNA damage induced by eriodictyol in cancer cells while the western blot assay indicated effects of the compound on Bax/Blc-2 and PI3K/AKT/m-TOR proteins.

RESULTS

The results showed that eriodictyol has an IC₅₀ value of 50 μM against human lung cancer cells as compared to the IC₅₀ of 95 µM against non-cancerous FR2 cells. The molecule exerted its anticancer activity through induction of apoptosis by regulating the Bcl-2/Bax signalling pathway. It caused cell cycle arrest of human lung cancer A549 cells at G2/M phase. Eriodictyol was also found to cause a reduction of the mitochondrial membrane potential in a dose-dependent manner. Additionally, eriodictyol effectively inhibited the mTOR/PI3K/Akt signalling pathway in a dose-dependent manner.

CONCLUSIONS

Based on the above findings, we conclude that eriodictyol exerts its anticancer activity through induction of mitochondrial apoptosis and G2/M cell cycle arrest and inhibition of the TOR/PI3K/Akt cascade, indicating that it may have potential as a lead compound in the treatment of lung cancer, provided further in depth studies are done.

Recent advances in understanding the molecular genetic basis of mitochondrial disease

Mitochondrial disease is hugely diverse with respect to associated clinical presentations and underlying genetic causes, with pathogenic variants in over 300 disease genes currently described. Approximately half of these have been discovered in the last decade due to the increasingly widespread application of next generation sequencing technologies, in particular unbiased, whole exome-and latterly, whole genome sequencing. These technologies allow more genetic data to be collected from patients with mitochondrial disorders, continually improving the diagnostic success rate in a clinical setting. Despite these significant advances, some patients still remain without a definitive genetic diagnosis. Large datasets containing many variants of unknown significance have become a major challenge with next generation sequencing strategies and these require significant functional validation to confirm pathogenicity. This interface between diagnostics and research is critical in continuing to expand the list of known pathogenic variants and concomitantly enhance our knowledge of mitochondrial biology. The increasing use of whole exome sequencing, whole genome sequencing and other "omics" techniques such as transcriptomics and proteomics will generate even more data and allow further interrogation and validation of genetic causes, including those outside of coding regions. This will improve diagnostic yields still further and emphasizes the integral role that functional assessment of variant causality plays in this process-the overarching focus of this review.

Recent Progress in Mitochondria-Targeted Drug and Drug-Free Agents for Cancer Therapy

The mitochondrion is a dynamic eukaryotic organelle that controls lethal and vital functions of the cell. Being a critical center of metabolic activities and involved in many diseases, mitochondria have been attracting attention as a potential target for therapeutics, especially for cancer treatment. Structural and functional differences between healthy and cancerous mitochondria, such as membrane potential, respiratory rate, energy production pathway, and gene mutations, could be employed for the design of selective targeting systems for cancer mitochondria. A number of mitochondria-targeting compounds, including mitochondria-directed conventional drugs, mitochondrial proteins/metabolism-inhibiting agents, and mitochondria-targeted photosensitizers, have been discussed. Recently, certain drug-free approaches have been introduced as an alternative to induce selective cancer mitochondria dysfunction, such as intramitochondrial aggregation, self-assembly, and biomineralization. In this review, we discuss the recent progress in mitochondria-targeted cancer therapy from the conventional approach of drug/cytotoxic agent conjugates to advanced drug-free approaches.

The Role of the BCL-2 Family of Proteins in HIV-1 Pathogenesis and Persistence

Advances in HIV-1 therapy have transformed the once fatal infection into a manageable, chronic condition, yet the search for a widely applicable approach to cure remains elusive. The ineffectiveness of antiretroviral therapy (ART) in reducing the size of the HIV-1 latent reservoir has prompted investigation into the mechanisms of HIV-1 latency and immune escape. One of the major regulators of apoptosis, the BCL-2 protein, alongside its homologous family members, is a major target of HIV-1-induced change. Recent studies have now demonstrated the association of this protein with cells that support proviral forms in the setting of latency and have helped identify BCL-2 as a novel and promising therapeutic target for HIV-1 therapy directed at possible cure. This review aims to systematically review the interactions of HIV-1 with BCL-2 and its homologs and to examine the possibility of using BCL-2 inhibitors in the study and elimination of the latent reservoir.

Remodelling of mitochondria during spermiogenesis of Chinese soft-shelled turtle (Pelodiscus sinensis)

Mitochondria are vital cellular organelles that have the ability to change their shape under different conditions, such as in response to stress, disease, changes in metabolic rate, energy requirements and apoptosis. In the present study, we observed remodelling of mitochondria during spermiogenesis and its relationship with mitochondria-associated granules (MAG). At the beginning of spermiogenesis, mitochondria are characterised by their round shape. As spermiogenesis progresses, the round-shaped mitochondria change into elongated and then swollen mitochondria, subsequently forming a crescent-like shape and finally developing into onion-like shaped mitochondria. We also noted changes in mitochondrial size, location and patterns of cristae at different stages of spermiogenesis. Significant differences (P<0.0001) were found in the size of the different-shaped mitochondria. In early spermatids transitioning to the granular nucleus stage, the size of the mitochondria decreased, but increased subsequently during spermiogenesis. Changes in size and morphological variations were achieved through marked mitochondrial fusion. We also observed a non-membranous structure (MAG) closely associated with mitochondria that may stimulate or control fusion during mitochondrial remodelling. The end product of this sophisticated remodelling process in turtle spermatozoa is an onion-like mitochondrion. The acquisition of this kind of mitochondrial configuration is one strategy for long-term sperm storage in turtles.

Fenbendazole induces apoptosis of porcine uterine luminal epithelial and trophoblast cells during early pregnancy

Fenbendazole, is an effective benzimidazole anthelmintic that prevents parasite infection in both human and veterinary health care. Although the well-known and effect of benzimidazole was recently shown to have a broad spectrum of biological abilities, such as anticancer and anti-inflammation activities, the mechanism of benzimidazole's antiproliferative effect via cell signaling pathways and its role in preimplantation has not been studied. Therefore, the purpose of this study was to determine the effects of fenbendazole on porcine trophectoderm and luminal epithelial cells. First, we investigated cell viability in response to a low dose of fenbendazole, which highly inhibited cell proliferation. In addition, we investigated apoptotic molecules in the mitochondria, imbalanced intracellular calcium homeostasis, and the expression of some genes involved in apoptosis to explain the decrease in proliferation. Finally, we examined the intracellular mechanisms of fenbendazole by measuring the extracellular signal-regulated kinase, PI3K/AKT, and c-Jun N-terminal kinase signaling proteins by western blot analysis. Our findings suggest that fenbendazole functions as an effective anti-proliferative molecule that induces critical apoptosis in the porcine trophectoderm and uterine luminal epithelial cells by disrupting the mitochondria membrane potential during early pregnancy.

Efficient apoptosis requires feedback amplification of upstream apoptotic signals by effector caspase-3 or -7

Apoptosis is a complex multi-step process driven by caspase-dependent proteolytic cleavage cascades. Dysregulation of apoptosis promotes tumorigenesis and limits the efficacy of chemotherapy. To assess the complex interactions among caspases during apoptosis, we disrupted caspase-8, -9, -3, -7, or -6 and combinations thereof, using CRISPR-based genome editing in living human leukemia cells. While loss of apical initiator caspase-8 or -9 partially blocked extrinsic or intrinsic apoptosis, respectively, only combined loss of caspase-3 and -7 fully inhibited both apoptotic pathways, with no discernible effect of caspase-6 deficiency alone or in combination. Caspase-3/7 double knockout cells exhibited almost complete inhibition of caspase-8 or -9 activation. Furthermore, deletion of caspase-3 and -7 decreased mitochondrial depolarization and cytochrome c release upon apoptosis activation. Thus, activation of effector caspase-3 or -7 sets off explosive feedback amplification of upstream apoptotic events, which is a key feature of apoptotic signaling essential for efficient apoptotic cell death.