Mitochondrial cytochrome c release in apoptosis occurs upstream of DEVD-specific caspase activation and independently of mitochondrial transmembrane depolarization

Metallo-protease Peptidase M84 from Bacillusaltitudinis induces ROS-dependent apoptosis in ovarian cancer cells by targeting PAR-1

We have purified Peptidase M84 from Bacillus altitudinis in an effort to isolate anticancer proteases from environmental microbial isolates. This metallo-protease had no discernible impact on normal cell survival, but it specifically induced apoptosis in ovarian cancer cells. PAR-1, a GPCR which is reported to be overexpressed in ovarian cancer cells, was identified as a target of Peptidase M84. We observed that Peptidase M84 induced PAR-1 overexpression along with activating its downstream signaling effectors NF-κB and MAPK to promote excessive reactive oxygen species (ROS) generation. This evoked apoptotic death of the ovarian cancer cells through the intrinsic route. In in vivo set-up, weekly intraperitoneal administration of Peptidase M84 in syngeneic mice significantly diminished ascites accumulation, increasing murine survival rates by 60%. Collectively, our findings suggested that Peptidase M84 triggered PAR-1-mediated oxidative stress to act as an apoptosis inducer. This established Peptidase M84 as a drug candidate for receptor mediated targeted-therapy of ovarian cancer.

OMA1-Mediated Mitochondrial Dynamics Balance Organellar Homeostasis Upstream of Cellular Stress Responses

In response to cellular metabolic and signaling cues, the mitochondrial network employs distinct sets of membrane-shaping factors to dynamically modulate organellar structures through a balance of fission and fusion. While these organellar dynamics mediate mitochondrial structure/function homeostasis, they also directly impact critical cell-wide signaling pathways such as apoptosis, autophagy, and the integrated stress response (ISR). Mitochondrial fission is driven by the recruitment of the cytosolic dynamin-related protein-1 (DRP1), while fusion is carried out by mitofusins 1 and 2 (in the outer membrane) and optic atrophy-1 (OPA1) in the inner membrane. This dynamic balance is highly sensitive to cellular stress; when the transmembrane potential across the inner membrane (Δψm) is lost, fusion-active OPA1 is cleaved by the overlapping activity with m-AAA protease-1 (OMA1 metalloprotease, disrupting mitochondrial fusion and leaving dynamin-related protein-1 (DRP1)-mediated fission unopposed, thus causing the collapse of the mitochondrial network to a fragmented state. OMA1 is a unique regulator of stress-sensitive homeostatic mitochondrial balance, acting as a key upstream sensor capable of priming the cell for apoptosis, autophagy, or ISR signaling cascades. Recent evidence indicates that higher-order macromolecular associations within the mitochondrial inner membrane allow these specialized domains to mediate crucial organellar functionalities.

Shedding light on mitochondrial outer-membrane permeabilization and membrane potential: State of the art methods and biosensors

Membrane structural integrity is essential for optimal mitochondrial function. These organelles produce the energy needed for all vital processes, provided their outer and inner membranes are intact. This prevents the release of mitochondrial apoptogenic factors into the cytosol and ensures intact mitochondrial membrane potential (ΔΨm) to sustain ATP production. Cell death by apoptosis is generally triggered by outer mitochondrial membrane permeabilization (MOMP), tightly coupled with loss of ΔΨ m. As these two processes are essential for both mitochondrial function and cell death, researchers have devised various techniques to assess them. Here, we discuss current methods and biosensors available for detecting MOMP and measuring ΔΨ m, focusing on their advantages and limitations and discuss what new imaging tools are needed to improve our knowledge of mitochondrial function.

Dissection of MKK6 and p38 Signaling Using Light-Activated Protein Kinases

Stress-activated signaling pathways orchestrate cellular behaviors and fates. Studying the precise role(s) of stress-activated protein kinases is challenging, because stress conditions induce adaptation and impose selection pressure. To meet this challenge, we have applied an optogenetic system with a single plasmid to express light-activated p38α or its upstream activator, MKK6, in conjunction with live-cell fluorescence microscopy. In starved cells, decaging of constitutively active p38α or MKK6 by brief exposure to UV light elicits rapid p38-mediated signaling, release of cytochrome c from mitochondria, and apoptosis with different kinetics. In parallel, light activation of p38α also suppresses autophagosome formation, similarly to stimulation with growth factors that activate PI3K/Akt/mTORC1 signaling. Active MKK6 negatively regulates serum-induced ERK activity, which is p38-independent as previously reported. Here, we reproduce that result with the one plasmid system and show that although decaging active p38α does not reduce basal ERK activity in our cells, it can block growth factor-stimulated ERK signaling in serum-starved cells. These results clarify the roles of MKK6 and p38α in dynamic signaling programs, which act in concert to actuate apoptotic death while suppressing cell survival mechanisms.

Synthesis, molecular docking, and molecular dynamic simulation studies of new 1,3,4-thiadiazole derivatives as potential apoptosis inducers in A549 lung cancer cell line

1,3,4-Thiadiazoles are structures that are bioisosteres of 1,3,4-oxadiazole and pyrimidine ring, which are found in the structure of many drugs and anticancer active newly studied derivatives. In the past, high effect profiles have been observed in many molecules created, based on the anticancer effects of the 2-amino-1,3,4-thiadiazole (NSC 4728) molecule and acetazolamide molecules. Focusing on these molecules and evaluating them in terms of mechanistic effects, twelve new N-[5-((3,5-dichlorophenoxy) methyl]-1,3,4-thiadiazole derivatives (3a-3i) were synthesized and their biological activities were investigated in lung cancer cells. The anticancer effects of the compounds were evaluated on the A549 and L929 cell lines. Compound 3f, namely 2-[(5-chlorobenzotiyazol-2-yl)thio]-N-[5-[(3,5-dichlorophenoxy)methyl]-1,3,4-thiadiazol-2-yl]acetamide, showed better activity than cisplatin, exhibiting high inhibitory potency (IC50: <0.98 μg/mL) and selectivity against A549 cell line even at the lowest concentration tested. Compounds 3c, 3f, and 3h with the lowest IC50 values of the compounds exhibited an excellent percentage of apoptosis between 72.48 and 91.95% compared to cisplatin. The caspase-3 activation and mitochondrial membrane potential change of the aforementioned three compounds were also studied. Moreover, matrix metalloproteinase-9 (MMP-9) inhibition potential of all final compounds was also investigated and IC50 values for compounds 3b and 3g were identified as 154.23 and 107.28 µM. Molecular docking and molecular dynamic simulation studies for MMP-9 enzyme inhibition were realized on these compounds and the nitrogen atoms of amide and thiadiazole moieties' ascertained that they play a key role in chelating with Zn metal, at the same time, (thio)ether moieties allow conformational change resulting in the ligand can make more stable contacts.Communicated by Ramaswamy H. Sarma.

PGAM5 exacerbates acute renal injury by initiating mitochondria-dependent apoptosis by facilitating mitochondrial cytochrome c release

Acute kidney injury (AKI) is a worldwide public health problem characterized by the massive loss of tubular cells. However, the precise mechanism for initiating tubular cell death has not been fully elucidated. Here, we reported that phosphoglycerate mutase 5 (PGAM5) was upregulated in renal tubular epithelial cells during ischaemia/reperfusion or cisplatin-induced AKI in mice. PGAM5 knockout significantly alleviated the activation of the mitochondria-dependent apoptosis pathway and tubular apoptosis. Apoptosis inhibitors alleviated the activation of the mitochondria-dependent apoptosis pathway. Mechanistically, as a protein phosphatase, PGAM5 could dephosphorylate Bax and facilitate Bax translocation to the mitochondrial membrane. The translocation of Bax to mitochondria increased membrane permeability, decreased mitochondrial membrane potential and facilitated the release of mitochondrial cytochrome c (Cyt c) into the cytoplasm. Knockdown of Bax attenuated PGAM5 overexpression-induced Cyt c release and tubular cell apoptosis. Our results demonstrated that the increase in PGAM5-mediated Bax dephosphorylation and mitochondrial translocation was implicated in the development of AKI by initiating mitochondrial Cyt c release and activating the mitochondria-dependent apoptosis pathway. Targeting this axis might be beneficial for alleviating AKI.

Role of high-temperature requirement serine protease A 2 in rheumatoid inflammation

BACKGROUND

High-temperature requirement serine protease A 2 (HtrA2) is known to be involved in growth, unfolded protein response to stress, apoptosis, and autophagy. However, whether HtrA2 controls inflammation and immune response remains elusive.

METHODS

Expression of HtrA2 in the synovial tissue of patients was examined using immunohistochemistry and immunofluorescence staining. Enzyme-linked immunosorbent assay was used to determine the concentrations of HtrA2, interleukin-6 (IL-6), interleukin-8 (IL-8), chemokine (C-C motif) ligand 2 (CCL2), and tumor necrosis factor α (TNFα). Synoviocyte survival was assessed by MTT assay. For the downregulation of HtrA2 transcripts, cells were transfected with HtrA2 siRNA.

RESULTS

We found that the concentration of HtrA2 was elevated in rheumatoid arthritis (RA) synovial fluid (SF) than in osteoarthritis (OA) SF, and its concentrations were correlated with the number of immune cells in the RA SF. Interestingly, HtrA2 levels in the SF of RA patients were elevated in proportion to synovitis severity and correlated with the expression of proinflammation cytokines and chemokines, such as IL-6, IL-8, and CCL2. In addition, HtrA2 was highly expressed in RA synovium and primary synoviocytes. RA synoviocytes released HtrA2 when stimulated with ER stress inducers. Knockdown of HtrA2 inhibited the IL1β-, TNFα-, and LPS-induced release of proinflammatory cytokines and chemokines by RA synoviocytes.

CONCLUSION

HtrA2 is a novel inflammatory mediator and a potential target for the development of an anti-inflammation therapy for RA.

Mitochondria Have Made a Long Evolutionary Path from Ancient Bacteria Immigrants within Eukaryotic Cells to Essential Cellular Hosts and Key Players in Human Health and Disease

Mitochondria have made a long evolutionary path from ancient bacteria immigrants within the eukaryotic cell to become key players for the cell, assuming crucial multitasking skills critical for human health and disease. Traditionally identified as the powerhouses of eukaryotic cells due to their central role in energy metabolism, these chemiosmotic machines that synthesize ATP are known as the only maternally inherited organelles with their own genome, where mutations can cause diseases, opening up the field of mitochondrial medicine. More recently, the omics era has highlighted mitochondria as biosynthetic and signaling organelles influencing the behaviors of cells and organisms, making mitochondria the most studied organelles in the biomedical sciences. In this review, we will especially focus on certain 'novelties' in mitochondrial biology "left in the shadows" because, although they have been discovered for some time, they are still not taken with due consideration. We will focus on certain particularities of these organelles, for example, those relating to their metabolism and energy efficiency. In particular, some of their functions that reflect the type of cell in which they reside will be critically discussed, for example, the role of some carriers that are strictly functional to the typical metabolism of the cell or to the tissue specialization. Furthermore, some diseases in whose pathogenesis, surprisingly, mitochondria are involved will be mentioned.

Macrophage Resistance to Ionizing Radiation Exposure Is Accompanied by Decreased Cathepsin D and Increased Transferrin Receptor 1 Expression

PURPOSE

To identify a molecular signature of macrophages exposed to clinically relevant ionizing radiation (IR) doses, mirroring radiotherapy sessions.

METHODS

Human monocyte-derived macrophages were exposed to 2 Gy/ fraction/ day for 5 days, mimicking one week of cancer patient's radiotherapy. Protein expression profile by proteomics was performed.

RESULTS

A gene ontology analysis revealed that radiation-induced protein changes are associated with metabolic alterations, which were further supported by a reduction of both cellular ATP levels and glucose uptake. Most of the radiation-induced deregulated targets exhibited a decreased expression, as was the case of cathepsin D, a lysosomal protease associated with cell death, which was validated by Western blot. We also found that irradiated macrophages exhibited an increased expression of the transferrin receptor 1 (TfR1), which is responsible for the uptake of transferrin-bound iron. TfR1 upregulation was also found in tumor-associated mouse macrophages upon tumor irradiation. In vitro irradiated macrophages also presented a trend for increased divalent metal transporter 1 (DMT1), which transports iron from the endosome to the cytosol, and a significant increase in iron release.

CONCLUSIONS

Irradiated macrophages present lower ATP levels and glucose uptake, and exhibit decreased cathepsin D expression, while increasing TfR1 expression and altering iron metabolism.

Phenolic-rich feijoa extracts from flesh, peel and whole fruit activate apoptosis pathways in the LNCaP cell line

This study aimed to explore the potential anticancer activity of phenolic-rich feijoa extracts from the flesh, peel, and whole fruit on the human prostate cancer cell line (LNCaP). Results showed that feijoa extracts had cancer-specific anti-proliferative activity on the LNCaP cell line. The anticancer activity of feijoa extracts was shown through activation of the caspase-dependent apoptosis pathway based on the increase of sub-G1 phase in the cell cycle, the decrease of mitochondrial membrane potential, as well as the elevated caspase 3, 8, and 9 activity in the treated LNCaP cells. The anti-cancer activity of feijoa extracts could be attributed to the high total phenolic contents (0.14-0.37 mg GAE/mg dw) and, in particular, the high ellagic acid content (2.662-9.119 μg/mg dw). The successful activation of the caspase-dependent apoptosis pathway indicates that phenolic-rich feijoa extracts have a good potential to be utilized as a functional ingredient in foods and nutraceuticals.

Ca2+-mediated mitochondrial inner membrane permeabilization induces cell death independently of Bax and Bak

The ability of mitochondria to buffer a rapid rise in cytosolic Ca²⁺ is a hallmark of proper cell homeostasis. Here, we employed m-3M3FBS, a putative phospholipase C (PLC) agonist, to explore the relationships between intracellular Ca²⁺ imbalance, mitochondrial physiology, and cell death. m-3M3FBS induced a potent dose-dependent Ca²⁺ release from the endoplasmic reticulum (ER), followed by a rise in intra-mitochondrial Ca²⁺. When the latter exceeded the organelle buffering capacity, an abrupt mitochondrial inner membrane permeabilization (MIMP) occurred, releasing matrix contents into the cytosol. MIMP was followed by cell death that was independent of Bcl-2 family members and inhibitable by the intracellular Ca²⁺ chelator BAPTA-AM. Cyclosporin A (CsA), capable of blocking the mitochondrial permeability transition (MPT), completely prevented cell death induced by m-3M3FBS. However, CsA acted upstream of mitochondria by preventing Ca²⁺ release from ER stores. Therefore, loss of Ca²⁺ intracellular balance and mitochondrial Ca²⁺ overload followed by MIMP induced a cell death process that is distinct from Bcl-2 family-regulated mitochondrial outer membrane permeabilization (MOMP). Further, the inhibition of cell death by CsA or its analogues can be independent of effects on the MPT.

Structure-activity relationships reveal a 2-furoyloxychalcone as a potent cytotoxic and apoptosis inducer for human U-937 and HL-60 leukaemia cells

Synthetic flavonoids with new substitution patterns have attracted attention as potential anticancer drugs. Here, twelve chalcones were synthesized and their antiproliferative activities against five human tumour cells were evaluated. This series of chalcone derivatives was characterized by the presence of an additional aromatic or heterocyclic ring linked by an ether, in the case of a benzyl radical, or an ester or amide functional group in the case of a furoyl radical. In addition, the influence on cytotoxicity by the presence of one or three methoxy groups or a 2,4-dimethoxy-3-methyl system on the B ring of the chalcone scaffold was also explored. The results revealed that the most cytotoxic chalcones contain a furoyl substituent linked by an ester or an amide through the 2'-hydroxy or the 2'-amino group of the A ring of the chalcone skeleton, with IC₅₀ values between 0.2 ± 0.1 μM and 1.3 ± 0.1 μM against human leukaemia cells. The synthetic chalcone 2'-furoyloxy-4-methoxychalcone (FMC) was, at least, ten-fold more potent than the antineoplastic agent etoposide against U-937 cells and displayed less cytotoxicity against human peripheral blood mononuclear cells. Treatment of U-937 and HL-60 cells with FMC induced cell cycle arrest at the G₂-M phase, an increase in the percentage of sub-G₁ and annexin-V positive cells, the release of mitochondrial cytochrome c, activation of caspase and poly(ADP-ribose) polymerase cleavage. In addition, it inhibited tubulin polymerization in vitro in a concentration dependent manner. Cell death triggered by this chalcone was decreased by the pan-caspase inhibitor z-VAD-fmk and was dependent of the generation of reactive oxygen species. We conclude that this furoyloxychalcone may be useful in the development of a potential anti-leukaemia strategy.

Effect of E-64 Supplementation during In Vitro Maturation on the Developmental Competence of Bovine OPU-Derived Oocytes

Recovery of bovine oocytes using the ovum pick-up (OPU) technique offers the advantage of rapid genetic improvement through propagation of desired genes from animals with high genetic qualities. However, the developmental competence of OPU-derived immature oocytes remains relatively poor. We previously found that cathepsin B gene expression and activity are increased in poor quality oocytes and embryos compared to good quality ones. In this study, we investigated the effect of E-64 (cathepsin B inhibitor) supplementation during in vitro maturation (IVM) on the developmental competence of OPU-derived immature oocytes and the quality of the produced blastocysts. Our results showed that supplementation of IVM medium with E-64 significantly improved the developmental competence of OPU-derived immature oocytes as evidenced by the significant increase of the blastocyst rate. Importantly, the presence of E-64 during IVM also significantly improved blastocyst quality by increasing the total cell number and decreasing the percentage of TUNEL positive cells. These results indicate that E-64 supplementation during IVM is a promising tool to improve the efficiency of OPU-IVF program by improving the developmental competence of OPU-derived immature oocytes.

A Bivalent Activatable Fluorescent Probe for Screening and Intravital Imaging of Chemotherapy-Induced Cancer Cell Death

The detection and quantification of apoptotic cells is a key process in cancer research, particularly during the screening of anticancer therapeutics and in mechanistic studies using preclinical models. Intravital optical imaging enables high-resolution visualisation of cellular events in live organisms; however, there are few fluorescent probes that can reliably provide functional readouts in situ without interference from tissue autofluorescence. We report the design and optimisation of the fluorogenic probe Apotracker Red for real-time detection of cancer cell death. The strong fluorogenic behaviour, high selectivity, and excellent stability of Apotracker Red make it a reliable optical reporter for the characterisation of the effects of anticancer drugs in cells in vitro and for direct imaging of chemotherapy-induced apoptosis in vivo in mouse models of breast cancer.

Sulphenylation of CypD at Cysteine 104: A Novel Mechanism by Which SO2 Inhibits Cardiomyocyte Apoptosis

Objectives: The study was designed to explore the role of endogenous gaseous signaling molecule sulfur dioxide (SO2) in the control of cardiomyocyte apoptosis and its molecular mechanisms.

Methods: Neonatal mouse cardiac myocytes (NMCMs) and H9c2 cells were used in the cell experiments. The endogenous SO2 pathway including SO2 level and the expression of SO2-generating enzyme aspartate aminotransferase 1/2 (AAT1/2) were detected in NMCMs. The apoptosis of cardiomyocytes was examined by a TUNEL assay. The cleavage and the activity of apoptotic proteins caspase9 and caspase3 were measured. The content of ATP, the opening of mitochondrial permeability transition pore (mPTP), and the cytochrome c (cytc) leakage were detected by immunofluorescence. The sulphenylation of cyclophilin-D (CypD) was detected by biotin switch analysis. The four CypD mutant plasmids in which cysteine sites were mutated to serine were constructed to identify the SO2-affected site in vitro.

Results: ISO down-regulated the endogenous SO2/AAT pathway of cardiomyocytes in association with a significant increase in cardiomyocyte apoptosis, demonstrated by the increases in apoptosis, cleaved-caspase3/caspase3 ratio, and caspase3 activity. Furthermore, ISO significantly reduced ATP production in H9c2 cells, but the supplement of SO2 significantly restored the content of ATP. ISO stimulated mPTP opening, resulting in an increase in the release of cytc, which further increased the ratio of cleaved caspase9/caspase9 and enhanced the protein activity of caspase9. While, the supplementation of SO2 reversed the above effects. Mechanistically, SO2 did not affect CypD protein expression, but sulphenylated CypD and inhibited mPTP opening, resulting in an inhibition of cardiomyocyte apoptosis. The C104S mutation in CypD abolished SO2-induced sulphenylation of CypD, and thereby blocked the inhibitory effect of SO2 on the mPTP opening and cardiomyocyte apoptosis.

Conclusion: Endogenous SO2 sulphenylated CypD at Cys104 to inhibit mPTP opening, and thus protected against cardiomyocyte apoptosis.

Citrinin impairs pig oocyte maturation by inducing oxidative stress and apoptosis

Citrinin (CTN) is a polyketide mycotoxin produced by several strains of Penicillium, Monascus, and Aspergillus. While CTN poses various toxic effects on the female reproductive system in animals, its direct effects on germ cell development are unclear. This study aimed to evaluate the effects of increasing concentrations of CTN (0,20,40,80,100 μM) on porcine oocyte in vitro maturation. Our results indicate that CTN supplementation inhibited polar body extrusion in a dose-dependent manner. Actin and spindle assembly were also disrupted after treatment, indicating that CTN affects the cytoskeleton of porcine oocytes. Oxidative stress and apoptosis were observed under CTN treatment to explore the cause of meiotic maturation failure in porcine oocytes. The results showed that reactive oxygen species levels, cathepsin B activity, and caspase-3 activity were increased in the treated group, indicating that CTN induced oxidative stress and apoptosis. In conclusion, CTN exposure could reduce porcine oocyte maturation by affecting cytoskeletal dynamics, oxidative stress, and apoptosis.

Folic acid Ameliorates the Declining Quality of Sodium Fluoride-Exposed Mouse Oocytes through the Sirt1/Sod2 Pathway

Excessive sodium fluoride (NaF) intake interferes with reproductive function in humans and animals; however, strategies to prevent these effects are still underexplored. Here, we showed that in vivo and in vitro supplementation of folic acid (FA) efficaciously improved the quality of NaF-exposed oocytes. FA supplementation not only increased ovulation of oocytes from NaF-treated mice but also enhanced oocyte meiotic competency and fertilization ability by restoring the spindle/chromosome structure. Moreover, FA supplementation could exert a beneficial effect on NaF- exposed oocytes by restoring mitochondrial function, eliminating reactive oxygen species accumulation to suppress apoptosis. We also found that FA supplementation restored the defective phenotypes in oocytes through a Sirt1/Sod2-dependent mechanism. Inhibition of Sirt1 with EX527 abolished the FA-mediated improvement in NaF-exposed oocyte quality. Collectively, our data indicated that FA supplementation is a feasible approach to protect oocytes from NaF-related deterioration.

The Yin and Yang of ERBB4: Tumor Suppressor and Oncoprotein

ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, a family that includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are oncoproteins and validated targets for therapeutic intervention in a variety of solid tumors. In contrast, the role that ERBB4 plays in human malignancies is ambiguous. Thus, here we review the literature regarding ERBB4 function in human malignancies. We review the mechanisms of ERBB4 signaling with an emphasis on mechanisms of signaling specificity. In the context of this signaling specificity, we discuss the hypothesis that ERBB4 appears to function as a tumor suppressor protein and as an oncoprotein. Next, we review the literature that describes the role of ERBB4 in tumors of the bladder, liver, prostate, brain, colon, stomach, lung, bone, ovary, thyroid, hematopoietic tissues, pancreas, breast, skin, head, and neck. Whenever possible, we discuss the possibility that ERBB4 mutants function as biomarkers in these tumors. Finally, we discuss the potential roles of ERBB4 mutants in the staging of human tumors and how ERBB4 function may dictate the treatment of human tumors. SIGNIFICANCE STATEMENT: This articles reviews ERBB4 function in the context of the mechanistic model that ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR or ERBB4-ERBB2 heterodimers act as oncogenes. Thus, this review serves as a mechanistic framework for clinicians and scientists to consider the role of ERBB4 and ERBB4 mutants in staging and treating human tumors.

Optical/electrochemical methods for detecting mitochondrial energy metabolism

This review highlights the biological importance of mitochondrial energy metabolism and the applications of multiple optical/electrochemical approaches to determine energy metabolites. Mitochondria, the main sites of oxidative phosphorylation and adenosine triphosphate (ATP) biosynthesis, provide the majority of energy required by aerobic cells for maintaining their physiological activity. They also participate in cell growth, differentiation, information transmission, and apoptosis. Multiple mitochondrial diseases, caused by internal or external factors, including oxidative stress, intense fluctuations of the ionic concentration, abnormal oxidative phosphorylation, changes in electron transport chain complex enzymes and mutations in mitochondrial DNA, can occur during mitochondrial energy metabolism. Therefore, developing accurate, sensitive, and specific methods for the in vivo and in vitro detection of mitochondrial energy metabolites is of great importance. In this review, we summarise the mitochondrial structure, functions, and crucial energy metabolic signalling pathways. The mechanism and applications of different optical/electrochemical methods are thoroughly reviewed. Finally, future research directions and challenges are proposed.

A Bivalent Activatable Fluorescent Probe for Screening and Intravital Imaging of Chemotherapy-induced Cancer Cell Death

The detection and quantification of apoptotic cells is a key process in cancer research, particularly during the screening of anticancer therapeutics and in mechanistic studies using preclinical models. Intravital optical imaging enables high‐resolution visualisation of cellular events in live organisms; however, there are few fluorescent probes that can reliably provide functional readouts in situ without interference from tissue autofluorescence. We report the design and optimisation of the fluorogenic probe Apotracker Red for real‐time detection of cancer cell death. The strong fluorogenic behaviour, high selectivity, and excellent stability of Apotracker Red make it a reliable optical reporter for the characterisation of the effects of anticancer drugs in cells in vitro and for direct imaging of chemotherapy‐induced apoptosis in vivo in mouse models of breast cancer.

Cathepsin B Regulates Mice Granulosa Cells' Apoptosis and Proliferation In Vitro

Cathepsin B (CTSB), a lysosomal cysteine protease’s high expression and activity, has been reported to cause poor-quality embryos in porcine and bovine. Nevertheless, CTSB functions in mice granulosa cells remain to explore. To discuss the CTSB functional role in follicular dynamics, we studied apoptosis, proliferation, cell cycle progression, and related signaling pathways in primary mouse granulosa cells transfected with small interference RNA specific to CTSB (siCTSB) for 48 h. Further, mRNA and protein expression of cell proliferation regulators (Myc and cyclin D2), apoptosis regulators (caspase 3, caspase 8, TNF-α, and Bcl2), steroidogenesis-related genes (FSHR and CYP11A1), and autophagy markers (LC3-I and ATG5) were investigated. In addition, the effect of CTSB on steroidogenesis and autophagy was also examined. Flow cytometry analysis assay displayed that silencing of CTSB decreased the early and total apoptosis rate by downregulating TNF-α, caspase 8, and caspase 3, and upregulating Bcl2. By regulating Myc and cyclin D2 expression and activating the p-Akt and p-ERK pathways, CTSB knockdown increased GC proliferation and number. A significant decline in estradiol and progesterone concentrations was observed parallel to a significant decrease in autophagy-related markers LC3-I and ATG5 compared to the control group. Herein, we demonstrated that CTSB serves as a proapoptotic agent and plays a critical role in folliculogenesis in female mice by mediating apoptosis, autophagy, proliferation, and steroidogenesis. Hence, CTSB could be a potential prognostic agent for female infertility.

Vitrification-induced activation of lysosomal cathepsin B perturbs spindle assembly checkpoint function in mouse oocytes

As the age of child-bearing increases and correlates with infertility, cryopreservation of female gametes is becoming common-place in ART. However, the developmental competence of vitrified oocytes has remained low. The underlying mechanisms responsible for reduced oocyte quality post-vitrification are largely unknown. Mouse cumulus-oocyte complexes were vitrified using a cryoloop technique and a mixture of dimethylsulphoxide, ethylene glycol and trehalose as cryoprotectants. Fresh and vitrified/thawed oocytes were compared for chromosome alignment, spindle morphology, kinetochore-microtubule attachments, spindle assembly checkpoint (SAC) and aneuploidy. Although the majority of vitrified oocytes extruded the first polar body (PB), they had a significant increase of chromosome misalignment, abnormal spindle formation and aneuploidy at metaphase II. In contrast to controls, vitrified oocytes extruded the first PB in the presence of nocodazole and etoposide, which should induce metaphase I arrest in a SAC-dependent manner. The fluorescence intensity of mitotic arrest deficient 2 (MAD2), an essential SAC protein, at kinetochores was reduced in vitrified oocytes, indicating that the SAC is weakened after vitrification/thawing. Furthermore, we found that vitrification-associated stress disrupted lysosomal function and stimulated cathepsin B activity, with a subsequent activation of caspase 3. MAD2 localization and SAC function in vitrified oocytes were restored upon treatment with a cathepsin B or a caspase 3 inhibitor. This study was conducted using mouse oocytes, therefore confirming these results in human oocytes is a prerequisite before applying these findings in IVF clinics. Here, we uncovered underlying molecular pathways that contribute to an understanding of how vitrification compromises oocyte quality. Regulating these pathways will be a step toward improving oocyte quality post vitrification and potentially increasing the efficiency of the vitrification program.

Photocontrolled apoptosis induction using precursor miR-664a and an RNA carrier-conjugated with photosensitizer

Methods to spatially induce apoptosis are useful for cancer therapy. To control the induction of apoptosis, methods using light, such as photochemical internalization (PCI), have been developed. We hypothesized that photoinduced delivery of microRNAs (miRNAs) that regulate apoptosis could spatially induce apoptosis. In this study, we identified pre-miR-664a as a novel apoptosis-inducing miRNA via mitochondrial apoptotic pathway. Further, we demonstrated the utility of photoinduced cytosolic dispersion of RNA (PCDR), which is an intracellular RNA delivery method based on PCI. Indeed, apoptosis is spatially regulated by pre-miR-664a and PCDR. In addition, we found that apoptosis induced by pre-miR-664a delivered by PCDR was more rapid than that by lipofection. These results suggest that pre-miR-664a is a nucleic acid drug candidate for cancer therapy and PCDR and pre-miR-664a-based strategies have potential therapeutic uses for diseases affecting various cell types.

Dynamin-related protein 1 deficiency accelerates lipopolysaccharide-induced acute liver injury and inflammation in mice

Mitochondrial fusion and fission, which are strongly related to normal mitochondrial function, are referred to as mitochondrial dynamics. Mitochondrial fusion defects in the liver cause a non-alcoholic steatohepatitis-like phenotype and liver cancer. However, whether mitochondrial fission defect directly impair liver function and stimulate liver disease progression, too, is unclear. Dynamin-related protein 1 (DRP1) is a key factor controlling mitochondrial fission. We hypothesized that DRP1 defects are a causal factor directly involved in liver disease development and stimulate liver disease progression. Drp1 defects directly promoted endoplasmic reticulum (ER) stress, hepatocyte death, and subsequently induced infiltration of inflammatory macrophages. Drp1 deletion increased the expression of numerous genes involved in the immune response and DNA damage in Drp1LiKO mouse primary hepatocytes. We administered lipopolysaccharide (LPS) to liver-specific Drp1-knockout (Drp1LiKO) mice and observed an increased inflammatory cytokine expression in the liver and serum caused by exaggerated ER stress and enhanced inflammasome activation. This study indicates that Drp1 defect-induced mitochondrial dynamics dysfunction directly regulates the fate and function of hepatocytes and enhances LPS-induced acute liver injury in vivo.

Cytotoxicity and Apoptosis Induced by Chenopodium ambrosioides L. Essential Oil in Human Normal Liver Cell Line L02 via the Endogenous Mitochondrial Pathway Rather Than the Endoplasmic Reticulum Stress

Chenopodium ambrosioides L. (C. ambrosioides) has been used as dietary condiments and as traditional medicine in South America. The oil of Chenopodium ambrosioides L. (C. ambrosioides) can be used as a natural antioxidant in food processing. It also has analgesic, sedating, and deworming effects, and can be used along with the whole plant for its medical effects: decongestion, as an insecticide, and to offer menstruation pain relief. This study was conducted to investigate the cytotoxicity and apoptosis effects of an essential oil from C. ambrosioides in vitro. The cytotoxicity evaluation of the essential oil from C. ambrosioides on human normal liver cell line L02 was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. AO/EB dual fluorescent staining assay and Annexin V-FITC were used for apoptosis analysis. The changes in mitochondrial membrane potential (MMP) were analyzed with 5,5,6,6′-tetrachloro-1,1,3,3,-tetraethyl-imidacarbocyanine iodide (JC-1) dye under a fluorescence microscope. The level of apoptosis related protein expression was quantified by Western blot. The L02 cells were treated with the essential oil from C. ambrosioides at 24, 48, and 72 h, and the IC₅₀ values were 65.45, 58.03, and 35.47 μg/mL, respectively. The AO/EB staining showed that viable apoptotic cells, non-viable apoptotic cells, and non-viable non-apoptotic cells appeared among the L02 cells under the fluorescence microscope. Cell cycle arrest at the S phase and cell apoptosis increased through flow cytometry in the L02 cells treated with the essential oil. MMP decreased in a concentration-dependent manner, as seen through JC-1 staining under the fluorescence microscope. In the L02 cells as shown by Western blot and qPCR, the amount of the apoptosis-related proteins and the mRNA expression levels of cytochrome C, Bax, Caspase-9, and Caspase-3 increased, Bcl-2 decreased, and Caspase-12, which is expressed in the endoplasmic reticulum, showed no obvious changes in protein amount or mRNA expression level. The essential oil form C. ambrosioides had a cytotoxic effect on L02 cells. It could inhibit L02 cell proliferation, arrest the cell cycle at the S phase, and induce L02 cell apoptosis through the endogenous mitochondrial pathway.

Understanding Post Entry Sorting of Adenovirus Capsids; A Chance to Change Vaccine Vector Properties

Adenovirus vector-based genetic vaccines have emerged as a powerful strategy against the SARS-CoV-2 health crisis. This success is not unexpected because adenoviruses combine many desirable features of a genetic vaccine. They are highly immunogenic and have a low and well characterized pathogenic profile paired with technological approachability. Ongoing efforts to improve adenovirus-vaccine vectors include the use of rare serotypes and non-human adenoviruses. In this review, we focus on the viral capsid and how the choice of genotypes influences the uptake and subsequent subcellular sorting. We describe how understanding capsid properties, such as stability during the entry process, can change the fate of the entering particles and how this translates into differences in immunity outcomes. We discuss in detail how mutating the membrane lytic capsid protein VI affects species C viruses' post-entry sorting and briefly discuss if such approaches could have a wider implication in vaccine and/or vector development.

The inhibition of microtubule dynamics instability alters lipid homeostasis in TM4 Sertoli cells

Sertoli cells (SC) structurally support and transport nutrients to germ cells during spermatogenesis facilitated by an active cytoskeleton. Chemical perturbation of SC microtubule (MT) dynamics instability leads to premature germ cell exfoliation demonstrating that this process is essential for male fertility, yet the effects of MT damaging drugs on SC lipid metabolism have been less explored. The aim of this study was to advance our understanding of how adequate SC MT dynamicity is needed to finely tune lipid homeostasis. To elucidate the role of MT dynamics instability on the latter, we suppressed MT dynamicity by long-term exposures to 10 nM of nocodazole (NCZ) on TM4-SC cultures. Inhibition of MT dynamics instability affected the distribution of [³H] arachidonate on TM4-SC. Triacylglycerols (TAG) exhibited a higher proportion of the [³H] label, with significantly lower percentages in the mitochondrial phospholipid cardiolipin, and notably, also in phosphatidylethanolamine. A noteworthy and progressive accumulation of lipid droplets during the period of exposure to NCZ was accompanied by increased TAG levels but not cholesterol levels in TM4-SC. NCZ-exposed cells reduced their mitochondrial membrane potential and increased ROS production without triggering apoptosis, had a compromised autophagic flux, and lost their transferrin expression. Although SC morphology was preserved, the NCZ-exposed cells displayed alteration of the normal organization of microfilaments (f-actin) and intermediate filaments (vimentin). Our findings suggest that a preserved MT dynamicity is essential in the maintenance of lipid and fatty acids homeostasis in SC, and thus highlights a novel target in these cells for drugs that impair MT dynamicity.

Opa1 Deficiency Promotes Development of Retinal Vascular Lesions in Diabetic Retinopathy

This study investigates whether reduced optic atrophy 1 (Opa1) level promotes apoptosis and retinal vascular lesions associated with diabetic retinopathy (DR). Four groups of mice: wild type (WT) control mice, streptozotocin (STZ)-induced diabetic mice, Opa1^+/- mice, and diabetic Opa1^+/- mice were used in this study. 16 weeks after diabetes onset, retinas were assessed for Opa1 and Bax levels by Western blot analysis, and retinal networks were examined for acellular capillaries (AC) and pericyte loss (PL). Apoptotic cells were detected in retinal capillaries using TUNEL assay, and caspase-3 activity was assessed using fluorometric analysis. Opa1 expression was significantly downregulated in retinas of diabetic and Opa1^+/- mice compared with those of WT mice. Inducing diabetes further decreased Opa1 expression in retinas of Opa1^+/- mice. Increased cytochrome c release concomitant with increased level of pro-apoptotic Bax and elevated caspase-3 activity were observed in retinas of diabetic and Opa1^+/- mice; the number of TUNEL-positive cells and AC/PL was also significantly increased. An additional decrease in the Opa1 level in retinas of diabetic Opa1^+/- mice exacerbated the development of apoptotic cells and AC/PL compared with those of diabetic mice. Diabetes-induced Opa1 downregulation contributes, at least in part, to the development of retinal vascular lesions characteristic of DR.

Ethanol Enhances Hyperthermia-Induced Cell Death in Human Leukemia Cells

Ethanol has been shown to exhibit therapeutic properties as an ablative agent alone and in combination with thermal ablation. Ethanol may also increase sensitivity of cancer cells to certain physical and chemical antitumoral agents. The aim of our study was to assess the potential influence of nontoxic concentrations of ethanol on hyperthermia therapy, an antitumoral modality that is continuously growing and that can be combined with classical chemotherapy and radiotherapy to improve their efficiency. Human leukemia cells were included as a model in the study. The results indicated that ethanol augments the cytotoxicity of hyperthermia against U937 and HL60 cells. The therapeutic benefit of the hyperthermia/ethanol combination was associated with an increase in the percentage of apoptotic cells and activation of caspases-3, -8 and -9. Apoptosis triggered either by hyperthermia or hyperthermia/ethanol was almost completely abolished by a caspase-8 specific inhibitor, indicating that this caspase plays a main role in both conditions. The role of caspase-9 in hyperthermia treated cells acquired significance whether ethanol was present during hyperthermia since the alcohol enhanced Bid cleavage, translocation of Bax from cytosol to mitochondria, release of mitochondrial apoptogenic factors, and decreased of the levels of the anti-apoptotic factor myeloid cell leukemia-1 (Mcl-1). The enhancement effect of ethanol on hyperthermia-activated cell death was associated with a reduction in the expression of HSP70, a protein known to interfere in the activation of apoptosis at different stages. Collectively, our findings suggest that ethanol could be useful as an adjuvant in hyperthermia therapy for cancer.

Canine Parvovirus and Its Non-Structural Gene 1 as Oncolytic Agents: Mechanism of Action and Induction of Anti-Tumor Immune Response

The exploration into the strategies for the prevention and treatment of cancer is far from complete. Apart from humans, cancer has gained considerable importance in animals because of increased awareness towards animal health and welfare. Current cancer treatment regimens are less specific towards tumor cells and end up harming normal healthy cells. Thus, a highly specific therapeutic strategy with minimal side effects is the need of the hour. Oncolytic viral gene therapy is one such specific approach to target cancer cells without affecting the normal cells of the body. Canine parvovirus (CPV) is an oncolytic virus that specifically targets and kills cancer cells by causing DNA damage, caspase activation, and mitochondrial damage. Non-structural gene 1 (NS1) of CPV, involved in viral DNA replication is a key mediator of cytotoxicity of CPV and can selectively cause tumor cell lysis. In this review, we discuss the oncolytic properties of Canine Parvovirus (CPV or CPV2), the structure of the NS1 protein, the mechanism of oncolytic action as well as role in inducing an antitumor immune response in different tumor models.

Mitochondrial OMA1 and OPA1 as Gatekeepers of Organellar Structure/Function and Cellular Stress Response

Mammalian mitochondria are emerging as a critical stress-responsive contributor to cellular life/death and developmental outcomes. Maintained as an organellar network distributed throughout the cell, mitochondria respond to cellular stimuli and stresses through highly sensitive structural dynamics, particularly in energetically demanding cell settings such as cardiac and muscle tissues. Fusion allows individual mitochondria to form an interconnected reticular network, while fission divides the network into a collection of vesicular organelles. Crucially, optic atrophy-1 (OPA1) directly links mitochondrial structure and bioenergetic function: when the transmembrane potential across the inner membrane (ΔΨ_m) is intact, long L-OPA1 isoforms carry out fusion of the mitochondrial inner membrane. When ΔΨ_m is lost, L-OPA1 is cleaved to short, fusion-inactive S-OPA1 isoforms by the stress-sensitive OMA1 metalloprotease, causing the mitochondrial network to collapse to a fragmented population of organelles. This proteolytic mechanism provides sensitive regulation of organellar structure/function but also engages directly with apoptotic factors as a major mechanism of mitochondrial participation in cellular stress response. Furthermore, emerging evidence suggests that this proteolytic mechanism may have critical importance for cell developmental programs, particularly in cardiac, neuronal, and stem cell settings. OMA1’s role as a key mitochondrial stress-sensitive protease motivates exciting new questions regarding its mechanistic regulation and interactions, as well as its broader importance through involvement in apoptotic, stress response, and developmental pathways.

Analysis of Mitochondrial Dysfunction During Cell Death

Mitochondria play a key role in various modes of cell death. Analysis of mitochondrial dysfunction and the release of proteins from the intermembrane space of mitochondria represent essential tools in cell death investigation. Here we describe how to evaluate release of intermembrane space proteins during apoptosis, alterations in the mitochondrial membrane potential, and oxygen consumption in apoptotic cells.

A Mechanistic Investigation on the Anticancer Properties of SYA013, a Homopiperazine Analogue of Haloperidol with Activity against Triple Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is one of the most malignant cancers associated with early metastasis, poor clinical prognosis, and high recurrence rate. TNBC is a distinct subtype of breast cancer that lacks estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 receptors (HER2). Development of effective TNBC therapies has been limited partially due to the lack of specific molecular targets and chemotherapy involving different cytotoxic drugs suffers from significant side effects and drug-resistance development. Therefore, there is an unmet need for the development of novel and efficient therapeutic drugs with reduced side effects to treat TNBC. We have previously reported that certain analogues of haloperidol (a typical antipsychotic drug used for treating mental/mood disorders such as schizophrenia and bipolar disorder) suppress the viability of a variety of solid tumor cell lines, and we have identified 4-(4-(4-chlorophenyl)-1,4-diazepan-1-yl)-1-(4-fluoro-phenyl)butan-1-one (SYA013) with such antiproliferative properties. Interestingly, unlike haloperidol, SYA013 shows moderate selectivity toward σ2 receptors. In this study, we explored the potential of SYA013 in modulating the important biological events associated with cell survival and progression as well as the mechanistic aspects of apoptosis in a representative TNBC cell line (MDA-MB-231). Our results indicate that SYA013 inhibits the proliferation of MDA-MB-231 cells in a concentration-dependent manner and suppresses cell migration and invasion. Apoptotic studies were also conducted in MDA-MB-468 cells (cells derived from a 51-year old Black female with metastatic adenocarcinoma of the breast.). In addition, we have demonstrated that SYA013 induces MDA-MB-231 cell death through the intrinsic apoptotic pathway and may suppress tumor progression and metastasis. Taken together, our study presents a mechanistic pathway of the anticancer properties of SYA013 against TNBC cell lines and suggests a potential for exploring SYA013 as a lead agent for development against TNBC.

Towards understanding the evolutionary dynamics of mtDNA

Historically, mtDNA was considered a selectively neutral marker that was useful for estimating the population genetic history of the maternal lineage. Over time there has been an increasing appreciation of mtDNA and mitochondria in maintaining cellular and organismal health. Beyond energy production, mtDNA and mitochondria have critical cellular roles in signalling. Here we briefly review the structure of mtDNA and the role of the mitochondrion in energy production. We then discuss the predictions that can be obtained from quaternary structure modelling and focus on mitochondrial complex I. Complex I is the primary entry point for electrons into the electron transport system is the largest respiratory complex of the chain and produces about 40% of the proton flux used to synthesize ATP. A focus of the review is Drosophila's utility as a model organism to study the selective advantage of specific mutations. However, we note that the incorporation of insights from a multitude of systems is necessary to fully understand the range of roles that mtDNA has in organismal fitness. We speculate that dietary changes can illicit stress responses that influence the selective advantage of specific mtDNA mutations and cause spatial and temporal fluctuations in the frequencies of mutations. We conclude that developing our understanding of the roles mtDNA has in determining organismal fitness will enable increased evolutionary insight and propose we can no longer assume it is evolving as a strictly neutral marker without testing this hypothesis.

A fas apoptotic inhibitory molecule from Ruditapes philippinarum: Investigation on molecular characterization and functional analysis

In the present study, a fas apoptotic inhibitory molecule (FAIM) was identified from Ruditapes philippinarum (designated as RpFAIM). Multiple alignments and phylogenetic analysis strongly suggested that RpFAIM was a new member of the FAIMs family. The RpFAIM transcripts were constitutively expressed in a wide range of tissues, and dominantly expressed in hemocytes. After V. anguillarum or M. luteus challenge, the expression level of RpFAIM transcripts was significantly induced and reached the maximum level at 6 h and 24 h, respectively. Knockdown of RpFAIM down-regulated the transcript levels of NF-κB signaling genes (e.g. RpIKK, RpIκB, RpNF-κB). The results were roughly similar to those under bacterial stimulation. Moreover, RpFAIM primarily localized in the cell cytoplasm, and its over-expression inhibited the apoptosis of HeLa cells. These results revealed that RpFAIM perhaps regulated the NF-κB signaling pathways positively, which provided a better understanding of RpFAIM in innate immunity.

Mitochondria, the gut microbiome and ROS

In this review, we discuss the connections between mitochondria and the gut microbiome provided by reactive oxygen species (ROS). We examine the mitochondrion as an endosymbiotic organelle that is a hub for energy production, signaling, and cell homeostasis. Maintaining a diverse gut microbiome is generally associated with organismal fitness, intestinal health and resistance to environmental stress. In contrast, gut microbiome imbalance, termed dysbiosis, is linked to a reduction in organismal well-being. ROS are essential signaling molecules but can be damaging when present in excess. Increasing ROS levels have been shown to influence human health, homeostasis of gut cells, and the gastrointestinal microbial community's biodiversity. Reciprocally, gut microbes can affect ROS levels, mitochondrial homeostasis, and host health. We propose that mechanistic understanding of the suite of bi-directional interactions between mitochondria and the gut microbiome will facilitate innovative interdisciplinary studies examining evolutionary divergence and provide novel treatments and therapeutics for disease. GLOSS: In this review, we focus on the nexus between mitochondria and the gut microbiome provided by reactive oxygen species (ROS). Mitochondria are a cell organelle that is derived from an ancestral alpha-proteobacteria. They generate around 80% of the adenosine triphosphate that an organism needs to function and release a range of signaling molecules essential for cellular homeostasis. The gut microbiome is a suite of microorganisms that are commensal, symbiotic and pathogenic to their host. ROS are one predominant group of essential signaling molecules that can be harmful in excess. We suggest that the mitochondria- microbiome nexus is a frontier of research that has cross-disciplinary benefits in understanding genetic divergence and human well-being.

Regulation of Apoptosis by Enteroviruses

Enterovirus infection can cause a variety of diseases and severely impair the health of humans, animals, poultry, and other organisms. To resist viral infection, host organisms clear infected cells and viruses via apoptosis. However, throughout their long-term competition with host cells, enteroviruses have evolved a series of mechanisms to regulate the balance of apoptosis in order to replicate and proliferate. In the early stage of infection, enteroviruses mainly inhibit apoptosis by regulating the PI3K/Akt pathway and the autophagy pathway and by impairing cell sensors, thereby delaying viral replication. In the late stage of infection, enteroviruses mainly regulate apoptotic pathways and the host translation process via various viral proteins, ultimately inducing apoptosis. This paper discusses the means by which these two phenomena are balanced in enteroviruses to produce virus-favoring conditions – in a temporal sequence or through competition with each other. This information is important for further elucidation of the relevant mechanisms of acute infection by enteroviruses and other members of the picornavirus family.

BCL-2 family deregulation in colorectal cancer: potential for BH3 mimetics in therapy

Apoptosis is a form of programmed cell death that is essential for tissue homeostasis. De-regulation of the balance between proliferation and apoptosis contributes to tumor initiation. Particularly in the colon where apoptosis is a crucial process in intestinal turnover, inhibition of apoptosis facilitates transformation and tumor progression. The BCL-2 family of proteins are key regulators of apoptosis and have been implicated in colorectal cancer (CRC) initiation, progression and resistance to therapy. In this review we outline the current knowledge on the BCL-2 family-regulated intrinsic apoptosis pathway and mechanisms by which it is de-regulated in CRC. We further review BH3 mimetics as a therapeutic opportunity to target this pathway and evaluate their potential for CRC treatment.

Mitochondrial DNA in inflammation and immunity

Mitochondria are cellular organelles that orchestrate a vast range of biological processes, from energy production and metabolism to cell death and inflammation. Despite this seemingly symbiotic relationship, mitochondria harbour within them a potent agonist of innate immunity: their own genome. Release of mitochondrial DNA into the cytoplasm and out into the extracellular milieu activates a plethora of different pattern recognition receptors and innate immune responses, including cGAS‐STING, TLR9 and inflammasome formation leading to, among others, robust type I interferon responses. In this Review, we discuss how mtDNA can be released from the mitochondria, the various inflammatory pathways triggered by mtDNA release and its myriad biological consequences for health and disease.

Cell membrane-coated gold nanoparticles for apoptosis imaging in living cells based on fluorescent determination

A nanoprobe was developed to achieve apoptosis detection by cell membrane-functionalized gold nanoparticles (AuNP-pep@Mem). The fluorescence of the fluorescein isothiocyanate isomer I (FITC)-labeled caspase-3 substrates was quenched by the attachment to AuNPs. The fluorescence signal was recovered via the cleavage of caspase-3 under apoptotic conditions. It exhibited a low detection limit of 1.3 pg·mL^-1 with a linear range from 3.2 to 100 pg·mL^-1 for caspase-3 detection with excitation wavelength of 490 nm. After wrapped by the cell membrane, the nanoprobe was effectively delivered into cells with high cell permeability. AuNP-pep@Mem nanoprobe provided signal enhancement of 1.8 times in living cells compared to non-membrane-coated nanoparticles (AuNP-pep). In combination with its excellent stability, low LOD and good specificity, the AuNP-pep@Mem probe can be an ideal probe for fluorescence imaging of apoptosis. Graphical abstractSchematic representation of fluorescent determination for apoptosis in living cells based on cell membrane-coated gold nanoparticls.

Effect of autophagy induction and cathepsin B inhibition on developmental competence of poor quality bovine oocytes

The present study investigated the effect of autophagy induction and cathepsin B (CTSB) inhibition on developmental competence of poor quality oocytes. Bovine cumulus oocyte complexes (COCs) were classified as good or poor according to their morphology. Autophagy activity was detected in good and poor germinal vesicle (GV) oocytes. Then E-64, a CTSB inhibitor, rapamycin (Rapa), an autophagy inducer, and combined administration was achieved during in vitro maturation (IVM) of poor quality COCs followed by detection of autophagy activity. In the next experiment, E-64, Rapa, and E64 + Rapa, were added during IVM to good and poor quality COCs followed by in vitro fertilization and culture for 8 days to investigate whether inhibition of CTSB and/or induction of autophagy improve embryonic development and quality. Autophagy activity was significantly lower in poor quality GV oocytes than in good quality ones. E-64, Rapa and E-64 + Rapa treatment during IVM significantly increased autophagy activity in poor quality oocytes. Addition of Rapa in good quality COCs did not increase the blastocyst rate, whereas E-64 increased the blastocyst rate and total cell number (TCN) with decreasing TUNEL-positive cells. In contrast, Rapa treatment in poor quality COCs significantly increased the blastocyst rate and TCN with decreasing TUNEL-positive cells. These results indicate oocyte quality has different responses to intracellular autophagy induction and CTSB activity control by potential autophagy and catabolic status, however, synergetic effect of autophagy induction and CTSB inhibition can increase developmental competence of both good and poor quality COCs, especially rescue effect in poor quality COCs.

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.

Teleost Gasdermin E Is Cleaved by Caspase 1, 3, and 7 and Induces Pyroptosis

Pyroptosis is a newly defined gasdermin (GSDM)-dependent inflammatory type of programmed cell death. Different from mammals, which have a panel of pyroptotic GSDM members (e.g., GSDMA-E), teleosts possess only GSDME. The pyroptotic activity and regulation mechanism of teleost GSDME remain to be elucidated. In this work, we investigated the activity of the teleost Cynoglossus semilaevis (tongue sole) GSDME (CsGSDME) in association with different caspases (CASPs). We found that CsGSDME exerted pyroptotic and bactericidal activities through its N-terminal domain. Unlike human GSDME, which is exclusively cleaved by CASP3, CsGSDME was cleaved by C. semilaevis CASP (CsCASP) 1 with high efficiency and by CsCASP3 and 7 with comparatively low efficiencies, and all cleavages occurred at the ₂₄₃FEVD₂₄₆ site in the interdomain linker region of CsGSDME. Mutation of Phe²⁴³ to Asp/Ala and Asp²⁴⁶ to Ala in ₂₄₃FEVD₂₄₆ altered the cleavage preference of CsCASP1, 3, and 7. Treatment with loss-of-function CsCASP mutants or inhibition of CsCASP activity resulted in failure of CsGSDME cleavage. CsCASP1-cleaved CsGSDME induced pyroptosis, whereas CsCASP3/7-cleaved CsGSDME and F243 mutants induced switching of cell death from apoptosis to pyroptosis. Analysis of 54 teleost GSDME sequences revealed a conserved tetrapeptide motif that fits well to the inherent cleavage site of CASP1. Taken together, the results of our study demonstrate a hitherto, to our knowledge, unrecognized GSDME cleavage mode in teleosts that is clearly different from that in mammals, thus providing an important insight into the activation mechanism of CASP-mediated, GSDM-executed pyroptosis in teleosts.

Selenoprotein S protects against high glucose-induced vascular endothelial apoptosis through the PKCβII/JNK/Bcl-2 pathway

Vascular endothelial apoptosis is closely associated with the pathogenesis and progression of diabetic macrovascular diseases. Selenoprotein S (SelS) participates in the protection of vascular endothelial and smooth muscle cells from oxidative and endoplasmic reticulum stress-induced injury. However, whether SelS can protect vascular endothelium from high glucose (HG)-induced apoptosis and the underlying mechanism remains unclear. The present study preliminarily analyzed aortic endothelial apoptosis and SelS expression in diabetic rats in vivo and the effects of HG on human umbilical vein endothelial cell (HUVEC) apoptosis and SelS expression in vitro. Subsequently, SelS expression was up- or downregulated in HUVECs using the pcDNA3.1-SelS recombinant plasmid and SelS-specific small interfering RNAs, and the effects of high/low SelS expression on HG-induced HUVEC apoptosis and a possible molecular mechanism were analyzed. As expected, HG induced vascular endothelial apoptosis and upregulated endothelial SelS expression in vivo and in vitro. SelS overexpression in HUVECs suppressed HG-induced increase in apoptosis and cleaved caspase3 level, accompanied by reduced protein kinase CβII (PKCβII), c-JUN N-terminal kinase (JNK), and B-cell lymphoma/leukemia-2 (Bcl-2) phosphorylation. In contrast, inhibiting SelS expression in HUVECs further aggravated HG-induced increase in apoptosis and cleaved caspase3 level, which was accompanied by increased PKCβII, JNK, and Bcl-2 phosphorylation. Pretreatment with PKC activators blocked the protective effects of SelS and increased the apoptosis and cleaved caspase3 level in HUVECs. In summary, SelS protects vascular endothelium from HG-induced apoptosis, and this was achieved through the inhibition of PKCβII/JNK/Bcl-2 pathway to eventually inhibit caspase3 activation. SelS may be a promising target for the prevention and treatment of diabetic macrovascular complications.