Apaf-1, a human protein homologous to C. elegans CED-4, participates in cytochrome c-dependent activation of caspase-3

Less is better: various means to reduce protein load in the endoplasmic reticulum

The endoplasmic reticulum (ER) is an important organelle that controls the intracellular and extracellular environments. The ER is responsible for folding almost one-third of the total protein population in the eukaryotic cell. Disruption of ER-protein folding is associated with numerous human diseases, including metabolic disorders, neurodegenerative diseases, and cancer. During ER perturbations, the cells deploy various mechanisms to increase the ER-folding capacity and reduce ER-protein load by minimizing the number of substrates entering the ER to regain homeostasis. These mechanisms include signaling pathways, degradation mechanisms, and other processes that mediate the reflux of ER content to the cytosol. In this review, we will discuss the recent discoveries of five different ER quality control mechanisms, including the unfolded protein response (UPR), ER-associated-degradation (ERAD), pre-emptive quality control, ER-phagy and ER to cytosol signaling (ERCYS). We will discuss the roles of these processes in decreasing ER-protein load and inter-mechanism crosstalk.

A structural atlas of death domain fold proteins reveals their versatile roles in biology and function

Death domain fold (DDF) superfamily proteins are critically important players in pathways of cell death and inflammation. DDFs are often essential scaffolding domains in receptors, adaptors, or effectors of these pathways by mediating homo- and hetero-oligomerization including helical filament assembly. At the downstream ends of these pathways, effector oligomerization by DDFs brings the enzyme domains into proximity for their dimerization and activation. Hundreds of structures of these domains have been solved. However, a comprehensive understanding of DDFs is lacking. In this article, we report the curation of a DDF structural atlas as a public website (deathdomain.org) and deduce the common and distinct principles of DDF-mediated oligomerization among the four families (death domain or DD, death effector domain or DED, caspase recruitment domain or CARD, and pyrin domain or PYD). We further annotate DDFs genome-wide based on AlphaFold-predicted models and protein sequences. These studies reveal mechanistic rules for this widely distributed domain superfamily.

Caspases in PANoptosis

Recent studies prove that the three well-established cell death pathways-pyroptosis, apoptosis, and necroptosis-are not isolated but rather engage in extensive crosstalk. PANoptosis, a newly identified pathway of inflammatory regulated cell death (RCD), integrates characteristics of apoptosis, pyroptosis, and necroptosis. Caspases are a family of conserved cysteine proteases that play critical roles in pyroptosis, apoptosis, and necroptosis. Similarly, caspases also play a role in PANoptosis. In this paper, we review the molecular mechanisms of these three RCDs and the crosstalk between them. We also delineate the discovery of PANoptosis and its association with disease. Furthermore, we discuss the caspase function in PANoptosis, mainly focusing on caspase-6 and caspase-8 molecules. This review describes the key molecules, especially caspases, in the context of PANoptosis research, aiming to provide a foundation for targeted interventions in PANoptosis-associated diseases.

Apoptosis in polycystic ovary syndrome: Mechanisms and therapeutic implications

Polycystic ovary syndrome (PCOS) is a common disorder that affects the female reproductive system, with an incidence of 8 % to 15 %. It is characterized by irregular menstruation, hyperandrogenemia, and polycystic abnormalities in the ovaries. Nevertheless, there is still much to learn about the molecular pathways underlying PCOS. Apoptosis is the process by which cells actively destroy themselves, and it is vital to an organism's ability to develop normally and maintain homeostasis. In recent years, a growing body of research has indicated a connection between the pathophysiology of PCOS and apoptosis. Therefore, it is critical to comprehend the relationship between PCOS and apoptosis in greater detail, identify the pathophysiological underpinnings of PCOS, and provide fresh perspectives and targets for its treatment. This review aims to summarize the relationship between PCOS and apoptosis, discuss how apoptosis affects normal ovarian function and how it becomes dysfunctional in the ovaries of PCOS patients, and investigate the signaling pathways associated with apoptosis in PCOS, including PI3K-Akt, TNF, NF-κB, and p53. Additionally, potential therapeutic approaches for PCOS treatment are provided by summarizing the role of apoptosis in PCOS therapy.

Integrative analysis of m7G methylation-associated genes prognostic signature with immunotherapy and identification of LARP1 as a key oncogene in head and neck squamous cell carcinoma

Background

N7-methylguanosine (m7G) methylation is an RNA modification associated with cancer progression, but its specific role in head and neck squamous cell carcinoma (HNSCC) remains unclear.

Methods

This study analyzed the differential expression of m7G-related genes (m7GRGs) in HNSCC using the TCGA-HNSCC dataset, identifying key pathways associated with the cell cycle, DNA replication, and focal adhesion. A LASSO-Cox regression model was constructed based on four m7GRGs (EIF3D, EIF1, LARP1, and METTL1) and validated with GEO datasets and clinical samples. Further validation of gene upregulation in HNSCC tissues was conducted using RT-qPCR and immunohistochemistry, while the role of LARP1 in HNSCC cells was assessed via knockout experiments.

Results

The constructed model demonstrated strong predictive performance, with the risk score significantly correlating with prognosis, immune infiltration, and drug sensitivity. An external dataset and clinical specimens further confirmed the model's predictive accuracy for immunotherapy response. Additionally, two regulatory axes-LINC00707/hsa-miR-30b-5p/LARP1 and SNHG16/hsa-miR-30b-5p/LARP1-were identified. LARP1 knockout experiments revealed that suppressing LARP1 markedly inhibited HNSCC cell proliferation, migration, and invasion.

Conclusion

The m7GRG-based prognostic model developed in this study holds strong clinical potential for predicting prognosis and therapeutic responses in HNSCC. The identification of LARP1 and its related regulatory pathways offers new avenues for targeted therapy in HNSCC.

Apaf-1 is an evolutionarily conserved DNA sensor that switches the cell fate between apoptosis and inflammation

Apoptotic protease activating factor 1 (Apaf-1) was traditionally defined as a scaffold protein in mammalian cells for assembling a caspase activation platform known as the 'apoptosome' after its binding to cytochrome c. Although Apaf-1 structurally resembles animal NOD-like receptor (NLR) and plant resistance (R) proteins, whether it is directly involved in innate immunity is still largely unknown. Here, we found that Apaf-1-like molecules from lancelets, fruit flies, mice, and humans have conserved DNA sensing functionality. Mechanistically, mammalian Apaf-1 recruits receptor-interacting protein 2 (RIP2, also known as RIPK2) via its WD40 repeat domain and promotes RIP2 oligomerization to initiate NF-κB-driven inflammation upon cytoplasmic DNA recognition. Furthermore, DNA binding of Apaf-1 determines cell fate by switching the cellular processes between intrinsic stimuli-activated apoptosis and inflammation. These findings suggest that Apaf-1 is an evolutionarily conserved DNA sensor and may serve as a cell fate checkpoint, which determines whether cells initiate inflammation or undergo apoptosis by distinct ligand binding.

EOR-1/PLZF-regulated WAH-1/AIF sequentially promotes early and late stages of non-apoptotic corpse removal

Programmed cell death (PCD) is a crucial, genetically-encoded, and evolutionarily-conserved process required for development and homeostasis. We previously identified a genetically non-apoptotic, highly ordered, and stereotyped killing program called Compartmentalized Cell Elimination (CCE) in the C. elegans tail-spike epithelial cell (TSC). Here we identify the transcription factor EOR-1/PLZF as an important coordinator of CCE. Loss of EOR-1 results in a large, persisting, un-engulfed soma with enlarged nuclei. We find that EOR-1 and its partners positively regulate the transcription of the Apoptosis Inducing Factor AIF homolog, WAH-1/AIF. We report stereotyped and sequential spatiotemporal dynamics of WAH-1/AIF1 during phagocytosis, with defined roles acting early and late, within the dying cells. Mitochondria to plasma membrane translocation within the TSC soma is required its internalization by its phagocyte, and plasma membrane to nuclear translocation is required for DNA degradation and ultimately, corpse resolution. Our study suggests that EOR-1 serves as a master regulator for the transcriptional control of DNA degradation is essential for changes in nuclear morphology required for cellular dismantling and infers that tight spatiotemporal regulation of WAH-1/AIF is required for this function.

PANoptosis in intestinal epithelium: its significance in inflammatory bowel disease and a potential novel therapeutic target for natural products

The intestinal epithelium, beyond its role in absorption and digestion, serves as a critical protective mechanical barrier that delineates the luminal contents and the gut microbiota from the lamina propria within resident mucosal immune cells to maintain intestinal homeostasis. The barrier is manifested as a contiguous monolayer of specialized intestinal epithelial cells (IEC), interconnected through tight junctions (TJs). The integrity of this epithelial barrier is of paramount. Consequently, excessive IEC death advances intestinal permeability and as a consequence thereof the translocation of bacteria into the lamina propria, subsequently triggering an inflammatory response, which underpins the clinical disease trajectory of inflammatory bowel disease (IBD). A burgeoning body of evidence illustrates a landscape where IEC undergoes several the model of programmed cell death (PCD) in the pathophysiology and pathogenesis of IBD. Apoptosis, necroptosis, and pyroptosis represent the principal modalities of PCD with intricate specific pathways and molecules. Ample evidence has revealed substantial mechanistic convergence and intricate crosstalk among these three aforementioned forms of cell death, expanding the conceptualization of PANoptosis orchestrated by the PNAoptosome complex. This review provides a concise overview of the molecular mechanisms of apoptosis, necroptosis, and pyroptosis. Furthermore, based on the crosstalk between three cell deaths in IEC, this review details the current knowledge regarding PANoptosis in IEC and its regulation by natural products. Our objective is to broaden the comprehension of innovative molecular mechanisms underlying the pathogenesis of IBD and to furnish a foundation for developing more natural drugs in the treatment of IBD, benefiting both clinical practitioners and research workers.

Korean Red ginseng enhances ZBP1-mediated cell death to suppress viral protein expression in host defense against Influenza A virus

Korean Red ginseng has emerged as a potent candidate in the fight against various viral infections, demonstrating significant efficacy both in vitro and in vivo, particularly against influenza A viruses. Despite substantial evidence of its antiviral properties, the detailed molecular mechanisms through which it reduces viral lethality remain insufficiently understood. Our investigations have highlighted the superior effectiveness of Korean Red ginseng against influenza viruses, outperforming its effects on numerous other viral strains. We aim to uncover the specific mechanisms by which Korean Red ginseng exerts its antiviral effects, focusing on influenza A viruses. Our prior studies have identified the role of Z-DNA-binding protein 1 (ZBP1), a signaling complex involved in inducing programmed cell death in response to influenza virus infection. Given the critical role of ZBP1 as a sensor for viral nucleic acid, we hypothesize that Korean Red ginseng may modulate the ZBP1-derived cell death pathway. This interaction is anticipated to enhance cell death while concurrently suppressing viral protein expression, offering novel insights into the antiviral mechanism of Korean Red ginseng against influenza A viruses.

Predictive models of sarcopenia based on inflammation and pyroptosis-related genes

Background

Sarcopenia is a prevalent condition associated with aging. Inflammation and pyroptosis significantly contribute to sarcopenia.

Methods

Two sarcopenia-related datasets (GSE111016 and GSE167186) were obtained from the Gene Expression Omnibus (GEO), followed by batch effect removal post-merger. The "limma" R package was utilized to identify differentially expressed genes (DEGs). Subsequently, LASSO analysis was conducted on inflammation and pyroptosis-related genes (IPRGs), resulting in the identification of six hub IPRGs. A novel skeletal muscle aging model was developed and validated using an independent dataset. Additionally, Gene Ontology (GO) enrichment analysis was performed on DEGs, along with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and gene set enrichment analysis (GSEA). ssGSEA was employed to assess differences in immune cell proportions between healthy muscle groups in older versus younger adults. The expression levels of the six core IPRGs were quantified via qRT-PCR.

Results

A total of 44 elderly samples and 68 young healthy samples were analyzed for DEGs. Compared to young healthy muscle tissue, T cell infiltration levels in aged muscle tissue were significantly reduced, while mast cell and monocyte infiltration levels were relatively elevated. A new diagnostic screening model for sarcopenia based on the six IPRGs demonstrated high predictive efficiency (AUC = 0.871). qRT-PCR results indicated that the expression trends of these six IPRGs aligned with those observed in the database.

Conclusion

Six biomarkers-BTG2, FOXO3, AQP9, GPC3, CYCS, and SCN1B-were identified alongside a diagnostic model that offers a novel approach for early diagnosis of sarcopenia.

Cytochrome c and cancer cell metabolism: A new perspective

Cytochrome c is a vital electron carrier in the mitochondrial respiratory chain. When the outer membrane of mitochondria becomes permeable, cytochrome c is discharged into the cytoplasm, where it initiates the intrinsic apoptosis pathway. The complex interaction between cytochrome c and apoptosis protease-activating factor-1 (Apaf-1) leads to the formation of the apoptosome and activation of a cascade of caspases, highlighting the critical role of cytochrome c in controlling cell death mechanisms. Additionally, cytochrome c undergoes post-translational modifications, especially phosphorylation, which intricately regulate its roles in both respiration and apoptosis. These modifications add layers of complexity to how cytochrome c effectively controls cellular functions. cytochrome c becomes a lighthouse in the intricate web of cancer, its expression patterns providing hints about prognosis and paths toward treatment. Reduced levels of cytochrome c have been observed in cancer tissues, indicating a potential inhibition of apoptosis. For instance, in glioma tissues, cytochrome c levels were lower compared to healthy tissues, and this reduction became more pronounced in advanced stages of the disease. However, the role of cytochrome c in cancer becomes more intricate as it becomes intertwined with the metabolic reprogramming of cancer cells. This suggests that cytochrome c plays a crucial role in tumor progression and resistance to treatment. Viewing cytochrome c as a molecular mosaic reveals that it is not merely a protein, but also a central player in determining cellular fate. This realization opens up exciting avenues for potential advancements in cancer diagnosis and treatment strategies. Despite the advancements made, the narrative surrounding cytochrome c remains incomplete, urging further exploration into its complexities and the biological implications linked to cancer. cytochrome c stands as a beacon of hope and a promising target for therapy in the battle against cancer, particularly due to its significant involvement in tumor metabolism. It holds the potential for a future where innovative solutions can be developed to address the intricate challenges of cellular fate. In this review, we have endeavored to illuminate the multifaceted domain of cytochrome c drawing connections among apoptosis, metabolic reprogramming, and the Warburg effect in the context of cancer.

Unique structural configuration of EV-DNA primes Kupffer cell-mediated antitumor immunity to prevent metastatic progression

Extracellular vesicles (EVs) transport biomolecules that mediate intercellular communication. We previously showed that EVs contain DNA (EV-DNA) representing the entire genome. However, the mechanism of genomic EV-DNA packaging and its role in cancer remain elusive. We now demonstrate that EV-DNA is predominantly localized on the vesicle surface and associated with uniquely modified and cleaved histones. Moreover, a genome-wide clustered regularly interspaced short palindromic repeats knockout screen revealed that immune developmental pathways and genes, including apoptotic peptidase activating factor 1 (APAF1) and neutrophil cytosolic factor 1 (NCF1), regulate EV-DNA packaging. Furthermore, in colorectal cancer models, uptake of EV-DNA by pre-metastatic liver Kupffer cells (KCs) activated DNA damage responses. This activation rewired KC cytokine production and promoted the formation of tertiary lymphoid structures, thereby suppressing liver metastasis. Conversely, loss of APAF1 decreased EV-DNA packaging and promoted liver metastasis. Importantly, colorectal cancer biopsy EV-DNA secretion could serve as a predictive biomarker for postoperative metastasis. Taken together, our findings indicate that uniquely chromatinized EV-DNA induces antitumor immunity.

Identification of a postnatal period of interdependent neurogenesis and apoptosis in peripheral neurons

During neurogenesis, excessive numbers of neurons are produced in most regions of the central and peripheral nervous systems. Nonessential neurons are eliminated by apoptosis, or programmed cell death. This has been most thoroughly characterized in the peripheral nervous system (PNS) where targets of innervation play a key role in this process. As maturing neurons project axons towards their targets of innervation, they become dependent upon these targets for survival. Survival factors, also called neurotrophic factors, are produced by targets, inhibit apoptosis cascades, and promote further growth and differentiation. Because neurotrophic factors are limited, as is target size, neurons that do not correctly and efficiently innervate targets undergo apoptosis ( Levi-Montalcini, 1987; Davies, 1996). Thus, excessive neurogenesis acts to ensure that sufficient numbers of neurons are produced during development. In the superior cervical ganglion (SCG), this process of neurogenesis and subsequent apoptosis is reported to be complete by postnatal day 3-4 (P3-P4) in mice. Surprisingly, we observed significant numbers of apoptotic neurons out to P14, and neurogenesis was still present at P14 as well. In both the SCG and geniculate ganglion (GG), postnatal neurogenesis was dependent on apoptosis because little or no postnatal neurogenesis was observed in Bax-/- mice, in which apoptosis is eliminated. These results indicate that both neurogenesis and apoptosis continue to occur well after birth in peripheral ganglia, and that neurogenesis depends on apoptosis, suggesting that neurogenesis continues postnatally to replace neurons that are eliminated during synaptic refinement.

The pro-apoptotic function of the C. elegans BCL-2 homolog CED-9 requires interaction with the APAF-1 homolog CED-4

In Caenorhabditis elegans, apoptosis is inhibited by the BCL-2 homolog CED-9. Although canonically anti-apoptotic, CED-9 has a poorly understood pro-apoptotic function. CED-9 is thought to inhibit apoptosis by binding to and inhibiting the pro-apoptotic C. elegans APAF-1 homolog CED-4. We show that CED-9 or CED-4 mutations located in their CED-9-CED-4 binding regions reduce apoptosis without affecting the CED-9 anti-apoptotic function. These mutant CED-9 and CED-4 proteins are defective in a CED-9-CED-4 interaction in vitro and in vivo, revealing that the known CED-9-CED-4 interaction is required for the pro-apoptotic but not for the anti-apoptotic function of CED-9. The pro-apoptotic CED-9-CED-4 interaction occurs at mitochondria. In mammals, BCL-2 family members can activate APAF-1 via cytochrome c release from mitochondria. The conserved role of mitochondria in CED-9/BCL-2-dependent CED-4/APAF-1 activation is notable and suggests that understanding how CED-9 promotes apoptosis in C. elegans could inform the understanding of mammalian apoptosis and how disruptions of apoptosis promote certain human disorders.

Evolution of Apoptotic Signaling Pathways Within Lophotrochozoans

Apoptosis is the main form of regulated cell death in metazoans. Apoptotic pathways are well characterized in nematodes, flies, and mammals, leading to a vision of the conservation of apoptotic pathways in metazoans. However, we recently showed that intrinsic apoptosis is in fact divergent among metazoans. In addition, extrinsic apoptosis is poorly studied in non-mammalian animals, making its evolution unclear. Consequently, our understanding of apoptotic signaling pathways evolution is a black box which must be illuminated by extending research to new biological systems. Lophotrochozoans are a major clade of metazoans which, despite their considerable biological diversity and key phylogenetic position as sister group of ecdysozoans (i.e. flies and nematodes), are poorly explored, especially regarding apoptosis mechanisms. Traditionally, each apoptotic signaling pathway was considered to rely on a specific initiator caspase, associated with an activator. To shed light on apoptosis evolution in animals, we explored the evolutionary history of initiator caspases, caspase activators, and the BCL-2 family (which control mitochondrial apoptotic pathway) in lophotrochozoans using phylogenetic analysis and protein interaction predictions. We discovered a diversification of initiator caspases in molluscs, annelids, and brachiopods, and the loss of key extrinsic apoptosis components in platyhelminths, along with the emergence of a clade-specific caspase with an ankyrin pro-domain. Taken together, our data show a specific history of apoptotic actors' evolution in lophotrochozoans, further demonstrating the appearance of distinct apoptotic signaling pathways during metazoan evolution.

Combining Photodynamic Therapy and Targeted Drug Delivery Systems: Enhancing Mitochondrial Toxicity for Improved Cancer Outcomes

Cancer treatment continues to be a substantial problem due to tumor complexities and persistence, demanding novel therapeutic techniques. This review investigates the synergistic potential of combining photodynamic therapy (PDT) and tailored medication delivery technologies to increase mitochondrial toxicity and improve cancer outcomes. PDT induces selective cellular damage and death by activating photosensitizers (PS) with certain wavelengths of light. However, PDT's efficacy can be hampered by issues such as poor light penetration and a lack of selectivity. To overcome these challenges, targeted drug delivery systems have emerged as a promising technique for precisely delivering therapeutic medicines to tumor cells while avoiding off-target effects. We investigate how these technologies can improve mitochondrial targeting and damage, which is critical for causing cancer cell death. The combination method seeks to capitalize on the advantages of both modalities: selective PDT activation and specific targeted drug delivery. We review current preclinical and clinical evidence supporting the efficacy of this combination therapy, focusing on case studies and experimental models. This review also addresses issues such as safety, distribution efficiency, resistance mechanisms, and costs. The prospects of further research include advances in photodynamic agents and medication delivery technology, with a focus on personalized treatment. In conclusion, combining PDT with targeted drug delivery systems provides a promising frontier in cancer therapy, with the ability to overcome current treatment limits and open the way for more effective, personalized cancer treatments.

Dynamic death decisions: How mitochondrial dynamics shape cellular commitment to apoptosis and ferroptosis

The incorporation of mitochondria into early eukaryotes established organelle-based biochemistry and enabled metazoan development. Diverse mitochondrial biochemistry is essential for life, and its homeostatic control via mitochondrial dynamics supports organelle quality and function. Mitochondrial crosstalk with numerous regulated cell death (RCD) pathways controls the decision to die. In this review, we will focus on apoptosis and ferroptosis, two distinct forms of RCD that utilize divergent signaling to kill a targeted cell. We will highlight how proteins and processes involved in mitochondrial dynamics maintain biochemically diverse subcellular compartments to support apoptosis and ferroptosis machinery, as well as unite disparate RCD pathways through dual control of organelle biochemistry and the decision to die.

Exploring the Effects of S-Nitrosylation on Caspase-3 Modification and Myofibril Degradation of Beef In Vitro

This study aimed to explore the effects of S-nitrosylation on caspase-3 modification and its subsequent effects on beef myofibril degradation in vitro. Recombinant caspase-3 was reacted with different concentrations of S-nitrosoglutathione (GSNO, nitric oxide donor) at 37 °C for 30 min and subsequently incubated with purified myofibrillar protein from bovine semimembranosus muscle. Results indicated that the activity of caspase-3 was significantly reduced after GSNO treatments (P < 0.05) and showed a dose-dependent inhibitory effect, which was attributed to the increased S-nitrosylation extent of caspase-3. LC-MS/MS analysis revealed that caspase-3 was S-nitrosylated at cysteine sites 116, 170, 184, 220, and 264. Moreover, the degradation of desmin and troponin-T was notably suppressed by S-nitrosylated caspase-3 (P < 0.05). To conclude, protein S-nitrosylation could modify the cysteine residues of caspase-3, which accounts for the reduced caspase-3 activity and further represses its proteolytic ability on beef myofibrillar protein.

Phosphorylation of caspases by a bacterial kinase inhibits host programmed cell death

The intracellular bacterial pathogen Legionella pneumophila utilizes the Dot/Icm system to translocate over 330 effectors into the host cytosol. These virulence factors modify a variety of cell processes, including pathways involved in cell death and survival, to promote bacterial proliferation. Here, we show that the effector LegK3 is a eukaryotic-like Ser/Thr kinase that functions to suppress host apoptosis. Mechanistically, LegK3 directly phosphorylates multiple caspases involved in apoptosis signaling, including Caspase-3, Caspase-7, and Caspase-9. LegK3-induced phosphorylation of these caspases occurs at serine (Ser29 in Caspase-3 and Ser199 in Caspase-7) or threonine (Thr102 in Caspase-9) residues located in the prodomain or interdomain linkers. These modifications interfere with the suitability of the caspases as the substrates of initiator caspases or upstream regulators without impacting their proteolytic activity. Collectively, our study reveals a novel strategy used by L. pneumophila to maintain the integrity of infected cells for its intracellular growth.

Transplantation of astrocyte-derived mitochondria into injured astrocytes has a protective effect following stretch injury

Traumatic brain injury (TBI) is a global public-health problem. Astrocytes, and their mitochondria, are important factors in the pathogenesis of TBI-induced secondary injury. Mitochondria extracted from healthy tissues and then transplanted have shown promise in models of a variety of diseases. However, the effect on recipient astrocytes is unclear. Here, we isolated primary astrocytes from newborn C57BL/6 mice, one portion of which was used to isolate mitochondria, and another was subjected to stretch injury (SI) followed by transplantation of the isolated mitochondria. After incubation for 12 h, cell viability, mitochondrial dysfunction, calcium overload, redox stress, inflammatory response, and apoptosis were improved. Live-cell imaging showed that the transplanted mitochondria were incorporated into injured astrocytes and fused with their mitochondrial networks, which was in accordance with the changes in the expression levels of markers of mitochondrial dynamics. The astrocytic IKK/NF-κB pathway was decelerated whereas the AMPK/PGC-1α pathway was accelerated by transplantation. Together, these results indicate that exogenous mitochondria from untreated astrocytes can be incorporated into injured astrocytes and fuse with their mitochondrial networks, improving cell viability by ameliorating mitochondrial dysfunction, redox stress, calcium overload, and inflammation.

Microglia-induced neuroinflammation in hippocampal neurogenesis following traumatic brain injury

Traumatic brain injury (TBI) is one of the most causes of death and disability among people, leading to a wide range of neurological deficits. The important process of neurogenesis in the hippocampus, which includes the production, maturation and integration of new neurons, is affected by TBI due to microglia activation and the inflammatory response. During brain development, microglia are involved in forming or removing synapses, regulating the number of neurons, and repairing damage. However, in response to injury, activated microglia release a variety of pro-inflammatory cytokines, chemokines and other neurotoxic mediators that exacerbate post-TBI injury. These microglia-related changes can negatively affect hippocampal neurogenesis and disrupt learning and memory processes. To date, the intracellular signaling pathways that trigger microglia activation following TBI, as well as the effects of microglia on hippocampal neurogenesis, are poorly understood. In this review article, we discuss the effects of microglia-induced neuroinflammation on hippocampal neurogenesis following TBI, as well as the intracellular signaling pathways of microglia activation.

Unveiling the Multifaceted Role of CIDEB: From Apoptosis to Lipid Metabolism and Liver Health

Cell-death-inducing DNA fragmentation factor-alpha (DFFA)-like effector b (CIDEB) was first identified as an apoptosis-inducing protein. Further research revealed a pivotal role in lipid metabolism, regulating very-low-density lipoprotein (VLDL), lipid droplets (LD), sterol response element-binding protein (SREBP), and chylomicrons. Recent studies have uncovered that rare germline variants in CIDEB protect against liver diseases, including MAFLD, cirrhosis, and viral hepatitis. Furthermore, CIDEB influences steps of the hepatitis C virus (HCV) replication cycle. This review summarizes the current knowledge about CIDEB’s roles in apoptosis, lipid metabolism, and viral hepatitis, and highlights its critical role in liver diseases.

No Time to Die: How Cytomegaloviruses Suppress Apoptosis, Necroptosis, and Pyroptosis

Viruses are obligate intracellular pathogens as their replication depends on the metabolism of the host cell. The induction of cellular suicide, known as programmed cell death (PCD), has the potential to hinder viral replication and act as a first line of defense against viral pathogens. Apoptosis, necroptosis, and pyroptosis are three important PCD modalities. Different signaling pathways are involved in their execution, and they also differ in their ability to cause inflammation. Cytomegaloviruses (CMV), beta-herpesviruses with large double-stranded DNA genomes, encode a great variety of immune evasion genes, including several cell death suppressors. While CMV inhibitors of apoptosis and necroptosis have been known and studied for years, the first pyroptosis inhibitor has been identified and characterized only recently. Here, we describe how human and murine CMV interfere with apoptosis, necroptosis, and pyroptosis signaling pathways. We also discuss the importance of the different PCD forms and their viral inhibitors for the containment of viral replication and spread in vivo.

The protective mechanism of human umbilical cord mesenchymal stem cell-derived exosomes against neutrophil extracellular trap-induced placental damage

INTRODUCTION

Preeclampsia (PE) is a pregnancy-specific complication. Its etiology and pathogenesis remain unclear. Previous studies have shown that neutrophil extracellular traps (NETs) cause placental dysfunction and lead to PE. Human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-EXOs) have been widely used to treat different diseases. We investigated whether hUCMSC-EXOs can protect against NET-induced placental damage.

METHODS

NETs were detected in the placenta by immunofluorescence. The impact of NETs on cellular function and the effect of hUCMSC-EXOs on NET-induced placental damage were evaluated by 5-ethynyl-20-deoxyuridine (EdU) cell proliferation, lactate dehydrogenase (LDH), reactive oxygen species (ROS), and cell migration, invasion and tube formation assays; flow cytometry; and Western blotting.

RESULTS

The number of placental NETs was increased in PE patients compared with control individuals. NETs impaired the function of endothelial cells and trophoblasts. These effects were partially reversed after N-acetyl-L-cysteine (NAC; ROS inhibitor) or DNase I (NET lysing agent) pretreatment. HUCMSC-EXOs ameliorated NET-induced functional impairment of endothelial cells and trophoblasts in vitro, partially reversed NET-induced inhibition of endothelial cell and trophoblast proliferation, and partially restored trophoblast migration and invasion and endothelial cell tube formation. Exosomes inhibited ROS production in these two cell types, suppressed p38 mitogen-activated protein kinase (p38 MAPK) signaling activation, activated extracellular signal-regulated kinase 1/2 (ERK1/2) signaling, and modulated the Bax, Bim, Bcl-2 and cleaved caspase-3 levels to inhibit apoptosis.

DISCUSSION

HUCMSC-EXOs can reverse NET-induced placental endothelial cell and trophoblast damage, possibly constituting a theoretical basis for the treatment of PE with exosomes.

Canonical and Noncanonical Functions of the BH3 Domain Protein Bid in Apoptosis, Oncogenesis, Cancer Therapeutics, and Aging

Effective cancer therapy with limited adverse effects is a major challenge in the medical field. This is especially complicated by the development of acquired chemoresistance. Understanding the mechanisms that underlie these processes remains a major effort in cancer research. In this review, we focus on the dual role that Bid protein plays in apoptotic cell death via the mitochondrial pathway, in oncogenesis and in cancer therapeutics. The BH3 domain in Bid and the anti-apoptotic mitochondrial proteins (Bcl-2, Bcl-XL, mitochondrial ATR) it associates with at the outer mitochondrial membrane provides us with a viable target in cancer therapy. We will discuss the roles of Bid, mitochondrial ATR, and other anti-apoptotic proteins in intrinsic apoptosis, exploring how their interaction sustains cellular viability despite the initiation of upstream death signals. The unexpected upregulation of this Bid protein in cancer cells can also be instrumental in explaining the mechanisms behind acquired chemoresistance. The stable protein associations at the mitochondria between tBid and anti-apoptotic mitochondrial ATR play a crucial role in maintaining the viability of cancer cells, suggesting a novel mechanism to induce cancer cell apoptosis by freeing tBid from the ATR associations at mitochondria.

Mechanistic evaluation of myristicin on apoptosis and cell cycle regulation in breast cancer cells

The current study was focused on the anticancer activity of myristicin against MCF-7 human breast cancer (BC) cells. BC is the most common and leading malignant disease in women worldwide. Now-a-days, various conventional therapies are used against BC and still represent a chief challenge because those treatments fail to differentiate normal cells from malignant cells, and they have severe side effects also. So, there is a need develop new therapies to decrease BC-related morbidity and mortality. Myristicin, a 1‑allyl‑5‑methoxy‑3, 4‑methylenedioxybenzene, is a main active aromatic compound present in various spices, such as nutmeg, mace, carrot, cinnamon, parsely and some essential oils. Myristicin has a wide range of effects, including antitumor, antioxidative and antimicrobial activity. Nevertheless, the effects of myristicin on human BC cells remain largely unrevealed. The cytotoxicity effect of myristicin on MCF‑7 cells was increased dose dependently detected by (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Lactate Dehydrogenase assays. Myristicin was found to be significantly inducing the cell apoptosis, as compared to control, using acridine orange/ethidium bromide, Hoechst stain and annexin V. Moreover, it activates cell antimigration, intracellular reactive oxygen species generation and cell cycle arrest in the G1/S phase. In addition, myristicin induces the expression of apoptosis and cell cycle genes (Caspases8, Bax, Bid, Bcl2, PARP, p53, and Cdk1) was demonstrated by quantitative polymerase chain reaction and apoptosis proteins (c-PARP, Caspase 9, Cytochrome C, PDI) expression was also analyzed with western blot. Overall, we illustrated that myristicin could regulate apoptosis signaling pathways in MCF-7 BC cells.

Crosstalk between protein misfolding and endoplasmic reticulum stress during ageing and their role in age-related disorders

Maintaining the proteome is crucial to retaining cell functionality and response to multiple intrinsic and extrinsic stressors. Protein misfolding increased the endoplasmic reticulum (ER) stress and activated the adaptive unfolded protein response (UPR) to restore cell homeostasis. Apoptosis occurs when ER stress is prolonged or the adaptive response fails. In healthy young cells, the ratio of protein folding machinery to quantities of misfolded proteins is balanced under normal circumstances. However, the age-related deterioration of the complex systems for handling protein misfolding is accompanied by ageing-related disruption of protein homeostasis, which results in the build-up of misfolded and aggregated proteins. This ultimately results in decreased cell viability and forms the basis of common age-related diseases called protein misfolding diseases. Proteins or protein fragments convert from their ordinarily soluble forms to insoluble fibrils or plaques in many of these disorders, which build up in various organs such as the liver, brain, or spleen. Alzheimer's, Parkinson's, type II diabetes, and cancer are diseases in this group commonly manifest in later life. Thus, protein misfolding and its prevention by chaperones and different degradation paths are becoming understood from molecular perspectives. Proteodynamics information will likely affect future interventional techniques to combat cellular stress and support healthy ageing by avoiding and treating protein conformational disorders. This review provides an overview of the diverse proteostasis machinery, protein misfolding, and ER stress involvement, which activates the UPR sensors. Here, we will discuss the crosstalk between protein misfolding and ER stress and their role in developing age-related diseases.

Echinops Asteraceae extract guards against malathion-induced liver damage via minimizing oxidative stress, inflammation, and apoptosis

Malathion (MAL) is one of the highly toxic organophosphorus (OP) compounds that induces hepatotoxicity. Echinops. ritro leaves extract (ERLE) is traditionally used in the treatment of bacterial/fungal infections. This study's goal was to investigate the potential of extracts from ERLE against hepatotoxicity induced by MAL in male albino rats. Four equal groups of forty mature male albino rats were created: The rats in the first group used as a control. The second group of rats received ERLE orally. The third group received MAL. ERLE and MAL were administered to the fourth group of rats. Six-week treatment groups were conducted. Using lipid peroxidation indicators [malondialdehyde (MDA), alanine aminotransferase (ALT), aspartate aminotransferase (AST)], oxidative stress markers [catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)], apoptotic markers [Bcl-2 & caspase-3] and tumor necrosis factor alpha (TNF-α). Rats treated with MAL underwent a significant increase on MDA, ALT, AST, caspase-3 and TNF-α marker with a significant decrease in antioxidant markers [CAT, SOD, GPx] and Bcl-2. Histologically, MAL-treated group's liver sections displayed damaged hepatocytes with collapsed portions, pyknotic nuclei, vacuolated cytoplasm, and congested central veins. Ultra structurally, rat livers treated with MAL showed dilated cisternae of endoplasmic reticulum, swollen mitochondria with disrupted cristae, nuclei with disrupted chromatin content, multiple lysosomes, multiple vacuolations and a disrupted blood sinusoid. With rats treated with ERLE, these alterations were essentially non-existent. It is possible to conclude that ERLE protects against MAL hepatotoxicity, and that this protection is related, at least in part, to its antioxidant activities.

The Relationship Between Inflammatory Processes and Apoptosis in Lumbar Disc Degeneration

OBJECTIVE

Degenerative Disc Disease (DDD) is a common health problem in the population. There are recent studies focusing on relationship between DDD and immunological factors. However, there is still a lack of data on the role of apoptosis in DDD pathophysiology. Therefore, we aimed to investigate the relationship between Modic-type changes and the apoptosis in DDD.

MATERIALS AND METHODS

Ninety adult male patients who presented with low back and/or radicular pain and were operated on due to lumbar disc herniation were included. Three groups were formed based on Modic type degeneration observed on magnetic resonance imaging. Specific parameters involved in the intrinsic and extrinsic pathways of apoptosis were assessed in excised disc materials using the enzyme-linked immunosorbent assay method.

RESULTS

All three groups formed according to Modic degeneration types were homogenous in all variances. Cytochrome-C was significantly decreased only in the Modic type-3 group, whereas Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Receptor-1, B-Cell Lymphoma-2 (Bcl-2) Homologous Antagonist Killer-1, Direct Inhibitor of Apoptosis-Binding Protein with Low Pi, and Bcl-2 Associated X Apoptosis Regulator levels were significantly different in both Modic type-2 and -3 groups. However, BH3 interacting domain death agonist and Bcl-2 levels were similar across all groups.

CONCLUSIONS

In conclusion, this study suggests that Direct Inhibitor of Apoptosis-Binding Protein with Low Pi, cytochrome - c, Bcl-2 Associated X Apoptosis Regulator, Bcl-2 Homologous Antagonist Killer-1, and Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Receptor-1proteins play important roles in the development and progression of DDD and are correlated with Modic types. Further studies are needed to explore the potential therapeutic role of inhibiting these apoptotic proteins in DDD.

Visualization of scientific production in Caenorhabditis elegans: a bibliometric analysis (1980-2023)

Caenorhabditis elegans (C. elegans) is a nematode and model organism whose entire genome has been mapped, which allows for easy observation of the organism's development due to its transparent structure, and which is appealing due to its ease of crossover, ease of culture, and low cost. Despite being separated by nearly a billion years of evolution, C. elegans homologs have been identified for the vast majority of human genes and are associated with C. elegans for many biological processes such as apoptosis, cell signaling, cell cycle, cell polarity, metabolism, and aging. A detailed bibliometric study is performed here to examine publication trends in this field. Data were taken from the Web of Science database and analyzed using the bibliometric application Biblioshiny (RStudio). In terms of publication, the results indicated a gradual increase each year between 1980 and 2023. A total of 20,322 records were issued in 96 countries, the majority of which were in the USA, China, and Japan. The most prolific writers, the journals most engaged in the area, the nations, institutions, and keywords used by authors were all determined using the Web of Science database and bibliometric rules. The number of papers in the C. elegans research field is increasing exponentially, and Genetics is the journal with the highest number of articles. This study presents how research patterns have evolved throughout time. As a result, worldwide cooperation and a potential field can be developed.

Mastering Death: The Roles of Viral Bcl-2 in dsDNA Viruses

Proteins of the Bcl-2 family regulate cellular fate via multiple mechanisms including apoptosis, autophagy, senescence, metabolism, inflammation, redox homeostasis, and calcium flux. There are several regulated cell death (RCD) pathways, including apoptosis and autophagy, that use distinct molecular mechanisms to elicit the death response. However, the same proteins/genes may be deployed in multiple biochemical pathways. In apoptosis, Bcl-2 proteins control the integrity of the mitochondrial outer membrane (MOM) by regulating the formation of pores in the MOM and apoptotic cell death. A number of prosurvival genes populate the genomes of viruses including those of the pro-survival Bcl-2 family. Viral Bcl-2 proteins are sequence and structural homologs of their cellular counterparts and interact with cellular proteins in apoptotic and autophagic pathways, potentially allowing them to modulate these pathways and determine cellular fate.

A guide to cell death pathways

Regulated cell death mediated by dedicated molecular machines, known as programmed cell death, plays important roles in health and disease. Apoptosis, necroptosis and pyroptosis are three such programmed cell death modalities. The caspase family of cysteine proteases serve as key regulators of programmed cell death. During apoptosis, a cascade of caspase activation mediates signal transduction and cellular destruction, whereas pyroptosis occurs when activated caspases cleave gasdermins, which can then form pores in the plasma membrane. Necroptosis, a form of caspase-independent programmed necrosis mediated by RIPK3 and MLKL, is inhibited by caspase-8-mediated cleavage of RIPK1. Disruption of cellular homeostatic mechanisms that are essential for cell survival, such as normal ionic and redox balance and lysosomal flux, can also induce cell death without invoking programmed cell death mechanisms. Excitotoxicity, ferroptosis and lysosomal cell death are examples of such cell death modes. In this Review, we provide an overview of the major cell death mechanisms, highlighting the latest insights into their complex regulation and execution, and their relevance to human diseases.

Unlocking potential: the role of the electron transport chain in immunometabolism

The electron transport chain (ETC) couples electron transfer with proton pumping to generate ATP and it also regulates particular innate and adaptive immune cell function. While NLRP3 inflammasome activation was initially linked to reactive oxygen species (ROS) produced from Complexes I and III, recent research suggests that an intact ETC fueling ATP is needed. Complex II may be responsible for Th1 cell proliferation and in some cases, effector cytokine production. Complex III is required for regulatory T (Treg) cell function, while oxidative phosphorylation (OXPHOS) and Complexes I, IV, and V sustain proliferation and antibody production in B lymphocytes, with OXPHOS also being required for B regulatory (Breg) cell function. Despite challenges, the ETC shows therapeutic targeting potential for immune-related diseases and in immuno-oncology.

NcRNAs: A synergistically antiapoptosis therapeutic tool in Alzheimer's disease

AIMS

The aim of this review is to systematically summarize and analyze the noncoding RNAs (ncRNAs), especially microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), in the cell apoptosis among Alzheimer's disease (AD) in recent years to demonstrate their value in the diagnosis and treatment of AD.

METHODS

We systematically summarized in vitro and in vivo studies focusing on the ncRNAs in the regulation of cell apoptosis among AD in PubMed, ScienceDirect, and Google Scholar.

RESULTS

We discover three patterns of ncRNAs (including 'miRNA-mRNA', 'lncRNA-miRNA-mRNA', and 'circRNA-miRNA-mRNA') form the ncRNA-based regulatory networks in regulating cell apoptosis in AD.

CONCLUSIONS

This review provides a future diagnosis and treatment strategy for AD patients based on ncRNAs.

Diverse functions of cytochrome c in cell death and disease

The redox-active protein cytochrome c is a highly positively charged hemoglobin that regulates cell fate decisions of life and death. Under normal physiological conditions, cytochrome c is localized in the mitochondrial intermembrane space, and its distribution can extend to the cytosol, nucleus, and extracellular space under specific pathological or stress-induced conditions. In the mitochondria, cytochrome c acts as an electron carrier in the electron transport chain, facilitating adenosine triphosphate synthesis, regulating cardiolipin peroxidation, and influencing reactive oxygen species dynamics. Upon cellular stress, it can be released into the cytosol, where it interacts with apoptotic peptidase activator 1 (APAF1) to form the apoptosome, initiating caspase-dependent apoptotic cell death. Additionally, following exposure to pro-apoptotic compounds, cytochrome c contributes to the survival of drug-tolerant persister cells. When translocated to the nucleus, it can induce chromatin condensation and disrupt nucleosome assembly. Upon its release into the extracellular space, cytochrome c may act as an immune mediator during cell death processes, highlighting its multifaceted role in cellular biology. In this review, we explore the diverse structural and functional aspects of cytochrome c in physiological and pathological responses. We summarize how posttranslational modifications of cytochrome c (e.g., phosphorylation, acetylation, tyrosine nitration, and oxidation), binding proteins (e.g., HIGD1A, CHCHD2, ITPR1, and nucleophosmin), and mutations (e.g., G41S, Y48H, and A51V) affect its function. Furthermore, we provide an overview of the latest advanced technologies utilized for detecting cytochrome c, along with potential therapeutic approaches related to this protein. These strategies hold tremendous promise in personalized health care, presenting opportunities for targeted interventions in a wide range of conditions, including neurodegenerative disorders, cardiovascular diseases, and cancer.

Different concentrations of betaxolol switch cell fate between necroptosis, apoptosis, and senescence in human corneal stromal cells

Betaxolol is commonly used to manage glaucoma in clinical practice. However, its long-term use may damage the cornea. Thus, the cytotoxicity and mechanisms of betaxolol in human corneal stromal cells (HCSCs) warrant further study. In this study, we used in vitro HCSCs and in vivo rabbit corneal models to investigate betaxolol cytotoxic effects and mechanism of action. At near-clinical concentrations (0.28% and 0.14%), betaxolol inhibited caspase-8 activity, activated receptor-interacting protein kinase (RIPK)1, RIPK3, and mixed-spectrum kinase-like domain (MLKL), and phosphorylated MLKL to induce necroptosis in HCSCs. Similarly, moderate concentrations of betaxolol (0.07%-0.0175%) activated caspase-8 to trigger the exogenous apoptotic pathway. Through the intrinsic apoptotic pathway, betaxolol upregulated the expression of Bcl-2 family apoptotic proteins Bax and Bad and downregulated that of anti-apoptotic proteins Bcl-2 and Bcl-xL. This subsequently disrupted the mitochondrial membrane potential and cytoplasmic transfer of cytochrome c and apoptosis-inducing factor, activated caspase-9, and induced apoptosis in HCSCs. Furthermore, continuous treatment with low betaxolol concentrations (0.00875%) for three generations of HCSCs prevented apoptosis by promoting the expression of Bcl-xL and suppressing that of Bax. However, its toxic effects initiated cellular senescence by increasing reactive oxygen species, leading to the disruption of energy metabolism and DNA damage. Finally, clinical concentrations of betaxolol had a pro-apoptotic effect on rabbit corneal stromal cells in vivo. These results suggest that betaxolol induces cytotoxicity in a concentration-dependent manner in HCSCs, and that caspase-8 and Bcl-2 family proteins may be critical switches in the conversion of different HCSC death mechanisms.

A comparative study of apoptosis, pyroptosis, necroptosis, and PANoptosis components in mouse and human cells

Regulated cell death is a key component of the innate immune response, which provides the first line of defense against infection and homeostatic perturbations. However, cell death can also drive pathogenesis. The most well-defined cell death pathways can be categorized as nonlytic (apoptosis) and lytic (pyroptosis, necroptosis, and PANoptosis). While specific triggers are known to induce each of these cell death pathways, it is unclear whether all cell types express the cell death proteins required to activate these pathways. Here, we assessed the protein expression and compared the responses of immune and non-immune cells of human and mouse origin to canonical pyroptotic (LPS plus ATP), apoptotic (staurosporine), necroptotic (TNF-α plus z-VAD), and PANoptotic (influenza A virus infection) stimuli. When compared to fibroblasts, both mouse and human innate immune cells, macrophages, expressed higher levels of cell death proteins and activated cell death effectors more robustly, including caspase-1, gasdermins, caspase-8, and RIPKs, in response to specific stimuli. Our findings highlight the importance of considering the cell type when examining the mechanisms regulating inflammation and cell death. Improved understanding of the cell types that contain the machinery to execute different forms of cell death and their link to innate immune responses is critical to identify new strategies to target these pathways in specific cellular populations for the treatment of infectious diseases, inflammatory disorders, and cancer.

Dark and Dronc activation in Drosophila melanogaster

The onset of apoptosis is characterized by a cascade of caspase activation, where initiator caspases are activated by a multimeric adaptor complex known as the apoptosome. In Drosophila melanogaster, the initiator caspase Dronc undergoes autocatalytic activation in the presence of the Dark apoptosome. Despite rigorous investigations, the activation mechanism for Dronc remains elusive. Here, we report the cryo-EM structures of an auto-inhibited Dark monomer and a single-layered, multimeric Dark/Dronc complex. Our biochemical analysis suggests that the auto-inhibited Dark oligomerizes upon binding to Dronc, which is sufficient for the activation of both Dark and Dronc. In contrast, the previously observed double-ring Dark apoptosome may represent a non-functional or "off-pathway" conformation. These findings expand our understanding on the molecular mechanism of apoptosis in Drosophila.

Proposed mechanisms of tau: relationships to traumatic brain injury, Alzheimer's disease, and epilepsy

Traumatic brain injury (TBI), Alzheimer's disease (AD), and epilepsy share proposed mechanisms of injury, including neuronal excitotoxicity, cascade signaling, and activation of protein biomarkers such as tau. Although tau is typically present intracellularly, in tauopathies, phosphorylated (p-) and hyper-phosphorylated (hp-) tau are released extracellularly, the latter leading to decreased neuronal stability and neurofibrillary tangles (NFTs). Tau cleavage at particular sites increases susceptibility to hyper-phosphorylation, NFT formation, and eventual cell death. The relationship between tau and inflammation, however, is unknown. In this review, we present evidence for an imbalanced endoplasmic reticulum (ER) stress response and inflammatory signaling pathways resulting in atypical p-tau, hp-tau and NFT formation. Further, we propose tau as a biomarker for neuronal injury severity in TBI, AD, and epilepsy. We present a hypothesis of tau phosphorylation as an initial acute neuroprotective response to seizures/TBI. However, if the underlying seizure pathology or TBI recurrence is not effectively treated, and the pathway becomes chronically activated, we propose a "tipping point" hypothesis that identifies a transition of tau phosphorylation from neuroprotective to injurious. We outline the role of amyloid beta (Aβ) as a "last ditch effort" to revert the cell to programmed death signaling, that, when fails, transitions the mechanism from injurious to neurodegenerative. Lastly, we discuss targets along these pathways for therapeutic intervention in AD, TBI, and epilepsy.

Cell death in cancer chemotherapy using taxanes

Cancer cells evolve to be refractory to the intrinsic programmed cell death mechanisms, which ensure cellular tissue homeostasis in physiological conditions. Chemotherapy using cytotoxic drugs seeks to eliminate cancer cells but spare non-cancerous host cells by exploring a likely subtle difference between malignant and benign cells. Presumably, chemotherapy agents achieve efficacy by triggering programmed cell death machineries in cancer cells. Currently, many major solid tumors are treated with chemotherapy composed of a combination of platinum agents and taxanes. Platinum agents, largely cis-platin, carboplatin, and oxaliplatin, are DNA damaging agents that covalently form DNA addicts, triggering DNA repair response pathways. Taxanes, including paclitaxel, docetaxel, and cabazitaxel, are microtubule stabilizing drugs which are often very effective in purging cancer cells in clinical settings. Generally, it is thought that the stabilization of microtubules by taxanes leads to mitotic arrest, mitotic catastrophe, and the triggering of apoptotic programmed cell death. However, the precise mechanism(s) of how mitotic arrest and catastrophe activate the caspase pathway has not been established. Here, we briefly review literature on the involvement of potential cell death mechanisms in cancer therapy. These include the classical caspase-mediated apoptotic programmed cell death, necroptosis mediated by MLKL, and pore forming mechanisms in immune cells, etc. In particular, we discuss a newly recognized mechanism of cell death in taxane-treatment of cancer cells that involves micronucleation and the irreversible rupture of the nuclear membrane. Since cancer cells are commonly retarded in responding to programmed cell death signaling, stabilized microtubule bundle-induced micronucleation and nuclear membrane rupture, rather than triggering apoptosis, may be a key mechanism accounting for the success of taxanes as anti-cancer agents.

Wireless electrical-molecular quantum signalling for cancer cell apoptosis

Quantum biological tunnelling for electron transfer is involved in controlling essential functions for life such as cellular respiration and homoeostasis. Understanding and controlling the quantum effects in biology has the potential to modulate biological functions. Here we merge wireless nano-electrochemical tools with cancer cells for control over electron transfer to trigger cancer cell death. Gold bipolar nanoelectrodes functionalized with redox-active cytochrome c and a redox mediator zinc porphyrin are developed as electric-field-stimulating bio-actuators, termed bio-nanoantennae. We show that a remote electrical input regulates electron transport between these redox molecules, which results in quantum biological tunnelling for electron transfer to trigger apoptosis in patient-derived cancer cells in a selective manner. Transcriptomics data show that the electric-field-induced bio-nanoantenna targets the cancer cells in a unique manner, representing electrically induced control of molecular signalling. The work shows the potential of quantum-based medical diagnostics and treatments.

Aspergillus fumigatus cytochrome c impacts conidial survival during sterilizing immunity

IMPORTANCE

Aspergillus fumigatus can cause a life-threatening infection known as invasive pulmonary aspergillosis (IPA), which is marked by fungus-attributable mortality rates of 20%-30%. Individuals at risk for IPA harbor genetic mutations or incur pharmacologic defects that impair myeloid cell numbers and/or function, exemplified by bone marrow transplant recipients, patients that receive corticosteroid therapy, or patients with chronic granulomatous disease (CGD). However, treatments for Aspergillus infections remain limited, and resistance to the few existing drug classes is emerging. Recently, the World Health Organization classified A. fumigatus as a critical priority fungal pathogen. Our cell death research identifies an important aspect of fungal biology that impacts susceptibility to leukocyte killing. Furthering our understanding of mechanisms that mediate the outcome of fungal-leukocyte interactions will increase our understanding of both the underlying fungal biology governing cell death and innate immune evasion strategies utilized during mammalian infection pathogenesis. Consequently, our studies are a critical step toward leveraging these mechanisms for novel therapeutic advances.

Activation of caspase-9 on the apoptosome as studied by methyl-TROSY NMR

Mitochondrial apoptotic signaling cascades lead to the formation of the apoptosome, a 1.1-MDa heptameric protein scaffold that recruits and activates the caspase-9 protease. Once activated, caspase-9 cleaves and activates downstream effector caspases, triggering the onset of cell death through caspase-mediated proteolysis of cellular proteins. Failure to activate caspase-9 enables the evasion of programmed cell death, which occurs in various forms of cancer. Despite the critical apoptotic function of caspase-9, the structural mechanism by which it is activated on the apoptosome has remained elusive. Here, we used a combination of methyl-transverse relaxation-optimized NMR spectroscopy, protein engineering, and biochemical assays to study the activation of caspase-9 bound to the apoptosome. In the absence of peptide substrate, we observed that both caspase-9 and its isolated protease domain (PD) only very weakly dimerize with dissociation constants in the millimolar range. Methyl-NMR spectra of isotope-labeled caspase-9, within the 1.3-MDa native apoptosome complex or an engineered 480-kDa apoptosome mimic, reveal that the caspase-9 PD remains monomeric after recruitment to the scaffold. Binding to the apoptosome, therefore, organizes caspase-9 PDs so that they can rapidly and extensively dimerize only when substrate is present, providing an important layer in the regulation of caspase-9 activation. Our work highlights the unique role of NMR spectroscopy to structurally characterize protein domains that are flexibly tethered to large scaffolds, even in cases where the molecular targets are in excess of 1 MDa, as in the present example.

Hesperidin Methyl Chalcone reduces extracellular Aβ(25-35) peptide aggregation and fibrillation and also protects Neuro 2a cells from Aβ(25-35) induced neuronal dysfunction

In the present study, we evaluated the neuroprotective potential of Hesperidin Methyl Chalcone (HMC) against the neurotoxicity induced by Aβ(25-35) peptide. HMC demonstrated higher free-radical scavenging activity than Hesperidin in initial cell-free studies. Investigations using the fluorescent dye thioflavin T with Aβ(25-35) peptide showed that HMC has the ability to combat extracellular amyloid aggregation by possessing anti-aggregation property against oligomers and by disaggregating mature fibrils. Also, the results of the molecular simulation studies show that HMC ameliorated oligomer formation. Further, the anti-Alzheimer's property of HMC was investigated in in vitro cell conditions by pre-treating the neuro 2a (N2a) cells with HMC before inducing Aβ(25-35) toxicity. The findings demonstrate that HMC increased cell viability, reduced oxidative stress, prevented macromolecular damage, allayed mitochondrial dysfunction, and exhibited anticholinesterase activity. HMC also reduced Aβ induced neuronal cell death by modulating caspase-3 activity, Bax expression and Bcl2 overexpression, demonstrating that HMC pre-treatment reduced mitochondrial damage and intrinsic apoptosis induced by Aβ(25-35).In silico evaluation against potential AD targets reveal that HMC could be a potent inhibitor of BACE-1, inhibiting the formation of toxic Aβ peptides. Overall, the findings imply that the neuroprotective efficacy of HMC has high prospects for addressing a variety of pathogenic consequences caused by amyloid beta in AD situations and alleviating cognitive impairments.

Pathogen-driven nucleotide overload triggers mitochondria-centered cell death in phagocytes

Staphylococcus aureus is a dangerous pathogen that evolved refined immuno-evasive strategies to antagonize host immune responses. This involves the biogenesis of death-effector deoxyribonucleosides, which kill infectious foci-penetrating macrophages. However, the exact mechanisms whereby staphylococcal death-effector deoxyribonucleosides and coupled imbalances of intracellular deoxyribonucleotide species provoke immune cell death remain elusive. Here, we report that S. aureus systematically promotes an overload of deoxyribonucleotides to trigger mitochondrial rupture in macrophages, a fatal event that induces assembly of the caspase-9-processing apoptosome and subsequent activation of the intrinsic pathway of apoptosis. Remarkably, genetic disruption of this cascade not only helps macrophages coping with death-effector deoxyribonucleoside-mediated cytotoxicity but also enhances their infiltration into abscesses thereby ameliorating pathogen control and infectious disease outcomes in laboratory animals. Combined with the discovery of protective alleles in human CASP9, these data highlight the role of mitochondria-centered apoptosis during S. aureus infection and suggest that gene polymorphisms may shape human susceptibility toward a predominant pathogen.

Phellinus merrillii extracts induce apoptosis of vascular smooth muscle cells via intrinsic and extrinsic pathways

Restenosis frequently occurs after balloon angioplasty. Percutaneous coronary intervention (PCI)-induced artery damage is a significant part of triggering restenosis of the vascular smooth muscles (VSMC). This study aimed to study how ethanol extract of Phellinus merrillii (EPM) affected balloon injury-induced overgrowth of VSMC, indicating neointima formation. Firstly, our results demonstrated that EPM notably decreased VSMC viability. A fragmentation assay and Annexin V/Propidium Iodide apoptosis assay showed that higher doses of EPM significantly induced the apoptosis of VSMC after 24 h of exposure. Total protein extracted from VSMC treated with EPM in various time and concentration periods was then conducted in Western blotting analysis. Our data demonstrated that EPM substantially elevated the p53, p21, Fas, Bax, p-p38, and active caspase-3 protein expressions. The results indicated that EPM induces VSMC apoptosis via intrinsic and extrinsic pathways. Also, our results demonstrated that EPM effectively attenuated the balloon injury-induced neointima formation. In conclusion, the information offers a mechanism of EPM in inducing the VSMC apoptosis, thus as a potential interference for restenosis.

Triptolide induces PANoptosis in macrophages and causes organ injury in mice

Macrophages represent the first lines of innate defense against pathogenic infections and are poised to undergo multiple forms of regulated cell death (RCD) upon infections or toxic stimuli, leading to multiple organ injury. Triptolide, an active compound isolated from Tripterygium wilfordii Hook F., possesses various pharmacological activities including anti-tumor and anti-inflammatory effects, but its applications have been hampered by toxic adverse effects. It remains unknown whether and how triptolide induces different forms of RCD in macrophages. In this study, we showed that triptolide exhibited significant cytotoxicity on cultured macrophages in vitro, which was associated with multiple forms of lytic cell death that could not be fully suppressed by any one specific inhibitor for a single form of RCD. Consistently, triptolide induced the simultaneous activation of pyroptotic, apoptotic and necroptotic hallmarks, which was accompanied by the co-localization of ASC specks respectively with RIPK3 or caspase-8 as well as their interaction with each other, indicating the formation of PANoptosome and thus the induction of PANoptosis. Triptolide-induced PANoptosis was associated with mitochondrial dysfunction and ROS production. PANoptosis was also induced by triptolide in mouse peritoneal macrophages in vivo. Furthermore, triptolide caused kidney and liver injury, which was associated with systemic inflammatory responses and the activation of hallmarks for PANoptosis in vivo. Collectively, our data reveal that triptolide induces PANoptosis in macrophages in vitro and exhibits nephrotoxicity and hepatotoxicity associated with induction of PANoptosis in vivo, suggesting a new avenue to alleviate triptolide's toxicity by harnessing PANoptosis.

PANoptosis in cancer, the triangle of cell death

BACKGROUND

PANoptosis is a novel form of programmed cell death (PCD) found in 2019 that is regulated by the PANoptosome. PANoptosis combines essential features of pyroptosis, apoptosis, and necroptosis, forming a "death triangle" of cells. While apoptosis, pyroptosis, and necroptosis have been extensively studied for their roles in human inflammatory diseases and many other clinical conditions, historically they were considered as independent processes. However, emerging evidence indicates that these PCDs exhibit cross talk and interactions, resulting in the development of the concept of PANoptosis.

METHODS

In this review, we offer a concise summary of the fundamental mechanisms of apoptosis, pyroptosis, and necroptosis. We subsequently introduce the notion of PANoptosis and detail the assembly mechanism of the PANoptosome complex which is responsible for inducing cell death. We also describe some regulatory networks of PANoptosis.

RESULTS

PANoptosis now has been associated with various human diseases including cancer. Although the exact function of PANoptosis in each tumor is not fully understood, it represents a prospective avenue for cancer therapy, offering promise for advancements in cancer therapy.

CONCLUSIONS

In the future, in-depth study of PANoptosis will continue to help us in understanding the fundamental processes underlying cell death and provide scientific support for cancer research.

Vitamin E-Inhibited Phoxim-Induced Renal Oxidative Stress and Mitochondrial Apoptosis In Vivo and In Vitro of Piglets

Exposure to phoxim at low levels caused bioaccumulation with neurotoxicity but also induced oxidative stress, tissue damage, and abnormal nutrient metabolism. This study described that vitamin E ameliorates phoxim-induced nephrotoxicity via inhibiting mitochondrial apoptosis. In vivo, 24 healthy piglets were treated with phoxim (0 mg/kg and 500 mg/kg) and vitamin E + phoxim (vitamin E + phoxim: 200 mg/kg + 500 mg/kg). In vitro, PK15 cells were treated with phoxim (0 mg/L and 1 mg/L) and vitamin E + phoxim (phoxim + vitamin E: 1 mg/L + 1 mg/L) for 12 h and 24 h. Our results indicated that accumulation of ROS, oxidative stress, and renal cell injury through stimulation of mitochondrial apoptosis resulted in phoxim-induced nephrotoxicity. Phoxim resulted in swollen mitochondria, blurred internal cristae, renal glomerular atrophy, and renal interstitial fibrosis. Vitamin E alleviated the adverse effects of phoxim by reducing ROS and improving antioxidant capacity in vivo and in vitro. Vitamin E significantly increased SDH in vitro (p < 0.01), while it decreased ROS, Bad, and cyto-c in vitro and SOD and CAT in vivo (p < 0.05). Vitamin E ameliorated phoxim-induced renal histopathologic changes, and mitochondria swelled. In addition, vitamin E regulates phoxim-induced apoptosis by alleviating oxidative damage to the mitochondria.

New Steroidal Selenides as Proapoptotic Factors

Cytostatic and pro-apoptotic effects of selenium steroid derivatives against HeLa cells were determined. The highest cytostatic activity was shown by derivative 4 (GI50 25.0 µM, almost complete growth inhibition after three days of culture, and over 97% of apoptotic and dead cells at 200 µM). The results of our study (cell number measurements, apoptosis profile, relative expression of apoptosis-related APAF1, BID, and mevalonate pathway-involved HMGCR, SQLE, CYP51A1, and PDHB genes, and computational chemistry data) support the hypothesis that tested selenosteroids induce the extrinsic pathway of apoptosis by affecting the cell membrane as cholesterol antimetabolites. An additional mechanism of action is possible through a direct action of derivative 4 to inhibit PDHB expression in a way similar to steroid hormones.