Pathogen hijacks programmed cell death signaling by arginine ADPR-deacylization of caspases

Bisphenol a Disrupts Steroidogenesis and Induces Apoptosis in Human Granulosa Cells Cultured In Vitro

Bisphenol A (BPA) is a common synthetic chemical compound classified as an endocrine disruptor. It affects multiple physiological systems in the body, including the female reproductive system, particularly granulosa cells (GCs) in the ovaries, where steroidogenesis occurs. This study investigated the impact of various BPA concentrations (environmentally relevant concentrations of 0.001 µM and 0.1 µM and toxicological concentration of 100 µM) and exposure times (24 and 72 h) on cell viability and counts and in vitro production of estradiol and progesterone in human GCs collected from waste follicular fluid of IVF patients. Gene expression analysis of 182 genes associated with steroidogenesis and apoptosis was performed in GCs using PCR arrays, followed by protein expression analysis by Western blot. Our results demonstrate that after longer BPA exposure (72 h), a higher concentration of BPA (100 µM) negatively affects the cellular viability and counts and significantly alters steroid hormone biosynthesis in vitro, leading to reduced concentrations of estradiol and progesterone in the culture medium. We found that all BPA concentrations altered the expression of different steroidogenesis- and apoptosis-related genes in GCs. At 0.001 μM, BPA exposure decreased the expression of TRIM25, UGT2B15, CASP3, and RPS6KA3 genes and increased the expression of NR6A1 and PPID genes. At 0.1 μM, BPA increased the expression of AR, HSD3B1, BID, IKBKG, and PPID genes while reducing the expression of TRIM25 and CASP3 genes. At the highest concentration of 100 μM, BPA upregulated the expression of AR, GPER30, BID, IKBKG, and PPID genes and downregulated the expression of FOXO1 and UGT2B15 genes. These results highlight BPA's concentration-specific effects on steroidogenesis and apoptosis and show its potential to compromise GC function, with possible negative implications for female fertility and ovarian health, even at environmentally relevant concentrations.

Pathogen effectors hijack calcium signaling to promote virulence

Calcium signaling is a cornerstone of plant defense responses. In this opinion article we explore how pathogens exploit this pathway by targeting calcium sensors such as calmodulin (CaM) and calmodulin-like proteins (CMLs) with their secreted effectors. We illustrate different mechanisms by which effectors manipulate calcium homeostasis, cytoskeletal dynamics, metabolism, hormone biosynthesis, gene regulation, and chloroplast function to suppress plant immunity and enhance virulence. Targeting calcium signaling to thwart or weaken host defenses appears to be a common strategy among pathogens infecting animal cells, and we present here selected examples of this convergence. Understanding these strategies provides valuable insights into the interactions between plants and pathogens, and should pave the way for the development of new disease control strategies.

An integrative analysis reveals cancer risk associated with artificial sweeteners

BACKGROUND

Artificial sweeteners (AS) have been widely utilized in the food, beverage, and pharmaceutical industries for decades. While numerous publications have suggested a potential link between AS and diseases, particularly cancer, controversy still surrounds this issue. This study aims to investigate the association between AS consumption and cancer risk.

METHODS

Targets associated with commonly used AS were screened and validated using databases such as CTD, STITCH, Super-PRED, Swiss Target Prediction, SEA, PharmMapper, and GalaxySagittarius. Cancer-related targets were sourced from GeneCards, OMIM, and TTD databases. AS-cancer targets were identified through the intersection of these datasets. A network visualization ('AS-targets-cancer') was constructed using Cytoscape 3.9.0. Protein-protein interaction analysis was conducted using the STRING database to identify significant AS-cancer targets. GO and KEGG enrichment analyses were performed using the DAVID database. Core targets were identified from significant targets and genes involved in the 'Pathways in cancer' (map05200). Molecular docking and dynamics simulations were employed to verify interactions between AS and target proteins. Pan-cancer and univariate Cox regression analyses of core targets across 33 cancer types were conducted using GEPIA 2 and SangerBox, respectively. Gene chip datasets (GSE53757 for KIRC, GSE21354 for LGG, GSE42568 for BRCA, and GSE46602 for PRAD) were retrieved from the GEO database, while transcriptome and overall survival data were obtained from TCGA. Data normalization and identification of differentially expressed genes (DEGs) were performed on these datasets using R (version 4.3.2). Gene Set Enrichment Analysis (GSEA) was employed to identify critical pathways in the gene expression profiles between normal and cancer groups. A cancer risk prognostic model was constructed for key targets to further elucidate their significance in cancer initiation and progression. Finally, the HPA database was utilized to investigate variations in the expression of key AS-cancer target proteins across KIRC, LGG, BRCA, PRAD, and normal tissues.

RESULTS

Seven commonly used AS (Aspartame, Acesulfame, Sucralose, NHDC, Cyclamate, Neotame, and Saccharin) were selected for study. A total of 368 AS-cancer intersection targets were identified, with 48 notable AS-cancer targets, including TP53, EGFR, SRC, PIK3R1, and EP300, retrieved. GO biological process analysis indicated that these targets are involved in the regulation of apoptosis, gene expression, and cell proliferation. Thirty-five core targets were identified from the intersection of the 48 significant AS-cancer targets and genes in the 'Pathways in cancer' (map05200). KEGG enrichment analysis of these core targets revealed associations with several cancer types and the PI3K-Akt signaling pathway. Molecular docking and dynamics simulations confirmed interactions between AS and these core targets. HSP90AA1 was found to be highly expressed across the 33 cancer types, while EGF showed the opposite trend. Univariate Cox regression analysis demonstrated strong associations of core targets with KIRC, LGG, BRCA, and PRAD. DEGs of AS-cancer core targets across these four cancers were analyzed. GSEA revealed upregulated and downregulated pathways enriched in KIRC, LGG, BRCA, and PRAD. Cancer risk prognostic models were constructed to elucidate the significant roles of key targets in cancer initiation and progression. Finally, the HPA database confirmed the crucial function of these targets in KIRC, LGG, BRCA, and PRAD.

CONCLUSION

This study integrated data mining, machine learning, network toxicology, molecular docking, molecular dynamics simulations, and clinical sample analysis to demonstrate that AS increases the risk of kidney cancer, low-grade glioma, breast cancer, and prostate cancer through multiple targets and signaling pathways. This paper provides a valuable reference for the safety assessment and cancer risk evaluation of food additives. It urges food safety regulatory agencies to strengthen oversight and encourages the public to reduce consumption of foods and beverages containing artificial sweeteners and other additives.

Insights into mechanisms of ubiquitin ADP-ribosylation reversal

Ubiquitination and ADP-ribosylation are two types of post-translational modification (PTM) involved in regulating various cellular activities. In a striking example of direct interplay between ubiquitination and ADP-ribosylation, the bacterial pathogen Legionella pneumophila uses its SidE family of secreted effectors to catalyze an NAD+-dependent phosphoribosyl ubiquitination of host substrates in a process involving the intermediary formation of ADP-ribosylated ubiquitin (ADPR-Ub). This noncanonical ubiquitination pathway is finely regulated by multiple Legionella effectors to ensure a balanced host subjugation. Among the various regulatory effectors, the macrodomain effector MavL has been recently shown to reverse the Ub ADP-ribosylation and regenerate intact Ub. Here, we briefly outline emerging knowledge on ubiquitination and ADP-ribosylation and tap into cases of direct cross-talk between these two PTMs. The chemistry of ADP-ribose in the context of the PTM and the reversal mechanisms of ADP-ribosylation are then highlighted. Lastly, focusing on recent structural studies on the MavL-mediated reversal of Ub ADP-ribosylation, we strive to deduce distinct mechanisms regarding the catalysis and product release of this reaction.

An Emerging Way for Bacteria to Engage with Host Cells via Protein ADP-riboxanation

Post-translational modifications (PTMs) are increasingly recognized as important strategies used by bacterial pathogens to modulate host cellular functions. Protein ADP-riboxanation, a derivative of ADP-ribosylation, has recently emerged as a new biochemical way by which bacterial pathogens interact with host cells. Recent studies have revealed that this modification has broad regulatory roles in host processes including cell death, protein translation, and stress granule formation. Given that the vast majority of bacterial ADP-riboxanases are still uncharacterized, in this review we also highlight the utility of advanced proteomic tools in the functional dissection of ADP-riboxanation events during bacterial infections.

The regulation of pyroptosis by post-translational modifications: molecular mechanisms and therapeutic targets

Pyroptosis, a type of programmed cell death mediated by gasdermin family proteins, releases a large amount of immune stimulatory substances, which further contribute to inflammation and elicit an adaptive immune response against tumours and pathogens. And it occurs through multiple pathways that involve the activation of specific caspases and the cleavage of gasdermins. Post-translational modifications (PTMs) could influence the chemical properties of the modified residues and neighbouring regions, ultimately affecting the activity, stability, and functions of proteins to regulate pyroptosis. Many studies have been conducted to explore the influence of PTMs on the regulation of pyroptosis. In this review, we provide a comprehensive summary of different types of PTMs that influence pyroptosis, along with their corresponding modifying enzymes. Moreover, it elaborates on the specific contributions of different PTMs to pyroptosis and delves into how the regulation of these modifications can be leveraged for therapeutic interventions in cancer and inflammatory diseases.

DNA methylation activates retron Ec86 filaments for antiphage defense

Retrons are a class of multigene antiphage defense systems typically consisting of a retron reverse transcriptase, a non-coding RNA, and a cognate effector. Although triggers for several retron systems have been discovered recently, the complete mechanism by which these systems detect invading phages and mediate defense remains unclear. Here, we focus on the retron Ec86 defense system, elucidating its modes of activation and mechanisms of action. We identified a phage-encoded DNA cytosine methyltransferase (Dcm) as a trigger of the Ec86 system and demonstrated that Ec86 is activated upon multicopy single-stranded DNA (msDNA) methylation. We further elucidated the structure of a tripartite retron Ec86-effector filament assembly that is primed for activation by Dcm and capable of hydrolyzing nicotinamide adenine dinucleotide (NAD+). These findings provide insights into the retron Ec86 defense mechanism and underscore an emerging theme of antiphage defense through supramolecular complex assemblies.

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.

Unveiling the hidden dangers: a review of non-apoptotic programmed cell death in anesthetic-induced developmental neurotoxicity

Anesthetic-induced developmental neurotoxicity (AIDN) can arise due to various factors, among which aberrant nerve cell death is a prominent risk factor. Animal studies have reported that repeated or prolonged anesthetic exposure can cause significant neuroapoptosis in the developing brain. Lately, non-apoptotic programmed cell deaths (PCDs), characterized by inflammation and oxidative stress, have gained increasing attention. Substantial evidence suggests that non-apoptotic PCDs are essential for neuronal cell death in AIDN compared to apoptosis. This article examines relevant publications in the PubMed database until April 2024. Only original articles in English that investigated the potential manifestations of non-apoptotic PCD in AIDN were analysed. Specifically, it investigates necroptosis, pyroptosis, ferroptosis, and parthanatos, elucidating the signaling mechanisms associated with each form. Furthermore, this study explores the potential relevance of these non-apoptotic PCDs pathways to the pathological mechanisms underlying AIDN, drawing upon their distinctive characteristics. Despite the considerable challenges involved in translating fundamental scientific knowledge into clinical therapeutic interventions, this comprehensive review offers a theoretical foundation for developing innovative preventive and treatment strategies targeting non-apoptotic PCDs in the context of AIDN.

Circulating inflammatory factors and risk causality associated with type 2 diabetic nephropathy: A Mendelian randomization and bioinformatics study

The main causative factors of diabetic nephropathy (DN), a common complication of diabetes mellitus, are metabolic abnormalities and hemodynamic changes. However, studies have shown that the immune-inflammatory response also plays an important role in DN pathogenesis. Therefore, in this study, we analyzed the causal relationship and immune infiltration between inflammatory factors and DN using Mendelian randomization (MR) and bioinformatics techniques. We analyzed the causal relationship between 91 inflammatory factors and DN using two-sample MR dominated by the results of inverse variance-weighted analysis. Based on the MR analysis, the immune mechanism of inflammatory factors in DN was further explored using immune cell infiltration analysis. MR analysis indicated a positive causal relationship between DN and IL1A, caspase 8 (CASP8), macrophage colony-stimulating factor 1, IL10, STAM-binding protein, and tumor necrosis factor ligand superfamily member 12 (TNFSF12) and a negative causal relationship between DN and cystatin D, fibroblast growth factor 19, neurturin, and TNFSF14. The pathogenic mechanism of CASP8 may involve the recruitment of CD4+ T cells and macrophages for DN infiltration. In this study, we found a causal relationship between DN and IL1A, CASP8, macrophage colony-stimulating factor 1, IL10, STAM-binding protein, TNFSF12, cystatin D, fibroblast growth factor 19, neurturin, and TNFSF14. Bioinformatic immune infiltration analysis further revealed that CASP8 regulates DN by influencing the infiltration of immune cells, such as T cells and macrophages.

Critical bloodstream infection caused by Chromobacterium violaceum: a case report in a 15-year-old male with sepsis-induced cardiogenic shock and purpura fulminans

Chromobacterium violaceum (C. violaceum) is a gram-negative bacillus that is widespread in tropical and subtropical areas. Although C. violaceum rarely infects humans, it can cause critical illness with a mortality rate above 50%. Here, we report the successful treatment of a 15-year-old male who presented with bloodstream infection of C. violaceum along with sepsis, specific skin lesions, and liver abscesses. Cardiogenic shock induced by sepsis was reversed by venoarterial extracorporeal membrane oxygenation (VA ECMO). Moreover, C. violaceum-related purpura fulminans, which is reported herein for the first time, was ameliorated after treatment. This case report demonstrates the virulence of C. violaceum with the aim of raising clinical awareness of this disease.

Shigella induces stress granule formation by ADP-riboxanation of the eIF3 complex

Under stress conditions, translationally stalled mRNA and associated proteins undergo liquid-liquid phase separation and condense into cytoplasmic foci called stress granules (SGs). Many viruses hijack SGs for their pathogenesis; however, whether pathogenic bacteria also exploit this pathway remains unknown. Here, we report that members of the OspC family of Shigella flexneri induce SG formation in infected cells. Mechanistically, the OspC effectors target multiple subunits of the host translation initiation factor 3 complex by ADP-riboxanation. The modification of eIF3 leads to translational arrest and thus the formation of SGs. Furthermore, OspC-mediated SGs are beneficial for S. flexneri replication within infected host cells, and bacterial strains unable to induce SGs are attenuated for virulence in a murine model of infection. Our findings reveal a mechanism by which bacterial pathogens induce SG assembly by inactivating host translational machinery and promote bacterial proliferation in host cells.

ADP-ribosylation: An emerging direction for disease treatment

ADP-ribosylation (ADPr) is a dynamically reversible post-translational modification (PTM) driven primarily by ADP-ribosyltransferases (ADPRTs or ARTs), which have ADP-ribosyl transfer activity. ADPr modification is involved in signaling pathways, DNA damage repair, metabolism, immunity, and inflammation. In recent years, several studies have revealed that new targets or treatments for tumors, cardiovascular diseases, neuromuscular diseases and infectious diseases can be explored by regulating ADPr. Here, we review the recent research progress on ART-mediated ADP-ribosylation and the latest findings in the diagnosis and treatment of related diseases.

An innate granuloma eradicates an environmental pathogen using Gsdmd and Nos2

Granulomas often form around pathogens that cause chronic infections. Here, we discover an innate granuloma model in mice with an environmental bacterium called Chromobacterium violaceum. Granuloma formation not only successfully walls off, but also clears, the infection. The infected lesion can arise from a single bacterium that replicates despite the presence of a neutrophil swarm. Bacterial replication ceases when macrophages organize around the infection and form a granuloma. This granuloma response is accomplished independently of adaptive immunity that is typically required to organize granulomas. The C. violaceum-induced granuloma requires at least two separate defense pathways, gasdermin D and iNOS, to maintain the integrity of the granuloma architecture. This innate granuloma successfully eradicates C. violaceum infection. Therefore, this C. violaceum-induced granuloma model demonstrates that innate immune cells successfully organize a granuloma and thereby resolve infection by an environmental pathogen.

Pyroptosis modulation by bacterial effector proteins

Pyroptosis is a proinflammatory form of programmed cell death featured with membrane pore formation that causes cellular swelling and allows the release of intracellular inflammatory mediators. This cell death process is elicited by the activation of the pore-forming proteins named gasdermins, and is intricately orchestrated by diverse regulatory factors in mammalian hosts to exert a prompt immune response against infections. However, growing evidence suggests that bacterial pathogens have evolved to regulate host pyroptosis for evading immune clearance and establishing progressive infection. In this review, we highlight current understandings of the functional role and regulatory network of pyroptosis in host antibacterial immunity. Thereafter, we further discuss the latest advances elucidating the mechanisms by which bacterial pathogens modulate pyroptosis through adopting their effector proteins to drive infections. A better understanding of regulatory mechanisms underlying pyroptosis at the interface of host-bacterial interactions will shed new light on the pathogenesis of infectious diseases and contribute to the development of promising therapeutic strategies against bacterial pathogens.

Mechanism of the Mongolian medicine Eerdun Wurile basic formula in improving postoperative cognitive dysfunction by inhibiting apoptosis through the SIRT1/p53 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The Mongolian medicine Eerdun Wurile is a commonly used Mongolian in folk medicine used to treat cerebral nervous system diseases such as cerebral hemorrhage, cerebral thrombosis, nerve injury and cognitive function, cardiovascular diseases such as hypertension and coronary heart disease. Eerdun wurile may effect anti-postoperative cognitive function.

AIM OF THE STUDY

To investigate the molecular mechanism of the Mongolian medicine Eerdun Wurile Basic Formula (EWB) in improving postoperative cognitive dysfunction (POCD) based on Network pharmacology, and to confirm involvement of the SIRT1/p53 signal pathway, one of the key signal pathways, by using the POCD mouse model.

MATERIAL AND METHODS

Obtain compounds and disease-related targets through TCMSP, TCMID, PubChem, PharmMapper platforms, GeneCards, and OMIM databases, and screen intersection genes; Use Cytoscape software to build a "drug-ingredient-disease-target" network, and the STRING platform for protein interaction analysis.; R software was used to analyze the function of gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment.; AutoDock Vina software for active components and core targets to Perform molecular docking. The POCD mouse model was prepared by intracerebroventricular injection of lipopolysaccharide (LPS), and the morphological changes of hippocampal tissue were observed by hematoxylin-eosin (HE) staining, Western blot, immunofluorescence and TUNEL were used to verify the results of network pharmacological enrichment analysis.

RESULTS

There were 110 potential targets for improving POCD by EWB, 117 items were enriched by GO, and 113 pathways were enriched by KEGG, among which the SIRT1/p53 signaling pathway was related to the occurrence of POCD. Quercetin, kaempferol, vestitol, β-sitosterol and 7-methoxy-2-methyl isoflavone in EWB can form stable conformations with low binding energy with core target proteins IL-6, CASP3, VEGFA, EGFR and ESR1. Animal experiments showed that compared with the POCD model group, the EWB group could significantly improve the apoptosis in the hippocampus of the mice, and significantly down-regulate the expression of Acetyl-p53 protein (P < 0.05).

CONCLUSION

EWB can improve POCD with the characteristics of multi-component, multi-target, and multi-pathway synergistic effects. Studies have confirmed that EWB can improve the occurrence of POCD by regulating the expression of genes related to the SIRT1/p53 signal pathway, which provides a new target and basis for the treatment of POCD.

The ever-increasing necessity of mass spectrometry in dissecting protein post-translational modifications catalyzed by bacterial effectors

Protein post-translational modifications (PTMs), such as ADP-ribosylation and phosphorylation, regulate multiple fundamental biological processes in cells. During bacterial infection, effector proteins are delivered into host cells through dedicated bacterial secretion systems and can modulate important cellular pathways by covalently modifying their host targets. These strategies enable intruding bacteria to subvert various host processes, thereby promoting their own survival and proliferation. Despite rapid expansion of our understanding of effector-mediated PTMs in host cells, analytical measurements of these molecular events still pose significant challenges in the study of host-pathogen interactions. Nevertheless, with major technical breakthroughs in the last two decades, mass spectrometry (MS) has evolved to be a valuable tool for detecting protein PTMs and mapping modification sites. Additionally, large-scale PTM profiling, facilitated by different enrichment strategies prior to MS analysis, allows high-throughput screening of host enzymatic substrates of bacterial effectors. In this review, we summarize the advances in the studies of two representative PTMs (i.e., ADP-ribosylation and phosphorylation) catalyzed by bacterial effectors during infection. Importantly, we will discuss the ever-increasing role of MS in understanding these molecular events and how the latest MS-based tools can aid in future studies of this booming area of pathogenic bacteria-host interactions.

Ca2+-calmodulin signalling at the host-pathogen interface

Multiple eukaryotic cell processes are modulated by calcium ions (Ca²⁺). As such, Ca²⁺ is emerging as a crucial regulator of innate immunity in multicellular organisms. In particular, recent studies have identified roles of Ca²⁺ signalling at the host-bacteria interface. Following microbial exposure, Ca²⁺ signals mobilised from the extracellular milieu or intracellular stores are transduced into cell physiological responses. However, during infection with host-adapted pathogens, Ca²⁺ signals are often atypical, due to the activities of virulence factors, with varied consequences for both the pathogen and the host cell. In this review, we describe the Ca²⁺-dependent host factors regulating antibacterial immunity, in addition to bacterial effectors that promote, inhibit, or co-opt Ca²⁺-calmodulin signalling to promote infection.

An innate granuloma eradicates an environmental pathogen using Gsdmd and Nos2

Granulomas often form around pathogens that cause chronic infections. Here, we discover a novel granuloma model in mice. Chromobacterium violaceum is an environmental bacterium that stimulates granuloma formation that not only successfully walls off but also clears the infection. The infected lesion can arise from a single bacterium that replicates in the presence of a neutrophil swarm. Bacterial replication ceases when macrophages organize around the infection and form a granuloma. This granuloma response is accomplished independently of adaptive immunity that is typically required to organize granulomas. The C. violaceum -induced granuloma requires at least two separate defense pathways, gasdermin D and iNOS, to maintain the integrity of the granuloma architecture. These innate granulomas successfully eradicate C. violaceum infection. Therefore, this new C. violaceum -induced granuloma model demonstrates that innate immune cells successfully organize a granuloma and thereby eradicate infection by an environmental pathogen.

Structural mechanisms of calmodulin activation of Shigella effector OspC3 to ADP-riboxanate caspase-4/11 and block pyroptosis

The caspase-4/11-GSDMD pyroptosis axis recognizes cytosolic lipopolysaccharide for antibacterial defenses. Shigella flexneri employs an OspC3 effector to block pyroptosis by catalyzing NAD⁺-dependent arginine ADP-riboxanation of caspase-4/11. Here, we identify Ca²⁺-free calmodulin (CaM) that binds and stimulates OspC3 ADP-riboxanase activity. Crystal structures of OspC3-CaM and OspC3-caspase-4 binary complexes reveal unique CaM binding to an OspC3 N-terminal domain featuring an ADP-ribosyltransferase-like fold and specific recognition of caspase-4 by an OspC3 ankryin repeat domain, respectively. CaM-OspC3-caspase-4 ternary complex structures show that NAD⁺ binding reorganizes the catalytic pocket, in which D231 and D177 activate the substrate arginine for initial ADP-ribosylation and ribosyl 2'-OH in the ADP-ribosylated arginine, respectively, for subsequent deamination. We also determine structures of unmodified and OspC3-ADP-riboxanated caspase-4. Mechanisms derived from this series of structures covering the entire process of OspC3 action are supported by biochemical analyses in vitro and functional validation in S. flexneri-infected mice.

Potential Oral Anticancer Therapeutic Agents of Hexahydrocurcumin-Encapsulated Chitosan Nanoparticles against MDA-MB-231 Breast Cancer Cells

Hexahydrocurcumin-encapsulated chitosan nanoparticles (HHC-CS-NPs) were formulated by oil-in-water emulsification and ionotropic gelation and optimized using the Box-Behnken design. The particle size, zeta potential, and encapsulation efficiency of the optimized HHC-CS-NPs were 256 ± 14 nm, 27.3 ± 0.7 mV, and 90.6 ± 1.7%, respectively. The TEM analysis showed a spherical shape and a dense structure with a narrow size distribution. The FT-IR analysis indicated no chemical interaction between the excipients and the drugs in the nanoparticles, but the existence of the drugs was molecularly dispersed in the nanoparticle matrices. The drug release profile showed a preliminary burst release followed by a sustained release under simulated gastrointestinal (GI) and physiological conditions. A stability study suggested that the HHC-CS-NPs were stable under UV light, simulated GI, and body fluids. The in vitro bioaccessibility and bioavailability of the HHC-CS-NPs were 2.2 and 6.1 times higher than those of the HHC solution, respectively. The in vitro evaluation of the antioxidant, anti-inflammatory, and cytotoxic effects of the optimized HHC-CS-NPs demonstrated that the CS-NPs significantly improved the biological activities of HHC in radical scavenging, hemolysis protection activity, anti-protein denaturation, and cytotoxicity against MDA-MB-231 breast cancer cells. Western blot analysis showed that the apoptotic protein expression of Bax, cytochrome C, caspase-3, and caspase-9, were significantly up-regulated, whereas the anti-apoptotic protein Bcl-2 expression was down-regulated in the HHC-CS-NP-treated cells. Our findings suggest that the optimized HHC-CS-NPs can be further developed as an efficient oral treatment for breast cancer.

Structural insights into caspase ADPR deacylization catalyzed by a bacterial effector and host calmodulin

Programmed cell death and caspase proteins play a pivotal role in host innate immune response combating pathogen infections. Blocking cell death is employed by many bacterial pathogens as a universal virulence strategy. CopC family type III effectors, including CopC from an environmental pathogen Chromobacterium violaceum, utilize calmodulin (CaM) as a co-factor to inactivate caspases by arginine ADPR deacylization. However, the molecular basis of the catalytic and substrate/co-factor binding mechanism is unknown. Here, we determine successive cryo-EM structures of CaM-CopC-caspase-3 ternary complex in pre-reaction, transition, and post-reaction states, which elucidate a multistep enzymatic mechanism of CopC-catalyzed ADPR deacylization. Moreover, we capture a snapshot of the detachment of modified caspase-3 from CopC. These structural insights are validated by mutagenesis analyses of CopC-mediated ADPR deacylization in vitro and animal infection in vivo. Our study offers a structural framework for understanding the molecular basis of arginine ADPR deacylization catalyzed by the CopC family.

Ferroptosis, necroptosis, and pyroptosis in the occurrence and development of ovarian cancer

Ovarian cancer (OC) is one of the most common malignancies that causes death in women and is a heterogeneous disease with complex molecular and genetic changes. Because of the relatively high recurrence rate of OC, it is crucial to understand the associated mechanisms of drug resistance and to discover potential target for rational targeted therapy. Cell death is a genetically determined process. Active and orderly cell death is prevalent during the development of living organisms and plays a critical role in regulating life homeostasis. Ferroptosis, a novel type of cell death discovered in recent years, is distinct from apoptosis and necrosis and is mainly caused by the imbalance between the production and degradation of intracellular lipid reactive oxygen species triggered by increased iron content. Necroptosis is a regulated non-cysteine protease–dependent programmed cell necrosis, morphologically exhibiting the same features as necrosis and occurring via a unique mechanism of programmed cell death different from the apoptotic signaling pathway. Pyroptosis is a form of programmed cell death that is characterized by the formation of membrane pores and subsequent cell lysis as well as release of pro-inflammatory cell contents mediated by the abscisin family. Studies have shown that ferroptosis, necroptosis, and pyroptosis are involved in the development and progression of a variety of diseases, including tumors. In this review, we summarized the recent advances in ferroptosis, necroptosis, and pyroptosis in the occurrence, development, and therapeutic potential of OC.

A family of conserved bacterial virulence factors dampens interferon responses by blocking calcium signaling

Interferons (IFNs) induce an antimicrobial state, protecting tissues from infection. Many viruses inhibit IFN signaling, but whether bacterial pathogens evade IFN responses remains unclear. Here, we demonstrate that the Shigella OspC family of type-III-secreted effectors blocks IFN signaling independently of its cell death inhibitory activity. Rather, IFN inhibition was mediated by the binding of OspC1 and OspC3 to the Ca2+ sensor calmodulin (CaM), blocking CaM kinase II and downstream JAK/STAT signaling. The growth of Shigella lacking OspC1 and OspC3 was attenuated in epithelial cells and in a murine model of infection. This phenotype was rescued in both models by the depletion of IFN receptors. OspC homologs conserved in additional pathogens not only bound CaM but also inhibited IFN, suggesting a widespread virulence strategy. These findings reveal a conserved but previously undescribed molecular mechanism of IFN inhibition and demonstrate the critical role of Ca2+ and IFN targeting in bacterial pathogenesis.

Maintaining home integrity by bacterial pathogens: Disruption for the sake of construction

Caspases are often considered the final checkpoint for a pathogen to save its replicative niche from collapsing after cell death signaling has been initiated in response to infection. Two recent works (Li et al., 2021; Peng et al., 2022) found that pathogens inhibit host cell death by inactivating multiple caspases with a novel posttranslational modification.