The interplay between BAX and BAK tunes apoptotic pore growth to control mitochondrial-DNA-mediated inflammation

Mitochondrial Dysfunction is a Crucial Immune Checkpoint for Neuroinflammation and Neurodegeneration: mtDAMPs in Focus

Neuroinflammation is a pivotal factor in the progression of both age-related and acute neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and stroke. Mitochondria, essential for neuronal health due to their roles in energy production, calcium buffering, and oxidative stress regulation, become increasingly susceptible to dysfunction under conditions of metabolic stress, aging, or injury. Impaired mitophagy in aged or injured neurons leads to the accumulation of dysfunctional mitochondria, which release mitochondrial-derived damage-associated molecular patterns (mtDAMPs). These mtDAMPs act as immune checkpoints, activating pattern recognition receptors (PRRs) and triggering innate immune signaling pathways. This activation initiates inflammatory responses in neurons and brain-resident immune cells, releasing cytokines and chemokines that damage adjacent healthy neurons and recruit peripheral immune cells, further amplifying neuroinflammation and neurodegeneration. Long-term mitochondrial dysfunction perpetuates a chronic inflammatory state, exacerbating neuronal injury and contributing additional immunogenic components to the extracellular environment. Emerging evidence highlights the critical role of mtDAMPs in initiating and sustaining neuroinflammation, with circulating levels of these molecules potentially serving as biomarkers for disease progression. This review explores the mechanisms of mtDAMP release due to mitochondrial dysfunction, their interaction with PRRs, and the subsequent activation of inflammatory pathways. We also discuss the role of mtDAMP-triggered innate immune responses in exacerbating both acute and chronic neuroinflammation and neurodegeneration. Targeting dysfunctional mitochondria and mtDAMPs with pharmacological agents presents a promising strategy for mitigating the initiation and progression of neuropathological conditions.

cGAMP-targeting injectable hydrogel system promotes periodontal restoration by alleviating cGAS-STING pathway activation

The impaired function of periodontal ligament stem cells (PDLSCs) impedes restoration of periodontal tissues. The cGAS-cGAMP-STING pathway is an innate immune pathway that sensing cytosolic double-stranded DNA (dsDNA), but its role in regulating the function of PDLSCs is still unclear. In this study, we found that mitochondrial DNA (mtDNA) was released into the cytoplasm through the mitochondrial permeability transition pore (mPTP) in PDLSCs upon inflammation, which binds to cGAS and activated the STING pathway by promoting the production of cGAMP, and ultimately impaired the osteogenic differentiation of PDLSCs. Additionally, it is first found that inflammation can down-regulate the level of the ATP-binding cassette membrane subfamily member C1 (ABCC1, a cGAMP exocellular transporter) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1, a cGAMP hydrolase), which further aggravated the accumulation of intracellular cGAMP, leading to the persistent activation of the cGAS-STING pathway and thus the impaired the differentiation capacity of PDLSCs. Furthermore, we designed a hydrogel system loaded with a mPTP blocker, an ABCC1 agonist and ENPP1 to promote periodontal tissue regeneration by modulating the production, exocytosis, and clearance of cGAMP. In conclusion, our results highlight the profound effects, and specific mechanisms, of the cGAS-STING pathway on the function of stem cells and propose a new strategy to promote periodontal tissue restoration based on the reestablishment of cGAMP homeostasis.

Mitochondria and cell death signalling

Mitochondria are essential organelles in the life and death of a cell. During apoptosis, mitochondrial outer membrane permeabilisation (MOMP) engages caspase activation and cell death. Under nonlethal apoptotic stress, some mitochondria undergo permeabilisation, termed minority MOMP. Nonlethal apoptotic signalling impacts processes including genome stability, senescence and innate immunity. Recent studies have shown that upon MOMP, mitochondria and consequent signalling can trigger inflammation. We discuss how this occurs, and how mitochondrial inflammation might be targeted to increase tumour immunogenicity. Finally, we highlight how mitochondria contribute to other types of cell death including pyroptosis and ferroptosis. Collectively, these studies reveal critical new insights into how mitochondria regulate cell death, highlighting that mitochondrial signals engaged under nonlethal apoptotic stress have wide-ranging biological functions.

Piperlongumine mediated apoptosis in cervical cancer cells beyond docking predictions

Cervical cancer is the 4th most prevalent cancer in women. Despite its global health impact, cervical cancer research has achieved limited success with various therapies (chemo, radio, chemo-radio, surgery, etc.). Recent decades have seen no improvement in survival rates due to cancer recurrence and long-term health concerns. These treatments show the need for a new herbal approach as alternative therapy for cancer. Piperlongumine is one of numerous perfected phytochemicals with anticancerous properties. In this study, in silico simulations demonstrate various novel properties of Piperlongumine. Molecular docking was performed between receptor and ligand by simulating molecular interactions in the pro and anti-apoptotic proteins B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and Bcl-2 antagonist/killer (Bak). The docking scores of Piperlongumine with Bcl-2, Bak, and Bax are -7.02, -6.78, and -7.54 kcal/mol, respectively. Piperlongumine was also bio-tested for anticancer activities against cervical cancer cells (SiHa). Piperlongumine showed compromised cell viability, promoted apoptosis, higher nuclear condensation, reduction in mitochondrial membrane potential, increase in reactive oxygen species level, promoted cell cycle arrest, upregulation of pro-apoptotic gene whereas downregulation of anti-apoptotic genes. In vitro studies revealed that Piperlongumine targets apoptotic pathway in cervical cancer and could be a possible effective treatment for cervical cancer. Additional in vivo research is needed to explore the potential of Piperlongumine to improve treatment outcomes.

Targeting mitochondria with natural polyphenols for treating Neurodegenerative Diseases: a comprehensive scoping review from oxidative stress perspective

Neurodegenerative diseases are a class of conditions with widespread detrimental impacts, currently lacking effective therapeutic drugs. Recent studies have identified mitochondrial dysfunction and the resultant oxidative stress as crucial contributors to the pathogenesis of neurodegenerative diseases. Polyphenols, naturally occurring compounds with inherent antioxidant properties, have demonstrated the potential to target mitochondria and mitigate oxidative stress. This therapeutic potential has garnered significant attention in recent years. Investigating the mitochondrial targeting capacity of polyphenols, their role in functional regulation, and their ability to modulate oxidative stress, along with exploring novel technologies and strategies for modifying polyphenol compounds and their formulations, holds promise for providing new avenues for the treatment of neurodegenerative diseases.

Granulosa cell death is a significant contributor to DNA-damaging chemotherapy-induced ovarian insufficiency†

Typically, DNA-damaging chemotherapy (CTx) regimens have a gonadotoxic effect and cause premature ovarian insufficiency (POI), characterized by infertility and estrogen deficiency. However, whether loss of granulosa cells killed directly by CTx contributes significantly to POI has not been determined. To address this issue, we used a previously established mouse model of CTx-induced POI. The alkylating drugs Busulfan (8.75 mg/kg) and Cyclophosphamide (100 mg/kg) were administered to 8-week-old FVB female mice by intraperitoneal (IP) injection three times at 48-h intervals, after which ovarian tissues were harvested and examined by immunofluorescence. The number of primordial follicles was significantly reduced at day (d)6, whereas the number of growing follicles was relatively unchanged. CTx led to DNA double strand breaks in both oocytes and granulosa cells based on the presence of γH2AX foci. However, markers of apoptosis predominantly labeled granulosa cells in growing follicles. We next examined the effect of inhibiting apoptosis in growing granulosa cells by generating Bak-/-Baxfx/fx; Cyp19a1Cre transgenic mice. On d10 after the first CTx, Bak-/-Baxfx/fx; Cyp19a1Cre ovaries had fewer apoptotic granulosa cells and more surviving follicles than controls. Furthermore, Bak-/-Baxfx/fx; Cyp19a1Cre mice showed better fertility than controls after CTx. Our data suggest that granulosa cell death is a significant contributor to follicle depletion and fertility loss after Cyclophosphamide and Busulfan.

The fucoidan delivery system enhanced the anti-cervical cancer effect of caffeic acid

Cervical cancer remains one of the leading causes of mortality among women, and immunotherapy targeting the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway holds promise for its treatment. This study has developed nanoparticles based on fucoidan (Fu/CA NPs), successfully loading them with caffeic acid (CA) for application in cervical cancer therapy. In vitro experiments revealed that Fu/CA NPs significantly inhibited the proliferation of cervical cancer HeLa cells (by 65.73 ± 4.06 %) and induced apoptosis through the accumulation of reactive oxygen species and mitochondrial damage. Furthermore, treatment with Fu/CA NPs activated the cGAS-STING pathway, attributed to the cytoplasmic release of mitochondrial DNA (mtDNA) and the induction of DNA double-strand breaks (dsDNA) by Fu/CA NPs. In vivo results confirmed that Fu/CA NPs suppressed solid tumor growth (by 67.8 %), with even more pronounced antitumor effects observed when combined with cisplatin (96.5 %), a phenomenon also associated with the activation of the cGAS-STING pathway. Excitingly, the combination of Fu/CA NPs and cisplatin alleviated cisplatin-induced nephrotoxicity, as indicated by a decrease in blood urea nitrogen (BUN) by 53.27 % and serum creatinine (SCr) by 74.93 %. In summary, our research presents a potential therapeutic avenue for cervical cancer treatment, particularly highlighting the synergistic benefits of combining Fu/CA NPs with cisplatin.

The role of cGAS-STING in remodeling the tumor immune microenvironment induced by radiotherapy

The activation of the cGAS-STING pathway occurs when tumor cell DNA is damaged by ionizing radiation. Once triggered, this pathway reshapes the tumor immune microenvironment by promoting the maturation, activation, polarization, and immune-killing capacity of immune cells, as well as by inducing the release of interferons and the expression of immune-related genes. In addition, the gut microbiota and various mechanisms of programmed cell death interact with the cGAS-STING pathway, further influencing its function in remodeling the immune microenvironment after radiotherapy. Therefore, investigating the mechanisms of the cGAS-STING pathway in reshaping the tumor immune microenvironment post-radiotherapy can not only optimize the efficacy of combined radiotherapy and immunotherapy but also provide new research directions and potential targets for cancer treatment.

Mitochondrial DNA signals driving immune responses: Why, How, Where?

There has been a recent expansion in our understanding of DNA-sensing mechanisms. Mitochondrial dysfunction, oxidative and proteostatic stresses, instability and impaired disposal of nucleoids cause the release of mitochondrial DNA (mtDNA) from the mitochondria in several human diseases, as well as in cell culture and animal models. Mitochondrial DNA mislocalized to the cytosol and/or the extracellular compartments can trigger innate immune and inflammation responses by binding DNA-sensing receptors (DSRs). Here, we define the features that make mtDNA highly immunogenic and the mechanisms of its release from the mitochondria into the cytosol and the extracellular compartments. We describe the major DSRs that bind mtDNA such as cyclic guanosine-monophosphate-adenosine-monophosphate synthase (cGAS), Z-DNA-binding protein 1 (ZBP1), NOD-, LRR-, and PYD- domain-containing protein 3 receptor (NLRP3), absent in melanoma 2 (AIM2) and toll-like receptor 9 (TLR9), and their downstream signaling cascades. We summarize the key findings, novelties, and gaps of mislocalized mtDNA as a driving signal of immune responses in vascular, metabolic, kidney, lung, and neurodegenerative diseases, as well as viral and bacterial infections. Finally, we define common strategies to induce or inhibit mtDNA release and propose challenges to advance the field.

The Role of N6-Methyladenosine in Mitochondrial Dysfunction and Pathology

Mitochondria are indispensable in cells and play crucial roles in maintaining cellular homeostasis, energy production, and regulating cell death. Mitochondrial dysfunction has various manifestations, causing different diseases by affecting the diverse functions of mitochondria in the body. Previous studies have mainly focused on mitochondrial-related diseases caused by nuclear gene mutations or mitochondrial gene mutations, or mitochondrial dysfunction resulting from epigenetic regulation, such as DNA and histone modification. In recent years, as a popular research area, m6A has been involved in a variety of important processes under physiological and pathological conditions. However, there are few summaries on how RNA methylation, especially m6A RNA methylation, affects mitochondrial function. Additionally, the role of m6A in pathology through influencing mitochondrial function may provide us with a new perspective on disease treatment. In this review, we summarize several manifestations of mitochondrial dysfunction and compile examples from recent years of how m6A affects mitochondrial function and its role in some diseases.

The BCL-2 protein family: from discovery to drug development

The landmark discovery of the BCL-2 gene and then its function marked the identification of inhibition of apoptotic cell death as a crucial novel mechanism driving cancer development and launched the quest to discover the molecular control of apoptosis. This work culminated in the generation of specific inhibitors that are now in clinical use, saving and improving tens of thousands of lives annually. Here, some of the original players of this story, describe the sequence of critical discoveries. The t(14;18) chromosomal translocation, frequently observed in follicular lymphoma, allowed the identification and the cloning of a novel oncogene (BCL-2) juxtaposed to the immunoglobulin heavy chain gene locus (IgH). Of note, BCL-2 acted in a distinct manner as compared to then already known oncogenic proteins like ABL and c-MYC. BCL-2 did not promote cell proliferation but inhibited cell death, as originally shown in growth factor dependent haematopoietic progenitor cell lines (e.g., FDC-P1) and in Eμ-Myc/Eμ-Bcl-2 double transgenic mice. Following a rapid expansion of the BCL-2 protein family, the Abbott Laboratories solved the first structure of BCL-XL and subsequently the BCL-XL/BAK peptide complex, opening the way to understanding the structures of other BCL-2 family members and, finally, to the generation of inhibitors of the different pro-survival BCL-2 proteins, thanks to the efforts of Servier/Norvartis, Genentech/WEHI, AbbVie, Amgen, Prelude and Gilead. Although the BCL-2 inhibitor Venetoclax is in clinical use and inhibitors of BCL-XL and MCL-1 are undergoing clinical trials, several questions remain on whether therapeutic windows can be achieved and what other agents should be used in combination with BH3 mimetics to achieve optimal therapeutic impact for cancer therapy. Finally, the control of the expression of BH3-only proteins and pro-survival BCL-2 family members needs to be better understood as this may identify novel targets for cancer therapy. This story is still not concluded!

A novel biosensor for the spatiotemporal analysis of STING activation during innate immune responses to dsDNA

The cGAS-STING signalling pathway has a central role in the innate immune response to extrinsic and intrinsic sources of cytoplasmic dsDNA. At the core of this pathway is cGAS-dependent production of the intra- and extra-cellular messenger cGAMP, which activates STING and leads to IRF3-dependent expression of cytokines and interferons. Despite its relevance to viral and bacterial infections, cell death, and genome instability, the lack of specific live-cell reporters has precluded spatiotemporal analyses of cGAS-STING signalling. Here, we generate a fluorescent biosensor termed SIRF (STING-IRF3), which reports on the functional interaction between activated STING and IRF3 at the Golgi. We show that cells harbouring SIRF react in a time- and concentration-dependent manner both to STING agonists and to microenvironmental cGAMP. We demonstrate that the new biosensor is suitable for single-cell characterisation of immune responses to HSV-1 infection, mtDNA release upon apoptosis, or other sources of cytoplasmic dsDNA. Furthermore, our results indicate that STING signalling is not activated by ruptured micronuclei, suggesting that other cytosolic pattern recognition receptors underlie the interferon responses to chromosomal instability.

Nanomedicine Penetrating Blood-Pancreas Barrier for Effective Treatment of Acute Pancreatitis

Acute pancreatitis (AP) is a primary contributor to hospitalization and in-hospital mortality worldwide. Targeted elimination of mitochondrial reactive oxygen species (mtROS) within pancreatic acinar cells (PACs) represents an ideal strategy for treating AP. However, existing drugs fail to overcome the physiological barriers of the pancreas to effectively reach PACs mitochondria due to the trade-off between conventional positively charged mitochondrial-targeting groups and their inability to penetrate the blood-pancreas barrier (BPB). Here, a tungsten-based heteropolyacid nano-antioxidant (mTWNDs) is introduced, co-modified with tannic acid (TA) and melanin, enabling site-specific clearance of mtROS in PACs, offering a highly effective treatment for AP. TA exhibits a strong affinity for proline-rich type III collagen and the mitochondrial outer membrane protein TOM20. This unique property allows mTWNDs to traverse the damaged BPB-exposing type III collagen to reach PACs and subsequently penetrate mitochondria for targeted mtROS elimination. In cerulein-induced AP mice, mTWNDs reversed AP at 1/50th the dose of N-acetylcysteine, suppressing PACs apoptosis and inflammation by blocking the stimulator of the interferon genes pathway activation in macrophage. This study establishes a mitochondrial-targeting antioxidant nanomedicine strategy for AP treatment.

Mitochondrial DNA in Exercise-Mediated Innate Immune Responses

Mitochondria are considered as "the plant of power" with cells for a long time. However, recent researches suggest that mitochondria also take part in innate immune response to a great extent. Remarkably, mtDNA was reported to have immunnostimulatory potential in 2004. Since then, there has been rapid growth in understanding the role of mtDNA in innate immune. The mtDNA is released into cytosol, extracellular environment, or circulating blood through BAK/BAX pore, mPTP, and GSDMD pore upon mitochondrial damage, where it is recognized by PRRs including TLR9, cGAS, and NLRP3, thereby triggering innate immune response. On the other hand, regular exercise has been recognized as an effective intervention strategy for innate immune response. Some studies show that chronic moderate-intensity endurance exercise, resistance training, HIIT, and moderate-intensity acute exercise enhance mitochondrial function by promoting mtDNA transcription and replication, thus blunting the abnormal release of mtDNA and excessive innate immune response. On the contrary, high-intensity acute exercise elicits the opposite effect. Nevertheless, only a very small body of research by far has been performed to illustrate the impact of exercise on mtDNA-driven innate immune response, and an overall review is lacking. In light of these, we summarize the current knowledge on the mechanism mediating the release of mtDNA, the role of mtDNA in innate immune response and the influence of exercise on mtDNA leakage, hoping to pave the way to investigate new diagnostic and therapeutic approaches for immunopathies.

Cellular Discrepancy of Platinum Complexes in Interfering with Mitochondrial DNA

Mitochondria are associated with cellular energy metabolism, proliferation, and mode of death. Damage to mitochondrial DNA (mtDNA) greatly affects mitochondrial function by interfering with energy production and the signaling pathway. Monofunctional trinuclear platinum complex MTPC demonstrates different actions on the mtDNA of cancerous and normal cells. It severely impairs the integrity and function of mitochondria in the human lung cancer A549 cells, such as dissipating mitochondrial membrane potential, decreasing the copy number of mtDNA, interfering in nucleoid proteins and polymerase gamma gene, reducing adenosine triphosphate (ATP), and inducing mitophagy, whereas it barely affects the mtDNA of the human kidney 2 (HK-2) cells. Moreover, MTPC promotes the release of mtDNA into the cytosol and stimulates the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, thus showing the potential to trigger antitumor immunity. MTPC displays significant cytotoxicity against A549 cells, while it exhibits weak toxicity toward HK-2 cells, therefore displaying great advantage to overcome the lingering nephrotoxicity of platinum anticancer drugs. Discrepant effects of a metal complex on mitochondria of different cells mean that targeting mitochondria has special significance in cancer therapy.

Cytosolic nucleic acid sensing as driver of critical illness: mechanisms and advances in therapy

Nucleic acids from both self- and non-self-sources act as vital danger signals that trigger immune responses. Critical illnesses such as acute respiratory distress syndrome, sepsis, trauma and ischemia lead to the aberrant cytosolic accumulation and massive release of nucleic acids that are detected by antiviral innate immune receptors in the endosome or cytosol. Activation of receptors for deoxyribonucleic acids and ribonucleic acids triggers inflammation, a major contributor to morbidity and mortality in critically ill patients. In the past decade, there has been growing recognition of the therapeutic potential of targeting nucleic acid sensing in critical care. This review summarizes current knowledge of nucleic acid sensing in acute respiratory distress syndrome, sepsis, trauma and ischemia. Given the extensive research on nucleic acid sensing in common pathological conditions like cancer, autoimmune disorders, metabolic disorders and aging, we provide a comprehensive summary of nucleic acid sensing beyond critical illness to offer insights that may inform its role in critical conditions. Additionally, we discuss potential therapeutic strategies that specifically target nucleic acid sensing. By examining nucleic acid sources, sensor activation and function, as well as the impact of regulating these pathways across various acute diseases, we highlight the driving role of nucleic acid sensing in critical illness.

The neuroimmune nexus: unraveling the role of the mtDNA-cGAS-STING signal pathway in Alzheimer's disease

The relationship between Alzheimer's disease (AD) and neuroimmunity has gradually begun to be unveiled. Emerging evidence indicates that cyclic GMP-AMP synthase (cGAS) acts as a cytosolic DNA sensor, recognizing cytosolic damage-associated molecular patterns (DAMPs), and inducing the innate immune response by activating stimulator of interferon genes (STING). Dysregulation of this pathway culminates in AD-related neuroinflammation and neurodegeneration. A substantial body of evidence indicates that mitochondria are involved in the critical pathogenic mechanisms of AD, whose damage leads to the release of mitochondrial DNA (mtDNA) into the extramitochondrial space. This leaked mtDNA serves as a DAMP, activating various pattern recognition receptors and immune defense networks in the brain, including the cGAS-STING pathway, ultimately leading to an imbalance in immune homeostasis. Therefore, modulation of the mtDNA-cGAS-STING pathway to restore neuroimmune homeostasis may offer promising prospects for improving AD treatment outcomes. In this review, we focus on the mechanisms of mtDNA release during stress and the activation of the cGAS-STING pathway. Additionally, we delve into the research progress on this pathway in AD, and further discuss the primary directions and potential hurdles in developing targeted therapeutic drugs, to gain a deeper understanding of the pathogenesis of AD and provide new approaches for its therapy.

Apoptosis signaling is activated as a transient pulse in neurons

Apoptosis is a fundamental process of all mammalian cells but exactly how it is regulated in different primary cells remains less explored. In most contexts, apoptosis is engaged to eliminate cells. However, postmitotic cells such as neurons must efficiently balance the need for developmental apoptosis versus the physiological needs for their long-term survival. Neurons are capable of reversing the commitment to death even after the point of cytochrome c release. This ability of neurons to recover from an apoptotic signal suggests that activation of the apoptotic pathway in neurons could be much more transient than is currently recognized. Here, we investigated whether the apoptotic pathway in neurons is a persistent signal or a transient pulse in continuous presence of apoptotic stimulus. We have examined this at three key steps in apoptotic signaling: phosphorylation of c-Jun, induction of the BH3-only family proteins and Bax activation. Strikingly, we found all three of these events occur as transient signals following Nerve Growth Factor (NGF) deprivation-induced apoptosis in sympathetic neurons. This transient apoptosis signal would effectively allow neurons to reset and permit recovery if the apoptotic stimulus is reversed. Excitingly, we have also discovered that a neuron's ability to recover from an apoptotic signal is dependent on expression of the anti-apoptotic Bcl-2 family protein Bcl-xL. Bcl-xL-deficient neurons lose the ability to recover from NGF deprivation even if NGF is restored. Additionally, we show that recovery from a previous exposure to NGF deprivation is protective against subsequent deprivation. Together, these results define a novel mechanism by which apoptosis is regulated in neurons where the transient pulse of the apoptotic signaling supports neuronal resilience.

Mitochondrial Amount Determines Doxorubicin-Induced Cardiotoxicity in Cardiomyocytes

Doxorubicin, an anthracycline commonly used for treating cancer patients, is known for its cardiotoxic side-effects. Although dose-dependent, but susceptibility remains variable among patients, and childhood-exposure-adult-onset remains challenging. Besides topoisomerase toxicity, Doxorubicin is also toxic to the mitochondria yet the underlying late onset mechanism remains elusive. Here, it is observed that the mitochondrial copy number in PBMCs of patients treated with anthracycline chemotherapy is negatively correlated with the change in plasma BNP levels after treatment. Isogenic hiPSC-CMs are generated with high, norm, and low mitochondrial copy numbers using mitochondrial transplantation and the YFP-Parkin system. Remarkably, lower mitochondria copy number translates to lower IC50, suggesting increased susceptibility. Mitochondria supplementation by intramyocardial injection prevents doxorubicin induced heart failure. Mechanistically, doxorubicin treatment leads to mPTP opening and mitochondrial DNA (mtDNA) leakage. This mtDNA leakage event activates the cGAS-STING pathway and drives inflammation and myocardial senescence. Cardiomyocyte-specific knockout of Sting (Myh6-Cre/Stingflox/flox; StingCKO) and over expression of mitochondrial tagged DNase1 in mice partially rescue doxorubicin-induced cardiac dysfunction. In conclusion, the work establishes a negative correlation between cardiomyocyte mitochondrial copy number and doxorubicin toxicity. Molecularly, it is demonstrated that mtDNA leakage activates cGAS-STING pathway and accelerates myocardial dysfunction. These insights offer new co-administration strategies for cancer patients.

Novel Camptothecin Derivative 9c with Enhanced Antitumor Activity via NSA2-EGFR-P53 Signaling Pathway

Therapeutic challenges persist in the management of non-small cell lung cancer (NSCLC) in oncology. Camptothecins have demonstrated as crucial agents in tumor therapy; however, their efficacy is significantly hindered by adverse effects and drug resistance. Herein, we present a novel camptothecin derivative named 9c, which exhibits impressive anti-NSCLC potency surpassing the widely recognized camptothecin analog FL118 through a novel mechanism. Our findings demonstrated that 9c effectively inhibited tumor malignancy through cell cycle arrest and apoptosis induction with the transcriptional downregulation of anti-apoptotic genes including survivin, Mcl-1, Bcl-2, and XIAP. Mechanistically, 9c induced a wild-type p53 expression by destabilizing the NSA2-EGFR axis, thus delaying the cell cycle progression and ultimately triggering apoptosis. 9c significantly inhibited the growth of the NSCLC xenograft in vivo without observed side toxicity. Importantly, it complemented the therapeutic advantages of the novel drug AMG510 for addressing KRAS-mutant NSCLC. Collectively, these findings position 9c as a promising candidate with innovative approaches to combat NSCLC.

Dexmedetomidine ameliorates hepatic ischemia reperfusion injury via modulating SIRT3 mediated mitochondrial quality control

Ischaemia-reperfusion (IR) damage is an inevitable adverse effect of liver surgery. Recent research has found that IR damage is involved in severe mitochondrial dysfunction. Mitochondrial biosynthesis and dynamics control mitochondrial mass, distribution, and function. Sirtuin 3 (SIRT3) is widely known for preserving health and functionality of mitochondria. DEX has been proven to alleviate liver damage through antioxidant and anti-apoptotic pathways. But it's unclear how DEX protects mitochondria at this time. In this research, the mechanism behind the protective benefits of DEX was examined using the rat liver IR model and the rat liver cells (BRL-3 A) hypoxia reoxygenation (HR) model. We discovered that DEX treatment restored mitochondrial membrane potential, promoted ATP production, prevented oxidative stress, and decreased apoptosis in BRL-3 A cells. Furthermore, HR damage increased mitochondrial fission while decreasing mitochondrial fusion and biogenesis in BRL-3 A cells, which DEX partially corrected. The benefits of DEX on mitochondrial protection were reversed after addition of SR-18,292. Additionally, DEX showed the ability to enhance SIRT3 expression, and after cells were transfected with SIRT3 siRNA, DEX's effects on mitochondria were partially prevented. Similarly, in the rat model, DEX alleviating liver histopathological injury and oxidative stress. DEX inhibited IR-induced mitochondrial damage through improving ETC complex I- IV activities and ATP content, reducing apoptosis, controlling mitochondrial quality, and upregulating the expression of SIRT3. Additionally, our research shows that DEX's ability to protect the liver against IR damage is mediated by the modulation of mitochondrial quality control. Overall, the modification of SIRT3 activity could be responsible for this outcome.

Mitochondrial DNA leakage: underlying mechanisms and therapeutic implications in neurological disorders

Mitochondrial dysfunction is a pivotal instigator of neuroinflammation, with mitochondrial DNA (mtDNA) leakage as a critical intermediary. This review delineates the intricate pathways leading to mtDNA release, which include membrane permeabilization, vesicular trafficking, disruption of homeostatic regulation, and abnormalities in mitochondrial dynamics. The escaped mtDNA activates cytosolic DNA sensors, especially cyclic gmp-amp synthase (cGAS) signalling and inflammasome, initiating neuroinflammatory cascades via pathways, exacerbating a spectrum of neurological pathologies. The therapeutic promise of targeting mtDNA leakage is discussed in detail, underscoring the necessity for a multifaceted strategy that encompasses the preservation of mtDNA homeostasis, prevention of membrane leakage, reestablishment of mitochondrial dynamics, and inhibition the activation of cytosolic DNA sensors. Advancing our understanding of the complex interplay between mtDNA leakage and neuroinflammation is imperative for developing precision therapeutic interventions for neurological disorders.

Unraveling the interplay between meningitis and mitochondria: Etiology, pathogenesis, and therapeutic insights

Meningitis, characterized by an inflammatory response affecting the membranes surrounding the brain and spinal cord, poses a formidable challenge to global public health. Its etiology spans a spectrum of infectious agents, ranging from bacteria, to viruses, fungi, and parasites. Concurrently, mitochondria-traditionally known as 'cellular powerhouses'-have emerged as critical players in various essential biological functions, including but not limited to, energy production, metabolic regulation, and cell fate determination. Emerging evidence suggests that mitochondria may play vital roles in the pathogenesis of meningitis. In this review, we delineated the definition, classification, etiology, pathogenesis, and clinical manifestations of meningitis, and elucidated the structure, dynamics and functions of mitochondria. We subsequently delved into the intricate interplay between meningitis and mitochondria, identifying potential therapeutic interventions targeting mitochondria for the first time. With clinical trials on the horizon, our review lays the foundation for a transformative era in meningitis therapeutics, where unraveling the intricate interplay between meningitis and mitochondria offers promise for mitigating neuroinflammation and improving patient outcomes.

Functionalized Nanozyme Microcapsules Targeting Deafness Prevention via Mitochondrial Homeostasis Remodeling

Mitochondrial dysfunction, which is the primary mechanism underlying cisplatin-induced hearing loss, can potentially be mitigated by modulating the redox balance and reprogramming the energy metabolism to remodel mitochondrial homeostasis. Herein, N-acetyl-l-cysteine-derived carbonized polymer dots (NAC CPDs) are embedded into manganese porphyrin-doped metal-organic frameworks and encapsulated using a polydopamine (PDA) coating and gelatin methacryloyl (GelMA) hydrogel to afford functionalized nanozyme microcapsules. Owing to their injectability and adhesion properties, these microcapsules exhibit the advantages of prolonged retention in the middle ear and sustained release in the inner ear. The synergy between the manganese porphyrin and polymer dots results in excellent antioxidant properties. The developed nanozymes activate the PI3K-AKT pathway, reprogramming the energy supply mechanism, and inhibiting the oligomerization of BAX in mitochondria to prevent the leakage of mitochondrial DNA and cytochrome c. Therapeutic efficacy and related mechanisms are validated in vivo. Thus, this study on mitochondrial homeostasis remodeling by nanozyme microcapsules opens a new chapter in the treatment of hearing loss.

Triptolide exposure triggers ovarian inflammation by activating cGAS-STING pathway and decrease oocyte quality in mouse

Triptolide (TPL), a prominent bioactive constituent derived from the Chinese herb Tripterygium wilfordii, exhibits diverse pharmacological effects such as anti-tumor and anti-immune properties. Despite its extensive clinical application for the treatment of arthritis and immune disorders, TPL has been associated with multiorgan toxicity, including adverse effects on the female reproductive system. However, the precise mechanisms underlying TPL-induced ovarian damage remain poorly understood. In this study, employing a mouse toxicological model, exposure to TPL was observed to result in decreased ovarian coefficient and fertility. Subsequent research demonstrated TPL exposure affected mitochondrial function, increased mitochondrial outer membrane permeability, resulted in mtDNA releasing into the cytoplasm. These events subsequently activated cGAS-STING pathway, leading to ovarian inflammation. Furthermore, TPL exposure has been found to disrupt the meiotic maturation of oocytes, which is mechanistically associated with suboptimal morphology of spindle and microtubule organizing centers (MTOCs). This association has been further confirmed through the use of reduced representation bisulfite sequencing (RRBS). In conclusion, our study demonstrates that TPL exposure can hinder follicular development, resulting in ovarian inflammation and reduced oocyte quality.

Mitochondrial damage causes inflammation via cGAS-STING signaling in ketamine-induced cystitis

BACKGROUND

Mitochondrial dysfunction and damage can result in the release of mitochondrial DNA (mtDNA) into the cytoplasm, which subsequently activates the cGAS-STING pathway, promoting the onset of inflammatory diseases. Various factors, such as oxidative stress, viral infection, and drug toxicity, have been identified as inducers of mitochondrial damage. This study aims to investigate the role of mtDNA as a critical inflammatory mediator in the pathogenesis of ketamine (KET)-induced cystitis (KC) through the cGAS-STING pathway.

METHODS

To investigate the role of the cGAS-STING pathway in KET-induced cystitis, we assessed the expression of cGAS and STING in rats with KET cystitis. Additionally, we evaluated STING expression in conditionally deficient Simian Virus-transformed Human Uroepithelial Cell Line 1 (SV-HUC-1) cells in vitro. Morphological changes in mitochondria were examined using transmission electron microscopy. We measured intracellular reactive oxygen species (ROS) production through flow cytometry and immunofluorescence techniques. Furthermore, alterations in associated inflammatory factors and cytokines were quantified using real-time quantitative PCR with fluorescence detection.

RESULTS

We observed up-regulation of cGAS and STING expressions in the bladder tissue of rats in the KET group, stimulation with KET also led to increased cGAS and STING levels in SV-HUC-1 cells. Notably, the knockdown of STING inhibited the nuclear translocation of NF-κB p65 and IRF3, resulting in a decrease in the expression of inflammatory cytokines, including IL-6, IL-8, and CXCL10. Additionally, KET induced damage to the mitochondria of SV-HUC-1 cells, facilitating the release of mtDNA into the cytoplasm. This significant depletion of mtDNA inhibited the activation of cGAS-STING pathway, subsequently affecting the expression of NF-κB p65 and IRF3. Importantly, the reintroduction of mtDNA after STING knockdown partially restored the inflammatory response.

CONCLUSION

Our findings confirmed the activation of the cGAS-STING pathway in KC rats and revealed mitochondrial damage in vitro. These results highlight the involvement of the cGAS-STING pathway in the pathogenesis of KC, suggesting its potential as a therapeutic target for intervention.

Additively Manufactured Biodegradable Zn-Based Porous Scaffolds to Suppress Osteosarcoma and Promote Osteogenesis

Postoperative therapies for osteosarcoma present substantial challenges due to tumor recurrence and extensive bone defects. To tackle these challenges, laser powder bed fusion is utilized to fabricate biodegradable Zn-Li porous scaffolds that supress tumors and promote osteogenesis. After the structure design and composition selection, the Zn-0.8Li porous scaffold with Gyroid unit optimally balances the co-release of Zn2+ and Li+ during degradation, resulting in favorable antitumor and osteogenic effects. In vitro, the Zn-0.8Li scaffold significantly inhibits osteosarcoma progression by suppressing tumor cell proliferation, promoting apoptosis, alleviating migration, and simultaneously promotes osteogenic differentiation through the enhanced expression of osteogenic markers. In vivo, the Zn-0.8Li scaffold inhibits the malignant osteosarcoma behavior and facilitates bone regeneration in areas with bone defects. Transcriptomic analysis further reveals that the simultaneous release of Zn2+ and Li+ from the biodegradable Zn-0.8Li scaffold contributes to anti-osteosarcoma activity by downregulating PI3K/Akt signaling pathways. Taken together, the Zn-0.8Li porous scaffold fabricated using laser powder bed fusion with enhanced antitumor and osteogenic properties is a promising alternative for the postoperative management of osteosarcoma.

BAX pores facilitate mitochondrial DNA release in wasp sting-induced acute kidney injury

The role of B-cell lymphoma 2 (BCL2)-associated X (BAX) macropores in the leakage of mitochondrial DNA (mtDNA) and their impact on acute kidney injury (AKI) has recently been brought to the focus of researchers. This study aimed to explore the relationship between mtDNA leakage and BAX macropores during wasp sting-induced AKI. BAX mitochondrial translocation and macropores opening increased in both in vivo and in vitro models of wasp sting-induced AKI. In a mouse model, BAX inhibition dramatically attenuated mitochondrial impairment, cytoplasmic release of mtDNA, and suppressed activation of the mtDNA-cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. This attenuation improved kidney function, reduced inflammatory response, and decreased apoptosis in mouse models. Furthermore, in cultured human proximal tubular epithelial cells (HK-2) treated with myoglobin and subjected to BAX knockdown, quantitative real-time polymerase chain reaction (PCR) directly demonstrated decreased mtDNA release into the cytoplasm. Consistent with in vivo results, downregulation of BAX expression in vitro ameliorated mitochondrial damage and attenuated subsequent inflammation and apoptosis caused by the activation of the mtDNA-cGAS-STING signaling pathway. Our findings revealed that mtDNA is released into the cytoplasm through BAX macropores in wasp sting-induced AKI, which provided an important novel perspective for understanding wasp sting-induced AKI and is conducive for identifying novel therapeutic targets and strategies.

Reserpine alleviates cisplatin-induced acute kidney injury via anti-ferroptosis and cGAS/STING pathway

Cisplatin plays a pivotal role in the chemotherapy treatment of various cancers, but its use is often limited due to its nephrotoxic side effects. Identifying compounds that can mitigate cisplatin-induced nephrotoxicity is therefore of great importance. This study focused on evaluating the protective effects of reserpine against cisplatin-induced acute kidney injury. Reserpine was found to significantly safeguard against kidney damage caused by cisplatin, as indicated by the decreased levels of serum creatinine, blood urea nitrogen, and lactate dehydrogenase induced by cisplatin. Moreover, reserpine improved kidney histology damage caused by cisplatin treatment, with hematoxylin-eosin and periodic acid-Schiff staining revealing notable recovery from renal injury. Mechanistically, reserpine mitigated oxidative stress triggered by cisplatin and exhibits the ability to inhibit ferroptosis both in vivo and in vitro. Additionally, reserpine blocked the activation of the cGAS/STING signaling pathway and the subsequent expression of inflammatory genes, thus reducing inflammation-driven kidney damage. In summary, the findings suggest that reserpine offers a promising new strategy for preventing nephrotoxicity induced by cisplatin.

Eicosatrienoic acid enhances the quality of in vitro matured porcine oocytes by reducing PRKN-mediated ubiquitination of CISD2

Oocytes and early embryos are exposed to many uncontrollable factors that trigger endoplasmic reticulum (ER) stress during in vitro culture. Prevention of ER stress is an effective way to improve the oocyte maturation rate and oocyte quality. Increasing evidence suggests that dietary intake of sufficient n-3 polyunsaturated fatty acids (PUFAs) is associated with health benefits, particularly in the domain of female reproductive health. We found that supplementation of eicosatrienoic acid (ETA) during in vitro maturation (IVM) of oocyte significantly downregulated ER stress-related genes. Mitochondria-associated membranes (MAMs) are communications areas between the ER and mitochondria. Inositol 1,4,5-trisphosphate receptor (IP3R) is a key calcium channels in MAMs and, participates in the regulation of many cellular functions. Notably, the MAM area was significantly decreased in ETA-treated oocytes. CDGSH iron sulfur domain 2 (CISD2) is presents in MAMs, but its role in oocytes is unknown. ETA treatment significantly increased CISD2 expression, and siRNA-mediated knockdown of CISD2 blocked the inhibitory effect of ETA on IP3R. Transcriptomic sequencing and immunoprecipitation experiments showed that ETA treatment significantly decreased expression of the E3 ubiquitin ligase PRKN. PRKN induced ubiquitination and degradation of CISD2, indicating that the PRKN-mediated ubiquitin-proteasome system regulates CISD2. In conclusion, our study reveals the mechanism by which ETA supplementation during IVM alleviates mitochondrial calcium overload under ER stress conditions by decreasing PRKN-mediated ubiquitination of CISD2 and facilitating inhibition of IP3R by CISD2/BCL-2. This improves oocyte quality and subsequent embryo developmental competence prior to implantation.

A lipid signature of BAK-driven apoptotic pore formation

Apoptotic cell death is regulated by the BCL-2 protein family, with clusters of BAK or BAX homodimers driving pore formation in the mitochondrial outer membrane via a poorly understood process. There is growing evidence that, in addition to BAK and BAX, lipids play an important role in pore formation. Towards a better understanding of the lipidic drivers of apoptotic pore formation in isolated mitochondria, two complementary approaches were taken. Firstly, the lipids released during BAK-mediated pore formation were measured with targeted lipidomics, revealing enrichment of long chain polyunsaturated lysophospholipids (LPLs) in the released fraction. In contrast, the BAK protein was not released suggesting that BAK and LPLs locate to distinct microdomains. Secondly, added cholesterol not only prevented pore formation but prevented the clustering of BAK homodimers. Our data lead us to a model in which BAK clustering triggers formation of a separate microdomain rich in LPLs that can progress to lipid shedding and the opening of a lipid-lined pore. Pore stabilisation and growth may be due to BAK dimers then moving to the pore edge. Our BAK-lipid microdomain model supports the heterogeneity of BAK assemblies, and the observed lipid-release signature gives new insight into the genesis of the apoptotic pore.

Analysis of cytosolic mtDNA release during Staphylococcus aureus infection

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the principal human pathogens, causing severe infections in skin wounds. MRSA infection triggers a cell response mainly by mitochondrial-mediated pathway, resulting in mitochondrial outer membrane permeabilization, extrusion of the mitochondrial inner membrane into the cytoplasm, and then spillage of mitochondrial DNA (mtDNA) into the cytoplasm. The cell recognizes the discharged cytosolic mtDNA (cmtDNA) as "not-itself" because of mtDNA properties and triggers cascade events, such as the activation of inflammasomes. Here, we detail a method to detect and measure the mtDNA release into the cytoplasm in immortalized keratinocytes (HaCaT cells), after the infection with MRSA at different time points after the infection.

Transcriptomics reveals the mechanism of terbuthylazine-induced nephrotoxicity in chickens: Insights from AMPK/p53-mediated apoptosis perspective

As a commonly used pesticide, the widespread use of terbuthylazine (TBA) may cause toxic effects in animals and human. However, the nephrotoxicity induced by TBA is unclear. Here, we explored the mechanism of TBA-induced nephrotoxicity through transcriptomics and molecular biology techniques in broilers. Pathologic analysis showed that TBA could cause renal cell vacuolation and fibrosis in broilers. Additionally, transcriptomic analysis showed that TBA can cause significant changes in the expression of some apoptosis-related genes, and GO and KEGG analysis also found that TBA can significantly change the functions of apoptosis pathway and AMPK signaling pathway in kidney. Subsequently, the protein expression levels of Bax, Bak-1, FADD, and cleaved Caspase-3/Caspase-3 were elevated significantly and the number of TUNEL-positive cells was increased markedly in kidney under TBA exposure. Meanwhile, we also found that TBA could activate AMPK/p53 pathway, as evidenced by the upregulated levels of AMPKα1 phosphorylation and protein expression of p53. Therefore, our results suggested that TBA could induce apoptosis via AMPK/p53 pathway in kidney. These findings identified the nephrotoxic mechanism of TBA through transcriptomics, providing a new insight into TBA toxicology.

Inhibition of mitochondrial over-division by (+)-14,15-Dehydrovincamine attenuates cisplatin-induced acute kidney injury via the JNK/Mff pathway

Cisplatin-induced acute kidney injury (AKI) is characterized by mitochondrial damage and apoptosis, and safe and effective therapeutic agents are urgently needed. Renal tubular epithelial cells, the main site of AKI, are enriched with a large number of mitochondria, which are crucial for the progression of AKI with an impaired energy supply. Vincamine has anti-inflammatory and antioxidant effects in mouse AKI models. As a natural compound derived from Tabernaemontana pandacaqui, (+)-14, 15-Dehydrovincamine and Vincamine differ in structure by only one double bond, and the role and exact mechanism of (+)-14, 15-Dehydrovincamine remains to be elucidated in AKI. The present study demonstrated that (+)-14,15-Dehydrovincamine significantly ameliorated mitochondrial dysfunction and maintained mitochondrial homeostasis in a cisplatin-induced AKI model. Furthermore, (+)-14,15-Dehydrovincamine ameliorates cytochrome C-dependent apoptosis in renal tubular epithelial cells. c-Jun NH2-terminal kinase (JNK) was identified as a potential target protein of (+)-14,15-Dehydrovincamine attenuating AKI by network pharmacological analysis. (+)-14,15-Dehydrovincamine inhibited cisplatin-induced JNK activation, mitochondrial fission factor (Mff) phosphorylation, and dynamin-related protein 1 (Drp1) translocation to the mitochondria in renal tubular epithelial cells. Meanwhile, the JNK activator anisomycin restored Mff phosphorylation and Drp1 translocation, counteracting the protective effect of (+)-14,15-Dehydrovincamine on mitochondrial dysfunction in cisplatin-induced TECs injury. In conclusion, (+)-14,15-Dehydrovincamine reduced mitochondrial fission, maintained mitochondrial homeostasis, and attenuated apoptosis by inhibiting the JNK/Mff/Drp1 pathway, which in turn ameliorated cisplatin-induced AKI.

The emerging role of mtDNA release in sepsis: Current evidence and potential therapeutic targets

Sepsis is a systemic inflammatory reaction caused by infection, and severe sepsis can develop into septic shock, eventually leading to multiorgan dysfunction and even death. In recent years, studies have shown that mitochondrial damage is closely related to the occurrence and development of sepsis. Recent years have seen a surge in concern over mitochondrial DNA (mtDNA), as anomalies in this material can lead to cellular dysfunction, disruption of aerobic respiration, and even death of the cell. In this review, we discuss the latest findings on the mechanisms of mitochondrial damage and the molecular mechanisms controlling mitochondrial mtDNA release. We also explored the connection between mtDNA misplacement and inflammatory activation. Additionally, we propose potential therapeutic targets of mtDNA for sepsis treatment.

Japanese encephalitis virus infection induces mitochondrial-mediated apoptosis through the proapoptotic protein BAX

The Japanese encephalitis virus (JEV), a zoonotic flavivirus, is Asia's primary cause of viral encephalitis. JEV induces apoptosis in a variety of cells; however, the precise mechanisms underlying this apoptosis resulting from JEV infection remain to be elucidated. Our previous studies showed that the proapoptosis gene BAX may have a role in JEV proliferation. In this study, we constructed a PK-15 cell line (BAX.KO) with a knockout of the BAX gene using CRISPR/Cas9. The knockout of the BAX gene effectively inhibited the proliferation of JEV, resulting in a 39.9% decrease in viral protein levels, while BAX overexpression produced the opposite effect. We confirmed that JEV induces apoptosis of PK-15 using 4',6-diamidino-2-phenylindole (DAPI) staining and Annexin V-FITC/PI staining. Furthermore, we found that the phosphorylation of P53 and the expression levels of BAX, NOXA, PUMA, and cleaved-caspase-3/9 were significantly upregulated after JEV infection. Moreover, we found that JEV infection not only caused mitochondrial damage, the release of mitochondrial cytochrome C (Cyt C), and the downregulation of the apoptosis-inhibiting protein BCL-2 but also reduced the mitochondrial membrane potential (MOMP) and the accumulation of intracellular reactive oxygen species (ROS). These factors collectively encourage the activation of the mitochondrial apoptosis pathway. In contrast, BAX gene knockout significantly reduces the apoptotic changes caused by JEV infection. Treatment with the caspase3 inhibitor attenuated JEV-induced viral proliferation and release, leading to a decrease in viral protein levels of 46% in PK-15 cells and 30% in BAX.KO cells. In conclusion, this study clarified the molecular mechanisms of JEV-induced apoptosis and provided a theoretical basis for revealing the pathogenic mechanisms of JEV infection.

c-Jun N-terminal kinase 1/P53 signaling mediates intrinsic apoptosis of largemouth bass (Micropterus salmoides) hepatocytes under heat stress

The increasing frequency of high-temperature extremes threatens largemouth bass Micropterus salmoides, a significant fish for freshwater ecosystems and aquaculture. Our previous studies at the transcript level suggested that heat stress induces hepatic apoptosis in largemouth bass. In the current study, we sought to validate these findings and further investigate the role of the c-Jun N-terminal kinase (JNK)/P53 signaling in hepatic apoptosis under heat stress. First, heat treatments were conducted in vivo and in vitro under different temperatures: 28 °C, 32 °C, and 37 °C. In primary hepatocytes subjected to heat treatment, cell viability was evaluated via the Cell Counting Kit-8, while mitochondrial membrane potential and nuclear morphology were assessed through JC-1 and Hoechst 33258 staining, respectively. We observed reductions in both cell viability and mitochondrial membrane potential (ΔΨm), along with alterations in nuclear morphology, in primary hepatocytes exposed to heat stress at temperatures of 32 °C and 37 °C. Quantitative real-time PCR revealed significant alterations in the expression profiles of intrinsic apoptosis-related genes within liver tissues under heat stress. Immunohistochemistry analysis revealed that JNK1 signaling increased as the temperature increased, JNK2 expression increased only at 37 °C, and JNK3 expression did not change with temperature. We speculate that JNK1 and JNK2 have pro- and anti-apoptotic effects, respectively. Western blot analysis conducted on cultured hepatocytes further validated these findings. JNK inhibition reduced hepatocyte apoptosis, improved nuclear morphology, and maintained ΔΨm even after 37 °C treatment. These results not only confirm that heat stress led to intrinsic apoptosis of hepatocytes but also indicated that JNK1 could mediate P53 expression and activate caspase-dependent intrinsic apoptosis in largemouth bass hepatocytes under such conditions. This study illuminates the physiological responses of largemouth bass to acute heat stress, offering valuable insights into the potential impacts of climate change on freshwater fishes and the sustainability of aquaculture.

The minimal membrane requirements for BAX-induced pore opening upon exposure to oxidative stress

Perforation of the outer mitochondrial membrane triggered by BAX and facilitated by its main activator cBID is a fundamental process in cell apoptosis. Here, we employ a newly designed correlative approach based on a combination of a fluorescence cross correlation binding with a calcein permeabilization assay to understand the involvement of BAX in pore formation under oxidative stress conditions. To mimic the oxidative stress, we enriched liposomal membranes by phosphatidylcholines with truncated sn-2 acyl chains terminated by a carboxyl or aldehyde moiety. Our observations revealed that oxidative stress enhances proapoptotic conditions involving accelerated pore-opening kinetics. This enhancement is achieved through increased recruitment of BAX to the membrane and facilitation of BAX membrane insertion. Despite these effects, the fundamental mechanism of pore formation remained unchanged, suggesting an all-or-none mechanism. In line with this mechanism, we demonstrated that the minimal number of BAX molecules at the membrane necessary for pore formation remains constant regardless of BAX activation by cBID or the presence of oxidized lipids. Overall, our findings give a comprehensive picture of the molecular mechanisms underlying apoptotic pore formation and highlight the selective amplifying role of oxidized lipids in triggering formation of membrane pores.

Cytoplasmic DNA and AIM2 inflammasome in RA: where they come from and where they go?

Rheumatoid arthritis is a chronic autoimmune disease of undetermined etiology characterized by symmetric synovitis with predominantly destructive and multiple joint inflammation. Cytoplasmic DNA sensors that recognize protein molecules that are not themselves or abnormal dsDNA fragments play an integral role in the generation and perpetuation of autoimmune diseases by activating different signaling pathways and triggering innate immune signaling pathways and host defenses. Among them, melanoma deficiency factor 2 (AIM2) recognizes damaged DNA and double-stranded DNA and binds to them to further assemble inflammasome, initiating the innate immune response and participating in the pathophysiological process of rheumatoid arthritis. In this article, we review the research progress on the source of cytoplasmic DNA, the mechanism of assembly and activation of AIM2 inflammasome, and the related roles of other cytoplasmic DNA sensors in rheumatoid arthritis.

Mitochondrion-based organellar therapies for central nervous system diseases

As most traditional drugs used to treat central nervous system (CNS) diseases have a single therapeutic target, many of them cannot treat complex diseases or diseases whose mechanism is unknown and cannot effectively reverse the root changes underlying CNS diseases. This raises the question of whether multiple functional components are involved in the complex pathological processes of CNS diseases. Organelles are the core functional units of cells, and the replacement of damaged organelles with healthy organelles allows the multitargeted and integrated modulation of cellular functions. The development of therapies that target independent functional units in the cell, specifically, organelle-based therapies, is rapidly progressing. This article comprehensively discusses the pathogenesis of mitochondrial homeostasis disorders, which involve mitochondria, one of the most important organelles in CNS diseases, and the machanisms of mitochondrion-based therapies, as well as current preclinical and clinical studies on the efficacy of therapies targeting mitochondrial to treat CNS diseases, to provide evidence for use of organelle-based treatment strategies in the future.

The expression of VDACs and Bcl2 family genes in pituitary adenomas: clinical correlations and postsurgical outcomes

Introduction

Pituitary adenomas (PAs) are benign tumors with high prevalence and, occasionally, aggressive course. The tumorigenesis of these lesions is not completely understood at the molecular level. BAK1 and BAX proteins play fundamental roles in apoptosis and seem to interact with VDAC proteins, whose expressions have been markedly altered in cancer, impacting their prognosis.

Objective

to evaluate the gene expression of VDAC1, VDAC2, BAK1 and BAX and their association with clinical and imaging characteristics in PA.

Methods

Clinical-epidemiological data were collected from 117 tumor samples from patients affected by PA. Invasiveness was assessed by the Knosp scale. Gene expression was examined by real-time PCR. Relative expression analysis was performed by 2^(-DDCt) method.

Results

The sample was mainly composed of women (69/117 - 57.2%). Tumor subtypes observed were Non-Functioning (NF) (73/117 - 62.4%), Acromegaly (24/117 - 20.5%) and Cushing's Disease (CD) (20/117 - 17.1%). Compared to normal tissue, there was a significant reduction in VDAC1 expression in the Acromegaly (p=0.029) and NF (p=0.002) groups. BAX expression was lower in all groups (p <0.001; p=0.007; P =0.005). No difference was found in VDAC2 and BAK1 expression, compared to normal pituitary. Overexpression of VDAC2 occurred in PAs with post-surgical regrowth (p=0.042). A strongly negative correlation was observed in BAX and BAK1 expression in CD.

Conclusion

The results indicated that downregulations of VDAC1 and BAX may be related to resistance to apoptosis. In contrast, overexpression of VDAC2 in regrowing PAs suggests an antiapoptotic role for this gene. In summary, the genes evaluated might be involved in the biopathology of PAs.

Gasdermin D cysteine residues synergistically control its palmitoylation-mediated membrane targeting and assembly

Gasdermin D (GSDMD) executes the cell death program of pyroptosis by assembling into oligomers that permeabilize the plasma membrane. Here, by single-molecule imaging, we elucidate the yet unclear mechanism of Gasdermin D pore assembly and the role of cysteine residues in GSDMD oligomerization. We show that GSDMD preassembles at the membrane into dimeric and trimeric building blocks that can either be inserted into the membrane, or further assemble into higher-order oligomers prior to insertion into the membrane. The GSDMD residues Cys39, Cys57, and Cys192 are the only relevant cysteines involved in GSDMD oligomerization. S-palmitoylation of Cys192, combined with the presence of negatively-charged lipids, controls GSDMD membrane targeting. Simultaneous Cys39/57/192-to-alanine (Ala) mutations, but not Ala mutations of Cys192 or the Cys39/57 pair individually, completely abolish GSDMD insertion into artificial membranes as well as into the plasma membrane. Finally, either Cys192 or the Cys39/Cys57 pair are sufficient to enable formation of GSDMD dimers/trimers, but they are all required for functional higher-order oligomer formation. Overall, our study unveils a cooperative role of Cys192 palmitoylation-mediated membrane binding and Cys39/57/192-mediated oligomerization in GSDMD pore assembly. This study supports a model in which Gasdermin D oligomerization relies on a two-step mechanism mediated by specific cysteine residues.

Permeabilization of the outer mitochondrial membrane: Mechanisms and consequences

Permeabilization of the outer mitochondrial membrane is а physiological process that can allow certain molecules to pass through it, such as low molecular weight solutes required for cellular respiration. This process is also important for the development of various modes of cell death. Depending on the severity of this process, cells can die by autophagy, apoptosis, or necrosis/necroptosis. Distinct types of pores can be opened at the outer mitochondrial membrane depending on physiological or pathological stimuli, and different mechanisms can be activated in order to open these pores. In this comprehensive review, all these types of permeabilization, the mechanisms of their activation, and their role in various diseases are discussed.

The antioxidant and selective apoptotic activities of modified auraptene-loaded graphene quantum dot nanoparticles (M-AGQD-NP)

BACKGROUND

Pancreatic and Gastric cancers are very aggressive and deadly types of cancer that require effective treatment strategies to stop their progression. Nano-drug delivery systems, like those using Auraptene-loaded GQD nanoparticles, play a crucial role in addressing this need by delivering targeted and controlled treatments to cancer cells, making treatment more effective, and reducing side effects. The study focused on investigating the effects of Auraptene, an efficient anticancer compound when loaded into Graphene Quantum Dots (GQDs) on types of human cancer cells.

METHODS

To create auraptene-loaded graphene quantum dot nanoparticles (AGQD-NP) (Unmodified and modified types) a combination of hydrothermal and high-energy homogenization methods was used. The nanoparticles were characterized by conducting DLS (Dynamic light scattering), FTIR (Fourier-transform infrared spectroscopy), FESEM (Field Emission Scanning Electron microscopy), and zeta potential analysis. bioactivity of AGQD-NP was assessed through tests, including antioxidant capacity measured by ABTS and DPPH scavenging abilities well as cytotoxicity tested using MTT assay on both human cancer cell lines and normal human vascular endothelial cells.

RESULTS

The modified AGQD-NP (M-AGQD-NP) demonstrated antioxidant properties by neutralizing free radicals. They also displayed selective toxicity, towards human gastric adenocarcinoma cell-line (AGS) and human pancreatic adenocarcinoma (PANC) cancer cells with IC50 values recorded at 78.8 µg/mL and 89.72 µg/mL respectively. The specific targeting of gastric cancer cells was evident from the differing IC50 values compared to the Human breast adenocarcinoma cell line (MCF-7), Human hepatocellular carcinoma cell line (Hella), and normal vascular endothelial cells (Huvec). Additionally, the induced apoptotic death, in the human pancreatic adenocarcinoma (PANC) cancer cells was confirmed through AO/PI staining and Annexin-based flow cytometry revealing increased expression levels of P53, Caspase3, BAX, and Caspase8.

CONCLUSION

In summary, the M-AGQD-NP have shown encouraging effects displaying antioxidant capabilities and a specific focus, on pancreatic and gastric cancer cells. These findings indicate uses for AGQD-NP as an efficient apoptosis inducer in cancer treatment. Additional In-vivo researches are required to validate their effectiveness, in living organisms.

Targeting protein condensation in cGAS-STING signaling pathway

The cGAS-STING signaling pathway plays a pivotal role in sensing cytosolic DNA and initiating innate immune responses against various threats, with disruptions in this pathway being associated with numerous immune-related disorders. Therefore, precise regulation of the cGAS-STING signaling is crucial to ensure appropriate immune responses. Recent research, including ours, underscores the importance of protein condensation in driving the activation and maintenance of innate immune signaling within the cGAS-STING pathway. Consequently, targeting condensation processes in this pathway presents a promising approach for modulating the cGAS-STING signaling and potentially managing associated disorders. In this review, we provide an overview of recent studies elucidating the role and regulatory mechanism of protein condensation in the cGAS-STING signaling pathway while emphasizing its pathological implications. Additionally, we explore the potential of understanding and manipulating condensation dynamics to develop novel strategies for mitigating cGAS-STING-related disorders in the future.

Trafficking of mitochondrial double-stranded RNA from mitochondria to the cytosol

In addition to mitochondrial DNA, mitochondrial double-stranded RNA (mtdsRNA) is exported from mitochondria. However, specific channels for RNA transport have not been demonstrated. Here, we begin to characterize channel candidates for mtdsRNA export from the mitochondrial matrix to the cytosol. Down-regulation of SUV3 resulted in the accumulation of mtdsRNAs in the matrix, whereas down-regulation of PNPase resulted in the export of mtdsRNAs to the cytosol. Targeting experiments show that PNPase functions in both the intermembrane space and matrix. Strand-specific sequencing of the double-stranded RNA confirms the mitochondrial origin. Inhibiting or down-regulating outer membrane proteins VDAC1/2 and BAK/BAX or inner membrane proteins PHB1/2 strongly attenuated the export of mtdsRNAs to the cytosol. The cytosolic mtdsRNAs subsequently localized to large granules containing the stress protein TIA-1 and activated the type 1 interferon stress response pathway. Abundant mtdsRNAs were detected in a subset of non-small-cell lung cancer cell lines that were glycolytic, indicating relevance in cancer biology. Thus, we propose that mtdsRNA is a new damage-associated molecular pattern that is exported from mitochondria in a regulated manner.

Mitochondria and cell death

Mitochondria are cellular factories for energy production, calcium homeostasis and iron metabolism, but they also have an unequivocal and central role in intrinsic apoptosis through the release of cytochrome c. While the subsequent activation of proteolytic caspases ensures that cell death proceeds in the absence of collateral inflammation, other phlogistic cell death pathways have been implicated in using, or engaging, mitochondria. Here we discuss the emerging complexities of intrinsic apoptosis controlled by the BCL-2 family of proteins. We highlight the emerging theory that non-lethal mitochondrial apoptotic signalling has diverse biological roles that impact cancer, innate immunity and ageing. Finally, we delineate the role of mitochondria in other forms of cell death, such as pyroptosis, ferroptosis and necroptosis, and discuss mitochondria as central hubs for the intersection and coordination of cell death signalling pathways, underscoring their potential for therapeutic manipulation.

Nemo mRNA vaccination improves airway barrier function in mice with airway allergy

Epithelial barrier dysfunction plays an important role in the pathogenesis of Th2 bias. The mechanism requires further clarification. NEMO is associated with regulating apoptotic activities in the cell. The purpose of this study is to investigate the role of insufficient Nemo signals in developing Th2 bias in the respiratory tract. Nemof/fEpcam-Cre mice (A mouse strain carrying NEMO-deficient epithelial cells. NemoKO mice, in short) was generated. An airway Th2 bias mouse model was established with the ovalbumin/alum protocol. The NemoKO mice exhibited spontaneous airway Th2 bias. Respiratory tract epithelial barrier integrity was compromised in NemoKO mice. Apoptosis was found in approximately 10% of the epithelial cells of the respiratory tract in NemoKO mice. The reconstruction of the Nemo expression restored homeostasis within the epithelial barrier of the airways. Restoration of Nemo gene expression in epithelial cells by Nemo mRNA vaccination alleviated Th2 bias in mice with airway allergy. To sum up, NEMO plays an important role in maintaining the integrity of the epithelial barrier in the respiratory tract. Administration of NEMO mRNA vaccines can restore epithelial barrier functions and alleviate Th2 bias in the airways.

Zinc ions regulate mitochondrial quality control in neurons under oxidative stress and reduce PANoptosis in spinal cord injury models via the Lgals3-Bax pathway

Spinal cord injury is a serious traumatic nervous system disorder characterized by extensive neuronal apoptosis. Oxidative stress, a key factor in neuronal apoptosis, leads to the accumulation of reactive oxygen species, making mitochondrial quality control within cells crucial. Previous studies have demonstrated zinc's anti-inflammatory and anti-apoptotic properties in protecting mitochondria during spinal cord injury treatment, yet the precise mechanisms remain elusive. Single-cell sequencing analysis has identified Lgals3 and Bax as core genes in apoptosis. This study aimed to investigate whether zinc ions protect intracellular mitochondria by inhibiting the apoptotic proteins Lgals3 and Bax. We elucidated zinc ions' key role in mitigating mitochondrial quality control dysfunction triggered by oxidative stress and confirmed this was achieved by targeting the Lgals3-Bax pathway. Zinc's inhibitory effect on this pathway not only preserved mitochondrial integrity but also significantly reduced PANoptosis after spinal cord injury. Under oxidative stress, zinc ion regulation of mitochondrial quality control reveals an organelle-targeted therapeutic strategy, offering a novel approach for more precise treatment of spinal cord injury.