A Chemical Inhibitor of DRP1 Uncouples Mitochondrial Fission and Apoptosis

OrgaMeas: A pipeline that integrates all the processes of organelle image analysis

Although image analysis has emerged as a key technology in the study of organelle dynamics, the commonly used image-processing methods, such as threshold-based segmentation and manual setting of regions of interests (ROIs), are error-prone and laborious. Here, we present a highly accurate high-throughput image analysis pipeline called OrgaMeas for measuring the morphology and dynamics of organelles. This pipeline mainly consists of two deep learning-based tools: OrgaSegNet and DIC2Cells. OrgaSegNet quantifies many aspects of different organelles by precisely segmenting them. To further process the segmented data at a single-cell level, DIC2Cells automates ROI settings through accurate segmentation of individual cells in differential interference contrast (DIC) images. This pipeline was designed to be low cost and require less coding, to provide an easy-to-use platform. Thus, we believe that OrgaMeas has potential to be readily applied to basic biomedical research, and hopefully to other practical uses such as drug discovery.

Powering immunity: mitochondrial dynamics in natural killer cells

Natural killer (NK) cells are innate lymphocytes that are crucial for eliminating malignant and infected cells, and have significant therapeutic potential against cancer and viral infections. However, their functionality is often impaired under pathological conditions. Emerging evidence identifies mitochondria as key regulators of NK cell metabolism, fitness, and fate. This review examines how mitochondrial dysfunction impacts on NK cell activity in cancer, viral infections, and inflammatory disorders. We discuss strategies to target mitochondrial architecture, dynamics, and function as potential therapies to restore NK cell fitness. Finally, we highlight unanswered questions and future directions to better understand mitochondrial regulation in NK cells and its implications for therapeutic development.

PRKAA2-mediated mitophagy regulates oxygen consumption in yak renal tubular epithelial cells under chronic hypoxia

Hypoxic environments are significant factors in the induction of various kidney diseases and are closely associated with high oxygen consumption in the kidneys. Yaks live at high altitude for a long time, exhibit a unique ability to regulate kidney oxygen consumption, protecting them from hypoxia-induced damage. However, the mechanisms underlying the regulation of oxygen consumption in yak kidneys under hypoxic conditions remain unclear. To explore this hypoxia adaptation mechanism in yak kidneys, this study analyzed the oxygen consumption rate (OCR) of renal tubular epithelial cells (RTECs) under hypoxia. We found that the OCR and apoptosis rates of RTECs under chronic hypoxia (> 24 h) were lower than those under acute hypoxia (≤ 24 h). However, when oxygen consumption was promoted under chronic hypoxia, the apoptosis rate increased, indicating that reducing the cellular OCR is crucial for maintaining RTECs activity under hypoxia. High-throughput sequencing results showed that the mitophagy pathway is likely a key mechanism for inhibiting OCR of yak RTECs, with protein kinase AMP-activated catalytic subunit alpha 2 (PRKAA2) playing a significant role in this process. Further studies demonstrated that chronic hypoxia activates the mitophagy pathway, which inhibits oxidative phosphorylation (OXPHOS) while increasing glycolytic flux in yak RTECs. Conversely, when the mitophagy pathway was inhibited, there was an increase in the activity of OXPHOS enzymes and OCR. To further explore the role of PRKAA2 in the mitophagy pathway, we inhibited PRKAA2 expression under chronic hypoxia. Results showed that the downregulation of PRKAA2 decreased the expression of mitophagy-related proteins, such as p-FUNDC1/FUNDC1, LC3-II/LC3-I, BNIP3 and ULK1 while upregulating P62 expression. Additionally, there was an increase in the enzyme activities of Complex II, Complex IV, PDH, and SDH, which further promoted oxygen consumption in RTECs. These findings suggest that PRKAA2 mediated mitophagy under chronic hypoxia is crucial mechanism for reducing oxygen consumption in yak RTECs.

Apoptosis, Mitochondrial Autophagy, Fission, and Fusion Maintain Mitochondrial Homeostasis in Mouse Liver Under Tail Suspension Conditions

Microgravity can induce alterations in liver morphology, structure, and function, with mitochondria playing an important role in these changes. Tail suspension (TS) is a well-established model for simulating the effects of microgravity on muscles and bones, but its impact on liver function remains unclear. In the current study, we explored the regulatory mechanisms of apoptosis, autophagy, fission, and fusion in maintaining liver mitochondrial homeostasis in mice subjected to TS for 2 or 4 weeks (TS2 and TS4). The results showed the following: (1) No significant differences were observed in nuclear ultrastructure or DNA fragmentation between the control and TS-treated groups. (2) No significant differences were detected in the mitochondrial area ratio among the three groups. (3) Cysteine aspartic acid-specific protease 3 (Caspase3) activity and the Bcl-2-associated X protein (bax)/B-cell lymphoma-2 (bcl2) ratio were not higher in the TS2 and TS4 groups compared to the control group. (4) dynamin-related protein 1 (DRP1) protein expression was increased, while mitochondrial fission factor (MFF) protein levels were decreased in the TS2 and TS4 groups compared to the control, suggesting stable mitochondrial fission. (5) No significant differences were observed in the optic atrophy 1 (OPA1), mitofusin 1 and 2 (MFN1 and MFN2) protein expression levels across the three groups. (6) Mitochondrial autophagy vesicles were present in the TS2 and TS4 groups, with a significant increase in Parkin phosphorylation corresponding to the duration of the TS treatment. (7) ATP synthase and citrate synthase activities were significantly elevated in the TS2 group compared to the control group but were significantly reduced in the TS4 group compared to the TS2 group. In summary, the coordinated regulation of apoptosis, mitochondrial fission and fusion, and particularly mitochondrial autophagy preserved mitochondrial morphology and contributed to the restoration of the activities of these two key mitochondrial enzymes, thereby maintaining liver mitochondrial homeostasis in mice under TS conditions.

Infection-induced peripheral mitochondria fission drives ER encapsulations and inter-mitochondria contacts that rescue bioenergetics

The dynamic regulation of mitochondria shape via fission and fusion is critical for cellular responses to stimuli. In homeostatic cells, two modes of mitochondrial fission, midzone and peripheral, provide a decision fork between either proliferation or clearance of mitochondria. However, the relationship between specific mitochondria shapes and functions remains unclear in many biological contexts. While commonly associated with decreased bioenergetics, fragmented mitochondria paradoxically exhibit elevated respiration in several disease states, including infection with the prevalent pathogen human cytomegalovirus (HCMV) and metastatic melanoma. Here, incorporating super-resolution microscopy with mass spectrometry and metabolic assays, we use HCMV infection to establish a molecular mechanism for maintaining respiration within a fragmented mitochondria population. We establish that HCMV induces fragmentation through peripheral mitochondrial fission coupled with suppression of mitochondria fusion. Unlike uninfected cells, the progeny of peripheral fission enter mitochondria-ER encapsulations (MENCs) where they are protected from degradation and bioenergetically stabilized during infection. MENCs also stabilize pro-viral inter-mitochondria contacts (IMCs), which electrochemically link mitochondria and promote respiration. Demonstrating a broader relevance, we show that the fragmented mitochondria within metastatic melanoma cells also form MENCs. Our findings establish a mechanism where mitochondria fragmentation can promote increased respiration, a feature relevant in the context of human diseases.

Propofol-induced hippocampal Neurotoxicity: A mitochondrial perspective

Propofol is a frequently used anesthetic. It can induce neurodegeneration and inhibit neurogenesis in the hippocampus. This effect may be temporary. It can, however, become permanent in vulnerable populations, such as the elderly, who are more susceptible to Alzheimer's disease, and neonates and children, whose brains are still developing and require neurogenesis. Current clinical practice strategies have failed to provide an effective solution to this problem. In addition, the molecular mechanism of this toxicity is not fully understood. Recent advances in molecular research have revealed that apoptosis, in close association with mitochondria, is a crucial mechanism through which propofol contributes to hippocampal toxicity. Preventing the toxicity of propofol on the hippocampus has shown promise in in-vivo, in-vitro, and to a lesser extent human studies. This study seeks to provide a comprehensive literature review of the effects of propofol toxicity on the hippocampus via mitochondria and to suggest translational suggestions based on these molecular results.

Targeting Mitochondrial Dynamics during Lower-Limb Ischemia Reperfusion in Young and Old Mice: Effect of Mitochondrial Fission Inhibitor-1 (mDivi-1)

Peripheral arterial disease (PAD) strikes more than 200 million people worldwide and has a severe prognosis by potentially leading to limb amputation and/or death, particularly in older patients. Skeletal muscle mitochondrial dysfunctions and oxidative stress play major roles in this disease in relation with ischemia-reperfusion (IR) cycles. Mitochondrial dynamics through impairment of fission-fusion balance may contribute to skeletal muscle pathophysiology, but no data were reported in the setting of lower-limb IR despite the need for new therapeutic options. We, therefore, investigated the potential protective effect of mitochondrial division inhibitor-1 (mDivi-1; 50 mg/kg) in young (23 weeks) and old (83 weeks) mice submitted to two-hour ischemia followed by two-hour reperfusion on systemic lactate, muscle mitochondrial respiration and calcium retention capacity, and on transcripts specific for oxidative stress and mitochondrial dynamics. At the systemic levels, an IR-related increase in circulating lactate was still major despite mDivi-1 use (+305.9% p < 0.0001, and +269.4% p < 0.0001 in young and old mice, respectively). Further, IR-induced skeletal muscle mitochondrial dysfunctions (more severely impaired mitochondrial respiration in old mice (OXPHOS CI state, -68.2% p < 0.0001 and -84.9% p < 0.0001 in 23- and 83-week mice) and reduced calcium retention capacity (-46.1% p < 0.001 and -48.2% p = 0.09, respectively) were not corrected by mDivi-1 preconditioning, whatever the age. Further, mDivi-1 treatment did not oppose superoxide anion production (+71.4% p < 0.0001 and +37.5% p < 0.05, respectively). At the transcript level, markers of antioxidant enzymes (SOD 1, SOD 2, catalase, and GPx) and fission markers (Drp1, Fis) remained unchanged or tended to be decreased in the ischemic leg. Fusion markers such as mitofusin 1 or 2 decreased significantly after IR in both groups. In conclusion, aging enhanced the deleterious effects or IR on muscle mitochondrial respiration, and in this setting of lower-limb IR, mDivi-1 failed to protect the skeletal muscle both in young and old mice.

MiR-181a protects the heart against myocardial infarction by regulating mitochondrial fission via targeting programmed cell death protein 4

Worldwide, myocardial infarction (MI) is the leading cause of death and disability-adjusted life years lost. Recent researches explored new methods of detecting biomarkers that can predict the risk of developing myocardial infarction, which includes identifying genetic markers associated with increased risk. We induced myocardial infarction in mice by occluding the left anterior descending coronary artery and performed TTC staining to assess cell death. Next, we performed ChIP assays to measure the enrichment of histone modifications at the promoter regions of key genes involved in mitochondrial fission. We used qPCR and western blot to measure expression levels of relative apoptotic indicators. We report that miR-181a inhibits myocardial ischemia-induced apoptosis and preserves left ventricular function after MI. We show that programmed cell death protein 4 (PDCD4) is the target gene involved in miR-181a-mediated anti-ischemic injury, which enhanced BID recruitment to the mitochondria. In addition, we discovered that p53 inhibits the expression of miR-181a via transcriptional regulation. Here, we discovered for the first time a mitochondrial fission and apoptosis pathway which is controlled by miR-181a and involves PDCD4 and BID. This pathway may be controlled by p53 transcriptionally, and we presume that miR-181a may lead to the discovery of new therapeutic and preventive targets for ischemic heart diseases.

Phosphorylation of INF2 by AMPK promotes mitochondrial fission and oncogenic function in endometrial cancer

Mitochondria are highly dynamic organelles capable of altering their sizes and shapes to maintain metabolic balance through coordinated fission and fusion processes. In various cancer types, mitochondrial hyperfragmentation has been frequently observed, contributing to the progression of cancer toward metastasis. Inverted formin 2 (INF2), which resides in the endoplasmic reticulum (ER), has been found to accelerate actin polymerization and drive mitochondrial fission. In this study, we demonstrate that INF2 expression is significantly upregulated in endometrial cancer (EC) and is associated with a poor prognosis in EC patients. INF2 promotes anchorage-dependent and independent EC cell growth in part by facilitating mitochondrial fission. Furthermore, in conditions of energy stress, AMP-activated protein kinase (AMPK) phosphorylates INF2 at Ser1077, leading to increased localization of INF2 to the ER and enhanced recruitment of the dynamin-related protein 1 (DRP1) to mitochondria. This AMPK-mediated phosphorylation of INF2 at Ser1077 facilitates mitochondrial division and promotes EC cell growth. Pathological examination using immunohistochemical analyses revealed a positive correlation between AMPK activity and phosphorylated INF2 (Ser1077) in EC specimens. Collectively, our findings uncover novel molecular mechanisms involving the AMPK-INF2 axis, which regulates mitochondrial dynamics and malignant cell growth in EC.

Zearalenone promotes porcine ESCs apoptosis by enhancing Drp1-mediated mitochondrial fragmentation and activating the JNK pathway

Zearalenone (ZEA) is widely present in food and feed, and pigs are susceptible to its effects. This study explored the underlying function of ZEA-induced apoptosis in porcine endometrial stromal cells (ESCs) through activation of the JNK signaling pathway and mitochondrial division. This study utilized ESCs to explore the impact of exposure to ZEA. A mitochondrial division inhibitor (Mdivi) was also included as a reference. The results indicated a gradual decrease in cell viability with increasing ZEA concentration. In addition, ZEA can modify the growth status of porcine ESCs, disrupt their ultrastructure, and lead to apoptosis of porcine ESCs via the mitochondrial division pathway and JNK signaling pathway. In summary, our study found the critical targets of ZEA infected with pig ESCs, which provided a conceptual foundation to prevent and control ZEA.

High Yield of Functional Dopamine-like Neurons Obtained in NeuroForsk 2.0 Medium to Study Acute and Chronic Rotenone Effects on Oxidative Stress, Autophagy, and Apoptosis

Several efforts to develop new protocols to differentiate in in vitro human mesenchymal stromal cells (hMSCs) into dopamine (DA) neurons have been reported. We have formulated NeuroForsk 2.0 medium containing fibroblast growth factor type beta (FGFb), brain-derived neurotrophic factor (BDNF), melatonin, purmorphamine, and forskolin. We report for the first time that menstrual stromal cells (MenSCs) cultured in NeuroForsk 2.0 medium for 7 days transdifferentiated into DA-like neurons (DALNs) expressing specific DA lineage markers tyrosine hydroxylase-positive cells (TH+) and DA transporter-positive (DAT+) cells and were responsive to DA-induced transient Ca2+ influx. To test the usefulness of this medium, DALNs were exposed to rotenone (ROT), a naturally occurring organic neurotoxin used extensively to chemically induce an in vitro model of Parkinson's disease (PD), which is a movement disorder characterized by the specific loss of DA neurons. We wanted to determine whether ROT induces apoptotic cell death and autophagy pathway under acute or chronic conditions in DALNs. Here, we report that acute ROT exposure induced several molecular changes in DALNS. ROT induced a loss of mitochondrial membrane potential (ΔΨm), high expression of parkin (PRKN), and high colocalization of dynamin-related protein 1 (DRP1) with the mitochondrial translocase of the outer membrane of mitochondria 20 (TOMM20) protein. Acute ROT also induced the appearance of DJ-1Cys106-SO3, as evidenced by the generation of H2O2 and oxidative stress (OS) damage. Remarkably, ROT triggered the phosphorylation of leucine-rich repeat kinase 2 (LRRK2) at residue Ser935 and phosphorylation of α-Syn at residue Ser129, a pathological indicator. ROT induced the accumulation of lipidated microtubule-associated protein 1B-light chain 3 (LC3B), a highly specific marker of autophagosomes. Finally, ROT induced cleaved caspase 3 (CC3), a marker of activated caspase 3 (CASP3) in apoptotic DALNs compared to untreated DANLs. However, the chronic condition was better at inducing the accumulation of lysosomes than the acute condition. Importantly, the inhibitor of the LRRK2 kinase PF-06447475 (PF-475) almost completely blunted ROT-induced apoptosis and reduced ROT-induced accumulation of lysosomes in both acute and chronic conditions in DALNs. Our data suggest that LRRK2 kinase regulated both apoptotic cell death and autophagy in DALNs under OS. Given that defects in mitochondrial complex I activity are commonly observed in PD, ROT works well as a chemical model of PD in both acute and chronic conditions. Therefore, prevention and treatment therapy should be guided to relieve DALNs from mitochondrial damage and OS, two of the most important triggers in the apoptotic cell death of DALNs.

Functional annotation map of natural compounds in traditional Chinese medicines library: TCMs with myocardial protection as a case

The chemical complexity of traditional Chinese medicines (TCMs) makes the active and functional annotation of natural compounds challenging. Herein, we developed the TCMs-Compounds Functional Annotation platform (TCMs-CFA) for large-scale predicting active compounds with potential mechanisms from TCM complex system, without isolating and activity testing every single compound one by one. The platform was established based on the integration of TCMs knowledge base, chemome profiling, and high-content imaging. It mainly included: (1) selection of herbal drugs of target based on TCMs knowledge base; (2) chemome profiling of TCMs extract library by LC‒MS; (3) cytological profiling of TCMs extract library by high-content cell-based imaging; (4) active compounds discovery by combining each mass signal and multi-parametric cell phenotypes; (5) construction of functional annotation map for predicting the potential mechanisms of lead compounds. In this stud TCMs with myocardial protection were applied as a case study, and validated for the feasibility and utility of the platform. Seven frequently used herbal drugs (Ginseng, etc.) were screened from 100,000 TCMs formulas for myocardial protection and subsequently prepared as a library of 700 extracts. By using TCMs-CFA platform, 81 lead compounds, including 10 novel bioactive ones, were quickly identified by correlating 8089 mass signals with 170,100 cytological parameters from an extract library. The TCMs-CFA platform described a new evidence-led tool for the rapid discovery process by data mining strategies, which is valuable for novel lead compounds from TCMs. All computations are done through Python and are publicly available on GitHub.

Unveiling the potential of mitochondrial dynamics as a therapeutic strategy for acute kidney injury

Acute Kidney Injury (AKI), a critical clinical syndrome, has been strongly linked to mitochondrial malfunction. Mitochondria, vital cellular organelles, play a key role in regulating cellular energy metabolism and ensuring cell survival. Impaired mitochondrial function in AKI leads to decreased energy generation, elevated oxidative stress, and the initiation of inflammatory cascades, resulting in renal tissue damage and functional impairment. Therefore, mitochondria have gained significant research attention as a potential therapeutic target for AKI. Mitochondrial dynamics, which encompass the adaptive shifts of mitochondria within cellular environments, exert significant influence on mitochondrial function. Modulating these dynamics, such as promoting mitochondrial fusion and inhibiting mitochondrial division, offers opportunities to mitigate renal injury in AKI. Consequently, elucidating the mechanisms underlying mitochondrial dynamics has gained considerable importance, providing valuable insights into mitochondrial regulation and facilitating the development of innovative therapeutic approaches for AKI. This comprehensive review aims to highlight the latest advancements in mitochondrial dynamics research, provide an exhaustive analysis of existing studies investigating the relationship between mitochondrial dynamics and acute injury, and shed light on their implications for AKI. The ultimate goal is to advance the development of more effective therapeutic interventions for managing AKI.

Equine Hoof Progenitor Cells Display Increased Mitochondrial Metabolism and Adaptive Potential to a Highly Pro-Inflammatory Microenvironment

Medicinal signaling cells (MSC) exhibit distinct molecular signatures and biological abilities, depending on the type of tissue they originate from. Recently, we isolated and described a new population of stem cells residing in the coronary corium, equine hoof progenitor cells (HPCs), which could be a new promising cell pool for the treatment of laminitis. Therefore, this study aimed to compare native populations of HPCs to well-established adipose-derived stem cells (ASCs) in standard culture conditions and in a pro-inflammatory milieu to mimic a laminitis condition. ASCs and HPCs were either cultured in standard conditions or subjected to priming with a cytokines cocktail mixture. The cells were harvested and analyzed for expression of key markers for phenotype, mitochondrial metabolism, oxidative stress, apoptosis, and immunomodulation using RT-qPCR. The morphology and migration were assessed based on fluorescent staining. Microcapillary cytometry analyses were performed to assess the distribution in the cell cycle, mitochondrial membrane potential, and oxidative stress. Native HPCs exhibited a similar morphology to ASCs, but a different phenotype. The HPCs possessed lower migration capacity and distinct distribution across cell cycle phases. Native HPCs were characterized by different mitochondrial dynamics and oxidative stress levels. Under standard culture conditions, HPCs displayed different expression patterns of apoptotic and immunomodulatory markers than ASCs, as well as distinct miRNA expression. Interestingly, after priming with the cytokines cocktail mixture, HPCs exhibited different mitochondrial dynamics than ASCs; however, the apoptosis and immunomodulatory marker expression was similar in both populations. Native ASCs and HPCs exhibited different baseline expressions of markers involved in mitochondrial dynamics, the oxidative stress response, apoptosis and inflammation. When exposed to a pro-inflammatory microenvironment, ASCs and HPCs differed in the expression of mitochondrial condition markers and chosen miRNAs.

LRRK2 Knockout Confers Resistance in HEK-293 Cells to Rotenone-Induced Oxidative Stress, Mitochondrial Damage, and Apoptosis

Leucine-rich repeat kinase 2 (LRRK2) has been linked to dopaminergic neuronal vulnerability to oxidative stress (OS), mitochondrial impairment, and increased cell death in idiopathic and familial Parkinson's disease (PD). However, how exactly this kinase participates in the OS-mitochondria-apoptosis connection is still unknown. We used clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 LRRK2 knockout (KO) in the human embryonic kidney cell line 293 (HEK-293) to evaluate the cellular response to the mitochondrial inhibitor complex I rotenone (ROT), a well-known OS and cell death inducer. We report successful knockout of the LRRK2 gene in HEK-293 cells using CRISPR editing (ICE, approximately 60%) and flow cytometry (81%) analyses. We found that HEK-293 LRRK2 WT cells exposed to rotenone (ROT, 50 μM) resulted in a significant increase in intracellular reactive oxygen species (ROS, +7400%); oxidized DJ-1-Cys¹⁰⁶-SO₃ (+52%); phosphorylation of LRRK2 (+70%) and c-JUN (+171%); enhanced expression of tumor protein (TP53, +2000%), p53 upregulated modulator of apoptosis (PUMA, +1950%), and Parkin (PRKN, +22%); activation of caspase 3 (CASP3, +8000%), DNA fragmentation (+35%) and decreased mitochondrial membrane potential (ΔΨm, -58%) and PTEN induced putative kinase 1 (PINK1, -49%) when compared to untreated cells. The translocation of the cytoplasmic fission protein dynamin-related Protein 1 (DRP1) to mitochondria was also observed by colocalization with translocase of the outer membrane 20 (TOM20). Outstandingly, HEK-293 LRRK2 KO cells treated with ROT showed unaltered OS and apoptosis markers. We conclude that loss of LRRK2 causes HEK-293 to be resistant to ROT-induced OS, mitochondrial damage, and apoptosis in vitro. Our data support the hypothesis that LRRK2 acts as a proapoptotic kinase by regulating mitochondrial proteins (e.g., PRKN, PINK1, DRP1, and PUMA), transcription factors (e.g., c-JUN and TP53), and CASP3 in cells under stress conditions. Taken together, these observations suggest that LRRK2 is an important kinase in the pathogenesis of PD.

Low-dose BPA and its substitute BPS promote ovarian cancer cell stemness via a non-canonical PINK1/p53 mitophagic signaling

The environmental toxicity of bisphenol A (BPA) and its analog like bisphenol S (BPS) have drawn wide attention, but their roles in cancer progression remain controversial. Here, we investigated the effect of BPA/BPS on the development of ovarian cancer. Human internal BPA/BPS exposure levels were analyzed from NHANES 2013-2016 data. We treated human ovarian cancer cells with 0-1000 nM BPA/BPS and found that 100 nM BPA/BPS treatment significantly increased Cancer Stem Cell (CSC) markers expression including OCT4, NANOG and SOX2. Cancer cell stemness evaluation induced by BPA/BPS was notably attenuated by the knockdown of PINK1 or Mdivi-1 treatment. The activation of PINK1 initiated mitophagy by inhibiting p-p53 nuclear translocation in a non-canonical manner. In vivo studies validated that BPA/BPS-exposed mice have higher tumor metastasis incidence compared with the control group, while mitophagy inhibition blocked such a promotion effect. In addition, CSC markers such as SOX2 had been found to be overexpressed in the tumor tissues of BPA/BPS exposure group. Taken together, the findings herein first provide the evidence that environmentally relevant BPA/BPS exposure could enhance ovarian cancer cell stemness through a non-canonical PINK1/p53 mitophagic pathway, raising concerns about the potential population hazards of BPA and other bisphenol analogs.

Photocatalytic oxygen evolution and antibacterial biomimetic repair membrane for diabetes wound repair via HIF1-α pathway

Diabetic wounds always have puzzled patients and caused serious social problems. Due to the lack of local blood vessels, severe hypoxia is generated in the defect area, which is an essential reason for the difficulty of wound healing. We have constructed a photocatalytic oxygen evolution and antibacterial biomimetic repair membrane to solve the problems of wound repair. A scanning electron microscope and transmission electron microscope characterized the biomimetic repair membrane. The oxygen evolution of the biomimetic membrane was tested by an oxygen meter. The excellent antibacterial performance of the biomimetic repair membrane was also verified by co-culture with Staphylococcus aureus and Escherichia coli. It was confirmed that the expression of collagen and HIF1-α in fibroblasts was significantly increased in vitro. And the mitochondrial activity of the vascular and nerve was increased considerably. In vivo, the healing time of diabetes wounds treated with the biomimetic repair membrane was significantly reduced, the collagen and the number of pores were increased considerably, and vascular regeneration was enhanced. The biomimetic repair membrane has an excellent performance in photocatalytic oxygen evolution and antibacterial and can significantly promote the repair of diabetes wounds. This will provide a promising treatment for diabetes wound repair.

Mitochondrial dysfunctions induce PANoptosis and ferroptosis in cerebral ischemia/reperfusion injury: from pathology to therapeutic potential

Ischemic stroke (IS) accounts for more than 80% of the total stroke, which represents the leading cause of mortality and disability worldwide. Cerebral ischemia/reperfusion injury (CI/RI) is a cascade of pathophysiological events following the restoration of blood flow and reoxygenation, which not only directly damages brain tissue, but also enhances a series of pathological signaling cascades, contributing to inflammation, further aggravate the damage of brain tissue. Paradoxically, there are still no effective methods to prevent CI/RI, since the detailed underlying mechanisms remain vague. Mitochondrial dysfunctions, which are characterized by mitochondrial oxidative stress, Ca²⁺ overload, iron dyshomeostasis, mitochondrial DNA (mtDNA) defects and mitochondrial quality control (MQC) disruption, are closely relevant to the pathological process of CI/RI. There is increasing evidence that mitochondrial dysfunctions play vital roles in the regulation of programmed cell deaths (PCDs) such as ferroptosis and PANoptosis, a newly proposed conception of cell deaths characterized by a unique form of innate immune inflammatory cell death that regulated by multifaceted PANoptosome complexes. In the present review, we highlight the mechanisms underlying mitochondrial dysfunctions and how this key event contributes to inflammatory response as well as cell death modes during CI/RI. Neuroprotective agents targeting mitochondrial dysfunctions may serve as a promising treatment strategy to alleviate serious secondary brain injuries. A comprehensive insight into mitochondrial dysfunctions-mediated PCDs can help provide more effective strategies to guide therapies of CI/RI in IS.

Pharmacological ascorbate potentiates combination nanomedicines and reduces cancer cell stemness to prevent post-surgery recurrence and systemic metastasis

Conventional chemotherapy targets proliferative cancer cells to halt tumor progression or regress tumors. However, the plasticity of tumor cells enables their phenotypical changes to acquire chemo-resistance, leading to treatment failure or tumor recurrence after a successful treatment course. Here, we report the use of high-dose pharmacologic ascorbate to potentiate treatment efficacy of nanoscale coordination polymers (NCPs) delivering two clinical combinations of chemotherapeutics, carboplatin/docetaxel and oxaliplatin/SN38, and to target metabolic plasticity of tumor cells. Combination treatments of high-dose ascorbate and NCPs overcome multi-drug resistance by significantly reducing the abundance of cancer stem cells (CSCs) in solid tumors, as evidenced by reduced expression of tumor pluripotency factors. The clearance of CSCs inhibits post-surgery recurrence and systemic metastasis in multiple mouse models of cancer.

The role of mitochondrial fission in intervertebral disc degeneration

Low back pain (LBP) is an extremely common disorder and is a major cause of disability globally. Intervertebral disc degeneration (IVDD) is the main contributor to LBP. Nevertheless, the specific mechanisms underlying the pathogenesis of IVDD remain unclear. Mitochondria are highly dynamic organelles that continuously undergo fusion and fission, known as mitochondrial dynamics. Accumulating evidence has revealed that aberrantly activated mitochondrial fission leads to mitochondrial fragmentation and dysfunction, which are involved in the development and progression of IVDD. To date, research into mitochondrial dynamics in IVDD is at an early stage. The present narrative review aims to summarize the most recent findings about the role of mitochondrial fission in the pathogenesis of IVDD.

Protective Effect of Electroacupuncture on the Barrier Function of Intestinal Injury in Endotoxemia through HO-1/PINK1 Pathway-Mediated Mitochondrial Dynamics Regulation

Background and Aims

Endotoxemia (ET) is a common critical illness in patients receiving intensive care and is associated with high mortality and prolonged hospital stay. The intestinal epithelial cell dysfunction is regarded as the "engine" of deteriorated ET. Although electroacupuncture (EA) can mitigate endotoxin-induced intestinal epithelial cell dysfunction in ET, the mechanism through which EA improves endotoxin-induced intestinal injury for preventing ET deterioration needs further investigation.

Methods

An in vivo ET model was developed by injecting lipopolysaccharide (LPS) in wild-type and PINK1-knockout mice. An in vitro model was also established by incubating epithelial cells in the serum samples obtained from both groups of mice. Hemin and zinc protoporphyrin IX (ZnPP) were applied to activate or inhibit heme oxygenase 1 (HO-1) production. EA treatment was performed for 30 min consecutively for 5 days before LPS injection, and on the day of the experiment, EA was performed throughout the process. Samples were harvested at 6 h after LPS induction for analyzing tissue injury, oxidative stress, ATP production, activity of diamine oxidase (DAO), and changes in the levels of HO-1, PTEN-induced putative kinase 1 (PINK1), mitochondrial fusion and fission marker gene, caspase-1, and interleukin 1 beta (IL-1β).

Results

In the wild-type models (both in vivo and vitro), EA alleviated LPS-induced intestinal injury and mitochondrial dysfunction, as indicated by decreased reactive oxygen species (ROS) production and oxygen consumption rate (OCR) and reduced levels of mitochondrial fission proteins. EA treatment also boosted histopathological morphology, ATP levels, DAO activity, and levels of mitochondrial fusion proteins in vivo and vitro. The effect of EA was enhanced by hemin but suppressed by Znpp. However, EA + AP, Znpp, or hemin had no effects on the LPS-induced, PINK1-knocked out mouse models.

Conclusion

EA may improve the HO-1/PINK1 pathway-mediated mitochondrial dynamic balance to protect the intestinal barrier in patients with ET.

Ginsenoside Rg1 ameliorates chronic intermittent hypoxia-induced vascular endothelial dysfunction by suppressing the formation of mitochondrial reactive oxygen species through the calpain-1 pathway

Background

As the major pathophysiological feature of obstructive sleep apnea (OSA), chronic intermittent hypoxia (CIH) is vital for the occurrence of cardiovascular complications. The activation of calpain-1 mediates the production of endothelial reactive oxygen species (ROS) and impairs nitric oxide (NO) bioavailability, resulting in vascular endothelial dysfunction (VED). Ginsenoside Rg1 is thought to against endothelial cell dysfunction, but the potential mechanism of CIH-induced VED remains unclear.

Methods

C57BL/6 mice and human coronary artery endothelial cells (HCAECs) were exposed to CIH following knockout or overexpression of calpain-1. The effect of ginsenoside Rg1 on VED, oxidative stress, mitochondrial dysfunction, and the expression levels of calpain-1, PP2A and p-eNOS were detected both in vivo and in vitro.

Results

CIH promoted VED, oxidative stress and mitochondrial dysfunction accompanied by enhanced levels of calpain-1 and PP2A and reduced levels of p-eNOS in mice and cellular levels. Ginsenoside Rg1, calpain-1 knockout, OKA, NAC and TEMPOL treatment protected against CIH-induced VED, oxidative stress and mitochondrial dysfunction, which is likely concomitant with the downregulated protein expression of calpain-1 and PP2A and the upregulation of p-eNOS in mice and cellular levels. Calpain-1 overexpression increased the expression of PP2A, reduced the level of p-eNOS, and accelerated the occurrence and development of VED, oxidative stress and mitochondrial dysfunction in HCAECs exposed to CIH. Moreover, scavengers of O₂ ^{• -}, H₂O₂, complex Ⅰ or mitoK_ATP abolished CIH-induced impairment in endothelial-dependent relaxation.

Conclusion

Ginsenoside Rg1 may alleviate CIH-induced vascular endothelial dysfunction by suppressing the formation of mitochondrial reactive oxygen species through the calpain-1 pathway.

Activation of the Nrf2/ARE signaling pathway protects against palmitic acid-induced renal tubular epithelial cell injury by ameliorating mitochondrial reactive oxygen species-mediated mitochondrial dysfunction

Chronic kidney disease (CKD) is often accompanied by dyslipidemia, and abnormal lipid metabolism in proximal tubule cells is considered closely related to the dysfunction of proximal tubule cells and eventually leads to accelerated kidney damage. Nuclear factor E2-related factor 2 (Nrf2), known as a redox-sensitive transcription factor, is responsible for regulating cellular redox homeostasis. However, the exact role of Nrf2 in dyslipidemia-induced dysfunction of proximal tubule cells is still not fully elucidated. In the present study, we showed that palmitic acid (PA) induced mitochondrial damage, excessive mitochondrial reactive oxygen species (ROS) (mtROS) generation, and cell injury in HK-2 cells. We further found that mtROS generation was involved in PA-induced mitochondrial dysfunction, cytoskeletal damage, and cell apoptosis in HK-2 cells. In addition, we demonstrated that the Nrf2/ARE signaling pathway was activated in PA-induced HK-2 cells and that silencing Nrf2 dramatically aggravated PA-induced mtROS production, mitochondrial damage, cytoskeletal damage and cell apoptosis in HK-2 cells. However, the mitochondrial antioxidant MitoTEMPOL effectively eliminated these negative effects of Nrf2 silencing in HK-2 cells under PA stimulation. Moreover, activation of the Nrf2/ARE signaling pathway with tBHQ attenuated renal injury, significantly reduced mtROS generation, and improved mitochondrial function in rats with HFD-induced obesity. Taken together, these results suggest that the Nrf2/ARE-mediated antioxidant response plays a protective role in hyperlipidemia-induced renal injury by ameliorating mtROS-mediated mitochondrial dysfunction and that enhancing Nrf2 antioxidant signaling provides a potential therapeutic strategy for kidney injury in CKD with hyperlipidemia.

Regulation of mitochondrial fusion and mitophagy by intra-tumoral delivery of membrane-fused mitochondria or Midiv-1 enhances sensitivity to doxorubicin in triple-negative breast cancer

Increasing mitochondrial fusion by intra-tumoral grafting of membrane-fused mitochondria created with Pep-1 conjugation (P-Mito) contributes to breast cancer treatment, but it needs to be validated. Using mitochondrial division inhibitor-1 (Mdivi-1, Mdi) to disturb mitochondrial dynamics, we showed that the antitumor action of P-Mito in a mouse model of triple-negative breast cancer depends upon mitochondrial fusion and that Mdi treatment alone is ineffective. P-Mito significantly enhanced Doxorubicin (Dox) sensitivity by inducing mitochondrial fusion and mitophagy, and the same efficiency was also achieved with Mdi by inhibiting mitophagy. Cell death was induced via the p53 pathway and AIF nuclear translocation in the case of P-Mito, versus the caspase-dependent pathway for Mdi. Notably, both mitochondrial treatments reduced oxidative stress and blood vessel density of xenograft tumors, especially P-Mito, which was accompanied by inhibition of nuclear factor kappa-B activation. Furthermore, through enrichment analysis, four microRNAs in serum microvesicles induced by P-Mito caused expression of predicted targets via the PI3K-Akt pathway, and significantly impacted regulation of nuclear processes and myeloid cell differentiation. Clustering of gene-sets implicated a major steroid catabolic network. This study showed diverse roles of mitochondria in breast cancer and revealed effective adjuvant therapy targeting mitochondrial fusion and mitophagy.

Fibroblast growth factor 21, a stress regulator, inhibits Drp1 activation to alleviate skeletal muscle ischemia/reperfusion injury

Abnormal Drp1 activation and subsequent excessive mitochondrial fission play a critical role in ischemia-reperfusion injury (I/RI). Although fibroblast growth factor 21 (FGF21) protects organs against I/RI and regulates metabolism, which indicates that FGF21 is involved in mitochondria homeostasis, the detailed mechanism remains unclear. Herein, we investigated whether FGF21 had an effect on Drp1 activation during skeletal muscle I/RI. Drp1 phosphorylation and its translocation to mitochondria, as regulated by FGF21, was examined in mouse and C2C12 cell I/RI models. Mice overexpressing FGF21 displayed alleviation of serum index, histological lesions and apoptosis levels. Moreover, FGF21 markedly decreased cyclin-dependent kinase 1 (CDK1) and Drp1 phosphorylation at Ser616, accompanied by reduced accumulation in mitochondria. In parallel in vitro studies, cells with FGF21 knockdown displayed enhanced Drp1 activation, and the reverse effect was found when FGF21 was added. More importantly, FGF21 attenuated mitochondrial fission with linear mitochondria rather than fragmented mitochondria. Furthermore, a CDK1 inhibitor reduced Drp1 activation and mitochondrial fission due to FGF21 knockdown. This study shows that FGF21 inhibits Drp1 activation to protect mitochondria from fission, thereby rescuing cells from I/RI-induced apoptosis. Our findings may provide a new therapeutic approach to ameliorate skeletal muscle I/RI.

Modulating mitofusins to control mitochondrial function and signaling

Mitofusins reside on the outer mitochondrial membrane and regulate mitochondrial fusion, a physiological process that impacts diverse cellular processes. Mitofusins are activated by conformational changes and subsequently oligomerize to enable mitochondrial fusion. Here, we identify small molecules that directly increase or inhibit mitofusins activity by modulating mitofusin conformations and oligomerization. We use these small molecules to better understand the role of mitofusins activity in mitochondrial fusion, function, and signaling. We find that mitofusin activation increases, whereas mitofusin inhibition decreases mitochondrial fusion and functionality. Remarkably, mitofusin inhibition also induces minority mitochondrial outer membrane permeabilization followed by sub-lethal caspase-3/7 activation, which in turn induces DNA damage and upregulates DNA damage response genes. In this context, apoptotic death induced by a second mitochondria-derived activator of caspases (SMAC) mimetic is potentiated by mitofusin inhibition. These data provide mechanistic insights into the function and regulation of mitofusins as well as small molecules to pharmacologically target mitofusins.

Mitochondrial fission induces immunoescape in solid tumors through decreasing MHC-I surface expression

Mitochondrial dynamics can regulate Major Histocompatibility Complex (MHC)-I antigen expression by cancer cells and their immunogenicity in mice and in patients with malignancies. A crucial role in the mitochondrial fragmentation connection with immunogenicity is played by the IRE1α-XBP-1s axis. XBP-1s is a transcription factor for aminopeptidase TPP2, which inhibits MHC-I complex cell surface expression likely by degrading tumor antigen peptides. Mitochondrial fission inhibition with Mdivi-1 upregulates MHC-I expression on cancer cells and enhances the efficacy of adoptive T cell therapy in patient-derived tumor models. Therefore mitochondrial fission inhibition might provide an approach to enhance the efficacy of T cell-based immunotherapy.

Mitochondrial Dysfunction in Cardiovascular Diseases: Potential Targets for Treatment

Cardiovascular diseases (CVDs) are serious public health issues and are responsible for nearly one-third of global deaths. Mitochondrial dysfunction is accountable for the development of most CVDs. Mitochondria produce adenosine triphosphate through oxidative phosphorylation and inevitably generate reactive oxygen species (ROS). Excessive ROS causes mitochondrial dysfunction and cell death. Mitochondria can protect against these damages via the regulation of mitochondrial homeostasis. In recent years, mitochondria-targeted therapy for CVDs has attracted increasing attention. Various studies have confirmed that clinical drugs (β-blockers, angiotensin-converting enzyme inhibitors/angiotensin receptor-II blockers) against CVDs have mitochondrial protective functions. An increasing number of cardiac mitochondrial targets have shown their cardioprotective effects in experimental and clinical studies. Here, we briefly introduce the mechanisms of mitochondrial dysfunction and summarize the progression of mitochondrial targets against CVDs, which may provide ideas for experimental studies and clinical trials.

Piperlongumine, a piper alkaloid, enhances the efficacy of doxorubicin in breast cancer: involvement of glucose import, ROS, NF-κB and lncRNAs

Piperlongumine (PL, piplartine) is an alkaloid derived from the Piper longum L. (long pepper) roots. Originally discovered in 1961, the biological activities of this molecule against some cancer types was reported during the last decade. Whether PL can synergize with doxorubicin and the underlying mechanism in breast cancer remains elusive. Herein, we report the activities of PL in numerous breast cancer cell lines. PL reduced the migration and colony formation by cancer cells. An enhancement in the sub-G1 population, reduction in the mitochondrial membrane potential, chromatin condensation, DNA laddering and suppression in the cell survival proteins was observed by the alkaloid. Further, PL induced ROS generation in breast cancer cells. While TNF-α induced p65 nuclear translocation, PL suppressed the translocation in cancer cells. The expression of lncRNAs such as MEG3, GAS5 and H19 were also modulated by the alkaloid. The molecular docking studies revealed that PL can interact with both p65 and p50 subunits. PL reduced the glucose import and altered the pH of the medium towards the alkaline side. PL also suppressed the expression of glucose and lactate transporter in breast cancer cells. In tumor bearing mouse model, PL was found to synergize with doxorubicin and reduced the size, volume and weight of the tumor. Overall, the effects of doxorubicin in cancer cells are enhanced by PL. The modulation of glucose import, NF-κB activation and lncRNAs expression may have contributory role for the activities of PL in breast cancer.

Drp1-Mediated Mitochondrial Metabolic Dysfunction Inhibits the Tumor Growth of Pituitary Adenomas

Metabolic changes have been suggested to be a hallmark of tumors and are closely associated with tumorigenesis. In a previous study, we demonstrated the role of lactate dehydrogenase in regulating abnormal glucose metabolism in pituitary adenomas (PA). As the key organelle of oxidative phosphorylation (OXPHOS), mitochondria play a vital role in the energy supply for tumor cells. However, few attempts have been made to elucidate mitochondrial metabolic homeostasis in PA. Dynamin-related protein 1 (Drp1) is a member of the dynamin superfamily of GTPases, which mediates mitochondrial fission. This study is aimed at investigating whether Drp1 affects the progression of PA through abnormal mitochondrial metabolism. We analyzed the expression of dynamin-related protein 1 (Drp1) in 20 surgical PA samples. The effects of Drp1 on PA growth were assessed in vitro and in xenograft models. We found an upregulation of Drp1 in PA samples with a low proliferation index. Knockdown or inhibition of Drp1 enhanced the proliferation of PA cell lines in vitro, while overexpression of Drp1 could reversed such effects. Mechanistically, overexpressed Drp1 damaged mitochondria by overproduction of reactive oxygen species (ROS), which induced mitochondrial OXPHOS inhibition and decline of ATP production. The energy deficiency inhibited proliferation of PA cells. In addition, overexpressed Drp1 promoted cytochrome c release from damaged mitochondria into the cytoplasm and then activated the downstream caspase apoptotic cascade reaction, which induced apoptosis of PA cells. Moreover, the decreased ATP production induced by Drp1 overexpressing activated the AMPK cellular energy stress sensor and enhanced autophagy through the AMPK-ULK1 pathway, which might play a protective role in PA growth. Furthermore, overexpression of Drp1 repressed PA growth in vivo. Our data indicates that Drp1-mediated mitochondrial metabolic dysfunction inhibits PA growth by affecting cell proliferation, apoptosis, and autophagy. Selectively targeting mitochondrial metabolic homeostasis stands out as a promising antineoplastic strategy for PA therapy.

PIWI-Interacting RNA HAAPIR Regulates Cardiomyocyte Death After Myocardial Infarction by Promoting NAT10-Mediated ac4 C Acetylation of Tfec mRNA

PIWI-interacting RNAs (piRNAs) are abundantly expressed in heart. However, their functions and molecular mechanisms during myocardial infarction remain unknown. Here, a heart-apoptosis-associated piRNA (HAAPIR), which regulates cardiomyocyte apoptosis by targeting N-acetyltransferase 10 (NAT10)-mediated N4-acetylcytidine (ac⁴ C) acetylation of transcription factor EC (Tfec) mRNA transcript, is identified. HAAPIR deletion attenuates ischemia/reperfusion induced myocardial infarction and ameliorate cardiac function compared to WT mice. Mechanistically, HAAPIR directly interacts with NAT10 and enhances ac⁴ C acetylation of Tfec mRNA transcript, which increases Tfec expression. TFEC can further upregulate the transcription of BCL2-interacting killer (Bik), a pro-apoptotic factor, which results in the accumulation of Bik and progression of cardiomyocyte apoptosis. The findings reveal that piRNA-mediated ac⁴ C acetylation mechanism is involved in the regulation of cardiomyocyte apoptosis. HAAPIR-NAT10-TFEC-BIK signaling axis can be potential target for the reduction of myocardial injury caused by cardiomyocyte apoptosis in ischemia heart diseases.

SIRT2 regulates mitochondrial dynamics and reprogramming via MEK1-ERK-DRP1 and AKT1-DRP1 axes

During somatic reprogramming, cellular energy metabolism fundamentally switches from predominantly mitochondrial oxidative phosphorylation toward glycolysis. This metabolic reprogramming, also called the Warburg effect, is critical for the induction of pluripotency, but its molecular mechanisms remain poorly defined. Notably, SIRT2 is consistently downregulated during the reprogramming process and regulates glycolytic switch. Here, we report that downregulation of SIRT2 increases acetylation of mitogen-activated protein kinase (MAPK) kinase-1 (MEK1) at Lys175, resulting in activation of extracellular signal-regulated kinases (ERKs) and subsequent activation of the pro-fission factor dynamin-related protein 1 (DRP1). In parallel, downregulation of SIRT2 hyperacetylates the serine/threonine protein kinase AKT1 at Lys20 in a non-canonical way, activating DRP1 and metabolic reprogramming. Together, our study identified two axes, SIRT2-MEK1-ERK-DRP1 and SIRT2-AKT1-DRP1, that critically link mitochondrial dynamics and oxidative phosphorylation to the somatic reprogramming process. These upstream signals, together with SIRT2’s role in glycolytic switching, may underlie the Warburg effect observed in human somatic cell reprogramming.

Mitochondrial remodeling has critical roles for the somatic cell reprogramming process. Cha et al. report the functional role of SIRT2 in mitochondrial dynamics and remodeling during the human somatic cell reprogramming process. They identify two axes, SIRT2-MEK1-ERK-DRP1 and SIRT2-AKT1-DRP1, that link SIRT2 downregulation to mitochondrial remodeling and somatic cell reprogramming.

Mitochondria and Their Relationship with Common Genetic Abnormalities in Hematologic Malignancies

Hematologic malignancies are known to be associated with numerous cytogenetic and molecular genetic changes. In addition to morphology, immunophenotype, cytochemistry and clinical characteristics, these genetic alterations are typically required to diagnose myeloid, lymphoid, and plasma cell neoplasms. According to the current World Health Organization (WHO) Classification of Tumors of Hematopoietic and Lymphoid Tissues, numerous genetic changes are highlighted, often defining a distinct subtype of a disease, or providing prognostic information. This review highlights how these molecular changes can alter mitochondrial bioenergetics, cell death pathways, mitochondrial dynamics and potentially be related to mitochondrial genetic changes. A better understanding of these processes emphasizes potential novel therapies.

Targeting protein interaction networks in mitochondrial dynamics for cancer therapy

Mitochondria are crucial organelles that provide energy via oxidative phosphorylation in eukaryotic cells and also have critical roles in growth, division, and the cell cycle, as well as the rapid adaptation required to meet the metabolic needs of the cell. Mitochondrial processes are highly dynamic; fusion and fission can vary with cell type, cellular context, and stress levels. Accumulating evidence demonstrates that an imbalance in mitochondrial dynamics leads to death in numerous types of human cancer cells. Therefore, modulating mitochondrial dynamics could be a therapeutic target. In this review, we provide an overview of the protein interaction networks involved in mitochondrial dynamics as effective and feasible drug targets and discuss the related potential therapeutic strategies for cancer.

Iron-bearing nanoparticles trigger human umbilical vein endothelial cells ferroptotic responses by promoting intracellular iron level

Iron-bearing nanoparticles (IBNPs) were abundant in particulate matter (PM). Due to their high reactivity, IBNPs were considered hazardous to human health, however, their toxic mode-of-action(s) are highly unclear. Ferroptosis is a novel programmed cell death (PCD) that highly associated with intracellular iron. However, the pro-ferroptotic effect of IBNPs has not been characterized. To this end, we ought to investigate whether and how IBNPs (synthetic γ-Fe₂O₃ and Fe₃O₄ NPs were selected as the model compounds) are involved in ferroptosis. We found that human umbilical vein endothelial cells (HUVECs) phagocytized large qualities of γ-Fe₂O₃ and Fe₃O₄ NPs, resulting in increased intracellular iron level. We further observed the disrupted cystine/glutamate reverse transporter (System X_c^-) and glutathione peroxidase 4 (GPX4) signaling in γ-Fe₂O₃ and Fe₃O₄ NPs-challenged HUVECs. γ-Fe₂O₃ and Fe₃O₄ NPs could also cause mitochondrial fusion and fission dysregulation, activate lipid peroxidation and iron metabolism-related genes in a P53-dependent manner. Together, the ferroptotic activity of IBNPs should be acknowledged for the risk assessment of PM associated health effects.

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

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

Melatonin Protects Against Mdivi-1-Induced Abnormal Spindle Assembly and Mitochondrial Superoxide Production During Porcine Oocyte Maturation

Mitochondrial division inhibitor 1 (Mdivi-1) reportedly provides a close connection between oocyte maturation and mitochondrial function in pigs. N-acetyl-5-methoxy-tryptamine (melatonin) is known to be a representative antioxidant with the ability to rehabilitate meiotic maturation of porcine oocytes. However, the ability of melatonin to recover Mdivi-1-mediated disruption of spindle formation during meiotic maturation of porcine oocytes during in vitro maturation (IVM) has not been studied. Here, we first investigated changes in mitochondrial length, such as fragmentation and elongation form, in mature porcine oocytes during IVM. Mature oocytes require appropriate mitochondrial fission for porcine oocyte maturation. We identified a dose-dependent reduction in meiotic maturation in porcine oocytes following Mdivi-1 treatment (50, 75, and 100 μM). We also confirmed changes in mitochondrial fission protein levels [dynamin-related protein 1 phosphorylation at serine 616 (pDRP1-Ser616) and dynamin-related protein 1 (DRP1)], mitochondrial membrane potential, and ATP production in 75 μM Mdivi-1-treated oocytes. As expected, Mdivi-1 significantly reduced mitochondrial function and DRP1 protein levels and increased spindle abnormalities in porcine oocytes. In addition, we confirmed that melatonin restores abnormal spindle assembly and reduces meiotic maturation rates by Mdivi-1 during porcine oocyte maturation. Interestingly, the expression levels of genes that reduce DNA damage and improve tubulin formation were enhanced during porcine meiotic maturation. Taken together, these results suggest that melatonin has direct beneficial effects on meiotic maturation through tubulin formation factors during porcine oocyte maturation.

Effects of sodium arsenite and dimethyl arsenic acid on Liaoning cashmere goat skin fibroblasts

The morphology and oxidation state of arsenic in its compounds affects the skin cell toxicity. Accordingly, the present study was conducted to explore the effects of two different arsenic compounds on the proliferation and survival of Liaoning cashmere goat skin fibroblasts. Based on MTT assay results, at 24 h, the proliferation concentration, critical concentration, and half inhibitory concentration (IC50) of sodium arsenite were 0.50, 5.00, and 45.66 μmol/L, respectively. The corresponding values for dimethyl arsenic acid were 0.85, 1.00, and 38.68 mmol/L. Immunofluorescence, transmission electron microscopy, and mitochondria membrane potential (MMP) assays showed that sodium arsenite promotes microtubule polymerization and increases MMP, while cells treated with dimethyl arsenic acid exhibited cytoskeletal collapse and decreased MMP. In the IC50 groups for both arsenic agents, the cytoskeletons collapsed, microtubules were gathered into bundles, and MMP was significantly decreased. Dimethyl arsenic acid had a stronger effect on MMP than sodium arsenite. Flow cytometry revealed a slightly lower occurrence of apoptosis in the sodium arsenite proliferation group, while it was slightly increased in the dimethyl arsenic acid proliferation group. Apoptosis was increased more significantly in the sodium arsenite IC50 group than in the dimethyl arsenic acid IC50 group. These results indicate that the differences in cell proliferation and cytotoxicity induced by inorganic and organic arsenic are related to their effects on cellular structures.

LKB1/AMPKα signaling pathway and mitochondrial fission/fusion dynamics regulate apoptosis induced by 3-chlorpropane-1,2-diol in HEK293 cells

Mitochondrial dynamics and bioenergetics are considered play pivotal roles in the maintenance of mitochondrial function and cell viability. During the widely distributed food contaminant 3-chlorpropane-1,2-diol (3-MCPD) induced nephrotoxicity, mitochondrial morphology and function were impaired, but the specific mechanism responsible for the process has not been fully elucidated. In the present study, using an in vitro human embryonic kidney 293 (HEK293) cell culture model, the role of LKB1/AMPK pathway and mitochondrial fission and fusion dynamics in 3-MCPD-induced cell apoptosis was investigated by using the AMPK inhibitor dorsomorphin and mitochondrial division inhibitor 1 (Mdivi-1), respectively. The results revealed that 3-MCPD significantly decreased the ATP levels, activated the energy-sensing regulator AMPKα and its upstream protein kinase LKB1, disrupted mitochondrial dynamics equilibrium characterized by promoting division and inhibiting fusion, thus inducing cell apoptosis. Notably, suppression of AMPK by dorsomorphin mitigated 3-MCPD-induced cytotoxicity through improvement of the function and dynamics of mitochondria and alleviated apoptosis via the mitochondria-dependent pathway. Moreover, inhibition of mitochondrial fission by Mdivi-1 protected against apoptosis induced by 3-MCPD. Taken together, these results suggest that 3-MCPD triggers apoptosis through activation of LKB1/AMPKα signaling pathway and regulation of mitochondrial fission and fusion dynamics in HEK293 cells.

DDAH2 suppresses RLR-MAVS-mediated innate antiviral immunity by stimulating nitric oxide-activated, Drp1-induced mitochondrial fission

The RIG-I-like receptor (RLR) signaling pathway is pivotal for innate immunity against invading viruses, and dysregulation of this molecular cascade has been linked to various diseases. Here, we identified dimethylarginine dimethylaminohydrolase 2 (DDAH2) as a potent regulator of the RLR-mediated antiviral response in human and mouse. Overexpression of DDAH2 attenuated RLR signaling, whereas loss of DDAH2 function enhanced RLR signaling and suppressed viral replication ex vivo and in mice. Upon viral infection, DDAH2 relocated to mitochondria, where it induced the production of nitric oxide (NO) and the activation of dynamin-related protein 1 (Drp1), which promoted mitochondrial fission and blocked the activation of innate immune responses mediated by mitochondrial antiviral signaling (MAVS). TANK-binding kinase 1 (TBK1), a kinase downstream of MAVS, inhibited DDAH2 by phosphorylating DDAH2 at multiple sites. Our study thus identifies a reciprocal inhibitory loop between the DDAH2-NO cascade and the RLR signaling pathway that fine-tunes the antiviral immune response.

Pharmacological inhibition of mitochondrial fission attenuates oxidative stress-induced damage of retinal pigmented epithelial cells

Mitochondria maintain their function by the process of mitochondrial dynamics, which involves repeated fusion and fission. It is thought that the failure of mitochondrial dynamics, especially excessive fission, is related to the progression of several diseases. A previous study demonstrated that mitochondrial fragmentation occurs in the retinal pigmented epithelial (RPE) cells of patients with non-exudative age-related macular degeneration (AMD). We predicted that the suppression of mitochondrial fragmentation offers a novel therapeutic strategy for non-exudative AMD. We investigated whether the inhibition of mitochondrial fission was effective against the oxidative stress-induced damage of ARPE-19 cells. The treatment of ARPE-19 cells with H₂O₂ caused mitochondrial fragmentation, but treatment with mitochondrial division inhibitor 1 (Mdivi-1) suppressed fragmentation. Additionally, Mdivi-1 protected ARPE-19 cells against H₂O₂-induced damage, and suppressed the release of cytochrome c from the mitochondria. Mitochondrial function was evaluated by staining with JC-1 and measuring the production of reactive oxygen species (ROS), which revealed that mitochondrial function improved in the Mdivi-1-treated group. These findings indicated that the inhibition of mitochondrial fission would be a novel therapeutic target for non-exudative AMD.

Diabetes impairs the protective effects of sevoflurane postconditioning in the myocardium subjected to ischemia/ reperfusion injury in rats: important role of Drp1

BACKGROUND

Sevoflurane postconditioning (SevP) effectively relieves myocardial ischemia/reperfusion (I/R) injury but performs poorly in the diabetic myocardium. Previous studies have revealed the important role of increased oxidative stress in diabetic tissues. Notably, mitochondrial fission mediated by dynamin-related protein 1 (Drp1) is an upstream pathway of reactive oxygen production. Whether the ineffectiveness of SevP in the diabetic myocardium is related to Drp1-dependent mitochondrial fission remains unknown. This study aimed to explore the important role of Drp1 in the diabetic myocardium and investigate whether Drp1 inhibition could restore the cardioprotective effect of SevP.

METHODS

In the first part of the study, adult male Sprague-Dawley rats were divided into 6 groups. Rats in the diabetic groups were fed with high-fat and high-sugar diets for 8 weeks and injected intraperitoneally with streptozotocin (35 mg/kg). Myocardial I/R was induced by 30 min of occlusion of the left anterior descending branch of the coronary artery followed by 120 min of reperfusion. SevP was applied by continuous inhalation of 2.5 % sevoflurane 1 min before reperfusion, which lasted for 10 min. In the second part of the study, we applied mdivi-1 to investigate whether Drp1 inhibition could restore the cardioprotective effect of SevP in the diabetic myocardium. The myocardial infarct size, mitochondrial ultrastructure, apoptosis index, SOD activity, MDA content, and Drp1 expression were detected.

RESULTS

TTC staining and TUNEL results showed that the myocardial infarct size and apoptosis index were increased in the diabetic myocardium. However, SevP significantly alleviated myocardial I/R injury in the normal myocardium but not in the diabetic myocardium. Additionally, we found an elevation in Drp1 expression, accompanied by more severe fission-induced structural damage and oxidative stress in the diabetic myocardium. Interestingly, we discovered that the beneficial effect of SevP was restored by mdivi-1, which significantly suppressed mitochondrial fission and oxidative stress.

CONCLUSIONS

Our study demonstrates the crucial role of mitochondrial fission dependent on Drp1 in the diabetic myocardium subjected to I/R, and strongly indicates that Drp1 inhibition may restore the cardioprotective effect of SevP in diabetic rats.

A sphingosine kinase 2-mimicking TAT-peptide protects neurons against ischemia-reperfusion injury by activating BNIP3-mediated mitophagy

We have previously shown that sphingosine kinase 2 (SPK2) interacts with Bcl-2 via its BH3 domain, activating autophagy by inducing the dissociation of Beclin-1/Bcl-2 complexes, and that a TAT-SPK2 peptide containing the BH3 domain of SPK2 protects neurons against ischemic injury. The goals of the present study were to establish the functional significance of these findings, by testing whether TAT-SPK2 was effective in a mouse model of ischemic stroke, and to explore potential underlying mechanisms. Mice were administered with TAT-SPK2 by intraperitoneal injection before or after transient middle cerebral artery occlusion (tMCAO). Infarct volume, neurological deficit and brain water content were assessed 24 h after reperfusion. Mitophagy inhibitor Mdivi-1 and BNIP3 siRNAs were used to examine the involvement of BNIP3-dependent mitophagy in the neuroprotection of TAT-SPK2. Mitophagy was quantified by immunoblotting, immunofluorescence and electron microscopy. The interaction between TAT-SPK2 and Bcl-2, Bcl-2 and BNIP3 was detected by co-immunoprecipitation. In the tMCAO model, pre-treatment with TAT-SPK2 significantly reduced infarct volume, improved neurological function and decreased brain edema. Neuroprotection by TAT-SPK2 was still seen when the peptide was administered 3 h after reperfusion. TAT-SPK2 also significantly improved functional recovery and reduced long-term brain atrophy of the ischemic hemisphere 30 days after administration. Our studies further showed that TAT-SPK2 directly binds to Bcl-2 and disrupts Bcl-2/Beclin-1 or Bcl-2/BNIP3 complexes to induce mitophagy. These results suggest that TAT-SPK2 protects neurons against ischemia reperfusion injury by activating BNIP3-mediated mitophagy. Agents exploiting this molecular mechanism are potential candidates for the treatment of ischemic stroke.

Mitochondrial dysfunction in the development and progression of neurodegenerative diseases

In addition to ATP synthesis, mitochondria are highly dynamic organelles that modulate apoptosis, ferroptosis, and inflammasome activation. Through executing these varied functions, the mitochondria play critical roles in the development and progression of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, and Friedreich ataxia, among others. Impaired mitochondrial biogenesis and abnormal mitochondrial dynamics contribute to mitochondrial dysfunction in these diseases. Additionally, dysfunctional mitochondria play critical roles in signaling for both inflammasome activation and ferroptosis. Therapeutics are being developed to circumvent inflammasome activation and ferroptosis in dysfunctional mitochondria. Targeting these aspects of mitochondrial dysfunction may present viable therapeutic strategies for combatting the neurodegenerative diseases. This review aims to summarize the role of the mitochondria in the development and progression of neurodegenerative diseases and to present current therapeutic approaches that target mitochondrial dysfunction in these diseases.

Tongmai formula improves cardiac function via regulating mitochondrial quality control in the myocardium with ischemia/reperfusion injury

BACKGROUND

Mitochondrial quality control, regulated by mitochondrial dynamics and mitophagy, has been regarded as pivotal process to induce segregation of mitochondria during myocardial ischemia/reperfusion (I/R) injury. However, few works revealed the regulation of mitochondrial quality control by therapeutic agents. Tongmai formula (TM) is a clinically used botanical drug for treating cardiovascular diseases, which mechanism is unveiled. Thus, in this study, we investigated the pharmacological effects of TM on modulating mitochondrial quality control during cardiac injury.

METHODS

Rats subjected to myocardial I/R injury and neonatal rat ventricular myocytes (NRVMs) exposed to hypoxia/reoxygenation (H/R) were used to simulate cardiac injury during myocardial ischemia/reperfusion process. Morphological examination, histopathological examination, echocardiography, and immunohistochemistry were used to determine the cardiac injury after I/R injury. Biochemical indices in serum were estimated by the enzyme-linked immunosorbent assays (ELISA). 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide (JC-1) was used for mitochondrial membrane potential (ΔΨm) evaluation. 2',7'-dichlorofluorescin diacetate (DCFH-DA) was used for intracellular reactive oxygen species (ROS) evaluation. Mitochondria in NRVMs were labeled by tetramethylrhodamine methyl ester (TMRM) for mitochondrial morphosis imaging and estimation. Western blotting was used for cytochrome c (CYCS), apoptosis inducing factor (AIF) and mitofusin 2 (Mfn2) contents evaluation. Immunochemistry fluorescence was used for dynamin related protein 1 (Drp1) expression measurement.

RESULTS

TM treatment markedly decreased myocardium infarct size. It also significantly improved left ventricular contractile function and alleviated cardiomyocytes apoptosis, as well as reduced the production of cardiac troponin T, creatine kinase, lactate dehydrogenase, malondialdehyde and elevated glutathione and superoxide dismutase. Intriguingly, we found that mitochondrial membrane potential loss and mitochondrial permeability transition pore (mPTP) opening were recovered after TM treatment. It also down-regulated cytochrome c and apoptosis inducing factor contents after myocardial I/R injury. In vitro study showed that TM treatment reduced intracellular ROS content and recovered ΔΨ_m in NRVMs after H/R injury. We also observed that TM could reduce the expression level of Drp1, while increased Mfn2 in NRVMs after H/R injury, which indicates that TM may regulate mitochondrial dynamics during H/R injury of NRVMs.

CONCLUSIONS

TM exhibited cardiac protective effect on ischemic myocardium of rats after reperfusion and improved mitochondrial quality control through mitochondrial dynamics in NRVMs after H/R injury.

Cannabinoid CB1 receptor agonist ACEA alleviates brain ischemia/reperfusion injury via CB1-Drp1 pathway

Activation of the cannabinoid CB1 receptor induces neuroprotection against brain ischemia/reperfusion injury (IRI); however, the mechanism is still unknown. In this study, we used oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in neuronal cells and middle cerebral artery occlusion (MCAO)-induced brain IRI in rats to mimic ischemic brain injury, and hypothesized that the CB1 receptor agonist arachidonyl-2-chloroethylamide (ACEA) would protect ischemic neurons by inhibiting mitochondrial fission via dynamin-related protein 1 (Drp1). We found that OGD/R injury reduced cell viability and mitochondrial function, increased lactate dehydrogenase (LDH) release, and increased cell apoptosis, and mitochondrial fission. Notably, ACEA significantly abolished the OGD/R-induced neuronal injuries described above. Similarly, ACEA significantly reversed MCAO-induced increases in brain infarct volume, neuronal apoptosis and mitochondrial fission, leading to the recovery of neurological functions. The neuroprotective effects of ACEA were obviously blocked by coadministration of the CB1 receptor antagonist AM251 or by the upregulation of Drp1 expression, indicating that ACEA alleviates brain IRI via the CB1-Drp1 pathway. Our findings suggest that the CB1 receptor links aberrant mitochondrial fission to brain IRI, providing a new therapeutic target for brain IRI treatment.

Potential signaling pathway through which Notch regulates oxidative damage and apoptosis in renal tubular epithelial cells induced by high glucose

Diabetic nephropathy (DN) is one of the most common and serious complications of diabetes mellitus, and glomerular sclerosis and renal tubular interstitial fibrosis are the main pathological features. Current evidence indicates that the Notch pathway can mediate the impairment of renal tubular function and induce angiogenesis and renal interstitial fibrosis. This study was conducted to explore the potential signaling pathway through which Notch regulates oxidative damage and apoptosis in renal tubular epithelial cells induced by high glucose. mRNA and protein expression levels were assessed using real-time PCR and Western blot, respectively. The protein expression levels of Jaggedl, Notchl, pro-caspase-3, Drpl, and PGC-1α were increased by high glucose, but N-[N-(3,5-difluorohenacetyl)-l-alanyl]-S-phenylglycine tert-butyl ester (DAPT; an inhibitor of the Notch signaling pathway) reversed these effects. Furthermore, DAPT reduced the mRNA expression of Jaggedl, Notchl, MnSOD2, Drpl, and PGC-1α in renal tubular epithelial cells induced by high glucose. In conclusion, the Notch signaling pathway may regulate oxidative damage and apoptosis in renal tubular epithelial cells induced by high glucose by regulating mitochondrial dynein and biogenesis genes, which can accelerate renal interstitial fibrosis in DN. The Notch signaling pathway might be a potential therapeutic target for DN, and DAPT might become a potential drug for the treatment of DN.

Mitochondrial destiny in type 2 diabetes: the effects of oxidative stress on the dynamics and biogenesis of mitochondria

Background

One reason for the development of insulin resistance is the chronic inflammation in obesity.

Materials & Methods

Scientific articles in the field of knowledge on the involvement of mitochondria and mitochondrial DNA (mtDNA) in obesity and type 2 diabetes were analyzed.

Results

Oxidative stress developed during obesity contributes to the formation of peroxynitrite, which causes cytochrome C-related damage in the mitochondrial electron transfer chain and increases the production of reactive oxygen species (ROS), which is associated with the development of type 2 diabetes. Oxidative stress contributes to the nuclease activity of the mitochondrial matrix, which leads to the accumulation of cleaved fragments and an increase in heteroplasmy. Mitochondrial dysfunction and mtDNA variations during insulin resistance may be connected with a change in ATP levels, generation of ROS, mitochondrial division/fusion and mitophagy. This review discusses the main role of mitochondria in the development of insulin resistance, which leads to pathological processes in insulin-dependent tissues, and considers potential therapeutic directions based on the modulation of mitochondrial biogenesis. In this regard, the development of drugs aimed at the regulation of these processes is gaining attention.

Conclusion

Changes in the mtDNA copy number can help to protect mitochondria from severe damage during conditions of increased oxidative stress. Mitochondrial proteome studies are conducted to search for potential therapeutic targets. The use of mitochondrial peptides encoded by mtDNA also represents a promising new approach to therapy.

Transcription factor MoMsn2 targets the putative 3-methylglutaconyl-CoA hydratase-encoding gene MoAUH1 to govern infectious growth via mitochondrial fusion/fission balance in Magnaporthe oryzae

Mitochondrial quality and quantity are essential for a cell to maintain normal cellular functions. Our previous study revealed that the transcription factor MoMsn2 plays important roles in the development and virulence of Magnaporthe oryzae. However, to date, no study has reported its underlying regulatory mechanism in phytopathogens. Here, we explored the downstream target genes of MoMsn2 using a chromatin immunoprecipitation sequencing (ChIP-Seq) approach. In total, 332 target genes and five putative MoMsn2-binding sites were identified. The 332 genes exhibited a diverse array of functions and the highly represented were genes involved in metabolic and catalytic processes. Based on the ChIP-Seq data, we found that MoMsn2 plays a role in maintaining mitochondrial morphology, likely by targeting a number of mitochondria-related genes. Further investigation revealed that MoMsn2 targets the putative 3-methylglutaconyl-CoA hydratase-encoding gene (MoAUH1) to control mitochondrial morphology and mitophagy, which are critical for the infectious growth of the pathogen. Meanwhile, the deletion of MoAUH1 resulted in phenotypes similar to the ΔMomsn2 mutant in mitochondrial morphology, mitophagy and virulence. Overall, our results provide evidence for the regulatory mechanisms of MoMsn2, which targets MoAUH1 to modulate its transcript levels, thereby disturbing the mitochondrial fusion/fission balance. This ultimately affects the development and virulence of M. oryzae.