Inhibition of Drp1-dependent mitochondrial fission by natural compounds as a therapeutic strategy for organ injuries

Neurotoxicity of Realgar: Crosstalk Between UBXD8-DRP1-Regulated Mitochondrial Fission and PINK1-Parkin-Mediated Mitophagy

Realgar is a toxic mineral medicine containing arsenic that is present in many traditional Chinese medicines. It has been reported that the abuse of drugs containing realgar has potential neurotoxicity, but its mechanism of toxicity has not been fully clarified. In this study, we demonstrated that arsenic in realgar promoted mitochondrial fission via UBXD8-mediated DRP1 translocation to the mitochondria and activated mitophagy via PINK1-Parkin, resulting in mitochondrial dysfunction and nerve cell death in the rat cortex. We used PC12 cells and treated them with inorganic arsenic (iAs). Mdivi-1, a mitochondrial fission inhibitor, and the siRNA UBXD8 or PINK1 were used as interventions to verify the precise mechanism by which arsenic affects realgar-induced mitochondrial instability. The results revealed that the arsenic in realgar accumulated in the brain and led to neurobehavioral abnormalities in the rats. We demonstrated that arsenic in realgar-induced high expression of UBXD8 promoted the translocation of DRP1 to the mitochondria, where it underwent phosphorylation, which led to the over-fission of the mitochondria and mitochondria-mediated apoptosis. Moreover, the over-fission of the mitochondria activates mitophagy, which is self-protective but only partially alleviates apoptosis and mitochondria dysfunction. Our findings revealed the crosstalk between mitochondrial fission and mitophagy in realgar-induced neurotoxicity. These results highlight the role of the transposition of DRP1 by UBXD8 in realgar-induced mitochondrial dysfunction and provide new ideas and data for the study of the mechanism of realgar-induced neurotoxicity.

The Protective Effect of Ellagic Acid and Its Metabolites Against Organ Injuries: A Mitochondrial Perspective

Mitochondria are essential for maintaining health, and dysfunction of them leads to various diseases. Their role is not limited to energy production but serves multiple mechanisms varying from calcium hemostasis, reactive oxygen species production, and regulation of apoptotic cell death. In recent years, several strategies have been developed to preserve mitochondria. Ellagic acid (EA) is a polyphenol extracted from many plants. The intestinal microflora converts EA to urolithins with high bioavailability. EA and urolithins exhibit mitochondrial-protective effects by regulating mitochondrial complexes, sirtuins, mitophagy, and mitochondrial antioxidant enzymes. This review highlights the mito-protective effects of EA and urolithins on mitochondrial injuries induced by various drugs and toxic compounds.

Xin-Ji-Er-Kang balances mitochondrial fusion and fission to protect cardiomyocytes in mice with heart failure by regulating the ERα/SIRT3 pathway

BACKGROUND

Mitochondrial dynamics imbalance is an essential pathological mechanism in heart failure (HF). The Chinese herbal formula Xin-Ji-Er-Kang (XJEK) has demonstrated good therapeutic effects in various cardiovascular disease models. However, whether XJEK treats HF by regulating mitochondrial dynamics homeostasis and its specific molecular mechanisms remain elusive.

PURPOSE

To investigate the effect of XJEK on restoring the disrupted mitochondrial dynamics homeostasis in HF and elucidate the potential regulatory mechanism.

STUDY-DESIGN/METHODS

A mouse model of myocardial ischemia-reperfusion (MIR)-induced HF was established to assess the cardioprotection of XJEK. Subsequently, network pharmacology was employed to predict the mechanism by which XJEK treated HF. Moreover, gene silencing was employed to explore the potential mechanisms behind the cardioprotective effects of XJEK in AC16 cells subjected to hypoxia/reoxygenation (H/R).

RESULTS

XJEK treatment significantly attenuated myocardial fibrosis and ameliorated ventricular remodeling in post-MIR-induced HF mice. Network pharmacology analysis identified the estrogen receptor α (ERα) as a key regulator of XJEK-mediated cardioprotection. XJEK disordered mitochondrial dynamics in the hearts of MIR-induced HF mice. In addition, XJEK restored mitochondrial fusion-fission imbalance and facilitated ERα nuclear translocation to up-regulate sirtuin 3 (SIRT3) expression in the hearts of MIR-induced HF mice and H/R-induced AC16 cells. Notably, ERα depletion in cardiomyocytes completely abrogated the cardioprotective effects of XJEK.

CONCLUSION

XJEK safeguards the hearts in mice with MIR-induced HF by facilitating ERα nuclear translocation to up-regulate SIRT3 expression to rescue the mitochondrial fusion-fission imbalance. This study establishes a new theoretical basis for treating HF with XJEK.

Inhibition of ERK1/2 mediated activation of Drp1 alleviates intervertebral disc degeneration via suppressing pyroptosis and apoptosis in nucleus pulposus cells

Objective

Dynamin-related protein 1 (Drp1) plays a crucial role in various inflammatory and degenerative diseases, yet its involvement in intervertebral disc degeneration (IVDD) remains poorly understood. This study aims to elucidate the mechanism by which Drp1 contributes to IVDD and to identify the efficacy of the Drp1 inhibitor Mdivi-1 on IVDD.

Methods

Tert-butyl hydroperoxide (TBHP) is utilized to induce an oxidative stress microenvironment in vitro. In vivo, IVDD model is constructed in 8-week old rats through puncture operation. The therapeutic effect of Mdivi-1 is evaluated through X-ray, MRI and histological analysis. A comprehensive set of experiments, including single-cell sequencing analysis, western blot, flow cytometry and immunofluorescence staining, are conducted to investigate the role and underlying mechanisms of Drp1 in vitro.

Results

Our study demonstrates that the expression of Drp1 and phosphorylated Drp1 (p-Drp1) are up-regulated in degenerative nucleus pulposus cells (NPCs), which are accompanied with increased pyroptosis and apoptosis. In vivo, both si-Drp1-mediated Drp1 knockdown and the pharmacological inhibitor Mdivi-1 alleviate puncture-induced IVDD in rats. In vitro, si-Drp1 or Mdivi-1 inhibits mitochondria-dependent apoptosis and pyroptosis triggered by TBHP. Mechanistically, Mdivi-1 reduces p-Drp1 levels, inhibits excessive mitochondrial fission, and mitigates mitochondrial dysfunction. Drp1 phosphorylation-based Drp1 mitochondrial translocation and subsequent apoptosis and pyroptosis are regulated by ERK1/2 phosphorylation in NPCs under oxidative stress condition.

Conclusion

This study highlights the involvement of Drp1 in the pathological progression of degenerative NPCs in IVDD, which is regulated by ERK1/2. Pharmacological inhibition of Drp1 with Mdivi-1 protects NPCs by promoting mitochondrial function and attenuating apoptosis and pyroptosis. These findings suggest that Mdivi-1 is a promising therapeutic candidate for IVDD treatment.

Translational Potential

By offering experimental evidence on the role and mechanism of Drp1 in IVDD, this study underscores the potential of Mdivi-1 as a therapeutic strategy for IVDD.

Aβ -induced excessive mitochondrial fission drives type H blood vessels injury to aggravate bone loss in APP/PS1 mice with Alzheimer's diseases

Alzheimer's diseases (AD) patients suffer from more serious bone loss than cognitively normal subjects at the same age. Type H blood vessels were tightly associated with bone homeostasis. However, few studies have concentrated on bone vascular alteration and its role in AD-related bone loss. In this study, APP/PS1 mice (4- and 8-month-old) and age-matched wild-type mice were used to assess the bone vascular alteration and its role in AD-related bone loss. Transmission electron microscopy, immunofluorescence staining and iGPS 1.0 software database were utilized to investigate the molecular mechanism. Mitochondrial division inhibitor (Mdivi-1) and GSK-3β inhibitor (LiCl) were used to rescue type H blood vessels injury and verify the molecular mechanism. Our results revealed that APP/PS1 mice exhibited more serious bone blood vessels injury and bone loss during ageing. The bone blood vessel injury, especially in type H blood vessels, was accompanied by impaired vascularized osteogenesis in APP/PS1 mice. Further exploration indicated that beta-amyloid (Aβ) promoted the apoptosis of vascular endothelial cells (ECs) and resulted in type H blood vessels injury. Mechanistically, Aβ-induced excessive mitochondrial fission was found to be essential for the apoptosis of ECs. GSK-3β was identified as a key regulatory target of Aβ-induced excessive mitochondrial fission and bone loss. The findings delineated that Aβ-induced excessive mitochondrial fission drives type H blood vessels injury, leading to aggravate bone loss in APP/PS1 mice and GSK-3β inhibitor emerges as a potential therapeutic strategy.

The Cardiovascular Protective Function of Natural Compounds Through AMPK/SIRT1/PGC-1α Signaling Pathway

Cardiovascular disease (CVD) poses a major risk to human health and exert a heavy burden on individuals, society, and healthcare systems. Therefore, it is critical to identify CVD's underlying mechanism(s) and target them using effective agents. Natural compounds have shown promise as antioxidants with cardioprotective functions against CVD injuries due to their antioxidative solid capacity and high safety profile. Several CVDs, such as heart failure, ischemia/reperfusion, atherosclerosis, and cardiomyopathies, are closely linked to mitochondrial dysfunction. It is well established that activating the AMPK/SIRT1/PGC-1α pathway during CVD promotes mitochondrial function. Therefore, targeting the AMPK/SIRT1/PGC-1α pathway provides a foundation for novel therapeutic strategies to combat CVD. A key goal of our search was to find natural compounds that target this biological pathway and have beneficial effects on CVD.

Melatonin effect on breast and ovarian cancers by targeting the PI3K/Akt/mTOR pathway

Melatonin, the hormone of the pineal gland, possesses a range of physiological functions, and recently, its anticancer effect has become more apparent. A more thorough understanding of molecular alterations in the components of several signaling pathways as new targets for cancer therapy is needed because of current innate restrictions such as drug toxicity, side effects, and acquired or de novo resistance. The PI3K/Akt/mTOR pathway is overactivated in many solid tumors, such as breast and ovarian cancers. This pathway in normal cells is essential for growth, proliferation, and survival. However, it is an undesirable characteristic in malignant cells. We have reviewed multiple studies about the effect of melatonin on breast and ovarian cancer, focusing on the PI3K/Akt/mTOR pathway. Melatonin exerts its inhibitory effects via several mechanisms. A: Downregulation of downstream or upstream components of the signaling pathway such as phosphatase and tensin homolog (PTEN), phosphatidylinositol (3,4,5)-trisphosphate kinase (PI3K), p-PI3K, Akt, p-Akt, mammalian target of rapamycin (mTOR), and mTOR complex1 (mTORC1). B: Apoptosis induction by decreasing MDM2 expression, a downstream target of Akt, and mTOR, which leads to Bad activation in addition to Bcl-XL and p53 inhibition. C: Induction of autophagy in cancer cells via activating ULK1 after mTOR inhibition, resulting in Beclin-1 phosphorylation. Beclin-1 with AMBRA1 and VPS34 promotes PI3K complex I activity and autophagy in cancer cells. The PI3K/Akt/mTOR pathway overlaps with other intracellular signaling pathways and components such as AMP-activated protein kinase (AMPK), Wnt/β-catenin, mitogen-activated protein kinase (MAPK), and other similar pathways. Cancer therapy can benefit from understanding how these pathways interact and how melatonin affects these pathways.

Isoliquiritigenin alleviates cerebral ischemia-reperfusion injury by reducing oxidative stress and ameliorating mitochondrial dysfunction via activating the Nrf2 pathway

Cerebral ischemia-reperfusion injury (CIRI) refers to a secondary brain injury that occurs when blood supply is restored to ischemic brain tissue and is one of the leading causes of adult disability and mortality. Multiple pathological mechanisms are involved in the progression of CIRI, including neuronal oxidative stress and mitochondrial dysfunction. Isoliquiritigenin (ISL) has been preliminarily reported to have potential neuroprotective effects on rats subjected to cerebral ischemic insult. However, the protective mechanisms of ISL have not been elucidated. This study aims to further investigate the effects of ISL-mediated neuroprotection and elucidate the underlying molecular mechanism. The findings indicate that ISL treatment significantly alleviated middle cerebral artery occlusion (MCAO)-induced cerebral infarction, neurological deficits, histopathological damage, and neuronal apoptosis in mice. In vitro, ISL effectively mitigated the reduction of cell viability, Na+-K+-ATPase, and MnSOD activities, as well as the degree of DNA damage induced by oxygen-glucose deprivation (OGD) injury in PC12 cells. Mechanistic studies revealed that administration of ISL evidently improved redox homeostasis and restored mitochondrial function via inhibiting oxidative stress injury and ameliorating mitochondrial biogenesis, mitochondrial fusion-fission balance, and mitophagy. Moreover, ISL facilitated the dissociation of Keap1/Nrf2, enhanced the nuclear transfer of Nrf2, and promoted the binding activity of Nrf2 with ARE. Finally, ISL obviously inhibited neuronal apoptosis by activating the Nrf2 pathway and ameliorating mitochondrial dysfunction in mice. Nevertheless, Nrf2 inhibitor brusatol reversed the mitochondrial protective properties and anti-apoptotic effects of ISL both in vivo and in vitro. Overall, our findings revealed that ISL exhibited a profound neuroprotective effect on mice following CIRI insult by reducing oxidative stress and ameliorating mitochondrial dysfunction, which was closely related to the activation of the Nrf2 pathway.

The Protective Effects of Syringic Acid on Bisphenol A-Induced Neurotoxicity Possibly Through AMPK/PGC-1α/Fndc5 and CREB/BDNF Signaling Pathways

Bisphenol A (BPA), an endocrine disruptor, is commonly used to produce epoxy resins and polycarbonate plastics. Continuous exposure to BPA may contribute to the development of diseases in humans and seriously affect their health. Previous research suggests a significant relationship between the increased incidence of neurological diseases and the level of BPA in the living environment. Syringic acid (SA), a natural derivative of gallic acid, has recently considered much attention due to neuromodulator activity and its anti-oxidant, anti-apoptotic, and anti-inflammatory effects. Therefore, in this study, we aimed to investigate the effects of SA on oxidative stress, apoptosis, memory and locomotor disorders, and mitochondrial function, and to identify the mechanisms related to Alzheimer's disease (AD) in the brain of rats receiving high doses of BPA. For this purpose, male Wistar rats received BPA (50, 100, and 200 mg/kg) and SA (50 mg/kg) for 21 days. The results showed that BPA exposure significantly altered the rats' neurobehavioral responses. Additionally, BPA, by increasing the level of ROS, and MDA level, increased the level of oxidative stress while reducing the level of antioxidant enzymes, such as SOD, CAT, GPx, and mitochondrial GSH. The administration of BPA at 200 mg/kg significantly decreased the expression of ERRα, TFAM, irisin, PGC-1α, Bcl-2, and FNDC5, while it increased the expression of TrkB, cytochrome C, caspase 3, and Bax. Moreover, the Western blotting results showed that BPA increased the levels of P-AMPK, GSK3b, p-tau, and Aβ, while it decreased the levels of PKA, P-PKA, Akt, BDNF, CREB, P-CREB, and PI3K. Meanwhile, SA at 50 mg/kg reversed the behavioral, biochemical, and molecular changes induced by high doses of BPA. Overall, BPA could lead to the development of AD by affecting the mitochondria-dependent apoptosis pathway, as well as AMPK/PGC-1α/FNDC5 and CREB/BDNF/TrkB signaling pathways, and finally, by increasing the expression of tau and Aβ proteins. In conclusion, SA, as an antioxidant, significantly reduced the toxicity of BPA.

Melatonin regulates mitochondrial dynamics and mitophagy: Cardiovascular protection

Despite extensive progress in the knowledge and understanding of cardiovascular diseases and significant advances in pharmacological treatments and procedural interventions, cardiovascular diseases (CVD) remain the leading cause of death globally. Mitochondrial dynamics refers to the repetitive cycle of fission and fusion of the mitochondrial network. Fission and fusion balance regulate mitochondrial shape and influence physiology, quality and homeostasis. Mitophagy is a process that eliminates aberrant mitochondria. Melatonin (Mel) is a pineal-synthesized hormone with a range of pharmacological properties. Numerous nonclinical trials have demonstrated that Mel provides cardioprotection against ischemia/reperfusion, cardiomyopathies, atherosclerosis and cardiotoxicity. Recently, interest has grown in how mitochondrial dynamics contribute to melatonin cardioprotective effects. This review assesses the literature on the protective effects of Mel against CVD via the regulation of mitochondrial dynamics and mitophagy in both in-vivo and in-vitro studies. The signalling pathways underlying its cardioprotective effects were reviewed. Mel modulated mitochondrial dynamics and mitophagy proteins by upregulation of mitofusin, inhibition of DRP1 and regulation of mitophagy-related proteins. The evidence supports a significant role of Mel in mitochondrial dynamics and mitophagy quality control in CVD.

QiDongNing induces lung cancer cell apoptosis via triggering P53/DRP1-mediated mitochondrial fission

Non-small-cell lung cancer (NSCLC) is a major cause of worldwide cancer death, posing a challenge for effective treatment. Our previous findings showed that Chinese herbal medicine (CHM) QiDongNing (QDN) could upregulate the expression of p53 and trigger cell apoptosis in NSCLC. Here, our objective was to investigate the mechanisms of QDN-induced apoptosis enhancement. We chose A549 and NCI-H460 cells for validation in vitro, and LLC cells were applied to form a subcutaneous transplantation tumour model for validation in more depth. Our findings indicated that QDN inhibited multiple biological behaviours, including cell proliferation, cloning, migration, invasion and induction of apoptosis. We further discovered that QDN increased the pro-apoptotic BAX while inhibiting the anti-apoptotic Bcl2. QDN therapy led to a decline in adenosine triphosphate (ATP) and a rise in reactive oxygen species (ROS). Furthermore, QDN elevated the levels of the tumour suppressor p53 and the mitochondrial division factor DRP1 and FIS1, and decreased the mitochondrial fusion molecules MFN1, MFN2, and OPA1. The results were further verified by rescue experiments, the p53 inhibitor Pifithrin-α and the mitochondrial division inhibitor Mdivi1 partially inhibited QDN-induced apoptosis and mitochondrial dysfunction, whereas overexpression of p53 rather increased the efficacy of the therapy. Additionally, QDN inhibited tumour growth with acceptable safety in vivo. In conclusion, QDN induced apoptosis via triggering p53/DRP1-mediated mitochondrial fission in NSCLC cells.

Current understanding of plant-derived exosome-like nanoparticles in regulating the inflammatory response and immune system microenvironment

Natural compounds are widely used to prevent and treat various diseases due to their antioxidant and anti-inflammatory effects. As a kind of promising natural compound, plant-derived exosome-like nanoparticles (PELNs) are extracted from multivesicular bodies of various edible plants, including vegetables, foods, and fruits, and mainly regulate the cellular immune response to pathogen attacks. Moreover, PELNs could remarkably interfere with the dynamic imbalance between pro-inflammatory and anti-inflammatory effects, facilitating to maintain the homeostasis of cellular immune microenvironment. PELNs may serve as a better alternative to animal-derived exosomes (ADEs) owing to their widespread sources, cost-effectiveness, and easy accessibility. PELNs can mediate interspecies communication by transferring various cargoes such as proteins, lipids, and nucleic acids from plant cells to mammalian cells. This review summarizes the biogenesis, composition, and classification of exosomes; the common separation, purification, and characterization methods of PELNs, the potential advantages of PELNs over ADEs; and the anti-inflammatory and immunomodulatory functions of PELNs in various diseases including colitis, cancer, and inflammation-associated metabolic diseases. Additionally, the future perspectives of PELNs and the challenges associated with their clinical application are discussed.

Necroptosis signaling and mitochondrial dysfunction cross-talking facilitate cell death mediated by chelerythrine in glioma

Glioma is the most common primary malignant brain tumor with poor survival and limited therapeutic options. Chelerythrine (CHE), a natural benzophenanthridine alkaloid, has been reported to exhibit the anti-tumor effects in a variety of cancer cells. However, the molecular target and the signaling process of CHE in glioma remain elusive. Here we investigated the underlying mechanisms of CHE in glioma cell lines and glioma xenograft mice model. Our results found that CHE-induced cell death is associated with RIP1/RIP3-dependent necroptosis rather than apoptotic cell death in glioma cells at the early time. Mechanism investigation revealed the cross-talking between necroptosis and mitochondria dysfunction that CHE triggered generation of mitochondrial ROS, mitochondrial depolarization, reduction of ATP level and mitochondrial fragmentation, which was the important trigger for RIP1-dependent necroptosis activation. Meanwhile, PINK1 and parkin-dependent mitophagy promoted clearance of impaired mitochondria in CHE-incubated glioma cells, and inhibition of mitophagy with CQ selectively enhanced CHE-induced necroptosis. Furthermore, early cytosolic calcium from the influx of extracellular Ca²⁺ induced by CHE acted as important "priming signals" for impairment of mitochondrial dysfunction and necroptosis. Suppression of mitochondrial ROS contributed to interrupting positive feedback between mitochondrial damage and RIPK1/RIPK3 necrosome. Lastly, subcutaneous tumor growth in U87 xenograft was suppressed by CHE without significant body weight loss and multi-organ toxicities. In summary, the present study helped to elucidate necroptosis was induced by CHE via mtROS-mediated formation of the RIP1-RIP3-Drp1 complex that promoted Drp1 mitochondrial translocation to enhance necroptosis. Our findings indicated that CHE could potentially be further developed as a novel therapeutic strategy for treatment of glioma.