Mitophagy-related Protein Research Articles

BNIP3 Downregulation Ameliorates Muscle Atrophy in Cancer Cachexia.

Cancer cachexia is a complex syndrome affecting most cancer patients and is directly responsible for about 20% of cancer-related deaths. Previous studies showed muscle proteolysis hyper-activation and mitophagy induction in tumor-bearing animals. While basal mitophagy is required for maintaining muscle mass and quality, excessive mitophagy promotes uncontrolled protein degradation, muscle loss and impaired function. BNIP3, a key mitophagy-related protein, is significantly increased in the muscles of both mice and human cancer hosts. This study aimed to define the potential of mitigating mitophagy via BNIP3 downregulation in preserving mitochondrial integrity, counteracting skeletal muscle loss in experimental cancer cachexia. Two in vivo gene delivery methods were performed to knock down muscle BNIP3: electroporation of a BNIP3-specific shRNA expression vector or adenovirus injection. The electroporation effectively reduced muscle BNIP3 in healthy mice but was ineffective in C26 tumor-bearing mice. In contrast, adenovirus-mediated BNIP3 knockdown successfully decreased BNIP3 levels also in tumor hosts. Although BNIP3 knockdown did not impact overall on body or muscle mass, it improved muscle fiber size in C26-bearing miceh2, suggesting partial prevention of muscle atrophy. Mitochondrial respiratory chain complexes (OxPhos) and TOM20 protein levels were consistently rescued, indicating improvements in mitochondrial mass, while H2O2 levels were unchanged among the groups, suggesting that BNIP3 downregulation does not impair the endogenous control of oxidative balance. These findings suggest that a fine balance between mitochondrial disposal and biogenesis is fundamental for preserving muscle homeostasis and highlight a potential role for BNIP3 modulation against cancer-induced muscle wasting.

Mitochondrial Alterations in Alzheimer's Disease: Insight from the 5xFAD Mouse Model.

Mitochondrial dysfunction is increasingly recognized as a key factor in Alzheimer's disease (AD) pathogenesis, but the precise relationship between mitochondrial dynamics and proteinopathies in AD remains unclear. This study investigates the role of mitochondrial dynamics and function in the hippocampal tissue and peripheral blood mononuclear cells (PBMCs) of 5xFAD transgenic mice, as a model of AD. The levels of mitochondrial fusion proteins OPA1 and MFN2 and fission proteins DRP1 and phospho-DRP1 (S616) at 3, 6, and 9months of age were assessed. Western blot analysis revealed significantly lower levels of OPA1 and MFN2 in the hippocampus of 6- and 9-month-old transgenic (TG) 5xFAD mice compared to controls (CTR), while DRP1 and pDRP1 levels were increased in 9-month-old TG mice. Additionally, MFN2 were decreased inthe PBMCs of 9-month-old TGmice,indicatingsystemic mitochondrial alterations. Ultrastructural analysis of hippocampal tissues showed substantial alterations in mitochondrial morphology, including abnormalities in size and shape, a preponderance of teardrop-shaped mitochondria, and alterations in the somatic mitochondria-ER complex. Notably,mitochondria-associated ER contact sites were more distant in TG mice, suggesting functional impairments. Flow cytometric measurements demonstrated decreased mitochondrial membrane potential and mass, along with increased superoxide production, in the PBMCs of TG mice, particularly at 9months, highlighting compromised mitochondrial function. Levels of keymitochondrial proteins including VDAC, TOM2O, and mitophagy-related protein PINK1 levels altered in both central andperipheral tissue of TG mice. These findings suggest that mitochondrial dysfunction and altered dynamics are early events in AD development in 5xFAD mice, manifesting in both central and peripheral tissues, and support the notion that mitochondrial abnormalities are an integral component of AD pathology. These insights might lead to the development of targeted therapies that modulate mitochondrial dynamics and function to mitigate AD progression.

Cyclovirobuxine D inhibits triple-negative breast cancer via YAP/TAZ suppression and activation of the FOXO3a/PINK1-Parkin pathway-induced mitophagy

BackgroundTriple-negative breast cancer (TNBC) is characterized by its rapid progression and aggressive nature, with limited effective therapeutic interventions currently available. Cyclovirobuxine D (CVB-D), a natural alkaloid extracted from the traditional Chinese herb Buxus sinica, is renowned for its cardioprotective and anti-ischemic effects, demonstrating notable anti-cancer properties. Nevertheless, the anti-tumor effects of CVB-D on TNBC remain unverified. PurposeThis study seeks to investigate the effects of CVB-D on TNBC and to uncover the underlying mechanisms. Study DesignNetwork pharmacology, SPR, DSF, and cell-based functional assays were conducted on TNBC cells to assess the impact of CVB-D. Findings were further corroborated using xenograft mouse models. MethodsCell Counting Kit-8, 5-Ethynyl-2′-deoxyuridine, transwell assays, flow cytometry, wound healing assays, immunofluorescence, and immunoblotting were employed to evaluate CVB-D's influence on TNBC cell lines. SPR, DSF and molecular docking techniques were utilized to assess the binding affinity of CVB-D to Yes-associated protein (YAP). The interaction between CVB-D and autophagy/mitophagy was further analyzed through plasmid transient transfection, JC-1 assay, TUNEL assay, and the use of autophagy inhibitors. The anti-TNBC mechanism of CVB-D was elucidated by overexpressing YAP in MDA-MB-231 cells. Additionally, the in vivo efficacy and safety of CVB-D were assessed in a xenograft mouse model. ResultsIn vitro analyses revealed that CVB-D effectively suppressed G1 phase arrest and inhibited TNBC cell proliferation. Moreover, CVB-D induced mitochondrial-dependent apoptosis and reduced cell migration by antagonizing epithelial-mesenchymal transition. Mechanistically, CVB-D exerted its anti-cancer effects by directly binding to YAP, thereby inhibiting the nuclear translocation of YAP/TAZ and suppressing the transcription of downstream oncogenic target genes. Furthermore, CVB-D triggered excessive mitophagy by activating the FOXO3a/PINK1-Parkin axis, promoting apoptosis and leading to mitochondrial dysfunction in TNBC cells. Elevated YAP expression counteracted the effects of CVB-D on TNBC, including the suppression of mitophagy-related protein expression induced by CVB-D, suggesting that YAP modulates mitophagy through the FOXO3a/PINK1-Parkin axis. The anti-tumor efficacy of CVB-D and its underlying mechanisms were further substantiated using a subcutaneous xenograft model. ConclusionsThis study is the first to demonstrate that CVB-D can directly bind to the YAP target, proposing a novel therapeutic strategy for TNBC. CVB-D may serve both as a YAP/TAZ inhibitor and as an activator of the FOXO3a/PINK1-Parkin axis, leading to excessive mitophagy.

Intermittent Hypoxia Impairs Cognitive Function and Promotes Mitophagy and Lysophagy in Obstructive Sleep Apnea-Hypopnea Syndrome Rat Model.

Autophagy regulates intermittent hypoxia (IH)-induced obstructive sleep apnea-hypopnea syndrome (OSAHS). We investigated the effects of IH and its withdrawal on cognitive function, autophagy, and lysophagy in OSAHS. An OSAHS rat model was established, and rats were divided into five groups: normoxia control, IH-4w (4-week IH), IH-6w (6-week IH), IH-8w (8-week IH), and IH-8w + 4w (8-week IH and 4-week normoxia). The cognitive behavior; mitochondrial and lysosomal morphology of the hippocampal tissue; mitochondrial respiratory function, permeability, and membrane potential; lysosomal function; autophagy- and lysophagy-related protein levels; and hypoxia-associated autophagy gene expression in rats were assessed. The cognitive function of rats in the IH-4w, IH-6w, and IH-8w groups was significantly impaired. In IH-8w cells, mitochondrial function was damaged with swollen morphology and decreased quantity, respiration, permeability, and membrane potential, along with significantly increased mitophagy-related protein ATG5 and LC3II/LC3 levels and decreased p62 levels. Expression of hypoxia-associated autophagy genes Becn1, Hif1, Bnip3, Bnip3l, and Fundc1 was significantly higher in the IH-8w group. Significantly increased LAMP2, CTSB, and ACP2 levels in IH-8w cells further indicated impaired lysosomal function. Lysophagy-related protein LAMP1, LC3II/LC3I, and TFEB levels were significantly increased in the IH-8w group, whereas p62 level was significantly decreased. The above listed evidence indicated damage to the mitochondria and lysosomes, as well as stimulation of mitophagy and lysophagy in IH-treatment OSAHS rat model. After withdrawing IH and culturing for 4weeks in normal conditions, the cognitive function of rats improved, and mitophagy and lysophagy decreased. Our findings indicate that IH impairs cognitive function and promotes mitophagy and lysophagy in an OSAHS rat model, and IH withdrawal recovered the above effects.

Enhancing terminal erythroid differentiation in human embryonic stem cells through TRIB3 overexpression

Tribbles pseudokinase 3 (TRIB3) expression significantly increases during terminal erythropoiesis in vivo. However, we found that TRIB3 expression remained relatively low during human embryonic stem cell (hESC) erythropoiesis, particularly in the late stage, where it is typically active. TRIB3 was expressed in megakaryocyte-erythrocyte progenitor cells and its low expression was necessary for megakaryocyte differentiation. Thus, we proposed that the high expression during late stage of erythropoiesis could be the clue for promotion of maturation of hESC-derived erythroid cells. To our knowledge, the role of TRIB3 in the late stage of erythropoiesis remains ambiguous. To address this, we generated inducible TRIB3 overexpression hESCs, named TRIB3tet-on OE H9, based on a Tet-On system. Then, we analyzed hemoglobin expression, condensed chromosomes, organelle clearance, and enucleation with or without doxycycline treatment. TRIB3tet-on OE H9 cells generated erythrocytes with a high proportion of orthochromatic erythroblast in flow cytometry, enhanced hemoglobin and related protein expression in Western blot, decreased nuclear area size, promoted enucleation rate, decreased lysosome and mitochondria number, more colocalization of LC3 with LAMP1 (lysosome marker) and TOM20 (mitochondria marker) and up-regulated mitophagy-related protein expression after treatment with 2 μg/mL doxycycline. Our results showed that TRIB3 overexpression during terminal erythropoiesis may promote the maturation of erythroid cells. Therefore, our study delineates the role of TRIB3 in terminal erythropoiesis, and reveals TRIB3 as a key regulator of UPS and downstream mitophagy by ensuring appropriate mitochondrial clearance during the compaction of chromatin.

Acupotomy alleviates knee osteoarthritis in rabbit by regulating chondrocyte mitophagy Pink1-Parkin pathway.

To investigate the effect of acupotomy, on mitophagy and the Pink1-Parkin pathway in chondrocytes from rabbits with knee osteoarthritis (KOA). A KOA model was established via the modified Videman method. Rabbits were randomly divided into a control group (CON), KOA group and KOA + acupotomy group (Acu). Rabbits in the acupotomy group were subjected to acupotomy for 4 weeks after model establishment. The behavior of the rabbits before and after intervention was recorded. Cartilage degeneration was evaluated by optical microscopy and fluorescence microscopy. The level of mitophagy was evaluated by transmission electron microscopy, immunofluorescence and enzyme-linked immunosorbent assay (ELISA). The expression of phosphatase and tensin homolog (PTEN)-induced kinase 1 (Pink1)-Parkin mitophagy pathway components was evaluated by immunofluorescence, Western blotting and real-time polymerase chain reaction. In rabbits with KOA, joint pain, mobility disorders and cartilage degeneration were observed, the Mankin score was increased, collagen type Ⅱ (Col-Ⅱ) expression was significantly decreased, mitophagy was inhibited, mitochondrial function was impaired, and factors associated with the Pink1-Parkin pathway were inhibited. Acupotomy regulated the expression of Pink1-Parkin pathway-related proteins, the mitophagy-related protein microtubule-associated protein-1 light chain-3, the translocase of the outer membrane, and the inner mitochondrial membrane 23; increased the colocalization of mitochondria and autophagosomes; promoted the removal of damaged mitochondria; restored mitochondrial adenosine-triphosphate (ATP) production; and alleviated cartilage degeneration in rabbits with KOA. Acupotomy played a role in alleviating KOA in rabbits by activating mitophagy in chondrocytes via the regulation of proteins that are related to the Pink1-Parkin pathway.

Formoterol Acting via β2-Adrenoreceptor Restores Mitochondrial Dysfunction Caused by Parkinson's Disease-Related UQCRC1 Mutation and Improves Mitochondrial Homeostasis Including Dynamic and Transport.

Formoterol, a β2-adrenergic receptor (β2AR) agonist, shows promise in various diseases, but its effectiveness in Parkinson's disease (PD) is debated, with unclear regulation of mitochondrial homeostasis. This study employed a cell model featuring mitochondrial ubiquinol-cytochrome c reductase core protein 1 (UQCRC1) variants associated with familial parkinsonism, demonstrating mitochondrial dysfunction and dynamic imbalance, exploring the therapeutic effects and underlying mechanisms of formoterol. Results revealed that 24-h formoterol treatment enhanced cell proliferation, viability, and neuroprotection against oxidative stress. Mitochondrial function, encompassing DNA copy number, repatriation, and complex III-linked respiration, was comprehensively restored, along with the dynamic rebalance of fusion/fission events. Formoterol reduced extensive hypertubulation, in contrast to mitophagy, by significantly upregulating protein Drp-1, in contrast to fusion protein Mfn2, mitophagy-related protein Parkin. The upstream mechanism involved the restoration of ERK signaling and the inhibition of Akt overactivity, contingent on the activation of β2-adrenergic receptors. Formoterol additionally aided in segregating healthy mitochondria for distribution and transport, therefore normalizing mitochondrial arrangement in mutant cells. This study provides preliminary evidence that formoterol offers neuroprotection, acting as a mitochondrial dynamic balance regulator, making it a promising therapeutic candidate for PD.

Atmospheric fine particulate matter (PM2.5) induces pulmonary fibrosis by regulating different cell fates via autophagy

The presence of respiratory diseases demonstrates a positive correlation with atmospheric fine particulate matter (PM2.5) exposure. The respiratory system is the main target organ affected by PM2.5, and exposure to PM2.5 elevates the likelihood of developing pulmonary fibrosis (PF). In this study, lung epithelial cell (BEAS-2B) and fibroblast (NIH-3T3) were used as in vitro exposure models to explore the mechanisms of PF. PM2.5 exposure caused mitochondrial damage in BEAS-2B cells and increased a fibrotic phenotype in NIH-3T3 cells. Epithelial cells and fibroblasts have different fates after PM2.5 exposure due to their different sensitivities to trigger autophagy. Exposure to PM2.5 inhibits mitophagy in BEAS-2B cells, which hinders the removal of damaged mitochondria and triggers cell death. In this process, the nuclear retention of the mitophagy-related protein Parkin prevents it from being recruited to mitochondria, resulting in mitophagy inhibition. In contrast, fibroblasts exhibit increased levels of autophagy, which may isolate PM2.5 and cause abnormal fibroblast proliferation and migration. Fibrotic phenotypes such as collagen deposition and increased α-actin also appear in fibroblasts. Our results identify PM2.5 as a trigger of PF and delineate the molecular mechanism of autophagy in PM2.5 induced PF, which provides new insights into the pulmonary injury.

Oxidative stress suppresses PHB2-mediated mitophagy in β-cells via the Nrf2/PHB2 pathway.

Mitochondrial damage caused by oxidative stress is a main driver of pancreatic β-cell dysfunction in the pathogenesis of type 2 diabetes mellitus. Prohibitin2 (PHB2) is a vital inner mitochondrial membrane protein that participates in mitophagy to remove the damaged mitochondria. This study aimed to investigate the role and mechanisms of PHB2-mediated mitophagy in oxidative stress-induced pancreatic β-cell dysfunction. PHB2 and mitophagy-related protein expression were analyzed by real-time polymerase chain reaction and western blotting in RINm5F cells treated with H2O2 and islets of diabetic rats. Mitophagy was observed by mitochondrial and lysosome colocalization. RINm5F cells were transfected by phb2 siRNA or overexpression plasmid to explore the role of PHB2 in mitophagy of RINm5F cells. The mechanism of Nrf2 regulating PHB2 was explored by Nrf2 inhibitor and agonist. The expression of PHB2, mitophagy related protein PINK1, and Parkin were decreased in RINm5F cells incubated with H2O2 and in islets of diabetic rats. Overexpression of PHB2 protected β-cells from oxidative stress by promoting mitophagy and inhibiting cell apoptosis, whereas transfection with PHB2 siRNA suppressed mitophagy. Furthermore, PHB2-mediated mitophagy induced by oxidative stress was through the Nrf2/PHB2 pathway in β-cells. Antioxidant NAC alleviated oxidative stress injury by promoting PHB2-mediated mitophagy. Our study suggested that PHB2-mediated mitophagy can protect β-cells from apoptosis via the Nrf2/PHB2 pathway under oxidative stress. Antioxidants may protect β-cell from oxidative stress by prompting PHB2-mediated mitophagy. PHB2-mediated mitophagy as a potential mechanism takes part in the oxidative stress induced β-cell injury.

Synthesis and anticancer mechanisms of four novel platinum(II) 4'-substituted-2,2':6',2''-terpyridine complexes.

Mitophagy, a selective autophagic process, has emerged as a pathway involved in degrading dysfunctional mitochondria. Herein, new platinum(II)-based chemotherapeutics with mitophagy-targeting properties are proposed. Four novel binuclear anticancer Pt(II) complexes with 4'-substituted-2,2':6',2''-terpyridine derivatives (tpy1-tpy4), i.e., [Pt2(tpy1)(DMSO)2Cl4]·CH3OH (tpy1Pt), [Pt(tpy2)Cl][Pt(DMSO)Cl3]·CH3COCH3 (tpy2Pt), [Pt(tpy3)Cl][Pt(DMSO)Cl3] (tpy3Pt), and [Pt(tpy4)Cl]Cl·CH3OH (tpy4Pt), were designed and prepared. Moreover, their potential antitumor mechanism was studied. Tpy1Pt-tpy4Pt exhibited more selective cytotoxicity against cisplatin-resistant SK-OV-3/DDP (SKO3cisR) cancer cells compared with those against ovarian SK-OV-3 (SKO3) cancer cells and normal HL-7702 liver (H702) cells. This selective cytotoxicity of Tpy1Pt-tpy4Pt was better than that of its ligands (i.e., tpy1-tpy4), the clinical drug cisplatin, and cis-Pt(DMSO)2Cl2. The results of various experiments indicated that tpy1Pt and tpy2Pt kill SKO3cisR cancer cells via a mitophagy pathway, which involves the disruption of the mitophagy-related protein expression, dissipation of the mitochondrial membrane potential, elevation of the [Ca2+] and reactive oxygen species levels, promotion of mitochondrial DNA damage, and reduction in the adenosine triphosphate and mitochondrial respiratory chain levels. Furthermore, in vivo experiments indicated that the dinuclear anticancer Pt(II) coordination compound (tpy1Pt) has remarkable therapeutic efficiency (ca. 52.4%) and almost no toxicity. Therefore, the new 4'-substituted-2,2':6',2''-terpyridine Pt(II) coordination compound (tpy1Pt) is a potential candidate for next-generation mitophagy-targeting dinuclear Pt(II)-based anticancer drugs.

TNF-α-Induced KAT2A Impedes BMMSC Quiescence by Mediating Succinylation of the Mitophagy-Related Protein VCP.

Regular quiescence and activation are important for the function of bone marrow mesenchymal stem cells (BMMSC), multipotent stem cells that are widely used in the clinic due to their capabilities in tissue repair and inflammatory disease treatment. TNF-α is previously reported to regulate BMMSC functions, including multilineage differentiation and immunoregulation. The present study demonstrates that TNF-α impedes quiescence and promotes the activation of BMMSC in vitro and in vivo. Mechanistically, the TNF-α-induced expression of KAT2A promotes the succinylation of VCP at K658, which inhibits the interaction between VCP and MFN1 and thus inhibits mitophagy. Furthermore, activated BMMSC exhibits stronger fracture repair and immunoregulation functions in vivo. This study contributes to a better understanding of the mechanisms of BMMSC quiescence and activation and to improving the effectiveness of BMMSC in clinical applications.

Drp1 regulated PINK1-dependent mitophagy protected duck follicular granulosa cells from acute heat stress injury

The mitochondrial quality control system is crucial in maintaining cellular homeostasis during environmental stress. Granulosa cells are the main cells secreting steroid hormones, and mitochondria are the key organelles for steroid hormone synthesis. The impact of the mitochondrial quality control system on granulosa cells' steroid hormone synthesis and survival under heat stress is still unclear. Here, we showed that acute heat stress induces mitochondrial damage and significantly increases the number of mitophagy-like vesicles in the cytoplasm of duck ovary granulosa cells at the ultra-structural level. Meanwhile, we also found heat stress significantly increased mitochondrial fission and mitophagy-related protein expression levels both in vivo and in vitro. Furthermore, by confocal fluorescence analysis, we discovered that LC3 was distributed spot-like manner near the nucleus in the heat treatment group, and the LC3 spots and lysosomes were colocalized with Mito-Tracker in the heat treatment group. We further detected the mitophagy-related protein in the cytoplasm and mitochondria, respectively. Results showed that the PINK1 protein was significantly increased both in cytoplasm and mitochondria, while the LC3-Ⅱ/LC3-Ⅰ ratio increase only occurred in mitochondrial. In addition, the autophagy protein induced by acute heat treatment was effectively inhibited by the mitophagy inhibitor CysA. Finally, we demonstrated that the alteration of cellular mitophagy by siRNA interference with Drp1 and PINK1 inhibited the steroid synthesis of granulosa cells and increased cell apoptosis. Study provides strong evidence that the Drp1 regulated PINK1-dependent mitophagy pathway protects follicular granulosa cells from acute heat stress-induced injury.

Liquid-liquid phase separation regulates alpha-synuclein aggregate and mitophagy in Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, and alpha-synuclein (α-syn) abnormal aggregate and mitochondrial dysfunction play a crucial role in its pathological development. Recent studies have revealed that proteins can form condensates through liquid-liquid phase separation (LLPS), and LLPS has been found to be widely present in α-syn aberrant aggregate and mitophagy-related protein physiological processes. This review summarizes the occurrence of α-syn LLPS and its influencing factors, introduces the production and transformation of the related protein LLPS during PINK1-Parkin-mediated mitophagy, hoping to provide new ideas and methods for the study of PD pathology.

Dietary apple polyphenols enhance mitochondrial turnover and respiratory chain enzymes.

Previous studies have demonstrated the beneficial effects of apple polyphenol (AP) intake on muscle endurance. Since mitochondria are critical for muscle endurance, we investigated mitochondrial enzyme activity, biogenesis, degradation and protein quality control. Twenty-four Wistar rats were randomly fed a 5% AP diet (5% AP group, n=8), a 0.5% AP diet (0.5% AP group, n=8), or a control diet (control group, n=8). After a 4-week feeding period, the expression level of peroxisome proliferator-activated receptor γ coactivator-1α, a mitochondrial biosynthetic factor, did not increase, whereas that of transcription factor EB, another regulator of mitochondrial synthesis, significantly increased. Moreover, the mitochondrial count did not differ significantly between the groups. In contrast, mitophagy-related protein levels were significantly increased. The enzymatic activities of mitochondrial respiratory chain complexes II, III and IV were significantly higher in the AP intake group than in the control group. We conclude that AP feeding increases the activity of respiratory chain complex enzymes in rat skeletal muscles. Moreover, mitochondrial biosynthesis and degradation may have increased in AP-treated rats. NEW FINDINGS: What is the central question of this study? Does the administration of apple polyphenols (AP) affect mitochondrial respiratory chain complex enzyme activity, biogenesis, degradation and protein quality control in rat skeletal muscles? What is the main finding and its importance? AP feeding increases respiratory chain complex enzyme activity in rat skeletal muscle. Moreover, AP administration increases transcription factor EB activation, and mitophagy may be enhanced to promote degradation of dysfunctional mitochondria, but mitochondrial protein quality control was not affected.

Fucoidan-proanthocyanidins nanoparticles protect against cisplatin-induced acute kidney injury by activating mitophagy and inhibiting mtDNA-cGAS/STING signaling pathway

Fucoidan (FU) is a natural polymer from marine organisms, which has been widely studied and applied in drug delivery. In this study, FU nanoparticles loaded with proanthocyanidins (PCs) (FU/PCs NPs) were prepared and their effect and mechanism in protecting cisplatin-induced acute kidney injury (AKI) were studied. The in vitro studies confirmed that FU/PCs NPs increased the antioxidant activity of free PCs and protected the death of human kidney proximal tubule (HK-2) cells induced by cisplatin. Further mechanism studies showed that FU/PCs NPs protected the mitochondrial damage induced by cisplatin, activated mitophagy, inhibited the release of mitochondrial DNA (mtDNA), and inhibited the cGAS/STING signal pathway. The in vivo results also indicated that FU/PCs NPs protected cisplatin-induced AKI, including inhibiting the increase of blood urea nitrogen (BUN) and serum creatinine (SCr) levels induced by cisplatin. The mechanism studies confirmed that cisplatin induced an increase in the expression of mitophagy-related protein Pink/Pakrin, mitochondrial mtDNA release and cGAS/STING expression in mice kidney tissues. Pre-administration of FU/PCs NPs further activated mitophagy, as well as inhibiting mtDNA release and cGAS/STING expression. In conclusion, our research proved the role of mitophagy-mtDNA-cGAS/STING signal was involved in cisplatin-induced AKI.

THE EMERGING ROLE OF IDH2-MEDIATED MITOPHAGY AND MTUPR IN ATHEROSCLEROSIS

Objective: Mitochondrial dysfunction is a risk factor for vascular disease by overexpressing ROS caused by some stimuli in mitochondria which causes oxidative stress and enhances vascular inflammatory response. Isocitrate dehydrogenase 2 (IDH2) is NADP+ dependent mitochondrial enzyme and an antioxidant enzyme that produces NADPH in the antioxidant system. Mitophagy and mitochondrial Unfolding Protein Response (mtUPR) are internal defense mechanism in mitochondria. In this study, we investigated whether IDH2 knockdown causes mitochondrial dysfunction then Mitophagy and mtUPR in vitro in HUVECs and in vivo in IDH2 knock out mice. Design and method: We examined expression of mitophagy and mtUPR-related gene in IDH2-deficient human umbilical vein endothelial cells (HUVECs) and its role in mitophagy and mtUPR in the endothelial cell and IDH2 KO animal tissues. Mitophagy and mtUPR were measured using the western blotting and qPCR. Results: We showed that knockdown of IDH2 expression induced depolarization of mitochondrial membrane potential (MMP). Mitochondrial dynamics is mitochondrial fusion and fission. Knockdown of IDH2 increased Drp1 (fission protein) and mfn1 (fusion protein) compared with Tom20 (control). IDH2 deficiency increase Mitophagy related protein PINK-1 and Parkin expression and mRNA level (PINK-1, Parkin, BNIP3, NIX, FUNDC-1). Moreover, knockdown of IDH2 induced mtUPR mRNA level (USP30, Clpp) in vitro. In addition, IDH2 deficiency increases mtUPR mRNA level and decreases PINK-1 and Parkin protein expression in vivo. Conclusions: Our data show that IDH2 deficiency induces mitochondrial dysfunction and then Mitophagy and mtUPR expression in endothelial cells. These findings provide novel strategy for the development of therapeutic agents for restoring mitochondrial and endothelial function.

Xuesaitong Combined with Dexmedetomidine Improves Cerebral Ischemia-Reperfusion Injury in Rats by Activating Keap1/Nrf2 Signaling and Mitophagy in Hippocampal Tissue.

Ischemic stroke is the most common type of cerebrovascular disease with high mortality and poor prognosis, and cerebral ischemia-reperfusion (CI/R) injury is the main murderer. Here, we attempted to explore the effects and mechanism of Xuesaitong (XST) combined with dexmedetomidine (Dex) on CI/R injury in rats. First, a rat model of CI/R injury was constructed via the middle cerebral artery occlusion (MCAO) method and treated with XST and Dex alone or in combination. Then, on the 5th and 10th days of treatment, the neurological impairment was assessed using the modified neurological severity scores (mNSS), the 8-arm radial maze test (8ARMT), novel object recognition test (NORT), and fear conditioning test (FCT). H&E staining was performed to observe the pathological changes of the hippocampus. ELISA and related kits were used to assess the monoamine neurotransmitters and antioxidant enzyme activities in the hippocampus. The ATP, mitochondrial membrane potential levels, and qRT-PCR of genes related to mitochondrial function were determined to assess mitochondrial functions in the hippocampus and western blot to determine Keap1/Nrf2 signaling pathway and mitophagy-related protein expression. The results showed that XST combined with Dex significantly reduced mNSS, improved spatial memory and learning deficits, and enhanced fear memory and cognitive memory ability in CI/R rats, which was superior to single-drug treatment. Moreover, XST combined with Dex treatment improved hippocampal histopathological damage; significantly increased the levels of monoamine neurotransmitters, neurotrophic factors, ATP, and mitochondrial membrane potential; and upregulated the activities of antioxidant enzymes and the expression of mitophagy-related proteins in the hippocampus of CI/R rats. XST combined with Dex treatment also activated the Keap1/Nrf2 signaling and upregulated the protein expression of downstream antioxidant enzymes HO-1 and NQ. Altogether, this study showed that a combination of XST and Dex could activate the Keap1/Nrf2 signaling and mitophagy to protect rats from CI/R-related neurological impairment.

Baicalin ameliorates CUMS-induced depression-like behaviors through activating AMPK/PGC-1α pathway and enhancing NIX-mediated mitophagy in mice

Mitochondrial dysfunction has been reported to be involved in the pathogenesis of depression, and mitophagy is a key pathway for mitochondrial quality control. This study aimed to investigate the effect of baicalin on mitophagy in the hippocampus of mice exposed to chronic unpredictable mild stress (CUMS) and explore its potential mechanism. After exposure to CUMS for 6 weeks, mice were given baicalin (20 mg/kg) or fluoxetine (20 mg/kg) by oral gavage for 4 weeks, and HT22 cells were injured by corticosterone (CORT) in vitro. Depression-like behaviors were assessed by sucrose preference test and tail suspension test. The mitochondrial structure was observed by transmission electron microscopy. Detection of mitophagy and mitophagy-related protein by mitophagy kit and Western blot. The results showed that baicalin improved depressive-like behaviors in CUMS mice, and ameliorated mitochondrial structural impairment in the hippocampus neuron. Baicalin significantly down-regulated light chain 3(LC3)II/I, protein sequestosome 1 (P62), and translocase of the outer membrane 20 (TOM20), and up-regulated Nip-like protein (NIX), Adenylate activated protein kinase (AMPK), and Peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1α. Furthermore, molecular docking showed that baicalin interacts with AMPK through hydrogen bonding. Baicalin increased NIX and AMPK, and improved mitophagy level and mitochondrial function in HT22 cells. Treatment with Phorbol 12-Myristate 13-acetate demonstrated that up-regulation of NIX ameliorated CORT-induced mitochondrial dysfunction in HT22 cells. In conclusion, the present study suggested that the antidepressant effect of baicalin may be related to the enhancement of NIX-mediated mitophagy through activating the AMPK/PGC-1α pathway by directly binding to AMPK.

Branched-chain amino acid supplementation suppresses the detraining-induced reduction of mitochondrial content in mouse skeletal muscle.

Exercise training enhances oxidative capacity whereas detraining reduces mitochondrial content in skeletal muscle. The strategy to suppress the detraining-induced reduction of mitochondrial content has not been fully elucidated. As previous studies reported that branched-chain amino acid (BCAA) ingestion increased mitochondrial content in skeletal muscle, we evaluated whether BCAA supplementation could suppress the detraining-induced reduction of mitochondrial content. Six-week-old male Institute of Cancer Research (ICR) mice were randomly divided into four groups as follows: control (Con), endurance training (Tr), detraining (DeTr), and detraining with BCAA supplementation (DeTr + BCAA). Mice in Tr, DeTr, and DeTr + BCAA performed treadmill running exercises [20-30 m/min, 60 min, 5 times/week, 4 weeks]. Then, mice in DeTr and DeTr + BCAA were administered with water or BCAA [0.6mg/g of body weight, twice daily] for 2 weeks of detraining. In whole skeletal muscle, mitochondrial enzyme activities and protein content were decreased after 2 weeks of detraining, but the reduction was suppressed by BCAA supplementation. Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) protein content, a master regulator of mitochondrial biogenesis, was decreased by detraining irrespective of BCAA ingestion. Regarding mitochondrial degradation, BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), a mitophagy-related protein, was significantly higher in the Tr group than in the DeTr + BCAA group, but not different from in the DeTr group. With respect to mitochondrial quality, BCAA ingestion did not affect oxygen consumption rate (OCR) and reactive oxygen species (ROS) production in isolated mitochondria. Our findings suggest that BCAA ingestion suppresses the detraining-induced reduction of mitochondrial content partly through inhibiting mitophagy.

Coenzyme Q10 ameliorates aging-induced memory deficits via modulation of apoptosis, oxidative stress, and mitophagy in aged rats.

The behavioral effects and molecular signaling mechanisms of Coenzyme Q10 (Q10) in age-related memory impairment are poorly understood. This study aimed to investigate the effects of Q10 on memory impairment, oxidative stress, apoptosis, and mitophagy in aged rats. 40 aged (24months old) and 10 young (3months old) male Wistar rats were randomly divided into the following groups (n=10/group): young + vehicle, aged + vehicle, and aged + Q10 (at 100, 200, 300mg/kg/day doses). Treatments were administrated orally by gavage for 2weeks. The novel object recognition test was used to assess episodic memory. Oxidative stress, apoptosis, and mitophagy-related protein expressions were measured in the hippocampus. We found that Q10 reversed aging-induced memory impairment at the dose of 300mg/kg. Moreover, aging was associated with a reduction in ATP production, decrease in mitophagy-related proteins (PINK, Parkin, and P62 levels and LC3II/I ratio), excessive generation of reactive oxygen species and lipid peroxidation, and apoptosis in the hippocampus, which were partially reversed following oral administration of Q10. These findings indicate the therapeutic potential of Q10 in aging-induced memory decline.