bims-tofagi 2023-10-15 papers

on Mitophagy

Issue of 2023‒10‒15
thirty-one papers selected by
Michele Frison, University of Cambridge and Aitor Martínez Zarate, Euskal Herriko Unibertsitatea

PINK1 and Parkin rescue motor defects and mitochondria dysfunction induced by a patient-derived HSPB3 mutant in Drosophila models.
PPTC7 maintains mitochondrial protein content by suppressing receptor-mediated mitophagy.
Neutrophil extracellular traps drive intestinal microvascular endothelial ferroptosis by impairing Fundc1-dependent mitophagy.
Ionizing radiation-induced mitophagy promotes ferroptosis by increasing intracellular free fatty acids.
Extracellular release in the quality control of the mammalian mitochondria.
Impaired mitophagosome-lysosome fusion mediates olanzapine-induced aging.
Low expression of PINK1 and PARK2 predicts poor prognosis in patients with esophageal squamous cell carcinoma.
Crosstalk between mitochondrial biogenesis and mitophagy to maintain mitochondrial homeostasis.
Targeting mitochondrial quality control for diabetic cardiomyopathy: Therapeutic potential of hypoglycemic drugs.
Parkin-Mediated Mitophagy by TGF-β Is Connected with Hepatic Stellate Cell Activation.
Corn peptides attenuate non-alcoholic fatty liver disease via PINK1/Parkin-mediated mitochondrial autophagy.
Sestrin2 protects against hypoxic nerve injury by regulating mitophagy through SESN2/AMPK pathway.
NL-1 Promotes PINK1-Parkin-Mediated Mitophagy Through MitoNEET Inhibition in Subarachnoid Hemorrhage.
Low-dose atorvastatin protects skeletal muscle mitochondria in high-fat diet-fed mice with mitochondrial autophagy inhibition and fusion enhancement.
Autophagy protects mitochondrial health in heart failure.
Dendrobium officinale polysaccharide decreases podocyte injury in diabetic nephropathy by regulating IRS-1/AKT signal and promoting mitophagy.
Fluorescent reporter of Caenorhabditis elegans Parkin: Regulators of its abundance and role in autophagy-lysosomal dynamics.
Shiga toxin 2 A-subunit induces mitochondrial damage, mitophagy and apoptosis via the interaction of Tom20 in Caco-2 cells.
Miquelianin in Folium Nelumbinis extract promotes white-to-beige fat conversion via blocking AMPK/DRP1/mitophagy and modulating gut microbiota in HFD-fed mice.
Ambra1 in exosomes secreted by HK-2 cells damaged by supersaturated oxalate induce mitophagy and autophagy-ferroptosis in normal HK-2 cells to participate in the occurrence of kidney stones.
Alcohol dehydrogenase 1 is a tubular mitophagy-dependent apoptosis inhibitor against septic acute kidney injury.
C-reactive protein accelerates DRP1-mediated mitochondrial fission by modulating ERK1/2-YAP signaling in cardiomyocytes.
Metformin modulates mitochondrial autophagy in renal tubular epithelial injury induced by high glucose via the Keap1/Nrf2 pathway.
Genetic and Functional Modifications Associated with Ovarian Cancer Cell Aggregation and Limited Culture Conditions.
Knockdown of NR3C1 inhibits the proliferation and migration of clear cell renal cell carcinoma through activating endoplasmic reticulum stress-mitophagy.
Activation of the Nrf-2 pathway by pinocembrin safeguards vertebral endplate chondrocytes against apoptosis and degeneration caused by oxidative stress.
The Pro-Oncogenic Protein IF1 Promotes Proliferation of Anoxic Cancer Cells during Re-Oxygenation.
Silencing USP19 alleviates cigarette smoke extract-induced mitochondrial dysfunction in BEAS-2B cells by targeting FUNDC1.
Inducing and monitoring mitochondrial pH changes with an iridium(III) complex via two-photon lifetime imaging.
FBXO7 Confers Mesenchymal Properties and Chemoresistance in Glioblastoma by Controlling Rbfox2-Mediated Alternative Splicing.
Molecular mechanisms involved in doxorubicin-induced cardiotoxicity: A bibliometrics analysis by VOSviewer.

Biochem Biophys Res Commun. 2023 Sep 29. pii: S0006-291X(23)01134-8. [Epub ahead of print]682 71-76

PINK1 and Parkin rescue motor defects and mitochondria dysfunction induced by a patient-derived HSPB3 mutant in Drosophila models.

Ji Eun Han, Kyong-Hwa Kang, Hyunjin Kim, Young Bin Hong, Byung-Ok Choi, Hyongjong Koh.

  Small heat shock proteins (sHSPs) are ATP-independent molecular chaperones with the α-crystalline domain that is critical to their chaperone activity. Within the sHSP family, three (HSPB1, HSPB3, and HSPB8) proteins are linked with inherited peripheral neuropathies, including distal hereditary motor neuropathy (dHMN) and Charco-Marie-Tooth disease (CMT). In this study, we introduced the HSPB3 Y118H (HSPB3Y118H) mutant gene identified from the CMT2 family in Drosophila. With a missense mutation on its α-crystalline domain, this human HSPB3 mutant gene induced a loss of motor activity accompanied by reduced mitochondrial membrane potential in fly neuronal tissues. Moreover, mitophagy, a critical mechanism of mitochondrial quality control, is downregulated in fly motor neurons expressing HSPB3Y118H. Surprisingly, PINK1 and Parkin, the core regulators of mitophagy, successfully rescued these motor and mitochondrial abnormalities in HSPB3 mutant flies. Results from the first animal model of HSPB3 mutations suggest that mitochondrial dysfunction plays a critical role in HSPB3-associated human pathology.

Keywords:  Charcot-Marie-Tooth disease; Distal hereditary motor neuropathies; Drosophila; HSPB3; PINK1; Parkin

DOI:  https://doi.org/10.1016/j.bbrc.2023.09.092
Nat Commun. 2023 Oct 13. 14(1): 6431

PPTC7 maintains mitochondrial protein content by suppressing receptor-mediated mitophagy.

Natalie M Niemi, Lia R Serrano, Laura K Muehlbauer, Catherine E Balnis, Lianjie Wei, Andrew J Smith, Keri-Lyn Kozul, Merima Forny, Olivia M Connor, Edrees H Rashan, Evgenia Shishkova, Kathryn L Schueler, Mark P Keller, Alan D Attie, Jonathan R Friedman, Julia K Pagan, Joshua J Coon, David J Pagliarini.

PPTC7 is a resident mitochondrial phosphatase essential for maintaining proper mitochondrial content and function. Newborn mice lacking Pptc7 exhibit aberrant mitochondrial protein phosphorylation, suffer from a range of metabolic defects, and fail to survive beyond one day after birth. Using an inducible knockout model, we reveal that loss of Pptc7 in adult mice causes marked reduction in mitochondrial mass and metabolic capacity with elevated hepatic triglyceride accumulation. Pptc7 knockout animals exhibit increased expression of the mitophagy receptors BNIP3 and NIX, and Pptc7-/- mouse embryonic fibroblasts (MEFs) display a major increase in mitophagy that is reversed upon deletion of these receptors. Our phosphoproteomics analyses reveal a common set of elevated phosphosites between perinatal tissues, adult liver, and MEFs, including multiple sites on BNIP3 and NIX, and our molecular studies demonstrate that PPTC7 can directly interact with and dephosphorylate these proteins. These data suggest that Pptc7 deletion causes mitochondrial dysfunction via dysregulation of several metabolic pathways and that PPTC7 may directly regulate mitophagy receptor function or stability. Overall, our work reveals a significant role for PPTC7 in the mitophagic response and furthers the growing notion that management of mitochondrial protein phosphorylation is essential for ensuring proper organelle content and function.

DOI: https://doi.org/10.1038/s41467-023-42069-w
Redox Biol. 2023 Oct 04. pii: S2213-2317(23)00307-5. [Epub ahead of print]67 102906

Neutrophil extracellular traps drive intestinal microvascular endothelial ferroptosis by impairing Fundc1-dependent mitophagy.

Chengnan Chu, Xinyu Wang, Chao Yang, Fang Chen, Lin Shi, Weiqi Xu, Kai Wang, Baochen Liu, Chenyang Wang, Dongping Sun, Weiwei Ding.

  Microvascular endothelial damage caused by intestinal ischemia‒reperfusion (II/R) is a primary catalyst for microcirculation dysfunction and enterogenous infection. Previous studies have mainly focused on how neutrophil extracellular traps (NETs) and ferroptosis cause intestinal epithelial injury, and little attention has been given to how NETs, mainly from circulatory neutrophils, affect intestinal endothelial cells during II/R. This study aimed to unravel the mechanisms through which NETs cause intestinal microvascular dysfunction. We first detected heightened local NET infiltration around the intestinal microvasculature, accompanied by increased endothelial cell ferroptosis, resulting in microcirculation dysfunction in both human and animal II/R models. However, the administration of the ferroptosis inhibitor ferrostatin-1 or the inhibition of NETs via neutrophil-specific peptidylarginine deiminase 4 (Pad4) deficiency led to positive outcomes, with reduced intestinal endothelial ferroptosis and microvascular function recovery. Moreover, RNA-seq analysis revealed a significant enrichment of mitophagy- and ferroptosis-related signaling pathways in HUVECs incubated with NETs. Mechanistically, elevated NET formation induced Fundc1 phosphorylation at Tyr18 in intestinal endothelial cells, which led to mitophagy inhibition, mitochondrial quality control imbalance, and excessive mitochondrial ROS generation and lipid peroxidation, resulting in endothelial ferroptosis and microvascular dysfunction. Nevertheless, using the mitophagy activator urolithin A or AAV-Fundc1 transfection could reverse this process and ameliorate microvascular damage. We first demonstrate that increased NETosis could result in intestinal microcirculatory dysfunction and conclude that suppressed NET formation can mitigate intestinal endothelial ferroptosis by improving Fundc1-dependent mitophagy. Targeting NETs could be a promising approach for treating II/R-induced intestinal microcirculatory dysfunction.

Keywords:  Ferroptosis; Fundc1-dependent mitophagy; Intestinal ischemia reperfusion; Microvascular dysfunction; Neutrophil extracellular traps

DOI:  https://doi.org/10.1016/j.redox.2023.102906
Cell Death Differ. 2023 Oct 12.

Ionizing radiation-induced mitophagy promotes ferroptosis by increasing intracellular free fatty acids.

Pengfei Yang, Jin Li, Tianyi Zhang, Yanxian Ren, Qiuning Zhang, Ruifeng Liu, Haining Li, Junrui Hua, Wen-An Wang, Jufang Wang, Heng Zhou.

Ferroptosis is a type of cell death characterized by the accumulation of intracellular iron and an increase in hazardous lipid peroxides. Ferroptosis and autophagy are closely related. Ionizing radiation is a frequently used cancer therapy to kill malignancies. We found that ionizing radiation induces both ferroptosis and autophagy and that there is a form of mutualism between the two processes. Ionizing radiation also causes lipid droplets to form in proximity to damaged mitochondria, which, through the action of mitophagy, results in the degradation of the peridroplet mitochondria by lysosomes and the consequent release of free fatty acids and a significant increase in lipid peroxidation, thus promoting ferroptosis. Ionizing radiation has a stronger, fatal effect on cells with a high level of mitophagy, and this observation suggests a novel strategy for tumor treatment.

DOI: https://doi.org/10.1038/s41418-023-01230-0
J Biomed Sci. 2023 Oct 08. 30(1): 85

Extracellular release in the quality control of the mammalian mitochondria.

Kuei-Hsiang Pan, Hung Chang, Wei Yuan Yang.

  Mammalian cells release a wealth of materials to their surroundings. Emerging data suggest these materials can even be mitochondria with perturbed morphology and aberrant function. These dysfunctional mitochondria are removed by migrating cells through membrane shedding. Neuronal cells, cardiomyocytes, and adipocytes send dysfunctional mitochondria into the extracellular space for nearby cells to degrade. Various studies also indicate that there is an interplay between intracellular mitochondrial degradation pathways and mitochondrial release in handling dysfunctional mitochondria. These observations, in aggregate, suggest that extracellular release plays a role in quality-controlling mammalian mitochondria. Future studies will help delineate the various types of molecular machinery mammalian cells use to release dysfunctional mitochondria. Through the studies, we will better understand how mammalian cells choose between intracellular degradation and extracellular release for the quality control of mitochondria.

Keywords:  Autophagy; Extracellular vesicles; Mitochondria; Mitophagy; Organelle quality control

DOI:  https://doi.org/10.1186/s12929-023-00979-3
Aging Cell. 2023 Oct 13. e14003

Impaired mitophagosome-lysosome fusion mediates olanzapine-induced aging.

Xi Chen, Zhizhen Wang, Peng Zheng, Anjila Dongol, Yuanyi Xie, Xing Ge, Mingxuan Zheng, Xuemei Dang, Zehra Boz Seyhan, Nathan Nagaratnam, Yinghua Yu, Xu-Feng Huang.

  The lifespan of schizophrenia patients is significantly shorter than the general population. Olanzapine is one of the most commonly used antipsychotic drugs (APDs) for treating patients with psychosis, including schizophrenia and bipolar disorder. Despite their effectiveness in treating positive and negative symptoms, prolonged exposure to APDs may lead to accelerated aging and cognitive decline, among other side effects. Here we report that dysfunctional mitophagy is a fundamental mechanism underlying accelerated aging induced by olanzapine, using in vitro and in vivo (Caenorhabditis elegans) models. We showed that the aberrant mitophagy caused by olanzapine was via blocking mitophagosome-lysosome fusion. Furthermore, olanzapine can induce mitochondrial damage and hyperfragmentation of the mitochondrial network. The mitophagosome-lysosome fusion in olanzapine-induced aging models can be restored by a mitophagy inducer, urolithin A, which alleviates defective mitophagy, mitochondrial damage, and fragmentation of the mitochondrial network. Moreover, the mitophagy inducer ameliorated behavioral changes induced by olanzapine, including shortened lifespan, and impaired health span, learning, and memory. These data indicate that olanzapine impairs mitophagy, leading to the shortened lifespan, impaired health span, and cognitive deficits. Furthermore, this study suggests the potential application of mitophagy inducers as therapeutic strategies to reverse APD-induced adverse effects associated with accelerated aging.

Keywords:  accelerated aging; antipsychotics; cognition; health span; lifespan; mitophagy; mitophagy inducer; olanzapine

DOI:  https://doi.org/10.1111/acel.14003
World J Surg Oncol. 2023 Oct 13. 21(1): 321

Low expression of PINK1 and PARK2 predicts poor prognosis in patients with esophageal squamous cell carcinoma.

Xiangyun Lu, Yongkun Yao, Yandi Ma, Xudong Zhang, Hao Peng, Yuhui Pei, Yulin Lu, Lianghai Wang.

  BACKGROUND: The Parkinson's disease (PD) gene family expression is strongly linked to tumor development and progression; PINK1 and PARK2 are essential members of the PD gene family. However, the relationship between PINK1 and PARK2 and esophageal squamous cell carcinoma (ESCC) remains unknown. This research aims to clarify the prognostic value of PINK1 and PARK2 in ESCC.METHODS: PINK1 and PARK2 protein levels in 232 ESCC specimens, and 125 matched adjacent normal tissues were detected by immunohistochemistry. The relationship between PINK1 and PARK2 protein expression and clinicopathological features were analyzed. Kaplan-Meier survival analysis was performed to estimate the prognostic value of the PINK1 and PARK2 proteins in patients. Cox univariate and multivariate analyses were used to assess the risk factors affecting the OS for patients with ESCC.
RESULTS: PINK1 and PARK2 had low expression in ESCC. Patients with low PINK1 had worse differentiation and advanced T and TNM stages. Lower PARK2 expression was linked to lymph node metastases and an advanced TNM stage. Furthermore, reduced PINK1 and PARK2 levels were associated with a poor prognosis for ESCC. Cox univariate and multivariate analyses revealed that PINK1, PARK2, and tumor size were closely associated with the prognosis of patients with ESCC, and PARK2 was an independent risk factor for patients with ESCC. Finally, the PINK1 and PARK2 proteins were closely related and shared the same signal pathway.
CONCLUSIONS: PINK1 and PARK2 could work as tumor suppressors in ESCC and are likely to become new treatment targets for ESCC.

Keywords:  Esophageal squamous cell carcinoma; PARK2; PINK1; Prognosis

DOI:  https://doi.org/10.1186/s12957-023-03206-3
J Biomed Sci. 2023 Oct 12. 30(1): 86

Crosstalk between mitochondrial biogenesis and mitophagy to maintain mitochondrial homeostasis.

Lei Liu, Yanjun Li, Guo Chen, Quan Chen.

  Mitochondrial mass and quality are tightly regulated by two essential and opposing mechanisms, mitochondrial biogenesis (mitobiogenesis) and mitophagy, in response to cellular energy needs and other cellular and environmental cues. Great strides have been made to uncover key regulators of these complex processes. Emerging evidence has shown that there exists a tight coordination between mitophagy and mitobiogenesis, and their defects may cause many human diseases. In this review, we will first summarize the recent advances made in the discovery of molecular regulations of mitobiogenesis and mitophagy and then focus on the mechanism and signaling pathways involved in the simultaneous regulation of mitobiogenesis and mitophagy in the response of tissue or cultured cells to energy needs, stress, or pathophysiological conditions. Further studies of the crosstalk of these two opposing processes at the molecular level will provide a better understanding of how the cell maintains optimal cellular fitness and function under physiological and pathophysiological conditions, which holds promise for fighting aging and aging-related diseases.

Keywords:  Aging; Aging-related diseases; Mitochondrial biogenesis; Mitochondrial quality; Mitophagy; Mitophagy receptors

DOI:  https://doi.org/10.1186/s12929-023-00975-7
Biomed Pharmacother. 2023 Oct 09. pii: S0753-3322(23)01467-1. [Epub ahead of print]168 115669

Targeting mitochondrial quality control for diabetic cardiomyopathy: Therapeutic potential of hypoglycemic drugs.

Yutong Zhou, Wendong Suo, Xinai Zhang, Jiaojiao Liang, Weizhe Zhao, Yue Wang, Hong Li, Qing Ni.

  Diabetic cardiomyopathy is a chronic cardiovascular complication caused by diabetes that is characterized by changes in myocardial structure and function, ultimately leading to heart failure and even death. Mitochondria serve as the provider of energy to cardiomyocytes, and mitochondrial dysfunction plays a central role in the development of diabetic cardiomyopathy. In response to a series of pathological changes caused by mitochondrial dysfunction, the mitochondrial quality control system is activated. The mitochondrial quality control system (including mitochondrial biogenesis, fusion and fission, and mitophagy) is core to maintaining the normal structure of mitochondria and performing their normal physiological functions. However, mitochondrial quality control is abnormal in diabetic cardiomyopathy, resulting in insufficient mitochondrial fusion and excessive fission within the cardiomyocyte, and fragmented mitochondria are not phagocytosed in a timely manner, accumulating within the cardiomyocyte resulting in cardiomyocyte injury. Currently, there is no specific therapy or prevention for diabetic cardiomyopathy, and glycemic control remains the mainstay. In this review, we first elucidate the pathogenesis of diabetic cardiomyopathy and explore the link between pathological mitochondrial quality control and the development of diabetic cardiomyopathy. Then, we summarize how clinically used hypoglycemic agents (including sodium-glucose cotransport protein 2 inhibitions, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, thiazolidinediones, metformin, and α-glucosidase inhibitors) exert cardioprotective effects to treat and prevent diabetic cardiomyopathy by targeting the mitochondrial quality control system. In addition, the mechanisms of complementary alternative therapies, such as active ingredients of traditional Chinese medicine, exercise, and lifestyle, targeting mitochondrial quality control for the treatment of diabetic cardiomyopathy are also added, which lays the foundation for the excavation of new diabetic cardioprotective drugs.

Keywords:  DPP4i; Diabetic cardiomyopathy; GLP1-RA; Mitochondrial quality control; SGLT2i

DOI:  https://doi.org/10.1016/j.biopha.2023.115669
Int J Mol Sci. 2023 Oct 02. pii: 14826. [Epub ahead of print]24(19):

Parkin-Mediated Mitophagy by TGF-β Is Connected with Hepatic Stellate Cell Activation.

Ji Hyun Lee, Kyu Min Kim, Eun Hee Jung, Hye Rim Lee, Ji Hye Yang, Sam Seok Cho, Sung Hwan Ki.

  Hepatic stellate cells (HSCs) are the main contributors to the development and progression of liver fibrosis. Parkin is an E3 ligase involved in mitophagy mediated by lysosomes that maintains mitochondrial homeostasis. Unfortunately, there is little information regarding the regulation of parkin by transforming growth factor-β (TGF-β) and its association with HSC trans-differentiation. This study showed that parkin is upregulated in fibrotic conditions and elucidated the underlying mechanism. Parkin was observed in the cirrhotic region of the patient liver tissues and visualized using immunostaining and immunoblotting of mouse fibrotic liver samples and primary HSCs. The role of parkin-mediated mitophagy in hepatic fibrogenesis was examined using TGF-β-treated LX-2 cells with mitophagy inhibitor, mitochondrial division inhibitor 1. Parkin overexpression and its colocalization with desmin in human tissues were found. Increased parkin in fibrotic liver homogenates of mice was observed. Parkin was expressed more abundantly in HSCs than in hepatocytes and was upregulated under TGF-β. TGF-β-induced parkin was due to Smad3. TGF-β facilitated mitochondrial translocation, leading to mitophagy activation, reversed by mitophagy inhibitor. However, TGF-β did not change mitochondrial function. Mitophagy inhibitor suppressed profibrotic genes and HSC migration mediated by TGF-β. Collectively, parkin-involved mitophagy by TGF-β facilitates HSC activation, suggesting mitophagy may utilize targets for liver fibrosis.

Keywords:  Smad2; hepatic stellate cell; liver fibrosis; mitophagy; parkin

DOI:  https://doi.org/10.3390/ijms241914826
Food Nutr Res. 2023 ;67

Corn peptides attenuate non-alcoholic fatty liver disease via PINK1/Parkin-mediated mitochondrial autophagy.

Zhicui Yao, Xiaoling Li, Wentao Wang, Peng Ren, Shiming Song, Haiyue Wang, Ying Xie, Xingbo Li, Zengning Li.

  Background: Corn peptides, a novel food prepared from corn gluten meal (CGM) by enzymatic hydrolysis or microbial fermentation, have attracted considerable interest owing to their various bioactive properties. However, the underlying mechanism of corn peptides attenuate non-alcoholic fatty liver disease (NAFLD) remains unclear.Objective: This study aimed to investigate the effect of corn peptides in NAFLD and to decipher the underlying mechanisms.
Design: NAFLD was induced by a high-fat diet (HFD) for 10 weeks. Corn peptides were administered during the period. Human hepatocellular carcinomas (HepG2) cells induced by free fatty acids were used for this mechanism study.
Results: Corn peptides alleviated HFD-induced histopathological changes, disorders of lipid metabolism, and mitochondrial damage. Moreover, corn peptides blocked mitophagy suppression by HFD based on the increased LC3, ATG7 expressions, as well as decreased P62 levels. Corn peptides increased the expression of proteins involved in fatty acid β-oxidation, such as PPARα and PGC-1α. Corn peptides also improved the Ser/Thr kinase PINK1 (PINK1) and the E3 ubiquitin ligase Parkin (Parkin) translocation to mitochondria, which is confirmed by immunofluorescence. Furthermore, stable knockdown of PINK1 by PINK1 SiRNA in HepG2 inhibited PINK1-Parkin-associated mitophagy and resulted in lipid accumulation.
Conclusion: Corn peptides improved cell injury and ameliorated mitochondrial dysfunction and lipid accumulation via PINK1/Parkin-mediated autophagy in NAFLD. Thus, corn peptides could be a promising nutritional molecule with natural functions for preventing NAFLD.

Keywords:  PINK1/Parkin pathway; corn peptides; mitochondrial autophagy; non-alcoholic fatty liver disease

DOI:  https://doi.org/10.29219/fnr.v67.9547
Front Mol Biosci. 2023 ;10 1266243

Sestrin2 protects against hypoxic nerve injury by regulating mitophagy through SESN2/AMPK pathway.

Cunyao Pan, Chongyi Ai, Lanlan Liang, Baoyi Zhang, Qionglin Li, Lingling Pu, Zirou Wang, Weili Liu, Zhaoli Chen, Hui Liu, Xinxing Wang.

  Hypoxia induced by high altitude can lead to severe neurological dysfunction. Mitophagy is known to play a crucial role in hypoxic nerve injury. However, the regulatory mechanism of mitophagy during this injury remains unclear. Recent studies have highlighted the role of Sestrin2 (SESN2), an evolutionarily conserved stress-inducible protein against acute hypoxia. Our study demonstrated that hypoxia treatment increased SESN2 expression and activated mitophagy in PC12 cells. Furthermore, the knock-out of Sesn2 gene led to a significant increase in mitochondrial membrane potential and ATP concentrations, which protected the PC12 cells from hypoxic injury. Although the AMPK/mTOR pathway was significantly altered under hypoxia, it does not seem to participate in mitophagy regulation. Instead, our data suggest that the mitophagy receptor FUNDC1 plays a vital role in hypoxia-induced mitophagy. Moreover, SESN2 may function through synergistic regulation with other pathways, such as SESN2/AMPK, to mediate cellular adaptation to hypoxia, including the regulation of mitophagy in neuron cells. Therefore, SESN2 plays a critical role in regulating neural cell response to hypoxia. These findings offer valuable insights into the underlying molecular mechanisms governing the regulation of mitophagy under hypoxia and further highlight the potential of SESN2 as a promising therapeutic target for hypoxic nerve injury.

Keywords:  AMPK; FUNDC1; SESN2; hypoxia; mitophagy; neurological dysfunction

DOI:  https://doi.org/10.3389/fmolb.2023.1266243
Neurochem Res. 2023 Oct 12.

NL-1 Promotes PINK1-Parkin-Mediated Mitophagy Through MitoNEET Inhibition in Subarachnoid Hemorrhage.

Tongyu Zhang, Minghai Zhang.

  NL-1 is a mitoNEET ligand known for its antileukemic effects and has recently shown neuroprotective effects in an ischemic stroke model. However, its underlying process in subarachnoid hemorrhage (SAH) is still unclear. Thus, we aimed to investigate the possible mechanism of NL-1 after SAH in rats. 112 male adult Sprague-Dawley rats were used for experiments. SAH model was performed with endovascular perforation. Rats were dosed intraperitoneally (i.p.) with NL-1 (3 mg/kg, 10 mg/kg, 30 mg/kg) or a vehicle (10% DMSO aqueous solution) at 1 h after SAH. A novel mitophagy inhibitor liensinine (60 mg/kg) was injected i.p. 24 h before SAH. SAH grades, short-term and long-term neurological scores were measured for neurobehavior. TdTmediated dUTP nick end labeling (TUNEL) staining, dihydroethidium (DHE) staining and western blot measurements were used to detect the outcomes and mechanisms of NL-1 administration. NL-1 treatment significantly improved short-term neurological behavior in Modified Garcia and beam balance sores in comparison with SAH + vehicle group. NL-1 administration also increased mitoNEET which induced phosphatase and tensin-induced kinase 1 (PINK1), Parkin and LC3II related mitophagy compared with SAH + vehicle group. In addition, the expressions of apoptotic protein Cleaved Caspase-3 and oxidative stress related protein Romo1 in NL-1 treatment group were reversed from SAH + vehicle group. Meanwhile, NL-1 treatment notably reduced TUNEL-positive cells, DHE-positive cells compared with SAH + vehicle group. NL-1 treatment notably improved long-term neurological behavior in rotarod and water maze tests compared to SAH + vehicle group. However, the administration of liensinine may inhibit the treatment effect of NL-1, leading to reduced expression of mitophagy markers Pink1, Parkin, LC3I/II, and increased expressions of Romo1 and Cleaved Caspase-3. NL-1 induced PINK1/PARKIN related mitophagy via mitoNEET, which reduced oxidative stress and apoptosis in early brain injury after SAH in rats. NL-1 may serve as a prospective drug for the treatment of SAH.

Keywords:  Apoptosis; MitoNEET; Mitophagy; NL-1; Oxidative stress; Subarachnoid hemorrhage

DOI:  https://doi.org/10.1007/s11064-023-04024-5
Eur J Pharmacol. 2023 Oct 06. pii: S0014-2999(23)00597-6. [Epub ahead of print] 176085

Low-dose atorvastatin protects skeletal muscle mitochondria in high-fat diet-fed mice with mitochondrial autophagy inhibition and fusion enhancement.

Peng Zheng, Qian Zhang, Wenjing Ma, Ran Hu, Yilu Gu, Zhiping Bian, Di Yang, Xiangjian Chen, Hengfang Wu.

  Despite the great clinical benefits of statins in cardiovascular diseases, their widespread use may lead to adverse muscle reactions associated with mitochondrial dysfunction. Some studies have demonstrated that statins provide substantial improvement to skeletal muscle health in mice. Our previous study found that oral treatment with atorvastatin (Ator, 3 mg/kg) protected myocardial mitochondria in high-fat diet (HFD)-fed mice. Therefore, this study aimed to explore the influence of low-dose Ator (3 mg/kg) on mitochondria in skeletal muscle under cholesterol overload. Male C57BL/6J mice were fed a HFD for 18 weeks and orally administered Ator (3 mg/kg) during the last 12 weeks. Ator treatment had no effects on elevated serum cholesterol and glucose levels in HFD-fed mice. Serum creatine kinase levels and the cross-sectional area of muscle cells were not affected by HFD feeding or Ator treatment. Increased expression of PINK1-LC3 II (activated mitophagy), MFN2 (fusion), and PGC-1α (biogenesis) proteins was induced in the skeletal muscles of HFD-fed mice. Treatment with Ator inhibited PINK1 and LC3 II protein expression, but further promoted MFN1, MFN2, and OPA1 expression. The impairments in mitochondrial quality and morphology in HFD-fed mice was attenuated by treatment with Ator. Furthermore, Ator treatment enhanced glucose oxidation capacity and restored ATP production in the skeletal muscles of HFD-fed mice. The study reveals that low-dose Ator has a protective effect on muscle mitochondria in mice, likely through inhibiting mitophagy and enhancing mitochondrial fusion. This suggests that skeletal muscle mitochondria may be one of low-dose Ator-mediated protective targets.

Keywords:  Atorvastatin; High cholesterol; High-fat diet; Mitochondria; Mitochondrial quality-control network; Skeletal muscle

DOI:  https://doi.org/10.1016/j.ejphar.2023.176085
Heart Fail Rev. 2023 Oct 12.

Autophagy protects mitochondrial health in heart failure.

Yating Tang, Wenlong Xu, Yu Liu, Jiajun Zhou, Kai Cui, Yanmei Chen.

  The progression of heart failure is reported to be strongly associated with homeostatic imbalance, such as mitochondrial dysfunction and abnormal autophagy, in the cardiomyocytes. Mitochondrial dysfunction triggers autophagic and cardiac dysfunction. In turn, abnormal autophagy impairs mitochondrial function and leads to apoptosis or autophagic cell death under certain circumstances. These events often occur concomitantly, forming a vicious cycle that exacerbates heart failure. However, the role of the crosstalk between mitochondrial dysfunction and abnormal autophagy in the development of heart failure remains obscure and the underlying mechanisms are mainly elusive. The potential role of the link between mitochondrial dysfunction and abnormal autophagy in heart failure progression has recently garnered attention. This review summarized recent advances of the interactions between mitochondria and autophagy during the development of heart failure.

Keywords:  Autophagy; Heart failure; Mitochondria health; Mitochondria-targeted therapeutics; Mitochondrial quality control

DOI:  https://doi.org/10.1007/s10741-023-10354-x
Aging (Albany NY). 2023 Oct 08. 15

Dendrobium officinale polysaccharide decreases podocyte injury in diabetic nephropathy by regulating IRS-1/AKT signal and promoting mitophagy.

Huahua Li, Jin Zheng, Yacen Wu, Hong Zhou, Suli Zeng, Quanqing Li.

  BACKGROUNDS: High glucose (HG) caused oxidative stress and mitochondrial dysfunction, resulting in insulin resistance in podocytes, a key mechanism of diabetic nephropathy. Dendrobium officinale polysaccharide (DOP) was able to improve insulin resistance and antioxidant capability.OBJECTIVE: The purpose of this study is to explore the mechanism by which DOP decreases the podocyte injury induced by HG.
METHODS: MPC5 cells were treated with HG, DOP, and IRS-1/2 inhibitor NT157. Afterwards, glucose consumption, generations of ROS and MDA were measured using the detection kits. Mitophagy was monitored using both MtphagTracyker and LysoTracker. The mitochondrial membrane potential was evaluated by JC-1 staining. DOP was also used in a mouse model of diabetes, with the measurements of urine albumin, blood creatinine and blood urea nitrogen.
RESULTS: Treatment with DOP suppressed the HG-induced reduction of glucose consumption, the phosphorylation of IRS-1 (phospho Y632), AKT (phospho Ser473 and Thr308) and Nephrin. In addition, HG-induced augment of ROS and MDA, formation of γ-H2A.X foci and translocation of AKT to nucleus were inhibited by DOP. DOP enhanced mitophagy, which was associated with decreased mitochondrial membrane potential and ROS production. DOP conferred protective effect on podocyte in the diabetic mouse by reducing the albumin/creatinine ratio and blood urea nitrogen, and restoring Nephrin expression in podocytes.
CONCLUSIONS: DOP alleviates HG-induced podocyte injuryby regulating IRS-1/AKT signal and promoting mitophagy.

Keywords:  dendrobium officinale polysaccharide; diabetic nephropathy; mitophagy; oxidative stress; podocyte

DOI:  https://doi.org/10.18632/aging.205075
Open Res Eur. 2022 ;2 23

Fluorescent reporter of Caenorhabditis elegans Parkin: Regulators of its abundance and role in autophagy-lysosomal dynamics.

Roman Vozdek, Bingying Wang, Kathy H Li, Peter P Pramstaller, Andrew A Hicks, Dengke K Ma.

  Background: Parkin, which when mutated leads to early-onset Parkinson's disease, acts as an E3 ubiquitin ligase. How Parkin is regulated for selective protein and organelle targeting is not well understood. Here, we used protein interactor and genetic screens in Caenorhabditis elegans ( C. elegans) to identify new regulators of Parkin abundance and showed their impact on autophagy-lysosomal dynamics and alpha-Synuclein processing. Methods: We generated a transgene encoding mCherry-tagged C. elegans Parkin - Parkinson's Disease Related 1 (PDR-1). We performed protein interactor screen using Co-immunoprecipitation followed by mass spectrometry analysis to identify putative interacting partners of PDR-1. Ribonucleic acid interference (RNAi) screen and an unbiased mutagenesis screen were used to identify genes regulating PDR-1 abundance. Confocal microscopy was used for the identification of the subcellular localization of PDR-1 and alpha-Synuclein processing. Results: We show that the mCherry::pdr-1 transgene rescues the mitochondrial phenotype of pdr-1 mutants and that the expressed PDR-1 reporter is localized in the cytosol with enriched compartmentalization in the autophagy-lysosomal system. We determined that the transgenic overexpression of the PDR-1 reporter, due to inactivated small interfering RNA (siRNA) generation pathway, disrupts autophagy-lysosomal dynamics. From the RNAi screen of putative PDR-1 interactors we found that the inactivated Adenine Nucleotide Translocator ant-1.1/hANT, or hybrid ubiquitin genes ubq-2/h UBA52 and ubl-1/h RPS27A encoding a single copy of ubiquitin fused to the ribosomal proteins L40 and S27a, respectively, induced PDR-1 abundance and affected lysosomal dynamics. In addition, we demonstrate that the abundant PDR-1 plays a role in alpha-Synuclein processing. Conclusions: These data show that the abundant reporter of C. elegans Parkin affects the autophagy-lysosomal system together with alpha-Synuclein processing which can help in understanding the pathology in Parkin-related diseases.

Keywords:  C. elegans; Parkin; Parkinson’s disease; RNA interference; Synuclein; autophagy; genetic screen

DOI:  https://doi.org/10.12688/openreseurope.14235.2
Heliyon. 2023 Sep;9(9): e20012

Shiga toxin 2 A-subunit induces mitochondrial damage, mitophagy and apoptosis via the interaction of Tom20 in Caco-2 cells.

Jie Tang, Xiaoxue Lu, Tao Zhang, Yuyang Feng, Qiaolin Xu, Jing Li, Yuanzhi Lan, Huaxing Luo, Linghai Zeng, Yuanyuan Xiang, Yan Zhang, Qian Li, Xuhu Mao, Bin Tang, Dongzhu Zeng.

  Shiga toxin type 2 (Stx2) is the primary virulence factor produced by Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC), which causes epidemic outbreaks of gastrointestinal sickness and potentially fatal sequela hemolytic uremic syndrome (HUS). Most studies on Stx2-induced apoptosis have been performed with holotoxins, but the mechanism of how the A and B subunits of Stx2 cause apoptosis in cells is not clear. Here, we found that Stx2 A-subunit (Stx2A) induced mitochondrial damage, PINK1/Parkin-dependent mitophagy and apoptosis in Caco-2 cells. PINK1/Parkin-dependent mitophagy caused by Stx2A reduced apoptosis by decreasing the accumulation of reactive oxidative species (ROS). Mechanistically, Stx2A interacts with Tom20 on mitochondria to initiate the translocation of Bax to mitochondria, leading to mitochondrial damage and apoptosis. Overall, these data suggested that Stx2A induces mitochondrial damage, mitophagy and apoptosis via the interaction of Tom20 in Caco-2 cells and that mitophagy caused by Stx2A ameliorates apoptosis by eliminating damaged mitochondria. These findings provide evidence for the potential use of Tom20 inhibition as an anti-Shiga toxin therapy.

Keywords:  Apoptosis; Mitophagy; Shiga toxin; Shiga toxin type 2; Tom20

DOI:  https://doi.org/10.1016/j.heliyon.2023.e20012
Food Chem Toxicol. 2023 Oct 05. pii: S0278-6915(23)00491-X. [Epub ahead of print]181 114089

Miquelianin in Folium Nelumbinis extract promotes white-to-beige fat conversion via blocking AMPK/DRP1/mitophagy and modulating gut microbiota in HFD-fed mice.

Zhenyu Wang, Tian Yang, Maomao Zeng, Zhaojun Wang, Qiuming Chen, Jie Chen, Mark Christian, Zhiyong He.

  The main purpose of the present study was to investigate the effect of miquelianin (quercetin 3-O-glucuronide, Q3G), one of the main flavonoids in the Folium Nelumbinis extract (FNE), on beige adipocyte formation and its underlying mechanisms. In 3T3-L1 adipocytes Q3G (12.8%)-rich FNE treatment upregulated beige-related markers such as SIRT1, COX2, PGC-1α, TFAM, and UCP1. Furthermore, Q3G enhanced mitochondrial biosynthesis and inhibited mitophagy by downregulating the expression of PINK1, PARKIN, BECLIN1 and LC-3B in 3T3-L1 cells. Moreover, in high-fat-diet (HFD)-fed mice, Q3G markedly inhibited body weight gain, reduced blood glucose/lipid levels, reduced white adipose tissues (WAT) and mitigated hepatic steatosis. Meanwhile, the induced beiging accompanied by suppressed mitophagy was also demonstrated in inguinal WAT (iWAT). Chemical intervention of AMPK activity with Compound C (Com C) and Acadesine (AICAR) revealed that AMPK/DRP1 signaling was involved in Q3G-mediated mitophagy and the beiging process. Importantly, 16S rRNA sequencing analysis showed that Q3G beneficially reshaped gut microbiota structure, specifically inhibiting unclassified_Lachnospiraceae, Faecalibaculum, Roseburia and Colidextribacter while increasing Bacteroides, Akkermansia and Mucispirillum, which may potentially facilitate WAT beiging. Collectively, our findings provide a novel biological function for Folium Nelumbinis and Q3G in the fight against obesity through activating the energy-dissipating capacity of beige fat.

Keywords:  Beige fat; Folium nelumbinis; Gut microbiota; Miquelianin; Mitophagy

DOI:  https://doi.org/10.1016/j.fct.2023.114089
Biochim Biophys Acta Mol Cell Res. 2023 Oct 06. pii: S0167-4889(23)00177-5. [Epub ahead of print]1871(1): 119604

Ambra1 in exosomes secreted by HK-2 cells damaged by supersaturated oxalate induce mitophagy and autophagy-ferroptosis in normal HK-2 cells to participate in the occurrence of kidney stones.

Xiaozhe Su, Chao Song, Ziqi He, Qianlin Song, Lingchao Meng, Caitao Dong, Jiawei Zhou, Hu Ke, Yunhe Xiong, Junwei Liu, Wenbiao Liao, Sixing Yang.

  Injury to the renal tubular epithelium has emerged as a leading factor underlying the formation of kidney stones. Indeed, epithelial cell damage contributes to the adherence and aggregation of crystals, thereby accelerating the formation of renal stones. Meanwhile, exosomes play an instrumental role in cellular communication, including DNA, RNA, mRNA, etc. In this study, homogenous cells were treated with exosomes derived from damaged cells in an attempt to establish "positive feedback" of cell damage, and the desired results were achieved. To begin, a serum-free medium and supersaturated concentrations of oxalate were added to the HK-2 cell line, and then exosomes were isolated from the two groups for analysis and comparison, and the autophagy-related gene Ambra1 (autophagy and beclin-1 regulator 1) was detected. Subsequently, normal HK-2 cells were treated with exosomes, and the related indexes of autophagy, ferroptosis and mitophagy were determined. Thereafter, Ambra1 was knocked down in exosome-derived HK-2 cells, resulting in the down-regulation of Ambra1 expression in exosomes produced by HK-2 cells following oxalate intervention. Thereafter, the ability of exosomes to stimulate autophagy, mitophagy and ferroptosis was re-evaluated in HK-2 cells after Ambra1 knockdown. The results corroborated that exosomes secreted by oxalate-treated HK-2 can directly elevate autophagy, ferroptosis and mitophagy levels in normal cells, and this effect was significantly mitigated following Ambra1 knockdown within exosomes. Meanwhile, exosomes-induced autophagy and ferroptosis were alleviated after knockdown of beclin-1 in recipient HK-2 cells. These results further suggest that beclin-1 plays a critical role in the process of exosome-induced autophagy-ferroptosis.

Keywords:  Ambra1; Autophagy; Exosome; Ferroptosis; Kidney stone; Mitophagy

DOI:  https://doi.org/10.1016/j.bbamcr.2023.119604
Exp Cell Res. 2023 Oct 06. pii: S0014-4827(23)00352-X. [Epub ahead of print] 113804

Alcohol dehydrogenase 1 is a tubular mitophagy-dependent apoptosis inhibitor against septic acute kidney injury.

Yang Zheng, Juan-Juan Cai, Xue Yang, Zi-Qiang Shao, Jing-Quan Liu, Xiang-Hong Yang, Ren-Hua Sun, Bang-Chuan Hu, Shi-Jing Mo, Lan-Juan Li.

  Alcohol dehydrogenase 1 (ADH1) is an alcohol-oxidizing enzyme with poorlydefined biology. Here we report that ADH1 is highly expressed in kidneys of mice with lethal endotoxemia and is transcriptionally upregulated in tubular cells by lipopolysaccharide (LPS) stimuli through TLR4/NF-κB cascade. The Adh1 knockout (Adh1KO) mice with lethal endotoxemia displayed increased susceptibility to acute kidney injury (AKI) but not systemic inflammatory response. Adh1KO mice develop more severe tubular cell apoptosis in comparison to Adh1 wild-type (Adh1WT) mice during course of lethal endotoxemia. ADH1 deficiency facilitates the LPS-induced tubular cell apoptosis in a caspase-dependent manner. Mechanistically, ADH1 deficiency dampens tubular mitophagy that relies on PINK1-Parkin pathway characterized by the reduced membrane potential, reactive oxygen species (ROS) and release of fragmented mtDNA to cytosol. Kidney-specific overexpression of PINK1 and Parkin by adeno-associated viral vector 9 (AAV9) delivery ameliorates AKI exacerbation in Adh1KO mice with lethal endotoxemia. Our study supports the notion that ADH1 is critical for blockade of tubular apoptosis mediated by mitophagy, allowing the rapid identification and targeting of alcohol-metabolic route applicable to septic AKI.

Keywords:  Acute kidney injury; Alcohol dehydrogenase 1; Mitophagy; Sepsis

DOI:  https://doi.org/10.1016/j.yexcr.2023.113804
BMB Rep. 2023 Oct 11. pii: 5993. [Epub ahead of print]

C-reactive protein accelerates DRP1-mediated mitochondrial fission by modulating ERK1/2-YAP signaling in cardiomyocytes.

Suyeon Jin, Chan Joo Lee, Gibbeum Lim, Sungha Park, Sang-Hak Lee, Ji Hyung Chung, Jaewon Oh, Seok-Min Kang.

C-reactive protein (CRP) is an inflammatory marker and risk factor for atherosclerosis and cardiovascular diseases. However, the mechanism through which CRP induces myocardial damage remains unclear. This study aimed to determine how CRP damages cardiomyocytes via the change of mitochondrial dynamics and whether survivin, an anti-apoptotic protein, exerts a cardioprotective effect in this process. We treated H9c2 cardiomyocytes with CRP and found increased intracellular ROS production and shortened mitochondrial length. CRP treatment phosphorylated ERK1/2 and promoted increased expression, phosphorylation, and translocation of DRP1, a mitochondrial fission-related protein, from the cytoplasm to the mitochondria. The expression of mitophagy proteins PINK1 and PARK2 was also increased by CRP. YAP, a transcriptional regulator of PINK1 and PARK2, was also increased by CRP. Knockdown of YAP prevented CRP-induced increases in DRP1, PINK1, and PARK2. Furthermore, CRP-induced changes in the expression of DRP1 and increases in YAP, PINK1, and PARK2 were inhibited by ERK1/2 inhibition, suggesting that ERK1/2 signaling is involved in CRP-induced mitochondrial fission. We treated H9c2 cardiomyocytes with a recombinant TAT-survivin protein before CRP treatment, which reduced CRP-induced ROS accumulation and reduced mitochondrial fission. CRP-induced activation of ERK1/2 and increases in the expression and activity of YAP and its downstream mitochondrial proteins were inhibited by TAT-survivin. This study shows that mitochondrial fission occurs during CRPinduced cardiomyocyte damage and that the ERK1/2-YAP axis is involved in this process, and identifies that survivin alters these mechanisms to prevent CRP-induced mitochondrial damage.
Mol Cell Biochem. 2023 Oct 13.

Metformin modulates mitochondrial autophagy in renal tubular epithelial injury induced by high glucose via the Keap1/Nrf2 pathway.

Da Sun, Huimin Li, Yinke Du, Ying Chen, Li Yao, Lining Wang.

  The current study aimed to explore the role and underpinning molecular mechanisms of metformin in renal cellular injury induced by high glucose levels. Male C57BL/KsJ (db/db) and (db/m +) mice were utilized in this study. The experimental group was administered 1 mg/mL of metformin through drinking water. Renal tissues were harvested for hematoxylin and eosin (HE) staining, superoxide dismutase (SOD) activity detection, biochemical indices analysis, Western blotting, and qRT-PCR. HK-2 cells were utilized for Nrf2 siRNA transfection and to establish a high level of glucose-induced cell models. Metformin was administered at a concentration of 1 mmol/L in the experimental group. Cellular viability was assessed using CCK-8, whereas acridine orange (AO) staining and LC3-mitotracker co-localization staining were employed to evaluate autophagy. The expression of Nrf2, P21, LC3, PTEN-induced putative kinase 1 (PINK1), translocase of outer mitochondrial membrane 20 (TOMM20), and Kelch-like ECH-associated protein 1 (Keap1) were determined through Western blotting and qRT-PCR. Metformin mitigated renal tissue inflammatory damage in diabetic mice, as indicated by upregulated expression of Nrf2, PINK1, LC3, and TOMM20, and downregulated expression of Keap1 and P21. High level of glucose treatment in HK-2 cells resulted in decreased autophagy, and reduced expression of Nrf2, PINK1, LC3, and TOMM20 alongside elevated the expression of Keap1 and P21. Notably, metformin treatment partially counteracted these effects. Nrf2 knockdown intensified these phenomena in the high level of glucose-induced model. Protein-protein interaction network analysis indicated that Nrf2 could regulate the majority autophagy-related proteins via Keap1. Metformin modulates mitochondrial autophagy in high glucose-induced renal tubular epithelial senescence via the Keap1/Nrf2 pathway.

Keywords:  Autophagy; Diabetic nephropathy; Keap1-Nrf2; Metformin; Senescence

DOI:  https://doi.org/10.1007/s11010-023-04843-8
Int J Mol Sci. 2023 Oct 03. pii: 14867. [Epub ahead of print]24(19):

Genetic and Functional Modifications Associated with Ovarian Cancer Cell Aggregation and Limited Culture Conditions.

Joseph P Grieco, Stephanie L E Compton, Grace N Davis, Jack Guinan, Eva M Schmelz.

  The aggregation of cancer cells provides a survival signal for disseminating cancer cells; however, the underlying molecular mechanisms have yet to be elucidated. Using qPCR gene arrays, this study investigated the changes in cancer-specific genes as well as genes regulating mitochondrial quality control, metabolism, and oxidative stress in response to aggregation and hypoxia in our progressive ovarian cancer models representing slow- and fast-developing ovarian cancer. Aggregation increased the expression of anti-apoptotic, stemness, epithelial-mesenchymal transition (EMT), angiogenic, mitophagic, and reactive oxygen species (ROS) scavenging genes and functions, and decreased proliferation, apoptosis, metabolism, and mitochondrial content genes and functions. The incorporation of stromal vascular cells (SVF) from obese mice into the spheroids increased DNA repair and telomere regulatory genes that may represent a link between obesity and ovarian cancer risk. While glucose had no effect, glutamine was essential for aggregation and supported proliferation of the spheroid. In contrast, low glucose and hypoxic culture conditions delayed adhesion and outgrowth capacity of the spheroids independent of their phenotype, decreased mitochondrial mass and polarity, and induced a shift of mitochondrial dynamics towards mitophagy. However, these conditions did not reduce the appearance of polarized mitochondria at adhesion sites, suggesting that adhesion signals that either reversed mitochondrial fragmentation or induced mitobiogenesis can override the impact of low glucose and oxygen levels. Thus, the plasticity of the spheroids' phenotype supports viability during dissemination, allows for the adaptation to changing conditions such as oxygen and nutrient availability. This may be critical for the development of an aggressive cancer phenotype and, therefore, could represent druggable targets for clinical interventions.

Keywords:  aggregation; angiogenesis; glucose; hypoxia; metabolism; mitobiogenesis; mitophagy; ovarian cancer

DOI:  https://doi.org/10.3390/ijms241914867
J Transl Med. 2023 Oct 08. 21(1): 701

Knockdown of NR3C1 inhibits the proliferation and migration of clear cell renal cell carcinoma through activating endoplasmic reticulum stress-mitophagy.

Minbo Yan, Jinhua Wang, Haojie Wang, Jun Zhou, Hao Qi, Yaser Naji, Liangyu Zhao, Yuxin Tang, Yingbo Dai.

  BACKGROUND: Clear cell renal cell carcinoma (ccRCC) is closely associated with steroid hormones and their receptors affected by lipid metabolism. Recently, there has been growing interest in the carcinogenic role of NR3C1, the sole gene responsible for encoding glucocorticoid receptor. However, the specific role of NR3C1 in ccRCC remains unclear. The present study was thus developed to explore the underlying mechanism of NR3C1's carcinogenic effects in ccRCC.METHODS: Expression of NR3C1 was verified by various tumor databases and assessed using RT-qPCR and western blot. Stable transfected cell lines of ccRCC with NR3C1 knockdown were constructed, and a range of in vitro and in vivo experiments were performed to examine the effects of NR3C1 on ccRCC proliferation and migration. Transcriptomics and lipidomics sequencing were then conducted on ACHN cells, which were divided into control and sh-NR3C1 group. Finally, the sequencing results were validated using transmission electron microscopy, mitochondrial membrane potential assay, immunofluorescence co-localization, cell immunofluorescent staining, and Western blot. The rescue experiments were designed to investigate the relationship between endoplasmic reticulum stress (ER stress) and mitophagy in ccRCC cells after NR3C1 knockdown, as well as the regulation of their intrinsic signaling pathways.
RESULTS: The expression of NR3C1 in ccRCC cells and tissues was significantly elevated. The sh-NR3C1 group, which had lower levels of NR3C1, exhibited a lower proliferation and migration capacity of ccRCC than that of the control group (P < 0.05). Then, lipidomic and transcriptomic sequencing showed that lipid metabolism disorders, ER stress, and mitophagy genes were enriched in the sh-NR3C1 group. Finally, compared to the control group, ER stress and mitophagy were observed in the sh-NR3C1 group, while the expression of ATF6, CHOP, PINK1, and BNIP3 was also up-regulated (P < 0.05). Furthermore, Ceapin-A7, an inhibitor of ATF6, significantly down-regulated the expression of PINK1 and BNIP3 (P < 0.05), and significantly increased the proliferation and migration of ccRCC cells (P < 0.05).
CONCLUSIONS: This study confirms that knockdown of NR3C1 activates ER stress and induces mitophagy through the ATF6-PINK1/BNIP3 pathway, resulting in reduced proliferation and migration of ccRCC. These findings indicate potential novel targets for clinical treatment of ccRCC.

Keywords:  Clear cell renal cell carcinoma; Endoplasmic reticulum stress; Mitophgay; NR3C1

DOI:  https://doi.org/10.1186/s12967-023-04560-2
Life Sci. 2023 Oct 11. pii: S0024-3205(23)00797-X. [Epub ahead of print]333 122162

Activation of the Nrf-2 pathway by pinocembrin safeguards vertebral endplate chondrocytes against apoptosis and degeneration caused by oxidative stress.

Heran Wang, Xiaoyang Liu, Heng Yang, Xingzhi Jing, Wenchao Wang, Xiaodong Liu, Bofei Zhang, Xin Liu, Yuandong Shao, Xingang Cui.

  AIM: The occurrence and progression of intervertebral disc degeneration (IDD) are significantly influenced by the cartilaginous endplate (CEP). Pinocembrin (PIN), a type of flavonoid present in propolis and botanicals, demonstrates both antioxidant and anti-inflammatory characteristics, which could potentially be utilized in management. Therefore, it is crucial to investigate how PIN protects against CEP degeneration and its mechanisms, offering valuable insights for IDD therapy.MATERIALS AND METHODS: To investigate the protective impact of PIN in vivo, we created the IDD mouse model through bilateral facet joint transection. In vitro, an IDD pathological environment was mimicked by applying TBHP to treat endplate chondrocytes.
KEY FINDINGS: In vivo, compared with the IDD group, the mouse in the PIN group effectively mitigates IDD progression and CEP calcification. In vitro, the activation of the Nrf-2 pathway improves the process of Parkin-mediated autophagy in mitochondria and decreases ferroptosis in chondrocytes. This enhancement promotes cell survival by addressing the imbalance of redox during pathological conditions related to IDD. Knocking down Nrf-2 with siRNA fails to provide protection to endplate chondrocytes against apoptosis and degeneration.
SIGNIFICANCE: The Nrf-2-mediated activation of mitochondrial autophagy and suppression of ferroptosis play a crucial role in safeguarding against oxidative stress-induced degeneration and calcification of CEP through the protective function of PIN. To sum up, this research offers detailed explanations about how PIN can protect against apoptosis and calcification in CEP, providing valuable information about the development of IDD and suggesting possible treatment approaches.

Keywords:  Apoptosis; Ferroptosis; Intervertebral disc degeneration; Mitophagy; Nrf-2; Pinocembrin

DOI:  https://doi.org/10.1016/j.lfs.2023.122162
Int J Mol Sci. 2023 Sep 27. pii: 14624. [Epub ahead of print]24(19):

The Pro-Oncogenic Protein IF1 Promotes Proliferation of Anoxic Cancer Cells during Re-Oxygenation.

Riccardo Righetti, Silvia Grillini, Valentina Del Dotto, Anna Costanzini, Francesca Liuzzi, Claudia Zanna, Gianluca Sgarbi, Giancarlo Solaini, Alessandra Baracca.

  Cancer cells overexpress IF1, the endogenous protein that inhibits the hydrolytic activity of ATP synthase when mitochondrial membrane potential (ΔμH+) falls, as in ischemia. Other roles have been ascribed to IF1, but the associated molecular mechanisms are still under debate. We investigated the ability of IF1 to promote survival and proliferation in osteosarcoma and colon carcinoma cells exposed to conditions mimicking ischemia and reperfusion, as occurs in vivo, particularly in solid tumors. IF1-silenced and parental cells were exposed to the FCCP uncoupler to collapse ΔμH+ and the bioenergetics of cell models were validated. All the uncoupled cells preserved mitochondrial mass, but the implemented mechanisms differed in IF1-expressing and IF1-silenced cells. Indeed, the membrane potential collapse and the energy charge preservation allowed an increase in both mitophagy and mitochondrial biogenesis in IF1-expressing cells only. Interestingly, the presence of IF1 also conferred a proliferative advantage to cells highly dependent on oxidative phosphorylation when the uncoupler was washed out, mimicking cell re-oxygenation. Overall, our results indicate that IF1, by allowing energy preservation and promoting mitochondrial renewal, can favor proliferation of anoxic cells and tumor growth. Therefore, hindering the action of IF1 may be promising for the therapy of tumors that rely on oxidative phosphorylation for energy production.

Keywords:  143B osteosarcoma cells; ATP synthase; HCT116 colon carcinoma cells; anoxia; autophagy; biogenesis; metabolism; mitochondria; mitophagy; oxidative phosphorylation

DOI:  https://doi.org/10.3390/ijms241914624
Open Med (Wars). 2023 ;18(1): 20230798

Silencing USP19 alleviates cigarette smoke extract-induced mitochondrial dysfunction in BEAS-2B cells by targeting FUNDC1.

Yanjing You, Huijuan Wang, Qing Wang, Zongyang Yu, Zhongquan Zhao, Liying Zhuang, Shengyuan Zeng, Jinyang Zheng, Wen Wen.

  Chronic obstructive pulmonary disease (COPD) is commonly caused by smoking. FUN14 domain-containing protein 1 (FUNDC1) plays a fundamental role in mitochondrial autophagy and apoptosis in cigarette smoke extract (CSE)-treated BEAS-2B cells. The present study investigated the mechanism of action of FUNDC1 in mitochondrial dysfunction and apoptosis in CSE-treated BEAS-2B cells. The interaction between ubiquitin-specific peptidase 19 (USP19) and FUNDC1 was analyzed using co-immunoprecipitation. Effects of USP19 knockdown and/or FUNDC1 overexpression on the survival, apoptosis, mitochondrial membrane potential, and oxygen consumption rate (OCR) of BEAS-2B cells treated with 15% CSE were determined. In BEAS-2B cells, CSE inhibited cell survival, promoted apoptosis, increased the expression of USP19 and FUNDC1, increased the ratio of LC3 II to LC3 I (LC3 II/I), and decreased mitochondrial membrane potential and TOM20 levels. In CSE-treated BEAS-2B cells, USP19 knockdown reduced FUNDC1 and LC3 II/I, increased the levels of TOM20, improved cell survival, mitochondrial membrane potential, and OCR, and inhibited apoptosis. USP19 deubiquitinates FUNDC1. FUNDC1 overexpression inhibited the effect of USP19 knockdown in CSE-treated BEAS-2B cells. Overall, decreasing USP19 expression alleviates CSE-induced mitochondrial dysfunction in BEAS-2B cells by downregulating FUNDC1, providing novel insights into the molecular mechanism of FUNDC1 regulation in COPD.

Keywords:  FUNDC1; USP19; chronic obstructive pulmonary disease; cigarette smoke extract; mitochondrial function

DOI:  https://doi.org/10.1515/med-2023-0798
Dalton Trans. 2023 Oct 13.

Inducing and monitoring mitochondrial pH changes with an iridium(III) complex via two-photon lifetime imaging.

Meng Hu, Xin-Lan Zhou, Tian-Xin Xiao, Liang Hao, Yi Li.

Real-time monitoring of mitochondrial dynamic changes plays a key role in the development of mitochondria-targeted anticancer theranostic agents. In this work, a pH-responsive and mitochondria-targeted cyclometalated iridium(III) complex MitoIr-NH has been explored as a novel anticancer agent. MitoIr-NH displayed pH-responsive phosphorescence intensity and lifetime, accumulated in mitochondria, showed higher antiproliferative activity and induced a series of mitochondria-related events. Moreover, MitoIr-NH could simultaneously induce mitophagy and quantitatively monitor mitochondrial pH changes through two-photon phosphorescence lifetime imaging microscopy (TPPLIM) in a real-time manner.

DOI: https://doi.org/10.1039/d3dt02541a
Adv Sci (Weinh). 2023 Oct 11. e2303561

FBXO7 Confers Mesenchymal Properties and Chemoresistance in Glioblastoma by Controlling Rbfox2-Mediated Alternative Splicing.

Shangbiao Li, Yanwen Chen, Yuxin Xie, Hongchao Zhan, Yu Zeng, Kunlin Zeng, Li Wang, Ziling Zhan, Cuiying Li, Liqian Zhao, Xiaoxia Chen, Yujing Tan, Zhongyong Wang, Junguo Bu, Ye Song, Fan Deng, Aidong Zhou.

  Mesenchymal glioblastoma (GBM) is highly resistant to radio-and chemotherapy and correlates with worse survival outcomes in GBM patients; however, the underlying mechanism determining the mesenchymal phenotype remains largely unclear. Herein, it is revealed that FBXO7, a substrate-recognition component of the SCF complex implicated in the pathogenesis of Parkinson's disease, confers mesenchymal properties and chemoresistance in GBM by controlling Rbfox2-mediated alternative splicing. Specifically, FBXO7 ubiquitinates Rbfox2 Lys249 through K63-linked ubiquitin chains upon arginine dimethylation at Arg341 and Arg441 by PRMT5, leading to Rbfox2 stabilization. FBXO7 controls Rbfox2-mediated splicing of mesenchymal genes, including FoxM1, Mta1, and Postn. FBXO7-induced exon Va inclusion of FoxM1 promotes FoxM1 phosphorylation by MEK1 and nuclear translocation, thereby upregulates CD44, CD9, and ID1 levels, resulting in GBM stem cell self-renewal and mesenchymal transformation. Moreover, FBXO7 is stabilized by temozolomide, and FBXO7 depletion sensitizes tumor xenografts in mice to chemotherapy. The findings demonstrate that the FBXO7-Rbfox2 axis-mediated splicing contributes to mesenchymal transformation and tumorigenesis, and targeting FBXO7 represents a potential strategy for GBM treatment.

Keywords:  FBXO7; alternative splicing; chemoresistance; glioblastoma; mesenchymal transformation

DOI:  https://doi.org/10.1002/advs.202303561
Naunyn Schmiedebergs Arch Pharmacol. 2023 Oct 09.

Molecular mechanisms involved in doxorubicin-induced cardiotoxicity: A bibliometrics analysis by VOSviewer.

Fatemeh Yarmohammadi, A Wallace Hayes, Gholamreza Karimi.

  Doxorubicin is a potent chemotherapeutic agent that can cause cardiotoxicity. Many documents (more than 14,000) have been published in the area of doxorubicin-induced cardiotoxicity (DIC) since 1970. A comprehensive bibliographic analysis of author keywords was used to describe better and understand the molecular mechanisms involved in DIC. The objective was to consider the state of the author keywords of research on the molecular mechanisms involved in DIC based on a bibliometrics study of articles published over the past fifty years. A bibliometrics analysis was conducted using VOSviewer with data collected from the Web of Science Core Collection database of over 14,000 documents (from 1970 to July 19, 2023). Using scientific publications retrieved about DIC, author keywords were assessed at the scientific field level. The current study showed that the annual number of DIC-related publications has increased over the past 50 years. The Journal of Clinical Oncology is the leading journal in this field. The top cited DIC document was published in 2004. The top keywords with high frequency were "doxorubicin," "cardiotoxicity," and "adriamycin." According to the results of this study, the most common mechanisms involved in DIC were as follows oxidative stress, apoptosis, inflammation, autophagy, mitophagy, endoplasmic reticulum stress, pyroptosis, and ferroptosis. The highest occurrences of regulators-related author keywords were "AKT," "Sirt1," and "AMPK." Based on the findings, oxidative stress, apoptosis, inflammation, autophagy, mitophagy, endoplasmic reticulum stress, pyroptosis, and ferroptosis were hot research mechanisms of DIC from 1970 to July 19, 2023.

Keywords:  Adriamycin; Apoptosis; Author-keywords; Autophagy; Inflammation; Mitophagy

DOI:  https://doi.org/10.1007/s00210-023-02773-2