bims-mitlys 2021-07-04 papers

bims-mitlys

Biomed News

on Mitochondria and Lysosomes

Issue of 2021–07–04
eightteen papers selected by
Nicoletta Plotegher, University of Padova

Nicotine Causes Mitochondrial Dynamics Imbalance and Apoptosis Through ROS Mediated Mitophagy Impairment in Cardiomyocytes.
Ubiquitination and receptor-mediated mitophagy converge to eliminate oxidation-damaged mitochondria during hypoxia.
Mito-Tempo suppresses autophagic flux via the PI3K/Akt/mTOR signaling pathway in neuroblastoma SH-SY5Y cells.
Mechanisms of organelle elimination for lens development and differentiation.
Effect of Chronic Stress Present in Fibroblasts Derived from Patients with a Sporadic Form of AD on Mitochondrial Function and Mitochondrial Turnover.
Endoplasmic reticulum-mitochondria coupling increases during doxycycline-induced mitochondrial stress in HeLa cells.
Melatonin Represses Mitophagy to Protect Mouse Granulosa Cells from Oxidative Damage.
Mitophagy coordinates the mitochondrial unfolded protein response to attenuate inflammation-mediated myocardial injury.
Wdfy3 regulates glycophagy, mitophagy, and synaptic plasticity.
Monitoring Mitophagy via the FRET Mechanism: Visualizing Mitochondria, Lysosomes, and Autolysosomes in Three Different Sets of Fluorescence Signals.
Protective Effect of Optic Atrophy 1 on Cardiomyocyte Oxidative Stress: Roles of Mitophagy, Mitochondrial Fission, and MAPK/ERK Signaling.
Disturbed Mitochondria-Lysosome Crosstalk in GBA1-Associated Parkinson's Disease.
Acid ceramidase improves mitochondrial function and oxidative stress in Niemann-Pick type C disease by repressing STARD1 expression and mitochondrial cholesterol accumulation.
Dystrophin deficiency disrupts muscle clock expression and mitochondrial quality control in mdx mice.
Amino Acid-Mediated Intracellular Ca2+ Rise Modulates mTORC1 by Regulating the TSC2-Rheb Axis through Ca2+/Calmodulin.
Coenzyme Q10 ameliorates BPA-induced apoptosis by regulating autophagy-related lysosomal pathways.
Nrf2/ARE Activators Improve Memory in Aged Mice via Maintaining of Mitochondrial Quality Control of Brain and the Modulation of Gut Microbiome.
The molecular mechanism underlying mitophagy-mediated hippocampal neuron apoptosis in diabetes-related depression.

Front Physiol. 2021 ;12 650055

Nicotine Causes Mitochondrial Dynamics Imbalance and Apoptosis Through ROS Mediated Mitophagy Impairment in Cardiomyocytes.

Ting-Ting Meng, Wei Wang, Fan-Liang Meng, Shu-Ya Wang, Hui-Hui Wu, Jia-Min Chen, Yan Zheng, Guang-Xin Wang, Mao-Xiu Zhang, Ying Li, Guo-Hai Su.

  Nicotine contained in traditional cigarettes, hookahs, and e-cigarettes is an important risk factor for cardiovascular disease. Our previous study showed that macroautophagic flux impairment occurred under nicotine stimulation. However, whether nicotine influences mitochondrial dynamics in neonatal rat ventricular myocytes (NRVMs) is unclear. The purpose of this study was to explore the effects and potential mechanism of nicotine on mitophagy, mitochondrial dynamics, apoptosis, and the relationship between these processes in NRVMs. Our results showed that nicotine exposure increased mitochondria-derived superoxide production, decreased mitochondrial membrane potential, and impaired PINK1/Parkin-mediated mitophagic flux in NRVMs. Interestingly, nicotine significantly promoted dynamin-related protein 1 (Drp1)-mediated mitochondrial fission and suppressed mitofusin (MFN)-mediated fusion, which was also observed in the bafilomycin A1-treated group. These results suggest that mitophagic flux impairment may contribute to Drp-1-mediated mitochondrial fission. Finally, nicotine caused excessive mitochondrial fission and contributed to apoptosis, which could be alleviated by mdivi-1, an inhibitor of Drp1. In addition to CTSB, as we previously reported, the enzyme activity of cathepsin L (CTSL) was also decreased in lysosomes after stimulation with nicotine, which may be the main cause of the hindered mitophagic flux induced by nicotine in NRVMs. Pretreatment with Torin 1, which is an inhibitor of mTOR, activated CTSL and ameliorated nicotine-induced mTOR activation and mitophagy impairment, decreased mitochondria-derived superoxide production, and blunted mitochondrial fission and apoptosis. Pretreatment with the ROS scavenger N-acetyl-cysteine (NAC) or inhibitors of p38 and JNK, which could also alleviate mitophagy impairment, exhibited similar effects as Torin1 on mitochondria. Taken together, our study demonstrated that nicotine treatment may lead to an increase in Drp1-mediated mitochondrial fission by blocking mitophagic flux by weakening the enzyme activity of CTSL and activating the ROS/p38/JNK signaling pathway. Excessive mitochondrial fission induced by nicotine ultimately leads to apoptosis. Torin1 restored the decreased CTSL enzyme activity by removing excessive ROS and alleviated the effects of nicotine on mitophagic flux, mitochondrial dynamics, and apoptosis. These results may provide new evidence on the relationship between mitophagic flux and mitochondrial dynamics and new perspectives on nicotine's effects on mitochondrial dynamics in cardiomyocytes.

Keywords:  CSTL; apoptosis; mitochondria dynamics; mitophagy; nicotine

DOI:  https://doi.org/10.3389/fphys.2021.650055
Redox Biol. 2021 Jun 17. pii: S2213-2317(21)00206-8. [Epub ahead of print]45 102047

Ubiquitination and receptor-mediated mitophagy converge to eliminate oxidation-damaged mitochondria during hypoxia.

Prasad Sulkshane, Jonathan Ram, Anita Thakur, Noa Reis, Oded Kleifeld, Michael H Glickman.

  The contribution of the Ubiquitin-Proteasome System (UPS) to mitophagy has been largely attributed to the E3 ubiquitin ligase Parkin. Here we show that in response to the oxidative stress associated with hypoxia or the hypoxia mimic CoCl2, the damaged and fragmented mitochondria are removed by Parkin-independent mitophagy. Mitochondria isolated from hypoxia or CoCl2-treated cells exhibited extensive ubiquitination, predominantly Lysine 48-linked and involves the degradation of key mitochondrial proteins such as the mitofusins MFN1/2, or the import channel component TOM20. Reflecting the critical role of mitochondrial protein degradation, proteasome inhibition blocked CoCl2-induced mitophagy. The five conserved ubiquitin-binding autophagy receptors (p62, NDP52, Optineurin, NBR1, TAX1BP1) were dispensable for the ensuing mitophagy, suggesting that the mitophagy step itself was independent of ubiquitination. Instead, the expression of two ubiquitin-independent mitophagy receptor proteins BNIP3 and NIX was induced by hypoxia or CoCl2-treatment followed by their recruitment to the oxidation-damaged mitochondria. By employing BNIP3/NIX double knockout and DRP1-null cell lines, we confirmed that mitochondrial clearance relies on DRP1-dependent mitochondrial fragmentation and BNIP3/NIX-mediated mitophagy. General antioxidants such as N-Acetyl Cysteine (NAC) or the mitochondria-specific Mitoquinone prevented HIF-1α stabilization, ameliorated hypoxia-related mitochondrial oxidative stress, and suppressed mitophagy. We conclude that the UPS and receptor-mediated autophagy converge to eliminate oxidation-damaged mitochondria.

Keywords:  HIF-1α; Hypoxia; Mitochondria; Mitophagy; Oxidative stress; Proteasome; Ubiquitin

DOI:  https://doi.org/10.1016/j.redox.2021.102047
Heliyon. 2021 Jun;7(6): e07310

Mito-Tempo suppresses autophagic flux via the PI3K/Akt/mTOR signaling pathway in neuroblastoma SH-SY5Y cells.

Sirirak Mukem, Tipsuda Thongbuakaew, Kanjana Khornchatri.

  The generation of excessive mitochondrial reactive oxygen species (mtROS) is associated with glutamate-stimulated neurotoxicity and pathogenesis of Alzheimer's disease (AD). Impaired mitochondrial function is accompanied with oxidative stress that is a significant contributor to initiate autophagy, but the underlying mechanisms are not fully understood. The present study aimed to investigate the neuroprotective effects of Mito-Tempo on glutamate-induced neuroblastoma SH-SY5Y cell toxicity. SH-SY5Y cells were treated with 100 μM glutamate in the presence or absence of 50 and 100 μM Mito-Tempo for 24 h. Changes in cell viability were measured by MTT assay. Cytotoxicity and intracellular ROS accumulation were also evaluated using lactate dehydrogenase (LDH) activity assay and 2,7-dichlorofluorescein diacetate (DCFDA) Reactive Oxygen Species Assay kit, respectively. Mitochondrial membrane potential was analyzed by tetraethylbenzimidazoly-lcarbocyanine iodide (JC-1) staining. Expression of PI3K/AKT/mTOR pathway and autophagy markers, including LC3 (LC3-I/-II) and p62 (SQSTM1) were performed using Western blot analysis. Our results demonstrated that glutamate-exposed cells significantly increased cellular oxidative stress by enhancing ROS production. Glutamate treatment also increased LDH release follows the loss of mitochondrial membrane potential, caused cell viability loss. Treatment with Mito-Tempo not only attenuated the generation of ROS and improved mitochondrial membrane potential but also reduced the neurotoxicity of glutamate in a concentration-dependent manner, which leads to increased cell viability and decreased LDH release. Mito-Tempo has a greater protective effect by enhancing superoxide dismutase (SOD) activity and PI3K/AKT/mTOR phosphorylation. Moreover, Mito-Tempo treatment altered the autophagy process resulting in the decline in the ratio of the autophagy markers LC3-I/-II and p62 (SQSTM1). We propose that Mito-Tempo can improve neuronal properties against glutamate cytotoxicity through its direct free radical scavenging activity and inhibit excessive autophagy signaling pathway, therefore, allow for further studies to investigate the therapeutic potentials of Mito-Tempo in animal disease models and human.

Keywords:  Autophagy; Excitotoxicity; Glutamate; Mito-Tempo; Mitochondrial dysfunction; Oxidative stress

DOI:  https://doi.org/10.1016/j.heliyon.2021.e07310
Exp Eye Res. 2021 Jun 29. pii: S0014-4835(21)00248-7. [Epub ahead of print] 108682

Mechanisms of organelle elimination for lens development and differentiation.

Lisa Brennan, Joshua Disatham, Marc Kantorow.

  A hallmark feature of lens development and differentiation is the complete elimination of organelles from the center of the eye lens. A long unanswered question in lens biology is what are the mechanisms that control the elimination of organelles during the terminal remodeling program to form mature lens fiber cells? Recent advances have expanded our understanding of these mechanisms including newly discovered signaling pathways, proteasomal regulators, autophagy proteins, transcription factors and the hypoxic environment of the lens itself. These recent discoveries suggest that distinct mechanisms coordinate the elimination of the nucleus, mitochondria, endoplasmic reticulum and Golgi apparatus during lens fiber cell differentiation. Since regulation of organelle number and distribution is also a feature of the terminal remodeling programs of more complex cell-types and tissues, these advances are likely to impact a wide-variety of fields.

Keywords:  Autophagy; Chromatin; Development; Differentiation; Endoplasmic reticulum; Golgi apparatus; Hypoxia; Lens; Mitochondria; Nucleus; Organelle regulation; Transcriptional regulation

DOI:  https://doi.org/10.1016/j.exer.2021.108682
Antioxidants (Basel). 2021 Jun 10. pii: 938. [Epub ahead of print]10(6):

Effect of Chronic Stress Present in Fibroblasts Derived from Patients with a Sporadic Form of AD on Mitochondrial Function and Mitochondrial Turnover.

Karolina Drabik, Dominika Malińska, Karolina Piecyk, Grażyna Dębska-Vielhaber, Stefan Vielhaber, Jerzy Duszyński, Joanna Szczepanowska.

  Although the sporadic form of Alzheimer's disease (AD) is the prevalent form, the cellular events underlying the disease pathogenesis have not been fully characterized. Accumulating evidence points to mitochondrial dysfunction as one of the events responsible for AD progression. We investigated mitochondrial function in fibroblasts collected from patients diagnosed with the sporadic form of AD (sAD), placing a particular focus on mitochondrial turnover. We measured mitochondrial biogenesis and autophagic clearance, and evaluated the presence of bioenergetic stress in sAD cells. The mitochondrial turnover was clearly lower in the fibroblasts from sAD patients than in the fibroblasts from the control subjects, and the levels of many proteins regulating mitochondrial biogenesis, autophagy and mitophagy were decreased in patient cells. Additionally, the sAD fibroblasts had slightly higher mitochondrial superoxide levels and impaired antioxidant defense. Mitochondrial turnover undergoes feedback regulation through mitochondrial retrograde signaling, which is responsible for the maintenance of optimal mitochondrial functioning, and mitochondria-derived ROS participate as signaling molecules in this process. Our results showed that in sAD patients cells, there is a shift in the balance of mitochondrial function, possibly in response to the presence of cellular stress related to disease development.

Keywords:  Alzheimer’s disease; mitochondria; mitochondrial biogenesis; mitochondrial retrograde signaling; mitophagy; reactive oxygen species

DOI:  https://doi.org/10.3390/antiox10060938
Cell Death Dis. 2021 Jun 28. 12(7): 657

Endoplasmic reticulum-mitochondria coupling increases during doxycycline-induced mitochondrial stress in HeLa cells.

Camila Lopez-Crisosto, Alexis Díaz-Vegas, Pablo F Castro, Beverly A Rothermel, Roberto Bravo-Sagua, Sergio Lavandero.

Subcellular organelles communicate with each other to regulate function and coordinate responses to changing cellular conditions. The physical-functional coupling of the endoplasmic reticulum (ER) with mitochondria allows for the direct transfer of Ca2+ between organelles and is an important avenue for rapidly increasing mitochondrial metabolic activity. As such, increasing ER-mitochondrial coupling can boost the generation of ATP that is needed to restore homeostasis in the face of cellular stress. The mitochondrial unfolded protein response (mtUPR) is activated by the accumulation of unfolded proteins in mitochondria. Retrograde signaling from mitochondria to the nucleus promotes mtUPR transcriptional responses aimed at restoring protein homeostasis. It is currently unknown whether the changes in mitochondrial-ER coupling also play a role during mtUPR stress. We hypothesized that mitochondrial stress favors an expansion of functional contacts between mitochondria and ER, thereby increasing mitochondrial metabolism as part of a protective response. Hela cells were treated with doxycycline, an antibiotic that inhibits the translation of mitochondrial-encoded proteins to create protein disequilibrium. Treatment with doxycycline decreased the abundance of mitochondrial encoded proteins while increasing expression of CHOP, C/EBPβ, ClpP, and mtHsp60, markers of the mtUPR. There was no change in either mitophagic activity or cell viability. Furthermore, ER UPR was not activated, suggesting focused activation of the mtUPR. Within 2 h of doxycycline treatment, there was a significant increase in physical contacts between mitochondria and ER that was distributed throughout the cell, along with an increase in the kinetics of mitochondrial Ca2+ uptake. This was followed by the rise in the rate of oxygen consumption at 4 h, indicating a boost in mitochondrial metabolic activity. In conclusion, an early phase of the response to doxycycline-induced mitochondrial stress is an increase in mitochondrial-ER coupling that potentiates mitochondrial metabolic activity as a means to support subsequent steps in the mtUPR pathway and sustain cellular adaptation.

DOI: https://doi.org/10.1038/s41419-021-03945-9
Biomolecules. 2021 Jun 30. pii: 968. [Epub ahead of print]11(7):

Melatonin Represses Mitophagy to Protect Mouse Granulosa Cells from Oxidative Damage.

Yi Jiang, Ming Shen, Yuanyuan Chen, Yinghui Wei, Jingli Tao, Honglin Liu.

  Various environmental stimuli, including oxidative stress, could lead to granulosa cell (GC) death through mitophagy. Recently, it was reported that melatonin (MEL) has a significant effect on GC survival during oxidative damage. Here, we found that MEL inhibited oxidative stress-induced mitophagy to promote GC survival. The loss of cell viability upon H2O2 exposure was significantly restored after MEL treatment. Concomitantly, MEL inhibited the activation of mitophagy during oxidative stress. Notably, blocking mitophagy repressed GC death caused by oxidative stress. However, MEL cannot further restore viability of cells treated with mitophagy inhibitor. Moreover, PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine/threonine-protein kinase, was inhibited by MEL during oxidative stress. As a result, the E3 ligase Parkin failed to translocate to mitochondria, leading to impaired mitochondria clearance. Using RNAi to knock down PINK1 expression, we further verified the role of the MEL-PINK1-Parkin (MPP) pathway in maintaining GC survival by suppressing mitophagy. Our findings not only clarify the protective mechanisms of MEL against oxidative damage in GCs, but also extend the understanding about how circadian rhythms might influence follicles development in the ovary. These findings reveal a new mechanism of melatonin in defense against oxidative damage to GCs by repressing mitophagy, which may be a potential therapeutic target for anovulatory disorders.

Keywords:  PINK1-Parkin pathway; granulosa cells; melatonin; mitophagy; oxidative damage

DOI:  https://doi.org/10.3390/biom11070968
Redox Biol. 2021 Jun 18. pii: S2213-2317(21)00208-1. [Epub ahead of print]45 102049

Mitophagy coordinates the mitochondrial unfolded protein response to attenuate inflammation-mediated myocardial injury.

Yue Wang, Heinrich Jasper, Sam Toan, David Muid, Xing Chang, Hao Zhou.

  Mitochondrial dysfunction is a fundamental challenge in septic cardiomyopathy. Mitophagy and the mitochondrial unfolded protein response (UPRmt) are the predominant stress-responsive and protective mechanisms involved in repairing damaged mitochondria. Although mitochondrial homeostasis requires the coordinated actions of mitophagy and UPRmt, their molecular basis and interactive actions are poorly understood in sepsis-induced myocardial injury. Our investigations showed that lipopolysaccharide (LPS)-induced sepsis contributed to cardiac dysfunction and mitochondrial damage. Although both mitophagy and UPRmt were slightly activated by LPS in cardiomyocytes, their endogenous activation failed to prevent sepsis-mediated myocardial injury. However, administration of urolithin A, an inducer of mitophagy, obviously reduced sepsis-mediated cardiac depression by normalizing mitochondrial function. Interestingly, this beneficial action was undetectable in cardiomyocyte-specific FUNDC1 knockout (FUNDC1CKO) mice. Notably, supplementation with a mitophagy inducer had no impact on UPRmt, whereas genetic ablation of FUNDC1 significantly upregulated the expression of genes related to UPRmt in LPS-treated hearts. In contrast, enhancement of endogenous UPRmt through oligomycin administration reduced sepsis-mediated mitochondrial injury and myocardial dysfunction; this cardioprotective effect was imperceptible in FUNDC1CKO mice. Lastly, once UPRmt was inhibited, mitophagy-mediated protection of mitochondria and cardiomyocytes was partly blunted. Taken together, it is plausible that endogenous UPRmt and mitophagy are slightly activated by myocardial stress and they work together to sustain mitochondrial performance and cardiac function. Endogenous UPRmt, a downstream signal of mitophagy, played a compensatory role in maintaining mitochondrial homeostasis in the case of mitophagy inhibition. Although UPRmt activation had no negative impact on mitophagy, UPRmt inhibition compromised the partial cardioprotective actions of mitophagy. This study shows how mitophagy modulates UPRmt to attenuate inflammation-related myocardial injury and suggests the potential application of mitophagy and UPRmt targeting in the treatment of myocardial stress.

Keywords:  FUN14 domain-containing 1; Inflammation; Mitochondrial unfolded protein response; Mitophagy; Septic cardiomyopathy

DOI:  https://doi.org/10.1016/j.redox.2021.102049
J Cereb Blood Flow Metab. 2021 Jun 29. 271678X211027384

Wdfy3 regulates glycophagy, mitophagy, and synaptic plasticity.

Eleonora Napoli, Alexios A Panoutsopoulos, Patricia Kysar, Nathaniel Satriya, Kira Sterling, Bradley Shibata, Denise Imai, David N Ruskin, Konstantinos S Zarbalis, Cecilia Giulivi.

  Autophagy is essential to cell function, as it enables the recycling of intracellular constituents during starvation and in addition functions as a quality control mechanism by eliminating spent organelles and proteins that could cause cellular damage if not properly removed. Recently, we reported on Wdfy3's role in mitophagy, a clinically relevant macroautophagic scaffold protein that is linked to intellectual disability, neurodevelopmental delay, and autism spectrum disorder. In this study, we confirm our previous report that Wdfy3 haploinsufficiency in mice results in decreased mitophagy with accumulation of mitochondria with altered morphology, but expanding on that observation, we also note decreased mitochondrial localization at synaptic terminals and decreased synaptic density, which may contribute to altered synaptic plasticity. These changes are accompanied by defective elimination of glycogen particles and a shift to increased glycogen synthesis over glycogenolysis and glycophagy. This imbalance leads to an age-dependent higher incidence of brain glycogen deposits with cerebellar hypoplasia. Our results support and further extend Wdfy3's role in modulating both brain bioenergetics and synaptic plasticity by including glycogen as a target of macroautophagic degradation.

Keywords:  Glycogen; brain; electron microscopy; mitochondria; synapses

DOI:  https://doi.org/10.1177/0271678X211027384
Anal Chem. 2021 Jun 28.

Monitoring Mitophagy via the FRET Mechanism: Visualizing Mitochondria, Lysosomes, and Autolysosomes in Three Different Sets of Fluorescence Signals.

Qingqing Lu, Wenpeng Li, Kaiyuan Chen, Minggang Tian.

Mitophagy is a vital biological process playing central roles in the regulation of metabolic activity and quality control of mitochondria. The presented dual-color fluorescent probes to directly monitor mitophagy were based on the optical response to pH change during mitophagy, but pH fluctuation may lead to interference. To overcome this, herein, two fluorescent probes (G-Mito, R-Lyso) were rationally designed to visualize mitophagy directly in a dual-color manner, relying on the Förster resonance energy transfer (FRET) process for the first time. Green emissive G-Mito targeted and anchored the mitochondria via reaction with protein thiols. Red-emissive R-Lyso exclusively targeted lysosomes. Live cells loaded with the two probes demonstrated strong fluorescence in only the green channel with excitation at 405 nm. After mitophagy, G-Mito in mitochondria was delivered into the lysosomes, and red fluorescence evidently increased due to the FRET process. With the probes, mitochondria, lysosomes, and autolysosomes could be discriminatively visualized in three different sets of signals. Mitophagy induced by starvation and in normal physiological status were successfully observed. The probes revealed that a certain amount of H2O2 could induce mitophagy. We expect that the two probes can serve as molecular tools for validation of mitophagy and promote the development of related areas.

DOI: https://doi.org/10.1021/acs.analchem.1c01237
Oxid Med Cell Longev. 2021 ;2021 3726885

Protective Effect of Optic Atrophy 1 on Cardiomyocyte Oxidative Stress: Roles of Mitophagy, Mitochondrial Fission, and MAPK/ERK Signaling.

Yue Wang, Zhihua Han, Zuojun Xu, Junfeng Zhang.

Myocardial infarction is associated with oxidative stress and mitochondrial damage. However, the regulatory mechanisms underlying cardiomyocyte oxidative stress during myocardial infarction are not fully understood. In the present study, we explored the cardioprotective action of optic atrophy 1- (Opa1-) mediated mitochondrial autophagy (mitophagy) in oxidative stress-challenged cardiomyocytes, with a focus on mitochondrial homeostasis and the MAPK/ERK pathway. Our results demonstrated that overexpression of Opa1 in cultured rat H9C2 cardiomyocytes, a procedure that stimulates mitophagy, attenuates oxidative stress and increases cellular antioxidant capacity. Activation of Opa1-mediated mitophagy suppressed cardiomyocyte apoptosis by downregulating Bax, caspase-9, and caspase-12 and upregulating Bcl-2 and c-IAP. Using mitochondrial tracker staining and a reactive oxygen species indicator, our assays showed that Opa1-mediated mitophagy attenuated mitochondrial fission and reduced ROS production in cardiomyocytes. In addition, we found that inhibition of the MAPK/ERK pathway abolished the antioxidant action of Opa1-mediated mitophagy in these cells. Taken together, our data demonstrate that Opa1-mediated mitophagy protects cardiomyocytes against oxidative stress damage through inhibition of mitochondrial fission and activation of MAPK/ERK signaling. These findings reveal a critical role for Opa1 in the modulation of cardiomyocyte redox balance and suggest a potential target for the treatment of myocardial infarction.

DOI: https://doi.org/10.1155/2021/3726885
Mov Disord. 2021 Jul 01.

Disturbed Mitochondria-Lysosome Crosstalk in GBA1-Associated Parkinson's Disease.

Chi-Jing Choong, Yasuyoshi Kimura, Hideki Mochizuki.

DOI: https://doi.org/10.1002/mds.28693
Redox Biol. 2021 Jun 19. pii: S2213-2317(21)00211-1. [Epub ahead of print]45 102052

Acid ceramidase improves mitochondrial function and oxidative stress in Niemann-Pick type C disease by repressing STARD1 expression and mitochondrial cholesterol accumulation.

Sandra Torres, Estel Solsona-Vilarrasa, Susana Nuñez, Nuria Matías, Naroa Insausti-Urkia, Fernanda Castro, Mireia Casasempere, Gemma Fabriás, Josefina Casas, Carlos Enrich, José C Fernández-Checa, Carmen Garcia-Ruiz.

  Niemann-Pick type C (NPC) disease, a lysosomal storage disorder caused by defective NPC1/NPC2 function, results in the accumulation of cholesterol and glycosphingolipids in lysosomes of affected organs, such as liver and brain. Moreover, increase of mitochondrial cholesterol (mchol) content and impaired mitochondrial function and GSH depletion contribute to NPC disease. However, the underlying mechanism of mchol accumulation in NPC disease remains unknown. As STARD1 is crucial in intramitochondrial cholesterol trafficking and acid ceramidase (ACDase) has been shown to regulate STARD1, we explored the functional relationship between ACDase and STARD1 in NPC disease. Liver and brain of Npc1-/- mice presented a significant increase in mchol levels and STARD1 expression. U18666A, an amphiphilic sterol that inhibits lysosomal cholesterol efflux, increased mchol levels in hepatocytes from Stard1f/f mice but not Stard1ΔHep mice. We dissociate the induction of STARD1 expression from endoplasmic reticulum stress, and establish an inverse relationship between ACDase and STARD1 expression and LRH-1 levels. Hepatocytes from Npc1+/+ mice treated with U18666A exhibited increased mchol accumulation, STARD1 upregulation and decreased ACDase expression, effects that were reversed by cholesterol extraction with 2-hydroxypropyl-β-cyclodextrin. Moreover, transfection of fibroblasts from NPC patients with ACDase, decreased STARD1 expression and mchol accumulation, resulting in increased mitochondrial GSH levels, improved mitochondrial functional performance, decreased oxidative stress and protected NPC fibroblasts against oxidative stress-mediated cell death. Our results demonstrate a cholesterol-dependent inverse relationship between ACDase and STARD1 and provide a novel approach to target the accumulation of cholesterol in mitochondria in NPC disease.

Keywords:  Acid ceramiase; Cholesterol; Mitochondrial function; NPC disease; Oxidative stress

DOI:  https://doi.org/10.1016/j.redox.2021.102052
Am J Physiol Cell Physiol. 2021 06 30.

Dystrophin deficiency disrupts muscle clock expression and mitochondrial quality control in mdx mice.

Justin P Hardee, Marissa K Caldow, Audrey S M Chan, Stuart K Plenderleith, Jennifer Trieu, Rene Koopman, Gordon S Lynch.

  Impaired oxidative capacity and mitochondrial function contribute to the dystrophic pathology in muscles of Duchenne muscular dystrophy (DMD) patients and in relevant mouse models of the disease. Emerging evidence suggests an association between disrupted core clock expression and mitochondrial quality control, but this has not been established in muscles lacking dystrophin. We examined the diurnal regulation of muscle core clock and mitochondrial quality control expression in dystrophin-deficient C57BL/10ScSn-Dmdmdx (mdx) mice, an established model of DMD. Male C57BL/10 (BL/10; n=18) and mdx mice (n=18) were examined every 4 hours beginning at the dark cycle. Throughout the entire light-dark cycle, extensor digitorum longus (EDL) muscles from mdx mice had decreased core clock mRNA expression (Arntl, Cry1, Cry2, Nr1d2; p<0.05) and disrupted mitochondrial quality control mRNA expression related to biogenesis (decreased; Ppargc1a, Esrra; p<0.05), fission (increased; Dnm1l; p<0.01), fusion (decreased; Opa1, Mfn1; p<0.05) and autophagy/mitophagy (decreased: Bnip3; p<0.05; increased: Becn1; p<0.05). Cosinor analysis revealed a decrease in the rhythmicity parameters mesor and amplitude for Arntl, Cry1, Cry2, Per2, and Nr1d1 (p<0.001) in mdx mice. Diurnal oscillations in Esrra, Sirt1, Map1lc3b and Sqstm1 were absent in mdx mice, along with decreased mesor and amplitude of Ppargc1a mRNA expression (p<0.01). The expression of proteins involved in mitochondrial biogenesis (decreased: PPARGC1A, p<0.05) and autophagy/mitophagy (increased: MAP1LC3BII, SQSTM1, BNIP3; p<0.05) were also dysregulated in tibialis anterior muscles of mdx mice. These findings suggest that dystrophin deficiency in mdx mice impairs the regulation of the core clock and mitochondrial quality control, with relevance to DMD and related disorders.

Keywords:  diurnal variation; dystrophin; mitochondria; muscular dystrophy

DOI:  https://doi.org/10.1152/ajpcell.00188.2021
Int J Mol Sci. 2021 Jun 27. pii: 6897. [Epub ahead of print]22(13):

Amino Acid-Mediated Intracellular Ca2+ Rise Modulates mTORC1 by Regulating the TSC2-Rheb Axis through Ca2+/Calmodulin.

Yuna Amemiya, Nao Nakamura, Nao Ikeda, Risa Sugiyama, Chiaki Ishii, Masatoshi Maki, Hideki Shibata, Terunao Takahara.

  Mechanistic target of rapamycin complex 1 (mTORC1) is a master growth regulator by controlling protein synthesis and autophagy in response to environmental cues. Amino acids, especially leucine and arginine, are known to be important activators of mTORC1 and to promote lysosomal translocation of mTORC1, where mTORC1 is thought to make contact with its activator Rheb GTPase. Although amino acids are believed to exclusively regulate lysosomal translocation of mTORC1 by Rag GTPases, how amino acids increase mTORC1 activity besides regulation of mTORC1 subcellular localization remains largely unclear. Here we report that amino acids also converge on regulation of the TSC2-Rheb GTPase axis via Ca2+/calmodulin (CaM). We showed that the amino acid-mediated increase of intracellular Ca2+ is important for mTORC1 activation and thereby contributes to the promotion of nascent protein synthesis. We found that Ca2+/CaM interacted with TSC2 at its GTPase activating protein (GAP) domain and that a CaM inhibitor reduced binding of CaM with TSC2. The inhibitory effect of a CaM inhibitor on mTORC1 activity was prevented by loss of TSC2 or by an active mutant of Rheb GTPase, suggesting that a CaM inhibitor acts through the TSC2-Rheb axis to inhibit mTORC1 activity. Taken together, in response to amino acids, Ca2+/CaM-mediated regulation of the TSC2-Rheb axis contributes to proper mTORC1 activation, in addition to the well-known lysosomal translocation of mTORC1 by Rag GTPases.

Keywords:  Rheb GTPase; TSC; amino acid; calcium; calmodulin; mTOR

DOI:  https://doi.org/10.3390/ijms22136897
Ecotoxicol Environ Saf. 2021 Jun 26. pii: S0147-6513(21)00562-5. [Epub ahead of print]221 112450

Coenzyme Q10 ameliorates BPA-induced apoptosis by regulating autophagy-related lysosomal pathways.

Yuan Liu, Yaxin Yao, Wenjing Tao, Feng Liu, Songbai Yang, Ayong Zhao, Dan Song, Xiangchen Li.

  Bisphenol A (BPA) is a widely distributed environmental endocrine disruptor. The accumulation of BPA has been proved that produce various toxic effects both on human and animals. However, the strategies to reduce the damage of BPA on the body and related mechanisms remain to be studied. Coenzyme Q10 (CoQ10), as a powerful antioxidant, is ubiquitous in many eukaryotic cells, which can improve the integrity of lysosomal membrane, lysosomal degradation function and promote autophagy. Here, we examined the ability of CoQ10 to alleviate oxidative stress and apoptosis in BPA-induced damages in C2C12 cells, and how to alleviate it. Our results showed that BPA treatment significantly reduced cell viability, increased the number of cell apoptosis and ROS production, decreased mitochondrial membrane potential, and inhibited the gene expression of mitochondria biogenesis. Moreover, we demonstrated that exposure to BPA increased expression levels of autophagy protein (LC3-II, p62), inhibited autophagy flux, and disrupted the acidic pH environment of lysosomes. Importantly, CoQ10 supplementation effectively restored these abnormalities caused by BPA. CoQ10 significantly decreased the apoptotic incidence and ROS levels, improved mitochondrial membrane potential. Moreover, CoQ10 improved lysosome function and enhanced autophagy flux. Taken together, our results indicate that CoQ10 supplementation is a feasible and effective way to promote the level of autophagy by improving lysosomal function, thereby reducing the apoptosis caused by BPA accumulation. This study aims to provide evidence for the role of CoQ10 in repairing BPA-induced cell damage in clinical practice.

Keywords:  Apoptosis; Autophagy; Bisphenol A; Coenzyme Q10; Lysosome

DOI:  https://doi.org/10.1016/j.ecoenv.2021.112450
Pharmaceuticals (Basel). 2021 Jun 23. pii: 607. [Epub ahead of print]14(7):

Nrf2/ARE Activators Improve Memory in Aged Mice via Maintaining of Mitochondrial Quality Control of Brain and the Modulation of Gut Microbiome.

Irina S Sadovnikova, Artem P Gureev, Daria A Ignatyeva, Maria V Gryaznova, Ekaterina V Chernyshova, Ekaterina P Krutskikh, Anastasia G Novikova, Vasily N Popov.

  Aging is one of the most serious factors for central nervous dysfunctions, which lead to cognitive impairment. New highly effective drugs are required to slow the development of cognitive dysfunction. This research studied the effect of dimethyl fumarate (DMF), methylene blue (MB), and resveratrol (RSV) on the cognitive functions of 15-month-old mice and their relationship to the maintenance of mitochondrial quality control in the brain and the bacterial composition of the gut microbiome. We have shown that studied compounds enhance mitochondrial biogenesis, mitophagy, and antioxidant defense in the hippocampus of 15-month-old mice via Nrf2/ARE pathway activation, which reduces the degree of oxidative damage to mtDNA. It is manifested in the improvement of short-term and long-term memory. We have also shown that memory improvement correlates with levels of Roseburia, Oscillibacter, ChristensenellaceaeR-7, Negativibacillus, and Faecalibaculum genera of bacteria. At the same time, long-term treatment by MB induced a decrease in gut microbiome diversity, but the other markers of dysbiosis were not observed. Thus, Nrf2/ARE activators have an impact on mitochondrial quality control and are associated with a positive change in the composition of the gut microbiome, which together lead to an improvement in memory in aged mice.

Keywords:  Nrf2/ARE pathway; aging; antioxidants; cognitive dysfunction; dimethyl fumarate; gut microbiome; gut–brain axis; memory; methylene blue; mitochondrial biogenesis; mitophagy; resveratrol

DOI:  https://doi.org/10.3390/ph14070607
J Cell Mol Med. 2021 Jul 02.

The molecular mechanism underlying mitophagy-mediated hippocampal neuron apoptosis in diabetes-related depression.

Jian Liu, Lin Liu, Yuan-Shan Han, Jian Yi, Chun Guo, Hong-Qing Zhao, Jia Ling, Yu-Hong Wang.

  Diabetes-related depression (DD) is a major complication of diabetes mellitus. Our previous studies indicated that glutamate (Glu) and hippocampal neuron apoptosis are key signal and direct factor leading to diabetes-related depression, respectively. However, the accurate pathogenesis remains to be unclear. We hypothesized that diabetes-related depression might be associated with the mitophagy-mediated hippocampal neuron apoptosis, triggered by aberrant Glu-glutamate receptor2 (GluR2)-Parkin pathway. To testify this hypothesis, here the rat model of DD in vivo and in vitro were both established so as to uncover the potential mechanism of DD based on mitophagy and apoptosis. We found that DD rats exhibit an elevated glutamate levels followed by monoamine neurotransmitter deficiency and depressive-like behaviour, and DD modelling promoted autophagosome formation and caused mitochondrial impairment, eventually leading to hippocampal neuron apoptosis via aberrant Glu-GluR2-Parkin pathway. Further, in vitro study demonstrated that the simulated DD conditions resulted in an abnormal glutamate and monoamine neurotransmitter levels followed by autophagic flux increment, mitochondrial membrane potential reduction and mitochondrial reactive oxygen species and lactic dehydrogenase elevation. Interestingly, both GluR2 and mammalian target of rapamycin (mTOR) receptor blocker aggravated mitophagy-induced hippocampal neuron apoptosis and abnormal expression of apoptotic protein. In contrast, both GluR2 and mTOR receptor agonist ameliorated those apoptosis in simulated DD conditions. Our findings revealed that mitophagy-mediated hippocampal neuron apoptosis, triggered by aberrant Glu-GluR2-Parkin pathway, is responsible for depressive-like behaviour and monoamine neurotransmitter deficiency in DD rats. This work provides promising molecular targets and strategy for the treatment of DD.

Keywords:  Apoptosis; Diabetes-related depression; GluR2; Glutamate; Hippocampal neuron; Mitophagy; Parkin

DOI:  https://doi.org/10.1111/jcmm.16763