bims-mikwok 2021-03-21 papers

bims-mikwok

Biomed News

on Mitochondrial quality control

Issue of 2021–03–21
eleven papers selected by
Avinash N. Mukkala, University of Toronto

CREG1 improves the capacity of the skeletal muscle response to exercise endurance via modulation of mitophagy.
Autophagy facilitates mitochondrial rebuilding after acute heat stress via a DRP-1-dependent process.
Mitochondrial dynamics in health and disease.
The cyclophilin inhibitor NIM-811 increases muscle cell survival with hypoxia in vitro and improves gait performance following ischemia-reperfusion in vivo.
The lysosomal membrane protein Sidt2 is a vital regulator of mitochondrial quality control in skeletal muscle.
AMPK protects against alcohol-induced liver injury through UQCRC2 to up-regulate mitophagy.
NLRP3 Deficiency Protects Against Intermittent Hypoxia-Induced Neuroinflammation and Mitochondrial ROS by Promoting the PINK1-Parkin Pathway of Mitophagy in a Murine Model of Sleep Apnea.
Parkin is an E3 ligase for the ubiquitin-like modifier FAT10, which inhibits Parkin activation and mitophagy.
Real-Time Assessment of Mitochondrial Toxicity in HepG2 Cells Using the Seahorse Extracellular Flux Analyzer.
Mitochondrial transfer from MSCs to macrophages restricts inflammation and alleviates kidney injury in diabetic nephropathy mice via PGC-1α activation.
Mitochondria-rough-ER contacts in the liver regulate systemic lipid homeostasis.

Autophagy. 2021 Mar 17.

CREG1 improves the capacity of the skeletal muscle response to exercise endurance via modulation of mitophagy.

HaiXu Song, Xiaoxiang Tian, Dan Liu, Meili Liu, Yanxia Liu, Jing Liu, Zhu Mei, Chenghui Yan, Yaling Han.

  CREG1 (cellular repressor of E1A-stimulated genes 1) is involved in tissue homeostasis and influences macroautophagy/autophagy to protect cardiovascular function. However, the physiological and pathological role of CREG1 in the skeletal muscle is not clear. Here, we established a skeletal muscle-specific creg1 knockout mouse model (creg1;Ckm-Cre) by crossing the Creg1-floxed mice (Creg1fl/fl) with a transgenic line expressing Cre recombinase under the muscle-specific Ckm (creatine kinase, muscle) promoter. In creg1;Ckm-Cre mice, the exercise time to exhaustion and running distance were significantly reduced compared to Creg1fl/fl mice at the age of 9 months. In addition, the administration of recombinant (re)CREG1 protein improved the motor function of 9-month-old creg1;Ckm-Cre mice. Moreover, electron microscopy images of 9-month-old creg1;Ckm-Cre mice showed that the mitochondrial quality and quantity were abnormal and associated with increased levels of PINK1 (PTEN induced putative kinase 1) and PRKN/PARKIN (parkin RBR E3 ubiquitin protein ligase) but reduced levels of the mitochondrial proteins PTGS2/COX2, COX4I1/COX4, and TOMM20. These results suggested that CREG1 deficiency accelerated the induction of mitophagy in the skeletal muscle. Mechanistically, gain-and loss-of-function mutations of Creg1 altered mitochondrial morphology and function, impairing mitophagy in C2C12 cells. Furthermore, HSPD1/HSP60 (heat shock protein 1) (401-573 aa) interacted with CREG1 (130-220 aa) to antagonize the degradation of CREG1 and was involved in the regulation of mitophagy. To the best of our knowledge, this was the first time to demonstrate that CREG1 localized to the mitochondria and played an important role in mitophagy modulation that determined skeletal muscle wasting during the growth process or disease conditions.

Keywords:  CREG1; HSPD1; mitochondria; mitophagy; skeletal muscle

DOI:  https://doi.org/10.1080/15548627.2021.1904488
J Cell Biol. 2021 Apr 05. pii: e201909139. [Epub ahead of print]220(4):

Autophagy facilitates mitochondrial rebuilding after acute heat stress via a DRP-1-dependent process.

Yanfang Chen, Romane Leboutet, Céline Largeau, Siham Zentout, Christophe Lefebvre, Agnès Delahodde, Emmanuel Culetto, Renaud Legouis.

Acute heat stress (aHS) can induce strong developmental defects in Caenorhabditis elegans larva but not lethality or sterility. This stress results in transitory fragmentation of mitochondria, formation of aggregates in the matrix, and decrease of mitochondrial respiration. Moreover, active autophagic flux associated with mitophagy events enables the rebuilding of the mitochondrial network and developmental recovery, showing that the autophagic response is protective. This adaptation to aHS does not require Pink1/Parkin or the mitophagy receptors DCT-1/NIX and FUNDC1. We also find that mitochondria are a major site for autophagosome biogenesis in the epidermis in both standard and heat stress conditions. In addition, we report that the depletion of the dynamin-related protein 1 (DRP-1) affects autophagic processes and the adaptation to aHS. In drp-1 animals, the abnormal mitochondria tend to modify their shape upon aHS but are unable to achieve fragmentation. Autophagy is induced, but autophagosomes are abnormally elongated and clustered on mitochondria. Our data support a role for DRP-1 in coordinating mitochondrial fission and autophagosome biogenesis in stress conditions.

DOI: https://doi.org/10.1083/jcb.201909139
FEBS Lett. 2021 Mar 20.

Mitochondrial dynamics in health and disease.

Nethmi M B Yapa, Valerie Lisnyak, Boris Reljic, Michael T Ryan.

  In animals, mitochondria are mainly organised into an interconnected tubular network extending across the cell along a cytoskeletal scaffold. Mitochondrial fission and fusion, as well as distribution along cytoskeletal tracks, are counterbalancing mechanisms acting in concert to maintain a mitochondrial network tuned to cellular function. Balanced mitochondrial dynamics permits quality control of the network including biogenesis and turnover, distribution of mtDNA, and are tuned to metabolic status. Cellular and organismal health relies on a delicate balance between fission and fusion and large rearrangements in the mitochondrial network can be seen in response to cellular insults and disease. Indeed, dysfunction in the major components of the fission and fusion machineries including Dynamin-related protein 1 (DRP1), Mitofusins 1 and 2 (MFN1, MFN2) and Optic atrophy protein 1 (OPA1) and ensuing imbalance of mitochondrial dynamics can lead to neurodegenerative disease. Altered mitochondrial dynamics is also seen in more common diseases. In this review, the machinery involved in mitochondrial dynamics and their dysfunction in disease will be discussed.

Keywords:  membrane dynamics; mitochondria; mitochondrial disease; mitochondrial fission; mitochondrial fusion; organelles; oxidative phosphorylation

DOI:  https://doi.org/10.1002/1873-3468.14077
Sci Rep. 2021 Mar 17. 11(1): 6152

The cyclophilin inhibitor NIM-811 increases muscle cell survival with hypoxia in vitro and improves gait performance following ischemia-reperfusion in vivo.

Khairat Bahgat Youssef El Baradie, Mohammad B Khan, Bharati Mendhe, Jennifer Waller, Frederick O'Brien, Mark W Hamrick.

Acute ischemia-reperfusion injury in skeletal muscle is a significant clinical concern in the trauma setting. The mitochondrial permeability transition inhibitor NIM-811 has previously been shown to reduce ischemic injury in the liver and kidney. The effects of this treatment on skeletal muscle are, however, not well understood. We first used an in vitro model of muscle cell ischemia in which primary human skeletal myoblasts were exposed to hypoxic conditions (1% O2 and 5% CO2) for 6 h. Cells were treated with NIM-811 (0-20 µM). MTS assay was used to quantify cell survival and LDH assay to quantify cytotoxicity 2 h after treatment. Results indicate that NIM-811 treatment of ischemic myotubes significantly increased cell survival and decreased LDH in a dose-dependent manner. We then examined NIM-811 effects in vivo using orthodontic rubber bands (ORBs) for 90 min of single hindlimb ischemia. Mice received vehicle or NIM-811 (10 mg/kg BW) 10 min before reperfusion and 3 h later. Ischemia and reperfusion were monitored using laser speckle imaging. In vivo data demonstrate that mice treated with NIM-811 showed increased gait speed and improved Tarlov scores compared to vehicle-treated mice. The ischemic limbs of female mice treated with NIM-811 showed significantly lower levels of MCP-1, IL-23, IL-6, and IL-1α compared to limbs of vehicle-treated mice. Similarly, male mice treated with NIM-811 showed significantly lower levels of MCP-1 and IL-1a. These findings are clinically relevant as MCP-1, IL-23, IL-6, and IL-1α are all pro-inflammatory factors that are thought to contribute directly to tissue damage after ischemic injury. Results from the in vitro and in vivo experiments suggest that NIM-811 and possibly other mitochondrial permeability transition inhibitors may be effective for improving skeletal muscle salvage and survival after ischemia-reperfusion injury.

DOI: https://doi.org/10.1038/s41598-021-85753-x
FASEB J. 2021 Apr;35(4): e21223

The lysosomal membrane protein Sidt2 is a vital regulator of mitochondrial quality control in skeletal muscle.

Lizhuo Wang, Cui Yu, Wenjun Pei, Mengya Geng, Yao Zhang, Zihui Li, Feiteng Liang, Fengbiao Tan, Hui Du, Jialin Gao.

  The role of Sidt2 in the process of glucose and lipid metabolism has been recently reported. However, whether Sidt2 is involved in the metabolic regulation in skeletal muscle remains unknown. In this study, for the first time, using skeletal muscle-selective Sidt2 knockout mice, we found that Sidt2 was vital for the quality control of mitochondria in mouse skeletal muscle. These mice showed significantly reduced muscle tolerance and structurally abnormal mitochondria. Deletion of the Sidt2 gene resulted in decreased expression of mitochondrial fusion protein 2 (Mfn2) and Dynamin-related protein 1 (Drp1), as well as peroxisome proliferator-activated receptor γ coactivator-1 (PGC1-α). In addition, the clearance of damaged mitochondria in skeletal muscle was inhibited upon Sidt2 deletion, which was caused by blockade of autophagy flow. Mechanistically, the fusion of autophagosomes and lysosomes was compromised in Sidt2 knockout skeletal muscle cells. In summary, the deletion of the Sidt2 gene not only interfered with the quality control of mitochondria, but also inhibited the clearance of mitochondria and caused the accumulation of a large number of damaged mitochondria, ultimately leading to the abnormal structure and function of skeletal muscle.

Keywords:  Sidt2; autophagy; mitochondria; myopathy; quality control

DOI:  https://doi.org/10.1096/fj.202000424R
Autophagy. 2021 Mar 14. 1-22

AMPK protects against alcohol-induced liver injury through UQCRC2 to up-regulate mitophagy.

Xinyi Lu, Wenting Xuan, Juanjuan Li, Hongwei Yao, Cheng Huang, Jun Li.

  Recent reports indicated that mitophagy protects against alcohol-induced liver injury, which helps remove damaged mitochondria to reduce the accumulation of reactive oxygen species (ROS). AMP-activated protein kinase (AMPK) has been recently used in ALD (alcoholic liver disease) and mitochondrial dysfunction research. However, the inner mechanism, whether AMPK can regulate mitophagy in ALD, remains unknown. Here we found that AMPK can significantly reduce alcohol-induced liver injury and enhances hepatocytes' mitophagy level. Next, we identified that AMPK rescued alcohol-induced low expression of UQCRC2 (ubiquinol-cytochrome c reductase core protein 2). Interestingly, UQCRC2 knockdown (KD) treatment causes impaired mitophagy, whereas UQCRC2 overexpression (OE) can significantly increase mitophagy to attenuate liver injury. Also, we identified that AMPK indirectly upregulates UQCRC2 protein level, and RNA-seq, chromatin immunoprecipitation (ChIP) assay, bioinformatics, and luciferase assays helped us understand that AMPK enhanced UQCRC2 gene transcription through activating NFE2L2/NRF2 (nuclear factor, erythroid 2 like 2). Our results demonstrate that AMPK regulating UQCRC2 is a significant mitochondrial event in mitophagy. It identifies a new signaling axis, AMPK-NFE2L2-UQCRC2, in the regulation of mitophagy levels in the liver, suggesting a possible therapeutic strategy to treat ALD.Abbreviations: AAV: AENO-associated virus; ALD: alcoholic liver disease; AMPK: AMP-activated protein kinase; BUN: blood urea nitrogen; H&E: hematoxylin and eosin; CCCP: carbonyl cyanide 3-chlorophenylhydrazone; ChIP: chromatin immunoprecipitation assay; CO-IP: co-immunoprecipitation; COPD: chronic obstructive pulmonary disease; EM: electron microscope; GOT1/AST: glutamic-oxaloacetic transaminase 1; GPT/ALT: glutamic-pyruvic transaminase; IF: immunofluorescence; IHC: immunohistochemistry; KD: knockdown; MAP1LC3/LC3: microtubule associated protein 1 light chain protein 3; MTDR: MitoTracker Deep Red; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; mtDNA: mitochondrial DNA; MTRC: MitoTracker Red CMXRos; OCR: Oxygen consumption rate; OE: overexpress; PINK1: PTEN induced kinase 1; qRT-PCR: quantitative real-time PCR; ROS: reactive oxygen species; SD: standard deviation; SOD2: superoxide dismutase 2; UQCRC2: ubiquinol-cytochrome c reductase core protein 2; WB: western blot; ΔΨ: mitochondrial membrane potential.

Keywords:  AMPK; bioinformatics; mitophagy; rna-seq; transcription factor; uqcrc2

DOI:  https://doi.org/10.1080/15548627.2021.1886829
Front Immunol. 2021 ;12 628168

NLRP3 Deficiency Protects Against Intermittent Hypoxia-Induced Neuroinflammation and Mitochondrial ROS by Promoting the PINK1-Parkin Pathway of Mitophagy in a Murine Model of Sleep Apnea.

Xu Wu, Linjing Gong, Liang Xie, Wenyu Gu, Xinyuan Wang, Zilong Liu, Shanqun Li.

  Obstructive sleep apnea (OSA) associated neurocognitive impairment is mainly caused by chronic intermittent hypoxia (CIH)-triggered neuroinflammation and oxidative stress. Previous study has demonstrated that mitochondrial reactive oxygen species (mtROS) was pivotal for hypoxia-related tissue injury. As a cytosolic multiprotein complex that participates in various inflammatory and neurodegenerative diseases, NLRP3 inflammasome could be activated by mtROS and thereby affected by the mitochondria-selective autophagy. However, the role of NLRP3 and possible mitophagy mechanism in CIH-elicited neuroinflammation remain to be elucidated. Compared with wild-type mice, NLRP3 deficiency protected them from CIH-induced neuronal damage, as indicated by the restoration of fear-conditioning test results and amelioration of neuron apoptosis. In addition, NLRP3 knockout mice displayed the mitigated microglia activation that elicited by CIH, concomitantly with elimination of damaged mitochondria and reduction of oxidative stress levels (malondialdehyde and superoxide dismutase). Elevated LC3 and beclin1 expressions were remarkably observed in CIH group. In vitro experiments, intermittent hypoxia (IH) significantly facilitated mitophagy induction and NLRP3 inflammasome activation in microglial (BV2) cells. Moreover, IH enhanced the accumulation of damaged mitochondria, increased mitochondrial depolarization and augmented mtROS release. Consistently, NLRP3 deletion elicited a protective phenotype against IH through enhancement of Parkin-mediated mitophagy. Furthermore, Parkin deletion or pretreated with 3MA (autophagy inhibitor) exacerbated these detrimental actions of IH, which was accompanied with NLRP3 inflammasome activation. These results revealed NLRP3 deficiency acted as a protective promotor through enhancing Parkin-depended mitophagy in CIH-induced neuroinflammation. Thus, NLRP3 gene knockout or pharmacological blockage could be as a potential therapeutic strategy for OSA-associated neurocognitive impairment.

Keywords:  neuroinflammation; nucleotide‐binding domain like receptor protein 3 (NLRP3); obstructive sleep apnea (OSA); parkin-mediated mitophagy; reactive oxygen species (ROS)

DOI:  https://doi.org/10.3389/fimmu.2021.628168
Cell Rep. 2021 Mar 16. pii: S2211-1247(21)00171-6. [Epub ahead of print]34(11): 108857

Parkin is an E3 ligase for the ubiquitin-like modifier FAT10, which inhibits Parkin activation and mitophagy.

Nicola D Roverato, Carolin Sailer, Nicola Catone, Annette Aichem, Florian Stengel, Marcus Groettrup.

  Parkin is an E3 ubiquitin ligase belonging to the RING-between-RING family. Mutations in the Parkin-encoding gene PARK2 are associated with familial Parkinson's disease. Here, we investigate the interplay between Parkin and the inflammatory cytokine-induced ubiquitin-like modifier FAT10. FAT10 targets hundreds of proteins for degradation by the 26S proteasome. We show that FAT10 gets conjugated to Parkin and mediates its degradation in a proteasome-dependent manner. Parkin binds to the E2 enzyme of FAT10 (USE1), auto-FAT10ylates itself, and facilitates FAT10ylation of the Parkin substrate Mitofusin2 in vitro and in cells, thus identifying Parkin as a FAT10 E3 ligase. On mitochondrial depolarization, FAT10ylation of Parkin inhibits its activation and ubiquitin-ligase activity causing impairment of mitophagy progression and aggravation of rotenone-mediated death of dopaminergic neuronal cells. In conclusion, FAT10ylation inhibits Parkin and mitophagy rendering FAT10 a likely inflammation-induced exacerbating factor and potential drug target for Parkinson's disease.

Keywords:  FAT10; Parkin; Parkinson’s disease; mitophagy; ubiquitin-like modifier

DOI:  https://doi.org/10.1016/j.celrep.2021.108857
Curr Protoc. 2021 Mar;1(3): e75

Real-Time Assessment of Mitochondrial Toxicity in HepG2 Cells Using the Seahorse Extracellular Flux Analyzer.

Jether Amos Espinosa, Grace Pohan, Michelle R Arkin, Sarine Markossian.

  The liver is the primary organ responsible for drug detoxification. Drug-induced liver injury (DILI) is a leading cause of attrition during drug development and is one of the main reasons that drugs are withdrawn from the market. Hence, the prevention of DILI plays a central role in the overall drug-discovery process. Most of the liver's energy supply comes in the form of adenosine triphosphate (ATP), which is largely generated by mitochondria. This article describes the evaluation of drug-induced mitochondrial dysfunction using the Seahorse Extracellular Flux Analyzer (Agilent). The described protocols detail the accurate measurement of ATP production rate in HepG2 cells after exposure to a panel of potentially toxic compounds. This assay measures changes in extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) as indicators of glycolysis and mitochondrial respiration-the two major energy-generating pathways in a cell. This assay provides a useful model to predict mitochondrial dysfunction-mediated DILI. © 2021 Wiley Periodicals LLC. Basic Protocol: Measurement of cellular ECAR, OCR, and ATP production in live HepG2 cells Support Protocol 1: Culturing and maintaining of HepG2 cells Support Protocol 2: Determining optimal cell density per well.

Keywords:  ATP production; ECAR; HepG2; OCR; PER; Seahorse; drug-induced liver injury (DILI); glycolysis; mitochondrial respiration; oxidative phosphorylation

DOI:  https://doi.org/10.1002/cpz1.75
Stem Cells. 2021 Mar 19.

Mitochondrial transfer from MSCs to macrophages restricts inflammation and alleviates kidney injury in diabetic nephropathy mice via PGC-1α activation.

Yujia Yuan, Longhui Yuan, Lan Li, Fei Liu, Jingping Liu, Younan Chen, Jingqiu Cheng, Yanrong Lu.

  Mesenchymal stem cells (MSCs) have fueled ample translation for treatment of immune-mediated diseases. Our previous study had demonstrated that MSCs could elicit macrophages (Mϕ) into anti-inflammatory phenotypes, and alleviate kidney injury in diabetic nephropathy mice via improving mitochondrial function of Mϕ, yet the specific mechanism was unclear. Recent evidence indicated that MSCs communicated with their microenvironment through exchanges of mitochondria. By a co-culture system consisting of MSCs and Mϕ, we showed that MSCs-derived mitochondria (MSCs-Mito) were transferred into Mϕ, and the mitochondrial functions were improved, which contributed to M2 polarization. Furthermore, we found that MSCs-Mito transfer activated peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α)-mediated mitochondrial biogenesis. In addition, PGC-1α interacted with TFEB in high glucose (HG)-induced Mϕ, leading to the elevated lysosome-autophagy, which was essential to removal of damaged mitochondria. As a result, in Mϕ the mitochondrial bioenergy and capacity to combat inflammatory response were enhanced. Whereas, the immune-regulatory activity of MSCs-Mito was significantly blocked in PGC-1α knockdown Mϕ. More importantly, MSCs-Mito transfer could be observed in DN mice, and the adoptive transfer of MSCs-Mito educated Mϕ (MϕMito ) inhibited the inflammatory response and alleviated kidney injury. While the kidney-protective effects of MϕMito were abolished when the MSCs-Mito was impaired with rotenone (Rot), and the similar results were also observed when MϕMito were transfected with sipgc-1α before administration. Collectively, these findings suggested that MSCs elicited Mϕ into anti-inflammatory phenotype and ameliorated kidney injury through mitochondrial transfer in DN mice, and the effects were relied on PGC-1α-mediated mitochondrial biogenesis and PGC-1α/TFEB-mediated lysosome-autophagy. © AlphaMed Press 2021 SIGNIFICANCE STATEMENT: Our previous study had demonstrated that MSCs elicited Mϕ into M2 phenotype via improving mitochondrial function of Mϕ, yet the specific mechanism remained to be elucidated. The current study was the first to assess the potential role of mitochondrial transfer from MSCs to Mϕ and further explore the underlying mechanisms. We found that mitochondrial transfer from MSCs to Mϕ restricted inflammation and alleviated kidney injury in diabetic nephropathy mice via PGC-1α-mediated mitochondrial biogenesis and PGC-1α/TFEB-mediated autophagy. While shedding light on this new immune-regulatory mechanism, our findings offer strategies to improve cell-based therapies or eventual cell-free therapeutic approaches for inflammation-related diseases.

Keywords:  PGC-1α; TFEB; macrophages; mesenchymal stem cells; mitochondrial transfer

DOI:  https://doi.org/10.1002/stem.3375
Cell Rep. 2021 Mar 16. pii: S2211-1247(21)00187-X. [Epub ahead of print]34(11): 108873

Mitochondria-rough-ER contacts in the liver regulate systemic lipid homeostasis.

Irene Anastasia, Nicolò Ilacqua, Andrea Raimondi, Philippe Lemieux, Rana Ghandehari-Alavijeh, Guilhem Faure, Sergei L Mekhedov, Kevin J Williams, Federico Caicci, Giorgio Valle, Marta Giacomello, Ariel D Quiroga, Richard Lehner, Michael J Miksis, Katalin Toth, Thomas Q de Aguiar Vallim, Eugene V Koonin, Luca Scorrano, Luca Pellegrini.

  Contacts between organelles create microdomains that play major roles in regulating key intracellular activities and signaling pathways, but whether they also regulate systemic functions remains unknown. Here, we report the ultrastructural organization and dynamics of the inter-organellar contact established by sheets of curved rough endoplasmic reticulum closely wrapped around the mitochondria (wrappER). To elucidate the in vivo function of this contact, mouse liver fractions enriched in wrappER-associated mitochondria are analyzed by transcriptomics, proteomics, and lipidomics. The biochemical signature of the wrappER points to a role in the biogenesis of very-low-density lipoproteins (VLDL). Altering wrappER-mitochondria contacts curtails VLDL secretion and increases hepatic fatty acids, lipid droplets, and neutral lipid content. Conversely, acute liver-specific ablation of Mttp, the most upstream regulator of VLDL biogenesis, recapitulates this hepatic dyslipidemia phenotype and promotes remodeling of the wrappER-mitochondria contact. The discovery that liver wrappER-mitochondria contacts participate in VLDL biology suggests an involvement of inter-organelle contacts in systemic lipid homeostasis.

Keywords:  MAM; MUP; Rrbp1; VLDL; endoplasmic reticulum; inter-organelle contact; lipoprotein; liver metabolism; mitochondria; wrappER

DOI:  https://doi.org/10.1016/j.celrep.2021.108873