bims-tofagi 2023-10-08 papers

on Mitophagy

Issue of 2023–10–08
twelve papers selected by
Michele Frison, University of Cambridge and Aitor Martínez Zarate, Euskal Herriko Unibertsitatea

Mitophagy for cardioprotection.
Complementary Approaches to Interrogate Mitophagy Flux in Pancreatic β-Cells.
Liquid-liquid phase separation regulates alpha-synuclein aggregate and mitophagy in Parkinson's disease.
Zika virus modulates mitochondrial dynamics, mitophagy, and mitochondria-derived vesicles to facilitate viral replication in trophoblast cells.
Active fraction of Polyrhachis vicina (Roger) alleviated cerebral ischemia/reperfusion injury by targeting SIRT3-mediated mitophagy and angiogenesis.
PINK1-mediated mitophagy induction protects against preeclampsia by decreasing ROS and trophoblast pyroptosis.
Targeting Syntaxin 17 to Improve Mitophagy in Heart Failure.
Syntaxin 17 Protects Against Heart Failure Through Recruitment of CDK1 to Promote DRP1-Dependent Mitophagy.
Pgam5-mediated PHB2 dephosphorylation contributes to endotoxemia-induced myocardial dysfunction by inhibiting mitophagy and the mitochondrial unfolded protein response.
Src inhibition rescues FUNDC1-mediated neuronal mitophagy in ischaemic stroke.
Crotonylated BEX2 interacts with NDP52 and enhances mitophagy to modulate chemotherapeutic agent-induced apoptosis in non-small-cell lung cancer cells.
Mitochondrial Targeted Interventions for Aging.

Basic Res Cardiol. 2023 Oct 05. 118(1): 42

Mitophagy for cardioprotection.

Allen Sam Titus, Eun-Ah Sung, Daniela Zablocki, Junichi Sadoshima.

  Mitochondrial function is maintained by several strictly coordinated mechanisms, collectively termed mitochondrial quality control mechanisms, including fusion and fission, degradation, and biogenesis. As the primary source of energy in cardiomyocytes, mitochondria are the central organelle for maintaining cardiac function. Since adult cardiomyocytes in humans rarely divide, the number of dysfunctional mitochondria cannot easily be diluted through cell division. Thus, efficient degradation of dysfunctional mitochondria is crucial to maintaining cellular function. Mitophagy, a mitochondria specific form of autophagy, is a major mechanism by which damaged or unnecessary mitochondria are targeted and eliminated. Mitophagy is active in cardiomyocytes at baseline and in response to stress, and plays an essential role in maintaining the quality of mitochondria in cardiomyocytes. Mitophagy is mediated through multiple mechanisms in the heart, and each of these mechanisms can partially compensate for the loss of another mechanism. However, insufficient levels of mitophagy eventually lead to mitochondrial dysfunction and the development of heart failure. In this review, we discuss the molecular mechanisms of mitophagy in the heart and the role of mitophagy in cardiac pathophysiology, with the focus on recent findings in the field.

Keywords:  Alternative mitophagy; Drp1; Mitochondrial quality control; Mitophagy

DOI:  https://doi.org/10.1007/s00395-023-01009-x
J Vis Exp. 2023 09 15.

Complementary Approaches to Interrogate Mitophagy Flux in Pancreatic β-Cells.

Elena Levi-D'Ancona, Vaibhav Sidarala, Scott A Soleimanpour.

Mitophagy is a quality control mechanism necessary to maintain optimal mitochondrial function. Dysfunctional β-cell mitophagy results in insufficient insulin release. Advanced quantitative assessments of mitophagy often require the use of genetic reporters. The mt-Keima mouse model, which expresses a mitochondria-targeted pH-sensitive dual-excitation ratiometric probe for quantifying mitophagy via flow cytometry, has been optimized in β-cells. The ratio of acidic-to-neutral mt-Keima wavelength emissions can be used to robustly quantify mitophagy. However, using genetic mitophagy reporters can be challenging when working with complex genetic mouse models or difficult-to-transfect cells, such as primary human islets. This protocol describes a novel complementary dye-based method to quantify β-cell mitophagy in primary islets using MtPhagy. MtPhagy is a pH-sensitive, cell-permeable dye that accumulates in the mitochondria and increases its fluorescence intensity when mitochondria are in low pH environments, such as lysosomes during mitophagy. By combining the MtPhagy dye with Fluozin-3-AM, a Zn2+ indicator that selects for β-cells, and Tetramethylrhodamine, ethyl ester (TMRE) to assess mitochondrial membrane potential, mitophagy flux can be quantified specifically in β-cells via flow cytometry. These two approaches are highly complementary, allowing for flexibility and precision in assessing mitochondrial quality control in numerous β-cell models.

DOI: https://doi.org/10.3791/65789
Front Neurosci. 2023 ;17 1250532

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

Kaiying Hou, Tingting Liu, Jingwen Li, Meiyan Xian, Lin Sun, Jianshe Wei.

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

Keywords:  PINK1-Parkin; Parkinson’s disease; alpha-synuclein; liquid-liquid phase separation; mitophagy

DOI:  https://doi.org/10.3389/fnins.2023.1250532
Front Immunol. 2023 ;14 1203645

Zika virus modulates mitochondrial dynamics, mitophagy, and mitochondria-derived vesicles to facilitate viral replication in trophoblast cells.

Jae Kyung Lee, Ok Sarah Shin.

  Zika virus (ZIKV) remains a global public health threat with the potential risk of a future outbreak. Since viral infections are known to exploit mitochondria-mediated cellular processes, we investigated the effects of ZIKV infection in trophoblast cells in terms of the different mitochondrial quality control pathways that govern mitochondrial integrity and function. Here we demonstrate that ZIKV (PRVABC59) infection of JEG-3 trophoblast cells manipulates mitochondrial dynamics, mitophagy, and formation of mitochondria-derived vesicles (MDVs). Specifically, ZIKV nonstructural protein 4A (NS4A) translocates to the mitochondria, triggers mitochondrial fission and mitophagy, and suppresses mitochondrial associated antiviral protein (MAVS)-mediated type I interferon (IFN) response. Furthermore, proteomics profiling of small extracellular vesicles (sEVs) revealed an enrichment of mitochondrial proteins in sEVs secreted by ZIKV-infected JEG-3 cells, suggesting that MDV formation may also be another mitochondrial quality control mechanism manipulated during placental ZIKV infection. Altogether, our findings highlight the different mitochondrial quality control mechanisms manipulated by ZIKV during infection of placental cells as host immune evasion mechanisms utilized by ZIKV at the placenta to suppress the host antiviral response and facilitate viral infection.

Keywords:  mitochondria-derived vesicles (MDVs); mitochondrial quality control; mitophagy; nonstructural protein 4A (NS4A); zika virus (ZIKV)

DOI:  https://doi.org/10.3389/fimmu.2023.1203645
Phytomedicine. 2023 Sep 18. pii: S0944-7113(23)00464-6. [Epub ahead of print]121 155104

Active fraction of Polyrhachis vicina (Roger) alleviated cerebral ischemia/reperfusion injury by targeting SIRT3-mediated mitophagy and angiogenesis.

Jie Wei, Jiaxiu Xie, Junhui He, Dongmei Li, Dongmei Wei, Yi Li, Xiang Li, Weirong Fang, Guining Wei, Kedao Lai.

   BACKGROUND: Damaged mitophagy and impaired angiogenesis involve in the pathogenic development of ischemic stroke. Active fraction of Polyrhachis vicina (Roger) (AFPR) showed great potential on neurological disease with it's remarkable anti-inflammatory and anti-oxidative effects.
PURPOSE: This study designed to clarify the correlation between Pink1/Parkin-mediated mitophagy and angiogenesis after stroke, and to elucidate the role of SIRT3 in regulating mitophagy and angiogenesis, and to address the mechanism of AFPR on promoting mitophagy and angiogenesis in microvessels endothelium of ischemic brain.
STUDY DESIGN: A cerebral ischemia/reperfusion (CIR) rat model was developed by middle cerebral artery occlusion procedure. bEnd.3 cells were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to mimic CIR process. Neurological function, mitophagy and angiogenesis related indicators were measured. SIRT3 siRNA and 3-MA were used to verify the interaction between SIRT3-mediated mitophagy and angiogenesis.
METHODS: CIR rats were orally treated with AFPR (8 and 4 g raw drug /kg) and Nimodipine (10.8 mg/kg) for 12 days to mimic the recovery phase post-stroke. The neurological function assessment, TTC staining, HE staining, TUNEL staining and Nissl staining were performed to assess neuroprotective effects of AFPR against CIR. Then CD31-labeled microvessel density in brain was visualized and quantified by immunofluorescence staining. Mitochondrial ultrastructure was assessed by transmission electron microscope scanning. Expressions of relative proteins,e.g. SIRT3, Pink1, Parkin, LC3-II, p62, VEGFA, involving in mitophagy and angiogenesis, were detected by Western blotting analysis. In vitro, bEnd.3 cells were cultured with AFPR or in combination of autophagy inhibitor 3-MA during the reoxygenation. Then cell viability, and LDH releasing were measured. Angiogenic indicators,such as migration and tube formation activity, VEGFA level were determined. To assess effects of AFPR on mitophagy, mitophagy-related proteins were detected, as well as the autophagosome engulfment and lysosome degradation of mitochondria. To address the role of SIRT3, deacetylation activity of SIRT3 was validated by detecting acetylated FOXO3A level with co-immunoprecipitation (Co-IP) assay. Pre-treatment of siRNA or combination use of 3-MA were used to verify the detailed mechanism.
RESULTS: AFPR remarkably reduced neurological scores and infarct size, alleviated neuron apoptosis in cortex, and increased Nissl density in hippocampus of CIR rats. In addition, AFPR significantly promoted angiogenesis by increasing microvessels density and VEGFA expressions, increased SIRT3 expression, and activated Pink1/Parkin mediated mitophagy. In bEnd.3 cells, the combination use of 3-MA and AFPR further demonstrated that AFPR might promote angiogenesis after OGD/R injury through activating Pink1/Parkin mediated mitophagy. Co-IP assay suggested AFPR reduced acetylated FOXO3A level. This might be correlated with an elevation of SIRT3 expression and it's deacetylation activity. SIRT3 siRNA pretreatment significantly abolished the activation of mitophagy through Pink1/Parkin axis, eventually inhibited angiogenesis.
CONCLUSION: AFPR promoted angiogenesis through activating mitophagy after cerebral ischemia reperfusion, which might partially involved in the amelioration of SIRT3-mediated regulation on Pink1/Parkin axis. Our study will shed new light on the role of SIRT3 in ischemic brain, especially in regulating mitophagy and angiogenesis after stroke.

Keywords:  Angiogenesis; Central nervous system; Cerebral ischemia/reperfusion; Mitophagy; Sirtuin 3; Stroke

DOI:  https://doi.org/10.1016/j.phymed.2023.155104
Placenta. 2023 Sep 27. pii: S0143-4004(23)00565-9. [Epub ahead of print]143 1-11

PINK1-mediated mitophagy induction protects against preeclampsia by decreasing ROS and trophoblast pyroptosis.

Yanan Sun, Dan Lv, Yin Xie, Heze Xu, Xuanxuan Li, Fanfan Li, Yao Fan, Xiaolei Zhang, Yanling Zhang, Suhua Chen, Mengzhou He, Dongrui Deng.

   INTRODUCTION: Preeclampsia (PE) is a multisystemic disorder attributed to the excessive presentation of placenta-derived immunoinflammatory factors. PTEN-induced putative kinase 1 (PINK1)-mediated mitophagy participates in the development and persistence of the inflammation. We hypothesized that dysregulated mitophagy might be involved in the pathogenesis of PE by promoting the activation of trophoblast pyroptosis that augment inflammation.
METHODS: The morphology of mitochondrial in placenta were observed by transmission electron microscopy. The localization of PINK1 in the placenta was determined by immunohistochemistry. The expression levels of PINK1, PARKIN, LC3B, and SQSTM1 and pyroptosis-related molecules were compared between normal pregnancies and PE. We used hypoxia/reoxygenation (H/R) to stimulate the trophoblast hypoxia environment. HTR-8/SVneo cells were transfected with PINK1 plasmid and si-PINK1, respectively, and then were treated with H/R, to determine whether PINK1 regulated ROS and HTR-8/Svneo pyroptosis. Finally, ROS production was inhibited by MitoTEMPO to observe whether the pro-pyroptosis effect of PINK1 knockdown is alleviated.
RESULTS: Swollen mitochondrial were accumulated in the PE placentae. PINK1 is localized on villus trophoblast (VTs) and extravillous trophoblast (EVTs). PINK1-mediated mitophagy was abolished in the PE placenta, while the levels of pyroptosis were induced. H/R stimulation aggravated the downregulation of mitophagy and the up-regulation of pyroptosis. Overexpression of PINK1 mitigated H/R-induced upregulation of ROS and pyroptosis while silencing PINK1 did the opposite. Reducing ROS production can effectively resist the pro-pyroptosis effect of PINK1 knockdown.
DISCUSSION: This study demonstrated that PINK1-mediated mitophagy might played a protective role in PE by reducing ROS and trophoblast pyroptosis.

Keywords:  Mitophagy; PINK1; Preeclampsia; Pyroptosis; ROS

DOI:  https://doi.org/10.1016/j.placenta.2023.09.010
JACC Basic Transl Sci. 2023 Sep;8(9): 1240-1242

Targeting Syntaxin 17 to Improve Mitophagy in Heart Failure.

Maurizio Forte, Gianmarco Sarto, Sebastiano Sciarretta.



Keywords:  CDK1; MAMs; STX17; mitophagy; pressure overload-induced heart failure

DOI:  https://doi.org/10.1016/j.jacbts.2023.06.009
JACC Basic Transl Sci. 2023 Sep;8(9): 1215-1239

Syntaxin 17 Protects Against Heart Failure Through Recruitment of CDK1 to Promote DRP1-Dependent Mitophagy.

Haixia Xu, Xiang Wang, Wenjun Yu, Shiqun Sun, Ne N Wu, Junbo Ge, Jun Ren, Yingmei Zhang.

  Mitochondrial dysfunction is suggested to be a major contributor for the progression of heart failure (HF). Here we examined the role of syntaxin 17 (STX17) in the progression of HF. Cardiac-specific Stx17 knockout manifested cardiac dysfunction and mitochondrial damage, associated with reduced levels of p(S616)-dynamin-related protein 1 (DRP1) in mitochondria-associated endoplasmic reticulum membranes and dampened mitophagy. Cardiac STX17 overexpression promoted DRP1-dependent mitophagy and attenuated transverse aortic constriction-induced contractile and mitochondrial damage. Furthermore, STX17 recruited cyclin-dependent kinase-1 through its SNARE domain onto mitochondria-associated endoplasmic reticulum membranes, to phosphorylate DRP1 at Ser616 and promote DRP1-mediated mitophagy upon transverse aortic constriction stress. These findings indicate the potential therapeutic benefit of targeting STX17 in the mitigation of HF.

Keywords:  CDK1; DRP1; MAMs; STX17; mitophagy; pressure overload–induced heart failure

DOI:  https://doi.org/10.1016/j.jacbts.2023.04.006
Int J Biol Sci. 2023 ;19(14): 4657-4671

Pgam5-mediated PHB2 dephosphorylation contributes to endotoxemia-induced myocardial dysfunction by inhibiting mitophagy and the mitochondrial unfolded protein response.

Chen Cai, Ziying Li, Zemao Zheng, Zhongzhou Guo, Qian Li, Shuxian Deng, Nengxian Shi, Qing Ou, Hao Zhou, Zhigang Guo, Zhongqing Chen, Hang Zhu.

  Numerous mitochondrial abnormalities are reported to result from excessive inflammation during endotoxemia. Prohibitin 2 (PHB2) and phosphoglycerate mutase 5 (Pgam5) have been associated with altered mitochondrial homeostasis in several cardiovascular diseases; however, their role in endotoxemia-related myocardial dysfunction has not been explored. Our experiments were aimed to evaluate the potential contribution of Pgam5 and PHB2 to endotoxemia-induced mitochondrial dysfunction in cardiomyocytes, with a focus on two endogenous protective programs that sustain mitochondrial integrity, namely mitophagy and the mitochondrial unfolded protein response (UPRmt). We found that PHB2 transgenic mice are resistant to endotoxemia-mediated myocardial depression and mitochondrial damage. Our assays indicated that PHB2 overexpression activates mitophagy and the UPRmt, which maintains mitochondrial metabolism, prevents oxidative stress injury, and enhances cardiomyocyte viability. Molecular analyses further showed that Pgam5 binds to and dephosphorylates PHB2, resulting in cytosolic translocation of mitochondrial PHB2. Silencing of Pgam5 or transfection of a phosphorylated PHB2 mutant in mouse HL-1 cardiomyocytes prevented the loss of mitochondrially-localized PHB2 and activated mitophagy and UPRmt in the presence of LPS. Notably, cardiomyocyte-specific deletion of Pgam5 in vivo attenuated LPS-mediated myocardial dysfunction and preserved cardiomyocyte viability. These findings suggest that Pgam5/PHB2 signaling and mitophagy/UPRmt are potential targets for the treatment of endotoxemia-related cardiac dysfunction.

Keywords:  PHB2; Pgam5; endotoxemia-related cardiac dysfunction

DOI:  https://doi.org/10.7150/ijbs.85767
Stroke Vasc Neurol. 2023 Oct 04. pii: svn-2023-002606. [Epub ahead of print]

Src inhibition rescues FUNDC1-mediated neuronal mitophagy in ischaemic stroke.

Tianchi Tang, Li-Bin Hu, Chao Ding, Zhihua Zhang, Ning Wang, Tingting Wang, Hang Zhou, Siqi Xia, Linfeng Fan, Xiong-Jie Fu, Feng Yan, Xiangnan Zhang, Gao Chen, Jianru Li.

   BACKGROUND: Ischaemic stroke triggers neuronal mitophagy, while the involvement of mitophagy receptors in ischaemia/reperfusion (I/R) injury-induced neuronal mitophagy remain not fully elucidated. Here, we aimed to investigate the involvement of mitophagy receptor FUN14 domain-containing 1 (FUNDC1) and its modulation in neuronal mitophagy induced by I/R injury.
METHODS: Wild-type and FUNDC1 knockout mice were generated to establish models of neuronal I/R injury, including transient middle cerebral artery occlusion (tMCAO) in vivo and oxygen glucose deprivation/reperfusion in vitro. Stroke outcomes of mice with two genotypes were assessed. Neuronal mitophagy was analysed both in vivo and in vitro. Activities of FUNDC1 and its regulator Src were evaluated. The impact of Src on FUNDC1-mediated mitophagy was assessed through administration of Src antagonist PP1.
RESULTS: To our surprise, FUNDC1 knockout mice subjected to tMCAO showed stroke outcomes comparable to those of their wild-type littermates. Although neuronal mitophagy could be activated by I/R injury, FUNDC1 deletion did not disrupt neuronal mitophagy. Transient activation of FUNDC1, represented by dephosphorylation of Tyr18, was detected in the early stages (within 3 hours) of neuronal I/R injury; however, phosphorylated Tyr18 reappeared and even surpassed baseline levels in later stages (after 6 hours), accompanied by a decrease in FUNDC1-light chain 3 interactions. Spontaneous inactivation of FUNDC1 was associated with Src activation, represented by phosphorylation of Tyr416, which changed in parallel with the level of phosphorylated FUNDC1 (Tyr18) during neuronal I/R injury. Finally, FUNDC1-mediated mitophagy in neurons under I/R conditions can be rescued by pharmacological inhibition of Src.
CONCLUSIONS: FUNDC1 is inactivated by Src during the later stage (after 6 hours) of neuronal I/R injury, and rescue of FUNDC1-mediated mitophagy may serve as a potential therapeutic strategy for treating ischaemic stroke.

Keywords:  Stroke

DOI:  https://doi.org/10.1136/svn-2023-002606
Cell Death Dis. 2023 09 30. 14(9): 645

Crotonylated BEX2 interacts with NDP52 and enhances mitophagy to modulate chemotherapeutic agent-induced apoptosis in non-small-cell lung cancer cells.

Ning Mu, Yu Wang, Xiaopeng Li, Zhiyuan Du, Yingdi Wu, Min Su, Yingying Wang, Xiaoyang Sun, Ling Su, Xiangguo Liu.

Brain expressed X-linked gene 2 (BEX2) encoded protein was originally identified to promote transcription by interacting with several transcription factors in the DNA-binding complexes. Recently, BEX2 was found to be localized in cytosol and/or mitochondria and regulate apoptosis in cancer cells and tumor growth. However, the molecular mechanism underlying its roles in cancer cells remains unclear. Here, we report that crotonylated BEX2 plays an important role in inhibiting chemotherapeutic agent-induced apoptosis via enhancing mitophagy in human lung cancer cells. BEX2 promotes mitophagy by facilitating interaction between NDP52 and LC3B. Moreover, BEX2 crotonylation at K59 is critical in the BEX2-mediated mitophagy in lung cancer cells. The K59R mutation of BEX2 inhibits mitophagy by affecting the interaction of NDP52 and LC3B. BEX2 expression is elevated after anticancer drug treatment, and its overexpression inhibits chemotherapy-induced apoptosis. In addition, inhibition of BEX2-regulated mitophagy sensitizes tumor cells to apoptosis. Furthermore, BEX2 promotes tumor growth and inhibits apoptosis by regulating mitophagy in vivo. We also confirm that BEX2 is overexpressed in lung adenocarcinoma and is associated with poor prognosis in lymph node metastasis-free cancer. Therefore, combination treatment with pharmaceutical approaches targeting BEX2-induced mitophagy and anticancer drugs may represent a potential strategy for NSCLC therapy.

DOI: https://doi.org/10.1038/s41419-023-06164-6
Cold Spring Harb Perspect Med. 2023 Oct 03. pii: a041199. [Epub ahead of print]

Mitochondrial Targeted Interventions for Aging.

Sophia Z Liu, Ying Ann Chiao, Peter S Rabinovitch, David J Marcinek.

Changes in mitochondrial function play a critical role in the basic biology of aging and age-related disease. Mitochondria are typically thought of in the context of ATP production and oxidant production. However, it is clear that the mitochondria sit at a nexus of cell signaling where they affect metabolite, redox, and energy status, which influence many factors that contribute to the biology of aging, including stress responses, proteostasis, epigenetics, and inflammation. This has led to growing interest in identifying mitochondrial targeted interventions to delay or reverse age-related decline in function and promote healthy aging. In this review, we discuss the diverse roles of mitochondria in the cell. We then highlight some of the most promising strategies and compounds to target aging mitochondria in preclinical testing. Finally, we review the strategies and compounds that have advanced to clinical trials to test their ability to improve health in older adults.

DOI: https://doi.org/10.1101/cshperspect.a041199