bims-nenemi Biomed News
on Neuroinflammation, neurodegeneration and mitochondria
Issue of 2024–06–09
twelve papers selected by
Marco Tigano, Thomas Jefferson University
  1. Lipid unsaturation promotes BAX and BAK pore activity during apoptosis.
  2. Cytosolic Escape of Mitochondrial DNA Triggers cGAS-STING Pathway-Dependent Neuronal PANoptosis in Response to Intermittent Hypoxia.
  3. Mitochondrial DNA drives neuroinflammation through the cGAS-IFN signaling pathway in the spinal cord of neuropathic pain mice.
  4. Reduced Protein Import via TIM23 SORT Drives Disease Pathology in TIMM50-Associated Mitochondrial Disease.
  5. Structural basis for human mitochondrial tRNA maturation.
  6. A novel senolytic drug for pulmonary fibrosis: BTSA1 targets apoptosis of senescent myofibroblasts by activating BAX.
  7. Senescent-like microglia limit remyelination through the senescence associated secretory phenotype.
  8. Senescent glia link mitochondrial dysfunction and lipid accumulation.
  9. Lighting Up Nucleolus To Report Mitochondria Damage Using a Mitochondria-to-Nucleolus Migration Probe.
  10. Apoptosis signal-regulating kinase 1 promotes inflammation in senescence and aging.
  11. Mitophagy in relation to chronic inflammation/ROS in aging.
  12. Cardiolipin clustering promotes mitochondrial membrane dynamics.
  1. Nat Commun. 2024 Jun 03. 15(1): 4700
    Lipid unsaturation promotes BAX and BAK pore activity during apoptosis.
    Shashank Dadsena, Rodrigo Cuevas Arenas, Gonçalo Vieira, Susanne Brodesser, Manuel N Melo, Ana J García-Sáez.
      BAX and BAK are proapoptotic members of the BCL2 family that directly mediate mitochondrial outer membrane permeabilition (MOMP), a central step in apoptosis execution. However, the molecular architecture of the mitochondrial apoptotic pore remains a key open question and especially little is known about the contribution of lipids to MOMP. By performing a comparative lipidomics analysis of the proximal membrane environment of BAK isolated in lipid nanodiscs, we find a significant enrichment of unsaturated species nearby BAK and BAX in apoptotic conditions. We then demonstrate that unsaturated lipids promote BAX pore activity in model membranes, isolated mitochondria and cellular systems, which is further supported by molecular dynamics simulations. Accordingly, the fatty acid desaturase FADS2 not only enhances apoptosis sensitivity, but also the activation of the cGAS/STING pathway downstream mtDNA release. The correlation of FADS2 levels with the sensitization to apoptosis of different lung and kidney cancer cell lines by co-treatment with unsaturated fatty acids supports the relevance of our findings. Altogether, our work provides an insight on how local lipid environment affects BAX and BAK function during apoptosis.
    DOI:  https://doi.org/10.1038/s41467-024-49067-6
  2. Neurochem Res. 2024 Jun 04.
    Cytosolic Escape of Mitochondrial DNA Triggers cGAS-STING Pathway-Dependent Neuronal PANoptosis in Response to Intermittent Hypoxia.
    Shuying Wang, Jin Tan, Qiang Zhang.
      Intermittent hypoxia (IH) is the predominant pathophysiological disturbance in obstructive sleep apnea (OSA), characterized by neuronal cell death and neurocognitive impairment. We focus on the accumulated mitochondrial DNA (mtDNA) in the cytosol, which acts as a damage-associated molecular pattern (DAMP) and activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, a known trigger for immune responses and neuronal death in degenerative diseases. However, the specific role and mechanism of the mtDNA-cGAS-STING axis in IH-induced neural damage remain largely unexplored. Here, we investigated the involvement of PANoptosis, a novel type of programmed cell death linked to cytosolic mtDNA accumulation and the cGAS-STING pathway activation, in neuronal cell death induced by IH. Our study found that PANoptosis occurred in primary cultures of hippocampal neurons and HT22 cell lines exposed to IH. In addition, we discovered that during IH, mtDNA released into the cytoplasm via the mitochondrial permeability transition pore (mPTP) activates the cGAS-STING pathway, exacerbating PANoptosis-associated neuronal death. Pharmacologically inhibiting mPTP opening or depleting mtDNA significantly reduced cGAS-STING pathway activation and PANoptosis in HT22 cells under IH. Moreover, our findings indicated that the cGAS-STING pathway primarily promotes PANoptosis by modulating endoplasmic reticulum (ER) stress. Inhibiting or silencing the cGAS-STING pathway substantially reduced ER stress-mediated neuronal death and PANoptosis, while lentivirus-mediated STING overexpression exacerbated these effects. In summary, our study elucidates that cytosolic escape of mtDNA triggers cGAS-STING pathway-dependent neuronal PANoptosis in response to IH, mainly through regulating ER stress. The discovery of the novel mechanism provides theoretical support for the prevention and treatment of neuronal damage and cognitive impairment in patients with OSA.
    Keywords:  ER stress; Intermittent hypoxia; Obstructive sleep apnea; PANoptosis; STING; cGAS; mtDNA
    DOI:  https://doi.org/10.1007/s11064-024-04151-7
  3. Open Life Sci. 2024 ;19(1): 20220872
    Mitochondrial DNA drives neuroinflammation through the cGAS-IFN signaling pathway in the spinal cord of neuropathic pain mice.
    Penghui Huang, Li Li, Yaohua Chen, Yuping Li, Dan Zhu, Jian Cui.
      Neuroinflammation is pivotal in the development of neuropathic pain (NeP). While mitochondrial deoxyribonucleic acid (mtDNA) and cyclic GMP-AMP synthase (cGAS) are recognized for inducing inflammation in various neurological disorders, their involvement in NeP remains ambiguous. In this study, we examined: (1) the changes in mtDNA and cGAS in mice with NeP induced by chronic constriction injury (CCI) of the sciatic nerve, whether mtDNA triggers inflammation via the cGAS signaling; (2) the effects of RU.521, a cGAS antagonist, on CCI-induced nociception (allodynia and hyperalgesia) and relative inflammatory protein expression; (3) the activation of microglia and the cGAS-IFN pathway mediated by mtDNA in BV2 cell; (4) the effect of RU.521 on mtDNA-induced inflammatory response in BV2 cells. Results revealed reduced mtDNA levels in the sciatic nerve but increased levels in the spinal cord of CCI mice, along with elevated cGAS expression and inflammatory factors. RU.521 alleviated nociceptive behaviors in CCI mice, possibly by normalizing cGAS levels and suppressing inflammation. Neuron-derived mtDNA provoked cellular activation and upregulated cGAS signaling in BV2 cells. Additionally, RU.521 and DNase I effectively inhibited cGAS-induced inflammation. These findings underscore the critical role of mtDNA accumulation and mtDNA-mediated cGAS signaling in NeP development after peripheral nerve injury.
    Keywords:  microglia; mitochondrial deoxyribonucleic acid; neuroinflammation; neuropathic pain
    DOI:  https://doi.org/10.1515/biol-2022-0872
  4. Mol Cell Biol. 2024 Jun 03. 1-19
    Reduced Protein Import via TIM23 SORT Drives Disease Pathology in TIMM50-Associated Mitochondrial Disease.
    Jordan J Crameri, Catherine S Palmer, Tegan Stait, Thomas D Jackson, Matthew Lynch, Adriane Sinclair, Leah E Frajman, Alison G Compton, David Coman, David R Thorburn, Ann E Frazier, Diana Stojanovski.
      TIMM50 is a core subunit of the TIM23 complex, the mitochondrial inner membrane translocase responsible for the import of pre-sequence-containing precursors into the mitochondrial matrix and inner membrane. Here we describe a mitochondrial disease patient who is homozygous for a novel variant in TIMM50 and establish the first proteomic map of mitochondrial disease associated with TIMM50 dysfunction. We demonstrate that TIMM50 pathogenic variants reduce the levels and activity of endogenous TIM23 complex, which significantly impacts the mitochondrial proteome, resulting in a combined oxidative phosphorylation (OXPHOS) defect and changes to mitochondrial ultrastructure. Using proteomic data sets from TIMM50 patient fibroblasts and a TIMM50 HEK293 cell model of disease, we reveal that laterally released substrates imported via the TIM23SORT complex pathway are most sensitive to loss of TIMM50. Proteins involved in OXPHOS and mitochondrial ultrastructure are enriched in the TIM23SORT substrate pool, providing a biochemical mechanism for the specific defects in TIMM50-associated mitochondrial disease patients. These results highlight the power of using proteomics to elucidate molecular mechanisms of disease and uncovering novel features of fundamental biology, with the implication that human TIMM50 may have a more pronounced role in lateral insertion than previously understood.
    Keywords:  Mitochondria; TIM23 complex; TIMM50; mitochondrial disease; mitochondrial protein import
    DOI:  https://doi.org/10.1080/10985549.2024.2353652
  5. Nat Commun. 2024 Jun 01. 15(1): 4683
    Structural basis for human mitochondrial tRNA maturation.
    Vincent Meynier, Steven W Hardwick, Marjorie Catala, Johann J Roske, Stephanie Oerum, Dimitri Y Chirgadze, Pierre Barraud, Wyatt W Yue, Ben F Luisi, Carine Tisné.
      The human mitochondrial genome is transcribed into two RNAs, containing mRNAs, rRNAs and tRNAs, all dedicated to produce essential proteins of the respiratory chain. The precise excision of tRNAs by the mitochondrial endoribonucleases (mt-RNase), P and Z, releases all RNA species from the two RNA transcripts. The tRNAs then undergo 3'-CCA addition. In metazoan mitochondria, RNase P is a multi-enzyme assembly that comprises the endoribonuclease PRORP and a tRNA methyltransferase subcomplex. The requirement for this tRNA methyltransferase subcomplex for mt-RNase P cleavage activity, as well as the mechanisms of pre-tRNA 3'-cleavage and 3'-CCA addition, are still poorly understood. Here, we report cryo-EM structures that visualise four steps of mitochondrial tRNA maturation: 5' and 3' tRNA-end processing, methylation and 3'-CCA addition, and explain the defined sequential order of the tRNA processing steps. The methyltransferase subcomplex recognises the pre-tRNA in a distinct mode that can support tRNA-end processing and 3'-CCA addition, likely resulting from an evolutionary adaptation of mitochondrial tRNA maturation complexes to the structurally-fragile mitochondrial tRNAs. This subcomplex can also ensure a tRNA-folding quality-control checkpoint before the sequential docking of the maturation enzymes. Altogether, our study provides detailed molecular insight into RNA-transcript processing and tRNA maturation in human mitochondria.
    DOI:  https://doi.org/10.1038/s41467-024-49132-0
  6. Aging Cell. 2024 Jun 03. e14229
    A novel senolytic drug for pulmonary fibrosis: BTSA1 targets apoptosis of senescent myofibroblasts by activating BAX.
    Mengxia Shen, Jiafeng Fu, Yunna Zhang, Yanfen Chang, Xiaohong Li, Haipeng Cheng, Yujia Qiu, Min Shao, Yang Han, Yan Zhou, Ziqiang Luo.
      Idiopathic pulmonary fibrosis is a progressive and age-related disease that results from impaired lung repair following injury. Targeting senescent myofibroblasts with senolytic drugs attenuates pulmonary fibrosis, revealing a detrimental role of these cells in pulmonary fibrosis. The mechanisms underlying the occurrence and persistence of senescent myofibroblasts in fibrotic lung tissue require further clarification. In this study, we demonstrated that senescent myofibroblasts are resistant to apoptosis by upregulating the proapoptotic protein BAX and antiapoptotic protein BCL-2 and BCL-XL, leading to BAX inactivation. We further showed that high levels of inactive BAX-mediated minority mitochondrial outer membrane permeabilization (minority MOMP) promoted DNA damage and myofibroblasts senescence after insult by a sublethal stimulus. Intervention of minority MOMP via the inhibition of caspase activity by quinolyl-valyl-O-methylaspartyl-[2,6-difluorophenoxy]-methyl ketone (QVD-OPH) or BAX knockdown significantly reduced DNA damage and ultimately delayed the progression of senescence. Moreover, the BAX activator BTSA1 selectively promoted the apoptosis of senescent myofibroblasts, as BTSA1-activated BAX converted minority MOMP to complete MOMP while not injuring other cells with low levels of BAX. Furthermore, therapeutic activation of BAX with BTSA1 effectively reduced the number of senescent myofibroblasts in the lung tissue and alleviated both reversible and irreversible pulmonary fibrosis. These findings advance the understanding of apoptosis resistance and cellular senescence mechanisms in senescent myofibroblasts in pulmonary fibrosis and demonstrate a novel senolytic drug for pulmonary fibrosis treatment.
    Keywords:  BAX; BTSA1; apoptosis; cellular senescence; idiopathic pulmonary fibrosis; myofibroblast
    DOI:  https://doi.org/10.1111/acel.14229
  7. bioRxiv. 2024 May 26. pii: 2024.05.23.595605. [Epub ahead of print]
    Senescent-like microglia limit remyelination through the senescence associated secretory phenotype.
    Phillip S Gross, Violeta Duran Laforet, Zeeba Manavi, Sameera Zia, Sung Hyun Lee, Nataliia Shults, Sean Selva, Enrique Alvarez, Jason R Plemel, Dorothy P Schafer, Jeffrey K Huang.
      The capacity to regenerate myelin in the central nervous system (CNS) diminishes with age. This decline is particularly evident in multiple sclerosis (MS), which has been suggested to exhibit features of accelerated biological aging. Whether cellular senescence, a hallmark of aging, contributes to remyelination impairment remains unknown. Here, we show that senescent cells (SCs) accumulate within demyelinated lesions after injury, and their elimination enhances remyelination in young mice but not in aged mice. In young mice, we observed the upregulation of senescence-associated transcripts primarily in microglia after demyelination, followed by their reduction during remyelination. However, in aged mice, senescence-associated factors persisted within lesions, correlating with inefficient remyelination. We found that SC elimination enhanced remyelination in young mice but was ineffective in aged mice. Proteomic analysis of senescence-associated secretory phenotype (SASP) revealed elevated levels of CCL11/Eotaxin-1 in lesions, which was found to inhibit efficient oligodendrocyte maturation. These results suggest therapeutic targeting of SASP components, such as CCL11, may improve remyelination in aging and MS.
    DOI:  https://doi.org/10.1101/2024.05.23.595605
  8. Nature. 2024 Jun 05.
    Senescent glia link mitochondrial dysfunction and lipid accumulation.
    China N Byrns, Alexandra E Perlegos, Karl N Miller, Zhecheng Jin, Faith R Carranza, Palak Manchandra, Connor H Beveridge, Caitlin E Randolph, V Sai Chaluvadi, Shirley L Zhang, Ananth R Srinivasan, F C Bennett, Amita Sehgal, Peter D Adams, Gaurav Chopra, Nancy M Bonini.
      Senescence is a cellular state linked to ageing and age-onset disease across many mammalian species1,2. Acutely, senescent cells promote wound healing3,4 and prevent tumour formation5; but they are also pro-inflammatory, thus chronically exacerbate tissue decline. Whereas senescent cells are active targets for anti-ageing therapy6-11, why these cells form in vivo, how they affect tissue ageing and the effect of their elimination remain unclear12,13. Here we identify naturally occurring senescent glia in ageing Drosophila brains and decipher their origin and influence. Using Activator protein 1 (AP1) activity to screen for senescence14,15, we determine that senescent glia can appear in response to neuronal mitochondrial dysfunction. In turn, senescent glia promote lipid accumulation in non-senescent glia; similar effects are seen in senescent human fibroblasts in culture. Targeting AP1 activity in senescent glia mitigates senescence biomarkers, extends fly lifespan and health span, and prevents lipid accumulation. However, these benefits come at the cost of increased oxidative damage in the brain, and neuronal mitochondrial function remains poor. Altogether, our results map the trajectory of naturally occurring senescent glia in vivo and indicate that these cells link key ageing phenomena: mitochondrial dysfunction and lipid accumulation.
    DOI:  https://doi.org/10.1038/s41586-024-07516-8
  9. Anal Chem. 2024 Jun 04.
    Lighting Up Nucleolus To Report Mitochondria Damage Using a Mitochondria-to-Nucleolus Migration Probe.
    Yumeng Wang, Qiaowen Lin, Yang Liu, Chi Li, Zhiqiang Liu, Xiaoqiang Yu, Kang-Nan Wang.
      Visualization of the mitochondrial state is crucial for tracking cell life processes and diagnosing disease, while fluorescent probes that can accurately assess mitochondrial status are currently scarce. Herein, a fluorescent probe named "SYN" was designed and prepared, which can target mitochondria via the mitochondrial membrane potential. Upon pathology or external stimulation, SYN can be released from the mitochondria and accumulate in the nucleolus to monitor the status of mitochondria. During this process, the brightness of the nucleolus can then serve as an indicator of mitochondrial damage. SYN has demonstrated excellent photostability in live cells as well as an extremely inert fluorescence response to bioactive molecules and the physiological pH environment of live cells. Spectroscopic titration and molecular docking studies have revealed that SYN can be lit up in nucleoli due to the high viscosity of the nucleus and the strong electrostatic interaction with the phosphate backbone of RNA. This probe is expected to be an exceptional tool based on its excellent imaging properties for tracking mitochondrial state in live cells.
    DOI:  https://doi.org/10.1021/acs.analchem.3c05629
  10. Commun Biol. 2024 Jun 05. 7(1): 691
    Apoptosis signal-regulating kinase 1 promotes inflammation in senescence and aging.
    Takeru Odawara, Shota Yamauchi, Hidenori Ichijo.
      Cellular senescence is a stress-induced, permanent cell cycle arrest involved in tumor suppression and aging. Senescent cells secrete bioactive molecules such as pro-inflammatory cytokines and chemokines. This senescence-associated secretory phenotype (SASP) has been implicated in immune-mediated elimination of senescent cells and age-associated chronic inflammation. However, the mechanisms regulating the SASP are incompletely understood. Here, we show that the stress-responsive kinase apoptosis signal-regulating kinase 1 (ASK1) promotes inflammation in senescence and aging. ASK1 is activated during senescence and increases the expression of pro-inflammatory cytokines and chemokines by activating p38, a kinase critical for the SASP. ASK1-deficient mice show impaired elimination of oncogene-induced senescent cells and an increased rate of tumorigenesis. Furthermore, ASK1 deficiency prevents age-associated p38 activation and inflammation and attenuates glomerulosclerosis. Our results suggest that ASK1 is a driver of the SASP and age-associated chronic inflammation and represents a potential therapeutic target for age-related diseases.
    DOI:  https://doi.org/10.1038/s42003-024-06386-0
  11. Mol Cell Biochem. 2024 Jun 04.
    Mitophagy in relation to chronic inflammation/ROS in aging.
    Liang Kong, Shuhao Li, Yu Fu, Qinyun Cai, Xinyun Du, Jingyan Liang, Tan Ma.
      Various assaults on mitochondria occur during the human aging process, contributing to mitochondrial dysfunction. This mitochondrial dysfunction is intricately connected with aging and diseases associated with it. In vivo, the accumulation of defective mitochondria can precipitate inflammatory and oxidative stress, thereby accelerating aging. Mitophagy, an essential selective autophagy process, plays a crucial role in managing mitochondrial quality control and homeostasis. It is a highly specialized mechanism that systematically removes damaged or impaired mitochondria from cells, ensuring their optimal functioning and survival. By engaging in mitophagy, cells are able to maintain a balanced and stable environment, free from the potentially harmful effects of dysfunctional mitochondria. An ever-growing body of research highlights the significance of mitophagy in both aging and age-related diseases. Nonetheless, the association between mitophagy and inflammation or oxidative stress induced by mitochondrial dysfunction remains ambiguous. We review the fundamental mechanisms of mitophagy in this paper, delve into its relationship with age-related stress, and propose suggestions for future research directions.
    Keywords:  Aging; Chronic inflammation; Mitophagy; ROS
    DOI:  https://doi.org/10.1007/s11010-024-05042-9
  12. bioRxiv. 2024 May 23. pii: 2024.05.21.595226. [Epub ahead of print]
    Cardiolipin clustering promotes mitochondrial membrane dynamics.
    Kelly E Zuccaro, Luciano A Abriata, Fernando Teixeira Pinto Meireles, Frank R Moss, Adam Frost, Matteo Dal Peraro, Halil Aydin.
      Cardiolipin (CL) is a mitochondria-specific phospholipid that forms heterotypic interactions with membrane-shaping proteins and regulates the dynamic remodeling and function of mitochondria. However, the precise mechanisms through which CL influences mitochondrial morphology are not well understood. In this study, employing molecular dynamics (MD) simulations, we observed CL localize near the membrane-binding sites of the mitochondrial fusion protein Optic Atrophy 1 (OPA1). To validate these findings experimentally, we developed a bromine-labeled CL probe to enhance cryoEM contrast and characterize the structure of OPA1 assemblies bound to the CL-brominated lipid bilayers. Our images provide direct evidence of interactions between CL and two conserved motifs within the paddle domain (PD) of OPA1, which control membrane-shaping mechanisms. We further observed a decrease in membrane remodeling activity for OPA1 in lipid compositions with increasing concentrations of monolyso-cardiolipin (MLCL). Suggesting that the partial replacement of CL by MLCL accumulation, as observed in Barth syndrome-associated mutations of the tafazzin phospholipid transacylase, compromises the stability of protein-membrane interactions. Our analyses provide insights into how biological membranes regulate the mechanisms governing mitochondrial homeostasis.
    Teaser: This study reveals how CL modulates the activity of OPA1 and how MLCL impacts its ability to govern mitochondrial function.
    DOI:  https://doi.org/10.1101/2024.05.21.595226
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