bims-nenemi Biomed News
on Neuroinflammation, neurodegeneration and mitochondria
Issue of 2025–06–22
twenty-one papers selected by
Marco Tigano, Thomas Jefferson University
  1. Transcription arrest induces formation of RNA granules in mitochondria.
  2. Chronic Cellular NAD Depletion Activates a Viral Infection-Like Interferon Response Through Mitochondrial DNA Leakage.
  3. ENPP1 governs the metabolic regulation of effector T cells in autoimmunity by detecting cytosolic mitochondrial DNA.
  4. Dysfunctional mitochondria trap proteins in the intermembrane space.
  5. Aneuploidy-induced proteostasis disruption impairs mitochondrial functions and mediates aggregation of mitochondrial precursor proteins through SQSTM1/p62.
  6. pDCs drive immunopathology by sensing oxidized mitochondrial DNA.
  7. PINK1 Deficiency Facilitates Palmitic Acid-Induced Inflammation by Disrupting Mitochondrial Function to Activate mtDNA-cGAS-STING Signaling.
  8. Mitochondrial dysfunction in the regulation of aging and aging-related diseases.
  9. Mitochondrial DNA oxidation propagates autoimmunity by enabling plasmacytoid dendritic cells to induce TFH differentiation.
  10. Lipid nanoparticle delivery of the CRISPR/Cas9 system directly into the mitochondria of cells carrying m.7778G>T mutation in MtDNA (mt-Atp8).
  11. Hexokinase 2 interacts with PINK1 to facilitate mitophagy in astrocytes and restrain inflammation-induced neurotoxicity.
  12. Activation of STING pathway by mitochondrial fission negatively regulates adipogenic differentiation of 3 T3-L1 cells.
  13. The integrated stress response fine-tunes stem cell fate decisions upon serine deprivation and tissue injury.
  14. Mitochondrial innate immune signaling in skeletal muscle adaptation to exercise.
  15. Decreased mitochondrial activity in the demyelinating cerebellum of progressive multiple sclerosis and chronic EAE contributes to Purkinje cell loss.
  16. The immunoproteasome disturbs neuronal metabolism and drives neurodegeneration in multiple sclerosis.
  17. TAK1 inhibition activates pore-forming proteins to block intracellular bacterial growth through modulating mitochondria.
  18. ALS-associated TDP-43 aggregates drive innate and adaptive immune cell activation.
  19. The innate immune receptor NLRX1 is a novel required modulator for mPTP opening: implications for cardioprotection.
  20. Microglia-specific NF-κB signaling is a critical regulator of prion-induced glial inflammation and neuronal loss.
  21. IL-6 trans-signalling is elevated in ALS models and drives TDP-43 induced inflammatory responses in microglia.
  1. Life Sci Alliance. 2025 Sep;pii: e202403082. [Epub ahead of print]8(9):
    Transcription arrest induces formation of RNA granules in mitochondria.
    Katja G Hansen, Autum Baxter-Koenigs, Caroline Am Weiss, Erik McShane, L Stirling Churchman.
      Mitochondrial gene expression regulation is required for the biogenesis of oxidative phosphorylation (OXPHOS) complexes, yet the spatial organization of mitochondrial RNAs (mt-RNAs) remains unknown. Here, we investigated the spatial distribution of mt-RNAs during various cellular stresses using single-molecule RNA-FISH. We discovered that transcription inhibition leads to the formation of distinct RNA granules within mitochondria, which we term inhibition granules. These structures differ from canonical mitochondrial RNA granules and form in response to multiple transcription arrest conditions, including ethidium bromide treatment, specific inhibition or stalling of the mitochondrial RNA polymerase, and depletion of the SUV3 helicase. Inhibition granules appear to stabilize certain mt-mRNAs during prolonged transcription inhibition. This phenomenon coincides with an imbalance in OXPHOS complex expression, where mitochondrial-encoded transcripts decrease while nuclear-encoded subunits remain stable. We found that cells recover from transcription inhibition via resolving the granules, restarting transcription, and repopulating the mitochondrial network with mt-mRNAs within hours. We suggest that inhibition granules may act as a reservoir to help overcome OXPHOS imbalance during recovery from transcription arrest.
    DOI:  https://doi.org/10.26508/lsa.202403082
  2. Aging Cell. 2025 Jun 16. e70135
    Chronic Cellular NAD Depletion Activates a Viral Infection-Like Interferon Response Through Mitochondrial DNA Leakage.
    Claudia C S Chini, Laura Colman, Eduardo Palmieri, Jessica L Strange, Sonu Kashyap, Bing Han, Andres Benitez-Rosendo, Gina L Ciccio Lopez, Sara Peixoto Rabelo, Shreyartha Mukherjee, Gustavo H de Souza, John Varga, Ralph G Meyer, Mirella L Meyer-Ficca, Eduardo N Chini.
      Nicotinamide adenine dinucleotide (NAD) is a key coenzyme involved in energy metabolism, DNA repair, and cellular signaling. While the effects of acute NAD depletion have been better characterized, the consequences of chronic NAD deficiency remain unclear. Here, we investigated the impact of chronic NAD depletion in cultured cells by removing the availability of nicotinamide (NAM), a key precursor for NAD synthesis, from the culture media. In NIH3T3 fibroblasts, NAM depletion caused a dramatic drop in intracellular NAD levels within 2 days. Remarkably, the cells remained viable even after 7-14 days of NAM depletion, despite NAD+ levels falling to less than 10% of control conditions. This chronic NAD depletion led to distinct metabolic alterations. Mitochondrial basal respiration remained unchanged, but cells exhibited reduced spare respiratory and maximal capacities, along with significantly impaired glycolysis. Notably, NAD depletion triggered an interferon-dependent inflammatory response, resembling viral infections. This was driven by cytosolic leakage of mitochondrial DNA (mtDNA) through voltage-dependent anion channel 1 (VDAC1), which activated the cGAS-STING signaling pathway. Inhibition of VDAC oligomerization with VBIT-4, STING signaling with H-151, or mtDNA depletion blocked the upregulation of interferon genes induced by NAM depletion. Similar interferon responses triggered by NAD depletion were observed in IMR90 human fibroblasts and HS5 stromal cells. Our findings reveal a novel link between chronic NAD deficiency, VDAC-mediated mtDNA release to the cytoplasm, and the activation of the inflammatory response, providing new insight into how NAD decline affects cellular metabolic and inflammatory processes.
    DOI:  https://doi.org/10.1111/acel.70135
  3. Cell Rep. 2025 Jun 13. pii: S2211-1247(25)00622-9. [Epub ahead of print]44(6): 115851
    ENPP1 governs the metabolic regulation of effector T cells in autoimmunity by detecting cytosolic mitochondrial DNA.
    Huiyan Ji, Wanwan Jiang, Juan Zhang, Mengdi Liu, Danhua Su, Jiaxin Lei, Lingyi Li, Ming Zheng, Ting Liu, Zhichun Liu, Qinghua Cao, Lin Xu, Sidong Xiong, Zhenke Wen.
      T cells play a pivotal role in the pathogenesis of systemic lupus erythematosus (SLE), yet the underlying molecular mechanisms governing their fate remain elusive. Here, we identify cytosolic mitochondrial DNA (mtDNA) as an intrinsic trigger for driving effector T cell differentiation in patients with SLE. Specifically, accumulated cytosolic mtDNA is sensed by ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), which enhances the transcription of GLUT1 and glycolysis in SLE T cells. This metabolic shift reduces lipogenesis and depletes free fatty acids (FFAs), impairing the N-myristylation and lysosomal localization of AMP-activated protein kinase (AMPK). Inactive AMPK fails to restrain mammalian target of rapamycin complex 1 (mTORC1), leading to its hyperactivation and driving the mal-differentiation of effector T cells. Consequently, interventions targeting ENPP1, glycolysis, AMPK, and mTORC1 effectively inhibit the generation of immunoglobulin (Ig)G anti-double-stranded DNA (dsDNA) and the progression of lupus nephritis in humanized SLE chimeras. Overall, our findings uncover an mtDNA-ENPP1-metabolic axis that governs effector T cell fate in autoimmunity.
    Keywords:  AMPK; CP: Immunology; CP: Molecular biology; ENPP1; SLE; T cell; mitochondrial DNA
    DOI:  https://doi.org/10.1016/j.celrep.2025.115851
  4. EMBO J. 2025 Jun 16.
    Dysfunctional mitochondria trap proteins in the intermembrane space.
    Tamara Flohr, Markus Räschle, Johannes M Herrmann.
      The accumulation of mitochondrial precursor proteins in the cytosol due to mitochondrial dysfunction compromises cellular proteostasis and is a hallmark of diseases. Why non-imported precursors are toxic and how eukaryotic cells prevent their accumulation in the cytosol is still poorly understood. Using a proximity labeling-based assay to globally monitor the intramitochondrial location of proteins, we show that, upon mitochondrial dysfunction, many mitochondrial matrix proteins are sequestered in the intermembrane space (IMS); something we refer to as "mitochondrial triage of precursor proteins" (MitoTraP). MitoTraP is not simply the result of a general translocation block at the level of the inner membrane, but specifically directs a subgroup of matrix proteins into the IMS, many of which are constituents of the mitochondrial ribosome. Using the mitoribosomal protein Mrp17 (bS6m) as a model, we found that IMS sequestration prevents its mistargeting to the nucleus, potentially averting interference with assembly of cytosolic ribosomes. Thus, MitoTraP represents a novel, so far unknown mechanism of the eukaryotic quality control system that protects the cellular proteome against the toxic effects of non-imported mitochondrial precursor proteins.
    Keywords:  Intermembrane Space; Mitochondria; Nucleolus; Protein Targeting; Ribosome
    DOI:  https://doi.org/10.1038/s44318-025-00486-1
  5. Nat Commun. 2025 Jun 17. 16(1): 5328
    Aneuploidy-induced proteostasis disruption impairs mitochondrial functions and mediates aggregation of mitochondrial precursor proteins through SQSTM1/p62.
    Prince Saforo Amponsah, Jan-Eric Bökenkamp, Olha Kurpa, Svenja Lenhard, Anna Myronova, Daniel Osmar Vega Velazquez, Celina Hirschelmann, Christian Behrends, Johannes M Herrmann, Markus Räschle, Zuzana Storchová.
      Aneuploidy, or aberrant chromosomal content, disrupts cellular proteostasis through altered expression of numerous proteins. Aneuploid cells accumulate SQSTM1/p62-positive cytosolic bodies, exhibit impaired protein folding, and show altered proteasomal and lysosomal activity. Here, we employ p62 proximity- and affinity-based proteomics to elucidate p62 interactors in aneuploid cells and observe an enrichment of mitochondrial proteins. Increased protein aggregation and colocalization of p62 with both novel interactors and mitochondrial proteins is further confirmed by microscopy. Compared to parental diploids, aneuploid cells suffer from mitochondrial defects, including perinuclearly-clustered mitochondrial networks, elevated reactive oxygen species levels, reduced mitochondrial DNA abundance, and impaired protein import, leading to cytosolic accumulation of mitochondrial precursor proteins. Overexpression of heat shock proteins in aneuploid cells mitigates protein aggregation and decreases the colocalization of p62 with the mitochondrial protein TOMM20. Thus, proteotoxic stress caused by chromosome gains results in the sequestration of mitochondrial precursor proteins into cytosolic p62-bodies, thereby compromising mitochondrial function.
    DOI:  https://doi.org/10.1038/s41467-025-60857-4
  6. Nat Immunol. 2025 Jun 17.
    pDCs drive immunopathology by sensing oxidized mitochondrial DNA.
    Moshe Arditi, Timothy R Crother.
      
    DOI:  https://doi.org/10.1038/s41590-025-02193-9
  7. Cell Biochem Funct. 2025 Jun;43(6): e70092
    PINK1 Deficiency Facilitates Palmitic Acid-Induced Inflammation by Disrupting Mitochondrial Function to Activate mtDNA-cGAS-STING Signaling.
    Bin Ye, Yingting Pei, Henian Li, Yuqi Jiang, Wenying Jin, Yueqiu Gao, Wen Liu, Xin Guan, Yu Qiao, Xu Gao, Yanfen Zhang, Ning Ma, Hao Chang.
      Metabolic cells exhibit low-grade chronic inflsammation characterized by excessive production and secretion of proinflammatory cytokines and chemokines in response to overnutrition and energy excess. Mitochondrial dysfunction is closely associated with metabolic inflammation. PINK1 (phosphatase and tensin homology-induced putative kinase 1) is a crucial pathway controlling mitochondrial autophagy, essential for maintaining mitochondrial quality control and metabolic homeostasis. The aim of this study was to investigate the role of PINK1 in metabolic inflammation. Our findings indicate that in adipocytes, palmitic acid (PA) activates the expression of PINK1. Additionally, knockdown of PINK1 exacerbates PA-induced adipocyte inflammation. Mechanistically, PINK1 deficiency impairs mitochondrial function, leading to the release of mtDNA and further activation of the cGAS-STING pathway. Therefore, targeting mitochondrial autophagy in adipocytes and the cGAS-STING pathway may represent effective approaches to alleviate the chronic inflammation associated with obesity and related metabolic disorders.
    Keywords:  PINK1; cGAS‐STING; inflammation; mitochondria; obesity
    DOI:  https://doi.org/10.1002/cbf.70092
  8. Cell Commun Signal. 2025 Jun 19. 23(1): 290
    Mitochondrial dysfunction in the regulation of aging and aging-related diseases.
    Xianhong Zhang, Yue Gao, Siyu Zhang, Yiqi Wang, Xinke Pei, Yufei Chen, Jinhui Zhang, Yichen Zhang, Yitian Du, Shauilin Hao, Yujiong Wang, Ting Ni.
      Aging is an irreversible physiological process that progresses with age, leading to structural disorders and dysfunctions of organs, thereby increasing the risk of chronic diseases such as neurodegenerative diseases, diabetes, hypertension, and cancer. Both organismal and cellular aging are accompanied by the accumulation of damaged organelles and macromolecules, which not only disrupt the metabolic homeostasis of the organism but also trigger the immune response required for physiological repair. Therefore, metabolic remodeling or chronic inflammation induced by damaged tissues, cells, or biomolecules is considered a critical biological factor in the organismal aging process. Notably, mitochondria are essential bioenergetic organelles that regulate both catabolism and anabolism and can respond to specific energy demands and growth repair needs. Additionally, mitochondrial components and metabolites can regulate cellular processes through damage-associated molecular patterns (DAMPs) and participate in inflammatory responses. Furthermore, the accumulation of prolonged, low-grade chronic inflammation can induce immune cell senescence and disrupt immune system function, thereby establishing a vicious cycle of mitochondrial dysfunction, inflammation, and senescence. In this review, we first outline the basic structure of mitochondria and their essential biological functions in cells. We then focus on the effects of mitochondrial metabolites, metabolic remodeling, chronic inflammation, and immune responsesthat are regulated by mitochondrial stress signaling in cellular senescence. Finally, we analyze the various inflammatory responses, metabolites, and the senescence-associated secretory phenotypes (SASP) mediated by mitochondrial dysfunction and their role in senescence-related diseases. Additionally, we analyze the crosstalk between mitochondrial dysfunction-mediated inflammation, metabolites, the SASP, and cellular senescence in age-related diseases. Finally, we propose potential strategies for targeting mitochondria to regulate metabolic remodeling or chronic inflammation through interventions such as dietary restriction or exercise, with the aim of delaying senescence. This reviewprovide a theoretical foundation for organismal antiaging strategies.
    Keywords:  Aging-related diseases; Cellular senescence; Chronic inflammation; Metabolic remodelling; Mitochondria
    DOI:  https://doi.org/10.1186/s12964-025-02308-7
  9. Nat Immunol. 2025 Jun 17.
    Mitochondrial DNA oxidation propagates autoimmunity by enabling plasmacytoid dendritic cells to induce TFH differentiation.
    Hongxu Xian, Kosuke Watari, Masafumi Ohira, Jonathan S Brito, Peng He, Janset Onyuru, Elina I Zuniga, Hal M Hoffman, Michael Karin.
      Stress-induced oxidized mitochondrial DNA (Ox-mtDNA) fragments enter the cytoplasm, activating the NLRP3 inflammasome and caspase-1 and enabling gasdermin-D-mediated circulatory release of mtDNA. Elevated amounts of circulating mtDNA, presumably oxidized, have been detected in older individuals and patients with metabolic or autoimmune disorders. Here we show that sustained Ox-mtDNA release, triggered by a prototypical NLRP3 inflammasome activator, induces autoantibody production and glomerulonephritis in mice. Similar autoimmune responses, dependent on plasmacytoid dendritic cells (pDCs) and follicular helper T (TFH) cells, are elicited by in vitro-generated Ox-mtDNA, but not by non-oxidized mtDNA. Although both mtDNA forms are internalized by pDCs and induce interferon-α, only Ox-mtDNA stimulates autocrine interleukin (IL)-1β signaling that induces co-stimulatory molecules and IL-21, which enable mouse and human pDCs to induce functional TFH differentiation, supportive of autoantibody production. These findings underscore the role of pDC-generated IL-1β in autoantibody production and highlight Ox-mtDNA as an important autoimmune trigger, suggesting potential therapeutic opportunities.
    DOI:  https://doi.org/10.1038/s41590-025-02179-7
  10. Sci Rep. 2025 Jun 19. 15(1): 18717
    Lipid nanoparticle delivery of the CRISPR/Cas9 system directly into the mitochondria of cells carrying m.7778G>T mutation in MtDNA (mt-Atp8).
    Kaede Norota, Sen Ishizuka, Misa Hirose, Yusuke Sato, Masatoshi Maeki, Manabu Tokeshi, Saleh M Ibrahim, Hideyoshi Harashima, Yuma Yamada.
      Mitochondrial genome mutations are associated with various diseases and gene therapy targeted to mitochondria has the potential to effectively treat such diseases. Here, we targeted a point mutation in mitochondrial DNA (mtDNA) that can cause mitochondrial diseases via delivery of the clustered, regularly interspaced, short palindromic repeats/Cas9 (CRISPR/Cas9) system to mitochondria using an innovative lipid nanoparticle (LNP) delivery system. To overcome the major barrier of the mitochondrial membrane structure, we investigated a strategy to deliver ribonucleoprotein (RNP) directly to mitochondria via membrane fusion using MITO-Porter, a mitochondria-targeting lipid nanoparticle. First, we constructed RNP-MITO-Porter, in which an RNP was loaded into MITO-Porter using a microfluidic device. Sequence-specific double-strand breaks were confirmed when the constructed RNP-MITO-Porter was applied to isolated mitochondria. Next, the RNP-MITO-Porter was applied to HeLa cells, and a portion of the RNP-MITO-Porter was colocalized with mitochondria and caused sequence-specific double-strand breaks in mtDNA. Finally, RNP-MITO-Porter was successfully delivered to mitochondria of cells derived from a mouse carrying a point mutation (m.7778G > T) in mtDNA (mt-Atp8) (LMSF-N-MTFVB cells), and created double-strand breaks at the target sequence. RNP-MITO-Porter is expected to contribute significantly to the clinical application of mitochondrion-targeted gene therapy.
    Keywords:  CRISPR/Cas9 ribonucleoprotein (RNP); Lipid nanoparticle (LNP); MITO-Porter; Mitochondrial genome editing; Mitochondrial-targeted delivery
    DOI:  https://doi.org/10.1038/s41598-025-03671-8
  11. Cell Rep. 2025 Jun 17. pii: S2211-1247(25)00580-7. [Epub ahead of print]44(6): 115809
    Hexokinase 2 interacts with PINK1 to facilitate mitophagy in astrocytes and restrain inflammation-induced neurotoxicity.
    Jack H Howden, Hanna Hakansson, Manuela Nieto-Rostro, Robyn McAdam, Charles Arber, Nicholas J Brandon, Josef T Kittler.
      Mitochondria are essential for ATP production, calcium buffering, and apoptotic signaling, with mitophagy playing a critical role in removing dysfunctional mitochondria. This study demonstrates that PINK1-dependent mitophagy occurs more rapidly and is less spatially restricted in astrocytes compared to neurons. We identified hexokinase 2 (HK2) as a key regulator of mitophagy in astrocytes, forming a glucose-dependent complex with PINK1 in response to mitochondrial damage. Additionally, exposure to neuroinflammatory stimuli enhances PINK1/HK2-dependent mitophagy, providing neuroprotection. These findings contribute to our understanding of mitophagy mechanisms in astrocytes and underscore the importance of PINK1 in cellular health and function within the context of neurodegenerative diseases.
    Keywords:  CP: Metabolism; CP: Neuroscience; PINK1; Parkinson’s disease; astrocyte; hexokinase; inflammation; metabolism; mitochondria; mitophagy; neurodegeneration
    DOI:  https://doi.org/10.1016/j.celrep.2025.115809
  12. Cell Signal. 2025 Jun 16. pii: S0898-6568(25)00363-8. [Epub ahead of print] 111948
    Activation of STING pathway by mitochondrial fission negatively regulates adipogenic differentiation of 3 T3-L1 cells.
    Kai Ma, Haoxuan Sun, Xiaoyun Wu, Jinping Quan, Rong Tang, Weiwei Liu, Toshihiko Hayashi, Kazunori Mizuno, Shunji Hattori, Hitomi Fujisaki, Takashi Ikejima.
      Adipocyte hyperplasia refers to the increase in the number of adipocytes, whereas adipocyte hypertrophy pertains to the enlargement of individual adipocytes resulting from the accumulation of lipid droplets. In this study, we found that activation of the STING signalling pathway occurs during adipogenic differentiation of 3 T3-L1 preadipocytes. Interestingly, inhibiting the STING pathway by using STING antagonist H151 or siRNA targeting STING promotes adipocyte differentiation and increases adipocyte numbers, while activation of STING inhibits adipogenic differentiation. Silencing the STING canonical downstream IRF3, or inhibiting the proton channel activity of STING enhances adipogenic differentiation, confirming the negative modulation of adipogenic differentiation by STING. In vivo, intraperitoneal injection of H151 into mice with a high-fat diet further enhances the adipocyte hyperplasia, as shown by the increased volume of adipose tissues, but consistent sizes of adipocytes. During the adipogenic differentiation of 3 T3-L1 cells, DRP1-mediated mitochondrial fission is enhanced, and causes mitochondrial DNA leakage, which in turn activates the STING pathway. However, inhibition of mitochondrial fission represses adipogenic differentiation of 3 T3-L1 cells in spite of the down-regulation of STING pathway. Therefore, our results indicate that adipogenic differentiation is associated with DRP1-induced mitochondrial fission. However, the leakage of mitochondrial DNA caused by DRP1-induced mitochondrial fission activates the STING signalling pathway, which negatively regulates adipogenic differentiation. Tissue specific reduction of DRP1-associated mitochondrial fission or STING enhancement might be new strategies for the therapy of obesity-associated diseases.
    Keywords:  3 T3-L1 cells; Adipocyte differentiation; DRP1; Mitochondria; STING
    DOI:  https://doi.org/10.1016/j.cellsig.2025.111948
  13. Cell Metab. 2025 Jun 12. pii: S1550-4131(25)00266-9. [Epub ahead of print]
    The integrated stress response fine-tunes stem cell fate decisions upon serine deprivation and tissue injury.
    Jesse S S Novak, Lisa Polak, Sanjeethan C Baksh, Douglas W Barrows, Marina Schernthanner, Benjamin T Jackson, Elizabeth A N Thompson, Anita Gola, M Deniz Abdusselamoglu, Alain R Bonny, Kevin A U Gonzales, Julia S Brunner, Anna E Bridgeman, Katie S Stewart, Lynette Hidalgo, June Dela Cruz-Racelis, Ji-Dung Luo, Shiri Gur-Cohen, H Amalia Pasolli, Thomas S Carroll, Lydia W S Finley, Elaine Fuchs.
      Epidermal stem cells produce the skin's barrier that excludes pathogens and prevents dehydration. Hair follicle stem cells (HFSCs) are dedicated to bursts of hair regeneration, but upon injury, they can also reconstruct, and thereafter maintain, the overlying epidermis. How HFSCs balance these fate choices to restore physiologic function to damaged tissue remains poorly understood. Here, we uncover serine as an unconventional, non-essential amino acid that impacts this process. When dietary serine dips, endogenous biosynthesis in HFSCs fails to meet demands (and vice versa), slowing hair cycle entry. Serine deprivation also alters wound repair, further delaying hair regeneration while accelerating re-epithelialization kinetics. Mechanistically, we show that HFSCs sense each fitness challenge by triggering the integrated stress response, which acts as a rheostat of epidermal-HF identity. As stress levels rise, skin barrier restoration kinetics accelerate while hair growth is delayed. Our findings offer potential for dietary and pharmacological intervention to accelerate wound healing.
    Keywords:  dietary intervention; epidermal stem cells; fate selection; hair follicle stem cells; hair regrowth; integrated stress response; serine metabolism; tissue regeneration; tissue repair; wound healing
    DOI:  https://doi.org/10.1016/j.cmet.2025.05.010
  14. Trends Endocrinol Metab. 2025 Jun 12. pii: S1043-2760(25)00119-5. [Epub ahead of print]
    Mitochondrial innate immune signaling in skeletal muscle adaptation to exercise.
    Jin Ma, Annie Yujin Son, Youlim Son, Ping-Yuan Wang, Paul M Hwang.
      Exercise-induced inflammation is regarded as a response to muscle damage from mechanical stress, but controlled immune signaling can be beneficial by promoting metabolic adaptation which, for example, decreases obesity and lowers the risk of diabetes. In addition to oxidative metabolism, mitochondria play a central role in initiating innate immune signaling. We review recent work that has identified the cGAS-STING-NF-κB signaling pathway, activated by the downregulation of mitochondrial proteins CHCHD4 and TRIAP1, as mediating skeletal muscle adaptation to exercise training as well as potentially promoting cellular resilience to environmental stresses. Notably, CHCHD4 haploinsufficiency prevents obesity in aging mice; therefore, this innate immune signaling pathway could be targeted to achieve some of the health benefits of exercise.
    Keywords:  CHCHD4; TRIAP1; exercise; fiber type; innate immunity; metabolism; mtDNA; obesity
    DOI:  https://doi.org/10.1016/j.tem.2025.05.004
  15. Proc Natl Acad Sci U S A. 2025 Jun 24. 122(25): e2421806122
    Decreased mitochondrial activity in the demyelinating cerebellum of progressive multiple sclerosis and chronic EAE contributes to Purkinje cell loss.
    Kelley C Atkinson, Shane Desfor, Micah Feri, Maria T Sekyi, Marvellous Osunde, Sandhya Sriram, Saima Noori, Wendy Rincón, Britany Bello, Seema K Tiwari-Woodruff.
      In multiple sclerosis (MS), cerebellar gray matter atrophy, white matter demyelination, and Purkinje cell (PC) loss have been linked to tremors, impaired motor control, and loss of coordination. Similar pathologies have been observed in the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). This study hypothesized that inflammatory demyelination of the cerebellum alters overall mitochondrial function and is a contributor to axon degeneration and PC loss. Postmortem cerebellar tissue from MS patients, particularly those with secondary progressive MS, showed decreased mitochondrial complex IV (COXIV) activity and significant PC loss. Inflammation, PC axon demyelination, axon degeneration, and parallel fiber loss were also evident. These findings were mirrored in late-stage EAE mice, which also showed increased inflammation and demyelination, reduced PC COXIV activity, and overall PC loss. Further analysis of EAE mice revealed altered mitochondrial structure, modified mitochondrial respiration, and reduced levels of mitochondrial genes involved in energy production. These findings indicate that both human MS and mouse EAE share similar cerebellar changes linked to mitochondrial dysfunction. Thus, late-stage EAE is a valuable model for studying MS-related cerebellar pathology, and mitochondria may be a potential therapeutic target for MS treatment.
    Keywords:  COXIV; axon damage; cerebellar pathology; experimental autoimmune encephalomyelitis; mitochondria respiration
    DOI:  https://doi.org/10.1073/pnas.2421806122
  16. Cell. 2025 Jun 13. pii: S0092-8674(25)00616-6. [Epub ahead of print]
    The immunoproteasome disturbs neuronal metabolism and drives neurodegeneration in multiple sclerosis.
    Marcel S Woo, Johannes Brand, Lukas C Bal, Manuela Moritz, Mark Walkenhorst, Vanessa Vieira, Inbal Ipenberg, Nicola Rothammer, Man Wang, Batuhan Dogan, Desirée Loreth, Christina Mayer, Darwin Nagel, Ingrid Wagner, Lena Kristina Pfeffer, Peter Landgraf, Marco van Ham, Kuno M-J Mattern, Ingo Winschel, Noah Frantz, Jana K Sonner, Henrike K Grosshans, Albert Miguela, Simone Bauer, Nina Meurs, Anke Müller, Lars Binkle-Ladisch, Gabriela Salinas, Lothar Jänsch, Daniela C Dieterich, Maria Riedner, Elke Krüger, Frank L Heppner, Markus Glatzel, Victor G Puelles, Jan Broder Engler, Jens Randel Nyengaard, Thomas Misgeld, Martin Kerschensteiner, Doron Merkler, Catherine Meyer-Schwesinger, Manuel A Friese.
      Inflammation, aberrant proteostasis, and energy depletion are hallmarks of neurodegenerative diseases such as multiple sclerosis (MS). However, the interplay between inflammation, proteasomal dysfunction in neurons, and its consequences for neuronal integrity remains unclear. Using transcriptional, proteomic, and functional analyses of proteasomal subunits in inflamed neurons, we found that interferon-γ-mediated induction of the immunoproteasome subunit, proteasome 20S beta 8 (PSMB8) impairs the proteasomal balance, resulting in reduced proteasome activity. This reduction causes the accumulation of phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key metabolic regulator, leading to enhanced neuronal glycolysis, reduced pentose phosphate pathway activity, oxidative injury, and ferroptosis. Neuron-specific genetic and systemic pharmacological targeting of PSMB8 or PFKFB3 protected neurons in vitro and in a mouse model of MS. Our findings provide a unifying explanation for proteasomal dysfunction in MS and possibly other neurodegenerative diseases, linking inflammation to metabolic disruption, and presenting an opportunity for targeted neuroprotective therapies.
    Keywords:  excitotoxicity; ferroptosis; glycolysis; immunoproteasome; interferon-γ; metabolism; multiple sclerosis; neurodegeneration; neuroinflammation
    DOI:  https://doi.org/10.1016/j.cell.2025.05.029
  17. Cell Death Dis. 2025 Jun 18. 16(1): 456
    TAK1 inhibition activates pore-forming proteins to block intracellular bacterial growth through modulating mitochondria.
    Wilfred López-Pérez, Roland E González-Calderón, Kazuhito Sai, Prashant Rai, Jacqueline M MacStudy, Yosuke Sakamachi, Cameron Parsons, Sophia Kathariou, Michael B Fessler, Jun Ninomiya-Tsuji.
      Mitogen-activated protein kinase kinase kinase 7 (MAP3K7), known as TAK1, is a central mediator of intracellular host defense signaling promoting inflammatory gene expression. Hence, TAK1 is a prime target of intracellular bacterial effectors in blocking inflammatory responses. However, when TAK1 is inhibited, host cells alternatively activate multiple cell death pathways, namely caspase 8-dependent apoptosis and pyroptosis, and receptor interacting protein kinase 3 (RIPK3)-dependent necroptosis. While these pathways ultimately lead to cell death, we found that they also modulate mitochondria to produce mitochondrial reactive oxygen species (ROS). Although as cell death executors, mixed lineage kinase-like (MLKL) and gasdermins are known to form pores in the plasma membrane, we found that TAK1 inhibition translocates them to mitochondria resulting in elevated mitochondrial ROS. Ablation of both MLKL and gasdermins diminished TAK1 inhibition-induced elevation of ROS and exacerbated intracellular bacterial colonization. Our results reveal that these cell death pathways have an alternative host defense role to prevent intracellular pathogen colonization.
    DOI:  https://doi.org/10.1038/s41419-025-07760-4
  18. iScience. 2025 Jun 20. 28(6): 112648
    ALS-associated TDP-43 aggregates drive innate and adaptive immune cell activation.
    Baggio A Evangelista, Joey V Ragusa, Kyle Pellegrino, Yijia Wu, Ivana Yoseli Quiroga-Barber, Shannon R Cahalan, Omeed K Arooji, Jillann A Madren, Sally Schroeter, Joe Cozzarin, Ling Xie, Xian Chen, Kristen K White, J Ashley Ezzell, Marie A Iannone, Sarah Cohen, Douglas H Phanstiel, Rick B Meeker, Todd J Cohen.
      Amyotrophic lateral sclerosis (ALS) is the most common and fatal motor neuron disease. Approximately 90% of ALS patients exhibit pathology of the master RNA regulator, transactive response DNA binding protein (TDP-43). Despite the prevalence TDP-43 pathology in ALS motor neurons, recent findings suggest immune dysfunction is a determinant of disease progression in patients. Whether TDP-43 aggregates elicit immune responses remains underexplored. In this study, we demonstrate that TDP-43 aggregates are internalized by antigen-presenting cell populations, cause vesicle rupture, and drive innate and adaptive immune cell activation by way of antigen presentation. Using a multiplex imaging platform, we observed enrichment of activated microglia/macrophages in ALS white matter that correlated with phosphorylated TDP-43 accumulation, CD8 T cell infiltration, and major histocompatibility complex expression. Taken together, this study sheds light on a novel cellular response to TDP-43 aggregates through an immunological lens.
    Keywords:  Immunity; Neuroscience; Omics
    DOI:  https://doi.org/10.1016/j.isci.2025.112648
  19. Basic Res Cardiol. 2025 Jun 19.
    The innate immune receptor NLRX1 is a novel required modulator for mPTP opening: implications for cardioprotection.
    Y Xiao, X Hu, C F Rudolphi, E E Nollet, R Nederlof, Q Wang, D Bakker, Panagiota Efstathia Nikolaou, J C Knol, R R Goeij-de Haas, A A Henneman, T V Pham, C R Jimenez, A E Grootemaat, N N van der Wel, S E Girardin, N Kaludercic, J van der Velden, Z Onódi, P Leszek, Z V Varga, P Ferdinandy, B Preckel, N C Weber, M W Hollmann, F Di Lisa, C J Zuurbier.
      NLRX1 is the only NOD-like innate immune receptor that localises to mitochondria. We previously demonstrated that NLRX1 deletion increased infarct size in isolated mouse hearts subjected to ischemia-reperfusion injury (IRI); however, underlying mechanisms are yet to be identified. Given the crucial role played by mitochondria in cardiac IRI, we here hypothesise that NLRX1 affects key mechanisms of cardiac IRI. Cardiac IRI was evaluated in isolated C57BL/6J (WT) and NLRX1 knock out (KO) mouse hearts. The following known modulators of IRI were explored in isolated hearts, isolated mitochondria; or permeabilised cardiac fibres: 1) mTOR/RISK/autophagy regulation, 2) AMPK and mitochondrial energy production, and 3) mitochondrial permeability transition pore (mPTP) opening. NLRX1 deletion increased IRI, and cardiac NLRX1 was decreased after IRI in mouse and pig hearts. NLRX1 ablation caused decreased mTOR and RISK pathway (Akt, ERK, and S6K) activation following IR, without affecting autophagy/inflammation/oxidative stress markers. The RISK activator Urocortin dissipated NLRX1 effects on mTOR, RISK pathway and IRI, indicating that increased cardiac IRI with NLRX1 deletion is, at least partly, due to impaired RISK activation. The energy sensor AMPK was activated in NLRX1 KO hearts, possibly due to slowed mitochondrial respiratory responses (impaired mitochondrial permeability) towards palmitoylcarnitine in permeabilised cardiac fibres. NLRX1 deletion completely abolished calcium-induced mPTP opening, and cyclosporine A (CsA) effects on mPTP, both before and after IR, and was associated with increased mitochondrial calcium content after IR. Mitochondrial sub-fractionation studies localised NLRX1 to the inner mitochondrial membrane. NLRX1 deletion associated with decreased phosphorylation of mitochondrial Got2, Cx43, Myl2, Ndufb7 and MICOS10. The mPTP inhibitor CsA abolished IRI differences between KO and WT hearts, suggesting that the permanent closure of mPTP due to NLRX1 deletion contributed to the increased IR sensitivity of NLRX1 KO hearts. This is the first demonstration that the mitochondrial NLRX1 is a novel factor required for mPTP opening and contributes to cardioprotection against acute IRI through RISK pathway activation and prevention of permanent mPTP closure.
    Keywords:  AMPK; I/R injury; Mitochondria; Mitochondrial transition pore opening; NLRX1; RISK pathway
    DOI:  https://doi.org/10.1007/s00395-025-01124-x
  20. PLoS Pathog. 2025 Jun 18. 21(6): e1012582
    Microglia-specific NF-κB signaling is a critical regulator of prion-induced glial inflammation and neuronal loss.
    Arielle J D Hay, Katriana A Popichak, Genova Mumford, Jifeng Bian, Payton Shirley, Lauren Wolfrath, Michael Eggers, Eric M Nicholson, Ronald B Tjalkens, Mark D Zabel, Julie A Moreno.
      Prion diseases are a group of rare and fatal neurodegenerative diseases caused by the cellular prion protein, PrPC, misfolding into the infectious form, PrPSc, which forms aggregates in the brain. This leads to activation of glial cells, neuroinflammation, and irreversible neuronal loss, however, the role of glial cells in prion disease pathogenesis and neurotoxicity is poorly understood. Microglia can phagocytose PrPSc, leading to the release of inflammatory signaling molecules, which subsequently induce astrocyte reactivity. Animal models show highly upregulated inflammatory molecules that are a product of the Nuclear Factor-kappa B (NF-κB) signaling pathway, suggesting that this is a key regulator of inflammation in the prion-infected brain. The activation of the IκB kinase complex (IKK) by cellular stress signals is critical for NF-κB-induced transcription of a variety of genes, including pro-inflammatory cytokines and chemokines, and regulators of protein homeostasis and cell survival. However, the contribution of microglial IKK and NF-κB signaling in the prion-infected brain has not been evaluated. Here, we characterize a primary mixed glial cell model containing wild-type (WT) astrocytes and IKK knock-out (KO) microglia. These cultures show a near ablation of microglia compared to WT mixed glial cultures, highlighting the role of IKK in microglial survival and proliferation. We show that, when exposed to prion-infected brain homogenates, NF-κB-associated genes are significantly downregulated, but prion accumulation is significantly increased, in mixed glial cultures containing minimal microglia. Mice with IKK KO microglia show rapid disease progression when intracranially infected with prions, characterized by an increased density of activated microglia and reactive astrocytes, development of spongiosis, and accelerated loss of hippocampal neurons and associated behavioral deficits. These animals display clinical signs of prion disease early and have a 22% shorter life expectancy compared to infected wild-type mice. Intriguingly, PrPSc accumulation was significantly lower in the brains of terminal animals with IKK KO microglia compared to terminal WT mice, suggesting that accelerated disease is independent of PrPSc accumulation, highlighting a glial-specific pathology. Together, these findings present a critical role for microglial IKK and NF-κB signaling in host protection against prion disease.
    DOI:  https://doi.org/10.1371/journal.ppat.1012582
  21. Brain Behav Immun. 2025 Jun 14. pii: S0889-1591(25)00238-7. [Epub ahead of print]129 296-304
    IL-6 trans-signalling is elevated in ALS models and drives TDP-43 induced inflammatory responses in microglia.
    Grace Risby-Jones, Jianina Marallag, Cyril Jones Jagaraj, Julie D Atkin, Adam K Walker, Trent M Woodruff, John D Lee, Jenny N Fung.
      Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by chronic inflammation in both the central nervous system (CNS) and peripheral tissues. Interleukin-6 (IL-6) has been implicated in ALS pathology; however, IL-6 exhibits both anti-inflammatory and pro-inflammatory functions. Notably, IL-6 trans-signalling possesses pro-inflammatory properties and is emerging as a key contributor to neuroinflammation during neurodegeneration. In this study, we aimed to characterize the expression of the IL-6 trans-signalling pathway in ALS mouse models and investigate its role in ALS protein aggregate-mediated inflammation in microglia and peripheral immune cells. Our results revealed that the protein expression level of a key IL-6 trans-signalling component, soluble IL-6 receptor (sIL-6R), was significantly increased in the spinal cord and tibialis anterior (TA) muscles of both SOD1G93A and rNLS8 TDP-43 transgenic mice. Additionally, using mouse primary microglia, human monocyte-derived microglia-like cells (MDMi), and blood peripheral immune cells, we demonstrated that recombinant TDP-43 protein elicits robust pro-inflammatory cytokine responses, including IL-6, TNF-α, IL-23, and MCP-1. These responses were attenuated when treated with a specific IL-6 trans-signalling inhibitor, sgp130Fc. Our findings suggest that the TDP-43-induced inflammatory response is, in part, IL-6 trans-signalling-dependent and highlight the role of IL-6 trans-signalling as a potential driver of chronic inflammation contributing to ALS pathology. These results support IL-6 trans-signalling as a promising therapeutic target for mitigating inflammation and slowing disease progression. Future research should explore the broader implications of modulating IL-6 trans-signalling in ALS.
    Keywords:  IL-6 trans-signalling; Microglia; Neuroinflammation; TDP-43 protein aggregates; sgp130Fc
    DOI:  https://doi.org/10.1016/j.bbi.2025.06.021
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