bims-nenemi 2025-07-27 papers

bims-nenemi

Biomed News

on Neuroinflammation, neurodegeneration and mitochondria

Issue of 2025–07–27
24 papers selected by
Marco Tigano, Thomas Jefferson University

PDK4 and nutrient responses explain muscle specific manifestation in mitochondrial disease.
MITF promotes MFN2-dependent mitochondrial fusion to protect retinal pigment epithelial cells from mitochondrial damage.
Metastatic breast cancer cells are selectively dependent on the mitochondrial cristae-shaping protein OPA1.
Structure of human mitochondrial pyruvate carrier MPC1 and MPC2 complex.
LONP1 regulation of mitochondrial protein folding provides insight into beta cell failure in type 2 diabetes.
Cell type-specific purifying selection of synonymous mitochondrial DNA variation.
Mitophagy modulation rescues single large-scale mitochondrial DNA deletion (SLSMD) disease symptoms in the C. elegans uaDf5 animal model.
TMEM65 functions as the mitochondrial Na+/Ca2+ exchanger.
Genetically Encoded Photocatalysis for Spatiotemporally Resolved Mapping of Biomolecules in Living Cells and Animals.
RIPK4-mediated MFN2 degradation drives osteogenesis through mitochondrial fragmentation and restricts myelopoiesis by blocking mitochondrial transfer.
Single-molecule live imaging of subunit interactions and exchange within cellular regulatory complexes.
Molecular features of TNBC govern heterogeneity in the response to radiation and autophagy inhibition.
Activation of the integrated stress response and loss of cFLIPL under glutamine limitation induce IL-8 gene expression and secretion in glutamine-dependent tumor cells.
Implications of mtDNA in human health and diseases.
Deletion of gasdermin D promotes granulocytic myeloid-derived suppressor cell differentiation by decreased release of mitochondrial DNA to promote tumor escape.
hnRNPA2B1 recognizes RNA virus SFTSV infection through mitochondrial DNA.
Protocol for generation of transmitochondrial cybrids under pyruvate/uridine-supplemented conditions using a microfluidic device.
Pseudohypoxic stabilization of HIF1α via cyclophilin D suppression promotes melanoma metastasis.
POLRMT enhances lenvatinib resistance in hepatocellular carcinoma cells by maintaining mitochondrial ATP production.
ATP Supply from Cytosol to Mitochondria Is an Additional Role of Aerobic Glycolysis to Prevent Programmed Cell Death by Maintenance of Mitochondrial Membrane Potential.
Regulation of inflammatory responses by pH-dependent transcriptional condensates.
Mitochondrial DNA leakage and micronucleus formation activate the cGAS-STING pathway in aristolochic acid I-induced nephritis.
Mitochondrial bioenergetic failure in SLE immunocytes: Targeting fitness for therapy.
Perturbing the mitochondrial pores using inhibitors of bax and bid along with cyclosporine-A could prevent cell death due to secondary injury after contusion spinal cord injury.

Clin Transl Med. 2025 Jul;15(7): e70404

PDK4 and nutrient responses explain muscle specific manifestation in mitochondrial disease.

Swagat Pradhan, Takayuki Mito, Nahid A Khan, Sofiia Olander, Aleksandra Zhaivoron, Thomas G McWilliams, Anu Suomalainen.

   BACKGROUND: Mitochondria elicit various metabolic stress responses, the roles of which in diseases are poorly understood. Here, we explore how different muscles of one individual-extraocular muscles (EOMs) and quadriceps femoris (QFs) muscles-respond to mitochondrial disease. The aim is to explain why EOMs atrophy early in the disease, unlike other muscles.
METHODS: We used a mouse model for mitochondrial myopathy ("deletor"), which manifests progressive respiratory chain deficiency and human disease hallmarks in itsmuscles. Analyses included histology, ultrastructure, bulk and single-nuclear RNA-sequencing, metabolomics, and mitochondrial turnover assessed through in vivo mitophagy using transgenic mito-QC marker mice crossed to deletors.
RESULTS: In mitochondrial muscle disease, large QFs upregulate glucose uptake that drives anabolic glycolytic one-carbon metabolism and mitochondrial integrated stress response. EOMs, however, react in an opposite manner, inhibiting glucose and pyruvate oxidation by activating PDK4, a pyruvate dehydrogenase kinase and inhibitor. Instead, EOMs upregulate acetyl-CoA synthesis and fatty-acid oxidation pathways, and accumulate lipids. In QFs, Pdk4 transcription is not induced.- Amino acid levels are increased in QFs but are low in EOMs suggesting their catabolic use for energy metabolism. Mitophagy is stalled in both muscle types, in the most affected fibers.
CONCLUSIONS: Our evidence indicates that different muscles respond differently to mitochondrial disease even in one individual. While large muscles switch to anabolic mode and glycolysis, EOMs actively inhibit glucose usage. They upregulate lipid oxidation pathway, a non-optimal fuel choice in mitochondrial myopathy, leading to lipid accumulation and possibly increased reliance on amino acid oxidation. We propose that these consequences of non-optimal nutrient responses lead to EOMatrophy and progressive external ophthalmoplegia in patients. Our evidence highlights the importance of PDK4 and aberrant nutrient signaling underlying muscle atrophies.

Keywords:  integrated stress response; mitochondrial disease; mitochondrial myopathy; nutrient signaling; progressive external ophthalmoplegia; pyruvate dehydrogenase kinase

DOI:  https://doi.org/10.1002/ctm2.70404
Free Radic Biol Med. 2025 Jul 16. pii: S0891-5849(25)00840-8. [Epub ahead of print]239 27-42

MITF promotes MFN2-dependent mitochondrial fusion to protect retinal pigment epithelial cells from mitochondrial damage.

Ying-Ao Chen, Wan-Ni Lu, Pingping Li, Tianyin Nie, Yan Li, Rui Zeng, Sen Lin, Meiling Gao, J Fielding Hejtmancik, Ling Hou, Xiaoyin Ma.

  There is growing indication that protecting the retinal pigment epithelium (RPE) against mitochondrial damage is crucial for preventing RPE cell dysfunction and retinal degeneration. However, the molecular mechanisms remain largely unknown. Here, we show that microphthalmia-associated transcription factor (MITF), a potent antioxidant inducer in RPE, promotes mitochondrial fusion in RPE cells and protects them from mitochondrial uncoupler carbonyl cyanide 3-chlorophenylhydrazone (CCCP)-induced mitochondrial damage in ARPE-19 or mouse primary RPE cells ex vivo and Mitf heterozygous mice (Mitf-/+), Mitf-overexpressing transgenic mice (Dct-Mitf) or AAV mediated MITF overexpression mice in vivo. Mechanistically, MITF directly binds to the promoter of Mitofusin 2 (MFN2), a mitochondrial membrane protein that participates in mitochondrial fusion, and activates its transcription. Conversely, the knockdown of MFN2 neutralized the effects of MITF on mitochondrial fusion and mitochondrial damage protection. Intravitreal injection of mitochondria-targeted SkQ-1 nanoparticles effectively protects RPE cells from CCCP-induced damage in the Mitf-/+ mice in vivo. These findings suggest that MITF has an important role in regulating mitochondrial fusion in RPE cells and provides new insights into understanding the mechanisms of MITF deficiency induced RPE abnormalities and retinal degeneration.

Keywords:  MITF; Mitochondria; Mitochondrial fusion; RPE; Retinal degeneration

DOI:  https://doi.org/10.1016/j.freeradbiomed.2025.07.025
Cell Death Dis. 2025 Jul 21. 16(1): 539

Metastatic breast cancer cells are selectively dependent on the mitochondrial cristae-shaping protein OPA1.

Antigoni Diokmetzidou, Aurora Maracani, Anna Pellattiero, Mauricio Cardenas-Rodriguez, Erwan A Rivière, Luca Scorrano.

In breast cancer, the inner mitochondrial membrane fusion protein Optic Atrophy 1 (OPA1) is upregulated and its inhibition reverses acquired chemoresistance. However, it remains unclear whether OPA1 inhibition also targets normal breast cells. We show that OPA1 upregulation is a hallmark of metastatic breast cancer cells, which are selectively susceptible to OPA1 inhibition compared to isogenic normal or localized tumor cells. In an isogenic model spanning normal, transformed, and metastatic breast cancer cells, levels of Mitofusin 1 (MFN1) progressively declined while dynamin related protein 1 (DRP1) became increasingly active, correlating with fragmented mitochondria during cancer progression. Meanwhile, OPA1 levels were elevated in invasive cells characterized by mitochondrial fragmentation, tight cristae, and high respiration. OPA1 deletion selectively reduced metastatic cells mitochondrial respiration, proliferation, and migration. Specific OPA1 inhibitors MYLS22 and Opitor-0 diminished migration and increased death of metastatic cells, underscoring OPA1 as a selective vulnerability of metastatic breast cancer.

DOI: https://doi.org/10.1038/s41419-025-07878-5
Nat Commun. 2025 Jul 21. 16(1): 6700

Structure of human mitochondrial pyruvate carrier MPC1 and MPC2 complex.

Yingyuan Sun, Yaru Wang, Zheng Xing, Dongyu Li, Rong Wang, Baozhi Chen, Ning Zhou, Alyssa Ayala, Benjamin P Tu, Xiaofeng Qi.

The Mitochondrial Pyruvate Carrier (MPC) bridges cytosolic and mitochondrial metabolism by transporting pyruvate into mitochondria for ATP production and biosynthesis of various essential molecules. MPC functions as a heterodimer composed of MPC1 and MPC2 in most mammalian cells. Here, we present the cryogenic electron microscopy (cryo-EM) structures of the human MPC1-2 complex in the mitochondrial intermembrane space (IMS)-open state and the inhibitor-bound in the mitochondrial matrix-open state. Structural analysis shows that the transport channel of MPC is formed by the interaction of transmembrane helix (TM) 1 and TM2 of MPC1 with TM2 and TM1 of MPC2, respectively. UK5099, a potent MPC inhibitor, shares the same binding site with pyruvate at the matrix side of the transport channel, stabilizing MPC in its matrix-open conformation. Notably, a functional W82F mutation in MPC2 leads to the complex in an IMS-open conformation. Structural comparisons across different conformations, combined with yeast rescue assays, reveal the mechanisms of substrate binding and asymmetric conformational changes in MPC during pyruvate transport across the inner mitochondrial membrane (IMM) as well as the inhibitory mechanisms of MPC inhibitors.

DOI: https://doi.org/10.1038/s41467-025-61939-z
Nat Metab. 2025 Jul 21.

LONP1 regulation of mitochondrial protein folding provides insight into beta cell failure in type 2 diabetes.

Jin Li, Yamei Deng, Marie Gasser, Jie Zhu, Emily M Walker, Vaibhav Sidarala, Emma C Reck, Dre L Hubers, Mabelle B Pasmooij, Chun-Shik Shin, Khushdeep Bandesh, Eftyhmios Motakis, Siddhi Nargund, Romy Kursawe, Venkatesha Basrur, Alexey I Nesvizhskii, Michael L Stitzel, David C Chan, Guy A Rutter, Scott A Soleimanpour.

Protein misfolding is a contributor to the development of type 2 diabetes (T2D), but the specific role of impaired proteostasis is unclear. Here we show a robust accumulation of misfolded proteins in the mitochondria of human pancreatic islets from patients with T2D and elucidate its impact on β cell viability through the mitochondrial matrix protease LONP1. Quantitative proteomics studies of protein aggregates reveal that islets from donors with T2D have a signature resembling mitochondrial rather than endoplasmic reticulum protein misfolding. Loss of LONP1, a vital component of the mitochondrial proteostatic machinery, with reduced expression in the β cells of donors with T2D, yields mitochondrial protein misfolding and reduced respiratory function, leading to β cell apoptosis and hyperglycaemia. LONP1 gain of function ameliorates mitochondrial protein misfolding and restores human β cell survival after glucolipotoxicity via a protease-independent effect requiring LONP1-mitochondrial HSP70 chaperone activity. Thus, LONP1 promotes β cell survival and prevents hyperglycaemia by facilitating mitochondrial protein folding. These observations provide insights into the nature of proteotoxicity that promotes β cell loss during the pathogenesis of T2D, which could be considered as future therapeutic targets.

DOI: https://doi.org/10.1038/s42255-025-01333-7
Proc Natl Acad Sci U S A. 2025 Jul 29. 122(30): e2505704122

Cell type-specific purifying selection of synonymous mitochondrial DNA variation.

Caleb A Lareau, Patrick Maschmeyer, Yajie Yin, Jacob C Gutierrez, Ryan S Dhindsa, Anne-Sophie Gribling-Burrer, Sebastian Zielinski, Yu-Hsin Hsieh, Lena Nitsch, Veronika Dimitrova, Benan Nalbant, Frank A Buquicchio, Tsion Abay, Robert R Stickels, Jacob C Ulirsch, Patrick Yan, Fangyi Wang, Zhuang Miao, Katalin Sandor, Bence Daniel, Vincent Liu, Paul L Mendez, Petra Knaus, Manpreet Meyer, William J Greenleaf, Anshul Kundaje, Redmond P Smyth, Mathias Munschauer, Leif S Ludwig, Ansuman T Satpathy.

  While somatic variants are well-characterized drivers of tumor evolution, their influence on cellular fitness in nonmalignant contexts remains understudied. We identified a mosaic synonymous variant (m.7076A > G) in the mitochondrial DNA (mtDNA)-encoded cytochrome c-oxidase subunit 1 (MT-CO1, p.Gly391=), present at homoplasmy in 47% of immune cells from a healthy donor. Single-cell multiomics revealed strong, lineage-specific selection against the m.7076G allele in CD8+ effector memory T cells, but not other T cell subsets, mirroring patterns of purifying selection of pathogenic mtDNA alleles. The limited anticodon diversity of mitochondrial tRNAs forces m.7076G translation to rely on wobble pairing, unlike the Watson-Crick-Franklin pairing used for m.7076A. Mitochondrial ribosome profiling confirmed stalled translation of the m.7076G allele. Functional analyses demonstrated that the elevated translational and metabolic demands of short-lived effector T cells (SLECs) amplify dependence on MT-CO1, driving this selective pressure. These findings suggest that synonymous variants can alter codon syntax, impacting mitochondrial physiology in a cell type-specific manner.

Keywords:  immunology; mitochondria; selection; single-cell

DOI:  https://doi.org/10.1073/pnas.2505704122
bioRxiv. 2024 Oct 27. pii: 2024.10.27.620333. [Epub ahead of print]

Mitophagy modulation rescues single large-scale mitochondrial DNA deletion (SLSMD) disease symptoms in the C. elegans uaDf5 animal model.

Ryan M Mendel, Sofie Matsuno, Alex Lu, Marni J Falk, Suraiya Haroon.

S ingle large s cale m itochondrial DNA (mtDNA) d eletions (SLSMD) underlie a range of sporadic or maternally inherited primary mitochondrial diseases having significant morbidity and mortality, including Pearson syndrome, Kearns-Sayre Syndrome, or Chronic Progressive External Ophthalmoplegia. Therapeutic development has been hindered by limited existing knowledge on mtDNA quality control and a lack of SLSMD animal models. To address this challenge, we utilized the C. elegans heteroplasmic SLSMD strain, uaDf5, to objectively screen for potential therapies. As mitophagy modulation has been implicated in mtDNA homeostasis, we screened a library of mitophagy modulating compounds to determine their comparative effects to rescue mitochondrial unfolded protein (UPR mt ) stress induction in in uaDf5 SLSMD worms. Interestingly, Thiamine was discovered to be an effective positive control, significantly reducing mitochondrial stress in this model. Two lead therapeutic candidates from the mitophagy library screen were Hemin and Celastrol (Tripterin). Celastrol is a mitophagy activating anti-inflammatory and metabolic modifying natural product derived compound, that rescued multiple fitness outcomes (thrashing, development, survival) and reduced the mitochondrial stress in uaDf5 animals in a mitophagy-dependent fashion. This study highlights the utility of the uaDf5 worm model to enable preclinical identification of therapeutic candidate leads for SLSMD-based heteroplasmic mtDNA diseases and identifies possible therapeutic candidates that serve as mitophagy modulators to improve health and specifically reduce heteroplasmy levels in SLSMD diseases.

DOI: https://doi.org/10.1101/2024.10.27.620333
Nat Cell Biol. 2025 Jul 21.

TMEM65 functions as the mitochondrial Na+/Ca2+ exchanger.

Jim Lu Zhang, Yu-Chen Chang, Po-Hsuan Lai, Han-I Yeh, Chen-Wei Tsai, Yu-Lun Huang, Tsung-Yun Liu, I-Chi Lee, North Foulon, Yan Xu, Bing Rao, Hsiu-Man Shih, Yung-Chi Tu, Andres V Reyes, Shou-Ling Xu, Liang Feng, Ming-Feng Tsai.

Mitochondria export Ca2+ via Na+/Ca2+ exchange machinery (mito-NCX) to regulate intracellular Ca2+ signalling and mitochondrial Ca2+ homeostasis. TMEM65 has recently been implicated as essential for mito-NCX, but its mechanisms and roles remain unclear. Here we show that TMEM65 depletion severely impairs mito-NCX. TMEM65 is highly expressed in the heart and brain but absent in the liver, correlating with mito-NCX activity in these tissues. Biochemical and functional analyses reveal that TMEM65 forms a homodimer, containing plausible ion-coordinating residues critical for function. Heterologous expression of TMEM65 induces Na+/Ca2+ exchange in cells lacking native mito-NCX activity. Moreover, purified, liposome-reconstituted TMEM65 exhibits key mito-NCX features. We further identify the binding site for CGP-37157, a potent, widely used mito-NCX inhibitor. Finally, TMEM65 deletion elevates mitochondrial Ca2+ and primes mitochondria to permeability transition. These findings firmly establish TMEM65 as the protein mediating mito-NCX, offering a new therapeutic target for diseases associated with mitochondrial Ca2+ dysregulation.

DOI: https://doi.org/10.1038/s41556-025-01721-x
Acc Chem Res. 2025 Jul 21.

Genetically Encoded Photocatalysis for Spatiotemporally Resolved Mapping of Biomolecules in Living Cells and Animals.

Yuxin Fang, Peng Zou.

ConspectusEngineered photosensitizer proteins, such as miniSOG, KillerRed, and SuperNova, have long been used for light-triggered protein inhibition and cell ablation. Compared to synthetic organic dyes, these genetically encoded tags provide superior spatial precision for subcellular targeting. More recently, the photochemistry of miniSOG has been repurposed for subcellular omics studies. Upon light activation, miniSOG generates reactive oxygen species (ROS) that oxidize nearby nucleic acids or proteins. These oxidized biomolecules can then react with exogenously supplied nucleophilic probes, which introduce bio-orthogonal handles for downstream enrichment and analysis.This labeling strategy, known as photocatalytic proximity labeling (PPL), has emerged as a powerful approach for profiling the molecular architecture of subcellular compartments and identifying RNA or protein interactors of specific targets. The use of light provides exceptional temporal control, enabling labeling windows as short as 1 s. Moreover, PPL readily supports pulse-chase experiments through simple light on/off switching, an advantage not easily achievable with conventional platforms such as APEX or TurboID.In this account, we highlight our recent developments and applications of genetically encoded PPL tools. These include CAP-seq for RNA/DNA labeling, RinID for protein labeling, and LAP-seq/MS/CELL for bioluminescence-activated multi-omic profiling. Together, these tools enable detailed mapping of the cellular biomolecular landscape. For example, CAP-seq revealed enrichment of transcripts encoding secretory and mitochondrial proteins near the endoplasmic reticulum membrane and outer mitochondrial membrane, supporting models of localized translation. Additionally, pulse-chase labeling using RinID in the ER lumen uncovered distinct decay kinetics of secretory proteins.Looking forward, future efforts may focus on developing low-toxicity and low-background chemical probes, engineering red-shifted photosensitizers for deep-tissue and in vivo applications, and integrating multiple proximity labeling (PL) platforms to study organelle contact sites and interorganelle molecular trafficking.

DOI: https://doi.org/10.1021/acs.accounts.5c00390
Nat Commun. 2025 Jul 19. 16(1): 6666

RIPK4-mediated MFN2 degradation drives osteogenesis through mitochondrial fragmentation and restricts myelopoiesis by blocking mitochondrial transfer.

Peng Ding, Xing Wang, Chuan Gao, Yuehan Wei, Gan Li, Wenlei Zhu, Ni Wang, Wan Fu, Qihang Fang, Meng Yao, Yigang Huang, Chenyi Jiang, Youshui Gao, Jing Zhang, Junjie Gao, Qing Zhong, Changqing Zhang.

Human RIPK4 mutation leads to Bartsocas-Papas syndrome (BPS), characterized by severe skin, craniofacial and limb abnormalities. Currently, our understanding of RIPK4's function has focused on epidermal differentiation and development, whether RIPK4 regulates skeletal homeostasis remains largely elusive. Herein, through global RIPK4 ablation in adult mice, we demonstrate that RIPK4 deficiency leads to osteoporosis, promotes myeloid-biased hematopoiesis and osteolineage RIPK4 plays a crucial role in bone formation and myeloid hematopoiesis. Further detailed investigation pinpoints that RIPK4 interacts with mitochondrial fusion protein MFN2 in a kinase-dependent manner. RIPK4 facilitates the phosphorylation of MFN2, which subsequently undergoes degradation through the proteasome pathway and disrupts the dynamic equilibrium of mitochondrial fission and fusion. Additionally, we also show that osteolineage RIPK4 maintains bone marrow myelopoiesis by MFN2-mediated mitochondrial transfer. More interestingly, while osteocytic RIPK4 could modestly influence the osteogenesis, it is insufficient to sustain bone marrow myelopoiesis owing to the limited amount of mitochondria transfer. These findings decipher the essential role of RIPK4 in maintaining skeletal homeostasis and unveil an unappreciated mechanism of RIPK4-MFN2 axis in regulating osteogenesis and bone marrow myelopoiesis.

DOI: https://doi.org/10.1038/s41467-025-61808-9
Mol Cell. 2025 Jul 15. pii: S1097-2765(25)00578-7. [Epub ahead of print]

Single-molecule live imaging of subunit interactions and exchange within cellular regulatory complexes.

Thomas G W Graham, Claire Dugast-Darzacq, Gina M Dailey, Britney Weng, Sathvik Anantakrishnan, Xavier Darzacq, Robert Tjian.

  Cells are built from vast networks of interdependent molecular interactions. Here, we combine proximity-assisted photoactivation (PAPA) with automated fast single-molecule tracking (fSMT) to probe subunit interactions within endogenous protein complexes in live human cells. PAPA-fSMT revealed that the inactive positive transcription elongation factor b (P-TEFb):7SK ribonucleoprotein complex is predominantly mobile, not tethered to chromatin, and detected interaction of specific heterogeneous nuclear ribonucleoproteins (hnRNPs) with the 7SK complex. Cyclin-dependent kinase 9 (Cdk9) inhibition liberated hnRNP R from large RNAs, increased hnRNP R binding to 7SK, and evicted P-TEFb from 7SK within minutes-consistent with rapid, homeostatic negative feedback regulation of P-TEFb by competing protein-RNA interactions. Association with the coactivator BRD4 increased P-TEFb chromatin binding, which depended on the BRD4 bromodomains. Finally, PAPA detected the release of P-TEFb from 7SK by the HIV transcriptional activator Tat. Our results illuminate aspects of P-TEFb regulation that were previously inaccessible in live cells and open a route to probe subunit interactions and exchange within endogenous regulatory complexes.

Keywords:  7SK complex; BRD4; HIV Tat; P-TEFb; PAPA; fSMT; fast single-molecule tracking; heterogeneous nuclear ribonucleoproteins; hnRNP R; hnRNPs; positive transcription elongation factor b; protein-protein interactions; proximity-assisted photoactivation; transcriptional regulation

DOI:  https://doi.org/10.1016/j.molcel.2025.06.028
Cell Death Dis. 2025 Jul 21. 16(1): 540

Molecular features of TNBC govern heterogeneity in the response to radiation and autophagy inhibition.

Patrick Fischer, Maximilian Schmid, Anna Ohradanova-Repic, Rebecca Schneeweiss, Jana Hadatsch, Odysseus Grünert, Johannes Benedum, Anna Röhrer, Felix Staudinger, Philipp Schatzlmaier, Niccolo Bragato, Sandra Barna, Magdalena Engl, Ava Kleinwächter, Dietmar Georg, Joachim Widder, Sylvia Kerschbaum-Gruber, Dea Slade.

Triple negative breast cancer (TNBC) is a heterogeneous and a highly aggressive type of breast cancer. Standard of care for TNBC patients includes surgery, radio-, chemo- and immunotherapy, depending on the stage of the disease. Immunotherapy is ineffective as monotherapy but can be enhanced with taxane chemotherapy or radiotherapy. Radiation can stimulate the immune system by activating the type I interferon (IFN-I) response through cGAS-STING signaling, which recognizes cytosolic double-stranded DNA (dsDNA). Cytosolic dsDNA can be cleared by autophagy, thereby preventing activation of cGAS-STING signaling. Autophagy inhibition was therefore proposed to potentiate the immunostimulatory effects of radiation. Here we show that different molecular features of TNBC cell lines influence the effect of X-ray and carbon ion (C-ion) irradiation and autophagy inhibition on immunogenic signaling. MDA-MB-468, with low basal autophagy and high cytosolic dsDNA, activates the IFN-I response after radiation. In contrast, MDA-MB-231, characterized by high autophagy rates and low cytosolic dsDNA, induces NF-κB signaling and CXCL10 expression upon autophagy inhibition with the VPS34 inhibitor SAR405. Autophagy inhibition in TNBC cells triggers a stronger activation of innate immune cells (monocytes, natural killer cells and dendritic cells) compared to radiation. In BRCA1-mutated MDA-MB-436 cells, C-ion irradiation was more potent compared to X-rays in inducing the NF-κB-driven immunogenic response but failed to activate immune cells. Upregulation of PD-L1 by X-rays, and especially C-ions, may contribute to reduced immune cell activation, underscoring the need for combination strategies with immune checkpoint blockade. Collectively, our study highlights the NF-κB-driven immunostimulatory effects of autophagy inhibition and the importance of understanding the molecular heterogeneity in TNBC with regard to autophagy rates, IFN-I and NF-κB signaling when designing effective treatments that target these pathways.

DOI: https://doi.org/10.1038/s41419-025-07873-w
Cell Death Discov. 2025 Jul 19. 11(1): 332

Activation of the integrated stress response and loss of cFLIPL under glutamine limitation induce IL-8 gene expression and secretion in glutamine-dependent tumor cells.

Rocío Mora-Molina, F Javier Fernández-Farrán, Abelardo López-Rivas, Carmen Palacios.

Growing evidence suggests that the proapoptotic TNF-related apoptosis-inducing ligand receptor 2 (TRAIL-R2/DR5) signaling pathway can also trigger the production of inflammatory cytokines, thereby promoting tumor progression. We recently reported that glutamine depletion impacts the survival of glutamine-dependent tumor cells by activating the TRAIL-R2/DR5-mediated apoptotic machinery. However, it remains unclear whether glutamine limitation activates a TRAIL-R2/DR5-regulated inflammatory response. In this study, we demonstrate that glutamine starvation activates two parallel signaling pathways, leading to the gene expression and secretion of the pro-angiogenic and pro-inflammatory interleukin-8 (IL-8/CXCL8) in tumor cells. Our findings reveal that the amino acid-sensing general control nonderepressible-2 kinase (GCN2)/activating transcription factor 4 (ATF4) signaling axis contributes to the upregulation of IL-8 gene expression in glutamine-deprived tumor cells. Furthermore, our results indicate that the loss of the long isoform of cellular FLICE-inhibitory protein (cFLIPL), which occurs as result of the metabolic stress induced by glutamine limitation, promotes TRAIL-independent activation of the NF-kB pathway via TRAIL-R2/DR5, a key mechanism driving the observed IL-8 upregulation under starvation conditions. Given the severe depletion of glutamine observed in growing tumors, our data suggest that IL-8 secretion, induced by this metabolic stress, may play a significant role in activating inflammatory and angiogenic responses, thereby counteracting apoptosis and ultimately promoting tumor progression.

DOI: https://doi.org/10.1038/s41420-025-02625-3
BioTechnologia (Pozn). 2025 ;106(2): 209-222

Implications of mtDNA in human health and diseases.

Smruthi Seethashankar, Shruti Hariharan, Venkatachalam Deepa Parvathi.

  The maternally inherited autonomous organelles, mitochondria, are responsible for a myriad of functions within the cell. They may contain more than one copy of DNA and can themselves be present in multiple numbers within a cell. The integrity of the mitochondrial genome is affected by variations in DNA copy number or the presence of mutations. Compromising this integrity has been documented to result in disorders affecting various systems. Focusing on such trends could enhance knowledge essential for developing strategies to manage these disorders. Irregular patterns of mitochondrial DNA (mtDNA) copy number (CN) variation have been identified in various cancers. Reduced mtDNA CN has been associated with neurodegenerative disorders, cardiovascular diseases, and kidney disorders. Mutations in the mitochondrial respiratory chain complex have been linked to cardiomyopathy. High rates of mtDNA deletions have been found in aging patients and subjects with Parkinson's disease. While sperm function appears to deteriorate with increased mtDNA CN, oogenesis involves a significant increase to enable the oocyte to achieve fertilization and further development. Prospective therapies to treat mitochondrial diseases may include approaches that aim to reduce the levels of mutant mtDNA below the disease-causing threshold, such as targeted removal of defective mitochondria. Mutations in mitochondrial DNA contribute to various diseases; some single substitutions appear to disrupt the normalcy of more than one organ, underscoring the importance of mitochondrial genome integrity. The presence of mutations and copy number variations may serve as diagnostic markers and also provide insight into prognosis.

Keywords:  cancer; cardiovascular diseases; fertility; mitochondrial diseases; mtDNA; mtDNA CN; neurodegenerative diseases; renal diseases

DOI:  https://doi.org/10.5114/bta/204532
Cancer Immunol Immunother. 2025 Jul 25. 74(9): 277

Deletion of gasdermin D promotes granulocytic myeloid-derived suppressor cell differentiation by decreased release of mitochondrial DNA to promote tumor escape.

Min Gu, Weiwei Chen, Shizhen Ding, Zhijie Lin, Li Qian, Weiming Xiao, Xiaoqin Jia, Guotao Lu, Weijuan Gong.

  Gasdermin D (GSDMD), an effector molecule of cell pyroptosis, is known to be activated in various cells during inflammation. However, the patterns of GSDMD activation in immune regulatory cells such as myeloid-derived suppressor cells (MDSCs) remain unclear. In this study, we found that neutrophils in colorectal cancer (CRC) tissues exhibited reduced GSDMD transcription, as evidenced by a single-cell RNA sequencing result. Consistent with this, cleaved GSDMD expression is negatively correlated with S100A8 in CRC tissues. Additionally, CD15+CD14-LOX1+ cells (G-MDSCs) from the peripheral blood of CRC patients exhibited a significant reduction in GSDMD activation. Mice with ubiquitous GSDMD deficiency bred in a clean environment exhibited a notable increase in G-MDSCs. These GSDMD-/- MDSCs enhanced immunosuppressive activity by both inhibiting effector T-cell activity and promoting regulatory T-cell induction. This enhancement was also observed in GSDMDflox/flox-S100A8Cre mice, in which GSDMD was specifically deleted in MDSCs. The tumor-promoting effects in the GSDMD-/- and GSDMDflox/flox-S100A8Cre mice were abrogated following MDSC depletion, as shown by the use of an anti-DR5 antibody. In the absence of GSDMD, G-MDSCs showed reduced inflammasome activation and decreased production of IL-1β and IL-18. Furthermore, a significant reduction in interferon-related factor 8/7 (IRF8/7) was observed in GSDMD-/- G-MDSCs via bulk RNA sequencing analysis. After treatment with LPS/nigericin, these cells maintained mitochondrial integrity, thus impairing the mtDNA release and the downstream cGAS/STING/TBK1/IRF8/7 signaling axis activation. Reduced IRF8/7 levels were responsible for increased differentiation of GSDMD-/- G-MDSCs. Finally, treatment with a GSDMD recombinant lentivirus injected into in situ tumors significantly inhibited tumor growth and reduced G-MDSC levels, suggesting that a GSDMD-based vaccine could simultaneously exert anti-carcinoma and anti-MDSC effects.

Keywords:  GSDMD; IRF8/7; MDSCs; Tumor escape; mtDNA

DOI:  https://doi.org/10.1007/s00262-025-04104-1
mBio. 2025 Jul 21. e0166825

hnRNPA2B1 recognizes RNA virus SFTSV infection through mitochondrial DNA.

Xin-Bo Huang, Yue Zhang, Jing-Wen Fan, Xin-Yu Yu, Yun-Lan Fang, Jin-Xin Ren, Bin-Yan Liu.

  The heterogeneous nuclear ribonucleoprotein (hnRNPA2B1, hereafter A2B1) was identified as a novel nuclear DNA sensor that mediates antiviral immunity by recognizing viral DNA in the nucleus. However, it remains largely unclear whether A2B1 could function as a nucleic acid pattern-recognition receptor during cytoplasmic RNA virus infection. Severe fever with thrombocytopenia syndrome virus (SFTSV), which causes severe hemorrhagic fever, is a tick-borne RNA virus that poses a serious threat to public health. In this study, we observed that during SFTSV infection, the interaction between A2B1 and SFTSV nucleoprotein (NP) promoted the retention of A2B1 in the cytoplasm. Importantly, the transcription levels of IFNβ and inflammatory cytokines were decreased with A2B1 silenced, similar to the expression levels of p-TBK1 and p-IRF3. We observed that cytoplasmic A2B1 was involved in recognizing mislocated mitochondrial DNA (mtDNA) and triggered the STING-TBK1 axis to potentiate antiviral type I interferon responses. Thus, A2B1 could be identified as a novel cytoplasmic DNA sensor and sense RNA virus SFTSV infection by monitoring mislocalized mtDNA, stimulating antiviral immune response. Our study may provide new insights into host defense against RNA virus infections and should be important for clarifying the complex interaction between A2B1 and virus infection.IMPORTANCEhnRNPA2B1 (hereafter A2B1) has been identified as a novel DNA sensor for surveillance of infection from DNA viruses. SFTSV is an RNA virus that causes SFTS with a high case-fatality rate of up to 45.7%. Although SFTSV could utilize A2B1 in viral RNA synthesis for proliferation, whether SFTSV can be recognized by DNA sensor A2B1 and initiate innate immune response remains unexplored. Our study illustrates a complex interplay where SFTSV nucleoprotein (NP) seizes the newly synthesized A2B1 in the cytoplasm, which senses leaked mitochondrial DNA, leading to the activation of the STING-TBK1 signaling pathway to promote IFNβ production. These findings reveal the role of nuclear DNA sensor A2B1 in sensing RNA virus SFTSV infection in the cytoplasm and expand the new understanding of A2B1 in innate immunity. By targeting the A2B1-STING axis, we can potentially develop novel antiviral therapies against SFTSV and possibly other RNA viral infections.

Keywords:  IFNβ; SFTSV; STING; hnRNPA2B1; mtDNA

DOI:  https://doi.org/10.1128/mbio.01668-25
STAR Protoc. 2025 Jul 17. pii: S2666-1667(25)00359-4. [Epub ahead of print]6(3): 103953

Protocol for generation of transmitochondrial cybrids under pyruvate/uridine-supplemented conditions using a microfluidic device.

Ken-Ichi Wada, Kazuo Hosokawa, Yoshihiro Ito, Mizuo Maeda, Yui Harada, Yoshikazu Yonemitsu.

  Under conventional approaches, selective culture with a pyruvate/uridine (PU)-free medium is essential for generating transmitochondrial cybrids. Here, we present a protocol for generating transmitochondrial cybrids using a microfluidic device, which works even under PU-supplemented conditions. We describe steps for preparation of the microfluidic device, partial cell fusion (mitochondrial transfer), and harvest of transmitochondrial cybrids. We then detail procedures for confirmation of mtDNA repopulation in cybrids and mtDNA typing by restriction fragment length polymorphism (RFLP) analysis. For complete details on the use and execution of this protocol, please refer to Wada et al.1.

Keywords:  Biotechnology and bioengineering; Cell culture; Genetics; Single cell

DOI:  https://doi.org/10.1016/j.xpro.2025.103953
Signal Transduct Target Ther. 2025 Jul 24. 10(1): 231

Pseudohypoxic stabilization of HIF1α via cyclophilin D suppression promotes melanoma metastasis.

Hye-Kyung Park, Sung Hu, So Yeon Kim, Sora Yoon, Nam Gu Yoon, Ji Hye Lee, Wonyoung Choi, Sun-Young Kong, Jong Heon Kim, Dougu Nam, Byoung Heon Kang.

Stabilization of hypoxia-inducible factor 1 alpha (HIF1α), which plays a pivotal role in regulating cellular responses to insufficient oxygen, is implicated in cancer progression, particularly epithelial-mesenchymal transition and metastatic dissemination. Despite its crucial role in tumorigenesis, the precise mechanisms governing HIF1α stabilization under varying tumor microenvironmental conditions are not fully understood. In this study, we show that stabilization of HIF1α in metastasizing melanoma under mild hypoxia is regulated primarily by mitochondrial reactive oxygen species (ROS) rather than by reduced oxygen levels. Activated HIF1α suppresses the expression of cyclophilin D (CypD), a regulator of the mitochondrial permeability transition pore (mPTP), as a reciprocal regulatory mechanism to sustain HIF1 signaling via upregulation of microRNAs miR-23a and miR-27a. Reduced expression of CypD leads to mPTP closure, resulting in elevated mitochondrial calcium accumulation and enhanced oxidative phosphorylation, which in turn increases mitochondrial ROS levels. The ROS then inhibits a prolyl hydroxylase, establishing a pseudohypoxic state that stabilizes HIF1α even in the presence of oxygen. This HIF1-reinforced and mitochondria-driven pseudohypoxic induction is essential for maintaining HIF1 signaling under conditions of mild hypoxia or transient increases in oxygen levels during melanoma metastasis. Overexpression of CypD reversed the pseudohypoxic state and potently inhibited melanoma metastasis. Thus, mitochondria-driven pseudohypoxic induction is critical for sustaining HIF1 signaling in metastasizing cancer cells and can be exploited to develop anti-metastatic therapies.

DOI: https://doi.org/10.1038/s41392-025-02314-8
Life Sci. 2025 Jul 22. pii: S0024-3205(25)00511-9. [Epub ahead of print] 123876

POLRMT enhances lenvatinib resistance in hepatocellular carcinoma cells by maintaining mitochondrial ATP production.

Rui Wang, Boyu Chen, Yibing Pan, Meng Wang, Yunyun Xiao, Dongni Shi, Yanling Wen, Ying Ouyang, Xiangfu Chen, Yue Li, Libing Song, Binhui Xie.

  Lenvatinib is one of first-line therapeutic agents for advanced hepatocellular carcinoma (HCC), yet lenvatinib resistance of tumor resulting in a weak response on many patients. Mitochondrial energy metabolism is environmentally adaptable and has been shown to play a crucial role in tumor resistance to therapy. Therefore, identification of the key regulator of mitochondrial energy metabolism during lenvatinib resistance provides a novel target for drug-resistant HCC. We found that POLRMT upregulated in lenvatinib-resistant HCC and is associated with poor patient prognosis. POLRMT increased oxidative phosphorylation levels and mitochondrial ATP production through transcriptional upregulation of respiratory chain complexes, which counteracted lenvatinib-induced cellular ATP decrease and the AMPK-caspase 3 signaling pathway. Furthermore, using IMT1B, a specific inhibitor of POLRMT, resensitized the resistant HCC to lenvatinib in vitro and in vivo. This study highlights the critical role of POLRMT in maintaining mitochondrial ATP production, and suggests that POLRMT could serve as a novel prognostic biomarker and potential therapeutic target for lenvatinib-resistant HCC.

Keywords:  Lenvatinib resistance; Mitochondria; Oxidative phosphorylation; POLRMT

DOI:  https://doi.org/10.1016/j.lfs.2025.123876
Metabolites. 2025 Jul 07. pii: 461. [Epub ahead of print]15(7):

ATP Supply from Cytosol to Mitochondria Is an Additional Role of Aerobic Glycolysis to Prevent Programmed Cell Death by Maintenance of Mitochondrial Membrane Potential.

Akane Sawai, Takeo Taniguchi, Kohsuke Noguchi, Taisuke Seike, Nobuyuki Okahashi, Masak Takaine, Fumio Matsuda.

  Eukaryotic cells generate ATP primarily via oxidative and substrate-level phosphorylation. Despite the superior efficiency of oxidative phosphorylation, eukaryotic cells often use both pathways as aerobic glycolysis, even in the presence of oxygen. However, its role in cell survival remains poorly understood. Objectives: In this study, aerobic glycolysis was compared between the Warburg effect in breast cancer cells (MCF7) and the Crabtree effect in a laboratory strain of Saccharomyces cerevisiae (S288C). Methods: The metabolic adaptations of MCF7 and S288C cells were compared following treatment with electron transport chain inhibitors, including FCCP, antimycin A, and oligomycin. Results: MCF7 and S288C cells exhibited strikingly similar metabolic rewiring toward substrate-level phosphorylation upon inhibitor treatment, suggesting that mitochondrial oxidative phosphorylation and cytosolic substrate-level phosphorylation communicate through a common mechanism. Measurement of mitochondrial membrane potential (MMP) and ATP concentrations further indicated that cytosolic ATP was transported into the mitochondria under conditions of reduced electron transport chain activity. This ATP was likely utilized in the reverse mode of H+/ATPase to maintain MMP, which contributed to the avoidance of programmed cell death. Conclusions: These results suggest that the ATP supply to mitochondria plays a conserved role in aerobic glycolysis in yeast and mammalian cancer cells. This mechanism likely contributes to cell survival under conditions of fluctuating oxygen availability.

Keywords:  Saccharomyces cerevisiae; aerobic glycolysis; breast cancer cells; metabolic rewiring; mitochondrial membrane potential; programmed cell death; reverse mode of H+/ATPase

DOI:  https://doi.org/10.3390/metabo15070461
Cell. 2025 Jul 12. pii: S0092-8674(25)00735-4. [Epub ahead of print]

Regulation of inflammatory responses by pH-dependent transcriptional condensates.

Zhongyang Wu, Scott D Pope, Nasiha S Ahmed, Diana L Leung, Yu Hong, Stephanie Hajjar, Cathleen Krabak, Zhe Zhong, Krishnan Raghunathan, Qiuyu Yue, Diya M Anand, Elizabeth B Kopp, Daniel Okin, Weiyi Ma, Ivan Zanoni, Jonathan C Kagan, Jay R Thiagarajah, Diana C Hargreaves, Ruslan Medzhitov, Xu Zhou.

  Inflammation is an essential defense response but operates at the cost of normal tissue functions. Whether and how the negative impact of inflammation is monitored remains largely unknown. Acidification of the tissue microenvironment is associated with inflammation. Here, we investigated whether macrophages sense tissue acidification to adjust inflammatory responses. We found that acidic pH restructured the inflammatory response of macrophages in a gene-specific manner. We identified mammalian BRD4 as an intracellular pH sensor. Acidic pH disrupts transcription condensates containing BRD4 and MED1 via histidine-enriched intrinsically disordered regions. Crucially, a decrease in macrophage intracellular pH is necessary and sufficient to regulate transcriptional condensates in vitro and in vivo, acting as negative feedback to regulate the inflammatory response. Collectively, these findings uncovered a pH-dependent switch in transcriptional condensates that enables environment-dependent control of inflammation, with a broader implication for calibrating the magnitude and quality of inflammation by the inflammatory cost.

Keywords:  BRD4; IDR; acidosis; gene expression; histidine; inflammatory response; innate immunity; macrophage; pH; transcriptional condensates

DOI:  https://doi.org/10.1016/j.cell.2025.06.033
Food Chem Toxicol. 2025 Jul 16. pii: S0278-6915(25)00416-8. [Epub ahead of print]204 115648

Mitochondrial DNA leakage and micronucleus formation activate the cGAS-STING pathway in aristolochic acid I-induced nephritis.

Yu Yang Lei, Yu Shi Hu, Yi Yi Cao, Jing Xi, Yu Ning Ma, Xiao Hong Zhang, Qin Wen Gao, Ji An Fu, Xin Yu Zhang, Li Su, Yang Luan.

  Aristolochic acid I (AAI), a compound in Aristolochiaceae family of plants, has carcinogenic and nephrotoxic effects. However, medicinal and environmental AAI exposure persists. The genotoxic impacts of AAI are reasonably well understood; however, the mechanisms governing its nephrotoxicity and the underlying interaction between its genotoxicity and nephrotoxic characteristics remain elusive. Here, we uncovered a link between AAI-induced DNA damage and the activation of the cGAS-STING pathway, a previously unidentified participant in nephritis. We hypothesized that AAI-induced oxidative stress and genetic damage trigger the release of mitochondrial and micronuclear DNA, which, in turn, activates the cGAS-STING pathway. This mechanism has been validated separately in animal models at a dosage of 15 mg/kg of AAI and in vitro cultures at the IC50 doses. The findings of the involvement of the cGAS-STING pathway, particularly the participation of micronuclear DNA, not only help to understand the nature of AAI-induced nephrotoxicity but also have broader implications for the study of other genotoxic substances, offering potential strategies for mitigating their detrimental effects.

Keywords:  Aristolochic acid I; Genotoxicity; Micronuclear DNA; Mitochondrial DNA; Nephritis; cGAS–STING pathway

DOI:  https://doi.org/10.1016/j.fct.2025.115648
Clin Immunol. 2025 Jul 21. pii: S1521-6616(25)00146-9. [Epub ahead of print]280 110571

Mitochondrial bioenergetic failure in SLE immunocytes: Targeting fitness for therapy.

Anjali S Yennemadi, Natasha Jordan, Sophie Diong, Mark Little, Joseph Keane, Gina Leisching.

   BACKGROUND: Systemic Lupus Erythematosus (SLE) is characterized by dysregulated immune responses linked to immunometabolic perturbations. While mitochondrial dysfunction has been implicated in SLE, its cell-type-specific impact on immune subsets remains underexplored.
METHODS: We repurposed existing RNA-seq data from SLE patient peripheral blood mononuclear cells, with a focus on nuclear-encoded mitochondrial (NEmt) genes, as well as mitochondrial genes themselves, to identify differentially expressed genes compared to healthy controls. Mitochondrial stress tests were performed on freshly isolated CD4+ T cells, CD8+ T cells, B cells, and monocytes from SLE patients and healthy donors to assess bioenergetic function.
RESULTS: RNA-seq revealed that both NEmt genes and mitochondrial genes were downregulated in the PBMC population of SLE patients. In situ mitochondrial stress tests revealed significant reductions in oxygen consumption rate (OCR), indicating impaired oxidative phosphorylation (OXPHOS) across all immune subsets, while extracellular acidification rate (ECAR), a marker of glycolysis, remained unchanged. These findings highlight immune-cell-specific mitochondrial bioenergetic failure in SLE, without compensatory glycolytic adaptation.
CONCLUSION: Our results position mitochondrial fitness as a novel therapeutic target in SLE. We propose leveraging high-throughput screening of mitochondria-targeted compounds, including FDA-approved agents, to enhance OXPHOS, regulate mitophagy, or mitigate oxidative stress. This precision-based approach offers a paradigm shift from conventional immunosuppression to metabolic recalibration, with the potential to restore immune homeostasis in SLE. Systemic Lupus Erythematosus (SLE) is characterized by dysregulated immune responses linked to immunometabolic perturbations. While mitochondrial dysfunction has been implicated in SLE, its cell-type-specific impact on immune subsets remains underexplored.Using existing RNA-seq data we focused on nuclear-encoded mitochondrial (NEmt) genes, as well as mitochondrial genes themselves. Mitochondrial stress tests were performed on freshly isolated CD4+ T cells, CD8+ T cells, B cells, and monocytes from SLE patients and healthy donors to assess bioenergetic function.RNA-seq revealed that both NEmt genes and mitochondrial genes were downregulated in the PBMC population of SLE patients. In situ mitochondrial stress tests revealed significant reductions in oxygen consumption rate, indicating impaired oxidative phosphorylation across all immune subsets, while glycolysis remained unchanged. These findings highlight immune-cell-specific bioenergetic failure in SLE and propose mitochondrial fitness as a novel therapeutic target in SLE. This precision-based approach offers a paradigm shift from conventional immunosuppression to metabolic recalibration.

Keywords:  B cells; CD4+ T cells; CD8+ T cells; Metabolic therapy; Mitochondrial dysfunction; Oxidative phosphorylation; Systemic lupus erythematosus

DOI:  https://doi.org/10.1016/j.clim.2025.110571
Biochem Biophys Res Commun. 2025 Jul 16. pii: S0006-291X(25)01088-5. [Epub ahead of print]778 152373

Perturbing the mitochondrial pores using inhibitors of bax and bid along with cyclosporine-A could prevent cell death due to secondary injury after contusion spinal cord injury.

Preeja Chandran, Khaviyaa Chandramohan, Krithika Iyer, Sreelakshmi Kokkatt Balachandran, Felicia Mary Michael, Sankar Venkatachalam.

  Delayed cell death following contusion spinal cord injury (SCI) is mediated through multiple, overlapping apoptotic pathways, including intrinsic, extrinsic, and granzyme-mediated cascades. Mitochondrial permeability transition pore (mPTP) opening plays a central role in the intrinsic pathway by compromising mitochondrial membrane integrity and enabling the release of cytochrome C and apoptosis-inducing factor (AIF), which activate caspase-dependent and -independent mechanisms. In this study, a holistic approach to preventing the intrinsic pathway of apoptosis was undertaken by inhibiting mPTP gating through targeting the responsible proteins, namely, both BAX and BID, key pro-apoptotic Bcl-2 family proteins, along with cyclosporine A, a known inhibitor of the VDAC-ANT-Cyp-D pore complex. In a rodent model of thoracic contusion SCI, intraparenchymal administration of these inhibitors was followed by Western blot analysis of pathway-specific apoptotic markers at 3 and 7 days post-injury. The results demonstrated effective attenuation of intrinsic apoptosis, accompanied by a collateral reduction in extrinsic and granzyme-mediated pathways. Importantly, this inhibition of apoptosis did not exacerbate necrotic progression, indicating a selective and beneficial modulation of secondary cell death mechanisms. These findings provide initial evidence supporting mitochondrial pore-targeted strategies as a promising therapeutic avenue to mitigate apoptosis-driven secondary damage following SCI. Interestingly, it appears targeting just one pathway of apoptosis itself can produce more beneficial effects by collateral inhibition of other pathways as well. Further studies would be required to validate whether the molecular level benefits observed transulate into systemic improvement in functional recovery after contusion SCI.

Keywords:  Apoptosis; Cyclosporine A; Mitochondrial permeability transition pore; Protein inhibitors; Spinal cord injury

DOI:  https://doi.org/10.1016/j.bbrc.2025.152373