bims-nenemi 2025-10-05 papers

bims-nenemi

Biomed News

on Neuroinflammation, neurodegeneration and mitochondria

Issue of 2025–10–05
fifteen papers selected by
Marco Tigano, Thomas Jefferson University

Mitochondrial DNA homeostasis: A novel therapeutic target for neurodegenerative diseases.
Cardiolipin dynamics promote membrane remodeling by mitochondrial OPA1.
Integrated multi omics and machine learning reveal mitochondrial immunometabolic networks in sepsis associated encephalopathy.
The PP2A-B55α phosphatase is a master regulator of mitochondrial degradation and biogenesis.
Mitochondrial dynamics and pore formation in regulated cell death pathways.
Endothelial Gasdermin D Induces Mitochondrial Damage and Activates the STING Pathway in Lipopolysaccharide-Accelerated Atherosclerosis.
Interconnectivity of mitochondrial protein biogenesis and quality control.
Establishment of human Leber's hereditary optic neuropathy model using iPSC-derived retinal organoids.
A mouse model of MEPAN demonstrates a role for mitochondrial fatty acid synthesis in iron-sulfur cluster and supercomplex formation.
Proteomic analysis of brain and spinal cord tissue reveals distinct immune and mitochondrial processes between human and mouse ALS models.
Mitochondrial ROS triggers mitophagy through activating the DNA damage response signaling pathway.
Elevated plasma levels of cell-free mtDNA are associated with acute rejection following heart transplantation.
Diabetic heart shows preferential secretion of inner mitochondrial membrane proteins in the presence of mitochondrial oxidative stress.
The role and mechanism of transcription factor KLF4 in regulating mitochondrial damage and apoptosis by activating chondrocyte autophagy in osteoarthritis.
Illuminating Mitochondrial Dynamics: Ultrahigh Labeling Stability Probe for Long-Term SIM Super-Resolution Imaging of Mitochondria.

Neural Regen Res. 2025 Sep 29.

Mitochondrial DNA homeostasis: A novel therapeutic target for neurodegenerative diseases.

Tingting Fu, Xinyi Chen, Shuting Zhang, Ying Fu, Lin Huang, Wandi Xiong.

   ABSTRACT: The mitochondrial genomic homeostasis is essential for the function of the oxidative phosphorylation system and cellular homeostasis. Mitochondrial DNA is particularly susceptible to aging-related oxidative stress due to the lack of a histone coat. Disturbances in mitochondrial DNA may contribute to functional decline during the aging process and in neurodegenerative diseases, leading to further impairment of mitochondrial DNA and initiating a vicious cycle. To date, it remains unclear how disturbed mitochondrial DNA is involved in the etiology of pathological aging and neurodegenerative diseases. The purpose of this review is to clarify the crucial roles of mitochondrial DNA homeostasis in the pathogenesis of neurodegenerative diseases. Mitochondrial DNA is distributed within nucleoids and is then transcribed into polycistronic mitochondrial DNA molecules within the mitochondrial granule region. Within the ultrastructure of the mitochondrial nucleoid and granule, a group of essential mitochondrial proteins involved in DNA replication, DNA transcription, RNA translation, RNA surveillance, and RNA degradation plays a crucial role in maintaining mitochondrial structure, genome integrity, and mitochondrial DNA processing. The uniparentally inherited mitochondrial DNA undergoes heritable polyploid variations, which include homoplasmy and heteroplasmy. Accumulating mitochondrial DNA alterations, such as deletions, point mutations, and methylations, occur during the pathogenic processes of neurodegenerative diseases. The increased mitochondrial DNA alterations can be propagated by the rise of deleterious heteroplasmy in neurodegenerative diseases, ultimately resulting in impairment to the oxidative phosphorylation system, biogenesis defects, and cellular metabolic dysfunction. Therefore, developing appropriate gene editing tools to rectify aberrant alterations in mitochondrial DNA and targeting the key proteins involved in maintaining mitochondrial DNA homeostasis can be considered promising therapeutic strategies for neurodegenerative diseases. Although therapeutic strategies targeting mitochondrial DNA in diseases show great potential, challenges related to efficacy and safety require a better understanding of the mechanisms underlying mitochondrial DNA alterations in aging and neurodegenerative diseases.

Keywords:  Alzheimer’s disease; Parkinson’s disease; aging; heteroplamy; mitochondrial DNA; mitochondrial DNA mutation; mitochondrial genome; mitochondrial haplogroup; mitochondrial homeostasis; neurodegenerative diseases

DOI:  https://doi.org/10.4103/NRR.NRR-D-25-00495
Nat Commun. 2025 Sep 30. 16(1): 8685

Cardiolipin dynamics promote membrane remodeling by mitochondrial OPA1.

Sirikrishna Thatavarthy, Luciano A Abriata, Fernando Teixeira Pinto Meireles, Kelly E Zuccaro, Akhil Gargey Iragavarapu, Gabriela May Sullivan, Frank R Moss, Adam Frost, Matteo Dal Peraro, Halil Aydin.

Cardiolipin is a mitochondria-specific phospholipid that forms heterotypic interactions with membrane-shaping proteins and regulates the dynamic remodeling and function of mitochondria. However, the precise mechanisms through which cardiolipin influences mitochondrial morphology are not well understood. In this study, employing molecular dynamics simulations, we determined that cardiolipin molecules extensively engage with the paddle domain of mitochondrial fusion protein OPA1, which controls membrane-shaping mechanisms. Structure-function analysis confirmed the interactions between cardiolipin and two conserved motifs of OPA1 at the membrane-binding sites. We further developed a bromine-labeled cardiolipin probe to enhance cryoEM contrast and characterized the structure of OPA1 assemblies bound to the cardiolipin brominated lipid bilayers. Our images provide direct evidence of cardiolipin enrichment within the OPA1-binding leaflet. Last, we observed a decrease in membrane remodeling activity for OPA1 in lipid compositions with increasing concentrations of monolyso-cardiolipin. This suggests that the partial replacement of cardiolipin by monolyso-cardiolipin, as observed in Barth syndrome, alters the malleability of the membrane and compromises proper remodeling. Together, these data provide insights into how biological membranes regulate the mechanisms governing mitochondrial homeostasis.

DOI: https://doi.org/10.1038/s41467-025-63813-4
Sci Rep. 2025 Sep 29. 15(1): 33572

Integrated multi omics and machine learning reveal mitochondrial immunometabolic networks in sepsis associated encephalopathy.

Zhenze Zhang, Xinliang Qiu, Xing Zeng, Xinhai Liu, Jiali Lu, Caixue Xu, Jing Huang, Caiqing Zhao, Yian Zhan.

  Sepsis-associated encephalopathy (SAE) is a major complication in intensive care units, characterized by diffuse brain dysfunction due to systemic inflammation. Despite advances in critical care medicine, SAE remains a key factor in poor patient outcomes, with its pathogenesis closely related to mitochondrial damage and the release of mitochondrial DNA (mtDNA). In this study, we integrated multiple transcriptomic and single-cell sequencing datasets to comprehensively analyze mitochondrial-associated differentially expressed genes (MitoDEGs) in SAE brain tissues. Using machine learning algorithms, we identified three core biomarkers (ALDH7A1, HOGA1, and AA467197). Functional enrichment analysis showed that the upregulated genes in SAE were mainly involved in immune and inflammatory responses, while the downregulated genes were associated with mitochondrial metabolism and vascular functions. Based on MitoDEGs, clinical subtype analysis shows that changes in mitochondrial function can effectively distinguish three sepsis subtypes (Cluster 1-3). Among these, Cluster 3 had worse prognosis due to enhanced mitochondrial function and activated inflammatory pathways. Immune microenvironment analysis revealed that MitoDEGs were closely associated with damage-associated molecular patterns (DAMPs) signaling and the expression of mitochondrial respiratory chain complexes. Experimental validation showed that exogenous mtDNA significantly increased the levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6), thereby aggravating brain tissue pathological damage.

Keywords:  Machine learning; Mitochondrial dysfunction; MtDNA; Multi-Omics; Sepsis-Associated encephalopathy (SAE)

DOI:  https://doi.org/10.1038/s41598-025-18650-2
Sci Adv. 2025 Oct 03. 11(40): eadw7376

The PP2A-B55α phosphatase is a master regulator of mitochondrial degradation and biogenesis.

Valentina Cianfanelli, Monica Nanni, Samantha Corrà, Sofia Mauri, David Sumpton, Sergio Lilla, Rossella De Cegli, Matteo Bordi, Giacomo Milletti, Caterina Ferraina, Arnaldur Hall, Michele Petraroia, Valentina Clausi, Ezio Giorda, Marco Scarsella, Alessandra Barbiera, Giulia Cadeddu, Marco Colasanti, Tiziana Persichini, Kenji Maeda, Apolinar Maya-Mendoza, Jiri Bartek, Chiara Di Malta, Franco Locatelli, Sara Zanivan, Shehab Ismail, Elena Ziviani, Francesco Cecconi.

Mitochondrial homeostasis relies on a tight balance between mitochondrial biogenesis and degradation. Although mitophagy is one of the main pathways involved in the clearance of damaged or old mitochondria, its coordination with mitochondrial biogenesis is poorly characterized. Here, by unbiased approaches including last-generation liquid chromatography coupled to mass spectrometry and transcriptomics, we identify the protein phosphatase PP2A-B55α/PPP2R2A as a Parkin-dependent regulator of mitochondrial number. Upon mitochondrial damage, PP2A-B55α determines the amplitude of mitophagy induction and execution by regulating both early and late mitophagy events. A few minutes after the insult, ULK1 is released from the inhibitory regulation of PP2A-B55α, whereas 2 to 4 hours later, PP2A-B55α promotes the nuclear translocation of TFEB, the master regulator of autophagy and lysosome genes, to support mitophagy execution. Moreover, PP2A-B55α controls a transcriptional program of mitochondrial biogenesis by stabilizing the Parkin substrate and PGC-1α inhibitor PARIS. PP2A-B55α targeting rescues neurodegenerative phenotypes in a fly model of Parkinson's disease, thus suggesting potential therapeutic application.

DOI: https://doi.org/10.1126/sciadv.adw7376
Trends Biochem Sci. 2025 Oct 02. pii: S0968-0004(25)00219-1. [Epub ahead of print]

Mitochondrial dynamics and pore formation in regulated cell death pathways.

Lisa Hohorst, Uris Ros, Ana J Garcia-Saez.

  Mitochondria act as central hubs for cell death signaling. During apoptosis and regulated necrosis (pyroptosis, necroptosis, and ferroptosis), mitochondria undergo drastic changes including membrane permeabilization, fragmentation, and loss of membrane potential. However, dissection of the mechanisms underlying these processes is challenging because they involve remodeling of mitochondrial membranes coupled to the assembly of protein complexes whose dynamics are difficult to capture. We discuss progress in our understanding of mitochondrial alterations in cell death and highlight state-of-the-art experimental approaches to study them. We focus on advanced single-molecule and correlative microscopy methods which have recently provided unprecedented details about the dynamics and structure of protein complexes in mitochondria and their impact on membrane organization.

Keywords:  apoptosis; correlative microscopy; mitochondria dynamics; mitochondrial outer membrane permeabilization (MOMP); pore formation; single-molecule microscopy

DOI:  https://doi.org/10.1016/j.tibs.2025.09.001
Antioxid Redox Signal. 2025 Sep 29.

Endothelial Gasdermin D Induces Mitochondrial Damage and Activates the STING Pathway in Lipopolysaccharide-Accelerated Atherosclerosis.

Xiaoyue Song, Junqiang Xue, Enyong Su, Shiyao Xie, Xuelin Cheng, Peng Yu, Lili Wei, Ming Liu, Hong Jiang.

  Aims: Chronic inflammation is a widely acknowledged contributor to the development of atherosclerosis. Gasdermin D (GSDMD) serves as a key executor of pyroptosis in inflammatory diseases. This study aims to determine the role of endothelial GSDMD in lipopolysaccharide (LPS)-accelerated atherosclerosis and elucidate its underlying molecular mechanisms. Results: GSDMD expression was aberrantly activated in both LPS-accelerated atherosclerotic animal models and oxidized low-density lipoprotein plus LPS-treated endothelial cell models. Compared with the control, endothelial GSDMD deficiency attenuated the atherogenesis progression and vascular endothelial inflammation induced by LPS and protected against the progression of mitochondrial damage, the release of mitochondrial ROS and mitochondrial DNA, and the activation of the stimulator of interferon genes (STING) pathway both in vivo and in vitro. Mechanistically, endothelial GSDMD expression mediates mitochondrial membrane permeabilization and mitochondrial damage-associated molecular patterns release and triggers the STING pathway to aggravate atherosclerotic progression. In addition, the STING pathway activation was proved to partially reverse the effects of endothelial GSDMD deficiency both in vivo and in vitro. Moreover, the signal transducer and activator of transcription 3 was identified as a positive regulator of GSDMD expression. Innovation and Conclusion: Our findings elucidate the mechanism by which endothelial GSDMD exerts its atherogenic effects by increasing mitochondrial damage and upregulating the STING pathway in LPS-accelerated atherosclerosis. GSDMD promises to be a critical therapeutic target for atherosclerotic cardiovascular diseases. Antioxid. Redox Signal. 00, 000-000.

Keywords:  GSDMD; STING pathway; atherosclerosis; endothelial cell; mitochondrial damage

DOI:  https://doi.org/10.1177/15230864251380286
Trends Biochem Sci. 2025 Oct 02. pii: S0968-0004(25)00222-1. [Epub ahead of print]

Interconnectivity of mitochondrial protein biogenesis and quality control.

Abi S Ghifari, Carmela Vazquez-Calvo, Andreas Carlström, Martin Ott.

  Mitochondrial protein homeostasis (proteostasis) keeps the mitochondrial proteome functional. Thus, proteostasis is essential for mitochondrial activity and overall cellular functions, and a reduction in its function corresponds with diseases and aging in humans. Recent studies in various model organisms highlight components and mechanisms of mitochondrial proteostasis from biogenesis, through assembly, to turnover. Key findings include the identification of new components and mechanistic insights into protein import and mitochondrial translation processes, the interconnectivity of protein biogenesis and quality control, and proteolytic degradation machineries. In this review we discuss these advances that improve our current understanding of the inner workings and significance of the mitochondrial proteostasis network in maintaining functional mitochondria.

Keywords:  mitochondria; proteases; protein import; proteolysis; proteostasis; translation

DOI:  https://doi.org/10.1016/j.tibs.2025.09.004
Front Cell Neurosci. 2025 ;19 1635775

Establishment of human Leber's hereditary optic neuropathy model using iPSC-derived retinal organoids.

Kota Aoshima, Yuya Takagi, Michinori Funato, Yoshiki Kuse, Shinsuke Nakamura, Masamitsu Shimazawa.

  Leber's hereditary optic neuropathy (LHON) is a mitochondrial disease caused by mitochondrial DNA mutations, leading to central vision loss and retinal ganglion cell (RGC) degeneration. Progress in understanding LHON and developing treatments has been limited by the lack of human-like models. In this study, we aimed to establish a human retinal model of LHON using retinal organoids (ROs) from LHON patient-derived induced pluripotent stem cells (LHON-iPSCs). We first confirmed LHON-iPSCs were successfully differentiated into ROs (LHON-ROs). LHON-RO showed a reduction in RGC numbers and the density of neural axons. Additionally, both mitochondrial membrane potential and ATP production were decreased in LHON-RO. Finally, treatment with idebenone, the only approved therapeutic agent for LHON, improved RGC numbers in LHON-RO. This model replicates key clinical features of LHON, including RGC and axonal loss, and demonstrates idebenone's therapeutic potential. Furthermore, a comprehensive analysis of the LHON-RO model revealed impaired mitophagy, suggesting novel therapeutic targets for LHON. Thus, the LHON-RO model offers a valuable platform for studying LHON pathogenesis and evaluating treatments.

Keywords:  Leber’s hereditary optic neuropathy; in vitro disease modeling; mitochondrial disease; mitophagy; retinal organoid

DOI:  https://doi.org/10.3389/fncel.2025.1635775
Proc Natl Acad Sci U S A. 2025 Oct 07. 122(40): e2506761122

A mouse model of MEPAN demonstrates a role for mitochondrial fatty acid synthesis in iron-sulfur cluster and supercomplex formation.

Deborah G Murdock, Kevin A Janssen, Kierstin Keller, Katherine L Mitchell, Maina Beauplan, William T O'Brien, Lia D'Alessandro, Jeffrey A Haltom, Douglas C Wallace.

  MEPAN (Mitochondrial Enoyl CoA Reductase Protein-Associated Neurodegeneration) is an early-onset movement disorder characterized by ataxia, dysarthria, and optic atrophy. Here, we report the creation of a mouse model of MEPAN with patient-similar compound heterozygous mutations in the Mecr gene. The MEPAN mouse recapitulates the major hallmarks of MEPAN, including a movement disorder, optic neuropathy, defects in protein lipoylation, and reduced mitochondrial oxidative phosphorylation in the brain. MECR catalyzes the last step in mitochondrial fatty acid synthesis (mtFASII), and the mechanism by which loss of mtFASII leads to neurological disease is unknown. LC-MS/MS-based proteomic analysis of Mecr mutant cerebella identified loss of subunits of complex I of oxidative phosphorylation (OXPHOS) and subunits of the iron-sulfur cluster assembly (ISC) complex. Native gels revealed altered OXPHOS complex and supercomplex formation and changes in binding of the acyl carrier protein (ACP) to mitochondrial complexes. These results demonstrate that MECR plays a key role in the acylation of ACP which is necessary for ACP-LYRM-mediated supercomplex modulation and ISC biogenesis and suggest unique pathways for therapeutics.

Keywords:  genetics; iron; mitochondrial disease; mitochondrial fatty acid synthesis; mouse model

DOI:  https://doi.org/10.1073/pnas.2506761122
Sci Rep. 2025 Sep 30. 15(1): 33959

Proteomic analysis of brain and spinal cord tissue reveals distinct immune and mitochondrial processes between human and mouse ALS models.

Alanna G Spiteri, Joel R Steele, Han-Chung Lee, Haijian Zhang, Jiaqi Sun, Ralf B Schittenhelm, Chien-Hsiung Yu, Catriona McLean, Colin L Masters, Benjamin Goudey, Liang Jin, Yijun Pan.

  Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease resulting in the progressive loss of motor neurons in the brain and spine. More than 95% of cases are pathologically characterized by the cytoplasmic accumulation of hyperphosphorylated and ubiquitinated transactive response DNA-binding protein 43 (TDP-43). Multiple mouse models with TDP-43 accumulation have been developed, however, whether they recapitulate molecular features of ALS pathology is unclear. Given the lack of curative treatment for ALS, there is an urgent need to identify the precise biological processes contributing to disease pathogenesis for the development of effective therapeutic treatments. Thus, in this study we employed label-based untargeted proteomics to characterize the ALS proteome and related biological processes in the spinal cord and brain of TDP-43Q331K mice, a transgenic mouse model of ALS and the motor cortex and the cervical, thoracic, and lumbar spinal cord regions from humans. In humans, we observed highly overlapping responses across the four tissues examined, primarily related to the upregulation of immune processes and the downregulation of mitochondrial function. In contrast, TDP-43Q331K mice demonstrate a lack of enrichment for immune activation and the opposite regulation of mitochondrial processes. A meta-analysis of previously published mouse datasets identified the Ubqln2 knock-out mouse model as showing stronger parallels with our late-stage human ALS. Overall, this study provides in-depth analysis of the site-specific dysregulated proteomes and their associated functional processes across species. Thereby, identifying potential therapeutic targets while emphasizing the limitations of specific mouse models at certain timepoints in recapitulating ALS-related processes for future model development.

Keywords:  Amyotrophic lateral sclerosis; Immune-mediated pathology; Mitochondrial dysfunction; Motor neurone disease; Neurodegeneration; TMT-proteomics

DOI:  https://doi.org/10.1038/s41598-025-11466-0
Proc Natl Acad Sci U S A. 2025 Oct 07. 122(40): e2502841122

Mitochondrial ROS triggers mitophagy through activating the DNA damage response signaling pathway.

Qi-Qiang Guo, Shan-Shan Wang, Xiao-You Jiang, Xiao-Chen Xie, Yu Zou, Jing-Wei Liu, Yang Guo, Yu-Han Li, Xi-Yan Liu, Shuang Hao, Xin-Yue Zhang, Xiao-Xu Wu, Song-Ming Lu, Hong-De Xu, Wen-Dong Guo, Yan-Ling Feng, Chuan-Gui Wang, Sheng-Ping Zhang, Jia-Bin Li, Chen Liu, Xiao-Yu Song, Toren Finkel, Liu Cao.

  The homeostatic link between the production of mitochondrial ROS (mtROS) and mitophagy plays a significant role in how cells respond to various physiological and pathological conditions. However, it remains unclear how cells translate oxidative stress signals into adaptive mitophagy responses. Here, we show that mtROS act as signaling molecules that activate the ataxia-telangiectasia mutated (ATM)-cell cycle checkpoint kinase 2 (CHK2), a DNA damage response (DDR) pathway. When activated, CHK2 regulates three critical steps in mitophagy. First, CHK2 phosphorylates mitochondrial membrane protein ATAD3A at Ser371, which inhibits the transport of PINK1 to the inner mitochondrial membrane and leads to the accumulation of PINK1 and the commencement of mitophagy. Second, activated CHK2 targets the autophagy adaptor OPTN at Ser177 and Ser473, thereby enhancing the targeting of ubiquitinated mitochondria to autophagosomes. Finally, CHK2 phosphorylates Beclin 1 at Ser90 and Ser93, hence promoting the formation of autophagosomal membranes. Consistent with these effects, Chk2-/- mice show impaired mitophagic induction and impaired recovery in a ROS-dependent model of renal ischemia-reperfusion. Our study reveals a mtROS-triggered adaptive pathway that coordinates mitophagic induction, in order to protect cells and tissues exposed to pathophysiological stress-induced damage.

Keywords:  ATM; CHK2; PINK1; mitophagy; mtROS

DOI:  https://doi.org/10.1073/pnas.2502841122
J Appl Biomed. 2025 Sep;23(3): 97-106

Elevated plasma levels of cell-free mtDNA are associated with acute rejection following heart transplantation.

Dana Dlouha, Kristyna Janouskova, Sarka Chytilova, Jevgenija Vymetalova, Marianna Lukasova, Sarka Novakova, Eva Rohlova, Jaroslav A Hubacek.

  Acute rejection (AR) following heart transplantation (HTx) is a common complication, especially in the early post-HTx period. Mitochondrial DNA (mtDNA), released into circulation from stressed mitochondria, mimics ongoing immune activation and facilitates the release of pro-inflammatory substances. Our study aimed to assess cell-free mtDNA levels to identify early indicators of acute rejection progression. The absolute concentration of cf-mtDNA (cp/μl) was measured in 77 adult patients using quantitative polymerase chain reaction. Blood samples (n = 300) were collected before their corresponding biopsy according to the timeline within the first year post-HTx. The median cf-mtDNA levels in samples with confirmed AR (n = 57) was higher compared to samples without diagnosed rejection (n = 210; Padj < 0.01). When acute cellular (ACR; n = 39) and antibody-mediated rejection (AMR; n = 18) were analyzed separately, only AMR demonstrated higher levels compared to samples without diagnosed rejection (Padj = 0.02). The highest cf-mtDNA levels were detected in samples collected during early post-HTx complications compared to samples without rejection and AR samples (for both Padj < 0.0001). Both ACR and AMR were observed throughout the one-year period, with the majority (3rd quartile) occurring during the first 200 days post-HTx. Post-HTx complications, such as graft dysfunction or acute kidney injury, were observed within the first 11 days, with the majority (71.4%) occurring within 5 days post-HTx. The presence of AR, and specifically AMR, is associated with elevated levels of cf-mtDNA. The increase in plasma cf-mtDNA levels strongly reflects the occurrence of early complications following HTx.

Keywords:  Biomarker; Rejection; Transplantation; cf-mtDNA

DOI:  https://doi.org/10.32725/jab.2025.014
Am J Physiol Endocrinol Metab. 2025 Oct 03.

Diabetic heart shows preferential secretion of inner mitochondrial membrane proteins in the presence of mitochondrial oxidative stress.

Paula M Miotto, Jacqueline Bayliss, Gio Fidelito, James R Bell, Lea M D Delbridge, Matthew J Watt, Magdalene K Montgomery.

  Heart disease, including diabetic cardiomyopathy, is a leading cause of mortality in patients with type 2 diabetes (T2D). Defects in heart function are accompanied by marked changes in cardiac metabolism, including dysregulation of lipid and glucose metabolism, mitochondrial dysfunction, and oxidative stress. In addition to these metabolic defects, the heart is an important endocrine organ. However, while T2D has been shown to impact the secretome of liver, skeletal muscle and adipose tissue (among others), little is known about the secretome of the heart, and the influence of T2D on cardiac protein secretion. Using precision-cut heart slices from mice with insulin resistance (20-weeks of high-fat feeding) and T2D (db/db mice) compared to their respective controls, we performed mass spectrometry proteomics analysis of cardiac protein secretion as well as proteins contained within extracellular vesicles (EV). We reveal striking remodelling of cardiac protein secretion in T2D but not diet-induced insulin resistance. Specifically, we show a marked increase in the secretion of inner mitochondrial membrane (IMM) proteins in T2D, which was accompanied by a disproportional accumulation of outer mitochondrial membrane proteins within the heart. This was associated with increased mitochondrial oxidative stress, selective oxidative damage to IMM proteins, and reduced markers of LC3-mediated mitophagy in the db/db heart, highlighting secretion of mitochondrial components as a potential alternative pathway for mitochondrial quality control. Altogether, this study provides an in-depth proteomics analysis showing remodelling of cardiac protein secretion in T2D and provides insights into a possible link between mitochondrial oxidative stress and the release of mitochondrial components.

Keywords:  cardiokine; diabetic heart; endocrine; mitochondrial dysfunction; oxidative stress

DOI:  https://doi.org/10.1152/ajpendo.00073.2025
Sci Rep. 2025 Sep 29. 15(1): 33686

The role and mechanism of transcription factor KLF4 in regulating mitochondrial damage and apoptosis by activating chondrocyte autophagy in osteoarthritis.

Wenguang Feng, Haibin Wang, Guoliang Zhang, Wang Gao, Hongcang Li, Haibo Liu, Yanhong Sun.

   OBJECTIVE: To explore the role and mechanism of transcription factor KLF4 in regulating mitochondrial damage and apoptosis by activating chondrocyte autophagy. Human primary chondrocytes were treated with IL-1β to establish an in vitro osteoarthritis model. KLF4 was overexpressed using lentivirus to intervene in chondrocytes. Cell apoptosis and mitochondrial membrane potential were detected by flow cytometry. Mitochondrial morphology was observed under transmission electron microscopy. Cell ATP level was detected by ELISA. Ca2 + homeostasis was detected by flow cytometry with Fluo-3/AM fluorescence labeling. The expression of autophagy-related proteins Beclin1, P62, and LC3 was detected by WB. The interaction between transcription factor KLF4 and gene p62 promoter was verified by dual luciferase assay. The interaction between p62, Beclin1 and KLF4 was verified by Chip assay. To further explore the relationship between KLF4 and autophagy, KLF4 was overexpressed and treated with autophagy inhibitor 3-MA (5mmol/L). The expression of autophagy-related proteins Beclin1, P62, and LC3 was detected by WB. Cell apoptosis level was detected by flow cytometry. The mitochondrial membrane potential level was detected by flow cytometry. Ca2 + homeostasis was detected by flow cytometry with Fluo-3/AM fluorescence labeling. In chondrocytes treated with IL-1β, TNF-α levels increased significantly, apoptosis rate rose, and ATP generation declined. However, after overexpression of KLF4, apoptosis level decreased significantly; ATP level increased significantly, and mitochondrial structure and function gradually recovered. Flow cytometry detection of mitochondrial membrane potential showed a significant decrease after KLF4 overexpression, and Ca2 + homeostasis was partially restored. WB detection of autophagy-related proteins showed a significant increase in p62 and cellular autophagy levels. Dual luciferase results indicated that transcription factor KLF4 interacted with the promoter of gene p62; Chip experiment results suggested that KLF4 may interact with the promoter regions of P62 and Beclin1. After KLF4 overexpression combined with 3-MA treatment, compared with empty load combined with 3-MA, p62 and LC3 protein expression increased significantly, apoptosis level decreased significantly, and membrane potential level decreased. Transcription factor KLF4 can regulate mitochondrial damage and apoptosis by activating chondrocyte autophagy.

Keywords:  Autophagy; Chondrocytes; KLF4; Osteoarthritis; P62

DOI:  https://doi.org/10.1038/s41598-025-18720-5
ACS Cent Sci. 2025 Sep 24. 11(9): 1700-1714

Illuminating Mitochondrial Dynamics: Ultrahigh Labeling Stability Probe for Long-Term SIM Super-Resolution Imaging of Mitochondria.

Xiangpeng Lin, Xuelei Pang, Yue Huang, Xinxin Duan, Yunfei Wei, Ning Jing, Meng Zhang, Yu-Hui Zhang.

Delineating intricate mitochondrial dynamic changes over extended time scales through combined fluorescent probes and super-resolution microscopy is pivotal for deciphering the pathogenesis of mitochondrial-related diseases. However, a major challenge lies in the scarcity of probes that simultaneously exhibit robust labeling stability, exceptional photostability, and minimal cytotoxicity. Herein, rational design and screening yielded a novel covalent mitochondrial probe, HZ Mito Red. Due to its exceptional covalent labeling efficiency, HZ Mito Red exhibits superior mitochondrial labeling stability, with a 10-fold improvement compared to Mito Tracker Red (MTR). Furthermore, it exhibits remarkable photostability, retaining over 80% fluorescence after 300 SIM images, and negligible phototoxicity, preserving mitochondrial integrity even after 400 SIM images of continuous imaging. These advantageous properties facilitated the pioneering of high signal-to-noise, long-term dynamic SIM super-resolution imaging of mitochondria during ferroptosis, apoptosis, and autophagy, achieving unprecedented detailed delineation of mitochondrial morphology. Additionally, engineered for multichannel mitochondrial imaging, HZ Mito Deep Red mirrors the exceptional labeling stability of HZ Mito Red, achieving near-phototoxicity-free dynamic tracking with 60% fluorescence retention after 300 SIM images. Significantly, both HZ Mito Red and HZ Mito Deep Red are compatible with cell immunofluorescence staining. This study provides a robust and versatile tool for the in-depth analysis of mitochondrial dynamics in disease states.

DOI: https://doi.org/10.1021/acscentsci.5c00695