New insights into the relationship of mitochondrial metabolism and atherosclerosis

Chen X., Yang Y., Zhou Z., Yu H., Zhang S., Huang S., Wei Z., Ren K., Jin Y.

Cardiovascular diseases (CVDs) represent a significant public health concern because of their associations with inflammation, oxidative stress, and abnormal remodeling of the heart and blood vessels. In this review, we discuss the intricate interplay between mitochondria-associated membranes (MAMs) and cardiovascular inflammation, highlighting their role in key cellular processes such as calcium homeostasis, lipid metabolism, oxidative stress management, and ERS. We explored how these functions impact the pathogenesis and progression of various CVDs, including myocardial ischemia-reperfusion injury, atherosclerosis, diabetic cardiomyopathy, cardiovascular aging, heart failure, and pulmonary hypertension. Additionally, we examined current therapeutic strategies targeting MAM-related pathways and proteins, emphasizing the potential of MAMs as therapeutic targets. Our review aims to provide new insights into the mechanisms of cardiovascular inflammation and propose novel therapeutic approaches to improve cardiovascular health outcomes.

Cui J., Chen Y., Yang Q., Zhao P., Yang M., Wang X., Mang G., Yan X., Wang D., Tong Z., Wang P., Wang N., Liu M., Zhang M., Yu B.

Abstract Background Doxorubicin (DOX) is a breakthrough drug in cancer therapy that mediates irreversible dosedependent cardiotoxicity with poor outcomes.Cardiomyocyte ferroptosis plays a pivotal role in the progression of DOX-induced cardiomyopathy (DIC). Agents that block DOX-induced cardiomyocyte ferroptosis may have clinical utility in the treatment of DIC. Purpose We pursued the potential role of protosappanin A (PrA), an active constituent extract from traditional Chinese hematoxylin, on DOX-induced cardiac dysfunction. Methods We established acute DIC murine models to investigate the role of PrA in DOX-induced cardiotoxicity.In vivo, western blotting was performed to assess the levels of classical proteins associated with the iron death pathway, while Prussian blue staining and DHE staining were utilized to measure iron ion levels and reactive oxygen species respectively. In vitro, DOX-induced H9C2 cells model was established and the level of ferroptosis-related indicators were detected,such as iron, reactive oxygen species (ROS), and lipid peroxides. Proteome microarray, Molecular docking and Cellular thermal shift assay were used to identify the molecular targets (ACSL4 and FTH1) of PrA. Pull-down assay was used to validate the interaction of PrA with ACSL4 and FTH1 proteins in lysates from H9c2 cells, and explored theirs possible mechanism of action. Finally, we investigated the in vivo effect of PrA treatment in mice challenged with a myocardial ischemia-reperfusion mouse model. Results We report for the first time that PrA ameliorates myocardial damage and cardiac dysfunction in a mouse model of DIC. PrA improves DOX-induced ferroptotic phenotypes in cardiomyocytes, as demonstrated by reduced production of iron, reactive oxygen species (ROS), and lipid peroxides, thereby preserving mitochondrial homeostasis. PrA physically combines with the ferroptosis-related protein acyl-CoA synthetase long-chain family member 4 (ACSL4) and ferritin heavy chain 1 (FTH1), thus conferring the following regulatory mechanisms: PrA inhibits ACSL4 phosphorylation and subsequent phospholipid peroxidation; PrA prevents FTH1 autophagic degradation and subsequent ferrous ions (Fe2+) release. Notably, the cardioprotective and antiferroptotic activities of PrA are verified in a myocardial ischemiareperfusion mouse model. Conclusion Our studies indicate for the first time that PrA has a superior protective effect against DOX-induced cardiotoxicity via inhibiting a dual ferroptosis-assistance mechanism of the ACSL4/FTH1-dependent axis. We unveil a novel pharmacological inhibitor that targets ferroptosis, highlighting additional therapeutic options for chemodrug-induced cardiotoxicity and ferroptosis-triggered disorders.

Zheng X., Qiu J., Ye J., Gong Y., Jiang T., Gao N., Jiang C., Chu B., Zhang W., Li Z., Wu X., Yang G., Feng X., Hong Z.

Intervertebral Disc Degeneration (IVDD) is one of the leading causes of low back pain, significantly impacting both individuals and society. This study aimed to investigate the significance of macrophage infiltration and the role of macrophage-secreted platelet-derived growth factor-BB (PDGF-BB) in IVDD progression.

Prashar A., Bussi C., Fearns A., Capurro M.I., Gao X., Sesaki H., Gutierrez M.G., Jones N.L.

Mitochondrial membranes define distinct structural and functional compartments. Cristae of the inner mitochondrial membrane (IMM) function as independent bioenergetic units that undergo rapid and transient remodelling, but the significance of this compartmentalized organization is unknown1. Using super-resolution microscopy, here we show that cytosolic IMM vesicles, devoid of outer mitochondrial membrane or mitochondrial matrix, are formed during resting state. These vesicles derived from the IMM (VDIMs) are formed by IMM herniation through pores formed by voltage-dependent anion channel 1 in the outer mitochondrial membrane. Live-cell imaging showed that lysosomes in proximity to mitochondria engulfed the herniating IMM and, aided by the endosomal sorting complex required for transport machinery, led to the formation of VDIMs in a microautophagy-like process, sparing the remainder of the organelle. VDIM formation was enhanced in mitochondria undergoing oxidative stress, suggesting their potential role in maintenance of mitochondrial function. Furthermore, the formation of VDIMs required calcium release by the reactive oxygen species-activated, lysosomal calcium channel, transient receptor potential mucolipin 1, showing an interorganelle communication pathway for maintenance of mitochondrial homeostasis. Thus, IMM compartmentalization could allow for the selective removal of damaged IMM sections via VDIMs, which should protect mitochondria from localized injury. Our findings show a new pathway of intramitochondrial quality control. We show that cytosolic inner mitochondrial membrane vesicles, devoid of outer mitochondrial membrane or mitochondrial matrix, are formed during resting state and directly herniate into lysosomes through pores formed by voltage-dependent anion channel 1 in the outer mitochondrial membrane, thereby allowing their selective removal.

Liang F.G., Zandkarimi F., Lee J., Axelrod J.L., Pekson R., Yoon Y., Stockwell B.R., Kitsis R.N.

Ferroptosis, an iron-dependent form of nonapoptotic cell death mediated by lipid peroxidation, has been implicated in the pathogenesis of multiple diseases. Subcellular organelles play pivotal roles in the regulation of ferroptosis, but the mechanisms underlying the contributions of the mitochondria remain poorly defined. Optic atrophy 1 (OPA1) is a mitochondrial dynamin-like GTPase that controls mitochondrial morphogenesis, fusion, and energetics. Here, we report that human and mouse cells lacking OPA1 are markedly resistant to ferroptosis. Reconstitution with OPA1 mutants demonstrates that ferroptosis sensitization requires the GTPase activity but is independent of OPA1-mediated mitochondrial fusion. Mechanistically, OPA1 confers susceptibility to ferroptosis by maintaining mitochondrial homeostasis and function, which contributes both to the generation of mitochondrial lipid reactive oxygen species (ROS) and suppression of an ATF4-mediated integrated stress response. Together, these results identify an OPA1-controlled mitochondrial axis of ferroptosis regulation and provide mechanistic insights for therapeutically manipulating this form of cell death in diseases.

Zhang H., Tsui C.K., Garcia G., Joe L.K., Wu H., Maruichi A., Fan W., Pandovski S., Yoon P.H., Webster B.M., Durieux J., Frankino P.A., Higuchi-Sanabria R., Dillin A.

Cellular homeostasis is intricately influenced by stimuli from the microenvironment, including signaling molecules, metabolites, and pathogens. Functioning as a signaling hub within the cell, mitochondria integrate information from various intracellular compartments to regulate cellular signaling and metabolism. Multiple studies have shown that mitochondria may respond to various extracellular signaling events. However, it is less clear how changes in the extracellular matrix (ECM) can impact mitochondrial homeostasis to regulate animal physiology. We find that ECM remodeling alters mitochondrial homeostasis in an evolutionarily conserved manner. Mechanistically, ECM remodeling triggers a TGF-β response to induce mitochondrial fission and the unfolded protein response of the mitochondria (UPR

Tábara L.C., Burr S.P., Frison M., Chowdhury S.R., Paupe V., Nie Y., Johnson M., Villar-Azpillaga J., Viegas F., Segawa M., Anand H., Petkevicius K., Chinnery P.F., Prudent J.

Mitochondrial dynamics play a critical role in cell fate decisions and in controlling mtDNA levels and distribution. However, the molecular mechanisms linking mitochondrial membrane remodeling and quality control to mtDNA copy number (CN) regulation remain elusive. Here, we demonstrate that the inner mitochondrial membrane (IMM) protein mitochondrial fission process 1 (MTFP1) negatively regulates IMM fusion. Moreover, manipulation of mitochondrial fusion through the regulation of MTFP1 levels results in mtDNA CN modulation. Mechanistically, we found that MTFP1 inhibits mitochondrial fusion to isolate and exclude damaged IMM subdomains from the rest of the network. Subsequently, peripheral fission ensures their segregation into small MTFP1-enriched mitochondria (SMEM) that are targeted for degradation in an autophagic-dependent manner. Remarkably, MTFP1-dependent IMM quality control is essential for basal nucleoid recycling and therefore to maintain adequate mtDNA levels within the cell.

Liu L., Wu Y., Liu K., Zhu M., Guang S., Wang F., Liu X., Yao X., He J., Fu C.

Ribosomes mediate protein synthesis, which is one of the most energy-demanding activities within the cell, and mitochondria are one of the main sources generating energy. How mitochondrial morphology and functions are adjusted to cope with ribosomal defects, which can impair protein synthesis and affect cell viability, is poorly understood. Here, we used the fission yeast Schizosaccharomyces Pombe as a model organism to investigate the interplay between ribosome and mitochondria. We found that a ribosomal insult, caused by the absence of Rpl2702, activates a signaling pathway involving Sty1/MAPK and mTOR to modulate mitochondrial morphology and functions. Specifically, we demonstrated that Sty1/MAPK induces mitochondrial fragmentation in a mTOR-independent manner while both Sty1/MAPK and mTOR increases the levels of mitochondrial membrane potential and mitochondrial reactive oxygen species (mROS). Moreover, we demonstrated that Sty1/MAPK acts upstream of Tor1/TORC2 and Tor1/TORC2 and is required to activate Tor2/TORC1. The enhancements of mitochondrial membrane potential and mROS function to promote proliferation of cells bearing ribosomal defects. Hence, our study reveals a previously uncharacterized Sty1/MAPK-mTOR signaling axis that regulates mitochondrial morphology and functions in response to ribosomal insults and provides new insights into the molecular and physiological adaptations of cells to impaired protein synthesis.

Zhao L., Zou X., Deng J., Sun B., Li Y., Zhao L., Zhao H., Zhang X., Yuan X., Zhao X., Zou F.

Mitochondrial homeostasis is coordinated through communication between mitochondria and the nucleus. In response to stress, mitochondria generate retrograde signals to protect against their dysfunction by activating the expression of nuclear genes involved in metabolic reprogramming. However, the mediators associated with mitochondria-to-nucleus communication pathways remain to be clarified. Here, we identified that hnRNPH1 functions as a pivotal mediator of mitochondrial retrograde signaling to maintain mitochondrial homeostasis. hnRNPH1 accumulates in the nucleus following mitochondrial stress in a 5′-adenosine monophosphate-activated protein kinase (AMPK)-dependent manner. Accordingly, hnRNPH1 interacts with the transcription factor NRF1 and binds to the DRP1 promoter, enhancing the transcription of DRP1. Furthermore, in the cytoplasm, hnRNPH1 directly interacts with DRP1 and enhances DRP1 Ser616 phosphorylation, thereby increasing DRP1 translocation to mitochondrial outer membranes and triggering mitochondrial fission. Collectively, our findings reveal a novel role for hnRNPH1 in the mitochondrial-nuclear communication pathway to maintain mitochondrial homeostasis under stress and suggest that it may be a potential target for mitochondrial dysfunction diseases.

Trumpff C., Monzel A.S., Sandi C., Menon V., Klein H., Fujita M., Lee A., Petyuk V.A., Hurst C., Duong D.M., Seyfried N.T., Wingo A.P., Wingo T.S., Wang Y., Thambisetty M., et. al.

Psychosocial experiences affect brain health and aging trajectories, but the molecular pathways underlying these associations remain unclear. Normal brain function relies on energy transformation by mitochondria oxidative phosphorylation (OxPhos). Two main lines of evidence position mitochondria both as targets and drivers of psychosocial experiences. On the one hand, chronic stress exposure and mood states may alter multiple aspects of mitochondrial biology; on the other hand, functional variations in mitochondrial OxPhos capacity may alter social behavior, stress reactivity, and mood. But are psychosocial exposures and subjective experiences linked to mitochondrial biology in the human brain? By combining longitudinal antemortem assessments of psychosocial factors with postmortem brain (dorsolateral prefrontal cortex) proteomics in older adults, we find that higher well-being is linked to greater abundance of the mitochondrial OxPhos machinery, whereas higher negative mood is linked to lower OxPhos protein content. Combined, positive and negative psychosocial factors explained 18 to 25% of the variance in the abundance of OxPhos complex I, the primary biochemical entry point that energizes brain mitochondria. Moreover, interrogating mitochondrial psychobiological associations in specific neuronal and nonneuronal brain cells with single-nucleus RNA sequencing (RNA-seq) revealed strong cell-type-specific associations for positive psychosocial experiences and mitochondria in glia but opposite associations in neurons. As a result, these “mind-mitochondria” associations were masked in bulk RNA-seq, highlighting the likely underestimation of true psychobiological effect sizes in bulk brain tissues. Thus, self-reported psychosocial experiences are linked to human brain mitochondrial phenotypes.

Pan H., Ho S.E., Xue C., Cui J., Johanson Q.S., Sachs N., Ross L.S., Li F., Solomon R.A., Connolly E.S., Patel V.I., Maegdefessel L., Zhang H., Reilly M.P.

BACKGROUND: Atherosclerosis, a leading cause of cardiovascular disease, involves the pathological activation of various cell types, including immunocytes (eg, macrophages and T cells), smooth muscle cells (SMCs), and endothelial cells. Accumulating evidence suggests that transition of SMCs to other cell types, known as phenotypic switching, plays a central role in atherosclerosis development and complications. However, the characteristics of SMC-derived cells and the underlying mechanisms of SMC transition in disease pathogenesis remain poorly understood. Our objective is to characterize tumor cell–like behaviors of SMC-derived cells in atherosclerosis, with the ultimate goal of developing interventions targeting SMC transition for the prevention and treatment of atherosclerosis. METHODS: We used SMC lineage tracing mice and human tissues and applied a range of methods, including molecular, cellular, histological, computational, human genetics, and pharmacological approaches, to investigate the features of SMC-derived cells in atherosclerosis. RESULTS: SMC-derived cells in mouse and human atherosclerosis exhibit multiple tumor cell–like characteristics, including genomic instability, evasion of senescence, hyperproliferation, resistance to cell death, invasiveness, and activation of comprehensive cancer-associated gene regulatory networks. Specific expression of the oncogenic mutant Kras G12D in SMCs accelerates phenotypic switching and exacerbates atherosclerosis. Furthermore, we provide proof of concept that niraparib, an anticancer drug targeting DNA damage repair, attenuates atherosclerosis progression and induces regression of lesions in advanced disease in mouse models. CONCLUSIONS: Our findings demonstrate that atherosclerosis is an SMC-driven tumor-like disease, advancing our understanding of its pathogenesis and opening prospects for innovative precision molecular strategies aimed at preventing and treating atherosclerotic cardiovascular disease.

Fan X., Han J., Zhong L., Zheng W., Shao R., Zhang Y., Shi S., Lin S., Huang Z., Huang W., Cai X., Ye B.

BACKGROUND: Macrophages play a crucial role in atherosclerotic plaque formation, and the death of macrophages is a vital factor in determining the fate of atherosclerosis. GSDMD (gasdermin D)-mediated pyroptosis is a programmed cell death, characterized by membrane pore formation and inflammatory factor release. METHODS: ApoE −/− and Gsdmd −/− ApoE −/− mice, bone marrow transplantation, and AAV-F4/80-shGSDMD were used to examine the effect of macrophage-derived GSDMD on atherosclerosis. Single-cell RNA sequencing was used to investigate the changing profile of different cellular components and the cellular localization of GSDMD during atherosclerosis. RESULTS: First, we found that GSDMD is activated in human and mouse atherosclerotic plaques and Gsdmd −/− attenuates the atherosclerotic lesion area in high-fat diet–fed ApoE −/− mice. We performed single-cell RNA sequencing of ApoE −/− and Gsdmd −/− ApoE −/− mouse aortas and showed that GSDMD is principally expressed in atherosclerotic macrophages. Using bone marrow transplantation and AAV-F4/80-shGSDMD, we identified the potential role of macrophage-derived GSDMD in aortic pyroptosis and atherosclerotic injuries in vivo. Mechanistically, GSDMD contributes to mitochondrial perforation and mitochondrial DNA leakage and subsequently activates the STING (stimulator of interferon gene)-IRF3 (interferon regulatory factor 3)/NF-κB (nuclear factor kappa B) axis. Meanwhile, GSDMD regulates the STING pathway activation and macrophage migration via cytokine secretion. Inhibition of GSDMD with GSDMD-specific inhibitor GI-Y1 can effectively alleviate the progression of atherosclerosis. CONCLUSIONS: Our study has provided a novel macrophage-derived GSDMD mechanism in the promotion of atherosclerosis and demonstrated that GSDMD can be a potential therapeutic target for atherosclerosis.

Teixeira P., Galland R., Chevrollier A.

Mitochondria are complex organelles with an outer membrane enveloping a second inner membrane that creates a vast matrix space partitioned by pockets or cristae that join the peripheral inner membrane with several thin junctions. Several micrometres long, mitochondria are generally close to 300 nm in diameter, with membrane layers separated by a few tens of nanometres. Ultrastructural data from electron microscopy revealed the structure of these mitochondria, while conventional optical microscopy revealed their extraordinary dynamics through fusion, fission, and migration processes but its limited resolution power restricted the possibility to go further. By overcoming the limits of light diffraction, Super-Resolution Microscopy (SRM) now offers the potential to establish the links between the ultrastructure and remodelling of mitochondrial membranes, leading to major advances in our understanding of mitochondria's structure-function. Here we review the contributions of SRM imaging to our understanding of the relationship between mitochondrial structure and function. What are the hopes for these new imaging approaches which are particularly important for mitochondrial pathologies?

Zheng W., Chai P., Zhu J., Zhang K.

AbstractMitochondria play a pivotal part in ATP energy production through oxidative phosphorylation, which occurs within the inner membrane through a series of respiratory complexes1–4. Despite extensive in vitro structural studies, determining the atomic details of their molecular mechanisms in physiological states remains a major challenge, primarily because of loss of the native environment during purification. Here we directly image porcine mitochondria using an in situ cryo-electron microscopy approach. This enables us to determine the structures of various high-order assemblies of respiratory supercomplexes in their native states. We identify four main supercomplex organizations: I1III2IV1, I1III2IV2, I2III2IV2 and I2III4IV2, which potentially expand into higher-order arrays on the inner membranes. These diverse supercomplexes are largely formed by ‘protein–lipids–protein’ interactions, which in turn have a substantial impact on the local geometry of the surrounding membranes. Our in situ structures also capture numerous reactive intermediates within these respiratory supercomplexes, shedding light on the dynamic processes of the ubiquinone/ubiquinol exchange mechanism in complex I and the Q-cycle in complex III. Structural comparison of supercomplexes from mitochondria treated under different conditions indicates a possible correlation between conformational states of complexes I and III, probably in response to environmental changes. By preserving the native membrane environment, our approach enables structural studies of mitochondrial respiratory supercomplexes in reaction at high resolution across multiple scales, from atomic-level details to the broader subcellular context.

Liu H., Zhen C., Xie J., Luo Z., Zeng L., Zhao G., Lu S., Zhuang H., Fan H., Li X., Liu Z., Lin S., Jiang H., Chen Y., Cheng J., et. al.

When cells are stressed, DNA from energy-producing mitochondria can leak out and drive inflammatory immune responses if not cleared. Cells employ a quality control system called autophagy to specifically degrade damaged components. We discovered that mitochondrial transcription factor A (TFAM)—a protein that binds mitochondrial DNA (mtDNA)—helps to eliminate leaked mtDNA by interacting with the autophagy protein LC3 through an autolysosomal pathway (we term this nucleoid-phagy). TFAM contains a molecular zip code called the LC3 interacting region (LIR) motif that enables this binding. Although mutating TFAM’s LIR motif did not affect its normal mitochondrial functions, more mtDNA accumulated in the cell cytoplasm, activating inflammatory signalling pathways. Thus, TFAM mediates autophagic removal of leaked mtDNA to restrict inflammation. Identifying this mechanism advances understanding of how cells exploit autophagy machinery to selectively target and degrade inflammatory mtDNA. These findings could inform research on diseases involving mitochondrial damage and inflammation. Liu, Zhen, Xie, Luo, Zeng, Zhao et al. show that the major nucleoid protein TFAM interacts with cytoplasmic LC3B during oxidative or inflammatory stress to attenuate mitochondrial DNA-induced inflammation via the cGAS–STING pathway.

Laurindo L.F., Dogani Rodrigues V., de Lima E.P., Leme Boaro B., Mendes Peloi J.M., Ferraroni Sanches R.C., Penteado Detregiachi C.R., José Tofano R., Angelica Miglino M., Sloan K.P., Sloan L.A., Barbalho S.M.

Cardiovascular diseases are the primary cause of mortality worldwide. In this scenario, atherosclerotic cardiovascular outcomes dominate since their incidence increases as populations grow and age. Atherosclerosis is a chronic inflammatory disease that affects arteries. Although its pathophysiology is heterogeneous, some genes are indissociably associated with its occurrence, and understanding their effects on the disease’s occurrence could undoubtedly define effective screening and treatment strategies. One such gene is NEDD4L. The NEDD4L gene is related to ubiquitin ligase enzyme activities. It is essential to regulate vascular inflammation, atherosclerosis plaque stability, endothelial and vascular smooth cell function, and lipid metabolism, particularly in controlling cholesterol levels. However, the evidence is dubious, and no review has yet synthesized the effects of targeting NEDD4L on atherosclerosis. Therefore, our review aims to fill this gap by analyzing the literature on NEDD4L concerning atherosclerosis occurrence. To achieve this goal, we performed a systematic literature search of reputable databases, including PubMed, Google Scholar, Web of Science, Scopus, and Embase. The inclusion criteria comprised peer-reviewed original studies using in vitro and animal models due to the unavailability of relevant clinical studies. Systematic reviews, meta-analyses, and articles that did not focus on the relationship between NEDD4L and atherosclerosis and those unrelated to this health condition were excluded. Studies not written in the English language were also excluded. The search strategy included studies from January 2000 to January 2025 in the final analysis to capture recent advancements. Following screening, five studies were included. Most of the included studies underscored NEDD4L’s role in increasing atherosclerosis plaque formation, but other studies indicated that stimulating NEDD4L may positively counter atherosclerosis plaque formation. Therefore, future research endeavors must address several limitations, which have been tentatively highlighted throughout the manuscript, for more informative research based on preclinical studies and to successfully translate the findings into clinical trials.