bims-mikwok 2024-04-14 papers

bims-mikwok

Biomed News

on Mitochondrial quality control

Issue of 2024–04–14
twenty-one papers selected by
Gavin McStay, Liverpool John Moores University

MITOCHONDRIAL IMPORT STRESS and PINK1-MEDIATED MITOPHAGY: THE ROLE of the PINK1-TOMM-TIMM23 SUPERCOMPLEX.
GTPBP8 modulates mitochondrial fission through a Drp1-dependent process.
Curcumin simultaneously improves mitochondrial dynamics and myocardial cell bioenergy after sepsis via the SIRT1-DRP1/PGC-1α pathway.
Fatty acyl-coenzyme A activates mitochondrial division through oligomerization of MiD49 and MiD51.
Evaluation of Mitochondrial Phagy (Mitophagy) in Human Non-small Adenocarcinoma Tumor Cells.
Cardiac-specific deletion of heat shock protein 60 induces mitochondrial stress and disrupts heart development in mice.
Author Correction: The nascent polypeptide-associated complex subunit Egd1 is required for efficient selective mitochondrial degradation in budding yeast.
Mitophagy Upregulation Occurs Early in the Neurodegenerative Process Mediated by α-Synuclein.
Mitochondrial fission: a new mechanism of hypertension and cardiovascular remodeling induced by Angiotensin II.
Combination of bone marrow mesenchymal stem cells and moxibustion restores cyclophosphamide-induced premature ovarian insufficiency by improving mitochondrial function and regulating mitophagy.
Balbiani body of basal insects is potentially involved in multiplication and selective elimination of mitochondria.
Promoting mitochondrial dynamics by inhibiting the PINK1/PRKN pathway to relieve diabetic nephropathy.
Phosphoglycerate mutase 5 exacerbates liver ischemia-reperfusion injury by activating mitochondrial fission.
Targeting Mitochondrial Dynamics during Lower-Limb Ischemia Reperfusion in Young and Old Mice: Effect of Mitochondrial Fission Inhibitor-1 (mDivi-1).
Mechanical regulation of mitochondrial morphodynamics in cancer cells by extracellular microenvironment.
Bacterial muropeptides promote OXPHOS and suppress mitochondrial stress in mammals.
Mitochondrial stress in GABAergic neurons non-cell autonomously regulates organismal health and aging.
Enhanced mitochondrial fusion during a critical period of synaptic plasticity in adult-born neurons.
Targeting SLC22A5 fosters mitophagy inhibition-mediated macrophage immunity against septic acute kidney injury upon CD47-SIRPα axis blockade.
A tipping point in dihydroxyacetone exposure: mitochondrial stress and metabolic reprogramming alter survival in rat cardiomyocytes H9c2 cells.
Mdivi-1: Effective but complex mitochondrial fission inhibitor.

Autophagy. 2024 Apr 10.

MITOCHONDRIAL IMPORT STRESS and PINK1-MEDIATED MITOPHAGY: THE ROLE of the PINK1-TOMM-TIMM23 SUPERCOMPLEX.

Mohamed A Eldeeb, Armaan Fallahi, Andrea Soumbasis, Andrew N Bayne, Jean-François Trempe, Edward A Fon.

  Mutations in the PINK1 kinase cause Parkinson disease (PD) through physiological processes that are not yet fully elucidated. PINK1 kinase accumulates selectively on damaged mitochondria, where it recruits the E3 ubiquitin ligase PRKN/Parkin to mediate mitophagy. Upon mitochondrial import failure, PINK1 accumulates in association with the translocase of outer mitochondrial membrane (TOMM). However, the molecular basis of this PINK1 accumulation on the TOMM complex remain elusive. We recently demonstrated that TIMM23 (translocase of the inner mitochondrial membrane 23) is a component of the PINK1-supercomplex formed in response to mitochondrial stress. We also uncovered that PINK1 is required for the formation of this supercomplex and highlighted the biochemical regulation and significance of this supercomplex; expanding our understanding of mitochondrial quality control and PD pathogenesis.

Keywords:  Mitochondrial import; PINK1; Parkinson’s disease; mitochondrial quality control; mitophagy

DOI:  https://doi.org/10.1080/15548627.2024.2340399
J Cell Sci. 2024 Apr 08. pii: jcs.261612. [Epub ahead of print]

GTPBP8 modulates mitochondrial fission through a Drp1-dependent process.

Xiumei He, Liang Wang, Hoi Ying Tsang, Xiaonan Liu, Xiaofeng Yang, Ziqi Guo, Cheng Yang, Qiong Wu, Zuping Zhou, Xiaobo Cen, Hongxia Zhao.

  Mitochondrial fission is a tightly regulated process involving multiple proteins and cell signaling. Despite extensive studies on mitochondrial fission factors, our understanding of the regulatory mechanisms remains limited. This study shows the critical role of a mitochondrial GTPase, GTPBP8, in orchestrating mitochondrial fission. Depletion of GTPBP8 resulted in drastic elongation and interconnectedness of mitochondria. Conversely, overexpression of GTPBP8 shifted mitochondrial morphology from tubular to fragmented. Notably, the induced mitochondrial fragmentation from GTPBP8 overexpression was inhibited in cells either depleted of the mitochondrial fission protein Drp1 or carrying mutated forms of Drp1. Importantly, downregulation of GTPBP8 caused an increase in oxidative stress, modulating cell signaling involved in the heightened phosphorylation of Drp1 at Ser637. This phosphorylation hindered the recruitment of Drp1 to mitochondria, leading to mitochondrial fission defects. On the other hand, GTPBP8 overexpression triggered enhanced recruitment and assembly of Drp1 to mitochondria. In summary, our study illuminates the cellular function of GTPBP8 as a pivotal modulator of the mitochondrial division apparatus, inherently reliant on its influence on Drp1.

Keywords:  Drp1; Fission; GTPBP8; Mitochondria; Phosphorylation

DOI:  https://doi.org/10.1242/jcs.261612
Heliyon. 2024 Apr 15. 10(7): e28501

Curcumin simultaneously improves mitochondrial dynamics and myocardial cell bioenergy after sepsis via the SIRT1-DRP1/PGC-1α pathway.

Dongyao Hou, Haitang Liao, Shuai Hao, Ruixue Liu, He Huang, Chenyang Duan.

  Septic cardiomyopathy (SCM) is associated with an imbalance in mitochondrial quality and high mortality rates, with no effective treatment developed to date. Curcumin provides antioxidant, anti-inflammatory, cardiovascular, and mitochondrial protection. However, curcumin has not been confirmed to improve cardiac dysfunction in sepsis. We hypothesized that curcumin can reduce abnormal inflammatory responses by improving mitochondrial function as a novel mechanism to improve SCM. To explore this hypothesis, we used an in vivo male C57BL/6 mouse sepsis model and an in vitro model of lipopolysaccharide-stimulated HL-1 cells. The effects of curcumin on sepsis-induced cardiac dysfunction, inflammatory responses, and mitochondrial quality of cardiac cells were observed using quantitative polymerase chain reaction, western blotting, echocardiography, and transmission electron microscopy. Curcumin activated sirtuin 1 (SIRT1); increased expression of the mitochondrial biogenesis-related genes Pgc1α, Tfam, and Nrf2; reduced dynamin-related protein 1 translocation from the cytoplasm to mitochondria; and restored the mitochondrial morphology and function in cardiac cells. Accordingly, curcumin protected heart function after septic shock and alleviated the effects of SCM. SIRT1 knockdown reversed the protective effects of curcumin on mitochondria. Therefore, curcumin promotes mitochondrial biogenesis and inhibits mitochondrial fragmentation by activating SIRT1, thereby improving the mitochondrial quality and reducing oxidative stress in cardiomyocytes and sepsis-induced cardiac dysfunction. These findings provide new evidence supporting the use of curcumin to treat SCM.

Keywords:  Cardiac dysfunction; Inflammation; Mitochondrial biogenesis; Oxidative stress

DOI:  https://doi.org/10.1016/j.heliyon.2024.e28501
Nat Cell Biol. 2024 Apr 09.

Fatty acyl-coenzyme A activates mitochondrial division through oligomerization of MiD49 and MiD51.

Ao Liu, Frieda Kage, Asan F Abdulkareem, Mac Pholo Aguirre-Huamani, Gracie Sapp, Halil Aydin, Henry N Higgs.

Mitochondrial fission occurs in many cellular processes, but the regulation of fission is poorly understood. We show that long-chain acyl-coenzyme A (LCACA) activates two related mitochondrial fission proteins, MiD49 and MiD51, by inducing their oligomerization, which activates their ability to stimulate the DRP1 GTPase. The 1:1 stoichiometry of LCACA:MiD in the oligomer suggests interaction in the previously identified nucleotide-binding pocket, and a point mutation in this pocket reduces LCACA binding and LCACA-induced oligomerization for MiD51. In cells, this LCACA binding mutant does not assemble into puncta on mitochondria or rescue MiD49/51 knockdown effects on mitochondrial length and DRP1 recruitment. Furthermore, cellular treatment with BSA-bound oleic acid, which causes increased LCACA, promotes mitochondrial fission in an MiD49/51-dependent manner. These results suggest that LCACA is an endogenous ligand for MiDs, inducing mitochondrial fission and providing a potential mechanism for fatty-acid-induced mitochondrial division. Finally, MiD49 or MiD51 oligomers synergize with Mff, but not with actin filaments, in DRP1 activation, suggesting distinct pathways for DRP1 activation.

DOI: https://doi.org/10.1038/s41556-024-01400-3
Methods Mol Biol. 2024 Apr 13.

Evaluation of Mitochondrial Phagy (Mitophagy) in Human Non-small Adenocarcinoma Tumor Cells.

Javad Alizadeh, Simone C da Silva Rosa, Marco Cordani, Saeid Ghavami.

  Non-small cell lung cancer (NSCLC) is a predominant form of lung cancer characterized by its aggressive nature and high mortality rate, primarily due to late-stage diagnosis and metastatic spread. Recent studies underscore the pivotal role of mitophagy, a selective form of autophagy targeting damaged or superfluous mitochondria, in cancer biology, including NSCLC. Mitophagy regulation may influence cancer cell survival, proliferation, and metastasis by modulating mitochondrial quality and cellular energy homeostasis. Herein, we present a comprehensive methodology developed in our laboratory for the evaluation of mitophagy in NSCLC tumor cells. Utilizing a combination of immunoblotting, immunocytochemistry, and fluorescent microscopy, we detail the steps to quantify early and late mitophagy markers and mitochondrial dynamics. Our findings highlight the potential of targeting mitophagy pathways as a novel therapeutic strategy in NSCLC, offering insights into the complex interplay between mitochondrial dysfunction and tumor progression. This study not only sheds light on the significance of mitophagy in NSCLC but also establishes a foundational approach for its investigation, paving way for future research in this critical area of cancer biology.

Keywords:  Autophagy; Cellular homeostasis; Mitochondrial dynamics; Mitophagy; Non-small cell adenocarcinoma

DOI:  https://doi.org/10.1007/7651_2024_532
Biochem Biophys Res Commun. 2024 Apr 04. pii: S0006-291X(24)00419-4. [Epub ahead of print]710 149883

Cardiac-specific deletion of heat shock protein 60 induces mitochondrial stress and disrupts heart development in mice.

Tao Shen, Shuting Wang, Can Huang, Siting Zhu, Xiangbin Zhu, Na Li, Hong Wang, Lei Huang, Mingming Ren, Zhen Han, Jianjun Ge, Ze'e Chen, Kunfu Ouyang.

  Congenital heart diseases are the most common birth defects around the world. Emerging evidence suggests that mitochondrial homeostasis is required for normal heart development. In mitochondria, a series of molecular chaperones including heat shock protein 60 (HSP60) are engaged in assisting the import and folding of mitochondrial proteins. However, it remains largely obscure whether and how these mitochondrial chaperones regulate cardiac development. Here, we generated a cardiac-specific Hspd1 deletion mouse model by αMHC-Cre and investigated the role of HSP60 in cardiac development. We observed that deletion of HSP60 in embryonic cardiomyocytes resulted in abnormal heart development and embryonic lethality, characterized by reduced cardiac cell proliferation and thinner ventricular walls, highlighting an essential role of cardiac HSP60 in embryonic heart development and survival. Our results also demonstrated that HSP60 deficiency caused significant downregulation of mitochondrial ETC subunits and induced mitochondrial stress. Analysis of gene expression revealed that P21 that negatively regulates cell proliferation is significantly upregulated in HSP60 knockout hearts. Moreover, HSP60 deficiency induced activation of eIF2α-ATF4 pathway, further indicating the underlying mitochondrial stress in cardiomyocytes after HSP60 deletion. Taken together, our study demonstrated that regular function of mitochondrial chaperones is pivotal for maintaining normal mitochondrial homeostasis and embryonic heart development.

Keywords:  ATF4; Cardiomyocytes; Heart development; Heat shock protein 60; Mitochondrial stress

DOI:  https://doi.org/10.1016/j.bbrc.2024.149883
Sci Rep. 2024 Apr 11. 14(1): 8477

Author Correction: The nascent polypeptide-associated complex subunit Egd1 is required for efficient selective mitochondrial degradation in budding yeast.

Yuan Tian, Koji Okamoto.

DOI: https://doi.org/10.1038/s41598-024-59028-0
Mol Neurobiol. 2024 Apr 06.

Mitophagy Upregulation Occurs Early in the Neurodegenerative Process Mediated by α-Synuclein.

Sarah Hui, Jimmy George, Minesh Kapadia, Hien Chau, Zahn Bariring, Rebecca Earnshaw, Kashfia Shafiq, Lorraine V Kalia, Suneil K Kalia.

  Parkinson's disease (PD) is a progressive neurogenerative movement disorder characterized by dopaminergic cell death within the substantia nigra pars compacta (SNpc) due to the aggregation-prone protein α-synuclein. Accumulation of α-synuclein is implicated in mitochondrial dysfunction and disruption of the autophagic turnover of mitochondria, or mitophagy, which is an essential quality control mechanism proposed to preserve mitochondrial fidelity in response to aging and stress. Yet, the precise relationship between α-synuclein accumulation, mitochondrial autophagy, and dopaminergic cell loss remains unresolved. Here, we determine the kinetics of α-synuclein overexpression and mitophagy using the pH-sensitive fluorescent mito-QC reporter. We find that overexpression of mutant A53T α-synuclein in either human SH-SY5Y cells or rat primary cortical neurons induces mitophagy. Moreover, the accumulation of mutant A53T α-synuclein in the SNpc of rats results in mitophagy dysregulation that precedes the onset of dopaminergic neurodegeneration. This study reveals a role for mutant A53T α-synuclein in inducing mitochondrial dysfunction, which may be an early event contributing to neurodegeneration.

Keywords:  Alpha-synuclein; Lysosomes; Mitochondria dysfunction; Mitophagy; Neurodegeneration; Parkinson’s disease; Substantia nigra pars compacta

DOI:  https://doi.org/10.1007/s12035-024-04131-6
Hypertens Res. 2024 Apr 10.

Mitochondrial fission: a new mechanism of hypertension and cardiovascular remodeling induced by Angiotensin II.

Kohei Ueda, Shigeru Shibata.



Keywords:  Fission; Mitochondria; Vascular dysfunction

DOI:  https://doi.org/10.1038/s41440-024-01670-2
Stem Cell Res Ther. 2024 Apr 08. 15(1): 102

Combination of bone marrow mesenchymal stem cells and moxibustion restores cyclophosphamide-induced premature ovarian insufficiency by improving mitochondrial function and regulating mitophagy.

Ge Lu, Hong-Xiao Li, Zi-Wei Song, Jia Luo, Yan-Liang Fan, Yao-Li Yin, Jie Shen, Mei-Hong Shen.

   BACKGROUND: Premature ovarian insufficiency (POI) is a major cause of infertility. In this study, we aimed to investigate the effects of the combination of bone marrow mesenchymal stem cells (BMSCs) and moxibustion (BMSCs-MOX) on POI and evaluate the underlying mechanisms.
METHODS: A POI rat model was established by injecting different doses of cyclophosphamide (Cy). The modeling of POI and the effects of the treatments were assessed by evaluating estrous cycle, serum hormone levels, ovarian weight, ovarian index, and ovarian histopathological analysis. The effects of moxibustion on BMSCs migration were evaluated by tracking DiR-labeled BMSCs and analyzing the expression of chemokines stromal cell-derived factor 1 (Sdf1) and chemokine receptor type 4 (Cxcr4). Mitochondrial function and mitophagy were assessed by measuring the levels of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), ATP, and the mitophagy markers (Drp1, Pink1, and Parkin). Furthermore, the mitophagy inhibitor Mdivi-1 and the mitophagy activator CCCP were used to confirm the role of mitophagy in Cy-induced ovarian injury and the underlying mechanism of combination therapy.
RESULTS: A suitable rat model of POI was established using Cy injection. Compared to moxibustion or BMSCs transplantation alone, BMSCs-MOX showed improved outcomes, such as reduced estrous cycle disorders, improved ovarian weight and index, normalized serum hormone levels, increased ovarian reserve, and reduced follicle atresia. Moxibustion enhanced Sdf1 and Cxcr4 expression, promoting BMSCs migration. BMSCs-MOX reduced ROS levels; upregulated MMP and ATP levels in ovarian granulosa cells (GCs); and downregulated Drp1, Pink1, and Parkin expression in ovarian tissues. Mdivi-1 significantly mitigated mitochondrial dysfunction in ovarian GCs and improved ovarian function. CCCP inhibited the ability of BMSCs-MOX treatment to regulate mitophagy and ameliorate Cy-induced ovarian injury.
CONCLUSIONS: Moxibustion enhanced the migration and homing of BMSCs following transplantation and improves their ability to repair ovarian damage. The combination of BMSCs and moxibustion effectively reduced the excessive activation of mitophagy, which helped prevent mitochondrial damage, ultimately improving ovarian function. These findings provide a novel approach for the treatment of pathological ovarian aging and offer new insights into enhancing the efficacy of stem cell therapy for POI patients.

Keywords:  Bone marrow mesenchymal stem cells; Mitochondrial function; Mitophagy; Moxibustion; Premature ovarian insufficiency

DOI:  https://doi.org/10.1186/s13287-024-03709-0
Sci Rep. 2024 04 09. 14(1): 8263

Balbiani body of basal insects is potentially involved in multiplication and selective elimination of mitochondria.

Malgorzata Sekula, Waclaw Tworzydlo, Szczepan M Bilinski.

Oocytes of both vertebrates and invertebrates often contain an intricate organelle assemblage, termed the Balbiani body (Bb). It has previously been suggested that this assemblage is involved in the delivery of organelles and macromolecules to the germ plasm, formation of oocyte reserve materials, and transfer of mitochondria to the next generation. To gain further insight into the function of the Bb, we performed a series of analyses and experiments, including computer-aided 3-dimensional reconstructions, detection of DNA (mtDNA) synthesis as well as immunolocalization studies. We showed that in orthopteran Meconema meridionale, the Bb comprises a network of mitochondria and perinuclear nuage aggregations. As oogenesis progresses, the network expands filling almost entire ooplasm, then partitions into several smaller entities, termed micro-networks, and ultimately into individual mitochondria. As in somatic cells, this process involves microfilaments and elements of endoplasmic reticulum. We showed also that at least some of the individual mitochondria are surrounded by phagophores and eliminated via mitophagy. These findings support the idea that the Bb is implicated in the multiplication and selective elimination of (defective) mitochondria and therefore may participate in the transfer of undamaged (healthy) mitochondria to the next generation.

DOI: https://doi.org/10.1038/s41598-024-58997-6
Dis Model Mech. 2024 Apr 11. pii: dmm.050471. [Epub ahead of print]

Promoting mitochondrial dynamics by inhibiting the PINK1/PRKN pathway to relieve diabetic nephropathy.

Jun-Yi Zhu, Joyce van de Leemput, Zhe Han.

  Diabetes is a metabolic disorder characterized by high blood glucose levels and is a leading cause of kidney disease. Diabetic nephropathy has been attributed to dysfunctional mitochondria. However, many questions remain about the exact mechanism. The structure, function, and molecular pathways between mammalian podocytes and Drosophila nephrocytes are highly conserved, therefore we used flies on a high-sucrose diet to model type 2 diabetic nephropathy. The nephrocytes of high-sucrose diet flies showed significant functional decline and decreased cell size, associated with a shortened lifespan. Structurally, the nephrocytes filtration structure known as the slit diaphragm was disorganized. At the cellular level, we found altered mitochondrial dynamics and dysfunction. Regulating mitochondrial dynamics by either genetic modification of the Pink1/Park (mammalian PINK1/PRKN) pathway or treatment with BGP-15, mitigated the mitochondrial defects and nephrocyte functional decline. These findings support a role for Pink1/Park-mediated mitophagy and associated control of mitochondrial dynamics, essential for function, in diabetic nephropathy; and demonstrate that targeting this pathway might provide therapeutic benefits in type 2 diabetic nephropathy.

Keywords:   Drosophila ; Diabetes; Mitochondria; Nephrocyte; PINK1; PRKN

DOI:  https://doi.org/10.1242/dmm.050471
Sci Rep. 2024 Apr 12. 14(1): 8535

Phosphoglycerate mutase 5 exacerbates liver ischemia-reperfusion injury by activating mitochondrial fission.

Hongwei Tang, Qiwen Yu, Xu Chen, Jiakai Zhang, Danfeng Guo, Wenzhi Guo, Shuijun Zhang, Xiaoyi Shi.

  Although the death of hepatocytes is a crucial trigger of liver ischemia-reperfusion (I/R) injury, the regulation of liver I/R-induced hepatocyte death is still poorly understood. Phosphoglycerate mutase 5 (PGAM5), a mitochondrial Serine/Threonine protein phosphatase, regulates mitochondrial dynamics and is involved in the process of both apoptosis and necrotic. However, it is still unclear what role PGAM5 plays in the death of hepatocytes induced by I/R. Using a PGAM5-silence mice model, we investigated the role of PGAM5 in liver I/R injury and its relevant molecular mechanisms. Our data showed that PGAM5 was highly expressed in mice with liver I/R injury. Silence of PGAM5 could decrease I/R-induced hepatocyte death in mice. In subcellular levels, the silence of PGAM5 could restore mitochondrial membrane potential, increase mitochondrial DNA copy number and transcription levels, inhibit ROS generation, and prevent I/R-induced opening of abnormal mPTP. As for the molecular mechanisms, we indicated that the silence of PGAM5 could inhibit Drp1(S616) phosphorylation, leading to a partial reduction of mitochondrial fission. In addition, Mdivi-1 could inhibit mitochondrial fission, decrease hepatocyte death, and attenuate liver I/R injury in mice. In conclusion, our data reveal the molecular mechanism of PGAM5 in driving hepatocyte death through activating mitochondrial fission in liver I/R injury.

Keywords:  Liver I/R injury; Mitochondrial fission; Mitochondrial quality control; PGAM5

DOI:  https://doi.org/10.1038/s41598-024-58748-7
Int J Mol Sci. 2024 Apr 04. pii: 4025. [Epub ahead of print]25(7):

Targeting Mitochondrial Dynamics during Lower-Limb Ischemia Reperfusion in Young and Old Mice: Effect of Mitochondrial Fission Inhibitor-1 (mDivi-1).

Stéphanie Paradis, Anne-Laure Charles, Margherita Giannini, Alain Meyer, Anne Lejay, Samy Talha, Gilles Laverny, Anne Charloux, Bernard Geny.

  Peripheral arterial disease (PAD) strikes more than 200 million people worldwide and has a severe prognosis by potentially leading to limb amputation and/or death, particularly in older patients. Skeletal muscle mitochondrial dysfunctions and oxidative stress play major roles in this disease in relation with ischemia-reperfusion (IR) cycles. Mitochondrial dynamics through impairment of fission-fusion balance may contribute to skeletal muscle pathophysiology, but no data were reported in the setting of lower-limb IR despite the need for new therapeutic options. We, therefore, investigated the potential protective effect of mitochondrial division inhibitor-1 (mDivi-1; 50 mg/kg) in young (23 weeks) and old (83 weeks) mice submitted to two-hour ischemia followed by two-hour reperfusion on systemic lactate, muscle mitochondrial respiration and calcium retention capacity, and on transcripts specific for oxidative stress and mitochondrial dynamics. At the systemic levels, an IR-related increase in circulating lactate was still major despite mDivi-1 use (+305.9% p < 0.0001, and +269.4% p < 0.0001 in young and old mice, respectively). Further, IR-induced skeletal muscle mitochondrial dysfunctions (more severely impaired mitochondrial respiration in old mice (OXPHOS CI state, -68.2% p < 0.0001 and -84.9% p < 0.0001 in 23- and 83-week mice) and reduced calcium retention capacity (-46.1% p < 0.001 and -48.2% p = 0.09, respectively) were not corrected by mDivi-1 preconditioning, whatever the age. Further, mDivi-1 treatment did not oppose superoxide anion production (+71.4% p < 0.0001 and +37.5% p < 0.05, respectively). At the transcript level, markers of antioxidant enzymes (SOD 1, SOD 2, catalase, and GPx) and fission markers (Drp1, Fis) remained unchanged or tended to be decreased in the ischemic leg. Fusion markers such as mitofusin 1 or 2 decreased significantly after IR in both groups. In conclusion, aging enhanced the deleterious effects or IR on muscle mitochondrial respiration, and in this setting of lower-limb IR, mDivi-1 failed to protect the skeletal muscle both in young and old mice.

Keywords:  aging; ischemia reperfusion; lactate; mitochondria; mitochondrial dynamics; muscle; peripheral arterial disease; reactive oxygen species

DOI:  https://doi.org/10.3390/ijms25074025
Biomater Biosyst. 2024 Jun;14 100093

Mechanical regulation of mitochondrial morphodynamics in cancer cells by extracellular microenvironment.

Mariia Lunova, Milan Jirsa, Alexandr Dejneka, Gareth John Sullivan, Oleg Lunov.

  Recently, it has been recognized that physical abnormalities (e.g. elevated solid stress, elevated interstitial fluid pressure, increased stiffness) are associated with tumor progression and development. Additionally, these mechanical forces originating from tumor cell environment through mechanotransduction pathways can affect metabolism. On the other hand, mitochondria are well-known as bioenergetic, biosynthetic, and signaling organelles crucial for sensing stress and facilitating cellular adaptation to the environment and physical stimuli. Disruptions in mitochondrial dynamics and function have been found to play a role in the initiation and advancement of cancer. Consequently, it is logical to hypothesize that mitochondria dynamics subjected to physical cues may play a pivotal role in mediating tumorigenesis. Recently mitochondrial biogenesis and turnover, fission and fusion dynamics was linked to mechanotransduction in cancer. However, how cancer cell mechanics and mitochondria functions are connected, still remain poorly understood. Here, we discuss recent studies that link mechanical stimuli exerted by the tumor cell environment and mitochondria dynamics and functions. This interplay between mechanics and mitochondria functions may shed light on how mitochondria regulate tumorigenesis.

Keywords:  Cancer; Mechanotransduction; Mitochondria; Mitochondrial dynamics; Tumor metabolism

DOI:  https://doi.org/10.1016/j.bbiosy.2024.100093
Cell Rep. 2024 Apr 06. pii: S2211-1247(24)00395-4. [Epub ahead of print]43(4): 114067

Bacterial muropeptides promote OXPHOS and suppress mitochondrial stress in mammals.

Dong Tian, Mingxue Cui, Min Han.

  Mitochondrial dysfunction critically contributes to many major human diseases. The impact of specific gut microbial metabolites on mitochondrial functions of animals and the underlying mechanisms remain to be uncovered. Here, we report a profound role of bacterial peptidoglycan muropeptides in promoting mitochondrial functions in multiple mammalian models. Muropeptide addition to human intestinal epithelial cells (IECs) leads to increased oxidative respiration and ATP production and decreased oxidative stress. Strikingly, muropeptide treatment recovers mitochondrial structure and functions and inhibits several pathological phenotypes of fibroblast cells derived from patients with mitochondrial disease. In mice, muropeptides accumulate in mitochondria of IECs and promote small intestinal homeostasis and nutrient absorption by modulating energy metabolism. Muropeptides directly bind to ATP synthase, stabilize the complex, and promote its enzymatic activity in vitro, supporting the hypothesis that muropeptides promote mitochondria homeostasis at least in part by acting as ATP synthase agonists. This study reveals a potential treatment for human mitochondrial diseases.

Keywords:  ATP synthase; CP: Cell biology; CP: Metabolism; Leigh syndrome; PGN; ROS; antibiotic-induced microbiome depletion; electron transfer chain; energy metabolism; intestinal epithelial cells; intestinal homeostasis; mitochondrial diseases; oxidative phosphorylation; oxidative stress; peptidoglycan

DOI:  https://doi.org/10.1016/j.celrep.2024.114067
bioRxiv. 2024 Mar 25. pii: 2024.03.20.585932. [Epub ahead of print]

Mitochondrial stress in GABAergic neurons non-cell autonomously regulates organismal health and aging.

Laxmi Rathor, Shayla Curry, Youngyong Park, Taylor McElroy, Briana Robles, Yi Sheng, Wei-Wen Chen, Kisuk Min, Rui Xiao, Myon Hee Lee, Sung Min Han.

Mitochondrial stress within the nervous system can trigger non-cell autonomous responses in peripheral tissues. However, the specific neurons involved and their impact on organismal aging and health have remained incompletely understood. Here, we demonstrate that mitochondrial stress in γ-aminobutyric acid-producing (GABAergic) neurons in Caenorhabditis elegans ( C. elegans ) is sufficient to significantly alter organismal lifespan, stress tolerance, and reproductive capabilities. This mitochondrial stress also leads to significant changes in mitochondrial mass, energy production, and levels of reactive oxygen species (ROS). DAF-16/FoxO activity is enhanced by GABAergic neuronal mitochondrial stress and mediates the induction of these non-cell-autonomous effects. Moreover, our findings indicate that GABA signaling operates within the same pathway as mitochondrial stress in GABAergic neurons, resulting in non-cell-autonomous alterations in organismal stress tolerance and longevity. In summary, these data suggest the crucial role of GABAergic neurons in detecting mitochondrial stress and orchestrating non-cell-autonomous changes throughout the organism.

DOI: https://doi.org/10.1101/2024.03.20.585932
Neuron. 2024 Mar 26. pii: S0896-6273(24)00167-3. [Epub ahead of print]

Enhanced mitochondrial fusion during a critical period of synaptic plasticity in adult-born neurons.

Sandra M V Kochan, Meret Cepero Malo, Milica Jevtic, Hannah M Jahn-Kelleter, Gulzar A Wani, Kristiano Ndoci, Laura Pérez-Revuelta, Felix Gaedke, Iris Schäffner, Dieter Chichung Lie, Astrid Schauss, Matteo Bergami.

  Integration of new neurons into adult hippocampal circuits is a process coordinated by local and long-range synaptic inputs. To achieve stable integration and uniquely contribute to hippocampal function, immature neurons are endowed with a critical period of heightened synaptic plasticity, yet it remains unclear which mechanisms sustain this form of plasticity during neuronal maturation. We found that as new neurons enter their critical period, a transient surge in fusion dynamics stabilizes elongated mitochondrial morphologies in dendrites to fuel synaptic plasticity. Conditional ablation of fusion dynamics to prevent mitochondrial elongation selectively impaired spine plasticity and synaptic potentiation, disrupting neuronal competition for stable circuit integration, ultimately leading to decreased survival. Despite profuse mitochondrial fragmentation, manipulation of competition dynamics was sufficient to restore neuronal survival but left neurons poorly responsive to experience at the circuit level. Thus, by enabling synaptic plasticity during the critical period, mitochondrial fusion facilitates circuit remodeling by adult-born neurons.

Keywords:  LTP; Mfn2; adult neurogenesis; competition; experience; hippocampus; mitochondria; mitochondrial fusion; neural stem cell; synaptic plasticity

DOI:  https://doi.org/10.1016/j.neuron.2024.03.013
Heliyon. 2024 Apr 15. 10(7): e26791

Targeting SLC22A5 fosters mitophagy inhibition-mediated macrophage immunity against septic acute kidney injury upon CD47-SIRPα axis blockade.

Yu Jia, Jun-Hua Li, Bang-Chuan Hu, Xia Huang, Xi Yang, Yan-Yan Liu, Juan-Juan Cai, Xue Yang, Jun-Mei Lai, Ye Shen, Jing-Quan Liu, Hai-Ping Zhu, Xiang-Ming Ye, Shi-Jing Mo.

  Efferocytosis of apoptotic neutrophils (PMNs) by macrophages is helpful for inflammation resolution and injury repair, but the role of efferocytosis in intrinsic nature of macrophages during septic acute kidney injury (AKI) remains unknown. Here we report that CD47 and signal regulatory protein alpha (SIRPα)-the anti-efferocytotic 'don't eat me' signals-are highly expressed in peripheral blood mononuclear cells (PBMCs) from patients with septic AKI and kidney samples from mice with polymicrobial sepsis and endotoxin shock. Conditional knockout (CKO) of SIRPA in macrophages ameliorates AKI and systemic inflammation response in septic mice, accompanied by an escalation in mitophagy inhibition of macrophages. Ablation of SIRPA transcriptionally downregulates solute carrier family 22 member 5 (SLC22A5) in the lipopolysaccharide (LPS)-stimulated macrophages that efferocytose apoptotic neutrophils (PMNs). Targeting SLC22A5 renders mitophagy inhibition of macrophages in response to LPS stimuli, improves survival and deters development of septic AKI. Our study supports further clinical investigation of CD47-SIRPα signalling in sepsis and proposes that SLC22A5 might be a promising immunotherapeutic target for septic AKI.

Keywords:  CD47-Signal regulatory protein alpha; Macrophage immune; Mitophagy; Septic acute kidney injury; Solute carrier family 22 member 5

DOI:  https://doi.org/10.1016/j.heliyon.2024.e26791
Chem Biol Interact. 2024 Apr 04. pii: S0009-2797(24)00137-6. [Epub ahead of print]394 110991

A tipping point in dihydroxyacetone exposure: mitochondrial stress and metabolic reprogramming alter survival in rat cardiomyocytes H9c2 cells.

Arlet Hernandez, Luxene Belfleur, Marie Migaud, Natalie R Gassman.

  Exogenous exposures to the triose sugar dihydroxyacetone (DHA) occur from sunless tanning products and electronic cigarette aerosol. Once inhaled or absorbed, DHA enters cells, is converted to dihydroxyacetone phosphate (DHAP), and incorporated into several metabolic pathways. Cytotoxic effects of DHA vary across the cell types depending on the metabolic needs of the cells, and differences in the generation of reactive oxygen species (ROS), cell cycle arrest, and mitochondrial dysfunction have been reported. We have shown that cytotoxic doses of DHA induced metabolic imbalances in glycolysis and oxidative phosphorylation in liver and kidney cell models. Here, we examine the dose-dependent effects of DHA on the rat cardiomyocyte cell line, H9c2. Cells begin to experience cytotoxic effects at low millimolar doses, but an increase in cell survival was observed at 2 mM DHA. We confirmed that 2 mM DHA increased cell survival compared to the low cytotoxic 1 mM dose and investigated the metabolic differences between these two low DHA doses. Exposure to 1 mM DHA showed changes in the cell's fuel utilization, mitochondrial reactive oxygen species (ROS), and transient changes in the glycolysis and mitochondrial energetics, which normalized 24 h after exposure. The 2 mM dose induced robust changes in mitochondrial flux through acetyl CoA and elevated expression of fatty acid synthase. Distinct from the 1 mM dose, the 2 mM exposure increased mitochondrial ROS and NAD(P)H levels, and sustained changes in LDHA/LDHB and acetyl CoA-associated enzymes were observed. Although the cells were exposed to low cytotoxic (1 mM) and non-cytotoxic (2 mM) acute doses of DHA, significant changes in mitochondrial metabolic pathways occurred. Further, the proliferation increase at the acute 2 mM DHA dose suggests a metabolic adaption occurred with sustained consequences in survival and proliferation. With increased exogenous exposure to DHA through e-cigarette aerosol, this work suggests cell metabolic changes induced by acute or potentially chronic exposures could impact cell function and survival.

Keywords:  Cell survival; Dihydroxyacetone; Electronic cigarette; Fatty acid; Heart; Metabolism; Mitochondria

DOI:  https://doi.org/10.1016/j.cbi.2024.110991
Biochem Biophys Res Commun. 2024 Apr 03. pii: S0006-291X(24)00422-4. [Epub ahead of print]710 149886

Mdivi-1: Effective but complex mitochondrial fission inhibitor.

Seor I Ahn, Sung Kyung Choi, Myoung Jun Kim, Jinhong Wie, Jueng Soo You.

  Mdivi-1, Mitochondrial DIVIsion inhibitor 1, has been widely employed in research under the assumption that it exclusively influences mitochondrial fusion, but effects other than mitochondrial dynamics have been underinvestigated. This paper provides transcriptome and DNA methylome-wide analysis for Mdivi-1 treated SH-SY5Y human neuroblastoma cells using RNA sequencing (RNA-seq) and methyl capture sequencing (MC-seq) methods. Gene ontology analysis of RNA sequences revealed that p53 transcriptional gene network and DNA replication initiation-related genes were significantly up and down-regulated, respectively, showing the correlation with the arrest cell cycle in the G1 phase. MC-seq, a powerful sequencing method for capturing DNA methylation status in CpG sites, revealed that although Mdivi-1 does not induce dramatic DNA methylation change, the subtle alterations were concentrated within the CpG island. Integrative analysis of both sequencing data disclosed that the p53 transcriptional network was activated while the Parkinson's disease pathway was halted. Next, we investigated several changes in mitochondria in response to Mdivi-1. Copy number and transcription of mitochondrial DNA were suppressed. ROS levels increased, and elevated ROS triggered mitochondrial retrograde signaling rather than inducing direct DNA damage. In this study, we could better understand the molecular network of Mdivi-1 by analyzing DNA methylation and mRNA transcription in the nucleus and further investigating various changes in mitochondria, providing inspiration for studying nuclear-mitochondrial communications.

Keywords:  DNA methylome; Mdivi-1; Mitochondrial dynamics; Mitochondrial retrograde signaling; Transcriptome

DOI:  https://doi.org/10.1016/j.bbrc.2024.149886