bims-midtic 2023-12-24 papers

bims-midtic

Biomed News

on Mitochondrial dynamics and trafficking in cells

Issue of 2023–12–24
27 papers selected by
Omkar Joshi, Turku Bioscience

Neuron-targeted overexpression of caveolin-1 alleviates diabetes-associated cognitive dysfunction via regulating mitochondrial fission-mitophagy axis.
Muscle immune cells protect mitochondrial organelles during exercise.
Recombinant bovine FGF1 promotes muscle satellite cells mitochondrial fission and proliferation in serum-free conditions.
Mitochondrial quality control pathways sense mitochondrial protein import.
The role of mitochondrial quality control in chronic obstructive pulmonary disease.
Effects of CuSO4 on hepatic mitochondrial function, biogenesis and dynamics in mice.
Phosphatidate phosphatase Lipin1 involves in diabetic encephalopathy pathogenesis via regulating synaptic mitochondrial dynamics.
Mitochondrial dysfunction abrogates dietary lipid processing in enterocytes.
Mitochondrial network reorganization and transient expansion during oligodendrocyte generation.
Dynamin-related protein 1 is a critical regulator of mitochondrial calcium homeostasis during myocardial ischemia/reperfusion injury.
Confinement primes cells for faster migration by polarizing active mitochondria.
Inhibition of Drp1 orchestrates the responsiveness of breast cancer cells to paclitaxel but insignificantly relieves paclitaxel-related ovarian damage in mice.
Performance of TMRM and Mitotrackers in mitochondrial morphofunctional analysis of primary human skin fibroblasts.
Analysis of the Mitochondrial Density and Longitudinal Distribution in Rat Live-Skeletal Muscle Fibers by Confocal Microscopy.
Mitochondrial Network: Electric Cable and More.
Regulation of PM2.5 on mitochondrial damage in H9c2 cells through miR-421/SIRT3 pathway and protective effect of miR-421 inhibitor and resveratrol.
Role of mitochondrial fusion proteins MFN2 and OPA1 on lung cellular senescence in chronic obstructive pulmonary disease.
Diversity and Evolution of Mitochondrial Translation Apparatus.
Modified Hu-lu-ba-wan protects diabetic glomerular podocytes via promoting PKM2-mediated mitochondrial dynamic homeostasis.
Mtfp1 ablation enhances mitochondrial respiration and protects against hepatic steatosis.
Post-Transcriptional Methylation of Mitochondrial-tRNA Differentially Contributes to Mitochondrial Pathology.
Quantitative subcellular reconstruction reveals a lipid mediated inter-organelle biogenesis network.
Novel Relationship between Mitofusin 2-Mediated Mitochondrial Hyperfusion, Metabolic Remodeling, and Glycolysis in Pulmonary Arterial Endothelial Cells.
A gold-based inhibitor of oxidative phosphorylation is effective against triple negative breast cancer.
Intrageneric structural variation in organelle genomes from the genus Dystaenia (Apiaceae): genome rearrangement and mitochondrion-to-plastid DNA transfer.
A D-Y Shaped Neuropeptide Y Mimetic Peptide-Dye Self-Assembly with Maximal Emission Beyond 1300 nm and Glioma Mitochondrial Activity Modulation.
Mitochondrial replication's role in vertebrate mtDNA strand asymmetry.

Cell Commun Signal. 2023 Dec 15. 21(1): 357

Neuron-targeted overexpression of caveolin-1 alleviates diabetes-associated cognitive dysfunction via regulating mitochondrial fission-mitophagy axis.

Wenxin Tang, Chaoying Yan, Shuxuan He, Mengyu Du, Bo Cheng, Bin Deng, Shan Zhu, Yansong Li, Qiang Wang.

   BACKGROUND: Type 2 diabetes mellitus (T2DM) induced diabetes-associated cognitive dysfunction (DACD) that seriously affects the self-management of T2DM patients, is currently one of the most severe T2DM-associated complications, but the mechanistic basis remains unclear. Mitochondria are highly dynamic organelles, whose function refers to a broad spectrum of features such as mitochondrial dynamics, mitophagy and so on. Mitochondrial abnormalities have emerged as key determinants for cognitive function, the relationship between DACD and mitochondria is not well understood.
METHODS: Here, we explored the underlying mechanism of mitochondrial dysfunction of T2DM mice and HT22 cells treated with high glucose/palmitic acid (HG/Pal) focusing on the mitochondrial fission-mitophagy axis with drug injection, western blotting, Immunofluorescence, and electron microscopy. We further explored the potential role of caveolin-1 (cav-1) in T2DM induced mitochondrial dysfunction and synaptic alteration through viral transduction.
RESULTS: As previously reported, T2DM condition significantly prompted hippocampal mitochondrial fission, whereas mitophagy was blocked rather than increasing, which was accompanied by dysfunctional mitochondria and impaired neuronal function. By contrast, Mdivi-1 (mitochondrial division inhibitor) and urolithin A (mitophagy activator) ameliorated mitochondrial and neuronal function and thereafter lead to cognitive improvement by inhibiting excessive mitochondrial fission and giving rise to mitophagy, respectively. We have previously shown that cav-1 can significantly improve DACD by inhibiting ferroptosis. Here, we further demonstrated that cav-1 could not only inhibit mitochondrial fission via the interaction with GSK3β to modulate Drp1 pathway, but also rescue mitophagy through interacting with AMPK to activate PINK1/Parkin and ULK1-dependent signlings.
CONCLUSIONS: Overall, our data for the first time point to a mitochondrial fission-mitophagy axis as a driver of neuronal dysfunction in a phenotype that was exaggerated by T2DM, and the protective role of cav-1 in DACD. Graphic Summary Illustration. In T2DM, excessive mitochondrial fission and impaired mitophagy conspire to an altered mitochondrial morphology and mitochondrial dysfunction, with a consequent neuronal damage, overall suggesting an unbalanced mitochondrial fission-mitophagy axis. Upon cav-1 overexpression, GSK3β and AMPK are phosphorylated respectively to activate Drp1 and mitophagy-related pathways (PINK1 and ULKI), ultimately inhibits mitochondrial fission and enhances mitophagy. In the meantime, the mitochondrial morphology and neuronal function are rescued, indicating the protective role of cav-1 on mitochondrial fission-mitophagy axis. Video Abstract.

Keywords:  Caveolin-1; Diabetes-associated cognitive dysfunction; Mitochondrial fission; Mitophagy

DOI:  https://doi.org/10.1186/s12964-023-01328-5
Nature. 2024 Jan;625(7993): 35-36

Muscle immune cells protect mitochondrial organelles during exercise.

Gerald Coulis, S Armando Villalta.



Keywords:  Cell biology; Immunology; Physiology

DOI:  https://doi.org/10.1038/d41586-023-03972-w
Food Res Int. 2024 Jan;pii: S0963-9969(23)01342-X. [Epub ahead of print]175 113794

Recombinant bovine FGF1 promotes muscle satellite cells mitochondrial fission and proliferation in serum-free conditions.

Qingying Liu, Lianghua Xie, Wei Chen.

  Cell cultured meat is a novel and promising technology, but developing specific culture medium for muscle cells remains one of the main technical obstacles. FGF1 signaling is reported to promote proliferation and maintain proliferative capacity of satellite cells. However, the effect of FGF1 as a supplement to serum-free medium on satellite cells in vitro culture is still unclear. In this study, an efficient method for the production of soluble and biologically active recombinant bovine FGF1 (rbFGF1) protein in Escherichia coli was established. The soluble expression level of TrxA-rbFGF1 fusion protein was 562 mg/L in shake flasks, resulting in 5.5 mg of pure rbFGF1 from 0.1 L of starting culture. In serum-free culture conditions, rbFGF1 effectively promoted the proliferation and regulated the mitochondrial morphology and function of C2C12 myoblasts.rbFGF1 activated extracellular signal-regulated kinases1/2 (ERK1/2) signaling in C2C12 myoblasts, which further stimulated dynamin related protein 1 (DRP1) Ser616 phosphorylation. These findings highlighted the potential application of rbFGF1 in developing effective serum-free medium for cultured meat production.

Keywords:  C2C12 myoblasts; Cell proliferation; Mitochondrial fission; Recombinant bovine FGF1; Serum-free medium

DOI:  https://doi.org/10.1016/j.foodres.2023.113794
Trends Endocrinol Metab. 2023 Dec 15. pii: S1043-2760(23)00243-6. [Epub ahead of print]

Mitochondrial quality control pathways sense mitochondrial protein import.

Laurie P Lee-Glover, Timothy E Shutt.

  Mitochondrial quality control (MQC) mechanisms are required to maintain a functional proteome, which enables mitochondria to perform a myriad of important cellular functions from oxidative phosphorylation to numerous other metabolic pathways. Mitochondrial protein homeostasis begins with the import of over 1000 nuclear-encoded mitochondrial proteins and the synthesis of 13 mitochondrial DNA-encoded proteins. A network of chaperones and proteases helps to fold new proteins and degrade unnecessary, damaged, or misfolded proteins, whereas more extensive damage can be removed by mitochondrial-derived vesicles (MDVs) or mitochondrial autophagy (mitophagy). Here, focusing on mechanisms in mammalian cells, we review the importance of mitochondrial protein import as a sentinel of mitochondrial function that activates multiple MQC mechanisms when impaired.

Keywords:  mitochondria; mitochondrial protein import; mitochondrial quality control; mitochondrial unfolded protein response; mitochondrial-derived vesicles; mitophagy

DOI:  https://doi.org/10.1016/j.tem.2023.11.004
Lab Invest. 2023 Dec 15. pii: S0023-6837(23)00250-7. [Epub ahead of print] 100307

The role of mitochondrial quality control in chronic obstructive pulmonary disease.

Yu-Biao Liu, Jie-Ru Hong, Nan Jiang, Ling Jin, Wen-Jing Zhong, Chen-Yu Zhang, Hui-Hui Yang, Jia-Xi Duan, Yong Zhou.

  Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity, mortality, and healthcare use worldwide with heterogeneous pathogenesis. Mitochondria, the powerhouses in cells responsible for oxidative phosphorylation and energy production, play essential roles in intracellular material metabolism, natural immunity, and cell death regulation. Therefore, it is crucial to address the urgent need for fine-tuning the regulation of mitochondrial quality to combat COPD effectively. Mitochondrial quality control (MQC) mainly refers to the selective removal of damaged or aging mitochondria and the generation of new mitochondria, which involves mitochondrial biogenesis, mitochondrial dynamics, mitophagy, etc. Mounting evidence suggests that mitochondrial dysfunction is a crucial contributor to the development and progression of COPD. This article mainly reviews the effects of MQC on COPD as well as their specific regulatory mechanisms. Finally, the therapeutic approaches of COPD via MQC are also illustrated.

Keywords:  chronic obstructive pulmonary disease; mitochondrial biogenesis; mitochondrial dynamics; mitochondrial quality control; mitophagy

DOI:  https://doi.org/10.1016/j.labinv.2023.100307
Environ Toxicol. 2023 Dec 20.

Effects of CuSO4 on hepatic mitochondrial function, biogenesis and dynamics in mice.

Yihan Wang, Yanqiu Zhu, Hengmin Cui, Huidan Deng, Zhicai Zuo, Jing Fang, Hongrui Guo.

  Copper is an essential trace element for animal. Excessive intake of copper will cause a large accumulation of copper in the body, especially in the liver, and induce hepatotoxicity, however, there are few studies on the effects of copper on hepatic mitochondrial biogenesis and mitochondrial dynamics. In this study, mice were treated with different doses of CuSO4 (0, 10, 20, and 40 mg/kg) for 21 and 42 days by gavage. The results verified that CuSO4 decreased the content of mitochondrial respiratory chain complexes I-IV in mouse liver. CuSO4 treatment resulted the decrease in the protein and mRNA expression levels of PGC-1α, TFAM, and NRF1, which were the mitochondrial biogenesis regulator proteins. Meanwhile, the proteins involved in mitochondrial fusion were reduced by CuSO4 , such as Mfn1 and Mfn2, however, mitochondrial fission proteins Drip1 and Fis1 were significantly increased. Abovementioned results show that CuSO4 could induce mitochondria damage in the liver of mice, and mitochondrial biogenesis and mitochondrial dynamics are involved in the molecular mechanism of CuSO4 -induced hepatotoxicity.

Keywords:  copper; liver; mitochondria; mitochondrial biogenesis; mitochondrial dynamics

DOI:  https://doi.org/10.1002/tox.24085
Redox Biol. 2023 Dec 12. pii: S2213-2317(23)00397-X. [Epub ahead of print]69 102996

Phosphatidate phosphatase Lipin1 involves in diabetic encephalopathy pathogenesis via regulating synaptic mitochondrial dynamics.

Xiaolin Han, Shan Huang, Ziyun Zhuang, Xiaochen Zhang, Min Xie, Nengjun Lou, Mengyu Hua, Xianghua Zhuang, Shuyan Yu, Shihong Chen.

  Diabetic encephalopathy (DE) is a common central nervous system complication of diabetes mellitus without effective therapy currently. Recent studies have highlighted synaptic mitochondrial damages as a possible pathological basis for DE, but the underlying mechanisms remain unclear. Our previous work has revealed that phosphatidate phosphatase Lipin1, a critical enzyme involved with phospholipid synthesis, is closely related to the pathogenesis of DE. Here, we demonstrate that Lipin1 is significantly down-regulated in rat hippocampus of DE. Knock-down of Lipin1 within hippocampus of normal rats induces dysregulation of homeostasis in synaptic mitochondrial dynamics with an increase of mitochondrial fission and a decrease of fusion, then causes synaptic mitochondrial dysfunction, synaptic plasticity deficits as well as cognitive impairments, similar to that observed in response to chronic hyperglycemia exposure. In contrast, an up-regulation of Lipin1 within hippocampus in the DE model ameliorates this cascade of dysfunction. We also find that the effect of Lipin1 that regulating mitochondrial dynamics results from maintaining appropriate phospholipid components in the mitochondrial membrane. In conclusion, alterations in hippocampal Lipin1 contribute to hippocampal synaptic mitochondrial dysfunction and cognitive deficits observed in DE. Targeting Lipin1 might be a potential therapeutic strategy for the clinical treatment of DE.

Keywords:  Cognitive dysfunction; Diabetic encephalopathy; Lipin1; Phospholipids; Synaptic mitochondrial dynamics; Synaptic plasticity

DOI:  https://doi.org/10.1016/j.redox.2023.102996
Nature. 2023 Dec 20.

Mitochondrial dysfunction abrogates dietary lipid processing in enterocytes.

Chrysanthi Moschandrea, Vangelis Kondylis, Ioannis Evangelakos, Marija Herholz, Farina Schneider, Christina Schmidt, Ming Yang, Sandra Ehret, Markus Heine, Michelle Y Jaeckstein, Karolina Szczepanowska, Robin Schwarzer, Linda Baumann, Theresa Bock, Efterpi Nikitopoulou, Susanne Brodesser, Marcus Krüger, Christian Frezza, Joerg Heeren, Aleksandra Trifunovic, Manolis Pasparakis.

Digested dietary fats are taken up by enterocytes where they are assembled into pre-chylomicrons in the endoplasmic reticulum followed by transport to the Golgi for maturation and subsequent secretion to the circulation1. The role of mitochondria in dietary lipid processing is unclear. Here we show that mitochondrial dysfunction in enterocytes inhibits chylomicron production and the transport of dietary lipids to peripheral organs. Mice with specific ablation of the mitochondrial aspartyl-tRNA synthetase DARS2 (ref. 2), the respiratory chain subunit SDHA3 or the assembly factor COX10 (ref. 4) in intestinal epithelial cells showed accumulation of large lipid droplets (LDs) in enterocytes of the proximal small intestine and failed to thrive. Feeding a fat-free diet suppressed the build-up of LDs in DARS2-deficient enterocytes, which shows that the accumulating lipids derive mostly from digested fat. Furthermore, metabolic tracing studies revealed an impaired transport of dietary lipids to peripheral organs in mice lacking DARS2 in intestinal epithelial cells. DARS2 deficiency caused a distinct lack of mature chylomicrons concomitant with a progressive dispersal of the Golgi apparatus in proximal enterocytes. This finding suggests that mitochondrial dysfunction results in impaired trafficking of chylomicrons from the endoplasmic reticulum to the Golgi, which in turn leads to storage of dietary lipids in large cytoplasmic LDs. Taken together, these results reveal a role for mitochondria in dietary lipid transport in enterocytes, which might be relevant for understanding the intestinal defects observed in patients with mitochondrial disorders5.

DOI: https://doi.org/10.1038/s41586-023-06857-0
bioRxiv. 2023 Dec 05. pii: 2023.12.05.570104. [Epub ahead of print]

Mitochondrial network reorganization and transient expansion during oligodendrocyte generation.

Xhoela Bame, Robert A Hill.

Oligodendrocyte precursor cells (OPCs) give rise to myelinating oligodendrocytes of the central nervous system. This process persists throughout life and is essential for recovery from neurodegeneration. To better understand the cellular checkpoints that occur during oligodendrogenesis, we determined the mitochondrial distribution and morphometrics across the oligodendrocyte lineage in mouse and human cerebral cortex. During oligodendrocyte generation, mitochondrial content expanded concurrently with a change in subcellular partitioning towards the distal processes. These changes were followed by an abrupt loss of mitochondria in the oligodendrocyte processes and myelin, coinciding with sheath compaction. This reorganization and extensive expansion and depletion took 3 days. Oligodendrocyte mitochondria were stationary over days while OPC mitochondrial motility was modulated by animal arousal state within minutes. Aged OPCs also displayed decreased mitochondrial size, content, and motility. Thus, mitochondrial dynamics are linked to oligodendrocyte generation, dynamically modified by their local microenvironment, and altered in the aging brain.

DOI: https://doi.org/10.1101/2023.12.05.570104
FASEB J. 2024 Jan;38(1): e23379

Dynamin-related protein 1 is a critical regulator of mitochondrial calcium homeostasis during myocardial ischemia/reperfusion injury.

Lin Piao, Yong-Hu Fang, Michael Fisher, Robert B Hamanaka, Alaa Ousta, Rongxu Wu, Gökhan M Mutlu, Alfredo J Garcia, Stephen L Archer, Willard W Sharp.

Dynamin-related protein 1 (Drp1) is a cytosolic GTPase protein that when activated translocates to the mitochondria, meditating mitochondrial fission and increasing reactive oxygen species (ROS) in cardiomyocytes. Drp1 has shown promise as a therapeutic target for reducing cardiac ischemia/reperfusion (IR) injury; however, the lack of specificity of some small molecule Drp1 inhibitors and the reliance on the use of Drp1 haploinsufficient hearts from older mice have left the role of Drp1 in IR in question. Here, we address these concerns using two approaches, using: (a) short-term (3 weeks), conditional, cardiomyocyte-specific, Drp1 knockout (KO) and (b) a novel, highly specific Drp1 GTPase inhibitor, Drpitor1a. Short-term Drp1 KO mice exhibited preserved exercise capacity and cardiac contractility, and their isolated cardiac mitochondria demonstrated increased mitochondrial complex 1 activity, respiratory coupling, and calcium retention capacity compared to controls. When exposed to IR injury in a Langendorff perfusion system, Drp1 KO hearts had preserved contractility, decreased reactive oxygen species (ROS), enhanced mitochondrial calcium capacity, and increased resistance to mitochondrial permeability transition pore (MPTP) opening. Pharmacological inhibition of Drp1 with Drpitor1a following ischemia, but before reperfusion, was as protective as Drp1 KO for cardiac function and mitochondrial calcium homeostasis. In contrast to the benefits of short-term Drp1 inhibition, prolonged Drp1 ablation (6 weeks) resulted in cardiomyopathy. Drp1 KO hearts were also associated with decreased ryanodine receptor 2 (RyR2) protein expression and pharmacological inhibition of the RyR2 receptor decreased ROS in post-IR hearts suggesting that changes in RyR2 may have a role in Drp1 KO mediated cardioprotection. We conclude that Drp1-mediated increases in myocardial ROS production and impairment of mitochondrial calcium handling are key mechanisms of IR injury. Short-term inhibition of Drp1 is a promising strategy to limit early myocardial IR injury which is relevant for the therapy of acute myocardial infarction, cardiac arrest, and heart transplantation.

DOI: https://doi.org/10.1096/fj.202301040RR
Nanoscale Adv. 2023 Dec 19. 6(1): 209-220

Confinement primes cells for faster migration by polarizing active mitochondria.

Jenna A Mosier, Emily D Fabiano, Catherine M Ludolph, Addison E White, Cynthia A Reinhart-King.

Mechanical cues in the tumor microenvironment interplay with internal cellular processes to control cancer cell migration. Microscale pores present in tumor tissue confer varying degrees of confinement on migrating cells, increasing matrix contact and inducing cytoskeletal rearrangement. Previously, we observed that increased collagen matrix contact significantly increased cell migration speed and cell-induced strains within the matrix. However, the effects of this confinement on future cell migration are not fully understood. Here, we use a collagen microtrack platform to determine the effect of confinement on priming MDA-MB-231 cancer cells for fast migration. We show that migration through a confined track results in increased speed and accumulation of migratory machinery, including actin and active mitochondria, in the front of migrating breast cancer cells. By designing microtracks that allow cells to first navigate a region of high confinement, then a region of low confinement, we assessed whether migration in high confinement changes future migratory behavior. Indeed, cells maintain their speed attained in high confinement even after exiting to a region of low confinement, indicating that cells maintain memory of previous matrix cues to fuel fast migration. Active mitochondria maintain their location at the front of the cell even after cells leave high confinement. Furthermore, knocking out vinculin to disrupt focal adhesions disrupts active mitochondrial localization and disrupts the fast migration seen upon release from confinement. Together, these data suggest that active mitochondrial localization in confinement may facilitate fast migration post-confinement. By better understanding how confinement contributes to future cancer cell migration, we can identify potential therapeutic targets to inhibit breast cancer metastasis.

DOI: https://doi.org/10.1039/d3na00478c
Sci Rep. 2023 Dec 20. 13(1): 22782

Inhibition of Drp1 orchestrates the responsiveness of breast cancer cells to paclitaxel but insignificantly relieves paclitaxel-related ovarian damage in mice.

Adel I Alalawy, Mohamed Sakran, Fahad M Alzuaibr, Maeidh A Alotaibi, Mohamed E El-Hefnawy, Abdulelah Y Hazazi, Saad M El-Gendy, Esraa A Aidy, Heba E Abdelaziz, Doha F Ismail, Mohamed Hessien.

Chemoresistance and chemotherapy-related ovarian damage are well-reported in breast cancer (BC) young patients. Herein, the inhibition of the mitochondrial fission was invested to explore its chemosensitizing role in Paclitaxel (PTX)-resistant cells, and its ability to restore the ovarian integrity in mice receiving PTX or cisplatin chemotherapy. To establish these aims, PTX-resistance was generated in BC cells, which were treated with PTX in combination with Drp1 deficiency, via mdivi-1, or Drp1-specific siRNA transfection. Furthermore, the alterations in the ovarian structure and the endocrine-related hormones were explored in mice receiving repetitive doses of PTX or cisplatin. We found that combining PTX with mdivi-1 improved cell responsiveness to PTX, induced apoptosis- and autophagy-mediated cell death, and relieved cellular oxidative stress. Additionally, the expression of PCNA1 and cyclin B1 genes were downregulated, meanwhile, p53, p21, and mitochondrial fusion proteins (Mfu1&Mfu2) were increased. The in vivo investigations in mice demonstrated that PTX induced gonadotoxic damage similar to cisplatin, whereas dual treatment of mice with PTX+ mdivi-1 failed to restore their normal follicular count and the circulating levels of E2 and AMH hormones. These results suggested that combining Drp1 inhibition with PTX resensitized breast cancer cells to PTX but failed to offer enough protection against chemotherapy-related gonadotoxicity.

DOI: https://doi.org/10.1038/s41598-023-49578-0
Biochim Biophys Acta Bioenerg. 2023 Dec 16. pii: S0005-2728(23)00073-7. [Epub ahead of print] 149027

Performance of TMRM and Mitotrackers in mitochondrial morphofunctional analysis of primary human skin fibroblasts.

Shruti Desai, Sander Grefte, Els van de Westerlo, Susette Lauwen, Angela Paters, Jochen H M Prehn, Zhuohui Gan, Jaap Keijer, Merel J W Adjobo-Hermans, Werner J H Koopman.

  Mitochondrial membrane potential (Δψ) and morphology are considered key readouts of mitochondrial functional state. This morphofunction can be studied using fluorescent dyes ("probes") like tetramethylrhodamine methyl ester (TMRM) and Mitotracker (MT) dyes. Although these dyes are broadly used, information comparing their performance in mitochondrial morphology quantification and Δψ-sensitivity in the same cell model is still scarce. Here we applied epifluorescence microscopy of primary human skin fibroblasts to evaluate TMRM, Mitotracker Red CMXros (CMXros), Mitotracker Red CMH2Xros (CMH2Xros), Mitotracker Green FM (MG) and Mitotracker Deep Red FM (MDR). All probes were suited for automated quantification of mitochondrial morphology parameters when Δψ was normal, although they did not deliver quantitatively identical results. The mitochondrial localization of TMRM and MTs was differentially sensitive to carbonyl cyanide-4-phenylhydrazone (FCCP)-induced Δψ depolarization, decreasing in the order: TMRM ≫ CHM2Xros = CMXros = MDR > MG. To study the effect of reversible Δψ changes, the impact of photo-induced Δψ "flickering" was studied in cells co-stained with TMRM and MG. During a flickering event, individual mitochondria displayed subsequent TMRM release and uptake, whereas this phenomenon was not observed for MG. Spatiotemporal and computational analysis of the flickering event provided evidence that TMRM redistributes between adjacent mitochondria by a mechanism dependent on Δψ and TMRM concentration. In summary, this study demonstrates that: (1) TMRM and MTs are suited for automated mitochondrial morphology quantification, (2) numerical data obtained with different probes is not identical, and (3) all probes are sensitive to FCCP-induced Δψ depolarization, with TMRM and MG displaying the highest and lowest sensitivity, respectively. We conclude that TMRM is better suited for integrated analysis of Δψ and mitochondrial morphology than the tested MTs under conditions that Δψ is not substantially depolarized.

Keywords:  FCCP; Flickering; Mitochondrial morphology; Mitotracker; TMRM

DOI:  https://doi.org/10.1016/j.bbabio.2023.149027
J Vis Exp. 2023 Dec 01.

Analysis of the Mitochondrial Density and Longitudinal Distribution in Rat Live-Skeletal Muscle Fibers by Confocal Microscopy.

Perla Pérez-Treviño, Bianca Nieblas, Selma Romina López-Vaquera, Noemí García.

The mitochondrion is an organelle that can be elongated, fragmented, and renovated according to the metabolic requirements of the cells. The remodeling of the mitochondrial network allows healthy mitochondria to meet cellular demands; however, the loss of this capacity has been related to the development or progression of different pathologies. In skeletal muscle, mitochondrial density and distribution changes are observed in physiological and pathological conditions such as exercise, aging, and obesity, among others. Therefore, the study of the mitochondrial network may provide a better understanding of mechanisms related to those conditions. Here, a protocol for mitochondria imaging of live-skeletal muscle fibers from rats is described. Fibers are manually dissected in a relaxing solution and incubated with a fluorescent live-cell imaging indicator of mitochondria (tetramethylrhodamine ethyl ester, TMRE). The mitochondria signal is recorded by confocal microscopy using the XYZ scan mode to obtain confocal images of the intermyofibrillar mitochondrial (IMF) network. After that, the confocal images are processed by thresholding and binarization. The binarized confocal image accounts for the positive pixels for mitochondria, which are then counted to obtain the mitochondrial density. The mitochondrial network in skeletal muscle is characterized by a high density of IMF population, which has a periodic longitudinal distribution similar to that of T-tubules (TT). The Fast Fourier Transform (FFT) is a standard analysis technique performed to evaluate the distribution of TT that allows finding the distribution frequency and the level of their organization. In this protocol, the implementation of the FFT algorithm is described for the analysis of the longitudinal mitochondrial distribution in skeletal muscle.

DOI: https://doi.org/10.3791/65306
Biochemistry (Mosc). 2023 Oct;88(10): 1596-1607

Mitochondrial Network: Electric Cable and More.

Polina A Abramicheva, Nadezda V Andrianova, Valentina A Babenko, Ljubava D Zorova, Savva D Zorov, Irina B Pevzner, Vasily A Popkov, Dmitry S Semenovich, Elmira I Yakupova, Denis N Silachev, Egor Y Plotnikov, Gennady T Sukhikh, Dmitry B Zorov.

  Mitochondria in a cell can unite and organize complex, extended structures that occupy the entire cellular volume, providing an equal supply with energy in the form of ATP synthesized in mitochondria. In accordance with the chemiosmotic concept, the oxidation energy of respiratory substrates is largely stored in the form of an electrical potential difference on the inner membrane of mitochondria. The theory of the functioning of extended mitochondrial structures as intracellular electrical wires suggests that mitochondria provide the fastest delivery of electrical energy through the cellular volume, followed by the use of this energy for the synthesis of ATP, thereby accelerating the process of ATP delivery compared to the rather slow diffusion of ATP in the cell. This analytical review gives the history of the cable theory, lists unsolved critical problems, describes the restructuring of the mitochondrial network and the role of oxidative stress in this process. In addition to the already proven functioning of extended mitochondrial structures as electrical cables, a number of additional functions are proposed, in particular, the hypothesis is put forth that mitochondrial networks maintain the redox potential in the cellular volume, which may vary depending on the physiological state, as a result of changes in the three-dimensional organization of the mitochondrial network (fragmentation/fission-fusion). A number of pathologies accompanied by a violation of the redox status and the participation of mitochondria in them are considered.

Keywords:  cardiomyocytes; electricity; fetal growth retardation; fission; fragmentation; membrane potential; mitochondria; network; oxidative stress; preeclampsia; redox; reticulum; spermatozoa

DOI:  https://doi.org/10.1134/S0006297923100140
J Environ Sci (China). 2024 Apr;pii: S1001-0742(23)00120-1. [Epub ahead of print]138 288-300

Regulation of PM2.5 on mitochondrial damage in H9c2 cells through miR-421/SIRT3 pathway and protective effect of miR-421 inhibitor and resveratrol.

Shanshan Chen, Wenqi Chen, Zhiping Li, Jianwei Yue, Ken Kin Lam Yung, Ruijin Li.

  Fine particulate matter (PM2.5) exposure is associated with cardiovascular disease (CVD) morbidity and mortality. Mitochondria are sensitive targets of PM2.5, and mitochondrial dysfunction is closely related to the occurrence of CVD. The epigenetic mechanism of PM2.5-triggered mitochondrial injury of cardiomyocytes is unclear. This study focused on the miR-421/SIRT3 signaling pathway to investigate the regulatory mechanism in cardiac mitochondrial dynamics imbalance in rat H9c2 cells induced by PM2.5. Results illustrated that PM2.5 impaired mitochondrial function and caused dynamics homeostasis imbalance. Besides, PM2.5 up-regulated miR-421 and down-regulated SIRT3 gene expression, along with decreasing p-FOXO3a (SIRT3 downstream target gene) and p-Parkin expression and triggering abnormal expression of fusion gene OPA1 and fission gene Drp1. Further, miR-421 inhibitor (miR-421i) and resveratrol significantly elevated the SIRT3 levels in H9c2 cells after PM2.5 exposure and mediated the expression of SOD2, OPA1 and Drp1, restoring the mitochondrial morphology and function. It suggests that miR-421/SIRT3 pathway plays an epigenetic regulatory role in mitochondrial damage induced by PM2.5 and that miR-421i and resveratrol exert protective effects against PM2.5-incurred cardiotoxicity.

Keywords:  Fine particulate matter; MiR-421; Mitochondrial damage; Rat H9c2 cells; Resveratrol; SIRT3

DOI:  https://doi.org/10.1016/j.jes.2023.03.016
Respir Res. 2023 Dec 18. 24(1): 319

Role of mitochondrial fusion proteins MFN2 and OPA1 on lung cellular senescence in chronic obstructive pulmonary disease.

Chenfei Li, Qi Liu, Qing Chang, Meiqin Xie, Jiali Weng, Xiaohui Wang, Mengnan Li, Jiani Chen, Yan Huang, Xiaohua Yang, Kai Wang, Na Zhang, Kian Fan Chung, Ian M Adcock, Hai Zhang, Feng Li.

   BACKGROUND: Mitochondrial dysfunction and lung cellular senescence are significant features involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). Cigarette smoke (CS) stands as the primary contributing factor to COPD. This study examined mitochondrial dynamics, mitophagy and lung cellular senescence in COPD patients and investigated the effects of modulation of mitochondrial fusion [mitofusin2 (MFN2) and Optic atrophy 1 (OPA1)] on CS extract (CSE)-induced lung cellular senescence.
METHODS: Senescence-associated secretory phenotype (SASP) component mRNAs (IL-1β, IL-6, CXCL1 and CXCL8), mitochondrial morphology, mitophagy and mitochondria-related proteins (including phosphorylated-DRP1(p-DRP1), DRP1, MFF, MNF2, OPA1, PINK1, PARK2, SQSTM1/p62 and LC3b) and senescence-related proteins (including P16, H2A.X and Klotho) were measured in lung tissues or primary alveolar type II (ATII) cells of non-smokers, smokers and COPD patients. Alveolar epithelial (A549) cells were exposed to CSE with either pharmacologic inducer (leflunomide and BGP15) or genetic induction of MFN2 and OPA1 respectively.
RESULTS: There were increases in mitochondrial number, and decreases in mitochondrial size and activity in lung tissues from COPD patients. SASP-related mRNAs, DRP1 phosphorylation, DRP1, MFF, PARK2, SQSTM1/p62, LC3B II/LC3B I, P16 and H2A.X protein levels were increased, while MFN2, OPA1, PINK1 and Klotho protein levels were decreased in lung tissues from COPD patients. Some similar results were identified in primary ATII cells of COPD patients. CSE induced increases in oxidative stress, SASP-related mRNAs, mitochondrial damage and dysfunction, mitophagy and cellular senescence in A549 cells, which were ameliorated by both pharmacological inducers and genetic overexpression of MFN2 and OPA1.
CONCLUSIONS: Impaired mitochondrial fusion, enhanced mitophagy and lung cellular senescence are observed in the lung of COPD patients. Up-regulation of MFN2 and OPA1 attenuates oxidative stress, mitophagy and lung cellular senescence, offering potential innovative therapeutic targets for COPD therapy.

Keywords:  Chronic obstructive pulmonary disease (COPD); Cigarette smoke; Lung senescence; Mitochondrial dynamics; Mitophagy

DOI:  https://doi.org/10.1186/s12931-023-02634-9
Biochemistry (Mosc). 2023 Nov;88(11): 1832-1843

Diversity and Evolution of Mitochondrial Translation Apparatus.

Mariya V Baleva, Ulyana E Piunova, Ivan V Chicherin, Sergey A Levitskii, Piotr A Kamenski.

  The evolution of mitochondria has proceeded independently in different eukaryotic lines, which is reflected in the diversity of mitochondrial genomes and mechanisms of their expression in eukaryotic species. Mitochondria have lost most of bacterial ancestor genes by transferring them to the nucleus or eliminating them. However, mitochondria of almost all eukaryotic cells still retain relatively small genomes, as well as their replication, transcription, and translation apparatuses. The dependence on the nuclear genome, specific features of mitochondrial transcripts, and synthesis of highly hydrophobic membrane proteins in the mitochondria have led to significant changes in the translation apparatus inherited from the bacterial ancestor, which retained the basic structure necessary for protein synthesis but became more specialized and labile. In this review, we discuss specific properties of translation initiation in the mitochondria and how the evolution of mitochondria affected the functions of main factors initiating protein biosynthesis in these organelles.

Keywords:  mitochondria; regulation of translation; translation; translation initiation factors

DOI:  https://doi.org/10.1134/S0006297923110135
Phytomedicine. 2023 Dec 02. pii: S0944-7113(23)00606-2. [Epub ahead of print]123 155247

Modified Hu-lu-ba-wan protects diabetic glomerular podocytes via promoting PKM2-mediated mitochondrial dynamic homeostasis.

Minmin Gong, Yujin Guo, Hui Dong, Fan Wu, Qiongyao He, Jing Gong, Fuer Lu.

   BACKGROUND: Mitochondrial dysfunction is implicated in the progression of diabetic kidney disease (DKD). Damaged mitochondria produce excessive reactive oxygen species (ROS) that can cause apoptosis. Mitochondrial dynamics control the quality and function of mitochondria. Targeting mitochondrial dynamics may reduce ROS-induced apoptosis and improve renal injury in DKD. Modified Hu-lu-ba-wan (MHLBW) shows distinct clinical effects on DKD patients, which are related to its role in antioxidant stress modulation. However, the relevant mechanisms of MHLBW have not been clearly explored.
PURPOSE: This study was aimed to evaluate the therapeutic effects of MHLBW on spontaneous DKD mice and clarify the potential mechanisms.
METHODS: The main components of MHLBW were identified by HPLC. Using db/db mice as DKD models, we evaluated the therapeutic effects of MHLBW on mice after an 8-week administration. We investigated the molecular mechanism of MHLBW in regulating mitochondrial dynamic homeostasis, podocyte apoptosis, and glomerular damage. After that, computational docking analysis and in vitro experiments were conducted for further mechanism verification.
RESULTS: Intragastric administration of MHLBW for 8 weeks in db/db mice significantly improved glucose metabolism, basement membrane thickening, mesangial expansion, glomerular fibrosis, and podocyte injury. MHLBW can reverse podocyte apoptosis via promoting mitochondrial dynamic homeostasis, which was related to regulating the PKM2/ PGC-1α/Opa1 pathway. Berberine (BBR), one of the components of MHLBW, exhibited preeminent affinity with PKM2 as reflected by computational docking analysis. In cultured podocytes, BBR can also prevent apoptosis by promoting PKM2-mediated mitochondrial dynamic homeostasis.
CONCLUSION: Our study demonstrates that MHLBW can treat DKD by inhibiting glomerular damage and podocyte apoptosis through positive regulation of PKM2-mediated mitochondrial dynamic homeostasis. These results may provide a potential strategy against DKD.

Keywords:  Diabetic kidney disease; Mitochondrial dynamic homeostasis; Modified Hu-lu-ba-wan; PKM2; Podocyte

DOI:  https://doi.org/10.1016/j.phymed.2023.155247
Nat Commun. 2023 Dec 20. 14(1): 8474

Mtfp1 ablation enhances mitochondrial respiration and protects against hepatic steatosis.

Cecilia Patitucci, Juan Diego Hernández-Camacho, Elodie Vimont, Sonny Yde, Thomas Cokelaer, Thibault Chaze, Quentin Giai Gianetto, Mariette Matondo, Anastasia Gazi, Ivan Nemazanyy, David A Stroud, Daniella H Hock, Erminia Donnarumma, Timothy Wai.

Hepatic steatosis is the result of imbalanced nutrient delivery and metabolism in the liver and is the first hallmark of Metabolic dysfunction-associated steatotic liver disease (MASLD). MASLD is the most common chronic liver disease and involves the accumulation of excess lipids in hepatocytes, inflammation, and cancer. Mitochondria play central roles in liver metabolism yet the specific mitochondrial functions causally linked to MASLD remain unclear. Here, we identify Mitochondrial Fission Process 1 protein (MTFP1) as a key regulator of mitochondrial and metabolic activity in the liver. Deletion of Mtfp1 in hepatocytes is physiologically benign in mice yet leads to the upregulation of oxidative phosphorylation (OXPHOS) activity and mitochondrial respiration, independently of mitochondrial biogenesis. Consequently, liver-specific knockout mice are protected against high fat diet-induced steatosis and metabolic dysregulation. Additionally, Mtfp1 deletion inhibits mitochondrial permeability transition pore opening in hepatocytes, conferring protection against apoptotic liver damage in vivo and ex vivo. Our work uncovers additional functions of MTFP1 in the liver, positioning this gene as an unexpected regulator of OXPHOS and a therapeutic candidate for MASLD.

DOI: https://doi.org/10.1038/s41467-023-44143-9
bioRxiv. 2023 Dec 10. pii: 2023.12.09.569632. [Epub ahead of print]

Post-Transcriptional Methylation of Mitochondrial-tRNA Differentially Contributes to Mitochondrial Pathology.

Sunita Maharjan, Howard Gamper, Yuka Yamaki, Robert Y Henley, Nan-Sheng Li, Takeo Suzuki, Tsutomu Suzuki, Joseph A Piccirilli, Meni Wanunu, Erin Seifert, Douglas C Wallace, Ya-Ming Hou.

Human mitochondrial tRNAs (mt-tRNAs), critical for mitochondrial biogenesis, are frequently associated with pathogenic mutations. These mt-tRNAs have unusual sequence motifs and require post-transcriptional modifications to stabilize their fragile structures. However, whether a modification that stabilizes a wild-type (WT) mt-tRNA structure would also stabilize its pathogenic variants is unknown. Here we show that the N 1 -methylation of guanosine at position 9 (m 1 G9) of mt-Leu(UAA), while stabilizing the WT tRNA, has an opposite and destabilizing effect on variants associated with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes). This differential effect is further demonstrated by the observation that demethylation of m 1 G9, while damaging to the WT tRNA, is beneficial to the major pathogenic variant, improving its structure and activity. These results have new therapeutic implications, suggesting that the N 1 -methylation of mt-tRNAs at position 9 is a determinant of pathogenicity and that controlling the methylation level is an important modulator of mt-tRNA-associated diseases.

DOI: https://doi.org/10.1101/2023.12.09.569632
Nat Cell Biol. 2023 Dec 21.

Quantitative subcellular reconstruction reveals a lipid mediated inter-organelle biogenesis network.

Richard G Lee, Danielle L Rudler, Samuel A Raven, Liuyu Peng, Anaëlle Chopin, Edward S X Moh, Tim McCubbin, Stefan J Siira, Samuel V Fagan, Nicholas J DeBono, Maike Stentenbach, Jasmin Browne, Filip F Rackham, Ji Li, Kaylene J Simpson, Esteban Marcellin, Nicolle H Packer, Gavin E Reid, Benjamin S Padman, Oliver Rackham, Aleksandra Filipovska.

The structures and functions of organelles in cells depend on each other but have not been systematically explored. We established stable knockout cell lines of peroxisomal, Golgi and endoplasmic reticulum genes identified in a whole-genome CRISPR knockout screen for inducers of mitochondrial biogenesis stress, showing that defects in peroxisome, Golgi and endoplasmic reticulum metabolism disrupt mitochondrial structure and function. Our quantitative total-organelle profiling approach for focussed ion beam scanning electron microscopy revealed in unprecedented detail that specific organelle dysfunctions precipitate multi-organelle biogenesis defects, impair mitochondrial morphology and reduce respiration. Multi-omics profiling showed a unified proteome response and global shifts in lipid and glycoprotein homeostasis that are elicited when organelle biogenesis is compromised, and that the resulting mitochondrial dysfunction can be rescued with precursors for ether-glycerophospholipid metabolic pathways. This work defines metabolic and morphological interactions between organelles and how their perturbation can cause disease.

DOI: https://doi.org/10.1038/s41556-023-01297-4
Int J Mol Sci. 2023 Dec 15. pii: 17533. [Epub ahead of print]24(24):

Novel Relationship between Mitofusin 2-Mediated Mitochondrial Hyperfusion, Metabolic Remodeling, and Glycolysis in Pulmonary Arterial Endothelial Cells.

Manivannan Yegambaram, Xutong Sun, Alejandro Garcia Flores, Qing Lu, Jamie Soto, Jaime Richards, Saurabh Aggarwal, Ting Wang, Haiwei Gu, Jeffrey R Fineman, Stephen M Black.

  The disruption of mitochondrial dynamics has been identified in cardiovascular diseases, including pulmonary hypertension (PH), ischemia-reperfusion injury, heart failure, and cardiomyopathy. Mitofusin 2 (Mfn2) is abundantly expressed in heart and pulmonary vasculature cells at the outer mitochondrial membrane to modulate fusion. Previously, we have reported reduced levels of Mfn2 and fragmented mitochondria in pulmonary arterial endothelial cells (PAECs) isolated from a sheep model of PH induced by pulmonary over-circulation and restoring Mfn2 normalized mitochondrial function. In this study, we assessed the effect of increased expression of Mfn2 on mitochondrial metabolism, bioenergetics, reactive oxygen species production, and mitochondrial membrane potential in control PAECs. Using an adenoviral expression system to overexpress Mfn2 in PAECs and utilizing 13C labeled substrates, we assessed the levels of TCA cycle metabolites. We identified increased pyruvate and lactate production in cells, revealing a glycolytic phenotype (Warburg phenotype). Mfn2 overexpression decreased the mitochondrial ATP production rate, increased the rate of glycolytic ATP production, and disrupted mitochondrial bioenergetics. The increase in glycolysis was linked to increased hypoxia-inducible factor 1α (HIF-1α) protein levels, elevated mitochondrial reactive oxygen species (mt-ROS), and decreased mitochondrial membrane potential. Our data suggest that disrupting the mitochondrial fusion/fission balance to favor hyperfusion leads to a metabolic shift that promotes aerobic glycolysis. Thus, therapies designed to increase mitochondrial fusion should be approached with caution.

Keywords:  glycolysis; metabolomics; mitochondrial function; mitofusin; pulmonary hypertension

DOI:  https://doi.org/10.3390/ijms242417533
Biomed Pharmacother. 2023 Dec 20. pii: S0753-3322(23)01808-5. [Epub ahead of print]170 116010

A gold-based inhibitor of oxidative phosphorylation is effective against triple negative breast cancer.

R Tyler Mertens, Jong Hyun Kim, Samuel Ofori, Chibuzor Olelewe, Paul J Kamitsuka, Gunnar F Kwakye, Samuel G Awuah.

  Triple-negative breast cancer (TNBC) is associated with metabolic heterogeneity and poor prognosis with limited treatment options. New treatment paradigms for TNBC remains an unmet need. Thus, therapeutics that target metabolism are particularly attractive approaches. We previously designed organometallic Au(III) compounds capable of modulating mitochondrial respiration by ligand tuning with high anticancer potency in vitro and in vivo. Here, we show that an efficacious Au(III) dithiocarbamate (AuDTC) compound induce mitochondrial dysfunction and oxidative damage in cancer cells. Efficacy of AuDTC in TNBC mouse models harboring mitochondrial oxidative phosphorylation (OXPHOS) dependence and metabolic heterogeneity establishes its therapeutic potential following systemic delivery. This provides evidence that AuDTC is an effective modulator of mitochondrial respiration worthy of clinical development in the context of TNBC. ONE SENTENCE SUMMARY: Metabolic-targeting of triple-negative breast cancer by gold anticancer agent may provide efficacious therapy.

Keywords:  Gold; Mitochondria; OXPHOS; Triple negative breast cancer

DOI:  https://doi.org/10.1016/j.biopha.2023.116010
Front Plant Sci. 2023 ;14 1283292

Intrageneric structural variation in organelle genomes from the genus Dystaenia (Apiaceae): genome rearrangement and mitochondrion-to-plastid DNA transfer.

Seongjun Park, SeonJoo Park.

   Introduction: During plant evolution, intracellular DNA transfer (IDT) occurs not only from organelles to the nucleus but also between organelles. To further comprehend these events, both organelle genomes and transcriptomes are needed.
Methods: In this study, we constructed organelle genomes and transcriptomes for two Dystaenia species and described their dynamic IDTs between their nuclear and mitochondrial genomes, or plastid and mitochondrial genomes (plastome and mitogenome).
Results and Discussion: We identified the putative functional transfers of the mitochondrial genes 5' rpl2, rps10, rps14, rps19, and sdh3 to the nucleus in both Dystaenia species and detected two transcripts for the rpl2 and sdh3 genes. Additional transcriptomes from the Apicaceae species also provided evidence for the transfers and duplications of these mitochondrial genes, showing lineage-specific patterns. Intrageneric variations of the IDT were found between the Dystaenia organelle genomes. Recurrent plastid-to-mitochondrion DNA transfer events were only identified in the D. takeshimana mitogenome, and a pair of mitochondrial DNAs of plastid origin (MIPTs) may generate minor alternative isoforms. We only found a mitochondrion-to-plastid DNA transfer event in the D. ibukiensis plastome. This event may be linked to inverted repeat boundary shifts in its plastome. We inferred that the insertion region involved an MIPT that had already acquired a plastid sequence in its mitogenome via IDT. We propose that the MIPT acts as a homologous region pairing between the donor and recipient sequences. Our results provide insight into the evolution of organelle genomes across the family Apiaceae.

Keywords:  gene duplication; intracellular transfer; inversion; mitochondrial genome; plastid genome

DOI:  https://doi.org/10.3389/fpls.2023.1283292
Small. 2023 Dec 18. e2308621

A D-Y Shaped Neuropeptide Y Mimetic Peptide-Dye Self-Assembly with Maximal Emission Beyond 1300 nm and Glioma Mitochondrial Activity Modulation.

Yanying Li, Xuelu He, Pin Wang, Bo Yuan, Yuanbo Pan, Xueyin Hu, Liheng Lu, Aiguo Wu, Juan Li.

  Neuropeptide Y (NPY), as one of the most abundant neuropeptides known, is widely distributed in the central and peripheral nervous system. However, most of the reported NPY-mimetic peptides are hard to cross the blood-brain barrier, target glioma mitochondria, and achieve self-assembly nanostructure in situ. Here, based on the α-helix structure of the novel chiral NPY-mimetic peptides D/L NPY(14), a Y-shaped peptide is designed with the sequences that can be recognized by enterokinase and achieved nanofibers conversion in glioma cell mitochondria. Coupling the Y-shaped NPY-mimetic peptide with the NIR-II fluorophore IR1048, a red-shifting of the fluorescence spectrum beyond 1300 nm is achieved through self-assembly. After the self-assembly in glioma mitochondria, the formed nanofibers can promote intracellular mitochondrial ROS production and extend the NIR-II fluorescence imaging time to at least 7 days in vivo. This work for the first time endows the self-assembly of α-helical-based chiral NPY-mimetic peptides, providing a novel strategy for glioma subcellular regulation enhanced antitumor treatment guided by NIR-II fluorescence imaging.

Keywords:  NIR-II imaging; Y1 receptor; d-peptide ligand; neuropeptide Y; self-assembly

DOI:  https://doi.org/10.1002/smll.202308621
Open Biol. 2023 Dec;13(12): 230181

Mitochondrial replication's role in vertebrate mtDNA strand asymmetry.

André Gomes-Dos-Santos, Nair Vilas-Arrondo, André M Machado, Esther Román-Marcote, Jose Luís Del Río Iglesias, Francisco Baldó, Montse Pérez, Miguel M Fonseca, L Filipe C Castro, Elsa Froufe.

  Mitogenomes are defined as compact and structurally stable over aeons. This perception results from a vertebrate-centric vision, where few types of mtDNA rearrangements are described. Here, we bring a new light to the involvement of mitochondrial replication in the strand asymmetry of the vertebrate mtDNA. Using several species of deep-sea hatchetfish (Sternoptychidae) displaying distinct mtDNA structural arrangements, we unravel the inversion of the coding direction of protein-coding genes (PCGs). This unexpected change is coupled with a strand asymmetry nucleotide composition reversal and is shown to be directly related to the strand location of the Control Region (CR). An analysis of the fourfold redundant sites of the PCGs (greater than 6000 vertebrates), revealed the rarity of this phenomenon, found in nine fish species (five deep-sea hatchetfish). Curiously, in Antarctic notothenioid fishes (Trematominae), where a single PCG inversion (the only other record in fish) is coupled with the inversion of the CR, the standard asymmetry is disrupted for the remaining PCGs but not yet reversed, suggesting a transitory state. Our results hint that a relaxation of the classic vertebrate mitochondrial structural stasis promotes disruption of the natural balance of asymmetry of the mtDNA. These findings support the long-lasting hypothesis that replication is the main molecular mechanism promoting the strand-specific compositional bias of this unique and indispensable molecule.

Keywords:  deep-sea fish; mitochondrial gene order; mitogenome; rearrangements; strand asymmetry

DOI:  https://doi.org/10.1098/rsob.230181