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BioRxiv : the Preprint Server For... Mar 2024Dynamins, or dynamin-related proteins (DRPs), are large mechano-sensitive GTPases mediating membrane dynamics or organellar fission/fusion events. encodes three...
UNLABELLED
Dynamins, or dynamin-related proteins (DRPs), are large mechano-sensitive GTPases mediating membrane dynamics or organellar fission/fusion events. encodes three dynamin-like proteins whose functions are poorly understood. Here, we demonstrate that PfDyn2 mediates both apicoplast and mitochondrial fission. Using super-resolution and ultrastructure expansion microscopy, we show that PfDyn2 is expressed in the schizont stage and localizes to both the apicoplast and mitochondria. Super-resolution long-term live cell microscopy shows that PfDyn2-deficient parasites cannot complete cytokinesis because the apicoplast and mitochondria do not undergo fission. Further, the basal complex or cytokinetic ring in cannot fully contract upon PfDyn2 depletion, a phenotype secondary to physical blockage of undivided organelles in the middle of the ring. Our data suggest that organellar fission defects result in aberrant schizogony, generating unsuccessful merozoites. The unique biology of PfDyn2, mediating both apicoplast and mitochondrial fission, has not been observed in other organisms possessing two endosymbiotic organelles.
HIGHLIGHTS
PfDyn2 is essential for schizont-stage development.PfDyn2 mediates both apicoplast and mitochondrial fission.Deficiency of PfDyn2 leads to organellar fission failures and blockage of basal complex contraction.Addition of apicoplast-derived metabolite IPP does not rescue the growth defects.
PubMed: 38559241
DOI: 10.1101/2024.03.15.585229 -
Free Radical Biology & Medicine Jun 2024Acute respiratory distress syndrome (ARDS) is an acute and severe clinical complication lacking effective therapeutic interventions. The disruption of the lung...
Acute respiratory distress syndrome (ARDS) is an acute and severe clinical complication lacking effective therapeutic interventions. The disruption of the lung epithelial barrier plays a crucial role in ARDS pathogenesis. Recent studies have proposed the involvement of abnormal mitochondrial dynamics mediated by dynamin-related protein 1 (Drp1) in the mechanism of impaired epithelial barrier in ARDS. Hydrogen is an anti-oxidative stress molecule that regulates mitochondrial function via multiple signaling pathways. Our previous study confirmed that hydrogen modulated oxidative stress and attenuated acute pulmonary edema in ARDS by upregulating thioredoxin 1 (Trx1) expression, but the exact mechanism remains unclear. This study aimed to investigate the effects of hydrogen on mitochondrial dynamics both in vivo and in vitro. Our study revealed that hydrogen inhibited lipopolysaccharide (LPS)-induced phosphorylation of Drp1 (at Ser616), suppressed Drp1-mediated mitochondrial fission, alleviated epithelial tight junction damage and cell apoptosis, and improved the integrity of the epithelial barrier. This process was associated with the upregulation of Trx1 in lung epithelial tissues of ARDS mice by hydrogen. In addition, hydrogen treatment reduced the production of reactive oxygen species in LPS-induced airway epithelial cells (AECs) and increased the mitochondrial membrane potential, indicating that the mitochondrial dysfunction was restored. Then, the expression of tight junction proteins occludin and zonula occludens 1 was upregulated, and apoptosis in AECs was alleviated. Remarkably, the protective effects of hydrogen on the mitochondrial and epithelial barrier were eliminated after applying the Trx1 inhibitor PX-12. The results showed that hydrogen significantly inhibited the cell apoptosis and the disruption of epithelial tight junctions, maintaining the integrity of the epithelial barrier in mice of ARDS. This might be related to the inhibition of Drp1-mediated mitochondrial fission through the Trx1 pathway. The findings of this study provided a new theoretical basis for the application of hydrogen in the clinical treatment of ARDS.
Topics: Animals; Thioredoxins; Mitochondrial Dynamics; Dynamins; Respiratory Distress Syndrome; Mice; Humans; Hydrogen; Lipopolysaccharides; Lung; Signal Transduction; Reactive Oxygen Species; Male; Apoptosis; Oxidative Stress; Epithelial Cells; Mitochondria; Disease Models, Animal; Tight Junctions; Mice, Inbred C57BL; Phosphorylation
PubMed: 38554812
DOI: 10.1016/j.freeradbiomed.2024.03.022 -
The Journal of Endocrinology Jun 2024Diabetic nephropathy (DN) is one of the most frequent complications of diabetes. Early stages of DN are associated with hyperinsulinemia and progressive insulin...
Diabetic nephropathy (DN) is one of the most frequent complications of diabetes. Early stages of DN are associated with hyperinsulinemia and progressive insulin resistance in insulin-sensitive cells, including podocytes. The diabetic environment induces pathological changes, especially in podocyte bioenergetics, which is tightly linked with mitochondrial dynamics. The regulatory role of insulin in mitochondrial morphology in podocytes has not been fully elucidated. Therefore, the main goal of the present study was to investigate effects of insulin on the regulation of mitochondrial dynamics and bioenergetics in human podocytes. Biochemical analyses were performed to assess oxidative phosphorylation efficiency by measuring the oxygen consumption rate (OCR) and glycolysis by measuring the extracellular acidification rate (ECAR). mRNA and protein expression were determined by real-time polymerase chain reaction and Western blot. The intracellular mitochondrial network was visualized by MitoTracker staining. All calculations were conducted using CellProfiler software. Short-term insulin exposure exerted inhibitory effects on various parameters of oxidative respiration and adenosine triphosphate production, and glycolysis flux was elevated. After a longer time of treating cells with insulin, an increase in mitochondrial size was observed, accompanied by a reduction of expression of the mitochondrial fission markers DRP1 and FIS1 and an increase in mitophagy. Overall, we identified a previously unknown role for insulin in the regulation of oxidative respiration and glycolysis and elucidated mitochondrial dynamics in human podocytes. The present results emphasize the importance of the duration of insulin stimulation for its metabolic and molecular effects, which should be considered in clinical and experimental studies of DN.
Topics: Podocytes; Humans; Mitochondrial Dynamics; Insulin; Energy Metabolism; Glycolysis; Mitochondria; Oxygen Consumption; Diabetic Nephropathies; Dynamins; Membrane Proteins; Mitochondrial Proteins; Oxidative Phosphorylation; GTP Phosphohydrolases; Mitophagy; Cell Line
PubMed: 38552310
DOI: 10.1530/JOE-23-0357 -
International Immunopharmacology May 2024Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is one of the most prevalent forms of autoimmune encephalitis, characterized by a series of neurological and...
Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is one of the most prevalent forms of autoimmune encephalitis, characterized by a series of neurological and psychiatric symptoms, including cognitive impairment, seizures and psychosis. The underlying mechanism of anti-NMDAR encephalitis remains unclear. In the current study, the mouse model of anti-NMDAR encephalitis with active immunization was performed. We first uncovered excessive mitochondrial fission in the hippocampus and temporal cortex of anti-NMDAR encephalitis mice, indicated by elevated level of Phospho-DRP1 (Ser616) (p-Drp1-S616). Moreover, blockade of the autophagic flux was also demonstrated, leading to the accumulation of fragmented mitochondria, and elevated levels of mitochondrial reactive oxygen species (mtROS) and mitochondrial DNA (mtDNA) in anti-NMDAR encephalitis. More importantly, we found that the mTOR signaling pathway was overactivated, which could aggravate mitochondrial fission and inhibit autophagy, resulting in mitochondrial dysfunction. While rapamycin, the specific inhibitor of the mTOR signaling pathway, significantly alleviated mitochondrial dysfunction by inhibiting mitochondrial fission and enhancing autophagy. Levels of mtROS and mtDNA were markedly reduced after the treatment of rapamycin. In addition, rapamycin also significantly alleviated cognitive dysfunction and anxious behaviors found in anti-NMDAR encephalitis mice. Thus, our study reveals the vital role of mitochondrial dysfunction in pathological mechanism of anti-NMDAR encephalitis and lays a theoretical foundation for rapamycin to become a clinically targeted drug for anti-NMDAR encephalitis.
Topics: Animals; Anti-N-Methyl-D-Aspartate Receptor Encephalitis; Mitochondria; Sirolimus; Mice; Disease Models, Animal; TOR Serine-Threonine Kinases; Reactive Oxygen Species; Mitochondrial Dynamics; DNA, Mitochondrial; Autophagy; Signal Transduction; Female; Dynamins; Hippocampus; Cognitive Dysfunction; Humans; Mice, Inbred C57BL
PubMed: 38552295
DOI: 10.1016/j.intimp.2024.111910 -
Proceedings of the National Academy of... Apr 2024Mitochondria constantly fuse and divide for mitochondrial inheritance and functions. Here, we identified a distinct type of naturally occurring fission, tail-autotomy...
Mitochondria constantly fuse and divide for mitochondrial inheritance and functions. Here, we identified a distinct type of naturally occurring fission, tail-autotomy fission, wherein a tail-like thin tubule protrudes from the mitochondrial body and disconnects, resembling autotomy. Next, utilizing an optogenetic mitochondria-specific mechanostimulator, we revealed that mechanical tensile force drives tail-autotomy fission. This force-induced fission involves DRP1/MFF and endoplasmic reticulum tubule wrapping. It redistributes mitochondrial DNA, producing mitochondrial fragments with or without mitochondrial DNA for different fates. Moreover, tensile force can decouple outer and inner mitochondrial membranes, pulling out matrix-excluded tubule segments. Subsequent tail-autotomy fission separates the matrix-excluded tubule segments into matrix-excluded mitochondrial-derived vesicles (MDVs) which recruit Parkin and LC3B, indicating the unique role of tail-autotomy fission in segregating only outer membrane components for mitophagy. Sustained force promotes fission and MDV biogenesis more effectively than transient one. Our results uncover a mechanistically and functionally distinct type of fission and unveil the role of tensile forces in modulating fission and MDV biogenesis for quality control, underscoring the heterogeneity of fission and mechanoregulation of mitochondrial dynamics.
Topics: Mitochondrial Dynamics; Membrane Proteins; Mitochondrial Proteins; Mitochondria; DNA, Mitochondrial; Quality Control; Dynamins
PubMed: 38547062
DOI: 10.1073/pnas.2217019121 -
Behavior Genetics May 2024Head grooming in Drosophila consists of repeated sweeps of the legs across the head, comprising regular cycles. We used the GAL4-UAS system to study the effects of...
Head grooming in Drosophila consists of repeated sweeps of the legs across the head, comprising regular cycles. We used the GAL4-UAS system to study the effects of overexpressing shibire and of Adar knockdown via RNA interference, on the period of head-grooming cycles in Drosophila. Overexpressing shibire interferes with synaptic vesicle recycling and thus with cell communication, while Adar knockdown reduces RNA editing of neuronal transcripts for a large number of genes. All transgenic flies and their controls were tested at 22° to avoid temperature effects; in wild type, cycle frequency varied with temperature with a Q of 1.3. Two experiments were performed with transgenic shibire: (1) each fly was heat-shocked for 10 min at 30° immediately before testing at 22° and (2) flies were not heat shocked. In both experiments, cycle period was increased when shibire was overexpressed in all neurons, but was not increased when shibire was overexpressed in motoneurons alone. We hypothesize that grooming cycles in flies overexpressing shibire are lengthened because of synaptic impairment in neural circuits that control head-grooming cycles. In flies with constitutive, pan-neuronal Adar knockdown, cycle period was more variable within individuals, but mean cycle period was not significantly altered. We conclude that RNA editing is essential for the maintenance of within-individual stereotypy of head-grooming cycles.
Topics: Humans; Animals; Drosophila; Drosophila Proteins; Dynamins; Grooming; Neurons; Drosophila melanogaster
PubMed: 38536593
DOI: 10.1007/s10519-024-10180-3 -
Journal of Translational Medicine Mar 2024The treatment of spinal cord injury (SCI) has always been a significant research focus of clinical neuroscience, with inhibition of microglia-mediated neuro-inflammation...
Caffeic acid phenethyl ester inhibits neuro-inflammation and oxidative stress following spinal cord injury by mitigating mitochondrial dysfunction via the SIRT1/PGC1α/DRP1 signaling pathway.
BACKGROUND
The treatment of spinal cord injury (SCI) has always been a significant research focus of clinical neuroscience, with inhibition of microglia-mediated neuro-inflammation as well as oxidative stress key to successful SCI patient treatment. Caffeic acid phenethyl ester (CAPE), a compound extracted from propolis, has both anti-inflammatory and anti-oxidative effects, but its SCI therapeutic effects have rarely been reported.
METHODS
We constructed a mouse spinal cord contusion model and administered CAPE intraperitoneally for 7 consecutive days after injury, and methylprednisolone (MP) was used as a positive control. Hematoxylin-eosin, Nissl, and Luxol Fast Blue staining were used to assess the effect of CAPE on the structures of nervous tissue after SCI. Basso Mouse Scale scores and footprint analysis were used to explore the effect of CAPE on the recovery of motor function by SCI mice. Western blot analysis and immunofluorescence staining assessed levels of inflammatory mediators and oxidative stress-related proteins both in vivo and in vitro after CAPE treatment. Further, reactive oxygen species (ROS) within the cytoplasm were detected using an ROS kit. Changes in mitochondrial membrane potential after CAPE treatment were detected with 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide. Mechanistically, western blot analysis and immunofluorescence staining were used to examine the effect of CAPE on the SIRT1/PGC1α/DRP1 signaling pathway.
RESULTS
CAPE-treated SCI mice showed less neuronal tissue loss, more neuronal survival, and reduced demyelination. Interestingly, SCI mice treated with CAPE showed better recovery of motor function. CAPE treatment reduced the expression of inflammatory and oxidative mediators, including iNOS, COX-2, TNF-α, IL-1β, 1L-6, NOX-2, and NOX-4, as well as the positive control MP both in vitro and in vivo. In addition, molecular docking experiments showed that CAPE had a high affinity for SIRT1, and that CAPE treatment significantly activated SIRT1 and PGC1α, with down-regulation of DRP1. Further, CAPE treatment significantly reduced the level of ROS in cellular cytoplasm and increased the mitochondrial membrane potential, which improved normal mitochondrial function. After administering the SIRT1 inhibitor nicotinamide, the effect of CAPE on neuro-inflammation and oxidative stress was reversed.On the contrary, SIRT1 agonist SRT2183 further enhanced the anti-inflammatory and antioxidant effects of CAPE, indicating that the anti-inflammatory and anti-oxidative stress effects of CAPE after SCI were dependent on SIRT1.
CONCLUSION
CAPE inhibits microglia-mediated neuro-inflammation and oxidative stress and supports mitochondrial function by regulating the SIRT1/PGC1α/DRP1 signaling pathway after SCI. These effects demonstrate that CAPE reduces nerve tissue damage. Therefore, CAPE is a potential drug for the treatment of SCI through production of anti-inflammatory and anti-oxidative stress effects.
Topics: Animals; Mice; Anti-Inflammatory Agents; Caffeic Acids; Inflammation; Methylprednisolone; Mitochondrial Diseases; Molecular Docking Simulation; Oxidative Stress; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; Phenylethyl Alcohol; Reactive Oxygen Species; Signal Transduction; Sirtuin 1; Spinal Cord; Spinal Cord Injuries; Dynamins
PubMed: 38528569
DOI: 10.1186/s12967-024-05089-8 -
Shock (Augusta, Ga.) Jul 2024Proinflammatory hyperactivation of Kupffer cells (KCs) is foremost involved in the pathogenesis of sepsis-induced liver injury. Our previous study found that stimulator...
Proinflammatory hyperactivation of Kupffer cells (KCs) is foremost involved in the pathogenesis of sepsis-induced liver injury. Our previous study found that stimulator of interferon genes (STING) signaling was activated in KCs in response of lipopolysaccharide (LPS) and knocking down dynamin-related protein 1 (DRP1) in KCs effectively inhibited the activation of STING signaling and the subsequent production of proinflammatory cytokines. In this study, we demonstrated that in vivo treatment with mitochondrial division inhibitor 1 (Mdivi-1), a selective inhibitor of DRP1, alleviated cecal ligation and puncture (CLP)-induced liver injury with the improvement of liver pathology and function. Moreover, we found that STING in liver was mainly concentrated in KCs and STING signaling was significantly activated in KCs after CLP. The STING deficiency effectively ameliorated liver injury and decreased the mortality of septic mice, which were reversely worsened by the enhanced activation of STING with DMXAA. The further study showed that Mdivi-1 markedly attenuated STING signaling activation in KCs and inhibited systemic inflammatory response. Importantly, DMXAA application in CLP mice blunted Mdivi-1's liver protection effect. Taken together, our study confirmed Mdivi-1 effectively alleviated CLP-induced liver injury partially through inhibiting STING signaling activation in KCs, which provides new insights and a novel potential pharmacological therapeutic target for treating septic liver injury.
Topics: Animals; Sepsis; Mice; Membrane Proteins; Signal Transduction; Kupffer Cells; Male; Mice, Inbred C57BL; Quinazolinones; Liver; Dynamins
PubMed: 38526162
DOI: 10.1097/SHK.0000000000002349 -
Nature Communications Mar 2024Homotypic membrane fusion of the endoplasmic reticulum (ER) is mediated by dynamin-like GTPase atlastin (ATL). This fundamental process relies on GTP-dependent domain...
Homotypic membrane fusion of the endoplasmic reticulum (ER) is mediated by dynamin-like GTPase atlastin (ATL). This fundamental process relies on GTP-dependent domain rearrangements in the N-terminal region of ATL (ATL), including the GTPase domain and three-helix bundle (3HB). However, its conformational dynamics during the GTPase cycle remain elusive. Here, we combine single-molecule FRET imaging and molecular dynamics simulations to address this conundrum. Different from the prevailing model, ATL can form a loose crossover dimer upon GTP binding, which is tightened by GTP hydrolysis for membrane fusion. Furthermore, the α-helical motif between the 3HB and transmembrane domain, which is embedded in the surface of the lipid bilayer and self-associates in the crossover dimer, is required for ATL function. To recycle the proteins, Pi release, which disassembles the dimer, activates frequent relative movements between the GTPase domain and 3HB, and subsequent GDP dissociation alters the conformational preference of the ATL monomer for entering the next reaction cycle. Finally, we found that two disease-causing mutations affect human ATL1 activity by destabilizing GTP binding-induced loose crossover dimer formation and the membrane-embedded helix, respectively. These results provide insights into ATL-mediated homotypic membrane fusion and the pathological mechanisms of related disease.
Topics: Humans; Drosophila Proteins; Membrane Fusion; GTP Phosphohydrolases; Hydrolysis; Guanosine Triphosphate
PubMed: 38509071
DOI: 10.1038/s41467-024-46919-z -
Journal of Cell Science Apr 2024Clathrin-mediated endocytosis (CME) is vital for the regulation of plant growth and development through controlling plasma membrane protein composition and cargo uptake....
Clathrin-mediated endocytosis (CME) is vital for the regulation of plant growth and development through controlling plasma membrane protein composition and cargo uptake. CME relies on the precise recruitment of regulators for vesicle maturation and release. Homologues of components of mammalian vesicle scission are strong candidates to be part of the scission machinery in plants, but the precise roles of these proteins in this process are not fully understood. Here, we characterised the roles of the plant dynamin-related protein 2 (DRP2) family (hereafter DRP2s) and SH3-domain containing protein 2 (SH3P2), the plant homologue to recruiters of dynamins, such as endophilin and amphiphysin, in CME by combining high-resolution imaging of endocytic events in vivo and characterisation of the purified proteins in vitro. Although DRP2s and SH3P2 arrive similarly late during CME and physically interact, genetic analysis of the sh3p123 triple mutant and complementation assays with non-SH3P2-interacting DRP2 variants suggest that SH3P2 does not directly recruit DRP2s to the site of endocytosis. These observations imply that, despite the presence of many well-conserved endocytic components, plants have acquired a distinct mechanism for CME.
Topics: Arabidopsis; Arabidopsis Proteins; Clathrin; Dynamins; Endocytosis; GTP-Binding Proteins; Mutation
PubMed: 38506228
DOI: 10.1242/jcs.261720