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Nature Communications Jan 2024Membrane fusion and budding mediate fundamental processes like intracellular trafficking, exocytosis, and endocytosis. Fusion is thought to open a nanometer-range pore... (Review)
Review
Membrane fusion and budding mediate fundamental processes like intracellular trafficking, exocytosis, and endocytosis. Fusion is thought to open a nanometer-range pore that may subsequently close or dilate irreversibly, whereas budding transforms flat membranes into vesicles. Reviewing recent breakthroughs in real-time visualization of membrane transformations well exceeding this classical view, we synthesize a new model and describe its underlying mechanistic principles and functions. Fusion involves hemi-to-full fusion, pore expansion, constriction and/or closure while fusing vesicles may shrink, enlarge, or receive another vesicle fusion; endocytosis follows exocytosis primarily by closing Ω-shaped profiles pre-formed through the flat-to-Λ-to-Ω-shape transition or formed via fusion. Calcium/SNARE-dependent fusion machinery, cytoskeleton-dependent membrane tension, osmotic pressure, calcium/dynamin-dependent fission machinery, and actin/dynamin-dependent force machinery work together to generate fusion and budding modes differing in pore status, vesicle size, speed and quantity, controls release probability, synchronization and content release rates/amounts, and underlies exo-endocytosis coupling to maintain membrane homeostasis. These transformations, underlying mechanisms, and functions may be conserved for fusion and budding in general.
Topics: Cell Membrane; Calcium; Membrane Fusion; Exocytosis; Dynamins; Secretory Vesicles
PubMed: 38167896
DOI: 10.1038/s41467-023-44539-7 -
Journal of Neuroinflammation Jan 2020Out of the myriad of complications associated with septic shock, septic-associated encephalopathy (SAE) carries a significant risk of morbidity and mortality....
BACKGROUND
Out of the myriad of complications associated with septic shock, septic-associated encephalopathy (SAE) carries a significant risk of morbidity and mortality. Blood-brain-barrier (BBB) impairment, which subsequently leads to increased vascular permeability, has been associated with neuronal injury in sepsis. Thus, preventing BBB damage is an attractive therapeutic target. Mitochondrial dysfunction is an important contributor of sepsis-induced multi-organ system failure. More recently, mitochondrial dysfunction in endothelial cells has been implicated in mediating BBB failure in stroke, multiple sclerosis and in other neuroinflammatory disorders. Here, we focused on Drp1-mediated mitochondrial dysfunction in endothelial cells as a potential target to prevent BBB failure in sepsis.
METHODS
We used lipopolysaccharide (LPS) to induce inflammation and BBB disruption in a cell culture as well as in murine model of sepsis. BBB disruption was assessed by measuring levels of key tight-junction proteins. Brain cytokines levels, oxidative stress markers, and activity of mitochondrial complexes were measured using biochemical assays. Astrocyte and microglial activation were measured using immunoblotting and qPCR. Transwell cultures of brain microvascular endothelial cells co-cultured with astrocytes were used to assess the effect of LPS on expression of tight-junction proteins, mitochondrial function, and permeability to fluorescein isothiocyanate (FITC) dextran. Finally, primary neuronal cultures exposed to LPS were assessed for mitochondrial dysfunction.
RESULTS
LPS induced a strong brain inflammatory response and oxidative stress in mice which was associated with increased Drp1 activation and mitochondrial localization. Particularly, Drp1-(Fission 1) Fis1-mediated oxidative stress also led to an increase in expression of vascular permeability regulators in the septic mice. Similarly, mitochondrial defects mediated via Drp1-Fis1 interaction in primary microvascular endothelial cells were associated with increased BBB permeability and loss of tight-junctions after acute LPS injury. P110, an inhibitor of Drp1-Fis1 interaction, abrogated these defects, thus indicating a critical role for this interaction in mediating sepsis-induced brain dysfunction. Finally, LPS mediated a direct toxic effect on primary cortical neurons, which was abolished by P110 treatment.
CONCLUSIONS
LPS-induced impairment of BBB appears to be dependent on Drp1-Fis1-mediated mitochondrial dysfunction. Inhibition of mitochondrial dysfunction with P110 may have potential therapeutic significance in septic encephalopathy.
Topics: Animals; Blood-Brain Barrier; Brain Diseases; Cells, Cultured; Cytokines; Dynamins; Endothelial Cells; Lipopolysaccharides; Macrophage Activation; Mice; Mice, Inbred BALB C; Mitochondrial Diseases; Neuroglia; Oxidative Stress; Primary Cell Culture; Sepsis; Tight Junction Proteins
PubMed: 31987040
DOI: 10.1186/s12974-019-1689-8 -
Circulation Research Jun 2023
Topics: Humans; Mitophagy; Cardiomyopathies; Heart; Dynamins; Mitochondrial Dynamics
PubMed: 37347834
DOI: 10.1161/CIRCRESAHA.123.323013 -
Neuron Sep 2022Dynamin mediates fission of vesicles from the plasma membrane during endocytosis. Typically, dynamin is recruited from the cytosol to endocytic sites, requiring seconds...
Dynamin mediates fission of vesicles from the plasma membrane during endocytosis. Typically, dynamin is recruited from the cytosol to endocytic sites, requiring seconds to tens of seconds. However, ultrafast endocytosis in neurons internalizes vesicles as quickly as 50 ms during synaptic vesicle recycling. Here, we demonstrate that Dynamin 1 is pre-recruited to endocytic sites for ultrafast endocytosis. Specifically, Dynamin 1xA, a splice variant of Dynamin 1, interacts with Syndapin 1 to form molecular condensates on the plasma membrane. Single-particle tracking of Dynamin 1xA molecules confirms the liquid-like property of condensates in vivo. When Dynamin 1xA is mutated to disrupt its interaction with Syndapin 1, the condensates do not form, and consequently, ultrafast endocytosis slows down by 100-fold. Mechanistically, Syndapin 1 acts as an adaptor by binding the plasma membrane and stores Dynamin 1xA at endocytic sites. This cache bypasses the recruitment step and accelerates endocytosis at synapses.
Topics: Dynamin I; Dynamins; Endocytosis; Nerve Tissue Proteins; Synaptic Vesicles
PubMed: 35809574
DOI: 10.1016/j.neuron.2022.06.010 -
Cell Death & Disease Sep 2023There is an urgent need for novel diagnostic and therapeutic strategies for patients with Glioblastoma multiforme (GBM). Previous studies have shown that BCL2 like 13...
There is an urgent need for novel diagnostic and therapeutic strategies for patients with Glioblastoma multiforme (GBM). Previous studies have shown that BCL2 like 13 (BCL2L13) is a member of the BCL2 family regulating cell growth and apoptosis in different types of tumors. However, the clinical significance, biological role, and potential mechanism in GBM remain unexplored. In this study, we showed that BCL2L13 expression is significantly upregulated in GBM cell lines and clinical GBM tissue samples. Mechanistically, BCL2L13 targeted DNM1L at the Ser616 site, leading to mitochondrial fission and high mitophagy flux. Functionally, these alterations significantly promoted the proliferation and invasion of GBM cells both in vitro and in vivo. Overall, our findings demonstrated that BCL2L13 plays a significant role in promoting mitophagy via DNM1L-mediated mitochondrial fission in GBM. Therefore, the regulation and biological function of BCL2L13 render it a candidate molecular target for treating GBM.
Topics: Humans; Glioblastoma; Mitochondrial Dynamics; Mitophagy; Apoptosis; Proto-Oncogene Proteins c-bcl-2; Dynamins
PubMed: 37660127
DOI: 10.1038/s41419-023-06112-4 -
Cells Aug 2022Endocytosis is a fundamental mechanism by which cells perform housekeeping functions. It occurs via a variety of mechanisms and involves many regulatory proteins. The... (Review)
Review
Endocytosis is a fundamental mechanism by which cells perform housekeeping functions. It occurs via a variety of mechanisms and involves many regulatory proteins. The GTPase dynamin acts as a "molecular scissor" to form endocytic vesicles and is a critical regulator among the proteins involved in endocytosis. Some GTPases (e.g., Cdc42, arf6, RhoA), membrane proteins (e.g., flotillins, tetraspanins), and secondary messengers (e.g., calcium) mediate dynamin-independent endocytosis. These pathways may be convergent, as multiple pathways exist in a single cell. However, what determines the specific path of endocytosis is complex and challenging to comprehend. This review summarizes the mechanisms of dynamin-independent endocytosis, the involvement of microRNAs, and factors that contribute to the cellular decision about the specific route of endocytosis.
Topics: Dynamins; Endocytosis; Transport Vesicles
PubMed: 36010634
DOI: 10.3390/cells11162557 -
Redox Biology Apr 2024Heart failure with preserved ejection fraction (HFpEF) is a devastating health issue although limited knowledge is available for its pathogenesis and therapeutics. Given...
AIMS
Heart failure with preserved ejection fraction (HFpEF) is a devastating health issue although limited knowledge is available for its pathogenesis and therapeutics. Given the perceived involvement of mitochondrial dysfunction in HFpEF, this study was designed to examine the role of mitochondrial dynamics in the etiology of HFpEF.
METHOD AND RESULTS
Adult mice were placed on a high fat diet plus l-NAME in drinking water ('two-hit' challenge to mimic obesity and hypertension) for 15 consecutive weeks. Mass spectrometry revealed pronounced changes in mitochondrial fission protein Drp1 and E3 ligase FBXL4 in 'two-hit' mouse hearts. Transfection of FBXL4 rescued against HFpEF-compromised diastolic function, cardiac geometry, and mitochondrial integrity without affecting systolic performance, in conjunction with altered mitochondrial dynamics and integrity (hyperactivation of Drp1 and unchecked fission). Mass spectrometry and co-IP analyses unveiled an interaction between FBXL4 and Drp1 to foster ubiquitination and degradation of Drp1. Truncated mutants of FBXL4 (Delta-Fbox) disengaged interaction between FBXL4 and Drp1. Metabolomic and proteomics findings identified deranged fatty acid and glucose metabolism in HFpEF patients and mice. A cellular model was established with concurrent exposure of high glucose and palmitic acid as a 'double-damage' insult to mimic diastolic anomalies in HFpEF. Transfection of FBXL4 mitigated 'double-damage'-induced cardiomyocyte diastolic dysfunction and mitochondrial injury, the effects were abolished and mimicked by Drp1 knock-in and knock-out, respectively. HFpEF downregulated sarco(endo)plasmic reticulum (SR) Ca uptake protein SERCA2a while upregulating phospholamban, RYR1, IP3R1, IP3R3 and Na-Ca exchanger with unaltered SR Ca load. FBXL4 ablated 'two-hit' or 'double-damage'-induced changes in SERCA2a, phospholamban and mitochondrial injury.
CONCLUSION
FBXL4 rescued against HFpEF-induced cardiac remodeling, diastolic dysfunction, and mitochondrial injury through reverting hyperactivation of Drp1-mediated mitochondrial fission, underscoring the therapeutic promises of FBXL4 in HFpEF.
Topics: Humans; Mice; Animals; Heart Failure; Mitochondrial Dynamics; Stroke Volume; Myocytes, Cardiac; Cardiomyopathies; Dynamins
PubMed: 38359748
DOI: 10.1016/j.redox.2024.103081 -
Nature Communications Jul 2023The large cytosolic GTPase, dynamin-related protein 1 (Drp1), mediates both physiological and pathological mitochondrial fission. Cell stress triggers Drp1 binding to...
The large cytosolic GTPase, dynamin-related protein 1 (Drp1), mediates both physiological and pathological mitochondrial fission. Cell stress triggers Drp1 binding to mitochondrial Fis1 and subsequently, mitochondrial fragmentation, ROS production, metabolic collapse, and cell death. Because Drp1 also mediates physiological fission by binding to mitochondrial Mff, therapeutics that inhibit pathological fission should spare physiological mitochondrial fission. P110, a peptide inhibitor of Drp1-Fis1 interaction, reduces pathology in numerous models of neurodegeneration, ischemia, and sepsis without blocking the physiological functions of Drp1. Since peptides have pharmacokinetic limitations, we set out to identify small molecules that mimic P110's benefit. We map the P110-binding site to a switch I-adjacent grove (SWAG) on Drp1. Screening for SWAG-binding small molecules identifies SC9, which mimics P110's benefits in cells and a mouse model of endotoxemia. We suggest that the SWAG-binding small molecules discovered in this study may reduce the burden of Drp1-mediated pathologies and potentially pathologies associated with other members of the GTPase family.
Topics: Animals; Mice; Allosteric Site; Disease Models, Animal; Dynamins; GTP Phosphohydrolases; Mitochondria; Mitochondrial Dynamics; Mitochondrial Proteins
PubMed: 37468472
DOI: 10.1038/s41467-023-40043-0 -
Oxidative Medicine and Cellular... 2022Stroke is one of the leading causes of death and disability in the world. However, the pathophysiological process of stroke is still not fully clarified. Mitochondria... (Review)
Review
Stroke is one of the leading causes of death and disability in the world. However, the pathophysiological process of stroke is still not fully clarified. Mitochondria play an important role in promoting nerve survival and are an important drug target for the treatment of stroke. Mitochondrial dysfunction is one of the hallmarks of stroke. Mitochondria are in a state of continuous fission and fusion, which are termed as mitochondrial dynamics. Mitochondrial dynamics are very important for maintaining various functions of mitochondria. In this review, we will introduce the structure and functions of mitochondrial fission and fusion related proteins and discuss their role in the pathophysiologic process of stroke. A better understanding of mitochondrial dynamin in stroke will pave way for the development of new therapeutic options.
Topics: Drug Delivery Systems; Dynamins; Humans; Mitochondria; Mitochondrial Dynamics; Mitochondrial Proteins; Stroke
PubMed: 35571256
DOI: 10.1155/2022/2504798 -
Redox Biology Dec 2022Hydrogen sulfide (HS), produced by cystathionine γ lyase (CSE), is an important endogenous gasotransmitter to maintain heart function. However, the molecular mechanism...
Hydrogen sulfide (HS), produced by cystathionine γ lyase (CSE), is an important endogenous gasotransmitter to maintain heart function. However, the molecular mechanism for how HS influences the mitochondrial morphology during heart failure remains poorly understood. Here, we found that CSE/HS pathway mediated cardiac function and mitochondrial morphology through regulating dynamin related protein 1 (Drp1) activity and translocation. Mechanistically, elevation of HS levels by CSE overexpression declined protein level, phosphorylation (Ser 616), oligomerization and GTPase activity of Drp1 by S-sulfhydration in mouse hearts. Interestingly, Drp1 S-sulfhydration directly competed with S-nitrosylation by nitric oxide at the specific cysteine 607. The non-S-sulfhydration of Drp1 mutation (C607A) attenuated the regulatory effect of HS on Drp1 activation, mitochondrial fission and heart function. Moreover, the non-canonical role of Drp1 mediated isoprenaline-induced mitochondrial dysfunction and cardiomyocyte death through interaction with voltage-dependent anion channel 1. These results uncover that a novel mechanism that HS S-sulfhydrated Drp1 at cysteine 607 to prevent heart failure through modulating its activity and mitochondrial translocation. Our findings also provide initial evidence demonstrating that Drp1 may be a critical regulator as well as an effective strategy for heart dysfunction.
Topics: Mice; Animals; Cystathionine gamma-Lyase; Cysteine; Hydrogen Sulfide; Dynamins; Heart Failure
PubMed: 36327794
DOI: 10.1016/j.redox.2022.102519