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Current Opinion in Neurobiology Oct 1995Temperature-sensitive shibire mutants of Drosophila melanogaster become rapidly paralyzed upon a shift to the restrictive temperature, which is due to a block in... (Review)
Review
Temperature-sensitive shibire mutants of Drosophila melanogaster become rapidly paralyzed upon a shift to the restrictive temperature, which is due to a block in synaptic vesicle endocytosis. The shibire gene encodes the GTPase dynamin. Recent studies have shown that dynamin forms rings at the neck of invaginated clathrin-coated pits, and have suggested that a conformational change in the ring, which correlates with GTP hydrolysis, plays an essential role in vesicle fission.
Topics: Animals; Drosophila Proteins; Dynamins; Endocytosis; GTP Phosphohydrolases; Models, Molecular; Presynaptic Terminals
PubMed: 8580706
DOI: 10.1016/0959-4388(95)80059-x -
Cells Jul 2023Mitochondria, which generate ATP through aerobic respiration, also have important noncanonical functions. Mitochondria are dynamic organelles, that engage in fission... (Review)
Review
Mitochondria, which generate ATP through aerobic respiration, also have important noncanonical functions. Mitochondria are dynamic organelles, that engage in fission (division), fusion (joining) and translocation. They also regulate intracellular calcium homeostasis, serve as oxygen-sensors, regulate inflammation, participate in cellular and organellar quality control and regulate the cell cycle. Mitochondrial fission is mediated by the large GTPase, dynamin-related protein 1 (Drp1) which, when activated, translocates to the outer mitochondrial membrane (OMM) where it interacts with binding proteins (Fis1, MFF, MiD49 and MiD51). At a site demarcated by the endoplasmic reticulum, fission proteins create a macromolecular ring that divides the organelle. The functional consequence of fission is contextual. Physiological fission in healthy, nonproliferating cells mediates organellar quality control, eliminating dysfunctional portions of the mitochondria via mitophagy. Pathological fission in somatic cells generates reactive oxygen species and triggers cell death. In dividing cells, Drp1-mediated mitotic fission is critical to cell cycle progression, ensuring that daughter cells receive equitable distribution of mitochondria. Mitochondrial fusion is regulated by the large GTPases mitofusin-1 (Mfn1) and mitofusin-2 (Mfn2), which fuse the OMM, and optic atrophy 1 (OPA-1), which fuses the inner mitochondrial membrane. Mitochondrial fusion mediates complementation, an important mitochondrial quality control mechanism. Fusion also favors oxidative metabolism, intracellular calcium homeostasis and inhibits cell proliferation. Mitochondrial lipids, cardiolipin and phosphatidic acid, also regulate fission and fusion, respectively. Here we review the role of mitochondrial dynamics in health and disease and discuss emerging concepts in the field, such as the role of central versus peripheral fission and the potential role of dynamin 2 (DNM2) as a fission mediator. In hyperproliferative diseases, such as pulmonary arterial hypertension and cancer, Drp1 and its binding partners are upregulated and activated, positing mitochondrial fission as an emerging therapeutic target.
Topics: Humans; Mitochondrial Dynamics; Pulmonary Arterial Hypertension; Calcium; Dynamins; GTP Phosphohydrolases; Cell Cycle; Neoplasms
PubMed: 37508561
DOI: 10.3390/cells12141897 -
The Journal of Biological Chemistry Sep 2004The GTPase dynamin is essential for clathrin-mediated endocytosis. Unlike most GTPases, dynamin has a low affinity for nucleotide, a high rate of GTP hydrolysis, and can...
The GTPase dynamin is essential for clathrin-mediated endocytosis. Unlike most GTPases, dynamin has a low affinity for nucleotide, a high rate of GTP hydrolysis, and can self-assemble, forming higher order structures such as rings and spirals that exhibit up to 100-fold stimulated GTPase activity. The role(s) of GTP binding and/or hydrolysis in endocytosis remain unclear because mutations in the GTPase domain so far studied impair both. We generated a new series of GTPase domain mutants to probe the mechanism of GTP hydrolysis and to further test the role of GTP binding and/or hydrolysis in endocytosis. Each of the mutations had parallel effects on assembly-stimulated and basal GTPase activities. In contrast to previous reports, we find that mutation of Thr-65 to Ala (or Asp or His) dramatically lowered both the rate of assembly-stimulated GTP hydrolysis and the affinity for GTP. The assemblystimulated rate of hydrolysis was lowered by the mutation of Ser-61 to Asp and increased by the mutation of Thr-141 to Ala without significantly altering the Km for GTP. For some mutants and to a lesser extent for WT dynamin, self-assembly dramatically altered the Km for GTP, suggesting that conformational changes in the active site accompany self-assembly. Analysis of transferrin endocytosis rates in cells overexpressing mutant dynamins revealed a stronger correlation with both the basal and assembly-stimulated rates of GTP hydrolysis than with the calculated ratio of dynamin-GTP/free dynamin, suggesting that GTP binding is not sufficient, and GTP hydrolysis is required for clathrin-mediated endocytosis in vivo.
Topics: Adenoviridae; Alanine; Baculoviridae; Binding Sites; Chromatography, Gel; Clathrin; Dynamins; Endocytosis; GTP Phosphohydrolases; Guanosine Triphosphate; Humans; Hydrolysis; Kinetics; Lipids; Models, Chemical; Mutation; Oligonucleotides; Point Mutation; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Serine; Temperature; Threonine; Time Factors; Transferrin
PubMed: 15262989
DOI: 10.1074/jbc.M407007200 -
Journal of Biochemistry Mar 2005Extensive studies on endocytosis in the last decade have resulted in identification of several key molecules that function in clathrin- and dynamin-dependent... (Review)
Review
Extensive studies on endocytosis in the last decade have resulted in identification of several key molecules that function in clathrin- and dynamin-dependent endocytosis. Most endocytic molecules contain multiple binding motifs that mediate protein-protein or protein-lipid interactions, which must be modulated spatially and temporally during endocytosis. Regulation of these interactions is the molecular basis of regulatory mechanisms involved in endocytosis. This review first describes current models of the mechanism of dynamin-dependent fission, then introduces several mechanisms that modulate dynamin GTPase activity and dynamin-dependent vesicle formation. Such mechanisms include regulation by inositol phospholipids, especially phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)], and their metabolism. It concludes by describing the regulation of dynamin 1 by its binding partner, amphiphysin 1, and regulation by cyclin-dependent kinase 5 (Cdk5)-dependent phosphorylation of dynamin 1 and amphiphysin 1. These mechanisms help endocytic molecules to function properly, and cooperatively regulate dynamin-dependent endocytosis.
Topics: Animals; Clathrin-Coated Vesicles; Cyclin-Dependent Kinase 5; Cyclin-Dependent Kinases; Dynamins; Endocytosis; Nerve Tissue Proteins; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositol Phosphates; Phosphorylation
PubMed: 15809324
DOI: 10.1093/jb/mvi052 -
Current Biology : CB Oct 2013Mitochondrial fission is mediated by a dynamin-related GTPase that assembles at constricted sites on the organelle. The mechanism of action of this GTPase in fission is... (Review)
Review
Mitochondrial fission is mediated by a dynamin-related GTPase that assembles at constricted sites on the organelle. The mechanism of action of this GTPase in fission is related to that of classical dynamin, which severs the necks of clathrin-coated pits at the plasma membrane. The scale of these membrane remodeling events differs by an order of magnitude, however, and structural studies have revealed variations in the assembly properties of classical and mitochondrial dynamins that accommodate these differences. Despite this progress, structural and mechanistic models have not yet incorporated a growing number of adaptor proteins that are required for the membrane recruitment and function of mitochondrial dynamins. Here, we review the structure and assembly properties of the yeast and mammalian mitochondrial dynamins and discuss what is known about the activities of their adaptor proteins.
Topics: Adaptor Proteins, Signal Transducing; Animals; Clathrin; Coated Pits, Cell-Membrane; Dynamins; Guanosine Triphosphate; Mitochondria; Mitochondrial Dynamics; Mitochondrial Membranes; Mitochondrial Proteins; Saccharomyces cerevisiae
PubMed: 24112988
DOI: 10.1016/j.cub.2013.08.040 -
Cell Feb 2014Biological membranes undergo constant remodeling by membrane fission and fusion to change their shape and to exchange material between subcellular compartments. During... (Review)
Review
Biological membranes undergo constant remodeling by membrane fission and fusion to change their shape and to exchange material between subcellular compartments. During clathrin-mediated endocytosis, the dynamic assembly and disassembly of protein scaffolds comprising members of the bin-amphiphysin-rvs (BAR) domain protein superfamily constrain the membrane into distinct shapes as the pathway progresses toward fission by the GTPase dynamin. In this Review, we discuss how BAR domain protein assembly and disassembly are controlled in space and time and which structural and biochemical features allow the tight regulation of their shape and function to enable dynamin-mediated membrane fission.
Topics: Animals; Cell Membrane; Clathrin-Coated Vesicles; Dynamins; Endocytosis; Humans; Protein Structure, Tertiary
PubMed: 24581490
DOI: 10.1016/j.cell.2014.02.017 -
Journal of Biochemistry Mar 2020The mitochondrion is an essential organelle for a wide range of cellular processes, including energy production, metabolism, signal transduction and cell death. To... (Review)
Review
The mitochondrion is an essential organelle for a wide range of cellular processes, including energy production, metabolism, signal transduction and cell death. To execute these functions, mitochondria regulate their size, number, morphology and distribution in cells via mitochondrial division and fusion. In addition, mitochondrial division and fusion control the autophagic degradation of dysfunctional mitochondria to maintain a healthy population. Defects in these dynamic membrane processes are linked to many human diseases that include metabolic syndrome, myopathy and neurodegenerative disorders. In the last several years, our fundamental understanding of mitochondrial fusion, division and degradation has been significantly advanced by high resolution structural analyses, protein-lipid biochemistry, super resolution microscopy and in vivo analyses using animal models. Here, we summarize and discuss this exciting recent progress in the mechanism and function of mitochondrial division and fusion.
Topics: Actins; Animals; Dynamins; Endoplasmic Reticulum; GTP Phosphohydrolases; Humans; Lipid Metabolism; Mitochondria; Mitochondrial Dynamics; Mitophagy
PubMed: 31800050
DOI: 10.1093/jb/mvz106 -
American Journal of Physiology. Cell... Jul 2018The constant physiological flux of mitochondrial fission and fusion is inextricably tied to the maintenance of cellular bioenergetics and the fluidity of mitochondrial... (Review)
Review
The constant physiological flux of mitochondrial fission and fusion is inextricably tied to the maintenance of cellular bioenergetics and the fluidity of mitochondrial networks. Yet, the intricacies of this dynamic duo remain unclear in diseases that encompass mitochondrial dysregulation. Particularly, the role of the GTPase fission protein dynamin-related protein 1 (Drp1) is of profound interest. Studies have identified that Drp1 participates in complex signaling pathways, suggesting that the function of mitochondria in pathophysiology may extend far beyond energetics alone. Research indicates that, in stressed conditions, Drp1 translocation to the mitochondria leads to elevated fragmentation and mitophagy; however, despite this, there is limited knowledge about the mechanistic regulation of Drp1 in disease conditions. This review highlights literature about fission, fusion, and, more importantly, discusses Drp1 in cardiac, neural, carcinogenic, renal, and pulmonary diseases. The therapeutic desirability for further research into its contribution to diseases that involve mitochondrial dysregulation is also discussed.
Topics: Animals; Dynamins; GTP Phosphohydrolases; Humans; Mitochondria; Mitochondrial Dynamics; Mitophagy
PubMed: 29669222
DOI: 10.1152/ajpcell.00042.2018 -
Molecular Biology of the Cell Oct 1992We purified a large amount of dynamin with high enzymatical activity from rat brain tissue by a new procedure. Dynamin 0.48 mg was obtained from 20 g of rat brain. The...
We purified a large amount of dynamin with high enzymatical activity from rat brain tissue by a new procedure. Dynamin 0.48 mg was obtained from 20 g of rat brain. The purity of dynamin was almost 98%. Dynamin plays a role of GTPase rather than ATPase. In the absence of microtubules, Michaelis constant (Km) and maximum velocity (Vmax) for dynamin GTPase were 370 microM and 0.25 min-1, respectively, and in their presence, both were significantly accelerated up to 25 microM and 5.5 min-1. On the other hand, the ATPase activity was very low in the absence of microtubules, and even in their presence, Km and Vmax for dynamin ATPase were 0.2 mM and 0.91 min-1. Despite slow GTPase turnover rate in the absence of microtubules, binding of GTP and its nonhydrolizing analogues was very fast, indicating that GTP binding step is not rate limiting. Dynamin did not cause a one-directional consistent microtubule sliding movement just like kinesin or dynein in the presence of 2 mM ATP or 2 mM GTP. We observed the molecular structure of dynamin with low-angle rotary shadowing technique and revealed that the dynamin molecule is globular in shape. Gel filtration assay revealed that these globules were the oligomers of 100-kDa dynamin polypeptide. Dynamin bound to microtubules with a 1:1 approximately 1.2 molar ratio in the absence of GTP. Quick-freeze deep-etch electron microscopy of the dynamin-microtubule complex showed that dynamin decorates the surface of microtubules helically, like a screw bolt, very orderly and tightly with 11.4 +/- 0.9 (SD)nm period. Contrary to the previous report, microtubules make bundles by the attachment of the dynamin helixes around each adjacent microtubule, and no cross-bridge formation was observed.
Topics: Amino Acid Sequence; Animals; Brain Chemistry; Ca(2+) Mg(2+)-ATPase; Dynamins; Freeze Etching; GTP Phosphohydrolases; Guanine Nucleotides; In Vitro Techniques; Kinetics; Microscopy, Electron; Microtubules; Molecular Sequence Data; Molecular Structure; Protein Conformation; Rats
PubMed: 1421574
DOI: 10.1091/mbc.3.10.1181 -
ChemMedChem Dec 2022The Bis-T series of compounds comprise some of the most potent inhibitors of dynamin GTPase activity yet reported, e. g.,...
The Bis-T series of compounds comprise some of the most potent inhibitors of dynamin GTPase activity yet reported, e. g., (2E,2'E)-N,N'-(propane-1,3-diyl)bis(2-cyano-3-(3,4-dihydroxyphenyl)acrylamide) (2), Bis-T-22. The catechol moieties are believed to limit cell permeability, rendering these compounds largely inactive in cells. To solve this problem, a prodrug strategy was envisaged and eight ester analogues were synthesised. The shortest and bulkiest esters (acetate and butyl/tert-butyl) were found to be insoluble under physiological conditions, whilst the remaining five were soluble and stable under these conditions. These five were analysed for plasma stability and half-lives ranged from ∼2.3 min (propionic ester 4), increasing with size and bulk, to greater than 24 hr (dimethyl carbamate 10). Similar profiles where observed with the rate of formation of Bis-T-22 with half-lives ranging from ∼25 mins (propionic ester 4). Propionic ester 4 was chosen to undergo further testing and was found to inhibit endocytosis in a dose-dependent manner with IC ∼8 μM, suggesting this compound is able to effectively cross the cell membrane where it is rapidly hydrolysed to the desired Bis-T-22 parent compound.
Topics: Prodrugs; Dynamins; Esters; Endocytosis
PubMed: 36351775
DOI: 10.1002/cmdc.202200400