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Nature Sep 1993Dynamin is a microtubule-binding protein with a microtubule-activated GTPase activity. The gene encoding dynamin is mutated in shibire, a Drosophila mutant defective in...
Dynamin is a microtubule-binding protein with a microtubule-activated GTPase activity. The gene encoding dynamin is mutated in shibire, a Drosophila mutant defective in endocytosis in nerve terminals and other cells. These observations place dynamin into two distinct functional contexts, suggesting roles in microtubule-based motility or in endocytosis. We report here that dynamin is identical to the neuronal phosphoprotein dephosphin (P96), originally identified by its stimulus-dependent dephosphorylation in nerve terminals. Dynamin is a protein doublet of M(r) 94 and 96K arising by alternative splicing of its primary transcript. In the nerve terminal, both forms of dynamin are phosphorylated by protein kinase C (PKC) and are quantitatively dephosphorylated on excitation. In vitro, dynamin is also phosphorylated by casein kinase II which inhibits PKC phosphorylation. Phosphorylation by PKC but not by casein kinase II enhances the GTPase activity of dynamin 12-fold. The dynamins are therefore a group of nerve terminal phosphoproteins whose GTPase is regulated by phosphorylation in parallel with synaptic vesicle recycling. The regulation of dynamin GTPase could serve as the trigger for the rapid endocytosis of synaptic vesicles after exocytosis.
Topics: Alternative Splicing; Amino Acid Sequence; Animals; Brain; Cloning, Molecular; Drosophila Proteins; Dynamins; GTP Phosphohydrolases; Molecular Sequence Data; Phosphorylation; Protein Kinase C; Rats; Synaptic Membranes
PubMed: 8371759
DOI: 10.1038/365163a0 -
British Journal of Pharmacology Dec 2019Accumulating evidence indicates that mitochondrial dynamics play an important role in the progressive deterioration of dopaminergic neurons. Andrographolide has been...
BACKGROUND AND PURPOSE
Accumulating evidence indicates that mitochondrial dynamics play an important role in the progressive deterioration of dopaminergic neurons. Andrographolide has been found to exert neuroprotective effects in several models of neurological diseases. However, the mechanism of how andrographolide protects neurons in Parkinson's disease (PD) remains not fully understood.
EXPERIMENTAL APPROACH
Behavioural experiments were performed to examine the effect of andrographolide in 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-PD mice. Mitochondrial mass and morphology were visualized using transmission electron microscopy (TEM). SH-SY5Y cells and primary mouse neurons were exposed to rotenone to mimic PD in vitro. Western blotting, co-immunoprecipitation and immunofluorescence were performed. The target protein of andrographolide was identified by biotin-andrographolide pulldown assay as well as drug affinity responsive target stability (DARTS), cellular thermal shift (CETSA), and surface plasmon resonance (SPR) assays.
KEY RESULTS
Andrographolide administration improved behavioural deficits and attenuated loss of dopaminergic neurons in MPTP-exposed mice and reduced cell death induced by rotenone in vitro. An increased mitochondrial mass, and decreased surface area were found in the striatum from MPTP-PD mice, as well as in rotenone-treated primary neurons and SH-SY5Y cells, while andrographolide treatment preserved mitochondrial mass and morphology. Dynamin-related protein 1 (DRP1) was identified as a target protein of andrographolide. Andrographolide bound to DRP1 and inhibited its GTPase activity, thereby preventing excessive mitochondria fission and neuronal damage in PD.
CONCLUSIONS AND IMPLICATIONS
Our findings suggest that andrographolide may protect neurons against rotenone- or MPTP-induced damage in vitro and in vivo through inhibiting mitochondrial fission.
Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Cell Line, Tumor; Cell Survival; Diterpenes; Dynamins; Humans; Mice; Mice, Inbred C57BL; Mitochondria; Mitochondrial Dynamics; Neuroprotective Agents; Parkinson Disease; Surface Plasmon Resonance
PubMed: 31389613
DOI: 10.1111/bph.14823 -
Biochimica Et Biophysica Acta.... Oct 2023Alzheimer's disease (AD) is a neurodegenerative disease that manifests its pathology through synaptic damage, mitochondrial abnormalities, microRNA deregulation,... (Review)
Review
Alzheimer's disease (AD) is a neurodegenerative disease that manifests its pathology through synaptic damage, mitochondrial abnormalities, microRNA deregulation, hormonal imbalance, increased astrocytes & microglia, accumulation of amyloid β (Aβ) and phosphorylated Tau in the brains of AD patients. Despite extensive research, the effective treatment of AD is still unknown. Tau hyperphosphorylation and mitochondrial abnormalities are involved in the loss of synapses, defective axonal transport and cognitive decline in patients with AD. Mitochondrial dysfunction is evidenced by enhanced mitochondrial fragmentation, impaired mitochondrial dynamics, mitochondrial biogenesis and defective mitophagy in AD. Hence, targeting mitochondrial proteins might be a promising therapeutic strategy in treating AD. Recently, dynamin-related protein 1 (Drp1), a mitochondrial fission protein, has gained attention due to its interactions with Aβ and hyperphosphorylated Tau, altering mitochondrial morphology, dynamics, and bioenergetics. These interactions affect ATP production in mitochondria. A reduction in Drp1 GTPase activity protects against neurodegeneration in AD models. This article provides a comprehensive overview of Drp1's involvement in oxidative damage, apoptosis, mitophagy, and axonal transport of mitochondria. We also highlighted the interaction of Drp1 with Aβ and Tau, which may contribute to AD progression. In conclusion, targeting Drp1 could be a potential therapeutic approach for preventing AD pathology.
Topics: Humans; Alzheimer Disease; Amyloid beta-Peptides; Dynamins; Mitochondria; Neurodegenerative Diseases
PubMed: 37392948
DOI: 10.1016/j.bbadis.2023.166798 -
The EMBO Journal Nov 2016The large GTPase dynamin is the first protein shown to catalyze membrane fission. Dynamin and its related proteins are essential to many cell functions, from endocytosis... (Review)
Review
The large GTPase dynamin is the first protein shown to catalyze membrane fission. Dynamin and its related proteins are essential to many cell functions, from endocytosis to organelle division and fusion, and it plays a critical role in many physiological functions such as synaptic transmission and muscle contraction. Research of the past three decades has focused on understanding how dynamin works. In this review, we present the basis for an emerging consensus on how dynamin functions. Three properties of dynamin are strongly supported by experimental data: first, dynamin oligomerizes into a helical polymer; second, dynamin oligomer constricts in the presence of GTP; and third, dynamin catalyzes membrane fission upon GTP hydrolysis. We present the two current models for fission, essentially diverging in how GTP energy is spent. We further discuss how future research might solve the remaining open questions presently under discussion.
Topics: Animals; Cell Membrane; Dynamins; Guanosine Triphosphate; Humans
PubMed: 27670760
DOI: 10.15252/embj.201694613 -
Current Opinion in Cell Biology Apr 2023Dynamin, a 100-kDa GTPase, is one of the most-characterized membrane fission machineries catalyzing vesicle release from plasma membrane during endocytosis. The human... (Review)
Review
Dynamin, a 100-kDa GTPase, is one of the most-characterized membrane fission machineries catalyzing vesicle release from plasma membrane during endocytosis. The human genome encodes three dynamins: DNM1, DNM2 and DNM3, with high amino acid similarity but distinct expression patterns. Ever since the discoveries of dynamin mutations associated with human diseases in 2005, dynamin has become a paradigm for studying pathogenic mechanisms of mutant proteins from the aspects of structural biology, cell biology, model organisms as well as therapeutic strategy development. Here, we review the diseases and pathogenic mechanisms caused by mutations of DNM1 and DNM2, focusing on the activity requirement and regulation of dynamins in different tissues.
Topics: Humans; Dynamin II; Dynamins; Mutation; GTP Phosphohydrolases; Endocytosis
PubMed: 37230036
DOI: 10.1016/j.ceb.2023.102174 -
The Journal of Biological Chemistry Dec 1994Dynamin is a GTP-binding protein thought to be involved in the early stages of endocytosis. Presently, it is not known how dynamin GTP binding and hydrolysis are related...
Dynamin is a GTP-binding protein thought to be involved in the early stages of endocytosis. Presently, it is not known how dynamin GTP binding and hydrolysis are related to its role in this process. We previously characterized the ability of acidic phospholipid vesicles and microtubules to strongly stimulate the GTPase activity of purified brain dynamin. In a further analysis of dynamin enzymatic properties, we have found that the increase of dynamin GTP hydrolysis in the presence of activating agent depends on enzyme concentration. At low enzyme concentration, little or no activation is observed. Plots of dynamin GTPase activity with increasing enzyme concentration in the presence of either activating agent are strongly sigmoidal, indicating that positive cooperativity is responsible for the increased activity observed. A Hill coefficient of 2.3 was determined, implying that at least two dynamin molecules associate for maximal GTPase activity. No cooperative effects in GTP binding were observed. Linear transformation of reaction velocity versus enzyme concentration data indicate an apparent Km for dynamin-dynamin interactions of 37 nM, which is significantly lower than the physiological concentration of dynamin in brain. These results suggest that cooperative interactions between dynamin molecules are responsible for the apparent activation of GTPase observed and are likely involved in dynamin function in vivo.
Topics: Animals; Dynamins; Enzyme Activation; GTP Phosphohydrolases; Hydrolysis; Male; Microtubules; Rats; Rats, Sprague-Dawley; Substrate Specificity
PubMed: 7983015
DOI: No ID Found -
Autophagy Nov 2019The ubiquitination of mitochondrial proteins labels damaged mitochondria for degradation through mitophagy. We recently developed an system in which mitophagy is slowed...
The ubiquitination of mitochondrial proteins labels damaged mitochondria for degradation through mitophagy. We recently developed an system in which mitophagy is slowed by inhibiting mitochondrial division through knockout of , a dynamin related GTPase that mediates mitochondrial division. Using this system, we revealed that the ubiquitination of mitochondrial proteins required SQSTM1/p62, but not the ubiquitin E3 ligase PRKN/parkin, during mitophagy. Here, we tested the role of PINK1, a mitochondrial protein kinase that activates mitophagy by phosphorylating ubiquitin, in mitochondrial ubiquitination by knocking out in -knockout liver. We found mitochondrial ubiquitination did not decrease in the absence of PINK1; instead, PINK1 was required for the degradation of MFN1 (mitofusin 1) and MFN2, two homologous outer membrane proteins that mediate mitochondrial fusion in -knockout hepatocytes. These data suggest that mitochondrial ubiquitination is promoted by SQSTM1 independently of PINK1 and PRKN during mitophagy. PINK1 and PRKN appear to control the balance between mitochondrial division and fusion . DNM1L/DRP1: dynamin 1-like; KEAP1: kelch-like ECH-associated protein 1; KO: knockout; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MFN1/2: mitofusin 1/2; OPA1: OPA1, mitochondrial dynamin like GTPase; PDH: pyruvate dehydrogenase E1; PINK1: PTEN induced putative kinase 1; PRKN/parkin: parkin RBR E3 ubiquitin protein ligase.
Topics: Animals; Dynamins; GTP Phosphohydrolases; Hepatocytes; Mice; Mitochondria; Mitochondrial Dynamics; Mitophagy; Protein Kinases; Sequestosome-1 Protein; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 31339428
DOI: 10.1080/15548627.2019.1643185 -
Current Opinion in Cell Biology Aug 2002The GTPase dynamin is essential for endocytosis, but its mechanism of action remains uncertain. Structures of its GTPase domain, as well as that of assembled dynamin,... (Review)
Review
The GTPase dynamin is essential for endocytosis, but its mechanism of action remains uncertain. Structures of its GTPase domain, as well as that of assembled dynamin, have led to major advances in understanding the structural basis of its mode of action. Novel data point more clearly than ever towards a role for this protein in the actin cytoskeleton, mitogen-activated protein kinase signaling and apoptosis, suggesting that dynamin might be a signaling GTPase.
Topics: Animals; Dynamins; Endocytosis; GTP Phosphohydrolases; Humans; Molecular Structure; Protein Conformation; Protein Structure, Tertiary
PubMed: 12383797
DOI: 10.1016/s0955-0674(02)00347-2 -
Current Opinion in Cell Biology Aug 2023Endocytic dynamins self-assemble into helical scaffolds and utilize energy from GTP hydrolysis to constrict and sever tubular membranous necks of budded endocytic... (Review)
Review
Endocytic dynamins self-assemble into helical scaffolds and utilize energy from GTP hydrolysis to constrict and sever tubular membranous necks of budded endocytic intermediates. They bind the membrane using a pleckstrin-homology domain (PHD). The PHD is characterized by four unstructured loops, two of which partially insert into the membrane. Recent studies reveal that loop insertion lowers the bending rigidity of the membrane and that mutations in these two loops produce separable and opposite effects on the efficiency of dynamin-catalyzed membrane fission. Here, we review the current understanding of dynamin-catalyzed membrane fission and attempt to reconcile contrasting notions that have emerged from biochemical and cellular studies evaluating the role of the PHD in this process. We propose that two membrane-inserting loops act as "gears" that define the catalytic efficiency of the dynamin helical scaffold in membrane fission.
Topics: Cell Membrane; Dynamins; Mutation; Catalysis; Guanosine Triphosphate
PubMed: 37451176
DOI: 10.1016/j.ceb.2023.102204 -
Cytoskeleton (Hoboken, N.J.) Sep 2022Microtubule stability and dynamics regulations are essential for vital cellular processes, such as microtubule-dependent axonal transport. Dynamin is involved in many...
Microtubule stability and dynamics regulations are essential for vital cellular processes, such as microtubule-dependent axonal transport. Dynamin is involved in many membrane fission events, such as clathrin-mediated endocytosis. The ubiquitously expressed dynamin-2 has been reported to regulate microtubule stability. However, the underlying molecular mechanisms remain unclear. This study aimed to investigate the roles of intrinsic properties of dynamin-2 on microtubule regulation by rescue experiments. A heterozygous DNM2 mutation in HeLa cells was generated, and an increase in the level of stabilized microtubules in these heterozygous cells was observed. The expression of wild-type dynamin-2 in heterozygous cells reduced stabilized microtubules. Conversely, the expression of self-assembly-defective mutants of dynamin-2 in the heterozygous cells failed to decrease stabilized microtubules. This indicated that the self-assembling ability of dynamin-2 is necessary for regulating microtubule stability. Moreover, the heterozygous cells expressing the GTPase-defective dynamin-2 mutant, K44A, reduced microtubule stabilization, similar to the cells expressing wild-type dynamin-2, suggesting that GTPase activity of dynamin-2 is not essential for regulating microtubule stability. These results showed that the mechanism of microtubule regulation by dynamin-2 is diverse from that of endocytosis.
Topics: Humans; Dynamins; Endocytosis; GTP Phosphohydrolases; HeLa Cells; Microtubules
PubMed: 36053962
DOI: 10.1002/cm.21723