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Yang P, Sun X, Kou ZW, Wu KW, Huang YL, Sun FY. VEGF Axonal Transport Dependent on Kinesin-1B and Microtubules Dynamics. Front Mol Neurosci 2017; 10:424. [PMID: 29311814 PMCID: PMC5742618 DOI: 10.3389/fnmol.2017.00424] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Accepted: 12/05/2017] [Indexed: 01/19/2023] Open
Abstract
Axon-transport plays an important role in neuronal activity and survival. Reduced endogenous VEGF can cause neuronal damage and axon degeneration. It is unknown at this time if VEGF can be transported within the axon or whether it can be released by axonal depolarization. We transfected VEGF-eGFP plasmids in cultured hippocampal neurons and tracked their movement in the axons by live-cell confocal imaging. Then, we co-transfected phVEGF-eGFP and kinesin-1B-DsRed vectors into neurons and combined with immunoprecipitation and two-color imaging to study the mechanism of VEGF axon-trafficking. We found that VEGF vesicles morphologically co-localized and biochemically bounded with kinesin-1B, as well as co-trafficked with it in the axons. Moreover, the capacity for axonal trafficking of VEGF was reduced by administration of nocodazole, an inhibitor of microtubules, or kinesin-1B shRNA. In addition, we found that VEGF could release from the cultured neurons under acute depolarizing stimulation with potassium chloride. Therefore, present findings suggest that neuronal VEGF is stored in the vesicles, actively released, and transported in the axons, which depends on the presence of kinesin-1B and functional microtubules. These results further help us to understand the importance of neuronal VEGF in the maintenance of neuronal activity and survival throughout life.
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Affiliation(s)
- Ping Yang
- Department of Neurobiology, Institute for Biomedical Science and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Xiao Sun
- Department of Neurobiology, Institute for Biomedical Science and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Zeng-Wei Kou
- Department of Neurobiology, Institute for Biomedical Science and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Kun-Wei Wu
- Department of Neurobiology, Institute for Biomedical Science and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Ya-Lin Huang
- Department of Neurobiology, Institute for Biomedical Science and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China
| | - Feng-Yan Sun
- Department of Neurobiology, Institute for Biomedical Science and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, China.,Research Center on Aging and Medicine, Fudan University, Shanghai, China
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2
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Abstract
Vesicles, organelles and other intracellular cargo are transported by kinesin and dynein motors, which move in opposite directions along microtubules. This bidirectional cargo movement is frequently described as a 'tug of war' between oppositely directed molecular motors attached to the same cargo. However, although many experimental and modelling studies support the tug-of-war paradigm, numerous knockout and inhibition studies in various systems have found that inhibiting one motor leads to diminished motility in both directions, which is a 'paradox of co-dependence' that challenges the paradigm. In an effort to resolve this paradox, three classes of bidirectional transport models--microtubule tethering, mechanical activation and steric disinhibition--are proposed, and a general mathematical modelling framework for bidirectional cargo transport is put forward to guide future experiments.
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Rovini A, Savry A, Braguer D, Carré M. Microtubule-targeted agents: When mitochondria become essential to chemotherapy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:679-88. [DOI: 10.1016/j.bbabio.2011.01.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 01/02/2011] [Accepted: 01/04/2011] [Indexed: 12/22/2022]
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Erez H, Spira ME. Local self-assembly mechanisms underlie the differential transformation of the proximal and distal cut axonal ends into functional and aberrant growth cones. J Comp Neurol 2008; 507:1019-30. [DOI: 10.1002/cne.21522] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Erez H, Malkinson G, Prager-Khoutorsky M, De Zeeuw CI, Hoogenraad CC, Spira ME. Formation of microtubule-based traps controls the sorting and concentration of vesicles to restricted sites of regenerating neurons after axotomy. ACTA ACUST UNITED AC 2007; 176:497-507. [PMID: 17283182 PMCID: PMC2063984 DOI: 10.1083/jcb.200607098] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transformation of a transected axonal tip into a growth cone (GC) is a critical step in the cascade leading to neuronal regeneration. Critical to the regrowth is the supply and concentration of vesicles at restricted sites along the cut axon. The mechanisms underlying these processes are largely unknown. Using online confocal imaging of transected, cultured Aplysia californica neurons, we report that axotomy leads to reorientation of the microtubule (MT) polarities and formation of two distinct MT-based vesicle traps at the cut axonal end. Approximately 100 microm proximal to the cut end, a selective trap for anterogradely transported vesicles is formed, which is the plus end trap. Distally, a minus end trap is formed that exclusively captures retrogradely transported vesicles. The concentration of anterogradely transported vesicles in the former trap optimizes the formation of a GC after axotomy.
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Affiliation(s)
- Hadas Erez
- Department of Neurobiology, Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem, Israel
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6
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Abstract
Organelle transport is vital for the development and maintenance of axons, in which the distances between sites of organelle biogenesis, function, and recycling or degradation can be vast. Movement of mitochondria in axons can serve as a general model for how all organelles move: mitochondria are easy to identify, they move along both microtubule and actin tracks, they pause and change direction, and their transport is modulated in response to physiological signals. However, they can be distinguished from other axonal organelles by the complexity of their movement and their unique functions in aerobic metabolism, calcium homeostasis and cell death. Mitochondria are thus of special interest in relating defects in axonal transport to neuropathies and degenerative diseases of the nervous system. Studies of mitochondrial transport in axons are beginning to illuminate fundamental aspects of the distribution mechanism. They use motors of one or more kinesin families, along with cytoplasmic dynein, to translocate along microtubules, and bidirectional movement may be coordinated through interaction between dynein and kinesin-1. Translocation along actin filaments is probably driven by myosin V, but the protein(s) that mediate docking with actin filaments remain unknown. Signaling through the PI 3-kinase pathway has been implicated in regulation of mitochondrial movement and docking in the axon, and additional mitochondrial linker and regulatory proteins, such as Milton and Miro, have recently been described.
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Affiliation(s)
- Peter J Hollenbeck
- Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA.
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7
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Glutamate and amyloid beta-protein rapidly inhibit fast axonal transport in cultured rat hippocampal neurons by different mechanisms. J Neurosci 2003. [PMID: 14523099 DOI: 10.1523/jneurosci.23-26-08967.2003] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Impairment of axonal transport leads to neurodegeneration and synapse loss. Glutamate and amyloid beta-protein (Abeta) have critical roles in the pathogenesis of Alzheimer's disease (AD). Here we show that both agents rapidly inhibit fast axonal transport in cultured rat hippocampal neurons. The effect of glutamate (100 microm), but not of Abeta25-35 (20 microm), was reversible, was mimicked by NMDA or AMPA, and was blocked by NMDA and AMPA antagonists and by removal of extracellular Ca2+. The effect of Abeta25-35 was progressive and irreversible, was prevented by the actin-depolymerizing agent latrunculin B, and was mimicked by the actin-polymerizing agent jasplakinolide. Abeta25-35 induced intracellular actin aggregation, which was prevented by latrunculin B. Abeta31-35 but not Abeta15-20 exerted effects similar to those of Abeta25-35. Full-length Abeta1-42 incubated for 7 d, which specifically contained 30-100 kDa molecular weight assemblies, also caused an inhibition of axonal transport associated with intracellular actin aggregation, whereas freshly dissolved Abeta1-40, incubated Abeta1-40, and fresh Abeta1-42 had no effect. These results suggest that glutamate inhibits axonal transport via activation of NMDA and AMPA receptors and Ca2+ influx, whereas Abeta exerts its inhibitory effect via actin polymerization and aggregation. The ability of Abeta to inhibit axonal transport seems to require active amino acid residues, which is probably present in the 31-35 sequence. Full-length Abeta may be effective when it represents a structure in which these active residues can access the cell membrane. Our results may provide insight into the early pathogenetic mechanisms of AD.
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Hiruma H, Katakura T, Takahashi S, Ichikawa T, Kawakami T. Glutamate and amyloid beta-protein rapidly inhibit fast axonal transport in cultured rat hippocampal neurons by different mechanisms. J Neurosci 2003; 23:8967-77. [PMID: 14523099 PMCID: PMC6740390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
Impairment of axonal transport leads to neurodegeneration and synapse loss. Glutamate and amyloid beta-protein (Abeta) have critical roles in the pathogenesis of Alzheimer's disease (AD). Here we show that both agents rapidly inhibit fast axonal transport in cultured rat hippocampal neurons. The effect of glutamate (100 microm), but not of Abeta25-35 (20 microm), was reversible, was mimicked by NMDA or AMPA, and was blocked by NMDA and AMPA antagonists and by removal of extracellular Ca2+. The effect of Abeta25-35 was progressive and irreversible, was prevented by the actin-depolymerizing agent latrunculin B, and was mimicked by the actin-polymerizing agent jasplakinolide. Abeta25-35 induced intracellular actin aggregation, which was prevented by latrunculin B. Abeta31-35 but not Abeta15-20 exerted effects similar to those of Abeta25-35. Full-length Abeta1-42 incubated for 7 d, which specifically contained 30-100 kDa molecular weight assemblies, also caused an inhibition of axonal transport associated with intracellular actin aggregation, whereas freshly dissolved Abeta1-40, incubated Abeta1-40, and fresh Abeta1-42 had no effect. These results suggest that glutamate inhibits axonal transport via activation of NMDA and AMPA receptors and Ca2+ influx, whereas Abeta exerts its inhibitory effect via actin polymerization and aggregation. The ability of Abeta to inhibit axonal transport seems to require active amino acid residues, which is probably present in the 31-35 sequence. Full-length Abeta may be effective when it represents a structure in which these active residues can access the cell membrane. Our results may provide insight into the early pathogenetic mechanisms of AD.
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Affiliation(s)
- Hiromi Hiruma
- Department of Physiology, Kitasato University School of Medicine, Sagamihara 228-8555, Japan.
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Delcroix JD, Valletta JS, Wu C, Hunt SJ, Kowal AS, Mobley WC. NGF signaling in sensory neurons: evidence that early endosomes carry NGF retrograde signals. Neuron 2003; 39:69-84. [PMID: 12848933 DOI: 10.1016/s0896-6273(03)00397-0] [Citation(s) in RCA: 358] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Target-derived NGF promotes the phenotypic maintenance of mature dorsal root ganglion (DRG) nociceptive neurons. Here, we provide in vivo and in vitro evidence for the presence within DRG neurons of endosomes containing NGF, activated TrkA, and signaling proteins of the Rap1/Erk1/2, p38MAPK, and PI3K/Akt pathways. Signaling endosomes were shown to be retrogradely transported in the isolated sciatic nerve in vitro. NGF injection in the peripheral target of DRG neurons increased the retrograde transport of p-Erk1/2, p-p38, and pAkt in these membranes. Conversely, NGF antibody injections decreased the retrograde transport of p-Erk1/2 and p-p38. Our results are evidence that signaling endosomes, with the characteristics of early endosomes, convey NGF signals from the target of nociceptive neurons to their cell bodies.
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Affiliation(s)
- Jean-Dominique Delcroix
- Department of Neurology and Neurological Sciences, Stanford University, Stanford 94305, USA.
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Vendrell J, Querol E, Avilés FX. Metallocarboxypeptidases and their protein inhibitors. Structure, function and biomedical properties. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1477:284-98. [PMID: 10708864 DOI: 10.1016/s0167-4838(99)00280-0] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Among the different aspects of recent progress in the field of metallocarboxypeptidases has been the elucidation of the three dimensional structures of the pro-segments (in monomeric or oligomeric species) and their role in the expression, folding and inhibition/activation of the pancreatic and pancreatic-like forms. Also of great significance has been the cloning and characterization of several new regulatory carboxypeptidases, enzymes that are related with important functions in protein and peptide processing and that show significant structural differences among them and also with the digestive ones. Many regulatory carboxypeptidases lack a pro-region, unlike the digestive forms or others in between from the evolutionary point of view. Finally, important advances have been made on the finding and characterization of new protein inhibitors of metallocarboxypeptidases, some of them with interesting potential applications in the biotechnological/biomedical fields. These advances are analyzed here and compared with the earlier observations in this field, which was first explored by Hans Neurath and collaborators.
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Affiliation(s)
- J Vendrell
- Departament de Bioquímica i Biologia Molecular, Facultat de Ciències, and Institut de Biologia Fonamental. Universitat Autònoma de Barcelona, E-08193, Bellaterra, Spain
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11
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Martin M, Iyadurai SJ, Gassman A, Gindhart JG, Hays TS, Saxton WM. Cytoplasmic dynein, the dynactin complex, and kinesin are interdependent and essential for fast axonal transport. Mol Biol Cell 1999; 10:3717-28. [PMID: 10564267 PMCID: PMC25669 DOI: 10.1091/mbc.10.11.3717] [Citation(s) in RCA: 304] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In axons, organelles move away from (anterograde) and toward (retrograde) the cell body along microtubules. Previous studies have provided compelling evidence that conventional kinesin is a major motor for anterograde fast axonal transport. It is reasonable to expect that cytoplasmic dynein is a fast retrograde motor, but relatively few tests of dynein function have been reported with neurons of intact organisms. In extruded axoplasm, antibody disruption of kinesin or the dynactin complex (a dynein activator) inhibits both retrograde and anterograde transport. We have tested the functions of the cytoplasmic dynein heavy chain (cDhc64C) and the p150(Glued) (Glued) component of the dynactin complex with the use of genetic techniques in Drosophila. cDhc64C and Glued mutations disrupt fast organelle transport in both directions. The mutant phenotypes, larval posterior paralysis and axonal swellings filled with retrograde and anterograde cargoes, were similar to those caused by kinesin mutations. Why do specific disruptions of unidirectional motor systems cause bidirectional defects? Direct protein interactions of kinesin with dynein heavy chain and p150(Glued) were not detected. However, strong dominant genetic interactions between kinesin, dynein, and dynactin complex mutations in axonal transport were observed. The genetic interactions between kinesin and either Glued or cDhc64C mutations were stronger than those between Glued and cDhc64C mutations themselves. The shared bidirectional disruption phenotypes and the dominant genetic interactions demonstrate that cytoplasmic dynein, the dynactin complex, and conventional kinesin are interdependent in fast axonal transport.
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Affiliation(s)
- M Martin
- Department of Biology, Indiana University, Bloomington, Indiana 47405-6801, USA
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12
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Morris RL, Hollenbeck PJ. Axonal transport of mitochondria along microtubules and F-actin in living vertebrate neurons. J Cell Biol 1995; 131:1315-26. [PMID: 8522592 PMCID: PMC2120647 DOI: 10.1083/jcb.131.5.1315] [Citation(s) in RCA: 410] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A large body of evidence indicates that microtubules (MTs) conduct organelle transport in axons, but recent studies on extruded squid axoplasm have suggested that actin microfilaments (MFs) may also play a role in this process. To investigate the separate contributions to transport of each class of cytoskeletal element in intact vertebrate axons, we have monitored mitochondrial movements in chick sympathetic neurons experimentally manipulated to eliminate MTs, MFs, or both. First, we grew neurons in the continuous presence of: (a) cytochalasin E to create neurites which had never contained MFs; or (b) nocodazole or vinblastine to produce neurites which had never contained MTs. Mitochondria moved bidirectionally at normal velocities along the length of neurites which contained MTs and lacked MFs, but did not even enter neurites grown without MTs but containing MFs. In a second approach, we treated established neuronal cultures with cytoskeletal drugs to disrupt either MTs or MFs in axons already containing mitochondria. In cytochalasin-treated cells, which retained MTs but lacked MFs, average mitochondrial velocity increased in both directions, but net directional transport decreased. In vinblastine-treated cells, which lacked MTs but retained essentially normal levels of MFs, mitochondria continued to move bidirectionally but the average mitochondrial velocity and excursion length were reduced for both directions of movement, and the mitochondria spent threefold as much time moving in the retrograde as in the anterograde direction, resulting in net retrograde transport. Treatment of established cultures with both drugs produced neurites lacking MTs and MFs but still rich in neurofilaments; these showed a striking absence of any mitochondrial motility. These data indicate that axonal organelle transport can occur along both MTs and MFs in vivo, but with different velocities and net transport properties.
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Affiliation(s)
- R L Morris
- Department of Neurobiology and Program in Biological and Biomedical Science, Harvard Medical School, Boston, Massachusetts 02115, USA
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13
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Meller K. Axoplasmic transport of horseradish peroxidase in single neurons of the dorsal root ganglion studied in vitro by microinjection. Cell Tissue Res 1992; 270:139-48. [PMID: 1384982 DOI: 10.1007/bf00381888] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The dependence of anterograde axoplasmic transport on cytoskeletal components was investigated using microinjection of horseradish peroxidase (HRP) into the somata of chick dorsal root ganglion cells in vitro. Microinjected HRP was transported anterogradely in the neurites and their branches; this transport was disturbed by colchicine in a drug-dependent and time-dependent manner. Cytochalasin B, a drug that depolymerizes actin, did not inhibit the transport of HRP, despite the formation of local swellings in neurites. The microinjection of polyclonal antibodies directed against tubulin and monoclonal antibodies (mAbs) against 200-kDa neurofilaments disturbed the axoplasmic transport of co-injected HRP, which then exhibited an irregular and discontinuous distribution in the axonal branches. The transport of HRP became discontinuous after the injection of anti-tubulin antibodies and led to the formation of globular deposits of HRP. Polyclonal antibodies against actin and mAbs to 160-kDa and 68-kDa neurofilaments seemed to have no effect on the axoplasmic transport of co-injected HRP. Microinjection of antibodies against tubulin induced formation of perinuclear bundles consisting of cytoskeletal components. The transport of HRP thus appears to be regulated by an intact microtubular system and cross-linker components (200-kDa neurofilaments) of the cytoskeleton. Actin and most intermediate filament proteins do not seem to play an essential role in the transport of HRP.
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Affiliation(s)
- K Meller
- Abteilung für Cytologie, Ruhr-Universität Bochum, Federal Republic of Germany
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Mizobuchi T, Yagi Y, Mizuno A. Changes in alpha-tubulin and actin gene expression during optic nerve regeneration in frog retina. J Neurochem 1990; 55:54-9. [PMID: 2355231 DOI: 10.1111/j.1471-4159.1990.tb08820.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The optic nerve of the bullfrog was transected and the regeneration process was investigated. We previously reported that alpha-tubulin mRNA in the retina increased to a maximum 1-2 h after optic nerve transection with no specific change in actin mRNA. In the present investigation, we examined the long-term effect of optic nerve transection. Northern blot analysis revealed that alpha-tubulin mRNA increased again gradually after the rapid and transient increase and actin mRNA increased to a maximum at 7 days (more than twofold compared to the control retinas). The period during which actin mRNA reaches a maximal increase almost corresponds to the time lag between the axotomy and the initiation of axonal outgrowth. The main cytoskeletons of neuronal growth cones have been shown to consist of actin-containing microfilaments. Therefore, the transient increase of actin mRNA may have a relationship to the initial outgrowth of axons. On the other hand, the rapid and transient increase of alpha-tubulin mRNA observed in our previous studies is probably one of the initial responses of retinal ganglion cells to the axotomy, and the gradual increase in alpha-tubulin mRNA observed in this study can probably be interpreted as provision of the structural materials necessary for axonal elongation.
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Affiliation(s)
- T Mizobuchi
- Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan
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15
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Edmonds BT, Koenig E. Transmembrane cytoskeletal modulation in preterminal growing axons: I. Arrest of bulk and organelle transport in goldfish retinal ganglion cell axons regenerating in vitro by lectins binding to sialoglycoconjugates. CELL MOTILITY AND THE CYTOSKELETON 1990; 17:106-17. [PMID: 2175257 DOI: 10.1002/cm.970170206] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Goldfish retinal ganglion cell (RGC) axons regenerating in vitro exhibit a novel mode of axoplasmic transport that entails a rapid bidirectional bulk redistribution of axoplasm, "packaged" as protruding varicosities and non-protruding phase-dense inclusions (Koenig et al.: J. Neurosci. 5:715-729, 1985; Edmonds and Koenig Brain Res. 406:288-293, 1987). We have used phase-contrast video microscopy to study transmembrane effects of surface-binding lectins on bulk transport and transport of single visible organelles in RGC axons. Our findings show that certain lectins which crosslink sialoglycoconjugates, such as wheat germ agglutinin (WGA) and the more specific sialic acid-binding lectin Limax flavus agglutinin (LFA), induce a rapid inhibition of transport activity. The LFA-induced inhibition of transport can be reversed by appropriate simple sugar haptens, and can also be antagonized by pretreatment with cytochalasin D. One of the consequences of LFA binding is an increase in RITC-conjugated phalloidin fluorescence staining of preterminal axons. The latter observation in conjunction with the antagonistic action of cytochalasin D suggests that one possible explanation for the transmembrane arrest of transport induced by crosslinking of surface sialoglycoconjugates may involve a polymerization and/or reorganization of the actin filament network which hinders translocation of mobile axoplasmic components.
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Affiliation(s)
- B T Edmonds
- Department of Physiology, University at Buffalo, New York
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16
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Okuhara K, Murofushi H, Sakai H. Binding of kinesin to stress fibers in fibroblasts under condition of microtubule depolymerization. CELL MOTILITY AND THE CYTOSKELETON 1989; 12:71-7. [PMID: 2540915 DOI: 10.1002/cm.970120202] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The localization of kinesin in EBTr (bovine embryonic trachea fibroblast) cells was studied by indirect immunofluorescence microscopy using an affinity-purified antibody against bovine adrenal kinesin. It has already been shown that in interphase cells a part of kinesin is located on microtubules and the rest diffusely distributed throughout the cytoplasm [Murofushi et al., 1988]. When microtubules were depolymerized with cold or colchicine treatment, antikinesin antibody-stained fibrous components distinct from microtubules. These fibrous structures were considered to be stress fibers because they were stained with rhodamine-phalloidin and because the fibrous staining with antikinesin antibody was completely lost by treating the cells with cytochalasin D along with colchicine. When cold-treated cells in which a major part of kinesin had been localized on stress fibers were incubated at 37 degrees C, kinesin reappeared on reconstituted microtubules. These observations strongly suggest that kinesin has affinity not only to microtubules but also to stress fibers in culture cells.
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Affiliation(s)
- K Okuhara
- Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan
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17
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Komiya Y, Tashiro T. Effects of taxol on slow and fast axonal transport. CELL MOTILITY AND THE CYTOSKELETON 1988; 11:151-6. [PMID: 2463106 DOI: 10.1002/cm.970110302] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Axonal transport of tubulin in the rat sciatic nerve is almost completely inhibited by a single subepineural injection of taxol, without affecting that of neurofilament proteins. Actin and a large number of polypeptides cotransported with actin as minor components are also blocked by taxol, although to a lesser extent. Fast axonal transport is essentially free from the inhibitory effect of this drug. Although previous models have suggested that slow axonal transport involves the bulk movement of cytoskeletal structures, these results suggest that such transport may involve an equilibrium between polymerised and depolymerised forms of the axonal cytoskeleton.
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Affiliation(s)
- Y Komiya
- Department of Biochemistry, University of Tokyo Faculty of Medicine, Japan
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18
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Letourneau PC, Shattuck TA, Ressler AH. "Pull" and "push" in neurite elongation: observations on the effects of different concentrations of cytochalasin B and taxol. CELL MOTILITY AND THE CYTOSKELETON 1987; 8:193-209. [PMID: 2891448 DOI: 10.1002/cm.970080302] [Citation(s) in RCA: 169] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Neurite elongation involves two distinct cytoskeletal functions the "push" of anterograde transport of the cytoskeleton and associated organelles to the neurite tip, and the "pull" exerted by protrusion and generation of tensions in the growth cone. We investigated the roles of these two activities in neurite elongation via the drugs taxol and cytochalasin B (CB), which act on the key cytoskeletal components, microtubules and actin filaments, respectively. When neurons are treated with concentrations of CB below 0.2 micrograms/ml, neurite elongation, growth cone protrusion, and neurite tension are all inhibited in a similar concentration dependent manner. Protrusive activity and tensions are absent at CB concentrations above 0.3 micrograms/ml, yet neurite elongation continues at a plateau level. Thus, "pull" does modulate, but it is not required for neurite elongation. Surprisingly, the inhibitory effects of taxol on neurite elongation are removed by the addition of CB at levels that substantially disrupt the actin filaments of neurites. The neurites extended by taxol-CB neurons are unbranched and curiously unattached to the substratum. When CB is added to taxol-treated neurons, neurite extension begins rapidly, even if protein synthesis is severely reduced. We propose that taxol inhibits microtubule transport in neurites, and this inhibition of "push" is reversed by the disruptive effects of CB on the cytoplasmic matrix, allowing taxol-induced microtubule bundles to be transported distally.
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Affiliation(s)
- P C Letourneau
- Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis 55455
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19
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Lavoie PA, Tiberi M. Inhibition of fast axonal transport in bullfrog nerves by dibenzazepine and dibenzocycloheptadiene calmodulin inhibitors. JOURNAL OF NEUROBIOLOGY 1986; 17:681-95. [PMID: 2432170 DOI: 10.1002/neu.480170611] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The effects of the calmodulin inhibitors amitriptyline, desipramine, imipramine, and clomipramine on fast axonal transport, oxidative metabolism, and density of axonal microtubules were measured in bullfrog spinal nerves in vitro. The four drugs tested inhibited the fast orthograde transport of [3H]leucine-labelled proteins and the fast retrograde transport of acetylcholinesterase at a concentration of 0.2 mM. Amitriptyline, desipramine, and imipramine were equipotent inhibitors of transport, and clomipramine was a more potent inhibitor than imipramine. The adenosine triphosphate content of the nerves was reduced by at most 19% by the compounds under study; such a reduction cannot account for the inhibition of fast axonal transport. Desipramine and imipramine had no significant effect on the density of microtubules in unmyelinated axons, whereas amitriptyline only reduced it by 18%; the inhibition of axonal transport by these three drugs can therefore not be explained by microtubule disruption. Clomipramine reduced microtubular density by 40%, and this effect may have contributed to the inhibition of fast axonal transport. The inhibition of fast axonal transport by desipramine, imipramine, and amitriptyline may be related to the inhibition of calmodulin function by these drugs. The similar potency of these three drugs as inhibitors of fast axonal transport goes in parallel with their known similar potency as calmodulin antagonists.
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Gilbert SP, Sloboda RD. Identification of a MAP 2-like ATP-binding protein associated with axoplasmic vesicles that translocate on isolated microtubules. J Biophys Biochem Cytol 1986; 103:947-56. [PMID: 3091608 PMCID: PMC2114312 DOI: 10.1083/jcb.103.3.947] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Axoplasmic vesicles were purified and observed to translocate on isolated microtubules in an ATP-dependent, trypsin-sensitive manner, implying that ATP-binding polypeptides essential for force generation were present on the vesicle surface. To identify these proteins [alpha 32P]8-azidoadenosine 5'-triphosphate ([alpha 32P]8-N3ATP), a photoaffinity analogue of ATP, was used. The results presented here identify and characterize a vesicle-associated polypeptide having a relative molecular mass of 292 kD that bound [alpha 32P]8-N3ATP. The incorporation of label is ultraviolet light-dependent and ATP-sensitive. Moreover, the 292-kD polypeptide could be isolated in association with vesicles or microtubules, depending on the conditions used, and the data indicate that the 292-kD polypeptide is similar to mammalian brain microtubule-associated protein 2 (MAP 2) for the following reasons: The 292-kD polypeptide isolated from either squid axoplasm or optic lobe cross-reacts with antiserum to porcine brain MAP 2. Furthermore, it purifies with taxol-stabilized microtubules and is released with salt. Based on these characteristics, the 292-kD polypeptide is distinct from the known force-generating molecules myosin and flagellar dynein, as well as the 110-130-kD kinesin-like polypeptides that have recently been described (Brady, S. T., 1985, Nature (Lond.), 317:73-75; Vale, R. D., T. S. Reese, and M. P. Sheetz, 1985b, Cell, 42:39-50; Scholey, J. M., M. E. Porter, P. M. Grissom, and J. R. McIntosh, 1985, Nature (Lond.), 318:483-486). Because the 292-kD polypeptide binds ATP and is associated with vesicles that translocate on purified MAP-free microtubules in an ATP-dependent fashion, it is therefore believed to be involved in vesicle-microtubule interactions that promote organelle motility.
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Abstract
The nervous system is a rich source of filamentous proteins that assume critical roles in determining and maintaining neuronal form and function. Neurons contain three major classes of these cytoskeletal organelles: microtubules, intermediate filaments, and microfilaments. They also contain a variety of proteins that organize them and serve to connect them with each other. Such major neurodegenerative diseases as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as a variety of toxic neuropathies, are characterized pathologically by intraneuronal filamentous inclusions. Recent studies using biochemical and immunocytochemical techniques have established that these abnormalities represent disorganized states of the neuronal cytoskeleton and have determined some of the specific molecular constituents of these inclusions. This knowledge has led to new ways of thinking about their origins.
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Abstract
Identification of the ATPase involved in fast axonal transport of membranous organelles has proven difficult. Myosin and dynein, other ATPases known to be involved in cell motility, have properties that are inconsistent with the established properties of fast axonal transport, an essential component of which is readily solubilized in physiological buffer conditions rather than being stably associated with either membranous organelles or cytoskeletal elements. Adenylyl imidodiphosphate (AMP-PNP), a nonhydrolysable analogue of ATP, is a potent inhibitor of fast axonal transport that results in a stable interaction of membranous organelles with microtubules. Here we report the identification and partial characterization of an ATPase activity from brain whose binding to microtubules is stabilized by AMP-PNP. This ATPase activity seems to be associated with a polypeptide of relative molecular mass (Mr) 130,000 that is highly enriched in microtubule pellets after incubation with AMP-PNP and a soluble fraction from chick brain. This novel ATPase fraction has the predicted characteristics of the motor involved in fast axonal transport. Common features between the ATPase and fast axonal transport include interaction with the cytoskeleton in the presence of AMP-PNP, ready extractability, no Ca2+ dependence and inhibition by EDTA.
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Allen RD, Weiss DG, Hayden JH, Brown DT, Fujiwake H, Simpson M. Gliding movement of and bidirectional transport along single native microtubules from squid axoplasm: evidence for an active role of microtubules in cytoplasmic transport. J Biophys Biochem Cytol 1985; 100:1736-52. [PMID: 2580845 PMCID: PMC2113850 DOI: 10.1083/jcb.100.5.1736] [Citation(s) in RCA: 375] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Native microtubules prepared from extruded and dissociated axoplasm have been observed to transport organelles and vesicles unidirectionally in fresh preparations and more slowly and bidirectionally in older preparations. Both endogenous and exogenous (fluorescent polystyrene) particles in rapid Brownian motion alight on and adhere to microtubules and are transported along them. Particles can switch from one intersecting microtubule to another and move in either direction. Microtubular segments 1 to 30 microns long, produced by gentle homogenization, glide over glass surfaces for hundreds of micrometers in straight lines unless acted upon by obstacles. While gliding they transport particles either in the same (forward) direction and/or in the backward direction. Particle movement and gliding of microtubule segments require ATP and are insensitive to taxol (30 microM). It appears, therefore, that the mechanisms producing the motive force are very closely associated with the native microtubule itself or with its associated proteins. Although these movements appear irreconcilable with several current theories of fast axoplasmic transport, in this article we propose two models that might explain the observed phenomena and, by extension, the process of fast axoplasmic transport itself. The findings presented and the possible mechanisms proposed for fast axoplasmic transport have potential applications across the spectrum of microtubule-based motility processes.
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Abstract
erythro-9-[3-(2-Hydroxynonyl)]adenine, an inhibitor of protein carboxylmethylation and dynein-ATPase activity, inhibited fast axonal transport in vitro in frog sciatic nerves. Its site of action might be associated with an ATPase on which transport depends, since specific carboxylmethylation inhibitors lacked effects on transport. The levels of high energy phosphates and protein synthesis were unaffected by the drug at a transport-inhibiting concentration, making disturbances due to metabolic effects less likely. An erythro-9-[3-(2-hydroxynonyl)]adenine-sensitive ATPase was looked for in various nerve fractions but has so far not been resolved.
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Schliwa M, Ezzell RM, Euteneuer U. erythro-9-[3-(2-Hydroxynonyl)]adenine is an effective inhibitor of cell motility and actin assembly. Proc Natl Acad Sci U S A 1984; 81:6044-8. [PMID: 6385006 PMCID: PMC391855 DOI: 10.1073/pnas.81.19.6044] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
erythro-9-[3-(2-Hydroxynonyl)]adenine (EHNA) has been reported previously to be an agent that arrests sperm motility by inhibiting the axonemal dynein ATPase activity and has been used to probe the involvement of putative cytoplasmic dyneins in mitosis and intracellular organelle transport. We report here that EHNA profoundly and reversibly affects several actin-dependent processes, both in vivo and in vitro. It induces dramatic changes in actin organization in cultured cells, inhibits cell translocation, blocks actin-dependent cytoplasmic streaming, interferes with actin-dependent gelation of cytoplasmic extracts, and inhibits actin assembly. Just as the cytochalasins, EHNA appears to be a highly effective inhibitor of actin-based motility, whose effects in complex biological systems should be interpreted with caution.
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Brady ST, Lasek RJ, Allen RD, Yin HL, Stossel TP. Gelsolin inhibition of fast axonal transport indicates a requirement for actin microfilaments. Nature 1984; 310:56-8. [PMID: 6204208 DOI: 10.1038/310056a0] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The actions of actin-based microfilaments in cell motility suggest a possible role in the mechanism of fast axonal transport, but the pharmacological data evaluating their role in this process are equivocal. Moreover, microfilaments are difficult to preserve and identify in ultrastructural studies, so the organization and function of axonal actin has remained uncertain. We have now evaluated the role of actin microfilaments in intracellular transport of membranous organelles using video-enhanced contrast microscopy and gelsolin to analyse fast axonal transport directly in isolated axoplasm from the squid giant axon. With this preparation it is possible to perfuse axoplasm with large molecules that do not cross the plasmalemma, while controlling cation levels. The 90,000-molecular weight protein gelsolin depolymerizes actin microfilaments in micromolar Ca2+, but not in the absence of Ca2+. Axonal transport of membranous organelles has previously been shown to be unaffected by levels of Ca2+ up to 10 microM. In the presence of EGTA, gelsolin has no effect on the movement of membranous organelles, but in the presence of 10 microM Ca2+ it completely blocks transport of all membranous organelles. No changes in the organization of the axoplasm were detected. These results and results using other probes for actin are consistent with the hypothesis that actin-based microfilaments are involved in the movement of membranous organelles in the axon.
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Clark TG, Rosenbaum JL. Energy requirements for pigment aggregation in fundulus melanophores. CELL MOTILITY 1984; 4:431-41. [PMID: 6509524 DOI: 10.1002/cm.970040604] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Teleost chromatophores are filled with individual pigment granules that rapidly aggregate to the cell center or become dispersed throughout the cytoplasm in response to environmental stimuli. Microtubules appear to be required for pigment aggregation (movement toward the cell center), and recent findings have suggested that a dynein-like ATPase may participate in force production. Based on previous studies, however, it has been argued that pigment aggregation does not require energy directly, a view that supports the involvement of an elastic component in granule movement. To examine this point further, we have reinvestigated the energy requirements for pigment aggregation using both intact cells and detergent-permeabilized cell models of Fundulus melanophores. Poisons of oxidative phosphorylation, namely, 2,4 dinitrophenol and NaCN, reversibly inhibit melanosome aggregation in response to adrenaline. Inhibition of movement results directly from depletion of intracellular ATP, since pigment translocation can be reactivated in permeabilized cells by the addition of exogenous ATP to the lysis buffer. Non-hydrolyzable analogues, including beta, gamma-imidoadenosine-5'-triphosphate (AMPPNP), beta, gamma-methylene adenosine-5'-triphosphate (AMPPCP), and ATP gamma S, will not substitute for ATP in reactivation of movement. Similarly, other nucleotides such as ADP, AMP, GTP, CTP, and ITP, have limited ability to support melanosome aggregation in metabolically poisoned cells subjected to detergent lysis. ATP itself has no effect on intact cells. These results indicate that melanosome aggregation is ATP-dependent and energy-driven, and are consistent with a role for a force-transducing ATPase in particle movement.
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Forman DS, Brown KJ, Promersberger MW, Adelman MR. Nucleotide specificity for reactivation of organelle movements in permeabilized axons. CELL MOTILITY 1984; 4:121-8. [PMID: 6203649 DOI: 10.1002/cm.970040205] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In a permeabilized axon model, exogenous ATP can reactivate intraaxonal saltatory organelle movements (microscopically visible manifestations of fast axonal transport). We have studied the dependence of the reactivated movements on the ATP concentration and have also examined the nucleotide specificity of the reactivation. Organelle transport was visualized in isolated lobster giant motor axons using Nomarski optics and video microscopy. The axons were permeabilized with saponin, and movement was reactivated with ATP or other nucleotides. Some slight movement was seen with ATP concentrations as low as 10 microM. The velocity and frequency of the reactivated transport increased with increasing ATP concentrations up to about 5 mM. Movement was also reactivated by deoxyadenosine triphosphate, but not by AMP-PNP (a nonhydrolyzable ATP analogue), ADP, or AMP. Although other nucleotides (CTP, GTP, UTP, ITP) could reactivate transport, movement equivalent to that produced by 0.1 mM ATP was only seen with tenfold or greater concentrations of the other nucleotides. This pattern of specificity is consistent with the hypothesis that a dynein-like ATPase, rather than a myosin, is involved in fast axonal transport.
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