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Luo X, Zhang J, Tolö J, Kügler S, Michel U, Bähr M, Koch JC. Axonal autophagic vesicle transport in the rat optic nerve in vivo under normal conditions and during acute axonal degeneration. Acta Neuropathol Commun 2024; 12:82. [PMID: 38812004 PMCID: PMC11134632 DOI: 10.1186/s40478-024-01791-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 05/08/2024] [Indexed: 05/31/2024] Open
Abstract
Neurons pose a particular challenge to degradative processes like autophagy due to their long and thin processes. Autophagic vesicles (AVs) are formed at the tip of the axon and transported back to the soma. This transport is essential since the final degradation of the vesicular content occurs only close to or in the soma. Here, we established an in vivo live-imaging model in the rat optic nerve using viral vector mediated LC3-labeling and two-photon-microscopy to analyze axonal transport of AVs. Under basal conditions in vivo, 50% of the AVs are moving with a majority of 85% being transported in the retrograde direction. Transport velocity is higher in the retrograde than in the anterograde direction. A crush lesion of the optic nerve results in a rapid breakdown of retrograde axonal transport while the anterograde transport stays intact over several hours. Close to the lesion site, the formation of AVs is upregulated within the first 6 h after crush, but the clearance of AVs and the levels of lysosomal markers in the adjacent axon are reduced. Expression of p150Glued, an adaptor protein of dynein, is significantly reduced after crush lesion. In vitro, fusion and colocalization of the lysosomal marker cathepsin D with AVs are reduced after axotomy. Taken together, we present here the first in vivo analysis of axonal AV transport in the mammalian CNS using live-imaging. We find that axotomy leads to severe defects of retrograde motility and a decreased clearance of AVs via the lysosomal system.
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Affiliation(s)
- Xiaoyue Luo
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - Jiong Zhang
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - Johan Tolö
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - Sebastian Kügler
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - Uwe Michel
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - Mathias Bähr
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany
| | - Jan Christoph Koch
- Department of Neurology, University Medicine Göttingen, Göttingen, Germany.
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Mystery of methamphetamine-induced autophagosome accumulation in hippocampal neurons: loss of syntaxin 17 in defects of dynein-dynactin driving and autophagosome-late endosome/lysosome fusion. Arch Toxicol 2021; 95:3263-3284. [PMID: 34374793 DOI: 10.1007/s00204-021-03131-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 08/04/2021] [Indexed: 01/07/2023]
Abstract
Methamphetamine (METH), a psychoactive-stimulant facilitates massive accumulation of autophagosomes and causes autophagy-associated neuronal death. However, the underlying mechanisms involving METH-induced auto-phagosome accumulation remain poorly understood. In the current study, autophagic flux was tracked by mRFP-GFP-LC3 adenovirus, 900 μM METH treatment was found to significantly disrupt autophagic flux, which was further validated by remarkable increase of co-localized of LC3 and SQSTM1/p62, enhancement of LC3-II and SQSTM1/p62 protein levels, and massive autophagosome puncta aggregation. With the cycloheximide (CHX) treatment, METH treatment was displayed a significant inhibition of SQSTM1/p62 degradation. Therefore, the mRNAs associated with vesicle degradation were screened, and syntaxin 17 (Stx17) and dynein-dynactin mRNA levels significantly decreased, an effect was proved in protein level as well. Intriguingly, METH induced autophagosome accumulation and autophagic flux disturbance was incredibly retarded by overexpression of Stx17, which was validated by the restoration of the fusion autophagosome-late endosome/lysosome fusion. Moreover, Stx17 overexpression obviously impeded the METH-induced decrease of co-localization of the retrograded motor protein dynein/dynactin and autophagosome-late endosome, though the dynein/dynactin proteins were not involved in autophagosome-late endosome/lysosome fusion. Collectively, our findings unravel the mechanism of METH-induced autophagosome accumulation involving autophagosome-late endosome/lysosome fusion deficiency and that autophagy-enhancing mechanisms such as the overexpression of Stx17 may be therapeutic strategies for the treatment of METH-induced neuronal damage.
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Saito K, Murayama T, Hata T, Kobayashi T, Shibata K, Kazuno S, Fujimura T, Sakurai T, Toyoshima YY. Conformational diversity of dynactin sidearm and domain organization of its subunit p150. Mol Biol Cell 2020; 31:1218-1231. [PMID: 32238103 PMCID: PMC7353146 DOI: 10.1091/mbc.e20-01-0031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Dynactin is a principal regulator of the minus-end directed microtubule motor dynein. The sidearm of dynactin is essential for binding to microtubules and regulation of dynein activity. Although our understanding of the structure of the dynactin backbone (Arp1 rod) has greatly improved recently, structural details of the sidearm subcomplex remain elusive. Here, we report the flexible nature and diverse conformations of dynactin sidearm observed by electron microscopy. Using nanogold labeling and deletion mutant analysis, we determined the domain organization of the largest subunit p150 and discovered that its coiled-coil (CC1), dynein-binding domain, adopted either a folded or an extended form. Furthermore, the entire sidearm exhibited several characteristic forms, and the equilibrium among them depended on salt concentrations. These conformational diversities of the dynactin complex provide clues to understanding how it binds to microtubules and regulates dynein.
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Affiliation(s)
- Kei Saito
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | - Takashi Murayama
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Tomone Hata
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | - Takuya Kobayashi
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Keitaro Shibata
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
| | - Saiko Kazuno
- Laboratory of Proteomics and Biomolecular Science, Biomedical Research Center, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Tsutomu Fujimura
- Laboratory of Proteomics and Biomolecular Science, Biomedical Research Center, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Yoko Y Toyoshima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan.,Komaba Institute for Science, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan
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4
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Omer S, Greenberg SR, Lee WL. Cortical dynein pulling mechanism is regulated by differentially targeted attachment molecule Num1. eLife 2018; 7:36745. [PMID: 30084355 PMCID: PMC6080947 DOI: 10.7554/elife.36745] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 07/05/2018] [Indexed: 12/17/2022] Open
Abstract
Cortical dynein generates pulling forces via microtubule (MT) end capture-shrinkage and lateral MT sliding mechanisms. In Saccharomyces cerevisiae, the dynein attachment molecule Num1 interacts with endoplasmic reticulum (ER) and mitochondria to facilitate spindle positioning across the mother-bud neck, but direct evidence for how these cortical contacts regulate dynein-dependent pulling forces is lacking. We show that loss of Scs2/Scs22, ER tethering proteins, resulted in defective Num1 distribution and loss of dynein-dependent MT sliding, the hallmark of dynein function. Cells lacking Scs2/Scs22 performed spindle positioning via MT end capture-shrinkage mechanism, requiring dynein anchorage to an ER- and mitochondria-independent population of Num1, dynein motor activity, and CAP-Gly domain of dynactin Nip100/p150Glued subunit. Additionally, a CAAX-targeted Num1 rescued loss of lateral patches and MT sliding in the absence of Scs2/Scs22. These results reveal distinct populations of Num1 and underline the importance of their spatial distribution as a critical factor for regulating dynein pulling force. Cells must divide so that organisms can grow, repair damaged tissues or reproduce. Before dividing, a cell creates two identical copies of its genetic information – one for each daughter. A molecular machine known as the mitotic spindle then moves each set of genetic material to where it will be needed when the daughter cells form. For the process to work properly, however, a motor protein known as dynein must correctly position the spindle by pulling it into place from the outskirts of the cell. When a baker’s yeast cell divides, it first forms a ‘bump’, which grows into a bud that will ultimately become another yeast. The spindle needs to be precisely placed at the midpoint between the original cell and the bud, so the genetic material can get into the future daughter cell. To do so, dynein travels to the bud, where a protein called Num1 helps it attach to the periphery and pull the filaments of the mitotic spindle (known as microtubules) to the correct position. Num1 also attaches to other cellular structures in the bud, including one known as the endoplasmic reticulum. It was unclear how this connection changes where dynein is located, and how it can pull on the spindle. To study this, Omer et al. labeled Num1, dynein and microtubules with fluorescent markers so they could be followed in living baker’s yeast using time-lapse microscopy. Mutant yeast strains were also used to disrupt how these proteins associate, which helps to tease out their roles. The experiments show that there are several populations of Num1 in the bud. One associates with the endoplasmic reticulum, and it helps dynein grab the side of a microtubule and make it slide into the bud. The other does not attach to the reticulum, but instead is located at the very tip of the bud. There, it makes dynein capture the end of the microtubule; this destabilizes the filament, which starts to shorten. As the microtubule shrinks, the spindle is pulled closer to the bud’s tip, which aligns it in the right position. The yeast cells thus need Num1 in both locations to fine-tune the pulling activity of dynein, and the spindle’s final positioning. In the human body, not all divisions create two identical cells; for example, the daughters of stem cells can have different fates. This is due to a precise asymmetric division which dynein partly controls. The results by Omer et al. could help to unravel this mechanism.
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Affiliation(s)
- Safia Omer
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, United States
| | - Samuel R Greenberg
- Department of Biological Sciences, Dartmouth College, Hanover, United States
| | - Wei-Lih Lee
- Department of Biological Sciences, Dartmouth College, Hanover, United States
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Peptides mediating DNA transport on microtubules and their impact on non-viral gene transfer efficiency. Biosci Rep 2017; 37:BSR20170995. [PMID: 28899926 PMCID: PMC5643739 DOI: 10.1042/bsr20170995] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/05/2017] [Accepted: 09/07/2017] [Indexed: 11/17/2022] Open
Abstract
Synthetic vectors such as cationic polymers and cationic lipids remain attractive tools for non-viral gene transfer which is a complex process whose effectiveness relies on the ability to deliver a plasmid DNA (pDNA) into the nucleus of non-dividing cells. Once in the cytosol, the transport of pDNAs towards the nuclear envelope is strongly impaired by their very low cytosolic mobility due to their large size. To promote their movement towards the cell nucleus, few strategies have been implemented to exploit dynein, the microtubule’s (MT’s) motor protein, for propagation of cytosolic pDNA along the MTs towards the cell nucleus. In the first part of this review, an overview on MTs, dynein, dynein/virus interaction feature is presented followed by a summary of the results obtained by exploitation of LC8 and TCTEL1 dynein light chain association sequence (DLC-AS) for non-viral transfection. The second part dedicated to the adenoviral protein E3-14.7K, reports the transfection efficiency of polyplexes and lipoplexes containing the E3-14.7K-derived P79-98 peptide linked to pDNA. Here, several lines of evidence are given showing that dynein can be targeted to improve cytosolic pDNA mobility and accumulate pDNA near nuclear envelope in order to facilitate its transport through the nuclear pores. The linkage of various DLC-AS to pDNA carriers led to modest transfection improvements and their direct interaction with MTs was not demonstrated. In contrast, pDNA linked to the P79-98 peptide interacting with TCTEL1 via a cytosolic protein (fourteen seven K-interacting protein-1 (FIP-1)), interaction with MTs is evidenced in cellulo and transfection efficiency is improved.
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Kobayashi T, Miyashita T, Murayama T, Toyoshima YY. Dynactin has two antagonistic regulatory domains and exerts opposing effects on dynein motility. PLoS One 2017; 12:e0183672. [PMID: 28850609 PMCID: PMC5574551 DOI: 10.1371/journal.pone.0183672] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 07/31/2017] [Indexed: 01/01/2023] Open
Abstract
Dynactin is a dynein-regulating protein that increases the processivity of dynein movement on microtubules. Recent studies have shown that a tripartite complex of dynein–dynactin–Bicaudal D2 is essential for highly processive movement. To elucidate the regulation of dynein motility by dynactin, we focused on two isoforms (A and B) of dynactin 1 (DCTN1), the largest subunit of dynactin that contains both microtubule- and dynein-binding domains. The only difference between the primary structures of the two isoforms is that DCTN1B lacks the K-rich domain, a cluster of basic residues. We measured dynein motility by single molecule observation of recombinant dynein and dynactin. Whereas the tripartite complex containing DCTN1A exhibited highly processive movement, the complex containing DCTN1B dissociated from microtubules with no apparent processive movement. This inhibitory effect of DCTN1B was caused by reductions of the microtubule-binding affinities of both dynein and dynactin, which was attributed to the coiled-coil 1 domain of DCTN1. In DCTN1A, the K-rich domain antagonized these inhibitory effects. Therefore, dynactin has two antagonistic domains and promotes or suppresses dynein motility to accomplish correct localization and functions of dynein within a cell.
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Affiliation(s)
- Takuya Kobayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Takuya Miyashita
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Takashi Murayama
- Department of Pharmacology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Yoko Y. Toyoshima
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
- * E-mail:
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7
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Structural basis for the extended CAP-Gly domains of p150(glued) binding to microtubules and the implication for tubulin dynamics. Proc Natl Acad Sci U S A 2014; 111:11347-52. [PMID: 25059720 DOI: 10.1073/pnas.1403135111] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
p150(glued) belongs to a group of proteins accumulating at microtubule plus ends (+TIPs). It plays a key role in initiating retrograde transport by recruiting and tethering endosomes and dynein to microtubules. p150(glued) contains an N-terminal microtubule-binding cytoskeleton-associated protein glycine-rich (CAP-Gly) domain that accelerates tubulin polymerization. Although this copolymerization is well-studied using light microscopic techniques, structural consequences of this interaction are elusive. Here, using electron-microscopic and spectroscopic approaches, we provide a detailed structural view of p150(glued) CAP-Gly binding to microtubules and tubulin. Cryo-EM 3D reconstructions of p150(glued)-CAP-Gly complexed with microtubules revealed the recognition of the microtubule surface, including tubulin C-terminal tails by CAP-Gly. These binding surfaces differ from other retrograde initiation proteins like EB1 or dynein, which could facilitate the simultaneous attachment of all accessory components. Furthermore, the CAP-Gly domain, with its basic extensions, facilitates lateral and longitudinal interactions of tubulin molecules by covering the tubulin acidic tails. This shielding effect of CAP-Gly and its basic extensions may provide a molecular basis of the roles of p150(glued) in microtubule dynamics.
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Cytoplasmic dynein: a key player in neurodegenerative and neurodevelopmental diseases. SCIENCE CHINA-LIFE SCIENCES 2014; 57:372-7. [PMID: 24664850 DOI: 10.1007/s11427-014-4639-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 02/25/2014] [Indexed: 01/24/2023]
Abstract
Cytoplasmic dynein is the most important molecular motor driving the movement of a wide range of cargoes towards the minus ends of microtubules. As a molecular motor protein, dynein performs a variety of basic cellular functions including organelle transport and centrosome assembly. In the nervous system, dynein has been demonstrated to be responsible for axonal retrograde transport. Many studies have revealed direct or indirect evidence of dynein in neurodegenerative diseases such as amyotrophic lateral sclerosis, Charcot-Marie-Tooth disease, Alzheimer's disease, Parkinson's disease and Huntington's disease. Among them, a number of mutant proteins involved in various neurodegenerative diseases interact with dynein. Axonal transport disruption is presented as a common feature occurring in neurodegenerative diseases. Dynein heavy chain mutant mice also show features of neurodegenerative diseases. Moreover, defects of dynein-dependent processes such as autophagy or clearance of aggregation-prone proteins are found in most of these diseases. Lines of evidence have also shown that dynein is associated with neurodevelopmental diseases. In this review, we focus on dynein involvement in different neurological diseases and discuss potential underlying mechanisms.
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Lazarus JE, Moughamian AJ, Tokito MK, Holzbaur ELF. Dynactin subunit p150(Glued) is a neuron-specific anti-catastrophe factor. PLoS Biol 2013; 11:e1001611. [PMID: 23874158 PMCID: PMC3712912 DOI: 10.1371/journal.pbio.1001611] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 05/31/2013] [Indexed: 01/25/2023] Open
Abstract
The dynein partner dynactin not only binds to microtubules, but is found to potently influence microtubule dynamics in neurons. Regulation of microtubule dynamics in neurons is critical, as defects in the microtubule-based transport of axonal organelles lead to neurodegenerative disease. The microtubule motor cytoplasmic dynein and its partner complex dynactin drive retrograde transport from the distal axon. We have recently shown that the p150Glued subunit of dynactin promotes the initiation of dynein-driven cargo motility from the microtubule plus-end. Because plus end-localized microtubule-associated proteins like p150Glued may also modulate the dynamics of microtubules, we hypothesized that p150Glued might promote cargo initiation by stabilizing the microtubule track. Here, we demonstrate in vitro using assembly assays and TIRF microscopy, and in primary neurons using live-cell imaging, that p150Glued is a potent anti-catastrophe factor for microtubules. p150Glued alters microtubule dynamics by binding both to microtubules and to tubulin dimers; both the N-terminal CAP-Gly and basic domains of p150Glued are required in tandem for this activity. p150Glued is alternatively spliced in vivo, with the full-length isoform including these two domains expressed primarily in neurons. Accordingly, we find that RNAi of p150Glued in nonpolarized cells does not alter microtubule dynamics, while depletion of p150Glued in neurons leads to a dramatic increase in microtubule catastrophe. Strikingly, a mutation in p150Glued causal for the lethal neurodegenerative disorder Perry syndrome abrogates this anti-catastrophe activity. Thus, we find that dynactin has multiple functions in neurons, both activating dynein-mediated retrograde axonal transport and enhancing microtubule stability through a novel anti-catastrophe mechanism regulated by tissue-specific isoform expression; disruption of either or both of these functions may contribute to neurodegenerative disease. Microtubules are polymers of tubulin that undergo successive cycles of growth and shrinkage so that the cell can maintain a stable yet adaptable cytoskeleton. In neurons, the microtubule motor protein dynein and its partner complex dynactin drive retrograde transport along microtubules from the distal axon towards the cell body. In addition to binding to dynein, the p150Glued subunit of dynactin independently binds directly to microtubules. We hypothesized that by binding to microtubules, p150Glued might also alter microtubule dynamics. We demonstrate using biochemistry and microscopy in vitro and in cells that p150Glued stabilizes microtubules by inhibiting the transition from growth to shrinkage. We show that specific domains of p150Glued encoded by neuronally enriched splice-forms are necessary for this activity. Although depletion of p150Glued in nonpolarized cells does not alter microtubule dynamics, depletion of endogenous p150Glued in neurons leads to dramatic microtubule instability. Strikingly, a mutation in p150Glued known to cause the neurodegenerative disorder Perry syndrome abolishes this activity. In summary, we identified a previously unappreciated function of dynactin in direct regulation of the microtubule cytoskeleton. This activity may enhance generic microtubule stability in the cell, but could be especially important in specific areas of the cell where dynactin and dynein are loaded onto microtubules.
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Affiliation(s)
- Jacob E. Lazarus
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Armen J. Moughamian
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Mariko K. Tokito
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Erika L. F. Holzbaur
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Kulkarni VA, Firestein BL. The dendritic tree and brain disorders. Mol Cell Neurosci 2012; 50:10-20. [DOI: 10.1016/j.mcn.2012.03.005] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 03/09/2012] [Indexed: 01/21/2023] Open
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Abstract
The organization and function of eukaryotic cells rely on the action of many different molecular motor proteins. Cytoplasmic dynein drives the movement of a wide range of cargoes towards the minus ends of microtubules, and these events are needed, not just at the single-cell level, but are vital for correct development. In the present paper, I review recent progress on understanding dynein's mechanochemistry, how it is regulated and how it binds to such a plethora of cargoes. The importance of a number of accessory factors in these processes is discussed.
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Minoura I, Katayama E, Sekimoto K, Muto E. One-dimensional Brownian motion of charged nanoparticles along microtubules: a model system for weak binding interactions. Biophys J 2010; 98:1589-97. [PMID: 20409479 DOI: 10.1016/j.bpj.2009.12.4323] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 12/24/2009] [Accepted: 12/29/2009] [Indexed: 10/19/2022] Open
Abstract
Various proteins are known to exhibit one-dimensional Brownian motion along charged rodlike polymers, such as microtubules (MTs), actin, and DNA. The electrostatic interaction between the proteins and the rodlike polymers appears to be crucial for one-dimensional Brownian motion, although the underlying mechanism has not been fully clarified. We examined the interactions of positively-charged nanoparticles composed of polyacrylamide gels with MTs. These hydrophilic nanoparticles bound to MTs and displayed one-dimensional Brownian motion in a charge-dependent manner, which indicates that nonspecific electrostatic interaction is sufficient for one-dimensional Brownian motion. The diffusion coefficient decreased exponentially with an increasing particle charge (with the exponent being 0.10 kBT per charge), whereas the duration of the interaction increased exponentially (exponent of 0.22 kBT per charge). These results can be explained semiquantitatively if one assumes that a particle repeats a cycle of binding to and movement along an MT until it finally dissociates from the MT. During the movement, a particle is still electrostatically constrained in the potential valley surrounding the MT. This entire process can be described by a three-state model analogous to the Michaelis-Menten scheme, in which the two parameters of the equilibrium constant between binding and movement, and the rate of dissociation from the MT, are derived as a function of the particle charge density. This study highlights the possibility that the weak binding interactions between proteins and rodlike polymers, e.g., MTs, are mediated by a similar, nonspecific charge-dependent mechanism.
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Affiliation(s)
- Itsushi Minoura
- Laboratory for Molecular Biophysics, Brain Science Institute, RIKEN, Wako, Saitama, Japan.
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Miura M, Matsubara A, Kobayashi T, Edamatsu M, Toyoshima YY. Nucleotide-dependent behavior of single molecules of cytoplasmic dynein on microtubules in vitro. FEBS Lett 2010; 584:2351-5. [PMID: 20394748 DOI: 10.1016/j.febslet.2010.04.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 03/30/2010] [Accepted: 04/07/2010] [Indexed: 11/19/2022]
Abstract
We visualized the nucleotide-dependent behavior of single molecules of mammalian native cytoplasmic dynein using fragments of dynactin p150 with or without its N-terminal microtubule binding domain. The results indicate that the binding affinity of dynein for microtubules is high in AMP-PNP, middle in ADP or no nucleotide, and low in ADP.Pi conditions. It is also demonstrated that the microtubule binding domain of dynactin p150 maintains the association of dynein with microtubules without altering the motile property of dynein in the weak binding state. In addition, we observed bidirectional movement of dynein in the presence of ATP as well as in ADP/Vi condition, suggesting that the bidirectional movement is driven by diffusion rather than active transport.
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Affiliation(s)
- Michi Miura
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan
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14
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Abstract
Microtubule motors drive the movement of many different cargoes in eukaryotic cells. A combination of in vitro and in vivo approaches has led to a better understanding of their mechanism of action and function and are also revealing that the microtubule track itself may have an important role to play in directing cargo movement within the cell.
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Affiliation(s)
- Viki Allan
- Faculty of Life Sciences, University of Manchester The Michael Smith Building, Oxford Road, Manchester M13 9PT UK.
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Regulation of the processivity and intracellular localization of Saccharomyces cerevisiae dynein by dynactin. Proc Natl Acad Sci U S A 2009; 106:5669-74. [PMID: 19293377 DOI: 10.1073/pnas.0900976106] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Dynactin, a large multisubunit complex, is required for intracellular transport by dynein; however, its cellular functions and mechanism of action are not clear. Prior studies suggested that dynactin increases dynein processivity by tethering the motor to the microtubule through its own microtubule binding domains. However, this hypothesis could not be tested without a recombinant source of dynactin. Here, we have produced recombinant dynactin and dynein in Saccharomyces cerevisiae, and examined the effect of dynactin on dynein in single-molecule motility assays. We show that dynactin increases the run length of single dynein motors, but does not alter the directionality of dynein movement. Enhancement of dynein processivity by dynactin does not require the microtubule (MT) binding domains of Nip100 (the yeast p150(Glued) homolog). Dynactin lacking these MT binding domains also supports the proper localization and function of dynein during nuclear segregation in vivo. Instead, a segment of the coiled-coil of Nip100 is required for these activities. Our results directly demonstrate that dynactin increases the processivity of dynein through a mechanism independent of microtubule tethering.
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Zhang N, Liu J, Ding X, Aikhionbare F, Jin C, Yao X. FBXL5 interacts with p150Glued and regulates its ubiquitination. Biochem Biophys Res Commun 2007; 359:34-9. [PMID: 17532294 DOI: 10.1016/j.bbrc.2007.05.068] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Accepted: 05/07/2007] [Indexed: 11/15/2022]
Abstract
The microtubule motor cytoplasmic dynein and its activator dynactin drive vesicular transport and mitotic spindle organization. p150(Glued) is the dynactin subunit responsible for binding to dynein and microtubules. The F-box proteins constitute one of the four subunits of ubiquitin protein ligase complex called SCFs (SKP1-cullin-F-box), which governs phosphorylation-dependent ubiquitination and subsequent proteolysis. Our recent study showed that the proteolysis of mitotic kinesin CENP-E is mediated by SCF via a direct Skp1 link [D. Liu, N. Zhang, J. Du, X. Cai, M. Zhu, C. Jin, Z. Dou, C. Feng, Y. Yang, L. Liu, K. Takeyasu, W. Xie, X. Yao, Interaction of Skp1 with CENP-E at the midbody is essential for cytokinesis, Biochem. Biophys. Res. Commun. 345 (2006) 394-402]. Here we show that F-box protein FBXL5 interacts with p150(Glued) and orchestrates its turnover via ubiquitination. FBXL5 binds to p150(Glued)in vitro and in vivo. FBXL5 and p150(Glued) co-localize primarily in the cytoplasm with peri-nuclear enrichment in HeLa cells. Overexpression of FBXL5 promotes poly-ubiquitination of p150(Glued) and protein turnover of p150(Glued). Our findings provide a potential mechanism by which p150(Glued) protein function is regulated by SCFs.
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Affiliation(s)
- Ning Zhang
- Division of Cellular Dynamics, Hefei National Laboratory for Physical Sciences and Chinese University of Science & Technology, Hefei 230027, China
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17
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Kim H, Ling SC, Rogers GC, Kural C, Selvin PR, Rogers SL, Gelfand VI. Microtubule binding by dynactin is required for microtubule organization but not cargo transport. ACTA ACUST UNITED AC 2007; 176:641-51. [PMID: 17325206 PMCID: PMC2064022 DOI: 10.1083/jcb.200608128] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dynactin links cytoplasmic dynein and other motors to cargo and is involved in organizing radial microtubule arrays. The largest subunit of dynactin, p150glued, binds the dynein intermediate chain and has an N-terminal microtubule-binding domain. To examine the role of microtubule binding by p150glued, we replaced the wild-type p150glued in Drosophila melanogaster S2 cells with mutant ΔN-p150 lacking residues 1–200, which is unable to bind microtubules. Cells treated with cytochalasin D were used for analysis of cargo movement along microtubules. Strikingly, although the movement of both membranous organelles and messenger ribonucleoprotein complexes by dynein and kinesin-1 requires dynactin, the substitution of full-length p150glued with ΔN-p150glued has no effect on the rate, processivity, or step size of transport. However, truncation of the microtubule-binding domain of p150glued has a dramatic effect on cell division, resulting in the generation of multipolar spindles and free microtubule-organizing centers. Thus, dynactin binding to microtubules is required for organizing spindle microtubule arrays but not cargo motility in vivo.
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Affiliation(s)
- Hwajin Kim
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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18
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Ali MY, Krementsova EB, Kennedy GG, Mahaffy R, Pollard TD, Trybus KM, Warshaw DM. Myosin Va maneuvers through actin intersections and diffuses along microtubules. Proc Natl Acad Sci U S A 2007; 104:4332-6. [PMID: 17360524 PMCID: PMC1838602 DOI: 10.1073/pnas.0611471104] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Certain types of intracellular organelle transport to the cell periphery are thought to involve long-range movement on microtubules by kinesin with subsequent handoff to vertebrate myosin Va (myoVa) for local delivery on actin tracks. This process may involve direct interactions between these two processive motors. Here we demonstrate using single molecule in vitro techniques that myoVa is flexible enough to effectively maneuver its way through actin filament intersections and Arp2/3 branches. In addition, myoVa surprisingly undergoes a one-dimensional diffusive search along microtubules, which may allow it to scan efficiently for kinesin and/or its cargo. These features of myoVa may help ensure efficient cargo delivery from the cell center to the periphery.
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Affiliation(s)
- M. Yusuf Ali
- *Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405; and
| | - Elena B. Krementsova
- *Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405; and
| | - Guy G. Kennedy
- *Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405; and
| | - Rachel Mahaffy
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520
| | - Thomas D. Pollard
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520
- To whom correspondence should be addressed. E-mail:
| | - Kathleen M. Trybus
- *Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405; and
| | - David M. Warshaw
- *Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT 05405; and
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Shima T, Imamula K, Kon T, Ohkura R, Sutoh K. Head-head coordination is required for the processive motion of cytoplasmic dynein, an AAA+ molecular motor. J Struct Biol 2006; 156:182-9. [PMID: 16677823 DOI: 10.1016/j.jsb.2006.03.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 03/17/2006] [Accepted: 03/27/2006] [Indexed: 11/21/2022]
Abstract
Cytoplasmic dynein is an AAA(+)-type molecular motor whose major components are two identical heavy chains containing six AAA(+) modules in tandem. It moves along a single microtubule in multiple steps which are accompanied with multiple ATP hydrolysis. This processive sliding is crucial for cargo transports in vivo. To examine how cytoplasmic dynein exhibits this processivity, we performed in vitro motility assays of two-headed full-length or truncated single-headed heavy chains. The results indicated that four to five molecules of the single-headed heavy chain were required for continuous microtubule sliding, while approximately one molecule of the two-headed full-length heavy chain was enough for the continuous sliding. The ratio of the stroking time to the total ATPase cycle time, which is a quantitative indicator of the processivity, was approximately 0.2 for the single-headed heavy chain, while it was approximately 0.6 for the full-length molecule. When two single-headed heavy chains were artificially linked by a coiled-coil of myosin, the processivity was restored. These results suggest that the two heads of a single cytoplasmic dynein communicate with each other to take processive steps along a microtubule.
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Affiliation(s)
- Tomohiro Shima
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo 153-8902, Japan
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