1
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Clark PJ, Brodnik ZD, España RA. Chemogenetic Signaling in Space and Time: Considerations for Designing Neuroscience Experiments Using DREADDs. Neuroscientist 2024; 30:328-346. [PMID: 36408535 DOI: 10.1177/10738584221134587] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
The use of designer receptors exclusively activated by designer drugs (DREADDs) has led to significant advances in our understanding of the neural circuits that govern behavior. By allowing selective control over cellular activity and signaling, DREADDs have become an integral tool for defining the pathways and cellular phenotypes that regulate sleep, pain, motor activity, goal-directed behaviors, and a variety of other processes. In this review, we provide a brief overview of DREADDs and discuss notable discoveries in the neurosciences with an emphasis on circuit mechanisms. We then highlight methodological approaches to achieve pathway specific activation of DREADDs. Finally, we discuss spatial and temporal constraints of DREADDs signaling and how these features can be incorporated into experimental designs to precisely dissect circuits of interest.
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Affiliation(s)
- Philip J Clark
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Zachary D Brodnik
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
| | - Rodrigo A España
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, PA, USA
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2
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Liu W, Gao T, Li N, Shao S, Liu B. Vesicle fusion and release in neurons under dynamic mechanical equilibrium. iScience 2024; 27:109793. [PMID: 38736547 PMCID: PMC11088343 DOI: 10.1016/j.isci.2024.109793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024] Open
Abstract
Vesicular fusion plays a pivotal role in cellular processes, involving stages like vesicle trafficking, fusion pore formation, content release, and membrane integration or separation. This dynamic process is regulated by a complex interplay of protein assemblies, osmotic forces, and membrane tension, which together maintain a mechanical equilibrium within the cell. Changes in cellular mechanics or external pressures prompt adjustments in this equilibrium, highlighting the system's adaptability. This review delves into the synergy between intracellular proteins, structural components, and external forces in facilitating vesicular fusion and release. It also explores how cells respond to mechanical stress, maintaining equilibrium and offering insights into vesicle fusion mechanisms and the development of neurological disorders.
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Affiliation(s)
- Wenhao Liu
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
| | - Tianyu Gao
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
| | - Na Li
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
- Faculty of Medicine, Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
| | - Shuai Shao
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
- Faculty of Medicine, Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
| | - Bo Liu
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
- Faculty of Medicine, Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
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3
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Labastide JA, Quint DA, Cullen RK, Maelfeyt B, Ross JL, Gopinathan A. Non-specific cargo-filament interactions slow down motor-driven transport. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:134. [PMID: 38127202 DOI: 10.1140/epje/s10189-023-00394-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023]
Abstract
Active, motor-based cargo transport is important for many cellular functions and cellular development. However, the cell interior is complex and crowded and could have many weak, non-specific interactions with the cargo being transported. To understand how cargo-environment interactions will affect single motor cargo transport and multi-motor cargo transport, we use an artificial quantum dot cargo bound with few (~ 1) to many (~ 5-10) motors allowed to move in a dense microtubule network. We find that kinesin-driven quantum dot cargo is slower than single kinesin-1 motors. Excitingly, there is some recovery of the speed when multiple motors are attached to the cargo. To determine the possible mechanisms of both the slow down and recovery of speed, we have developed a computational model that explicitly incorporates multi-motor cargos interacting non-specifically with nearby microtubules, including, and predominantly with the microtubule on which the cargo is being transported. Our model has recovered the experimentally measured average cargo speed distribution for cargo-motor configurations with few and many motors, implying that numerous, weak, non-specific interactions can slow down cargo transport and multiple motors can reduce these interactions thereby increasing velocity.
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Affiliation(s)
- Joelle A Labastide
- Department of Physics, University of Massachusetts, 710 North Pleasant Street, Amherst, MA, 01003-9337, USA
| | - David A Quint
- Department of Physics, University of California, Merced, 5200 North Lake Rd, Merced, CA, 95343, USA
- NSF-CREST: Center for Cellular and Biomolecular Machines (CCBM), University of California Merced, Merced, USA
- Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Reilly K Cullen
- Department of Physics, University of Massachusetts, 710 North Pleasant Street, Amherst, MA, 01003-9337, USA
- Division of Basic and Translational Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Bryan Maelfeyt
- Department of Physics, University of California, Merced, 5200 North Lake Rd, Merced, CA, 95343, USA
- NSF-CREST: Center for Cellular and Biomolecular Machines (CCBM), University of California Merced, Merced, USA
| | - Jennifer L Ross
- Department of Physics, University of Massachusetts, 710 North Pleasant Street, Amherst, MA, 01003-9337, USA.
- Department of Physics, Syracuse University, Crouse Drive, Syracuse, NY 13104, USA.
| | - Ajay Gopinathan
- Department of Physics, University of California, Merced, 5200 North Lake Rd, Merced, CA, 95343, USA.
- NSF-CREST: Center for Cellular and Biomolecular Machines (CCBM), University of California Merced, Merced, USA.
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4
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Glomb O, Swaim G, Munoz LLancao P, Lovejoy C, Sutradhar S, Park J, Wu Y, Cason SE, Holzbaur ELF, Hammarlund M, Howard J, Ferguson SM, Gramlich MW, Yogev S. A kinesin-1 adaptor complex controls bimodal slow axonal transport of spectrin in Caenorhabditis elegans. Dev Cell 2023; 58:1847-1863.e12. [PMID: 37751746 PMCID: PMC10574138 DOI: 10.1016/j.devcel.2023.08.031] [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: 06/25/2023] [Revised: 08/18/2023] [Accepted: 08/30/2023] [Indexed: 09/28/2023]
Abstract
An actin-spectrin lattice, the membrane periodic skeleton (MPS), protects axons from breakage. MPS integrity relies on spectrin delivery via slow axonal transport, a process that remains poorly understood. We designed a probe to visualize endogenous spectrin dynamics at single-axon resolution in vivo. Surprisingly, spectrin transport is bimodal, comprising fast runs and movements that are 100-fold slower than previously reported. Modeling and genetic analysis suggest that the two rates are independent, yet both require kinesin-1 and the coiled-coil proteins UNC-76/FEZ1 and UNC-69/SCOC, which we identify as spectrin-kinesin adaptors. Knockdown of either protein led to disrupted spectrin motility and reduced distal MPS, and UNC-76 overexpression instructed excessive transport of spectrin. Artificially linking spectrin to kinesin-1 drove robust motility but inefficient MPS assembly, whereas impairing MPS assembly led to excessive spectrin transport, suggesting a balance between transport and assembly. These results provide insight into slow axonal transport and MPS integrity.
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Affiliation(s)
- Oliver Glomb
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Grace Swaim
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA; Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Pablo Munoz LLancao
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Christopher Lovejoy
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Sabyasachi Sutradhar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA
| | - Junhyun Park
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA
| | - Youjun Wu
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Sydney E Cason
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA; Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA; Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marc Hammarlund
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA; Department of Genetics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA; Quantitative Biology Institute, Yale University, New Haven, CT 06510, USA
| | - Shawn M Ferguson
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | | | - Shaul Yogev
- Department of Neuroscience, Yale School of Medicine, New Haven, CT 06510, USA.
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5
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Straube A. The cell biology of motors. J Cell Sci 2023; 136:297105. [PMID: 36917211 DOI: 10.1242/jcs.261056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023] Open
Affiliation(s)
- Anne Straube
- Warwick Medical School and Centre for Mechanochemical Cell Biology, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, UK
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6
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Karan C, Chaudhuri D. Cooperation and competition in the collective drive by motor proteins: mean active force, fluctuations, and self-load. SOFT MATTER 2023; 19:1834-1843. [PMID: 36789956 DOI: 10.1039/d2sm01183b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We consider the dynamics of a bio-filament under the collective drive of motor proteins. They are attached irreversibly to a substrate and undergo stochastic attachment-detachment with the filament to produce a directed force on it. We establish the dependence of the mean directed force and force correlations on the parameters describing the individual motor proteins using analytical theory and direct numerical simulations. The effective Langevin description for the filament motion gives mean-squared displacement, asymptotic diffusion constant, and mobility leading to an effective temperature. Finally, we show how competition between motor protein extensions generates a self-load, describable in terms of the effective temperature, affecting the filament motion.
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Affiliation(s)
- Chitrak Karan
- Institute of Physics, Sachivalaya Marg, Sainik School, Bhubaneswar, 751005, India.
- Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, India.
| | - Debasish Chaudhuri
- Institute of Physics, Sachivalaya Marg, Sainik School, Bhubaneswar, 751005, India.
- Homi Bhaba National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400094, India.
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7
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Xu A, Basant A, Schleich S, Newsome TP, Way M. Kinesin-1 transports morphologically distinct intracellular virions during vaccinia infection. J Cell Sci 2022; 136:276598. [PMID: 36093836 DOI: 10.1242/jcs.260175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 08/31/2022] [Indexed: 11/20/2022] Open
Abstract
Intracellular mature virus (IMV) are the first and most abundant infectious form of vaccinia virus to assemble during its replication cycle. IMV can undergo microtubule-based motility, but their directionality and the motor involved in their transport remain unknown. Here, we demonstrate that IMV, like intracellular enveloped virus (IEV), the second form of vaccinia that is wrapped in Golgi-derived membrane, recruit kinesin-1 and undergo anterograde transport. In vitro reconstitution of virion transport in infected cell extracts reveals that IMV and IEV move toward microtubule plus-ends with respective velocities of 0.66 and 0.56 µm/s. Quantitative imaging establishes that IMV and IEV recruit an average of 139 and 320 kinesin-1 motor complexes respectively. In the absence of kinesin-1 there is a near-complete loss of in vitro motility and reduction in the intracellular spread of both types of virion. Our observations demonstrate that kinesin-1 transports two morphologically distinct forms of vaccinia. Reconstitution of vaccinia-based microtubule motility in vitro provides a new model to elucidate how motor number and regulation impacts transport of a bona fide kinesin-1 cargo.
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Affiliation(s)
- Amadeus Xu
- Cellular signalling and cytoskeletal function laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Angika Basant
- Cellular signalling and cytoskeletal function laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Sibylle Schleich
- London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK
| | - Timothy P Newsome
- London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK
| | - Michael Way
- Cellular signalling and cytoskeletal function laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London, WC2A 3PX, UK.,Department of Infectious Disease, Imperial College, London W2 1PG, UK
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8
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Humpert I, Di Meo D, Püschel AW, Pietschmann JF. On the role of vesicle transport in neurite growth: Modeling and experiments. Math Biosci 2021; 338:108632. [PMID: 34087317 DOI: 10.1016/j.mbs.2021.108632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/28/2021] [Accepted: 05/17/2021] [Indexed: 10/21/2022]
Abstract
The processes that determine the establishment of the complex morphology of neurons during development are still poorly understood. Here, we focus on the question how a difference in the length of neurites affects vesicle transport. We performed live imaging experiments and present a lattice-based model to gain a deeper theoretical understanding of intracellular transport in neurons. After a motivation and appropriate scaling of the model we present numerical simulations showing that initial differences in neurite length result in phenomena of biological relevance, i.e. a positive feedback that enhances transport into the longer neurite and oscillation of vesicles concentrations that can be interpreted as cycles of extension and retraction observed in experiments. Thus, our model is a first step towards a better understanding of the interplay between the transport of vesicles and the spatial organization of cells.
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Affiliation(s)
- Ina Humpert
- Applied Mathematics Münster: Institute for Analysis and Computational Mathematics, Westfälische Wilhelms-Universität (WWU) Münster, Germany.
| | - Danila Di Meo
- Institute for Molecular Biology, Westfälische-Wilhelms-Universität (WWU) Münster, Germany.
| | - Andreas W Püschel
- Institute for Molecular Biology, Westfälische-Wilhelms-Universität (WWU) Münster, Germany.
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9
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Hayashi K, Miyamoto MG, Niwa S. Effects of dynein inhibitor on the number of motor proteins transporting synaptic cargos. Biophys J 2021; 120:1605-1614. [PMID: 33617835 PMCID: PMC8204214 DOI: 10.1016/j.bpj.2021.02.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 02/02/2021] [Accepted: 02/08/2021] [Indexed: 11/27/2022] Open
Abstract
Synaptic cargo transport by kinesin and dynein in hippocampal neurons was investigated by noninvasively measuring the transport force based on nonequilibrium statistical mechanics. Although direct physical measurements such as force measurement using optical tweezers are difficult in an intracellular environment, the noninvasive estimations enabled enumerating force-producing units (FPUs) carrying a cargo comprising the motor proteins generating force. The number of FPUs served as a barometer for stable and long-distance transport by multiple motors, which was then used to quantify the extent of damage to axonal transport by dynarrestin, a dynein inhibitor. We found that dynarrestin decreased the FPU for retrograde transport more than for anterograde transport. This result indicates the applicability of the noninvasive force measurements. In the future, these measurements may be used to quantify damage to axonal transport resulting from neuronal diseases, including Alzheimer's, Parkinson's, and Huntington's diseases.
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Affiliation(s)
- Kumiko Hayashi
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Japan.
| | - Miki G Miyamoto
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Shinsuke Niwa
- Frontier Research Institute for Interdisciplinary Sciences and Graduate School of Life Science, Tohoku University, Sendai, Japan
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10
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Chemogenetic Manipulation of Dopamine Neurons Dictates Cocaine Potency at Distal Dopamine Transporters. J Neurosci 2020; 40:8767-8779. [PMID: 33046544 DOI: 10.1523/jneurosci.0894-20.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 09/18/2020] [Accepted: 09/27/2020] [Indexed: 12/21/2022] Open
Abstract
The reinforcing efficacy of cocaine is largely determined by its capacity to inhibit the dopamine transporter (DAT), and emerging evidence suggests that differences in cocaine potency are linked to several symptoms of cocaine use disorder. Despite this evidence, the neural processes that govern cocaine potency in vivo remain unclear. In male rats, we used chemogenetics with intra-VTA microinfusions of the agonist clozapine-n-oxide to bidirectionally modulate dopamine neurons. Using ex vivo fast scan cyclic voltammetry, pharmacological probes of the DAT, biochemical assessments of DAT membrane availability and phosphorylation, and cocaine self-administration, we tested the effects of chemogenetic manipulations on cocaine potency at distal DATs in the nucleus accumbens as well as the behavioral economics of cocaine self-administration. We discovered that chemogenetic manipulation of dopamine neurons produced rapid, bidirectional modulation of cocaine potency at DATs in the nucleus accumbens. We then provided evidence that changes in cocaine potency are associated with alterations in DAT affinity for cocaine and demonstrated that this change in affinity coincides with DAT conformation biases and changes in DAT phosphorylation state. Finally, we showed that chemogenetic manipulation of dopamine neurons alters cocaine consumption in a manner consistent with changes in cocaine potency at distal DATs. Based on the spatial and temporal constraints inherent to our experimental design, we posit that changes in cocaine potency are driven by alterations in dopamine neuron activity. When considered together, these observations provide a novel mechanism through which GPCRs regulate cocaine's pharmacological and behavioral effects.SIGNIFICANCE STATEMENT Differences in the pharmacological effects of cocaine are believed to influence the development and progression of cocaine use disorder. However, the biological and physiological processes that determine sensitivity to cocaine remain unclear. In this work, we use a combination of chemogenetics, fast scan cyclic voltammetry, pharmacology, biochemistry, and cocaine self-administration with economic demand analysis to demonstrate a novel mechanism by which cocaine potency is determined in vivo These studies identify a novel process by which the pharmacodynamics of cocaine are derived in vivo, and thus this work has widespread implications for understanding the mechanisms that regulate cocaine consumption across stages of addiction.
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11
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Blackwell R, Jung D, Bukenberger M, Smith AS. The Impact of Rate Formulations on Stochastic Molecular Motor Dynamics. Sci Rep 2019; 9:18373. [PMID: 31804523 PMCID: PMC6895049 DOI: 10.1038/s41598-019-54344-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 11/08/2019] [Indexed: 12/19/2022] Open
Abstract
Cells are complex structures which require considerable amounts of organization via transport of large intracellular cargo. While passive diffusion is often sufficiently fast for the transport of smaller cargo, active transport is necessary to organize large structures on the short timescales necessary for biological function. The main mechanism of this transport is by cargo attachment to motors which walk in a directed fashion along intracellular filaments. There are a number of models which seek to describe the motion of motors with attached cargo, from detailed microscopic to coarse phenomenological descriptions. We focus on the intermediate-detailed discrete stochastic hopping models, and explore how cargo transport changes depending on the number of motors, motor interaction, system constraints and rate formulations, which are derived from common thermodynamic assumptions. We find that, despite obeying the same detailed balance constraint, the choice of rate formulation considerably affects the characteristics of the overall motion of the system, with one rate formulation exhibiting novel behavior of loaded motor groups moving faster than a single unloaded motor.
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Affiliation(s)
- R Blackwell
- PULS group, Physics Department and Interdisciplinary Center for Nanostructured Films, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 3, 91058, Erlangen, Germany
| | - D Jung
- PULS group, Physics Department and Interdisciplinary Center for Nanostructured Films, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 3, 91058, Erlangen, Germany
| | - M Bukenberger
- PULS group, Physics Department and Interdisciplinary Center for Nanostructured Films, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 3, 91058, Erlangen, Germany
| | - A-S Smith
- PULS group, Physics Department and Interdisciplinary Center for Nanostructured Films, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 3, 91058, Erlangen, Germany. .,Group for Computational Life Sciences, Division of Physical Chemistry, Insitut Rūder Bošković, Bijenička cesta 54, 10000, Zagreb, Croatia.
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12
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Wijeratne S, Subramanian R. Geometry of antiparallel microtubule bundles regulates relative sliding and stalling by PRC1 and Kif4A. eLife 2018; 7:32595. [PMID: 30353849 PMCID: PMC6200392 DOI: 10.7554/elife.32595] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 09/28/2018] [Indexed: 12/12/2022] Open
Abstract
Motor and non-motor crosslinking proteins play critical roles in determining the size and stability of microtubule-based architectures. Currently, we have a limited understanding of how geometrical properties of microtubule arrays, in turn, regulate the output of crosslinking proteins. Here we investigate this problem in the context of microtubule sliding by two interacting proteins: the non-motor crosslinker PRC1 and the kinesin Kif4A. The collective activity of PRC1 and Kif4A also results in their accumulation at microtubule plus-ends (‘end-tag’). Sliding stalls when the end-tags on antiparallel microtubules collide, forming a stable overlap. Interestingly, we find that structural properties of the initial array regulate microtubule organization by PRC1-Kif4A. First, sliding velocity scales with initial microtubule-overlap length. Second, the width of the final overlap scales with microtubule lengths. Our analyses reveal how micron-scale geometrical features of antiparallel microtubules can regulate the activity of nanometer-sized proteins to define the structure and mechanics of microtubule-based architectures.
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Affiliation(s)
- Sithara Wijeratne
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General Hospital, Boston, United States.,Department of Genetics, Harvard Medical School, Boston, United States
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13
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Gárate F, Pertusa M, Arana Y, Bernal R. Non-invasive Neurite Mechanics in Differentiated PC12 Cells. Front Cell Neurosci 2018; 12:194. [PMID: 30052690 PMCID: PMC6043779 DOI: 10.3389/fncel.2018.00194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 06/17/2018] [Indexed: 01/04/2023] Open
Abstract
Thermal Fluctuations Spectroscopy (TFS) in combination with novel optical-based instrumentation was used to study mechanical properties of cell-cultured neurites with a spatial resolution limited only by the light diffraction. The analysis of thermal fluctuations together with a physical model of cellular elasticity allow us to determine relevant mechanical properties of neurite as axial tension σ, flexural rigidity B, plasma membrane tension γ, membrane bending rigidity K, and cytoskeleton to membrane-coupling ρbk, whose values are consistent with previously reported values measured using invasive approaches. The value obtained for the membrane-coupling parameter was used to estimate the average number of coupling elements between the plasma membrane and the cytoskeleton that fell in the range of 30 elements per area of the laser spot used to record the fluctuations. Furthermore, to expand the TFS analysis, we investigate the correlation between F-actin linear density and the mechanical features of PC12 neurites. Using a hybrid instrument that combines TFS and a simple fluorescent technique, our results show that the fluctuations are related with the F-actin concentration. These measurements have an advantage of not requiring the application of an external force, allowing as to directly establish a correlation between changes in the mechanical parameters and cytoskeleton-protein concentrations. The sensibility of our method was also tested by the application of TFS technique to PC12 neurite under Paraformaldehyde and Latrunculin-A effect. These results show a dramatic modification in the fluctuations that are consistent with the reported effect of these drugs, confirming the high sensitivity of this technique. Finally, the thermal fluctuation approach was applied to DRG axons to show that its utility is not limited to studies of PC12 neurites, but it is suitable to measure the general characteristic of various neuron-like cells.
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Affiliation(s)
- Fernanda Gárate
- Cellular Mechanics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile.,Biophysics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile
| | - María Pertusa
- Department of Biology, Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), University of Santiago de Chile, Santiago, Chile
| | - Yahaira Arana
- Cellular Mechanics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile
| | - Roberto Bernal
- Cellular Mechanics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile
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14
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Abstract
Kinesin is a molecular motor that transports cargo along microtubules. The results of many in vitro experiments on kinesin-1 are described by kinetic models in which one transition corresponds to the forward motion and subsequent binding of the tethered motor head. We argue that in a viscoelastic medium like the cytosol of a cell this step is not Markov and has to be described by a nonexponential waiting time distribution. We introduce a semi-Markov kinetic model for kinesin that takes this effect into account. We calculate, for arbitrary waiting time distributions, the moment generating function of the number of steps made, and determine from this the average velocity and the diffusion constant of the motor. We illustrate our results for the case of a waiting time distribution that is Weibull. We find that for realistic parameter values, viscoelasticity decreases the velocity and the diffusion constant, but increases the randomness (or Fano factor).
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Affiliation(s)
- Gert Knoops
- Faculty of Sciences, Hasselt University, 3590 Diepenbeek, Belgium
| | - Carlo Vanderzande
- Faculty of Sciences, Hasselt University, 3590 Diepenbeek, Belgium
- Instituut Theoretische Fysica, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium
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15
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Bencsik A, Lestaevel P, Guseva Canu I. Nano- and neurotoxicology: An emerging discipline. Prog Neurobiol 2018; 160:45-63. [DOI: 10.1016/j.pneurobio.2017.10.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 09/10/2017] [Accepted: 10/20/2017] [Indexed: 12/12/2022]
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16
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Becher A, Eiseler T, Porzner M, Walther P, Keil R, Bobrovich S, Hatzfeld M, Seufferlein T. The armadillo protein p0071 controls KIF3 motor transport. J Cell Sci 2017; 130:3374-3387. [PMID: 28808088 DOI: 10.1242/jcs.200170] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 08/02/2017] [Indexed: 01/17/2023] Open
Abstract
We here report a novel function of the armadillo protein p0071 (also known as PKP4) during transport mediated by the KIF3 transport complex. Secretion of chromogranin A and matrix metallopeptidase 9 from pancreatic neuroendocrine tumor cells or pancreatic cancer cells, respectively, was substantially reduced following knockdown of p0071. Vesicle tracking indicated that there was impaired directional persistence of vesicle movement upon p0071 depletion. This suggests a disturbed balance between plus- and minus-end directed microtubule transport in cells lacking p0071. p0071 directly interacts with the KIF3 motor subunit KIF3B. Our data indicate that p0071 also interacts with the kinesin cargo adaptor protein KAP3 (also known as KIFAP3) acting as a stabilizing linker between KIF3B and its KAP3 cargo-binding entity. Thus, p0071 is required for directional vesicle movement and secretion of different KIF3-transported carriers, thereby regulating the transport of intracellular membrane vesicles along microtubules.
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Affiliation(s)
- Alexander Becher
- Department of Internal Medicine I, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Tim Eiseler
- Department of Internal Medicine I, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Marc Porzner
- Department of Internal Medicine I, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - René Keil
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University of Halle-Wittenberg, D-06114 Halle, Germany
| | - Susanne Bobrovich
- Department of Internal Medicine I, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Mechthild Hatzfeld
- Institute of Molecular Medicine, Division of Pathobiochemistry, Martin-Luther-University of Halle-Wittenberg, D-06114 Halle, Germany
| | - Thomas Seufferlein
- Department of Internal Medicine I, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany
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17
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Ross JL. The Dark Matter of Biology. Biophys J 2017; 111:909-16. [PMID: 27602719 PMCID: PMC5018137 DOI: 10.1016/j.bpj.2016.07.037] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 07/06/2016] [Accepted: 07/26/2016] [Indexed: 02/04/2023] Open
Abstract
The inside of the cell is full of important, yet invisible species of molecules and proteins that interact weakly but couple together to have huge and important effects in many biological processes. Such “dark matter” inside cells remains mostly hidden, because our tools were developed to investigate strongly interacting species and folded proteins. Example dark-matter species include intrinsically disordered proteins, posttranslational states, ion species, and rare, transient, and weak interactions undetectable by biochemical assays. The dark matter of biology is likely to have multiple, vital roles to regulate signaling, rates of reactions, water structure and viscosity, crowding, and other cellular activities. We need to create new tools to image, detect, and understand these dark-matter species if we are to truly understand fundamental physical principles of biology.
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Affiliation(s)
- Jennifer L Ross
- Department of Physics, University of Massachusetts Amherst, Amherst, Massachusetts.
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18
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Krementsova EB, Furuta K, Oiwa K, Trybus KM, Ali MY. Small teams of myosin Vc motors coordinate their stepping for efficient cargo transport on actin bundles. J Biol Chem 2017; 292:10998-11008. [PMID: 28476885 DOI: 10.1074/jbc.m117.780791] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 05/03/2017] [Indexed: 11/06/2022] Open
Abstract
Myosin Vc (myoVc) is unique among vertebrate class V myosin isoforms in that it requires teams of motors to move continuously on single actin filaments. Single molecules of myoVc cannot take multiple hand-over-hand steps from one actin-binding site to the next without dissociating, in stark contrast to the well studied myosin Va (myoVa) isoform. At low salt, single myoVc motors can, however, move processively on actin bundles, and at physiologic ionic strength, even teams of myoVc motors require actin bundles to sustain continuous motion. Here, we linked defined numbers of myoVc or myoVa molecules to DNA nanostructures as synthetic cargos. Using total internal reflectance fluorescence microscopy, we compared the stepping behavior of myoVc versus myoVa ensembles and myoVc stepping patterns on single actin filaments versus actin bundles. Run lengths of both myoVc and myoVa teams increased with motor number, but only multiple myoVc motors showed a run-length enhancement on actin bundles compared with actin filaments. By resolving the stepping behavior of individual myoVc motors with a quantum dot bound to the motor domain, we found that coupling of two myoVc motors significantly decreased the futile back and side steps that were frequently observed for single myoVc motors. Changes in the inter-motor distance between two coupled myoVc motors affected stepping dynamics, suggesting that mechanical tension coordinates the stepping behavior of two myoVc motors for efficient directional motion. Our study provides a molecular basis to explain how teams of myoVc motors are suited to transport cargos such as zymogen granules on actin bundles.
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Affiliation(s)
- Elena B Krementsova
- From the Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405 and
| | - Ken'ya Furuta
- the Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Kazuhiro Oiwa
- the Advanced ICT Research Institute, National Institute of Information and Communications Technology, Kobe 651-2492, Japan
| | - Kathleen M Trybus
- From the Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405 and
| | - M Yusuf Ali
- From the Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont 05405 and
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19
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Vandebroek H, Vanderzande C. The effect of active fluctuations on the dynamics of particles, motors and DNA-hairpins. SOFT MATTER 2017; 13:2181-2191. [PMID: 28239703 DOI: 10.1039/c6sm02568d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Inspired by recent experiments on the dynamics of particles and polymers in artificial cytoskeletons and in cells, we introduce a modified Langevin equation for a particle in an environment that is a viscoelastic medium and that is brought out of equilibrium by the action of active fluctuations caused by molecular motors. We show that within such a model, the motion of a free particle crosses over from superdiffusive to subdiffusive as observed for tracer particles in an in vitro cytoskeleton or in a cell. We investigate the dynamics of a particle confined by a harmonic potential as a simple model for the motion of the tethered head of kinesin-1. We find that the probability that the head is close to its binding site on the microtubule can be enhanced by a factor of two due to active forces. Finally, we study the dynamics of a particle in a double well potential as a model for the dynamics of DNA-hairpins. We show that the active forces effectively lower the potential barrier between the two minima and study the impact of this phenomenon on the zipping/unzipping rate.
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Affiliation(s)
- Hans Vandebroek
- Faculty of Sciences, Hasselt University, 3590 Diepenbeek, Belgium.
| | - Carlo Vanderzande
- Faculty of Sciences, Hasselt University, 3590 Diepenbeek, Belgium. and Instituut Theoretische Fysica, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium
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20
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ER-endosome contact sites in endosome positioning and protrusion outgrowth. Biochem Soc Trans 2016; 44:441-6. [PMID: 27068952 DOI: 10.1042/bst20150246] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Indexed: 01/09/2023]
Abstract
The endoplasmic reticulum (ER) makes abundant contacts with endosomes, and the numbers of contact sites increase as endosomes mature. It is already clear that such contact sites have diverse compositions and functions, but in this mini-review we will focus on two particular types of ER-endosome contact sites that regulate endosome positioning. Formation of ER-endosome contact sites that contain the cholesterol-binding protein oxysterol-binding protein-related protein 1L (ORP1L) is coordinated with loss of the minus-end-directed microtubule motor Dynein from endosomes. Conversely, formation of ER-endosome contact sites that contain the Kinesin-1-binding protein Protrudin results in transfer of the plus-end-directed microtubule motor Kinesin-1 from ER to endosomes. We discuss the possibility that formation of these two types of contact sites is coordinated as a 'gear-shift' mechanism for endosome motility, and we review evidence that Kinesin-1-mediated motility of late endosomes (LEs) to the cell periphery promotes outgrowth of neurites and other protrusions.
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21
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Chaphalkar AR, Jain K, Gangan MS, Athale CA. Automated Multi-Peak Tracking Kymography (AMTraK): A Tool to Quantify Sub-Cellular Dynamics with Sub-Pixel Accuracy. PLoS One 2016; 11:e0167620. [PMID: 27992448 PMCID: PMC5167257 DOI: 10.1371/journal.pone.0167620] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 11/17/2016] [Indexed: 11/18/2022] Open
Abstract
Kymographs or space-time plots are widely used in cell biology to reduce the dimensions of a time-series in microscopy for both qualitative and quantitative insight into spatio-temporal dynamics. While multiple tools for image kymography have been described before, quantification remains largely manual. Here, we describe a novel software tool for automated multi-peak tracking kymography (AMTraK), which uses peak information and distance minimization to track and automatically quantify kymographs, integrated in a GUI. The program takes fluorescence time-series data as an input and tracks contours in the kymographs based on intensity and gradient peaks. By integrating a branch-point detection method, it can be used to identify merging and splitting events of tracks, important in separation and coalescence events. In tests with synthetic images, we demonstrate sub-pixel positional accuracy of the program. We test the program by quantifying sub-cellular dynamics in rod-shaped bacteria, microtubule (MT) transport and vesicle dynamics. A time-series of E. coli cell division with labeled nucleoid DNA is used to identify the time-point and rate at which the nucleoid segregates. The mean velocity of microtubule (MT) gliding motility due to a recombinant kinesin motor is estimated as 0.5 μm/s, in agreement with published values, and comparable to estimates using software for nanometer precision filament-tracking. We proceed to employ AMTraK to analyze previously published time-series microscopy data where kymographs had been manually quantified: clathrin polymerization kinetics during vesicle formation and anterograde and retrograde transport in axons. AMTraK analysis not only reproduces the reported parameters, it also provides an objective and automated method for reproducible analysis of kymographs from in vitro and in vivo fluorescence microscopy time-series of sub-cellular dynamics.
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22
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Lopes CDF, Gomes CP, Neto E, Sampaio P, Aguiar P, Pêgo AP. Microfluidic-based platform to mimic the in vivo peripheral administration of neurotropic nanoparticles. Nanomedicine (Lond) 2016; 11:3205-3221. [DOI: 10.2217/nnm-2016-0247] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Aim: Propose a nanoparticle for neuron-targeted retrograde gene delivery and describe a microfluidic-based culture system to provide insight into vector performance and safety. Methods: Using compartmentalized neuron cultures we dissected nanoparticle bioactivity upon delivery taking advantage of (quantitative) bioimaging tools. Results: Targeted and nontargeted nanoparticles were internalized at axon terminals and retrogradely transported to cell bodies at similar average velocities but the former have shown an axonal flux 2.7-times superior to nontargeted nanoparticles, suggesting an improved cargo-transportation efficiency. The peripheral administration of nanoparticles to axon terminals is nontoxic as compared with their direct administration to the cell body or whole neuron. Conclusion: A neuron-targeted nanoparticle system was put forward. Microfluidic-based neuron cultures are proposed as a powerful tool to investigate nanoparticle bio-performance.
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Affiliation(s)
- Cátia DF Lopes
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- Faculdade de Medicina da Universidade do Porto, Alameda Prof Hernâni Monteiro, 4200-319 Porto, Portugal
| | - Carla P Gomes
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- Faculdade de Engenharia da Universidade do Porto, Rua Dr Roberto Frias, s/n 4200-465 Porto, Portugal
| | - Estrela Neto
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- Faculdade de Medicina da Universidade do Porto, Alameda Prof Hernâni Monteiro, 4200-319 Porto, Portugal
| | - Paula Sampaio
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Paulo Aguiar
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Ana P Pêgo
- INEB – Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
- Faculdade de Engenharia da Universidade do Porto, Rua Dr Roberto Frias, s/n 4200-465 Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
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23
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Bhaban S, Materassi D, Li M, Hays T, Salapaka M. Interrogating Emergent Transport Properties for Molecular Motor Ensembles: A Semi-analytical Approach. PLoS Comput Biol 2016; 12:e1005152. [PMID: 27812098 PMCID: PMC5094777 DOI: 10.1371/journal.pcbi.1005152] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 09/17/2016] [Indexed: 11/18/2022] Open
Abstract
Intracellular transport is an essential function in eucaryotic cells, facilitated by motor proteins—proteins converting chemical energy into kinetic energy. It is understood that motor proteins work in teams enabling unidirectional and bidirectional transport of intracellular cargo over long distances. Disruptions of the underlying transport mechanisms, often caused by mutations that alter single motor characteristics, are known to cause neurodegenerative diseases. For example, phosphorylation of kinesin motor domain at the serine residue is implicated in Huntington’s disease, with a recent study of phosphorylated and phosphomimetic serine residues indicating lowered single motor stalling forces. In this article we report the effects of mutations of this nature on transport properties of cargo carried by multiple wild-type and mutant motors. Results indicate that mutants with altered stall forces might determine the average velocity and run-length even when they are outnumbered by wild type motors in the ensemble. It is shown that mutants gain a competitive advantage and lead to an increase in the expected run-length when the load on the cargo is in the vicinity of the mutant’s stalling force or a multiple of its stalling force. A separate contribution of this article is the development of a semi-analytic method to analyze transport of cargo by multiple motors of multiple types. The technique determines transition rates between various relative configurations of motors carrying the cargo using the transition rates between various absolute configurations. This enables a computation of biologically relevant quantities like average velocity and run-length without resorting to Monte Carlo simulations. It can also be used to introduce alterations of various single motor parameters to model a mutation and to deduce effects of such alterations on the transport of a common cargo by multiple motors. Our method is easily implementable and we provide a software package for general use. Molecular motors such as kinesin and dynein facilitate directed transport of intracellular cargo over tracks called microtubules. Inside cells, multiple motor proteins are known to bind and move cargoes. These teams of motors enable the transport of cargoes over longer distances, extending beyond the processive runlengths of a single motor. Impaired transport, possibly due to mutations that affect single motor parameters, is known to cause neurodegenerative diseases. A recent study reported that phosphorylation of a kinesin motor implicated in Huntington’s disease, leads to a reduction in the single motor stalling force. In this work, we investigate how heterogeneity in motor stall forces can affect the coordinated transport properties of multi-motor ensembles. Our model predicts that motors with reduced stall force, even when in the minority, can determine emergent transport properties of average velocity and run-length. Under appropriate external loads, our analysis predicts that motor ensembles containing mutant motors travel longer distances, potentially contributing to the dysregulation of coordinated cargo transport, impairment of neuronal function and the onset of neurodegeneration. These results are enabled by development of a novel semi-analytic methodology to study cargo transport by multiple motors with distinct transport properties. This method is computationally less extensive than existing Monte-Carlo based approaches, easy to implement, and holds potential for understanding how individual motor proteins and properties contribute to the coordination of transport by motor ensembles.
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Affiliation(s)
- Shreyas Bhaban
- Department of Electrical Engineering, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
| | - Donatello Materassi
- Department of Electrical Engineering and Computer Science, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America
| | - Mingang Li
- Department of Genetics, Cell Biology, and Development, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
| | - Thomas Hays
- Department of Genetics, Cell Biology, and Development, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
| | - Murti Salapaka
- Department of Electrical Engineering, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
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24
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Transport efficiency of membrane-anchored kinesin-1 motors depends on motor density and diffusivity. Proc Natl Acad Sci U S A 2016; 113:E7185-E7193. [PMID: 27803325 DOI: 10.1073/pnas.1611398113] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
In eukaryotic cells, membranous vesicles and organelles are transported by ensembles of motor proteins. These motors, such as kinesin-1, have been well characterized in vitro as single molecules or as ensembles rigidly attached to nonbiological substrates. However, the collective transport by membrane-anchored motors, that is, motors attached to a fluid lipid bilayer, is poorly understood. Here, we investigate the influence of motors' anchorage to a lipid bilayer on the collective transport characteristics. We reconstituted "membrane-anchored" gliding motility assays using truncated kinesin-1 motors with a streptavidin-binding peptide tag that can attach to streptavidin-loaded, supported lipid bilayers. We found that the diffusing kinesin-1 motors propelled the microtubules in the presence of ATP. Notably, we found the gliding velocity of the microtubules to be strongly dependent on the number of motors and their diffusivity in the lipid bilayer. The microtubule gliding velocity increased with increasing motor density and membrane viscosity, reaching up to the stepping velocity of single motors. This finding is in contrast to conventional gliding motility assays where the density of surface-immobilized kinesin-1 motors does not influence the microtubule velocity over a wide range. We reason that the transport efficiency of membrane-anchored motors is reduced because of their slippage in the lipid bilayer, an effect that we directly observed using single-molecule fluorescence microscopy. Our results illustrate the importance of motor-cargo coupling, which potentially provides cells with an additional means of regulating the efficiency of cargo transport.
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25
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Geitmann A, Nebenführ A. Navigating the plant cell: intracellular transport logistics in the green kingdom. Mol Biol Cell 2016; 26:3373-8. [PMID: 26416952 PMCID: PMC4591683 DOI: 10.1091/mbc.e14-10-1482] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Intracellular transport in plant cells occurs on microtubular and actin arrays. Cytoplasmic streaming, the rapid motion of plant cell organelles, is mostly driven by an actin–myosin mechanism, whereas specialized functions, such as the transport of large cargo or the assembly of a new cell wall during cell division, are performed by the microtubules. Different modes of transport are used, fast and slow, to either haul cargo over long distances or ascertain high-precision targeting, respectively. Various forms of the actin-specific motor protein myosin XI exist in plant cells and might be involved in different cellular functions.
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Affiliation(s)
- Anja Geitmann
- Department of Biological Sciences, Institut de recherche en biologie végétale, University of Montreal, Montreal, QC H1X 2B2, Canada
| | - Andreas Nebenführ
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996-0840
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26
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Gárate F, Betz T, Pertusa M, Bernal R. Time-resolved neurite mechanics by thermal fluctuation assessments. Phys Biol 2015; 12:066020. [PMID: 26717293 DOI: 10.1088/1478-3975/12/6/066020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In the absence of simple noninvasive measurements, the knowledge of temporal and spatial variations of axons mechanics remains scarce. By extending thermal fluctuation spectroscopy (TFS) to long protrusions, we determine the transverse amplitude thermal fluctuation spectra that allow direct and simultaneous access to three key mechanics parameters: axial tension, bending flexural rigidity and plasma membrane tension. To test our model, we use PC12 cell protrusions-a well-know biophysical model of axons-in order to simplify the biological system under scope. For instance, axial and plasma membrane tension are found in the range of nano Newton and tens of pico Newtons per micron respectively. Furthermore, our results shows that the TFS technique is capable to distinguish quasi-identical protrusions. Another advantage of our approach is the time resolved nature of the measurements. Indeed, in the case of long term experiments on PC12 protrusions, TFS has revealed large temporal, correlated variations of the protrusion mechanics, displaying extraordinary feedback control over the axial tension in order to maintain a constant tension value.
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Affiliation(s)
- Fernanda Gárate
- Departamento de Física and SMAT-C, Universidad de Santiago de Chile, 9170124 Santiago, Chile
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27
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Chowdary PD, Che DL, Kaplan L, Chen O, Pu K, Bawendi M, Cui B. Nanoparticle-assisted optical tethering of endosomes reveals the cooperative function of dyneins in retrograde axonal transport. Sci Rep 2015; 5:18059. [PMID: 26656461 PMCID: PMC4674899 DOI: 10.1038/srep18059] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 10/27/2015] [Indexed: 01/01/2023] Open
Abstract
Dynein-dependent transport of organelles from the axon terminals to the cell bodies is essential to the survival and function of neurons. However, quantitative knowledge of dyneins on axonal organelles and their collective function during this long-distance transport is lacking because current technologies to do such measurements are not applicable to neurons. Here, we report a new method termed nanoparticle-assisted optical tethering of endosomes (NOTE) that made it possible to study the cooperative mechanics of dyneins on retrograde axonal endosomes in live neurons. In this method, the opposing force from an elastic tether causes the endosomes to gradually stall under load and detach with a recoil velocity proportional to the dynein forces. These recoil velocities reveal that the axonal endosomes, despite their small size, can recruit up to 7 dyneins that function as independent mechanical units stochastically sharing load, which is vital for robust retrograde axonal transport. This study shows that NOTE, which relies on controlled generation of reactive oxygen species, is a viable method to manipulate small cellular cargos that are beyond the reach of current technology.
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Affiliation(s)
- Praveen D. Chowdary
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, CA 94305, USA
| | - Daphne L. Che
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, CA 94305, USA
| | - Luke Kaplan
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, CA 94305, USA
| | - Ou Chen
- Department of Chemistry, Massachussets Institute of Technology, 77 Massachussets Ave, Cambridge, MA 02139, USA
| | - Kanyi Pu
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, N1.3, B2-05, Singapore 637459
| | - Moungi Bawendi
- Department of Chemistry, Massachussets Institute of Technology, 77 Massachussets Ave, Cambridge, MA 02139, USA
| | - Bianxiao Cui
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, CA 94305, USA
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28
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Martin MJ, Smelser AM, Holzwarth G. Dividing organelle tracks into Brownian and motor-driven intervals by variational maximization of the Bayesian evidence. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 45:269-77. [PMID: 26538332 DOI: 10.1007/s00249-015-1091-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 10/06/2015] [Accepted: 10/13/2015] [Indexed: 11/26/2022]
Abstract
Many organelles and vesicles in live cells move in a start-stop manner when observed for ~10 s by optical microscopy. Changes in velocity and directional persistence of such particles are a potentially rich source of insight into the mechanisms leading to the start and stop states. Unbiased assessment of the most probable number of states, the properties of each state, and the most probable state for the particle at each moment can be accomplished by variational Bayesian methods combined with a hidden Markov model and a Gaussian mixture model. Our track analysis method, "vbTRACK", applied this combination of methods to particle velocity v or changes in the direction of travel evaluated from simulated tracks and from tracks of peroxisomes in live cells. When tested with numerical data, vbTRACK reliably determined the number of states, the mean and variance of the velocity or the direction of travel for each state, and the most probable state during each frame. When applied to the tracks of peroxisomes in live cells, some tracks separated into two states, one with high velocity and directionality, the other approximately Brownian. Other tracks of particles in live cells separated into several diffusive states with distinct diffusion constants.
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Affiliation(s)
- Matthew J Martin
- Department of Physics, Wake Forest University, Winston-Salem, NC, USA
| | - Amanda M Smelser
- Department of Physics, Wake Forest University, Winston-Salem, NC, USA
- Department of Biochemistry, School of Medicine, Wake Forest University, Winston-Salem, NC, USA
| | - George Holzwarth
- Department of Physics, Wake Forest University, Winston-Salem, NC, USA.
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29
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De Rossi MC, De Rossi ME, Sued M, Rodríguez D, Bruno L, Levi V. Asymmetries in kinesin-2 and cytoplasmic dynein contributions to melanosome transport. FEBS Lett 2015; 589:2763-8. [DOI: 10.1016/j.febslet.2015.07.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/17/2015] [Accepted: 07/20/2015] [Indexed: 10/23/2022]
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30
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Nam W, Epureanu BI. Highly loaded behavior of kinesins increases the robustness of transport under high resisting loads. PLoS Comput Biol 2015; 11:e1003981. [PMID: 25734978 PMCID: PMC4347983 DOI: 10.1371/journal.pcbi.1003981] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 10/11/2014] [Indexed: 11/19/2022] Open
Abstract
Kinesins are nano-sized biological motors which walk by repeating a mechanochemical cycle. A single kinesin molecule is able to transport its cargo about 1 μm in the absence of external loads. However, kinesins perform much longer range transport in cells by working collectively. This long range of transport by a team of kinesins is surprising because the motion of the cargo in cells can be hindered by other particles. To reveal how the kinesins are able to accomplish their tasks of transport in harsh intracellular circumstances, stochastic studies on the kinesin motion are performed by considering the binding and unbinding of kinesins to microtubules and their dependence on the force acting on kinesin molecules. The unbinding probabilities corresponding to each mechanochemical state of kinesin are modeled. The statistical characterization of the instants and locations of binding are captured by computing the probability of unbound kinesin being at given locations. It is predicted that a group of kinesins has a more efficient transport than a single kinesin from the perspective of velocity and run length. Particularly, when large loads are applied, the leading kinesin remains bound to the microtubule for long time which increases the chances of the other kinesins to bind to the microtubule. To predict effects of this behavior of the leading kinesin under large loads on the collective transport, the motion of the cargo is studied when the cargo confronts obstacles. The result suggests that the behavior of kinesins under large loads prevents the early termination of the transport which can be caused by the interference with the static or moving obstacles.
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Affiliation(s)
- Woochul Nam
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bogdan I. Epureanu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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31
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Mussel M, Zeevy K, Diamant H, Nevo U. Drag of the cytosol as a transport mechanism in neurons. Biophys J 2015; 106:2710-9. [PMID: 24940788 DOI: 10.1016/j.bpj.2014.04.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/26/2014] [Accepted: 04/28/2014] [Indexed: 01/15/2023] Open
Abstract
Axonal transport is typically divided into two components, which can be distinguished by their mean velocity. The fast component includes steady trafficking of different organelles and vesicles actively transported by motor proteins. The slow component comprises nonmembranous materials that undergo infrequent bidirectional motion. The underlying mechanism of slow axonal transport has been under debate during the past three decades. We propose a simple displacement mechanism that may be central for the distribution of molecules not carried by vesicles. It relies on the cytoplasmic drag induced by organelle movement and readily accounts for key experimental observations pertaining to slow-component transport. The induced cytoplasmic drag is predicted to depend mainly on the distribution of microtubules in the axon and the organelle transport rate.
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Affiliation(s)
- Matan Mussel
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Keren Zeevy
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Haim Diamant
- School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| | - Uri Nevo
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
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Wortman JC, Shrestha UM, Barry DM, Garcia ML, Gross SP, Yu CC. Axonal transport: how high microtubule density can compensate for boundary effects in small-caliber axons. Biophys J 2014; 106:813-23. [PMID: 24559984 DOI: 10.1016/j.bpj.2013.12.047] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 12/27/2013] [Accepted: 12/31/2013] [Indexed: 01/12/2023] Open
Abstract
Long-distance intracellular axonal transport is predominantly microtubule-based, and its impairment is linked to neurodegeneration. In this study, we present theoretical arguments that suggest that near the axon boundaries (walls), the effective viscosity can become large enough to impede cargo transport in small (but not large) caliber axons. Our theoretical analysis suggests that this opposition to motion increases rapidly as the cargo approaches the wall. We find that having parallel microtubules close enough together to enable a cargo to simultaneously engage motors on more than one microtubule dramatically enhances motor activity, and thus minimizes the effects of any opposition to transport. Even if microtubules are randomly placed in axons, we find that the higher density of microtubules found in small-caliber axons increases the probability of having parallel microtubules close enough that they can be used simultaneously by motors on a cargo. The boundary effect is not a factor in transport in large-caliber axons where the microtubule density is lower.
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Affiliation(s)
- Juliana C Wortman
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697
| | - Uttam M Shrestha
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697
| | - Devin M Barry
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110
| | | | - Steven P Gross
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697; Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697
| | - Clare C Yu
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA 92697.
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Motor coupling through lipid membranes enhances transport velocities for ensembles of myosin Va. Proc Natl Acad Sci U S A 2014; 111:E3986-95. [PMID: 25201964 DOI: 10.1073/pnas.1406535111] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Myosin Va is an actin-based molecular motor responsible for transport and positioning of a wide array of intracellular cargoes. Although myosin Va motors have been well characterized at the single-molecule level, physiological transport is carried out by ensembles of motors. Studies that explore the behavior of ensembles of molecular motors have used nonphysiological cargoes such as DNA linkers or glass beads, which do not reproduce one key aspect of vesicular systems--the fluid intermotor coupling of biological lipid membranes. Using a system of defined synthetic lipid vesicles (100- to 650-nm diameter) composed of either 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) (fluid at room temperature) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (gel at room temperature) with a range of surface densities of myosin Va motors (32-125 motors per μm(2)), we demonstrate that the velocity of vesicle transport by ensembles of myosin Va is sensitive to properties of the cargo. Gel-state DPPC vesicles bound with multiple motors travel at velocities equal to or less than vesicles with a single myosin Va (∼450 nm/s), whereas surprisingly, ensembles of myosin Va are able to transport fluid-state DOPC vesicles at velocities significantly faster (>700 nm/s) than a single motor. To explain these data, we developed a Monte Carlo simulation that suggests that these reductions in velocity can be attributed to two distinct mechanisms of intermotor interference (i.e., load-dependent modulation of stepping kinetics and binding-site exclusion), whereas faster transport velocities are consistent with a model wherein the normal stepping behavior of the myosin is supplemented by the preferential detachment of the trailing motor from the actin track.
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Abstract
Lysosomes are membrane-bound organelles responsible for the transport and degradation of intracellular and extracellular cargo. The intracellular motion of lysosomes is both diffusive and active, mediated by motor proteins moving lysosomes along microtubules. We sought to determine how lysosome diameter influences lysosome transport. We used osmotic swelling to double the diameter of lysosomes, creating a population of enlarged lysosomes. This allowed us to directly examine the intracellular transport of the same organelle as a function of diameter. Lysosome transport was measured using live cell fluorescence microscopy and single particle tracking. We find, as expected, the diffusive component of intracellular transport is decreased proportional to the increased lysosome diameter. Active transport of the enlarged lysosomes is not affected by the increased lysosome diameter.
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Abstract
Characterizing the collective functions of cytoskeletal motors is critical to understanding mechanisms that regulate the internal organization of eukaryotic cells as well as the roles various transport defects play in human diseases. Though in vitro assays using synthetic motor complexes have generated important insights, dissecting collective motor functions within living cells still remains challenging. Here, we show that the protein heterodimerization switches FKBP-rapalog-FRB can be harnessed in engineered COS-7 cells to compare the collective responses of kinesin-1 and myosinVa motors to changes in motor number and cargo size. The dependence of cargo velocities, travel distances, and position noise on these parameters suggests that multiple myosinVa motors can cooperate more productively than collections of kinesins in COS-7 cells. In contrast to observations with kinesin-1 motors, the velocities and run lengths of peroxisomes driven by multiple myosinVa motors are found to increase with increasing motor density, but are relatively insensitive to the higher loads associated with transporting large peroxisomes in the viscoelastic environment of the COS-7 cell cytoplasm. Moreover, these distinctions appear to be derived from the different sensitivities of kinesin-1 and myosinVa velocities and detachment rates to forces at the single-motor level. The collective behaviors of certain processive motors, like myosinVa, may therefore be more readily tunable and have more substantial roles in intracellular transport regulatory mechanisms compared with those of other cytoskeletal motors.
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Materassi D, Roychowdhury S, Hays T, Salapaka M. An exact approach for studying cargo transport by an ensemble of molecular motors. BMC BIOPHYSICS 2013; 6:14. [PMID: 24237658 PMCID: PMC3879128 DOI: 10.1186/2046-1682-6-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 10/22/2013] [Indexed: 11/24/2022]
Abstract
Background Intracellular transport is crucial for many cellular processes where a large fraction of the cargo is transferred by motor-proteins over a network of microtubules. Malfunctions in the transport mechanism underlie a number of medical maladies. Existing methods for studying how motor-proteins coordinate the transfer of a shared cargo over a microtubule are either analytical or are based on Monte-Carlo simulations. Approaches that yield analytical results, while providing unique insights into transport mechanism, make simplifying assumptions, where a detailed characterization of important transport modalities is difficult to reach. On the other hand, Monte-Carlo based simulations can incorporate detailed characteristics of the transport mechanism; however, the quality of the results depend on the number and quality of simulation runs used in arriving at results. Here, for example, it is difficult to simulate and study rare-events that can trigger abnormalities in transport. Results In this article, a semi-analytical methodology that determines the probability distribution function of motor-protein behavior in an exact manner is developed. The method utilizes a finite-dimensional projection of the underlying infinite-dimensional Markov model, which retains the Markov property, and enables the detailed and exact determination of motor configurations, from which meaningful inferences on transport characteristics of the original model can be derived. Conclusions Under this novel probabilistic approach new insights about the mechanisms of action of these proteins are found, suggesting hypothesis about their behavior and driving the design and realization of new experiments. The advantages provided in accuracy and efficiency make it possible to detect rare events in the motor protein dynamics, that could otherwise pass undetected using standard simulation methods. In this respect, the model has allowed to provide a possible explanation for possible mechanisms under which motor proteins could coordinate their motion.
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Affiliation(s)
- Donatello Materassi
- Laboratory for Information and Decision Systems, Massachussets Institute of Technology, 77 Massachusetts Avenue Cambridge, MA 02139, USA.
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Ahmed WW, Williams BJ, Silver AM, Saif TA. Measuring nonequilibrium vesicle dynamics in neurons under tension. LAB ON A CHIP 2013; 13:570-578. [PMID: 23303380 DOI: 10.1039/c2lc41109a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Vesicle transport in neurons is a highly complex nonequilibrium process. Their subcellular environment is undergoing constant fluctuations from thermal energy and molecular motors. Vesicle transport is an interplay between random motion (passive) and directed motion (active) driven by molecular motors along cytoskeletal filaments. It has been shown that growth, guidance, and vesicle dynamics of neurons is affected by mechanical tension. Here we present a method to analyze vesicle transport via a temporal Mean Square Displacement (tMSD) analysis while applying mechanical strain to neurons. The tMSD analysis allows characterization of active and passive vesicle motion as well as many other parameters including: power law scaling, velocity, direction, and flux. Our results suggest: (1) The tMSD analysis is able to capture vesicle motion alternating between passive and active states, and indicates that vesicle motion in Aplysia neurons is primarily passive (exhibiting active motion for ~8% of the time). (2) Under mechanical stretch (increased neurite tension), active transport of vesicles increases to ~13%, while vesicle velocity remains unchanged. (3) Upon unstretching (decreased tension), the level of active transport returns to normal but vesicle velocity decreases. These results suggest that vesicle transport in neurons is highly sensitive to mechanical stimulation. Our method allows precise characterization of vesicle dynamics in response to applied mechanical strain.
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Affiliation(s)
- Wylie W Ahmed
- Department of Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801, USA
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38
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Nam W, Epureanu BI. The effects of viscoelastic fluid on kinesin transport. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:375103. [PMID: 22842317 DOI: 10.1088/0953-8984/24/37/375103] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Kinesins are molecular motors which transport various cargoes in the cytoplasm of cells and are involved in cell division. Previous models for kinesins have only targeted their in vitro motion. Thus, their applicability is limited to kinesin moving in a fluid with low viscosity. However, highly viscoelastic fluids have considerable effects on the movement of kinesin. For example, the high viscosity modifies the relation between the load and the speed of kinesin. While the velocity of kinesin has a nonlinear dependence with respect to the load in environments with low viscosity, highly viscous forces change that behavior. Also, the elastic nature of the fluid changes the velocity of kinesin. The new mechanistic model described in this paper considers the viscoelasticity of the fluid using subdiffusion. The approach is based on a generalized Langevin equation and fractional Brownian motion. Results show that a single kinesin has a maximum velocity when the ratio between the viscosity and elasticity is about 0.5. Additionally, the new model is able to capture the transient dynamics, which allows the prediction of the motion of kinesin under time varying loads.
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Affiliation(s)
- Woochul Nam
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA
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Burgo A, Proux-Gillardeaux V, Sotirakis E, Bun P, Casano A, Verraes A, Liem RKH, Formstecher E, Coppey-Moisan M, Galli T. A molecular network for the transport of the TI-VAMP/VAMP7 vesicles from cell center to periphery. Dev Cell 2012; 23:166-80. [PMID: 22705394 DOI: 10.1016/j.devcel.2012.04.019] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 03/12/2012] [Accepted: 04/16/2012] [Indexed: 12/15/2022]
Abstract
The compartmental organization of eukaryotic cells is maintained dynamically by vesicular trafficking. SNARE proteins play a crucial role in intracellular membrane fusion and need to be targeted to their proper donor or acceptor membrane. The molecular mechanisms that allow for the secretory vesicles carrying the v-SNARE TI-VAMP/VAMP7 to leave the cell center, load onto microtubules, and reach the periphery to mediate exocytosis are largely unknown. Here, we show that the TI-VAMP/VAMP7 partner Varp, a Rab21 guanine nucleotide exchange factor, interacts with GolginA4 and the kinesin 1 Kif5A. Activated Rab21-GTP in turn binds to MACF1, an actin and microtubule regulator, which is itself a partner of GolginA4. These components are required for directed movement of TI-VAMP/VAMP7 vesicles from the cell center to the cell periphery. The molecular mechanisms uncovered here suggest an integrated view of the transport of vesicles carrying a specific v-SNARE toward the cell surface.
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Affiliation(s)
- Andrea Burgo
- Institut Jacques Monod, UMR 7592, CNRS, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
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40
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Subpixel colocalization reveals amyloid precursor protein-dependent kinesin-1 and dynein association with axonal vesicles. Proc Natl Acad Sci U S A 2012; 109:8582-7. [PMID: 22582169 DOI: 10.1073/pnas.1120510109] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Intracellular transport of vesicles and organelles along microtubules is powered by kinesin and cytoplasmic dynein molecular motors. Both motors can attach to the same cargo and thus must be coordinated to ensure proper distribution of intracellular materials. Although a number of hypotheses have been proposed to explain how these motors are coordinated, considerable uncertainty remains, in part because of the absence of methods for assessing motor subunit composition on individual vesicular cargos. We developed a robust quantitative immunofluorescence method based on subpixel colocalization to elucidate relative kinesin-1 and cytoplasmic dynein motor subunit composition of individual, endogenous amyloid precursor protein (APP) vesicles in mouse hippocampal cells. The resulting method and data allow us to test a key in vivo prediction of the hypothesis that APP can recruit kinesin-1 to APP vesicles in neuronal axons. We found that APP levels are well-correlated with the amount of the light chain of kinesin-1 (KLC1) and the heavy chain of cytoplasmic dynein (DHC1) on vesicles. In addition, genetic reduction of APP diminishes KLC1 and DHC1 levels on APP cargos. Finally, our data reveal that reduction of KLC1 leads to decreased levels of DHC1 on APP vesicles, suggesting that KLC1 is necessary for the association of DHC1 to these cargos, and help to explain previously reported retrograde transport defects generated when kinesin-1 is reduced.
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Oyama K, Takabayashi M, Takei Y, Arai S, Takeoka S, Ishiwata S, Suzuki M. Walking nanothermometers: spatiotemporal temperature measurement of transported acidic organelles in single living cells. LAB ON A CHIP 2012; 12:1591-3. [PMID: 22437040 DOI: 10.1039/c2lc00014h] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We fabricated fluorescent nanoparticles which monitor temperature changes without sensitivity to pH (4-10) and ionic strength (0-500 mM). The nanothermometers spontaneously enter living HeLa cells via endocytosis, enclosed in acidic organelles, i.e., endosome/lysosome, and then transported along microtubules in a temperature-dependent manner, working as "walking nanothermometers".
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Affiliation(s)
- Kotaro Oyama
- Department of Physics, School of Advanced Science and Engineering, Waseda University, Tokyo, Japan
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McKinley SA, Athreya A, Fricks J, Kramer PR. Asymptotic analysis of microtubule-based transport by multiple identical molecular motors. J Theor Biol 2012; 305:54-69. [PMID: 22575549 DOI: 10.1016/j.jtbi.2012.03.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 03/09/2012] [Accepted: 03/27/2012] [Indexed: 12/25/2022]
Abstract
We describe a system of stochastic differential equations (SDEs) which model the interaction between processive molecular motors, such as kinesin and dynein, and the biomolecular cargo they tow as part of microtubule-based intracellular transport. We show that the classical experimental environment fits within a parameter regime which is qualitatively distinct from conditions one expects to find in living cells. Through an asymptotic analysis of our system of SDEs, we develop a means for applying in vitro observations of the nonlinear response by motors to forces induced on the attached cargo to make analytical predictions for two parameter regimes that have thus far eluded direct experimental observation: (1) highly viscous in vivo transport and (2) dynamics when multiple identical motors are attached to the cargo and microtubule.
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Affiliation(s)
- Scott A McKinley
- Department of Mathematics, University of Florida, Gainesville, FL 32611, USA.
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Abstract
Astroglial cells, due to their passive electrical properties, were long considered subservient to neurons and to merely provide the framework and metabolic support of the brain. Although astrocytes do play such structural and housekeeping roles in the brain, these glial cells also contribute to the brain's computational power and behavioural output. These more active functions are endowed by the Ca2+-based excitability displayed by astrocytes. An increase in cytosolic Ca2+ levels in astrocytes can lead to the release of signalling molecules, a process termed gliotransmission, via the process of regulated exocytosis. Dynamic components of astrocytic exocytosis include the vesicular-plasma membrane secretory machinery, as well as the vesicular traffic, which is governed not only by general cytoskeletal elements but also by astrocyte-specific IFs (intermediate filaments). Gliotransmitters released into the ECS (extracellular space) can exert their actions on neighbouring neurons, to modulate synaptic transmission and plasticity, and to affect behaviour by modulating the sleep homoeostat. Besides these novel physiological roles, astrocytic Ca2+ dynamics, Ca2+-dependent gliotransmission and astrocyte–neuron signalling have been also implicated in brain disorders, such as epilepsy. The aim of this review is to highlight the newer findings concerning Ca2+ signalling in astrocytes and exocytotic gliotransmission. For this we report on Ca2+ sources and sinks that are necessary and sufficient for regulating the exocytotic release of gliotransmitters and discuss secretory machinery, secretory vesicles and vesicle mobility regulation. Finally, we consider the exocytotic gliotransmission in the modulation of synaptic transmission and plasticity, as well as the astrocytic contribution to sleep behaviour and epilepsy.
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Reis GF, Yang G, Szpankowski L, Weaver C, Shah SB, Robinson JT, Hays TS, Danuser G, Goldstein LSB. Molecular motor function in axonal transport in vivo probed by genetic and computational analysis in Drosophila. Mol Biol Cell 2012; 23:1700-14. [PMID: 22398725 PMCID: PMC3338437 DOI: 10.1091/mbc.e11-11-0938] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Amyloid precursor protein (APP) vesicle movement by kinesin-1 and cytoplasmic dynein exhibits kinesin-1–dependent velocity. Our data also suggest that kinesin-1 and cytoplasmic dynein motors assemble in stable mixtures on APP vesicles and that their direction and velocity are controlled at least in part by dynein IC. Bidirectional axonal transport driven by kinesin and dynein along microtubules is critical to neuronal viability and function. To evaluate axonal transport mechanisms, we developed a high-resolution imaging system to track the movement of amyloid precursor protein (APP) vesicles in Drosophila segmental nerve axons. Computational analyses of a large number of moving vesicles in defined genetic backgrounds with partial reduction or overexpression of motor proteins enabled us to test with high precision existing and new models of motor activity and coordination in vivo. We discovered several previously unknown features of vesicle movement, including a surprising dependence of anterograde APP vesicle movement velocity on the amount of kinesin-1. This finding is largely incompatible with the biophysical properties of kinesin-1 derived from in vitro analyses. Our data also suggest kinesin-1 and cytoplasmic dynein motors assemble in stable mixtures on APP vesicles and their direction and velocity are controlled at least in part by dynein intermediate chain.
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Affiliation(s)
- Gerald F Reis
- Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA
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45
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Steketee MB, Goldberg JL. Signaling endosomes and growth cone motility in axon regeneration. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2012; 106:35-73. [PMID: 23211459 DOI: 10.1016/b978-0-12-407178-0.00003-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
During development and regeneration, growth cones guide neurites to their targets by altering their motility in response to extracellular guidance cues. One class of cues critical to nervous system development is the neurotrophins. Neurotrophin binding to their cognate receptors stimulates their endocytosis into signaling endosomes. Current data indicate that the spatiotemporal localization of signaling endosomes can direct diverse processes regulating cell motility, including membrane trafficking, cytoskeletal remodeling, adhesion dynamics, and local translation. Recent experiments manipulating signaling endosome localization in neuronal growth cones support these views and place the neurotrophin signaling endosome in a central role regulating growth cone motility during axon growth and regeneration.
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KLUMPP STEFAN, MÜLLER MELANIEJI, LIPOWSKY REINHARD. COOPERATIVE TRANSPORT BY SMALL TEAMS OF MOLECULAR MOTORS. ACTA ACUST UNITED AC 2011. [DOI: 10.1142/s1793048006000288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Molecular motors power directed transport of cargoes within cells. Even if a single motor is sufficient to transport a cargo, motors often cooperate in small teams. We discuss the cooperative cargo transport by several motors theoretically and explore some of its properties. In particular we emphasize how motor teams can drag cargoes through a viscous environment.
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Affiliation(s)
- STEFAN KLUMPP
- Center for Theoretical Biological Physics, University of California at San Diego, 9500 Gilman Drive, La Jolla CA 92109-0374, USA
| | - MELANIE J. I. MÜLLER
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
| | - REINHARD LIPOWSKY
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
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47
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LIPOWSKY REINHARD, BEEG JANINA, DIMOVA RUMIANA, KLUMPP STEFAN, LIEPELT STEFFEN, MÜLLER MELANIEJI, VALLERIANI ANGELO. ACTIVE BIO-SYSTEMS: FROM SINGLE MOTOR MOLECULES TO COOPERATIVE CARGO TRANSPORT. ACTA ACUST UNITED AC 2011. [DOI: 10.1142/s1793048009000946] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Living cells contain a large number of molecular motors that convert the chemical energy released from nucleotide hydrolysis into mechanical work. This review focusses on stepping motors that move along cytoskeletal filaments. The behavior of these motors involves three distinct nonequilibrium processes that cover a wide range of length and time scales: (i) Directed stepping of single motors bound to a filament; (ii) Composite motor walks of single motors consisting of directed stepping interrupted by diffusive motion; and (iii) Cooperative transport by teams of several motors. On the molecular scale, the energy conversion of these motors leads to single steps along the filaments with a step size of about 10 nm. The corresponding chemomechanical coupling is governed by several distinct motor cycles, which represent the dominant pathways for different values of nucleotide concentrations and load force. For the kinesin motor, the competition of two such cycles determines the stall force, at which the motor velocity vanishes and the motor reverses the direction of its motion. Because of thermal noise, the stepping motors unbind from the filaments after a certain run time and run length. For kinesin, the run time is about 1 s and the run length is about 1 μm for high ATP concentration and low load force. On length scales that are large compared to the run length, a single motor undergoes composite walks consisting of directed stepping interrupted by diffusive motion. The relative importance of bound and unbound motor states depends on the binding and unbinding rates of the motors. The effective transport velocity and diffusion coefficient of the motors are determined by the geometry of the compartments, in which the motors move. The effective diffusion coefficient can be enhanced by several orders of magnitude if the motors undergo active diffusion by interacting with certain filament patterns. In vivo, stepping motors are responsible for the transport of vesicles and other types of intracellular cargo particles that shuttle between the different cell compartments. This cargo transport is usually performed by teams of motors. If all motors belong to the same molecular species, the cooperative action of the motors leads to uni-directional transport with a strongly increased run length and to a characteristic force dependence of the velocity distributions. If two antagonistic species of motors pull on the cargo, they perform a stochastic tug-of-war, which is characterized by a subtle force balance between the two motor teams and leads to seven distinct patterns of uni- and bi-directional transport. So far, all experimental observations on bi-directional transport are consistent with such a tug-of-war. Finally, the traffic of interacting motors is also briefly discussed. Depending on their mutual interactions and the compartment geometry, the motors form various spatio-temporal patterns such as traffic jams, and undergo nonequilibrium phase transitions between such transport patterns.
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Affiliation(s)
- REINHARD LIPOWSKY
- Department of Theory & Bio-Systems, MPI of Colloids and Interfaces, Science Park, 14424 Potsdam, Germany
| | - JANINA BEEG
- Department of Theory & Bio-Systems, MPI of Colloids and Interfaces, Science Park, 14424 Potsdam, Germany
| | - RUMIANA DIMOVA
- Department of Theory & Bio-Systems, MPI of Colloids and Interfaces, Science Park, 14424 Potsdam, Germany
| | - STEFAN KLUMPP
- Department of Theory & Bio-Systems, MPI of Colloids and Interfaces, Science Park, 14424 Potsdam, Germany
| | - STEFFEN LIEPELT
- Department of Theory & Bio-Systems, MPI of Colloids and Interfaces, Science Park, 14424 Potsdam, Germany
| | - MELANIE J. I. MÜLLER
- Department of Theory & Bio-Systems, MPI of Colloids and Interfaces, Science Park, 14424 Potsdam, Germany
| | - ANGELO VALLERIANI
- Department of Theory & Bio-Systems, MPI of Colloids and Interfaces, Science Park, 14424 Potsdam, Germany
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48
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Abstract
Long-distance transport in eukaryotic cells is driven by molecular motors that move along microtubule tracks. Molecular motors of the kinesin superfamily contain a kinesin motor domain attached to family-specific sequences for cargo binding, regulation, and oligomerization. The biochemical and biophysical properties of the kinesin motor domain have been widely studied, yet little is known about how kinesin motors work in the complex cellular environment. We discuss recent studies on the three major families involved in intracellular transport (kinesin-1, kinesin-2, and kinesin-3) that have begun to bridge the gap in knowledge between the in vitro and in vivo behaviors of kinesin motors. These studies have increased our understanding of how kinesin subunits assemble to produce a functional motor, how kinesin motors are affected by biochemical cues and obstacles present on cellular microtubules, and how multiple motors on a cargo surface can work collectively for increased force production and travel distance.
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Affiliation(s)
- Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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Fallesen TL, Macosko JC, Holzwarth G. Force-velocity relationship for multiple kinesin motors pulling a magnetic bead. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 40:1071-9. [PMID: 21735291 DOI: 10.1007/s00249-011-0724-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Revised: 06/07/2011] [Accepted: 06/12/2011] [Indexed: 11/25/2022]
Abstract
Although the velocity of single kinesin motors against an opposing force F of 0-10 pN is well known, the behavior of multiple kinesin motors working to overcome a larger load is still poorly understood. We have carried out gliding assays in which 3-7 Drosophila kinesin-1 motors moved a microtubule at 200-700 μm/s against a 0-31 pN load at saturating [ATP]. The load F was generated by applying a spatially uniform magnetic field gradient to a superparamagnetic bead attached to the (+) end of the microtubule. When F was scaled by the average number of motors [Symbol: see text]n[Symbol: see text], the force-velocity relationship for multiple motors was similar to the force-velocity relationship for a single motor, supporting a minimal load-sharing model. The velocity distribution at low load has a single mode consistent with rapid fluctuations of n. However, against a load of 2.5-4.7 pN/motor, additional modes appeared at lower velocity. These observations support the Klumpp-Lipowsky model of multimotor transport [Proc Natl Acad Sci USA 102. 17284-17289 (2005)].
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Affiliation(s)
- Todd L Fallesen
- Department of Physics, Wake Forest University, PO Box 7507, Winston-Salem, NC 27109, USA
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50
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Kuznetsov AV. Method of modelling intracellular transport in branching neurites: application to axons and dendrites of Drosophila sensory neurons. Comput Methods Biomech Biomed Engin 2011; 14:239-51. [PMID: 20419522 DOI: 10.1080/10255841003664727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This paper develops a method of calculating the transport of intracellular organelles in neurons with branching neurites which is based on the Smith-Simmons equations of motor-assisted transport. The method is aimed at understanding the effects of microtubule (MT) polarity orientation in branching neurites on transport of organelles at the fundamental level. The method is applied to calculating the organelle transport in axons and dendrites of Drosophila neurons, using the map of MT orientation in such neurons developed by Stone et al. (Mol Biol Cell 19:4122-4129, 2008). The proximal dendrite is assumed to branch and form two distal dendrites. Two different MT polarity arrangements in a proximal dendrite are considered, and implications of these MT arrangements on organelle transport are analysed. It is demonstrated that the MT arrangement found in Drosophila dendrites (MTs have their minus ends out in a proximal dendrite) results in much more efficient motor-driven transport than the structure with a mixed MT orientation in proximal dendrites.
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Affiliation(s)
- A V Kuznetsov
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910, USA.
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