Cytoplasmic dynein pushes the cytoskeletal meshwork forward during axonal elongation

Roossien, Douglas H.; Lamoureux, Phillip; Miller, Kyle E.

doi:10.1242/jcs.152611

Cited by 69 publications

(106 citation statements)

References 75 publications

(125 reference statements)

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“…Additionally, we have observed MT sliding in axons as well as MTs pushing on the axon tip (9). Recent studies from other groups have also implicated MT translocation in axon extension and dendritic organization (10)(11)(12). Based on these studies, we hypothesize that kinesin-1 drives neurite extension by sliding MTs against the plasma membrane.…”

supporting

confidence: 66%

Role of kinesin-1–based microtubule sliding in Drosophila nervous system development

Winding

Kelliher

Lü

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The plus-end microtubule (MT) motor kinesin-1 is essential for normal development, with key roles in the nervous system. Kinesin-1 drives axonal transport of membrane cargoes to fulfill the metabolic needs of neurons and maintain synapses. We have previously demonstrated that kinesin-1, in addition to its well-established role in organelle transport, can drive MT-MT sliding by transporting "cargo" MTs along "track" MTs, resulting in dramatic cell shape changes. The mechanism and physiological relevance of this MT sliding are unclear. In addition to its motor domain, kinesin-1 contains a second MT-binding site, located at the C terminus of the heavy chain. Here, we mutated this C-terminal MT-binding site such that the ability of kinesin-1 to slide MTs is significantly compromised, whereas cargo transport is unaffected. We introduced this mutation into the genomic locus of kinesin-1 heavy chain (KHC), generating the Khc mutA allele. Khc mutA neurons displayed significant MT sliding defects while maintaining normal transport of many cargoes. Using this mutant, we demonstrated that MT sliding is required for axon and dendrite outgrowth in vivo. Consistent with these results, Khc mutA flies displayed severe locomotion and viability defects. To test the role of MT sliding further, we engineered a chimeric motor that actively slides MTs but cannot transport organelles. Activation of MT sliding in Khc mutA neurons using this chimeric motor rescued axon outgrowth in cultured neurons and in vivo, firmly establishing the role of sliding in axon outgrowth. These results demonstrate that MT sliding by kinesin-1 is an essential biological phenomenon required for neuronal morphogenesis and normal nervous system development.kinesin-1 | microtubules | Drosophila | axon outgrowth | dendrite outgrowth N eurons are the basic unit of the nervous system, forming vast networks throughout the body that communicate using receptorligand machinery located in long cellular projections called axons and dendrites. Learning how these processes form is key to understanding the early development and pathology of the nervous system. Microtubules (MTs) and actin microfilaments have been implicated in neurite outgrowth, with many studies focusing on the growth cone at the tip of the axon. Previous models suggest that the driving forces for neurite outgrowth are MT polymerization and the treadmilling of F-actin (1, 2). However, other studies demonstrate that F-actin is dispensable to outgrowth and neurites extend even in the absence of F-actin (3-5).Our group has found that the motor protein kinesin-1 can rearrange the MT network by sliding MTs against each other (6). We have shown that kinesin-1 is required for MT sliding in cultured neurons and kinesin-1 depletion inhibits both neurite outgrowth and regeneration (7,8). Additionally, we have observed MT sliding in axons as well as MTs pushing on the axon tip (9). Recent studies from other groups have also implicated MT translocation in axon extension and dendritic organization (10-12). Based on th...

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supporting

confidence: 66%

Role of kinesin-1–based microtubule sliding in Drosophila nervous system development

Winding

Kelliher

Lü

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…1 D). As previously described in Roossien et al (13), we used the movement of docked mitochondria as fiduciary markers for the bulk movement of the cytoskeletal meshwork. Here we classified a mitochondrion as docked if it moved at a velocity between 100 and À100 mm/h.…”

Section: Axons Are Viscous Fluids Even At Restmentioning

confidence: 99%

“…Our approach to answering this has been to track the motion of mitochondria stably docked to the cytoskeletal meshwork (13,14). Mitochondria are large organelles that can be easily visualized in low light conditions using the fluorescent dye MitoTracker (Life Technologies, Grand Island, NY).…”

Section: Introductionmentioning

confidence: 99%

“…Nonetheless, a major question that has never been directly addressed is whether net pulling or pushing forces are generated at the rear of the growth cone over the microtubule-rich region and/or along the axon. We recently reported that the microtubule-associated protein dynein generates forces that push material in neurons forward in bulk (13). In addition, Kinesin-1 has been demonstrated to drive microtubule sliding from the neuronal cell body (29).…”

Section: Introductionmentioning

confidence: 99%

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Measurement of Subcellular Force Generation in Neurons

O'Toole

Lamoureux

Miller

2015

Biophysical Journal

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Forces are important for neuronal outgrowth during the initial wiring of the nervous system and after trauma, yet subcellular force generation over the microtubule-rich region at the rear of the growth cone and along the axon has never, to our knowledge, been directly measured. Because previous studies have indicated microtubule polymerization and the microtubule-associated proteins Kinesin-1 and dynein all generate forces that push microtubules forward, a major question is whether the net forces in these regions are contractile or expansive. A challenge in addressing this is that measuring local subcellular force generation is difficult. Here we develop an analytical mathematical model that describes the relationship between unequal subcellular forces arranged in series within the neuron and the net overall tension measured externally. Using force-calibrated towing needles to measure and apply forces, in combination with docked mitochondria to monitor subcellular strain, we then directly measure force generation over the rear of the growth cone and along the axon of chick sensory neurons. We find the rear of the growth cone generates 2.0 nN of contractile force, the axon generates 0.6 nN of contractile force, and that the net overall tension generated by the neuron is 1.3 nN. This work suggests that the forward bulk flow of the cytoskeletal framework that occurs during axonal elongation and growth-cone pauses arises because strong contractile forces in the rear of the growth cone pull material forward.

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“…Perhaps more importantly, analyzing strains along the entire lengths of fibers enables assessing the injury risks to WM neural pathways or tracts, which is not possible with previous element/voxel-based studies that are limited to anatomical regions of interest (ROIs). Because axons and their bundles are neural processes that connect neuronal cell bodies and transmit information between them, 28,29 it is reasonable to assume that any damage along the axons, regardless of the location (within or outside the boundary of any traversing ROI), would constitute potential functional impairment. 20 The goal of this study was to develop a technique to evaluate e n along voxel-or anatomically constrained whole-brain tractography, which has not been performed before.…”

Section: Introductionmentioning

confidence: 99%

White Matter Injury Susceptibility via Fiber Strain Evaluation Using Whole-Brain Tractography

Zhao

Ford

Flashman

et al. 2016

Journal of Neurotrauma

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Microscale brain injury studies suggest axonal elongation as a potential mechanism for diffuse axonal injury (DAI). Recent studies have begun to incorporate white matter (WM) structural anisotropy in injury analysis, with initial evidence suggesting improved injury prediction performance. In this study, we further develop a tractography-based approach to analyze fiber strains along the entire lengths of fibers from voxel-or anatomically constrained whole-brain tractography. This technique potentially extends previous element-or voxel-based methods that instead utilize WM fiber orientations averaged from typically coarse elements or voxels. Perhaps more importantly, incorporating tractography-based axonal structural information enables assessment of the overall injury risks to functionally important neural pathways and the anatomical regions they connect, which is not possible with previous methods. A DAI susceptibility index was also established to quantify voxel-wise WM local structural integrity and tract-wise damage of individual neural pathways. This ''graded'' injury susceptibility potentially extends the commonly employed treatment of injury as a simple binary condition. As an illustration, we evaluate the DAI susceptibilities of WM voxels and transcallosal fiber tracts in three idealized head impacts. Findings suggest the potential importance of the tractography-based approach for injury prediction. These efforts may enable future studies to correlate WM mechanical responses with neuroimaging, cognitive alteration, and concussion, and to reveal the relative vulnerabilities of neural pathways and identify the most vulnerable ones in real-world head impacts.

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Cytoplasmic dynein pushes the cytoskeletal meshwork forward during axonal elongation

Cited by 69 publications

References 75 publications

Role of kinesin-1–based microtubule sliding in Drosophila nervous system development

Role of kinesin-1–based microtubule sliding in Drosophila nervous system development

Measurement of Subcellular Force Generation in Neurons

White Matter Injury Susceptibility via Fiber Strain Evaluation Using Whole-Brain Tractography

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