scholarly journals A PIK3C3–Ankyrin-B–Dynactin pathway promotes axonal growth and multiorganelle transport

2014 ◽  
Vol 207 (6) ◽  
pp. 735-752 ◽  
Author(s):  
Damaris Nadia Lorenzo ◽  
Alexandra Badea ◽  
Jonathan Davis ◽  
Janell Hostettler ◽  
Jiang He ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Synaptic Vesicles ◽  
Hippocampal Neurons ◽  
Axon Growth ◽  
Retrograde Transport ◽  
Organelle Transport ◽  
Class Iii ◽  
Functional Relationships ◽  
Range Transport ◽  
Ankyrin B

Axon growth requires long-range transport of organelles, but how these cargoes recruit their motors and how their traffic is regulated are not fully resolved. In this paper, we identify a new pathway based on the class III PI3-kinase (PIK3C3), ankyrin-B (AnkB), and dynactin, which promotes fast axonal transport of synaptic vesicles, mitochondria, endosomes, and lysosomes. We show that dynactin associates with cargo through AnkB interactions with both the dynactin subunit p62 and phosphatidylinositol 3-phosphate (PtdIns(3)P) lipids generated by PIK3C3. AnkB knockout resulted in shortened axon tracts and marked reduction in membrane association of dynactin and dynein, whereas it did not affect the organization of spectrin–actin axonal rings imaged by 3D-STORM. Loss of AnkB or of its linkages to either p62 or PtdIns(3)P or loss of PIK3C3 all impaired organelle transport and particularly retrograde transport in hippocampal neurons. Our results establish new functional relationships between PIK3C3, dynactin, and AnkB that together promote axonal transport of organelles and are required for normal axon length.

Organelle motility and metabolism in axons vs dendrites of cultured hippocampal neurons

1996 ◽  
Vol 109 (5) ◽  
pp. 971-980 ◽  
Author(s):  
C.C. Overly ◽  
H.I. Rieff ◽  
P.J. Hollenbeck
Keyword(s):  
Regional Variation ◽  
Hippocampal Neurons ◽  
Retrograde Transport ◽  
Organelle Transport ◽  
Microtubule Polarity ◽  
Large Phase ◽  
Organelle Motility ◽  
The Difference ◽  
Metabolic Properties ◽  
Cultured Hippocampal Neurons

Regional regulation of organelle transport seems likely to play an important role in establishing and maintaining distinct axonal and dendritic domains in neurons, and in managing differences in local metabolic demands. In addition, known differences in microtubule polarity and organization between axons and dendrites along with the directional selectivity of microtubule-based motor proteins suggest that patterns of organelle transport may differ in these two process types. To test this hypothesis, we compared the patterns of movement of different organelle classes in axons and different dendritic regions of cultured embryonic rat hippocampal neurons. We first examined the net direction of organelle transport in axons, proximal dendrites and distal dendrites by video-enhanced phase-contrast microscopy. We found significant regional variation in the net transport of large phase-dense vesicular organelles: they exhibited net retrograde transport in axons and distal dendrites, whereas they moved equally in both directions in proximal dendrites. No significant regional variation was found in the net transport of mitochondria or macropinosomes. Analysis of individual organelle motility revealed three additional differences in organelle transport between the two process types. First, in addition to the difference in net transport direction, the large phase-dense organelles exhibited more persistent changes in direction in proximal dendrites where microtubule polarity is mixed than in axons where microtubule polarity is uniform. Second, while the net direction of mitochondrial transport was similar in both processes, twice as many mitochondria were motile in axons than in dendrites. Third, the mean excursion length of moving mitochondria was significantly longer in axons than in dendrites. To determine whether there were regional differences in metabolic activity that might account for these motility differences, we labeled mitochondria with the vital dye, JC-1, which reveals differences in mitochondrial transmembrane potential. Staining of neurons with this dye revealed a greater proportion of highly charged, more metabolically active, mitochondria in dendrites than in axons. Together, our data reveal differences in organelle motility and metabolic properties in axons and dendrites of cultured hippocampal neurons.

scholarly journals βII-spectrin promotes mouse brain connectivity through stabilizing axonal plasma membranes and enabling axonal organelle transport

2019 ◽  
Vol 116 (31) ◽  
pp. 15686-15695 ◽  
Author(s):  
Damaris N. Lorenzo ◽  
Alexandra Badea ◽  
Ruobo Zhou ◽  
Peter J. Mohler ◽  
Xiaowei Zhuang ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Plasma Membranes ◽  
Brain Connectivity ◽  
Axon Growth ◽  
Membrane Skeleton ◽  
Lipid Binding ◽  
Organelle Transport ◽  
Double Knockout ◽  
Micrometer Scale

βII-spectrin is the generally expressed member of the β-spectrin family of elongated polypeptides that form micrometer-scale networks associated with plasma membranes. We addressed in vivo functions of βII-spectrin in neurons by knockout of βII-spectrin in mouse neural progenitors. βII-spectrin deficiency caused severe defects in long-range axonal connectivity and axonal degeneration. βII-spectrin–null neurons exhibited reduced axon growth, loss of actin–spectrin-based periodic membrane skeleton, and impaired bidirectional axonal transport of synaptic cargo. We found that βII-spectrin associates with KIF3A, KIF5B, KIF1A, and dynactin, implicating spectrin in the coupling of motors and synaptic cargo. βII-spectrin required phosphoinositide lipid binding to promote axonal transport and restore axon growth. Knockout of ankyrin-B (AnkB), a βII-spectrin partner, primarily impaired retrograde organelle transport, while double knockout of βII-spectrin and AnkB nearly eliminated transport. Thus, βII-spectrin promotes both axon growth and axon stability through establishing the actin–spectrin-based membrane-associated periodic skeleton as well as enabling axonal transport of synaptic cargo.

scholarly journals Effects of the dynein inhibitor dynarrestin on the number of motor proteins transporting synaptic cargos

2020 ◽  
Author(s):  
Kumiko Hayashi ◽  
Miki G. Miyamoto ◽  
Shinsuke Niwa
Keyword(s):  
Axonal Transport ◽  
Optical Tweezers ◽  
Hippocampal Neurons ◽  
Motor Proteins ◽  
Force Measurement ◽  
Retrograde Transport ◽  
Long Distance ◽  
Anterograde Transport ◽  
Non Invasive ◽  
Physical Measurements

AbstractSynaptic cargo transport by kinesin and dynein in hippocampal neurons was investigated using non-invasive measurements of transport force based on non-equilibrium statistical mechanics. Although direct physical measurements such as force measurement using optical tweezers are difficult in an intracellular environment, the non-invasive 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 anterograde transport. In the future, these measurements may be used to quantify the damage to axonal transport resulting from neuronal diseases including Alzheimer’s, Parkinson’s, and Huntington’s diseases.

scholarly journals Amyloid-β oligomers induce tau-independent disruption of BDNF axonal transport via calcineurin activation in cultured hippocampal neurons

2013 ◽  
Vol 24 (16) ◽  
pp. 2494-2505 ◽  
Author(s):  
Elisa M. Ramser ◽  
Kathlyn J. Gan ◽  
Helena Decker ◽  
Emily Y. Fan ◽  
Matthew M. Suzuki ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Hippocampal Neurons ◽  
Glycogen Synthase ◽  
Amyloid Β ◽  
Protein Phosphatase 1 ◽  
Organelle Transport ◽  
Calcium Dependent ◽  
Pathological Event ◽  
Cultured Hippocampal Neurons

Disruption of fast axonal transport (FAT) is an early pathological event in Alzheimer's disease (AD). Soluble amyloid-β oligomers (AβOs), increasingly recognized as proximal neurotoxins in AD, impair organelle transport in cultured neurons and transgenic mouse models. AβOs also stimulate hyperphosphorylation of the axonal microtubule-associated protein, tau. However, the role of tau in FAT disruption is controversial. Here we show that AβOs reduce vesicular transport of brain-derived neurotrophic factor (BDNF) in hippocampal neurons from both wild-type and tau-knockout mice, indicating that tau is not required for transport disruption. FAT inhibition is not accompanied by microtubule destabilization or neuronal death. Significantly, inhibition of calcineurin (CaN), a calcium-dependent phosphatase implicated in AD pathogenesis, rescues BDNF transport. Moreover, inhibition of protein phosphatase 1 and glycogen synthase kinase 3β, downstream targets of CaN, prevents BDNF transport defects induced by AβOs. We further show that AβOs induce CaN activation through nonexcitotoxic calcium signaling. Results implicate CaN in FAT regulation and demonstrate that tau is not required for AβO-induced BDNF transport disruption.

scholarly journals Disease-associated mutations in human BICD2 hyperactivate motility of dynein–dynactin

2017 ◽  
Vol 216 (10) ◽  
pp. 3051-3060 ◽  
Author(s):  
Walter Huynh ◽  
Ronald D. Vale
Keyword(s):  
Spinal Muscular Atrophy ◽  
Hippocampal Neurons ◽  
Muscular Atrophy ◽  
Membrane Vesicle ◽  
Point Mutations ◽  
Neurite Growth ◽  
Retrograde Transport ◽  
Organelle Transport ◽  
Dominant Form

Bicaudal D2 (BICD2) joins dynein with dynactin into a ternary complex (termed DDB) capable of processive movement. Point mutations in the BICD2 gene have been identified in patients with a dominant form of spinal muscular atrophy, but how these mutations cause disease is unknown. To investigate this question, we have developed in vitro motility assays with purified DDB and BICD2’s membrane vesicle partner, the GTPase Rab6a. Rab6a–GTP, either in solution or bound to artificial liposomes, released BICD2 from an autoinhibited state and promoted robust dynein–dynactin transport. In these assays, BICD2 mutants showed an enhanced ability to form motile DDB complexes. Increased retrograde transport by BICD2 mutants also was observed in cells using an inducible organelle transport assay. When overexpressed in rat hippocampal neurons, the hyperactive BICD2 mutants decreased neurite growth. Our results reveal that dominant mutations in BICD2 hyperactivate DDB motility and suggest that an imbalance of minus versus plus end–directed microtubule motility in neurons may underlie spinal muscular atrophy.

scholarly journals Disease-Associated Mutations in Human BICD2 Hyperactivate Motility of Dynein-Dynactin

2017 ◽  
Author(s):  
Walter Huynh ◽  
Ronald D. Vale
Keyword(s):  
Spinal Muscular Atrophy ◽  
Hippocampal Neurons ◽  
Muscular Atrophy ◽  
Membrane Vesicle ◽  
Point Mutations ◽  
Neurite Growth ◽  
Retrograde Transport ◽  
Organelle Transport ◽  
Dominant Form

AbstractBicaudal D2 (BICD2) joins dynein with dynactin into a ternary complex (termed DDB) capable of processive movement. Point mutations in the BICD2 gene have been identified in patients with a dominant form of spinal muscular atrophy, but how these mutations cause disease is unknown. To investigate this question, we have developed in vitro motility assays with purified DDB and BICD2’s membrane vesicle partner, the GTPase Rab6a. Rab6a-GTP, either in solution or bound to artificial liposomes, released BICD2 from an autoinhibited state and promoted robust dynein-dynactin transport. In these assays, BICD2 mutants showed an enhanced ability to form motile DDB complexes. Increased retrograde transport by BICD2 mutants also was observed in cells using an inducible organelle transport assay. When overexpressed in rat hippocampal neurons, the hyperactive BICD2 mutants decreased neurite growth. Our results reveal that dominant mutations in BICD2 hyperactivate DDB motility and suggest that an imbalance of minus- versus plus-end-directed microtubule motility in neurons may underlie spinal muscular atrophy.

scholarly journals BDNF mobilizes synaptic vesicles and enhances synapse formation by disrupting cadherin–β-catenin interactions

2006 ◽  
Vol 174 (2) ◽  
pp. 289-299 ◽  
Author(s):  
Shernaz X. Bamji ◽  
Beatriz Rico ◽  
Nikole Kimes ◽  
Louis F. Reichardt
Keyword(s):  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Synapse Formation ◽  
Time Lapse ◽  
Synapse Density ◽  
Vesicle Mobility ◽  
Small Clusters ◽  
Vertebrate Central Nervous System

Neurons of the vertebrate central nervous system have the capacity to modify synapse number, morphology, and efficacy in response to activity. Some of these functions can be attributed to activity-induced synthesis and secretion of the neurotrophin brain-derived neurotrophic factor (BDNF); however, the molecular mechanisms by which BDNF mediates these events are still not well understood. Using time-lapse confocal analysis, we show that BDNF mobilizes synaptic vesicles at existing synapses, resulting in small clusters of synaptic vesicles “splitting” away from synaptic sites. We demonstrate that BDNF's ability to mobilize synaptic vesicle clusters depends on the dissociation of cadherin–β-catenin adhesion complexes that occurs after tyrosine phosphorylation of β-catenin. Artificially maintaining cadherin–β-catenin complexes in the presence of BDNF abolishes the BDNF-mediated enhancement of synaptic vesicle mobility, as well as the longer-term BDNF-mediated increase in synapse number. Together, this data demonstrates that the disruption of cadherin–β-catenin complexes is an important molecular event through which BDNF increases synapse density in cultured hippocampal neurons.

A Simple Depletion Model of the Readily Releasable Pool of Synaptic Vesicles Cannot Account for Paired-Pulse Depression

2007 ◽  
Vol 97 (1) ◽  
pp. 948-950 ◽  
Author(s):  
Jane M. Sullivan
Keyword(s):  
Synaptic Vesicles ◽  
Hippocampal Neurons ◽  
Synaptic Activity ◽  
Excitatory Synapses ◽  
Short Term ◽  
Paired Pulse ◽  
Short Term Plasticity ◽  
Releasable Pool ◽  
Readily Releasable Pool ◽  
Paired Pulse Depression

Paired-pulse depression (PPD) is a form of short-term plasticity that plays a central role in processing of synaptic activity and is manifest as a decrease in the size of the response to the second of two closely timed stimuli. Despite mounting evidence to the contrary, PPD is still commonly thought to reflect depletion of the pool of synaptic vesicles available for release in response to the second stimulus. Here it is shown that PPD cannot be accounted for by depletion at excitatory synapses made by hippocampal neurons because PPD is unaffected by changes in the fraction of the readily releasable pool (RRP) released by the first of a pair of pulses.

scholarly journals Stabilization of dynamic microtubules by mDia1 drives Tau-dependent Aβ1–42 synaptotoxicity

2017 ◽  
Vol 216 (10) ◽  
pp. 3161-3178 ◽  
Author(s):  
Xiaoyi Qu ◽  
Feng Ning Yuan ◽  
Carlo Corona ◽  
Silvia Pasini ◽  
Maria Elena Pero ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Axonal Transport ◽  
Dendritic Spines ◽  
Posttranslational Modifications ◽  
Hippocampal Neurons ◽  
Neuronal Damage ◽  
Driving Factors ◽  
Hyperphosphorylated Tau ◽  
Tau Hyperphosphorylation

Oligomeric Amyloid β1–42 (Aβ) plays a crucial synaptotoxic role in Alzheimer’s disease, and hyperphosphorylated tau facilitates Aβ toxicity. The link between Aβ and tau, however, remains controversial. In this study, we find that in hippocampal neurons, Aβ acutely induces tubulin posttranslational modifications (PTMs) and stabilizes dynamic microtubules (MTs) by reducing their catastrophe frequency. Silencing or acute inhibition of the formin mDia1 suppresses these activities and corrects the synaptotoxicity and deficits of axonal transport induced by Aβ. We explored the mechanism of rescue and found that stabilization of dynamic MTs promotes tau-dependent loss of dendritic spines and tau hyperphosphorylation. Collectively, these results uncover a novel role for mDia1 in Aβ-mediated synaptotoxicity and demonstrate that inhibition of MT dynamics and accumulation of PTMs are driving factors for the induction of tau-mediated neuronal damage.

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