scholarly journals Formation of α-synuclein Lewy neurite–like aggregates in axons impedes the transport of distinct endosomes

2014 ◽  
Vol 25 (25) ◽  
pp. 4010-4023 ◽  
Author(s):  
Laura A. Volpicelli-Daley ◽  
Karen L. Gamble ◽  
Christine E. Schultheiss ◽  
Dawn M. Riddle ◽  
Andrew B. West ◽  
...  
Keyword(s):  
Axonal Transport ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Imaging ◽  
Primary Neurons ◽  
Lewy Neurites ◽  
Trkb Receptor ◽  
Neurodegenerative Process ◽  
Early Effects ◽  
Lewy Neurite

Aggregates of α-synuclein (α-syn) accumulate in neurons in Parkinson's disease and other synucleinopathies. These inclusions predominantly localize to axons even in the early stages of the disease, but their affect on axon function has remained unknown. Previously we established a model in which the addition of preformed α-syn fibrils to primary neurons seeds formation of insoluble α-syn inclusions built from endogenously expressed α-syn that closely recapitulate the neuropathological phenotypes of Lewy neurites found in human diseased brains. Here we show, using live-cell imaging, that immobile α-syn inclusions accumulate in axons from the recruitment of α-syn located on mobile α-syn–positive vesicles. Ultrastructural analyses and live imaging demonstrate that α-syn accumulations do not cause a generalized defect in axonal transport; the inclusions do not fill the axonal cytoplasm, disrupt the microtubule cytoskeleton, or affect the transport of synaptophysin or mitochondria. However, the α-syn aggregates impair the transport of Rab7 and TrkB receptor–containing endosomes, as well as autophagosomes. In addition, the TrkB receptor–associated signaling molecule pERK5 accumulates in α-syn aggregate–bearing neurons. Thus α-syn pathology impairs axonal transport of signaling and degradative organelles. These early effects of α-syn accumulations may predict points of intervention in the neurodegenerative process.

scholarly journals Rapid Morphological and Cytoskeletal Response to Microgravity in Human Primary Macrophages

2019 ◽  
Vol 20 (10) ◽  
pp. 2402 ◽  
Author(s):  
Cora Sandra Thiel ◽  
Svantje Tauber ◽  
Beatrice Lauber ◽  
Jennifer Polzer ◽  
Christian Seebacher ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Live Imaging ◽  
Live Cell ◽  
Cellular Structures ◽  
Microgravity Environment ◽  
Confocal Laser ◽  
Human Macrophages ◽  
Imaging Experiment

The FLUMIAS (Fluorescence-Microscopic Analyses System for Life-Cell-Imaging in Space) confocal laser spinning disk fluorescence microscope represents a new imaging capability for live cell imaging experiments on suborbital ballistic rocket missions. During the second pioneer mission of this microscope system on the TEXUS-54 suborbital rocket flight, we developed and performed a live imaging experiment with primary human macrophages. We simultaneously imaged four different cellular structures (nucleus, cytoplasm, lysosomes, actin cytoskeleton) by using four different live cell dyes (Nuclear Violet, Calcein, LysoBrite, SiR-actin) and laser wavelengths (405, 488, 561, and 642 nm), and investigated the cellular morphology in microgravity (10−4 to 10−5 g) over a period of about six minutes compared to 1 g controls. For live imaging of the cytoskeleton during spaceflight, we combined confocal laser microscopy with the SiR-actin probe, a fluorogenic silicon-rhodamine (SiR) conjugated jasplakinolide probe that binds to F-actin and displays minimal toxicity. We determined changes in 3D cell volume and surface, nuclear volume and in the actin cytoskeleton, which responded rapidly to the microgravity environment with a significant reduction of SiR-actin fluorescence after 4–19 s microgravity, and adapted subsequently until 126–151 s microgravity. We conclude that microgravity induces geometric cellular changes and rapid response and adaptation of the potential gravity-transducing cytoskeleton in primary human macrophages.

scholarly journals Role of cytoplasmic dynein in the axonal transport of microtubules and neurofilaments

2005 ◽  
Vol 168 (5) ◽  
pp. 697-703 ◽  
Author(s):  
Yan He ◽  
Franto Francis ◽  
Kenneth A. Myers ◽  
Wenqian Yu ◽  
Mark M. Black ◽  
...  
Keyword(s):  
Rna Interference ◽  
Axonal Transport ◽  
Heavy Chain ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Sympathetic Neurons ◽  
Cytoplasmic Dynein ◽  
Live Cell ◽  
Cytoskeletal Elements

Recent studies have shown that the transport of microtubules (MTs) and neurofilaments (NFs) within the axon is rapid, infrequent, asynchronous, and bidirectional. Here, we used RNA interference to investigate the role of cytoplasmic dynein in powering these transport events. To reveal transport of MTs and NFs, we expressed EGFP-tagged tubulin or NF proteins in cultured rat sympathetic neurons and performed live-cell imaging of the fluorescent cytoskeletal elements in photobleached regions of the axon. The occurrence of anterograde MT and retrograde NF movements was significantly diminished in neurons that had been depleted of dynein heavy chain, whereas the occurrence of retrograde MT and anterograde NF movements was unaffected. These results support a cargo model for NF transport and a sliding filament model for MT transport.

scholarly journals Polarity sorting of axonal microtubules: a computational study

2017 ◽  
Vol 28 (23) ◽  
pp. 3271-3285 ◽  
Author(s):  
Erin M. Craig ◽  
Howard T. Yeung ◽  
Anand N. Rao ◽  
Peter W. Baas
Keyword(s):  
Computational Model ◽  
Axonal Transport ◽  
Cell Body ◽  
Live Cell Imaging ◽  
Motor Proteins ◽  
Cell Imaging ◽  
Computational Study ◽  
Cytoplasmic Dynein ◽  
Cross Linker ◽  
Static Cross

We present a computational model to test a “polarity sorting” mechanism for microtubule (MT) organization in developing axons. We simulate the motor-based axonal transport of short MTs to test the hypothesis that immobilized cytoplasmic dynein motors transport short MTs with their plus ends leading, so “mal-oriented” MTs with minus-end-out are transported toward the cell body while “correctly” oriented MTs are transported in the anterograde direction away from the soma. We find that dynein-based transport of short MTs can explain the predominately plus-end-out polarity pattern of axonal MTs but that transient attachments of plus-end-directed motor proteins and nonmotile cross-linker proteins are needed to explain the frequent pauses and occasional reversals observed in live-cell imaging of MT transport. Static cross-linkers increase the likelihood of a stalled “tug-of-war” between retrograde and anterograde forces on the MT, providing an explanation for the frequent pauses of short MTs and the immobility of longer MTs. We predict that inhibition of the proposed static cross-linker will produce disordered transport of short MTs and increased mobility of longer MTs. We also predict that acute inhibition of cytoplasmic dynein will disrupt the polarity sorting of MTs by increasing the likelihood of “incorrect” sorting of MTs by plus-end-directed motors.

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