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  1. Article ; Online: Using Live-Cell Imaging to Measure the Effects of Pathological Proteins on Axonal Transport in Primary Hippocampal Neurons.

    Mueller, Rebecca L / Kanaan, Nicholas M / Combs, Benjamin

    Journal of visualized experiments : JoVE

    2023  , Issue 202

    Abstract: Bidirectional transport of cargos along the axon is critical for maintaining functional synapses, neural connectivity, and healthy neurons. Axonal transport is disrupted in multiple neurodegenerative diseases, and projection neurons are particularly ... ...

    Abstract Bidirectional transport of cargos along the axon is critical for maintaining functional synapses, neural connectivity, and healthy neurons. Axonal transport is disrupted in multiple neurodegenerative diseases, and projection neurons are particularly vulnerable because of the need to transport cellular materials over long distances and sustain substantial axonal mass. Pathological modifications of several disease-related proteins negatively affect transport, including tau, amyloid-β, α-synuclein, superoxide dismutase, and huntingtin, providing a potential common mechanism by which pathological proteins exert toxicity in disease. Methods to study these toxic mechanisms are necessary to understand neurodegenerative disorders and identify potential therapeutic interventions. Here, cultured primary rodent hippocampal neurons are co-transfected with multiple plasmids to study the effects of pathological proteins on fast axonal transport using live-cell confocal imaging of fluorescently-tagged cargo proteins. We begin with the harvest, dissociation, and culturing of primary hippocampal neurons from rodents. Then, we co-transfect the neurons with plasmid DNA constructs to express fluorescent-tagged cargo protein and wild-type or mutant tau (used as an exemplar of pathological proteins). Axons are identified in live cells using an antibody that binds an extracellular domain of neurofascin, an axon initial segment protein, and an axonal region of interest is imaged to measure fluorescent cargo transport. Using KymoAnalyzer, a freely available ImageJ macro, we extensively characterize the velocity, pause frequency, and directional cargo density of axonal transport, all of which may be affected by the presence of pathological proteins. Through this method, we identify a phenotype of increased cargo pause frequency associated with the expression of pathological tau protein. Additionally, gene-silencing shRNA constructs can be added to the transfection mix to test the role of other proteins in mediating transport disruption. This protocol is easily adaptable for use with other neurodegenerative disease-related proteins and is a reproducible method to study the mechanisms of how those proteins disrupt axonal transport.
    MeSH term(s) Humans ; Axonal Transport ; Neurodegenerative Diseases ; Neurons ; Axons ; Interneurons
    Language English
    Publishing date 2023-12-22
    Publishing country United States
    Document type Journal Article ; Video-Audio Media
    ZDB-ID 2259946-0
    ISSN 1940-087X ; 1940-087X
    ISSN (online) 1940-087X
    ISSN 1940-087X
    DOI 10.3791/66156
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Public Health Emergency Preparedness and Response After COVID-19.

    Hoff, Christopher / Combs-Black, Karla / Sorek, Jennifer D / Elsenboss, Carina / Robinson, Misty M / Robison, Benjamin

    Health security

    2023  Volume 21, Issue S1, Page(s) S72–S78

    Language English
    Publishing date 2023-09-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2823049-8
    ISSN 2326-5108 ; 2326-5094
    ISSN (online) 2326-5108
    ISSN 2326-5094
    DOI 10.1089/hs.2023.0042
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Age-dependent accumulation of tau aggregation in

    Aquino Nunez, Wendy / Combs, Benjamin / Gamblin, T Chris / Ackley, Brian D

    Frontiers in aging

    2022  Volume 3, Page(s) 928574

    Abstract: Aging is the primary risk factor for Alzheimer's disease (AD) and related disorders (ADRDs). Tau aggregation is a hallmark of AD and other tauopathies. Even in normal aging, tau aggregation is found in brains, but in disease states, significantly more ... ...

    Abstract Aging is the primary risk factor for Alzheimer's disease (AD) and related disorders (ADRDs). Tau aggregation is a hallmark of AD and other tauopathies. Even in normal aging, tau aggregation is found in brains, but in disease states, significantly more aggregated tau is present in brain regions demonstrating synaptic degeneration and neuronal loss. It is unclear how tau aggregation and aging interact to give rise to the phenotypes observed in disease states. Most AD/ADRD animal models have focused on late stages, after significant tau aggregation has occurred. There are fewer where we can observe the early aggregation events and progression during aging. In an attempt to address this gap, we created
    Language English
    Publishing date 2022-08-19
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 3076785-4
    ISSN 2673-6217 ; 2673-6217
    ISSN (online) 2673-6217
    ISSN 2673-6217
    DOI 10.3389/fragi.2022.928574
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  4. Article ; Online: Phosphomimetics at Ser199/Ser202/Thr205 in Tau Impairs Axonal Transport in Rat Hippocampal Neurons.

    Christensen, Kyle R / Combs, Benjamin / Richards, Collin / Grabinski, Tessa / Alhadidy, Mohammed M / Kanaan, Nicholas M

    Molecular neurobiology

    2023  Volume 60, Issue 6, Page(s) 3423–3438

    Abstract: Our understanding of the biological functions of the tau protein now includes its role as a scaffolding protein involved in signaling regulation, which also has implications for tau-mediated dysfunction and degeneration in Alzheimer's disease and other ... ...

    Abstract Our understanding of the biological functions of the tau protein now includes its role as a scaffolding protein involved in signaling regulation, which also has implications for tau-mediated dysfunction and degeneration in Alzheimer's disease and other tauopathies. Recently, we found that pseudophosphorylation at sites linked to the pathology-associated AT8 phosphoepitope of tau disrupts normal fast axonal transport through a protein phosphatase 1 (PP1)-dependent pathway in squid axoplasm. Activation of the pathway and the resulting transport deficits required tau's N-terminal phosphatase-activating domain (PAD) and PP1 but the connection between tau and PP1 was not well defined. Here, we studied functional interactions between tau and PP1 isoforms and their effects on axonal transport in mammalian neurons. First, we found that wild-type tau interacted with PP1α and PP1γ primarily through its microtubule-binding repeat domain. Pseudophosphorylation of tau at S199/S202/T205 (psTau) increased PAD exposure, enhanced interactions with PP1γ, and increased active PP1γ levels in mammalian cells. Expression of psTau also significantly impaired axonal transport in primary rat hippocampal neurons. Deletion of PAD in psTau significantly reduced the interaction with PP1γ, eliminated increases of active PP1γ levels, and rescued axonal transport impairment in neurons. These data suggest that a functional consequence of phosphorylation within S199-T205 in tau, which occurs in AD and several other tauopathies, may be aberrant interaction with and activation of PP1γ and subsequent axonal transport disruption in a PAD-dependent fashion.
    MeSH term(s) Rats ; Animals ; tau Proteins/metabolism ; Axonal Transport/physiology ; Alzheimer Disease/metabolism ; Tauopathies/metabolism ; Neurons/metabolism ; Phosphorylation ; Hippocampus/metabolism ; Mammals/metabolism
    Chemical Substances tau Proteins
    Language English
    Publishing date 2023-03-02
    Publishing country United States
    Document type Journal Article
    ZDB-ID 645020-9
    ISSN 1559-1182 ; 0893-7648
    ISSN (online) 1559-1182
    ISSN 0893-7648
    DOI 10.1007/s12035-023-03281-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: THE EFFECT OF TIME AND SEX ON POST-ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION PSYCHOLOGICAL PATIENT REPORTED OUTCOME MEASURE SCORES.

    Barth, Tiffany / Bond, Colin W / MacFadden, Lisa N / Skelley, Nathan Wm / Combs, Josefine / Noonan, Benjamin C

    Journal of athletic training

    2023  

    Abstract: Context: Low scores on psychological patient reported outcomes measures (PROMs), including the anterior cruciate ligament-return to sport after injury (ACL-RSI) and injury-psychological readiness to return to sport (I-PRRS), after anterior cruciate ... ...

    Abstract Context: Low scores on psychological patient reported outcomes measures (PROMs), including the anterior cruciate ligament-return to sport after injury (ACL-RSI) and injury-psychological readiness to return to sport (I-PRRS), after anterior cruciate ligament (ACL) reconstruction (ACLR) have been associated with a maladaptive psychological response to injury and poor prognosis.
    Objective: The purpose of this study was to assess the effect of time post-ACLR and sex on ACL-RSI and I-PRRS scores and generate normative reference curves. It was hypothesized that males would demonstrate higher ACL-RSI and I-PRRS scores than females in the first 1-year post-ACLR.
    Design: Case series.
    Setting: Outpatient sports medicine and orthopedic clinic.
    Patients: 507 patients post-primary ACLR 12-to-30-years-old with 796 ACL-RSI or I-PRRS scores one or more times between 0- and 1-year post-ACLR (age at ACLR: 17.9 ± 3.0 y).
    Main outcome measures: An honest broker provided anonymous data from our institution's knee injury clinical database. Generalized additive models for location, scale, and shape and generalized least squares analyses were used to assess the effect of time post-ACLR and sex on ACL-RSI and I-PRRS scores.
    Results: ACL-RSI and I-PRRS scores increased over time post-ACLR, and males had higher scores compared to females up until approximately five months post-ACLR with scores converging thereafter.
    Conclusions: Males report higher ACL-RSI and I-PRRS scores compared to females in the initial stages of rehabilitation, but scores converge between sexes at times associated with return to play following ACLR. Normative reference curves can be used to objectively appraise patients' ACL-RSI and I-PRRS scores at any time point post-ACLR. This may lead to timely identification of patients with scores or changes in scores over time post-ACLR associated with a maladaptive psychological response to injury and a poor prognosis and optimized ACLR outcomes.
    Language English
    Publishing date 2023-11-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2070051-9
    ISSN 1938-162X ; 1062-6050
    ISSN (online) 1938-162X
    ISSN 1062-6050
    DOI 10.4085/1062-6050-0189.23
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Exposure of the Amino Terminus of Tau Is a Pathological Event in Multiple Tauopathies.

    Combs, Benjamin / Kanaan, Nicholas M

    The American journal of pathology

    2017  Volume 187, Issue 6, Page(s) 1222–1229

    Abstract: Pathological changes to the tau protein, including conformational changes and aggregation, are major hallmarks of a group of neurodegenerative disorders known as tauopathies. Among the conformational changes are alterations involving the extreme amino ... ...

    Abstract Pathological changes to the tau protein, including conformational changes and aggregation, are major hallmarks of a group of neurodegenerative disorders known as tauopathies. Among the conformational changes are alterations involving the extreme amino terminus of the protein, known as the phosphatase-activating domain (PAD). Aberrant PAD exposure induces a signaling cascade that leads to disruption of axonal transport, a critical function for neuronal survival. Conformational display of PAD is an early marker of pathological tau in Alzheimer disease (AD), but its role in other tauopathies has yet to be firmly established. We used a relatively novel N-terminal, conformation-sensitive antibody, TNT2, to determine whether misfolding in the amino terminus (ie, PAD exposure) occurs in non-AD tauopathies. We found that TNT2 specifically labeled pathological tau in post-mortem human brain tissue from Pick disease, progressive supranuclear palsy, corticobasal degeneration, and chronic traumatic encephalopathy, but did not label nonpathological, parenchymal tau. Tau13, another N-terminal antibody, was not sensitive to pathological N-terminal conformations. Tau13 did not readily distinguish between normal (ie, parenchymal tau) and pathological tau species and showed a range of effectiveness at identifying tau pathologies in the non-AD tauopathies. These findings demonstrate that the conformational display of the PAD in tau represents a common pathological event in many tauopathies.
    MeSH term(s) Aged ; Aged, 80 and over ; Antibodies, Monoclonal ; Brain/metabolism ; Female ; Humans ; Male ; Middle Aged ; Phosphorylation ; Pick Disease of the Brain/genetics ; Pick Disease of the Brain/metabolism ; Pick Disease of the Brain/pathology ; Protein Conformation ; Protein Folding ; Supranuclear Palsy, Progressive/genetics ; Supranuclear Palsy, Progressive/metabolism ; Supranuclear Palsy, Progressive/pathology ; Tauopathies/genetics ; Tauopathies/metabolism ; Tauopathies/pathology ; tau Proteins/genetics ; tau Proteins/metabolism
    Chemical Substances Antibodies, Monoclonal ; tau Proteins
    Language English
    Publishing date 2017-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2943-9
    ISSN 1525-2191 ; 0002-9440
    ISSN (online) 1525-2191
    ISSN 0002-9440
    DOI 10.1016/j.ajpath.2017.01.019
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Liquid-liquid phase separation induces pathogenic tau conformations in vitro.

    Kanaan, Nicholas M / Hamel, Chelsey / Grabinski, Tessa / Combs, Benjamin

    Nature communications

    2020  Volume 11, Issue 1, Page(s) 2809

    Abstract: Formation of membrane-less organelles via liquid-liquid phase separation is one way cells meet the biological requirement for spatiotemporal regulation of cellular components and reactions. Recently, tau, a protein known for its involvement in Alzheimer' ... ...

    Abstract Formation of membrane-less organelles via liquid-liquid phase separation is one way cells meet the biological requirement for spatiotemporal regulation of cellular components and reactions. Recently, tau, a protein known for its involvement in Alzheimer's disease and other tauopathies, was found to undergo liquid-liquid phase separation making it one of several proteins associated with neurodegenerative diseases to do so. Here, we demonstrate that tau forms dynamic liquid droplets in vitro at physiological protein levels upon molecular crowding in buffers that resemble physiological conditions. Tau droplet formation is significantly enhanced by disease-associated modifications, including the AT8 phospho-epitope and the P301L tau mutation linked to an inherited tauopathy. Moreover, tau droplet dynamics are significantly reduced by these modified forms of tau. Extended phase separation promoted a time-dependent adoption of toxic conformations and oligomerization, but not filamentous aggregation. P301L tau protein showed the greatest oligomer formation following extended phase separation. These findings suggest that phase separation of tau may facilitate the formation of non-filamentous pathogenic tau conformations.
    MeSH term(s) Animals ; Benzothiazoles/chemistry ; Brain/metabolism ; Cell Line ; Epitopes/chemistry ; Green Fluorescent Proteins/chemistry ; Humans ; Insecta ; Liquid-Liquid Extraction ; Mutation ; Protein Conformation ; Protein Domains ; Recombinant Proteins/chemistry ; Regression Analysis ; tau Proteins/chemistry
    Chemical Substances Benzothiazoles ; Epitopes ; MAPT protein, human ; Recombinant Proteins ; tau Proteins ; Green Fluorescent Proteins (147336-22-9) ; thioflavin T (2390-54-7)
    Language English
    Publishing date 2020-06-04
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-020-16580-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: Tau: A Signaling Hub Protein.

    Mueller, Rebecca L / Combs, Benjamin / Alhadidy, Mohammed M / Brady, Scott T / Morfini, Gerardo A / Kanaan, Nicholas M

    Frontiers in molecular neuroscience

    2021  Volume 14, Page(s) 647054

    Abstract: Over four decades ago, ...

    Abstract Over four decades ago,
    Language English
    Publishing date 2021-03-19
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2452967-9
    ISSN 1662-5099
    ISSN 1662-5099
    DOI 10.3389/fnmol.2021.647054
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Liquid-liquid phase separation induces pathogenic tau conformations in vitro

    Nicholas M. Kanaan / Chelsey Hamel / Tessa Grabinski / Benjamin Combs

    Nature Communications, Vol 11, Iss 1, Pp 1-

    2020  Volume 16

    Abstract: Tau plays an important role in tauopathies and undergoes liquid-liquid phase separation (LLPS). The authors show that disease-related P301L mutant and phosphomimic (S199E/S202E/T205E) tau enhance LLPS in vitro at physiological levels, and using specific ... ...

    Abstract Tau plays an important role in tauopathies and undergoes liquid-liquid phase separation (LLPS). The authors show that disease-related P301L mutant and phosphomimic (S199E/S202E/T205E) tau enhance LLPS in vitro at physiological levels, and using specific antibodies, that tau LLPS leads to pathological conformations such as N-terminal exposure and oligomeric species.
    Keywords Science ; Q
    Language English
    Publishing date 2020-06-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Liquid-liquid phase separation induces pathogenic tau conformations in vitro

    Nicholas M. Kanaan / Chelsey Hamel / Tessa Grabinski / Benjamin Combs

    Nature Communications, Vol 11, Iss 1, Pp 1-

    2020  Volume 16

    Abstract: Tau plays an important role in tauopathies and undergoes liquid-liquid phase separation (LLPS). The authors show that disease-related P301L mutant and phosphomimic (S199E/S202E/T205E) tau enhance LLPS in vitro at physiological levels, and using specific ... ...

    Abstract Tau plays an important role in tauopathies and undergoes liquid-liquid phase separation (LLPS). The authors show that disease-related P301L mutant and phosphomimic (S199E/S202E/T205E) tau enhance LLPS in vitro at physiological levels, and using specific antibodies, that tau LLPS leads to pathological conformations such as N-terminal exposure and oligomeric species.
    Keywords Science ; Q
    Language English
    Publishing date 2020-06-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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