This work was supported by the National Institute on Aging (AG039768) to MHK. We thank Drs. Thomas Sharkey and Honggao Yan for generously providing the instruments, as well Sean Weise and Yan Wu for technical assistance.

1. Preparation of Reagents
<ol>
	<li>Prepare aggregation buffer (20 mM Tris, pH 7.4, 100 mM NaCl, 1 mM EDTA). Store at RT, stable for months. Supplement 1 mM dithiothreitol (DTT) before use. 
	NOTE: a HEPES-based buffer (10 mM HEPES, pH 7.5, 0.1 mM EDTA, 5 mM DTT) also produces similar results in tau aggregation.</li>
	<li>Prepare thioflavin T or thioflavin S stock solution (3 mM, dissolved in aggregation buffer), and filter by 0.22 &#956;m sterile filter unit. Store at &#8211;20 &#176;C in a tube covered by aluminum foil, stable for months.</li>
	<li>Prepare heparin stock solution (300 &#956;M, dissolved in aggregation buffer). Store at &#8211;20 &#176;C, stable for months.</li>
	<li>Prepare dithiothreitol (DTT) stock (1 M, dissolved in water). Aliquot into 1.5 ml tubes. Store at &#8211;20 &#176;C. Before aggregation assays, thaw the 1 M solution at RT. From this 1,000x stock, prepare an aliquot of 100 mM working stock with deionized water. Leave on ice until ready.</li>
	<li>Remove tau from &#8211;80 &#176;C freezer. Thaw on ice. Adjust tau to predetermined concentration with the aggregation buffer. Spin in a microcentrifuge at 20,800 x g for 10 min at 4 &#176;C to remove pre-formed large aggregates. This pre-spinning step increases consistency in the subsequent fluorescence measurement of each batch of the protein prep. Transfer the supernatant to another tube; leave on ice until ready to assemble the aggregation reaction.</li>
</ol>
2. No-dye, Terminal Assay
NOTE: The aggregation reaction of this assay is done in the absence of the fluorescent dye. After mixing all components, the reaction is allowed to proceed to pre-determined time points. Aliquots are then taken out of the aggregation reaction and mixed with ThT or ThS for amyloid binding before fluorescence reading. The initial volume of the aggregation reaction depends on the number of time points needed. This approach may require a large amount of tau protein, but is fast, straightforward, and can be done in a fluorometer or a multi-well plate reader (see Discussion). Below is the step-by-step operation, using the ISA SPEX FluoroMax-2 compact spectrofluorometer for fluorescence quantification.
<ol>
	<li>Set up the aggregation mixture in 1.5 ml Eppendorf tubes as in Table 1. Each column represents the ingredients needed for a 100 &#956;l reaction, which is enough for one time-point measurement. Adjust the amount for the entire aggregation mix based on the time points needed for the particular experiment. Add additional 10% of each component to give room for pipetting error. The typical reaction containing heparin shown here can be replaced by arachidonic acid or aggregation buffer. Add DTT to 1 mM to the reaction mixture. If the entire reaction lasts more than one day, supplement fresh DTT everyday (1 mM) to ensure a reducing environment.</li>
	<li>Invert the tube a few times to mix. Place each reaction in a 37 &#176;C incubator or water bath. Agitation is not needed for tau aggregation.</li>
	<li>Before measuring the fluorescence, turn on the spectrofluorometer (lamp first, then computer). 
	NOTE: The xenon arc lamp that can be used right away. However, for best results allow the machine to warm up for about 10 min before reading fluorescence.</li>
	<li>Start the software on the computer.
	<ol>
		<li>Choose Real Time Display mode in Instrument Control Center, set excitation wavelength to 450 nm (slit to 2 nm) and emission wavelength to 510 nm (slit to 5 nm). Close Real Time Display mode window to return to the Instrument Control Center.</li>
		<li>Choose Constant Wavelength Analysis, press Add&#62;&#62; key in the upper frame to add wavelengths sets. Set acquisition parameters of Standard Error to 1 and Maximum Trials to 3, then click Add. Click Go! to open the Data Display window.</li>
		<li>In the Data Display window, click Start Acq to open the New Sample dialog box. Choose &#8220;unknown&#8221; for sample type.</li>
	</ol>
	</li>
	<li>To every 100 &#956;l aggregation mixture, add 98 &#181;l aggregation buffer and 2 &#181;l 3 mM thioflavin T. Pipet several times to mix.</li>
	<li>Transfer the entire mixture to a cuvette (FCA3, exterior dimension, w x l x h = 12.5 mm x 12.5 mm x 45 mm). Place the cuvette in the sample holder in the sample-compartment and close the lid. Click Run to collect the fluorescence data. Record the data.</li>
	<li>Remove the cuvette and decant the solution. Rinse the cuvette by distilled water 3 times. Dry by blowing air in and outside the cuvette.</li>
</ol>
3. With-dye, Continual Mode Assay on a SpectraMax M2 Plate Reader
NOTE: This assay differs from the previous one in that the fluorescent dye ThT or ThS is included in the aggregation reaction. This allows continuous measurement of the same set of reactions. Because of the repetitive use of the reaction, this method is better done with an automatic multi-well plate reader (as shown below the operation of SpectraMax M2). A regular fluorometer also works but the frequency of measurement of fast aggregation reactions is somewhat limited, due to the manual nature of the operation.
<ol>
	<li>Set up the aggregation mix in a 96-well plate (96-well black solid plate, well-volume 360 &#956;l, flat bottom) as in Table 2. Each column represents the ingredients needed for a 200 &#956;l reaction, which is enough for one time-point measurement. Mix well by pipetting several times. Supplement fresh 1mM DTT every day throughout the course of experiments.</li>
	<li>Incubate the 96-well plate at 37 &#176;C.</li>
	<li>At each time point before fluorescence measurement, turn on the multi-mode microplate reader and the computer. Allow sufficient time for the machine to stabilize, about 10 min.</li>
	<li>Start the software on the computer. Set temperature to 37 &#176;C and choose Fluorescence Intensity (FI-Top Read) mode, set excitation wavelength at 450 nm and emission wavelength at 510 nm.</li>
	<li>Insert the 96-well plate into the drawer and press the READ key to start measurement.</li>
	<li>After reading, remove the plate and return it back to the 37 &#176;C incubator. Copy the data and paste into an Excel spreadsheet for data analysis and plotting.</li>
</ol>
4. With-dye, Continual Mode Assay on an Compact Spectrofluorometer
<ol>
	<li>Set up the aggregation mixture in 1.5 ml Eppendorf tubes as in Table 3. Each column represents the ingredients needed for a 200 &#956;l reaction, which is enough for one time-point measurement.</li>
	<li>Invert the tube a few times to mix.</li>
	<li>Turn on the spectrofluorometer and set the software as in steps 2.3 and 2.4.</li>
	<li>Transfer the entire mixture to a cuvette. Place the cuvette in the sample holder in the sample-compartment and close the lid. Click Run to collect the fluorescence data. Record the data.</li>
	<li>Continue reading at appropriate intervals by clicking Run and recording the data. If the aggregation is to be monitored at a high frequency (e.g., every 30 or 60 sec), leave the reaction in the cuvette and in the machine until either the measurement is finished, or when there is sufficient time to swap reactions or cuvettes.</li>
	<li>Remove the cuvette and decant the solution. Rinse the cuvette by distilled water 3 times. Dry by blowing air in and outside the cuvette.</li>
</ol>

We have nothing to disclose.

This protocol demonstrates different assay conditions and instruments that detect the phosphorylation-dependent fast tau aggregation kinetics. In the terminal assay, the fluorescence dye ThT is added to a portion of the reaction removed from the master mix at each time point. Amyloid binding-induced fluorescence is then measured 26. In the second, with-dye mode, tau aggregation is carried out in the presence of ThT or ThS, rendering this type of reaction suitable for real-time automatic assessment of the growt...

Alzheimer&#8217;s disease (AD) is one of a large collection of neurodegenerative disorders known as tauopathies. The quintessential pathology underlying tauopathy is the neurofibrillary tangles, NFTs, in neurons, astrocytes and microglia 1-4. The NFT density correlates with cognitive impairment 3,5 and neuron loss 6. NFT contains primarily hyperphosphorylated tau protein (referred to as &#8220;p-tau&#8221; henceforth) that forms straight or paired helical filaments (PHF) 7,8. Tau is a microtubule associated protein thought to facilitate axonal transport that is essential for neuronal signaling and trafficking 9,10. Each tau molecule contains 2 to 3 phosphates in normal brain, but the phosphoryl content increases by several folds in tauopathy patients 11. Multiple kinases are likely to contribute to tau hyperphosphorylation including GSK3&#946; (glycogen synthase kinase 3&#946;) and CDK5 (cyclin-dependent kinase 5) 12,13, but the direct trigger for the pathological phosphorylation remains elusive 14. Abnormal phosphorylation in or near the microtubule-binding motifs dissociates tau from the microtubule 15, and causes tau mis-localization to the somatodendritic compartment, where p-tau oligomerizes into straight or paired helical filaments that can eventually polymerize into NFT inclusions. The close tie between tau hyperphosphorylation, NFT formation, and neurodegeneration led to a prevalent hypothesis that p-tau tangles elicit apoptotic and other cytotoxic responses, and thus is the underlying cause for tauopathy neurodegeneration 16,17. Drug screens and early clinical tests based on this premise have been launched 18. However, this hypothesis faces challenges 19,20. For example, SantaCruz et al. showed that cognitive functions of transgenic mice can be improved by suppressing the expression of a mutant human tau, even though NFTs continued to form from existing tau molecules 21. In a Drosophila model, NFT was shown to sequester the toxic cytosolic tau to protect the underlying neuron cells 22,23. Clearly, the pathogenesis role of NFT, if any, will greatly impact the direction of tauopathy therapeutics development.
In high concentrations, recombinant or normal brain tau protein spontaneously but slowly polymerizes into a PHF-like structure in vitro, as indicated by the binding of several &#946;-sheet preferred fluorescent dyes, electron microscopy, and light scattering spectroscopy 24-27. Adding heparin or arachidonic acid, an abundant fatty acid in human brain, drastically accelerates PHF formation in tau isoform- and inducer concentration-dependent manners 28-32. Intriguingly, hyperphosphorylated tau purified from AD brains or prepared by exhaustive in vitro phosphorylation reactions aggregates faster and more efficiently 26,33-35. These results are in excellent agreement with the pathological roles of p-tau. An in vitro system based on the aggregation of p-tau may thus serve as a powerful tool for AD drug screening.
Given the close association between tau aggregation and the progressive neurodegeneration of AD, as well as the recent failure in drug development targeting the A&#946; plaque, another key histological marker of AD 36-38, the interest in discovering drugs that control tau aggregation is rising. Indeed, several groups have already begun drug screens at different throughput, using in vitro tau aggregation reactions as the primary assay. A number of chemicals were found to exhibit inhibitory or reversal activities on tau aggregation in vitro 39-42. However, all current tau aggregation regulator screens use unmodified tau that misses the key pathological mark of phosphorylation, raising a concern for the specificity and efficacy of using these compounds in AD treatment.
One of the major hurdles of developing aggregation assays for biochemical characterization and AD drug screening is the production of sufficient quantities of the pathophysiologically relevant hyperphosphorylated tau protein. Using the Zippers-Assisted Catalysis system in which the 1N4R isoform of tau and the GSK-3&#946; kinase are co-expressed in E. coli as leucine zipper fusion proteins, we have overcome this challenge (Sui et al., submitted; see Figure 1 for the final products of tau and p-tau; also see 43 for preliminary mass spectrometry characterization of p-tau). From a panel of nine antibodies specific for different phosphorylation sites of tau, positive signals were seen in eight positions (data not shown). Below, we describe protocols and instrumentations that can differentiate the aggregation kinetic differences between unmodified tau and p-tau species. These assays were modified from published protocols that measured the increase of fluorescence of thioflavin T (ThT) or thioflavin S (ThS) upon amyloid (tau aggregates) binding 26. In the first &#8220;terminal&#8221;, no-dye approach, aggregation reactions are assembled and incubated in the absence of the amyloid dye. At different time points, an aliquot of each reaction is removed and mixed with equal volume of the ThT-containing buffer to stop aggregation and allow ThT to bind tau aggregates. Fluorescence is measured by an IAP FluoroMax-2 fluorometer. In the second &#8220;with-dye&#8221; continual monitoring assay, ThT or ThS is included in the aggregation reactions. Fluorescence can be measured continuously throughout the entire experiment manually or using a multi-plate reader. In addition, we describe an assay that uses a near-physiological concentration of tau and p-tau for aggregation in the continual measurement mode. The effect of phosphorylation remains readily detectable. Below, we will describe step-by-step operation procedures, and show representative results of these assays. Discussion of some of the pros and cons of each approach, as well as potential drug screening applications will follow.
At a high concentration, tau aggregates into amyloid-like structures spontaneously. However, in the laboratory, tau fibrillization is typically accelerated by such inducers as heparin (average molecular weight, 6,000 g/mol) and arachidonic acid. Examples shown herein include 30 &#181;M heparin. The formation of tau amyloid aggregates is monitored by the fluorescence resulting from amyloid binding by thioflavin T (ThT) or thioflavin S (ThS). Upon binding to tau aggregates, ThT exhibits a red shift in fluorescence (excitation: 450 nm; peak emission: 485 nm). ThS, on the other hand, has weak emission at 510 nm (excitation at 450 nm) before amyloid binding, but this fluorescence increases significantly in the presence of an amyloid protein such as the aggregated tau 44. Both dyes work well in detecting tau and p-tau aggregation. Because of the strong and relatively broad emission peak of ThT (see Figure 2), there is only 30% reduction in the fluorescence unit at 510 nm. For convenience, we use the same combination of excitation/emission wavelengths (i.e., 450 nm/510 nm) to monitor tau aggregation when using either dye.
Tau aggregation can be done in the presence or absence of the dye, depending on the purpose of the assay and the availability of tau protein. Both modes of reactions are shown below. In addition, we demonstrate the operation of two different instruments &#8211; a single-sample fluorometer (ISA-SPEX FluoroMax-2) and a multi-plate reader (SpectraMax M2). Readers should be able to adapt these protocols to suit their specific needs and instrument availability.

<table><tbody><tr><td>Trizma&amp;nbsp;base</td><td>Sigma</td><td>T1503</td><td></td></tr><tr><td>NaCl</td><td>Macron Fine Chemicals</td><td>MAL-7581-06</td><td></td></tr><tr><td>Ethylenediaminetetraacetic Acid (EDTA)</td><td>Invitrogen</td><td>15576-028</td><td></td></tr><tr><td>Thioflavin T</td><td>Sigma</td><td>T3516</td><td>Stored in dark</td></tr><tr><td>Thioflavin S</td><td>Sigma</td><td>T1892</td><td>Stored in dark</td></tr><tr><td>heparin</td><td>Sigma</td><td>H3393</td><td></td></tr><tr><td>DL-Dithiothreitol (DTT)</td><td>Sigma</td><td>D9779</td><td>Stored at 4 &amp;deg;C</td></tr><tr><td>96-well plate</td><td>Corning</td><td>3917</td><td></td></tr><tr><td>ISA SPEX FluoroMax-2</td><td>Horiba</td><td></td><td></td></tr><tr><td>SpectraMax M2 Multi-Mode Microlate Reader</td><td>Molecular Devices</td><td></td><td></td></tr><tr><td>Mouse Anti-Tau Monoclonal Antibody</td><td>R&amp;amp;D Systems</td><td>MAB3494</td><td>Stored at &amp;ndash;80 &amp;deg;C</td></tr></tbody></table>

in vitro aggregation assays using hyperphosphorylated tau protein

Alzheimer's disease is one of a large group of neurodegenerative disorders known as tauopathies that are manifested by the neuronal deposits of hyperphosphorylated tau protein in the form of neurofibrillary tangles (NFTs). The density of NFT correlates well with cognitive impairment and other neurodegenerative symptoms, thus prompting the endeavor of developing tau aggregation-based therapeutics. Thus far, however, tau aggregation assays use recombinant or synthetic tau that is devoid of the pathology-related phosphorylation marks. Here we describe two assays using recombinant, hyperphosphorylated tau as the subject. These assays can be scaled up for high-throughput screens for compounds that can modulate the kinetics or stability of hyperphosphorylated tau aggregates. Novel therapeutics for Alzheimer's disease and other tauopathies can potentially be discovered using hyperphosphorylated tau isoforms.

Using recombinant tau and p-tau (Figure 1), we established two different protocols to compare the kinetics of aggregation of tau and p-tau, taking advantage of the strong fluorescence emission of ThT and ThS upon binding to amyloidal protein aggregates, including tau and p-tau (Figure 2). With or without the fluorescent dye in the aggregation reaction, we observed consistent enhancement of tau aggregation by hyperphosphorylation (Figures 3&#8211;5). This stimulation is i...

Watch this Scientific Journal Video about In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein at JoVE.com

In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

Unmodified and hyperphosphorylated tau proteins were used in two in vitro aggregation assays to reveal the hyperphosphorylation-dependent fast aggregation kinetics. These assays pave the way for future screens for compounds that can modulate the propensity of hyperphosphorylated tau to form fibrils that underlie the progression of Alzheimer&#8217;s disease.

In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

Alzheimer's disease is one of a large group of neurodegenerative disorders known as tauopathies that are manifested by the neuronal deposits of ...

in-vitro-aggregation-assays-using-hyperphosphorylated-tau-protein

Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

18.3K Views.  Michigan State University. Unmodified and hyperphosphorylated tau proteins were used in two in vitro aggregation assays to reveal the hyperphosphorylation-dependent fast aggregation kinetics. These assays pave the way for future screens for compounds that can modulate the propensity of hyperphosphorylated tau to form fibrils that underlie the progression of Alzheimer’s disease.

Video: In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

Nuclear Magnetic Resonance Spectroscopy for the Identification of Multiple Phosphorylations of Intrinsically Disordered Proteins

Aggregates of the neuronal Tau protein are found inside neurons of Alzheimer's disease patients. Development of the disease is accompanied by increased, abnormal phosphorylation of Tau. In the course of the molecular investigation of Tau functions and dysfunctions in the disease, nuclear magnetic resonance (NMR) spectroscopy is used to identify the multiple phosphorylations of Tau. We present here detailed protocols of recombinant production of Tau in bacteria, with isotopic enrichment for NMR studies. Purification steps that take advantage of Tau's heat stability and high isoelectric point are described. The protocol for in vitro phosphorylation of Tau by recombinant activated ERK2 allows for generating multiple phosphorylations. The protein sample is ready for data acquisition at the issue of these steps. The parameter setup to start recording on the spectrometer is considered next. Finally, the strategy to identify phosphorylation sites of modified Tau, based on NMR data, is explained. The benefit of this methodology compared to other techniques used to identify phosphorylation sites, such as immuno-detection or mass spectrometry (MS), is discussed.

We describe here a method to identify multiple phosphorylations of an intrinsically disordered protein by Nuclear Magnetic Resonance Spectroscopy (NMR), using Tau protein as a case study. Recombinant Tau is isotopically enriched and modified in vitro by a kinase prior to data acquisition and analysis.

Aggregates of the neuronal Tau protein are found inside neurons of Alzheimer's disease patients. Development of the disease is accompanied by increased, ...

Biochemistry

Assay for Phosphorylation and Microtubule Binding Along with Localization of Tau Protein in Colorectal Cancer Cells

The microtubule-associated protein tau is a neuronal protein that localizes mostly in axons. Generally tau is essential for normal neuronal functioning because it is involved in microtubule assembly and stabilization. Besides neurons, tau is expressed in human breast, prostate, gastric, colorectal, and pancreatic cancers where it shows nearly similar structure and exerts similar functions as the neuronal tau. The amount of tau and its phosphorylation can change its function as a stabilizer of microtubules, and lead to the development of paired helical filaments in different neurodegenerative disorders, such as Alzheimer&#39;s disease. Determining the phosphorylation state of tau and its microtubule-binding characteristics is important. In addition, examining the intracellular localization of tau is important in different diseases. This manuscript details standard protocols for measuring tau phosphorylation and tau binding to microtubules in colorectal cancer cells with or without curcumin and LiCl treatment. These treatments can be used to stop cancer cell proliferation and development. Intracellular localization of tau is examined by using immunohistochemistry and confocal microscopy while using low amounts of antibodies. These assays can be used repetitively for screening compounds that affect tau hyperphosphorylation or microtubule binding. Novel therapeutics used for different tauopathies or related anticancer agents can potentially be characterized using these protocols.

This manuscript describes standard protocols for measuring tau hyperphosphorylation, measuring tau binding to microtubules, and localization of intracellular tau following drug treatments. These protocols can be used repetitively for screening drugs or other compounds that target tau hyperphosphorylation or microtubule binding.

The microtubule-associated protein tau is a neuronal protein that localizes mostly in axons. Generally tau is essential for normal neuronal functioning ...

Sensitive Detection of Proteopathic Seeding Activity with FRET Flow Cytometry

Increasing evidence supports transcellular propagation of toxic protein aggregates, or proteopathic seeds, as a mechanism for the initiation and progression of pathology in several neurodegenerative diseases, including Alzheimer's disease and the related tauopathies. The potentially critical role of tau seeds in disease progression strongly supports the need for a sensitive assay that readily detects seeding activity in biological samples. 
By combining the specificity of fluorescence resonance energy transfer (FRET), the sensitivity of flow cytometry, and the stability of a monoclonal cell line, an ultra-sensitive seeding assay has been engineered and is compatible with seed detection from recombinant or biological samples, including human and mouse brain homogenates. The assay employs monoclonal HEK 293T cells that stably express the aggregation-prone repeat domain (RD) of tau harboring the disease-associated P301S mutation fused to either CFP or YFP, which produce a FRET signal upon protein aggregation. The uptake of proteopathic tau seeds (but not other proteins) into the biosensor cells stimulates aggregation of RD-CFP and RD-YFP, and flow cytometry sensitively and quantitatively monitors this aggregation-induced FRET. The assay detects femtomolar concentrations (monomer equivalent) of recombinant tau seeds, has a dynamic range spanning three orders of magnitude, and is compatible with brain homogenates from tauopathy transgenic mice and human tauopathy subjects. With slight modifications, the assay can also detect seeding activity of other proteopathic seeds, such as &#945;-synuclein, and is also compatible with primary neuronal cultures. The ease, sensitivity, and broad applicability of FRET flow cytometry makes it useful to study a wide range of protein aggregation disorders.

Cell-to-cell transfer of protein aggregates, or proteopathic seeds, may underlie the progression of pathology in neurodegenerative diseases. Here, a novel FRET flow cytometry assay is described that enables specific and sensitive detection of seeding activity from recombinant or biological samples.

Increasing evidence supports transcellular propagation of toxic protein aggregates, or proteopathic seeds, as a mechanism for the initiation and ...

Bioengineering

In Vitro Assay for Studying the Aggregation of Tau Protein and Drug Screening

Aggregation of tau protein and formation of paired helical filaments is a hallmark of Alzheimer&#39;s disease and other tauopathies. Compared to other proteins associated with neurodegenerative diseases, the reported in vitro aggregation kinetics for tau protein are less consistent presenting a relatively high variability. Here we describe the development of an in vitro aggregation assay that mimics the expected steps associated with tau misfolding and aggregation in vivo. The assay uses the longest tau isoform (huTau441) which contains both N-terminal acidic inserts as well as four microtubule binding domains (MBD). The in vitro aggregation is triggered by addition of heparin and followed continuously by thioflavin T fluorescence in a 96 well microplate format. The tau aggregation assay is highly reproducible between different wells, experimental runs and batches of the protein. The aggregation leads to tau PHF-like morphology which is very efficient in seeding the formation of de novo fibrillar structures. In addition to its application in studying the mechanism of tau misfolding and aggregation, the current assay is a robust tool for screening drugs that could interfere with the pathogenesis of tau.

In Vitro Assay for Studying the Aggregation of Tau Protein and Drug Screening

The tau aggregation assay described in this manuscript mimics the anticipated features of in vivo tau misfolding and aggregation.

Aggregation of tau protein and formation of paired helical filaments is a hallmark of Alzheimer&#39;s disease and other tauopathies. Compared to other ...

Neuroscience

Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing neuronal dysfunction which eventually leads to cognitive decline. Hyperphosphorylated tau aggregates in the neuron are believed to cause most of the pathology associated with AD. These aggregates are assumed to be released into the extracellular compartment and taken up by adjacent healthy neurons where they induce further tau aggregation. This &#34;prion-like&#34; spreading can be interrupted by antibodies capable of binding and &#34;neutralizing&#34; extracellular tau aggregates as shown in preclinical mouse models of AD. One of the proposed mechanisms by which therapeutic antibodies reduce pathology is antibody-mediated uptake and clearance of pathological aggregated forms of tau by microglia. Here, we describe a quantitative cell-based assay to assess tau uptake by microglia. This assay uses the mouse microglial cell line BV-2, allows for high specificity, low variability and medium throughput. Data generated with this assay can contribute to a better characterization of anti-tau antibody effector functions.

Here we describe a cell-based assay to quantitatively assess tau uptake by microglia with the aim of creating an investigational tool to better characterize the mechanisms of action of anti-tau antibodies.

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing ...

An In Vitro Model for Studying Tau Aggregation Using Lentiviral-mediated Transduction of Human Neurons

Aberrant aggregation of the protein tau is pathogenically involved in a number of neurodegenerative diseases, including Alzheimer&#8217;s disease (AD). Although mouse models of tauopathy have provided a valuable resource for investigating the neurotoxic mechanisms of aggregated tau, it is becoming increasingly apparent that, due to interspecies differences in neurophysiology, the mouse brain is unsuitable for modeling the human condition. Advances in cell culture methods have made human neuronal cultures accessible for experimental use in vitro and have aided in the development of neurotherapeutics. However, despite the adaptation of human neuronal cell cultures, in vitro models of human tauopathy are not yet widely available. This protocol describes a cellular model of tau aggregation in which human neurons are transduced with lentiviral-derived vectors that code for pathogenically mutated tau fused to a yellow fluorescent protein (YFP) reporter. Transduced cultures produce tau aggregates that stain positively for thioflavin and display markers of neurotoxicity, such as decreased axonal length and increased lysosomal volume. This procedure may be a useful and cost-effective model for studying human tauopathies.

This protocol details a procedure in which human neuronal cultures are transduced with lentiviral constructs coding for mutant human tau. Transduced cultures display tau aggregates and associated pathologies.

Aberrant aggregation of the protein tau is pathogenically involved in a number of neurodegenerative diseases, including Alzheimer&#8217;s disease (AD). ...

Nuclear Magnetic Resonance Spectroscopy to Identify Multiple Phosphorylations in Proteins

Source: Danis, C. et. al., <a href="https://appjove.unicartagenaproxy.elogim.com/v/55001">Nuclear Magnetic Resonance Spectroscopy for the Identification of Multiple Phosphorylations of Intrinsically Disordered Proteins.</a>&#160;J. Vis. Exp.&#160; (2016).
This video demonstrates the use of nuclear magnetic resonance spectroscopy (NMR) techniques to identify multiple phosphorylations in a protein. The phosphorylation of a protein at specific amino acid causes the deshielding of the neighboring amide hydrogen, which generates the spectral difference.

Spektroskopia magnetycznego rezonansu jądrowego w celu identyfikacji wielokrotnych fosforylacji białek

Source: Danis, C. et. al., Nuclear Magnetic Resonance Spectroscopy for the Identification of Multiple Phosphorylations of Intrinsically Disordered ...

JoVE Encyclopedia of Experiments

Biological Techniques

Spectroscopy Techniques

A Cell-Based Assay to Assess the Tau Protein Uptake by Microglia

Source: De Marco, D. et al., <a href="https://appjove.unicartagenaproxy.elogim.com/v/58576">Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia.</a>&#160;J. Vis. Exp. (2018)
This video showcases a cell-based assay quantifying Tau uptake by murine microglia using pH-sensitive fluorescent-labeled Tau aggregates, analyzed via fluorescence-activated cell sorting for a quantitative assessment.

Test komórkowy do oceny wychwytu białka tau przez mikroglej

1. BV-2 Microglia Cells Culture
NOTE: Handle BV-2 cells under Biosafety Level 2 containment. The BV-2 cell line produces an enveloped recombinant ...

Immunology

Antibody-Based Technologies

Characterization and Functional Analysis

Phosphatase Assay in CRC Cells: A Method to Examine the Phosphorylation Status of Tau Protein in Colorectal Cancer Cells

Source: Huda, M. N., et al. <a href="https://jove.unicartagenaproxy.elogim.com/v/55932"> Assay for Phosphorylation and Microtubule Binding Along with Localization of Tau Protein in Colorectal Cancer Cells.</a> J. Vis. Exp. (2017)
This video describes a protocol for assessing the phosphorylation status of tau protein by a phosphatase assay in colorectal cancer cells. Phosphatase enzyme acts on the phosphate groups present on the tau protein, increasing the mobility of tau protein on SDS PAGE gel compared to the untreated tau protein samples.

Test fosfatazy w komórkach CRC: metoda badania stanu fosforylacji białka Tau w komórkach raka jelita grubego

Source: Huda, M. N., et al.  Assay for Phosphorylation and Microtubule Binding Along with Localization of Tau Protein in Colorectal Cancer Cells. J. Vis. ...

Cancer Research

Colorectal Cancer

Assays & techniques

Lentiviral-Mediated Transduction of Human Neurons for Tau Protein Aggregation Analysis

Source: Aulston, B., et al. <a href="https://appjove.unicartagenaproxy.elogim.com/v/59433">An In Vitro Model for Studying Tau Aggregation Using Lentiviral-mediated Transduction of Human Neurons.</a>&#160;
This video demonstrates the process of transducing human neuronal cells with a lentivirus encoding a mutant human tau protein tagged with yellow fluorescent protein (YFP) to study protein aggregation. It outlines the steps from viral entry to mutant tau expression, culminating in the formation of visible cytoplasmic tau aggregates in the neurons.

Source: Aulston, B., et al. An In Vitro Model for Studying Tau Aggregation Using Lentiviral-mediated Transduction of Human Neurons.&#160;
This video ...

In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein

Podsumowanie

Przeglądaj więcej filmów

Rozdziały w tym wideo

Nuclear Magnetic Resonance Spectroscopy for the Identification of Multiple Phosphorylations of Intrinsically Disordered Proteins

Assay for Phosphorylation and Microtubule Binding Along with Localization of Tau Protein in Colorectal Cancer Cells

Sensitive Detection of Proteopathic Seeding Activity with FRET Flow Cytometry

In Vitro Assay for Studying the Aggregation of Tau Protein and Drug Screening

Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia

An In Vitro Model for Studying Tau Aggregation Using Lentiviral-mediated Transduction of Human Neurons

Spektroskopia magnetycznego rezonansu jądrowego w celu identyfikacji wielokrotnych fosforylacji białek

Test komórkowy do oceny wychwytu białka tau przez mikroglej

Test fosfatazy w komórkach CRC: metoda badania stanu fosforylacji białka Tau w komórkach raka jelita grubego

Lentiviral-Mediated Transduction of Human Neurons for Tau Protein Aggregation Analysis