Name: a11-positive &#946;-amyloid oligomer preparation and assessment using dot blotting analysis
Uploaded: 2018-05-22T13:30:00
Description: Watch this Scientific Journal Video about A11-positive Î²-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis at JoVE.com

This work was supported by grants from the National Natural Science Foundation of China (U1503223, 81673407, 21475131), the Applied Research Project on Nonprofit Technology of Zhejiang Province (2016C37110), the Ningbo International Science and Technology Cooperation Project (2014D10019), the Ningbo Municipal Innovation Team of Life Science and Health (2015C110026), the Ningbo Sci &amp; Tech Project for Common Wealth (2017C50042), the Li Dak Sum Yip Yio Chin Kenneth Li Marine Biopharmaceutical Development Fund, and the K. C. Wong Magna Fund at Ningbo University.

1. Solution Preparation
NOTE: See Table of Materials for reagent sources.
<ol>
	<li>Prepare a 5% bovine serum albumin (BSA) solution by adding 5 g of BSA to 100 mL of double-distilled water. Mix them completely by vortexing them. Store the solution at 4 &#176;C for up to 1 month.</li>
	<li>Prepare an anti-oligomer antibody A11 solution (1:1,000) by adding 10 &#181;L of antibody stock solution to 10 mL of the 5% BSA solution. Mix them completely by vortexing them. Store the s...

<ol>
	<li>Lauren, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+prion+protein+as+a+therapeutic+target+in+Alzheimer's+disease.">Cellular prion protein as a therapeutic target in Alzheimer's disease.</a> Journal of Alzheimer's Disease. 38 (2), 227-244 (2014).</li><li>De Maio, A., Rivera, I., Cauvi, D. M., Arispe, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+amyloid+peptide+oligomerization+and+toxicity+by+extracellular+Hsp70.">Modulation of amyloid peptide oligomerization and toxicity by extracellular Hsp70.</a> Biophysical Journal. 112 (3), 444 (2017).</li><li>Di Scala, C., Chahinian, H., Yahi, N., Garmy, N., Fantini, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interaction+of+Alzheimer's+beta-amyloid+peptides+with+cholesterol:+mechanistic+insights+into+amyloid+pore+formation.">Interaction of Alzheimer's beta-amyloid peptides with cholesterol: mechanistic insights into amyloid pore formation.</a> Biochemistry. 53 (28), 4489-4502 (2014).</li><li>Xiang, S. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fucoxanthin+inhibits+beta-amyloid+assembly+and+attenuates+beta-amyloid+oligomer-induced+cognitive+impairments.">Fucoxanthin inhibits beta-amyloid assembly and attenuates beta-amyloid oligomer-induced cognitive impairments.</a> Journal of Agricultural and Food Chemistry. 65 (20), 4092-4102 (2017).</li><li>Chang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protection+against+beta-amyloid-induced+synaptic+and+memory+impairments+via+altering+beta-amyloid+assembly+by+bis(heptyl)-cognitin.">Protection against beta-amyloid-induced synaptic and memory impairments via altering beta-amyloid assembly by bis(heptyl)-cognitin.</a> Scientific Reports. 5, 10256 (2015).</li><li>Yam, G. H. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+amyloid+aggregate+forming+ability+of+TGFBI+mutants+that+cause+corneal+dystrophies.">In vitro amyloid aggregate forming ability of TGFBI mutants that cause corneal dystrophies.</a> Investigative Ophthalmology &amp; Visual Science. 53 (9), 5890-5898 (2012).</li><li>Tomaselli, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+alpha-to-beta+conformational+transition+of+Alzheimer's+A+beta-(1-42)+peptide+in+aqueous+media+is+reversible:+A+step+by+step+conformational+analysis+suggests+the+location+of+beta+conformation+seeding.">The alpha-to-beta conformational transition of Alzheimer's A beta-(1-42) peptide in aqueous media is reversible: A step by step conformational analysis suggests the location of beta conformation seeding.</a> ChemBioChem. 7 (2), 257-267 (2006).</li><li>Shigemitsu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+magnetic+resonance+evidence+for+the+dimer+formation+of+beta+amyloid+peptide+1-42+in+1,1,1,3,3,3-hexafluoro-2-propanol.">Nuclear magnetic resonance evidence for the dimer formation of beta amyloid peptide 1-42 in 1,1,1,3,3,3-hexafluoro-2-propanol.</a> Analytical Biochemistry. 498, 59-67 (2016).</li><li>Khan, M. V., Rabbani, G., Ahmad, E., Khan, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluoroalcohols-induced+modulation+and+amyloid+formation+in+conalbumin.">Fluoroalcohols-induced modulation and amyloid formation in conalbumin.</a> International Journal of Biological Macromolecules. 70, 606-614 (2014).</li><li>Fang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=5-hydroxycyclopenicillone,+a+new+beta-amyloid+fibrillization+inhibitor+from+a+sponge-derived+fungus+trichoderma+sp+HPQJ-34.">5-hydroxycyclopenicillone, a new beta-amyloid fibrillization inhibitor from a sponge-derived fungus trichoderma sp HPQJ-34.</a> Marine Drugs. 15 (8), 260 (2017).</li><li>Shiao, Y. J., Su, M. H., Lin, H. C., Wu, C. 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In this protocol, we have reported a method to prepare samples containing A&#946;1-42 oligomer, and to analyze the amounts of A11-positive A&#946;1-42 oligomer by a dot blotting analysis. Although our methods for the preparation of A&#946;1-42 oligomer-rich samples are quite simple, reliable, and reproducible, there are still some points to be noticed. Firstly, HFIP is used to dissolve the synthetic A&#946;1-42 peptide. An aggregated A&#946;1-42 peptide can disassemb...

Alzheimer&#39;s disease (AD) is one of the most important neurodegenerative diseases affecting elderly people worldwide1. It is widely accepted that the abnormal aggregation of &#946;-amyloid (A&#946;) may be the leading pathological factor of AD. A&#946; aggregates are the main components of the senile plaques, one of the biological markers in the brains of AD patients. Moreover, A&#946; aggregates, including oligomers in particular, produce potent neurotoxicity, which might be the cause of neuronal death as AD progresses. Therefore, the inhibition of A&#946; oligomer formation might prevent neurodegeneration, and A&#946; oligomer inhibitors could be developed as disease-modifying treatments of AD. Many studies have used a synthetic A&#946; peptide to form oligomers in vitro, explore morphologies and structures of artificial A&#946; oligomers, and investigate the inhibitors of A&#946; oligomer using in vitro models2,3,4. However, different in vitro formation protocols of A&#946; oligomer could lead to oligomer with different morphological characteristics, which might cause the incomparable results among different research groups. Therefore, a standard formation protocol for A&#946; oligomer is urgently needed.
Until now, not many methods have been reported to directly detect A&#946; oligomers. Transmission electronic microscopy (TEM), non-denaturing gel electrophoresis, enzyme-linked immunosorbent assay (ELISA), and dot blotting analysis can be used to examine the amount and/or morphology of A&#946; oligomer in vitro5,6. For example, the morphology and structure of A&#946; oligomer can be observed in TEM. The relative amounts and molecular size of A&#946; aggregations could be measured by non-denaturing gel electrophoresis. ELISA could be used to determine A&#946; oligomer in serum, plasma, and extracts from brain tissue. Lastly, dot blotting analysis, a technique used for detecting, analyzing, and identifying proteins, could be used to evaluate the relative concentration of A&#946; oligomer in different samples with the help of oligomer-specific and A&#946;-specific antibodies. Moreover, a dot blotting assay offers significant time savings, as gel electrophoresis and the blotting procedures for gels are not required. Therefore, this assay is normally used to screen potential A&#946; oligomer inhibitors. The overall goal of this protocol is to describe a relatively simple, reliable, and reproducible method to prepare an A&#946;1-42 oligomer-rich sample, to analyze the amounts of A&#946;1-42 oligomer by dot blotting analysis, and to screen A&#946; oligomer inhibitors using semi-quantitative experimental results.

<table border="0" cellpadding="0" cellspacing="0" style="width:1159px;" width="1158">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:371px;">A11 (ab126892 Rb pAb to Amyloid Oligomers)</td>
			<td style="width:219px;">Abcam</td>
			<td style="width:211px;">GR91739-58</td>
			<td style="width:359px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6E10 (beta-Amyloid Rabbit Ab)</td>
			<td>Cell&#160;Signalling Technology</td>
			<td>2454S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">OC (Anti-Amyloid Fibrils OC Antibody)</td>
			<td>Millipore</td>
			<td>AB2286</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Horseradish Peroxidase (HRP) Marker Goat anti rabbit IgG (H+L)&#160;</td>
			<td>Beyotime</td>
			<td>A0208</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">A&#946;1-42</td>
			<td>GL Biochem</td>
			<td>52487</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1,1,1,3,3,3-Hexafiuoro-2-propanol</td>
			<td>Aladdin</td>
			<td>I1523078</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Curcumin</td>
			<td>Sigma</td>
			<td>C1386</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Albumin Bovine V</td>
			<td>Solarbio</td>
			<td>A8020</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium chloride</td>
			<td>Sangon Biotech</td>
			<td>D920BA0003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium dodecyl sulfate</td>
			<td>SCR</td>
			<td>30166428</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TRIS</td>
			<td>Solarbio</td>
			<td>T8060</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glycine</td>
			<td>Solarbio</td>
			<td>G8200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#160;Dimethyl sulfoxide</td>
			<td>Solarbio</td>
			<td>D8370</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">5&#215;nondenaturing gel PAGE Protein Marker</td>
			<td>Beyotime</td>
			<td>P0016</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Genshare CFAS anyKD PAGE</td>
			<td>Genshare</td>
			<td>JC-PE022</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pure Nitrocellulose Blotting Membrane</td>
			<td>Pall Corporation</td>
			<td>T50189</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Methanol</td>
			<td>SCR</td>
			<td>10014118</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ethanol</td>
			<td>SCR</td>
			<td>10009218</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Super low range&#160;protein Marker</td>
			<td>Solarbio</td>
			<td>PR1300</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Transfer Membranes</td>
			<td>Immobilon-PSQ</td>
			<td>ISEQ00010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BeyoECL Star</td>
			<td>Beyotime</td>
			<td>P0018A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Commassie Blue Fast staining solution</td>
			<td>Beyotime</td>
			<td>P0017</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">All - automatic chemiluminescence imaging system</td>
			<td>Tanon</td>
			<td>Tanon 5200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Image J</td>
			<td>National Institutes of Health</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Image processing software</td>
			<td>Adobe</td>
			<td>Photoshop CS6</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Magnetic agitator</td>
			<td>Shanghai Huxi</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

a11-positive &#946;-amyloid oligomer preparation and assessment using dot blotting analysis

&#946;-amyloid (A&#946;) is a hydrophobic peptide with an intrinsic tendency to self-assemble into aggregates. Among various aggregates, A&#946; oligomer is widely accepted as the leading neurotoxin in the progress of Alzheimer&#39;s disease (AD) and is considered to be the crucial event in the pathogenesis of AD. Therefore, A&#946; oligomer inhibitors might prevent neurodegeneration and have the potential to be developed as disease-modifying treatments of AD. However, different formation protocols of A&#946; oligomer might lead to oligomers with different characteristics. Moreover, there are not many methods to effectively screen A&#946;1-42 oligomer inhibitors. An A11 antibody can react with a subset of toxic A&#946;1-42 oligomer with anti-parallel &#946;-sheet structures. In this protocol, we describe how to prepare an A11-positive A&#946;1-42 oligomer-rich sample from a synthetic A&#946;1-42 peptide in vitro and to evaluate relative amounts of A11-positive A&#946;1-42 oligomer in samples by a dot blotting analysis using A11 and A&#946;1-42-specific 6E10 antibodies. Using this protocol, inhibitors of A11-positive A&#946;1-42 oligomer can also be screened from semi-quantitative experimental results.

To investigate whether an A&#946;1-42 monomer can form an A&#946;1-42 oligomer after preparation, TEM analysis was used. No visible aggregates were observed in the HFIP-dissolved A&#946;1-42 monomer sample (Figure 1A). Moreover, mainly globular aggregates with a diameter of around 10 - 80 nm were observed in the A&#946;1-42 sample after 48 h of shaking, suggesting that A&#946;1-42 forms o...

Watch this Scientific Journal Video about A11-positive Î²-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis at JoVE.com

A11-positive &#946;-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis

This protocol describes how to prepare A&#946; oligomers from a synthetic peptide in vitro and to evaluate relative amounts of A&#946; oligomer by a dot blotting analysis.

&#946;-amyloid (A&#946;) is a hydrophobic peptide with an intrinsic tendency to self-assemble into aggregates. Among various aggregates, A&#946; oligomer ...

This method can help answer key questions in the neuropharmacological field. The main advantage of this technique is that it's simple, reliable, and reproducible to form beta-amyloid oligomer. We show demonstration of this method is critical as steps for preparing beta oligomer are difficult to learn.First, adjust the concentration of A-beta monomer solution to 0.25 milligrams per milliliter by adding 900 microliters of double-distilled water to the tube. Then continue evaporating the monomer solution with high purity nitrogen gas until the volume reaches about 850 microliters with a concentration of about 0.29 milligrams per milliliter. The presence of HR5P affects the formation of A-beta oligomer.Therefore, evaporating as much as possible is a critical step of this procedure. Next, use double-distilled water to dilute the curcumin stock solution to prepare a working solution of 0.2 and two micromolar. Maintain a ratio of one-to-one and mix the A-beta solution with curcumin to achieve the final concentration of curcumin at 0.1 and one micromolar.Then, leave the solution on a magnetic agitator. Attach a plastic divider box to the magnetic agitator. Position two magnetic stir bars at the two corners of the box, then place the tubes with the samples in the center of the box.Continue shaking the box at room temperature for 48 hours at 60 revolutions per minute, then centrifuge the tube at 18, 000 times G for 15 minutes at four degrees celsius. After centrifugation, collect the supernatant. For dot blotting analysis, take a nitrocellulose membrane and cut it into one-centimeter wide strips, then place two microliters of the sample evenly on the strips one and two with each point interval at 0.5 centimeters.When squirting the sample on membrane, it's necessary to spread evenly and the different droplets are controlled so that the different samples are not linked together. Next, incubate the strips at room temperature for five minutes for the droplets to dry out. After five minutes, incubate the strips with 5%bovine serum albumin for 30 minutes at room temperature.Once the incubation is over, wash the strips with TBST buffer for five minutes. Aspirate the buffer after the wash is done, then incubate strip one with anti-oligomer antibody A11 and strip two with anti-A-beta antibody 6E10 solution for an hour. After one hour, wash the strips with TBST for five minutes each three times, then aspirate the buffer and incubate the strips with secondary antibody solution for 40 minutes.After the secondary antibody incubation, again wash the strips with TBST for five minutes each three times. Then, add about 300 microliters of mixed ECL fluid to the surface of the moist strips, then expose the strips in an automatic chemiluminescence imaging system. TEM studies show the absence of any visible aggregates in the HFIP-dissolved A-beta monomer solution, however after 48 hours of incubation, the same monomer form oligomers, which are mainly globular aggregates with a diameter of 10 to 80 nanometers.On subjecting the A-beta monomer and oligomer-rich samples to dot blot analysis, it shows the presence of A11 positive A-beta oligomers in A-beta oligomer-rich samples. Interestingly, A-beta 6E10 positive A-beta peptides are present in both the A-beta monomer and oligomer-rich samples. Next, semi-quantitative analysis is also done to express the specific antibody-positive A-beta monomer and oligomer-rich samples as a percentage of control.A11 positive A-beta peptides are significantly higher in A-beta oligomer-rich samples in comparison to the monomers. On the contrary, A-beta 6E10 positive A-beta peptide is present in both the monomer and oligomer-rich samples. In fact, A-beta oligomers are also co-incubated with curcumin and A-beta oligomer inhibitor.Curcumin leads to significant reduction in the relative amount of A11 positive A-beta oligomer with decreased A11 staining in the curcumin co-incubated A-beta oligomer samples. However, varying concentrations of curcumin do not affect the number of A-beta peptides in the 6E10 positive monomer and oligomer-rich samples when compared to A11 positive samples. Once mastered, this technique can be done in several hours if it performed properly.After its development, this technique paved the way for researchers to explore drug candidates for neurodegenerative disorders such as Alzheimer's Disease. After watching this video, you should have a good understanding of how to prepare A-beta oligomer and to evaluate its amount.

a11-positive-amyloid-oligomer-preparation-assessment-using-dot

Research

JoVE Journal

Biochemistry

SorLA and CLC:CLF-1-dependent Downregulation of CNTFR&#945; as Demonstrated by Western Blotting, Inhibition of Lysosomal Enzymes, and Immunocytochemistry

The heterodimeric cytokine Cardiotrophin-like Cytokine:Cytokine-like Factor-1 (CLC:CLF-1) targets the glycosylphosphatidylinositol (GPI)-anchored CNTFR&#945; to form a trimeric complex that subsequently recruits glycoprotein 130/Leukemia Inhibitory Factor Receptor-&#946; (gp130/LIFR&#946;) for signaling. Both CLC and CNTFR&#945; are necessary for signaling but so far CLF-1 has only been known as a putative facilitator of CLC secretion. However, it has recently been shown that CLF-1 contains three binding sites: one for CLC; one for CNTFR&#945; (that may promote assembly of the trimeric complex); and one for the endocytic receptor sorLA. The latter site provides high affinity binding of CLF-1, CLC:CLF-1, as well as the trimeric (CLC:CLF-1:CNTFR&#945;) complex to sorLA, and in sorLA-expressing cells the soluble ligands CLF-1 and CLC:CLF-1 are rapidly taken up and internalized. In cells co-expressing CNTFR&#945; and sorLA, CNTFR&#945; first binds CLC:CLF-1 to form a membrane-associated trimeric complex, but it also connects to sorLA via the free sorLA-binding site in CLF-1. As a result, CNTFR&#945;, which has no capacity for endocytosis on its own, is tugged along and internalized by the sorLA-mediated endocytosis of CLC:CLF-1.
The present protocol describes the experimental procedures used to demonstrate i) the sorLA-mediated and CLC:CLF-1-dependent downregulation of surface-membrane CNTFR&#945; expression; ii) sorLA-mediated endocytosis and lysosomal targeting of CNTFR&#945;; and iii) the lowered cellular response to CLC:CLF-1-stimulation upon sorLA-mediated downregulation of CNTFR&#945;.

The present protocol describes how Western blotting and immunocytochemistry combined with inhibition of lysosomal enzymes can be used to demonstrate the downregulation of Ciliary Neurotrophic Factor Receptor-&#945; (CNTFR&#945;), which is conveyed by the interaction between Cytokine-like Factor-1 (CLF-1) and the endocytic receptor sorLA.

The heterodimeric cytokine Cardiotrophin-like Cytokine:Cytokine-like Factor-1 (CLC:CLF-1) targets the glycosylphosphatidylinositol (GPI)-anchored ...

A Protein Preparation Method for the High-throughput Identification of Proteins Interacting with a Nuclear Cofactor Using LC-MS/MS Analysis

Transcriptional coregulators are vital to the efficient transcriptional regulation of nuclear chromatin structure. Coregulators play a variety of roles in regulating transcription. These include the direct interaction with transcription factors, the covalent modification of histones and other proteins, and the occasional chromatin conformation alteration. Accordingly, establishing relatively quick methods for identifying proteins that interact within this network is crucial to enhancing our understanding of the underlying regulatory mechanisms. LC-MS/MS-mediated protein binding partner identification is a validated technique used to analyze protein-protein interactions. By immunoprecipitating a previously-identified member of a protein complex with an antibody (occasionally with an antibody for a tagged protein), it is possible to identify its unknown protein interactions via mass spectrometry analysis. Here, we present a method of protein preparation for the LC-MS/MS-mediated high-throughput identification of protein interactions involving nuclear cofactors and their binding partners. This method allows for a better understanding of the transcriptional regulatory mechanisms of the targeted nuclear factors.

We have established a method for the purification of coregulatory interaction proteins using the LC-MS/MS system.

Transcriptional coregulators are vital to the efficient transcriptional regulation of nuclear chromatin structure. Coregulators play a variety of roles in ...

A Tailored HPLC Purification Protocol That Yields High-purity Amyloid Beta 42 and Amyloid Beta 40 Peptides, Capable of Oligomer Formation

Amyloidogenic peptides such as the Alzheimer's disease-implicated Amyloid beta (A&#946;), can present a significant challenge when trying to obtain high purity material. Here we present a tailored HPLC purification protocol to produce high-purity amyloid beta 42 (A&#946;42) and amyloid beta 40 (A&#946;40) peptides. We have found that the combination of commercially available hydrophobic poly(styrene/divinylbenzene) stationary phase, polymer laboratory reverse phase - styrenedivinylbenzene (PLRP-S) under high pH conditions, enables the attainment of high purity (&gt;95%) A&#946;42 in a single chromatographic run. The purification is highly reproducible and can be amended to both semi-preparative and analytical conditions depending upon the amount of material wished to be purified. The protocol can also be applied to the A&#946;40 peptide with identical success and without the need to alter the method.

Herein we report a tailored HPLC purification protocol that yields high-purity amyloid beta 42 (A&#946;42) and amyloid beta 40 (A&#946;40) peptides, capable of oligomer formation. Amyloid beta is a highly aggregation prone, hydrophobic peptide implicated in Alzheimer&#39;s disease. The amyloidogenic nature of the peptide makes its purification a challenge.

Amyloidogenic peptides such as the Alzheimer's disease-implicated Amyloid beta (A&#946;), can present a significant challenge when trying to obtain high ...

A Western Blotting Protocol for Small Numbers of Hematopoietic Stem Cells

Hematopoietic stem cells (HSCs) are rare cells, with the mouse bone marrow containing only ~25,000 phenotypic long term repopulating HSCs. A Western blotting protocol was optimized and suitable for the analysis of small numbers of HSCs (500 - 15,000 cells). Phenotypic HSCs were purified, accurately counted, and directly lysed in Laemmli sample buffer. Lysates containing equal numbers of cells were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the blot was prepared and processed following standard Western blotting protocols. Using this protocol, 2,000 - 5,000 HSCs can be routinely analyzed, and in some cases data can be obtained from as few as 500 cells, compared to the 20,000 to 40,000 cells reported in most publications. This protocol should be generally applicable to other hematopoietic cells, and enables the routine analysis of small numbers of cells using standard laboratory procedures.

A standard Western blotting protocol was optimized for analyzing as few as 500 hematopoietic stem or progenitor cells. Optimization involves careful handling of the cell sample, limiting transfers between tubes, and directly lysing the cells in Laemmli sample buffer.

Hematopoietic stem cells (HSCs) are rare cells, with the mouse bone marrow containing only ~25,000 phenotypic long term repopulating HSCs. A Western ...

High Throughput, Absolute Determination of the Content of a Selected Protein at Tissue Levels Using Quantitative Dot Blot Analysis (QDB)

Lacking a convenient, quantitative, high throughput immunoblot method for absolute determination of the content of a specific protein at cellular and tissue level significantly hampers the progress in proteomic research. Results derived from currently available immunoblot techniques are also relative, preventing any efforts to combine independent studies with a large-scale analysis of protein samples. In this study, we demonstrate the process of quantitative dot blot analysis (QDB) to achieve absolute quantification in a high throughput format. Using a commercially available protein standard, we are able to determine the absolute content of capping actin protein, gelsolin-like (CAPG) in protein samples prepared from three different mouse tissues (kidney, spleen, and prostate) together with a detailed explanation of the experimental details. We propose the QDB analysis as a convenient, quantitative, high throughput immunoblot method of absolute quantification of individual proteins at the cellular and tissue level. This method will substantially aid biomarker validation and pathway verification in various areas of biological and biomedical research.

High Throughput, Absolute Determination of the Content of a Selected Protein at Tissue Levels Using Quantitative Dot Blot Analysis QDB

Here we demonstrate a detailed process of quantitative dot blot analysis (QDB) by determining the absolute content of a targeted protein, capping actin protein, gelsolin-like (CAPG), in three different mouse tissues. We demonstrate a high throughput, convenient, quantitative immunoblot technique for biomarker validation at the cellular and tissue level.

Lacking a convenient, quantitative, high throughput immunoblot method for absolute determination of the content of a specific protein at cellular and ...

Robust Comparison of Protein Levels Across Tissues and Throughout Development Using Standardized Quantitative Western Blotting

Western blotting is a technique that is commonly used to detect and quantify protein expression. Over the years, this technique has led to many advances in both basic and clinical research. However, as with many similar experimental techniques, the outcome of Western blot analyses is easily influenced by choices made in the design and execution of the experiment. Specific housekeeping proteins have traditionally been used to normalize protein levels for quantification, however, these have a number of limitations and have therefore been increasingly criticized over the past few years. Here, we describe a detailed protocol that we have developed to allow us to undertake complex comparisons of protein expression variation across different tissues, mouse models (including disease models), and developmental timepoints. By using a fluorescent total protein stain and introducing the use of an internal loading standard, it is possible to overcome existing limitations in the number of samples that can be compared within experiments and systematically compare protein levels across a range of experimental conditions. This approach expands the use of traditional western blot techniques, thereby allowing researchers to better explore protein expression across different tissues and samples.

This method describes a robust and reproducible approach for the comparison of protein levels in different tissues and at different developmental timepoints using a standardized quantitative western blotting approach.

Western blotting is a technique that is commonly used to detect and quantify protein expression. Over the years, this technique has led to many advances ...

TMT Sample Preparation for Proteomics Facility Submission and Subsequent Data Analysis

Proteomic technologies are powerful methodologies that can aid our understanding of mechanisms of action in biological systems by providing a global view of the impact of a disease, treatment, or other condition on the proteome as a whole. This report provides a detailed protocol for the extraction, quantification, precipitation, digestion, labeling, and subsequent data analysis of protein samples. Our optimized TMT labeling protocol requires a lower tag-label concentration and achieves consistently reliable data. We have used this protocol to evaluate protein expression profiles in a variety of mouse tissues (i.e., heart, skeletal muscle, and brain) as well as cells cultured in vitro. In addition, we demonstrate how to evaluate thousands of proteins from the resulting dataset.

We present an optimized tandem mass tag (TMT) labeling protocol that includes detailed information for each of the following steps: protein extraction, quantification, precipitation, digestion, labeling, submission to a proteomics facility, and data analyses.

Proteomic technologies are powerful methodologies that can aid our understanding of mechanisms of action in biological systems by providing a global view ...

Routine Collection of High-Resolution cryo-EM Datasets Using 200 KV Transmission Electron Microscope

Cryo-electron microscopy (cryo-EM) has been established as a routine method for protein structure determination during the past decade, taking an ever-increasing share of published structural data. Recent advances in TEM technology and automation have boosted both the speed of data collection and quality of acquired images while simultaneously decreasing the required level of expertise for obtaining cryo-EM maps at sub-3 &#197; resolutions. While most of such high-resolution structures have been obtained using state-of-the-art 300 kV cryo-TEM systems, high-resolution structures can be also obtained with 200 kV cryo-TEM systems, especially when equipped with an energy filter. Additionally, automation of microscope alignments and data collection with real-time image quality assessment reduces system complexity and assures optimal microscope settings, resulting in increased yield of high-quality images and overall throughput of data collection. This protocol demonstrates the implementation of recent technological advances and automation features on a 200 kV cryo-transmission electron microscope and shows how to collect data for the reconstruction of 3D maps that are sufficient for de novo atomic model building. We focus on best practices, critical variables, and common issues that must be considered to enable the routine collection of such high-resolution cryo-EM datasets. Particularly the following essential topics are reviewed in detail: i) automation of microscope alignments, ii) selection of suitable areas for data acquisition, iii) optimal optical parameters for high-quality, high-throughput data collection, iv) energy filter tuning for zero-loss imaging, and v) data management and quality assessment. Application of the best practices and improvement of achievable resolution using an energy filter will be demonstrated on the example of apo-ferritin that was reconstructed to 1.6 &#197;, and Thermoplasma acidophilum 20S proteasome reconstructed to 2.1-&#197; resolution using a 200 kV TEM equipped with an energy filter and a direct electron detector.

High-resolution cryo-EM maps of macromolecules can be also achieved by using 200 kV TEM microscopes. This protocol shows the best practices for setting accurate optics alignments, data acquisition schemes, and selection of imaging areas that are all essential for the successful collection of high-resolution datasets using a 200 kV TEM.

Cryo-electron microscopy (cryo-EM) has been established as a routine method for protein structure determination during the past decade, taking an ...

Study of the Functions and Activities of Neuronal K-Cl Co-Transporter KCC2 Using Western Blotting

Potassium chloride cotransporters 2 (KCC2) is a member of the solute carrier family 12 (SLC12) of cation-chloride-cotransporters (CCCs), found exclusively in the neuron and is essential for the proper functioning of Cl- homeostasis and consequently functional GABAergic inhibition. Failure in proper regulation of KCC2 is deleterious and has been associated with the prevalence of several neurological diseases, including epilepsy. There has been considerable progress with regard to understanding the mechanisms involved in the regulation of KCC2, accredited to the development of techniques that enable researchers to study its functions and activities; either via direct (assessing kinase regulatory sites phosphorylation) or indirect (observing and monitoring GABA activity) investigations. Here, the protocol highlights how to investigate KCC2 phosphorylation at kinase regulatory sites - Thr906 and Thr1007- using western blotting technique. There are other classic methods used to directly measure KCC2 activity, such as rubidium ion and thallium ion uptake assay. Further techniques such as patch-clamp-electrophysiology are used to measure GABA activity; hence, indirectly reflecting activated and/or inactivated KCC2 as informed by the assessment of intracellular chloride ion homeostasis. A few of these additional techniques will be briefly discussed in this manuscript.

The present protocol highlights the application of western blotting technique to study the functions and activities of neuronal K-Cl co-transporter KCC2. The protocol describes the investigation of KCC2 phosphorylation at kinase regulatory sites Thr906/1007 via western blotting. Also, additional methods to confirm KCC2 activity are briefly highlighted in this text.

Potassium chloride cotransporters 2 (KCC2) is a member of the solute carrier family 12 (SLC12) of cation-chloride-cotransporters (CCCs), found exclusively ...

Assessing Hepatic Steatosis with 3D Fluorescence Lipid Droplet Reconstruction

Analysis of Fluorescent-Stained Lipid Droplets with 3D Reconstruction for Hepatic Steatosis Assessment

Lipid droplets (LDs) are specialized organelles that mediate lipid storage and play a very important role in suppressing lipotoxicity and preventing dysfunction caused by free fatty acids (FAs). The liver, given its critical role in the body's fat metabolism, is persistently threatened by the intracellular accumulation of LDs in the form of both microvesicular and macrovesicular hepatic steatosis. The histologic characterization of LDs is typically based on lipid-soluble diazo dyes, such as Oil Red O (ORO) staining, but a number of disadvantages consistently hamper the use of this analysis with liver specimens. More recently, lipophilic fluorophores 493/503 have become popular for visualizing and locating LDs due to their rapid uptake and accumulation into the neutral lipid droplet core. Even though most applications are well-described in cell cultures, there is less evidence demonstrating the reliable use of lipophilic fluorophore probes as an LD imaging tool in tissue samples. Herein, we propose an optimized boron dipyrromethene (BODIPY) 493/503-based protocol for the evaluation of LDs in liver specimens from an animal model of high-fat diet (HFD)-induced hepatic steatosis. This protocol covers liver sample preparation, tissue sectioning, BODIPY 493/503 staining, image acquisition, and data analysis. We demonstrate an increased number, intensity, area ratio, and diameter of hepatic LDs upon HFD feeding. Using orthogonal projections and 3D reconstructions, it was possible to observe the full content of neutral lipids in the LD core, which appeared as nearly spherical droplets. Moreover, with the fluorophore BODIPY 493/503, we were able to distinguish microvesicles (1 &#181;m &lt; d &#8804; 3 &#181;m), intermediate vesicles (3 &#181;m &lt; d &#8804; 9 &#181;m), and macrovesicles (d &gt; 9 &#181;m), allowing the successful discrimination of microvesicular and macrovesicular steatosis. Overall, this BODIPY 493/503 fluorescence-based protocol is a reliable and simple tool for hepatic LD characterization and may represent a complementary approach to the classical histological protocols.

Author Spotlight: Analysis of Fluorescent-Stained Lipid Droplets with 3D Reconstruction for Hepatic Steatosis Assessment  

Herein, we demonstrate an optimized BODIPY 493/503 fluorescence-based protocol for lipid droplet characterization in liver tissue. Through the use of orthogonal projections and 3D reconstructions, the fluorophore allows for successful discrimination between microvesicular and macrovesicular steatosis and may represent a complementary approach to the classical histological protocols for hepatic steatosis assessment.

Lipid droplets (LDs) are specialized organelles that mediate lipid storage and play a very important role in suppressing lipotoxicity and preventing ...