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 solution at 4 &#176;C for up to 1 month.</li>
	<li>Prepare an anti-A&#946; antibody 6E10 solution (1:1,000) by adding 10 &#181;L of antibody stock solution to 10 mL of 5% BSA solution. Mix them completely by vortexing. Store the solution at 4 &#176;C for up to 1 month.</li>
	<li>Prepare an anti-fibrillar oligomer antibody OC solution (1:1,000) by adding 10 &#181;L of antibody stock solution to 10 mL of 5% BSA solution. Mix them completely by vortexing. Store the solution at 4 &#176;C for up to 1 month.</li>
	<li>Prepare a Tris-buffered saline (TBS) stock solution by adding 24 g of Tris base and 88 g of NaCl to 1,000 mL of double-distilled water. Adjust the pH to 7.4. Store the solution at 4 &#176;C for up to 3 months.</li>
	<li>Prepare a Tris-buffered saline and Tween-20 (TBST) solution by adding 1 mL of Tween-20 to 100 mL of TBS stock solution and 900 mL double-distilled water.</li>
	<li>Prepare a secondary antibody solution by adding 10 &#181;L of horseradish peroxidase (HRP) Goat anti-Rabbit IgG (H + L) to 10 mL of TBST solution. Mix them completely by vortexing them. Store the solution at 4 &#176;C for up to 1 month.</li>
	<li>Dissolve 3.68 g of curcumin in 1 mL of dimethyl sulfoxide (DMSO) to form a 10-mM curcumin stock solution.</li>
	<li>Dissolve 5 mg of synthetic A&#946;1-42 in 2 mL of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) to form a 2.5-mg/mL A&#946; monomer solution. Place it at room temperature (25 &#176;C) for 20 min. Make 100 &#181;L aliquots and store at -20 &#176;C for up to 6 months. 
	NOTE: This procedure should be run as fast as possible. The pipette tips should be cut off to ensure accurate pipetting.</li>
	<li>Prepare electrochemiluminescence (ECL) fluid by mixing ECL fluid A and B with a volume ratio of 1:1. This solution should be prepared just before use.</li>
</ol>
2. Sample Preparation
NOTE: Perform the sample preparation 2 days before the dot blotting analysis.
<ol>
	<li>Add 900 &#181;L of double-distilled water to a tube of A&#946;1-42 monomer solution; the concentration of A&#946;1-42 will be 0.25 mg/mL. Place the mixture at room temperature for 20 min.</li>
	<li>Evaporate the solution with high-purity nitrogen gas until its volume is about 850 &#181;L. The concentration of the A&#946;1-42 solution will be about 0.29 mg/mL. 
	NOTE: The solution should be shaken from time to time to ensure the HFIP is fully evaporated. Normally, after 30 min of evaporation, the volume of the residual solution is about 850 &#181;L.</li>
	<li>Dilute the curcumin stock solution to a curcumin working solution (0.2 and 2 &#181;M) with double-distilled water. Mix the A&#946;1-42solution and curcumin working solution with a volume ratio of 1:1. The final concentrations of curcumin will be 0.1 and 1 &#181;M. 
	NOTE: Potential oligomer inhibitors can be mixed with the A&#946;1-42 solution in any ratio if needed.</li>
	<li>Shake the solution continuously in a magnetic agitator (see Table of Materials).
	<ol>
		<li>Fix a plastic divider box to the magnetic agitator. Place 2 magnetic stir bars at 2 corners of the box and place the sample tubes in the center of the box.</li>
		<li>Shake the box at room temperature (25 &#176;C) for 48 h. 
		NOTE: The speed of the magnetic agitator is around 60 rpm.</li>
	</ol>
	</li>
	<li>Centrifuge the tubes for 15 min at 4 &#176;C and 18,000 x g. Collect the supernatant.</li>
</ol>
3. Dot Blotting Analysis
NOTE: All incubations are performed on a horizontal shaker.
<ol>
	<li>Cut nitrocellulose membrane into 1-cm wide strips. 
	NOTE: The width of the nitrocellulose membrane can be adjusted according to experimental needs.</li>
	<li>Place 2-&#181;L samples evenly on 2 strips (strip 1 and 2) with each point interval at 0.5 cm.</li>
	<li>Place the strips at room temperature for 5 min until the droplet on the band is dry.</li>
	<li>Incubate the strips with a 5% BSA solution for 30 min at room temperature.</li>
	<li>Rinse the strips with a TBST solution for 5 min at room temperature.</li>
	<li>Aspirate the TBST solution. For 1 h at room temperature, incubate strip 1 with an anti-oligomer antibody A11 solution and strip 2 with an anti-A&#946; antibody 6E10 solution.</li>
	<li>Rinse the strips with a TBST solution three times, each time for 5 min at room temperature.</li>
	<li>Aspirate the TBST solution. Incubate the strips with a secondary antibody solution for 40 min at room temperature.</li>
	<li>Rinse the strips with a TBST solution three times, each time for 5 min at room temperature.</li>
	<li>Evenly apply the mixed ECL fluid to the surface of the strips. Expose the strips in an automatic chemiluminescence imaging system (see Table of Materials). 
	NOTE: Normally, 300 &#181;L of ECL fluid is enough for one membrane. The membrane must be kept moist during the exposure. The exposure time is automatically calculated by the imaging system.</li>
	<li>Do a grayscale analysis using ImageJ (National Institutes of Health) or another image-processing software to obtain semi-quantitative results.</li>
</ol>

<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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The authors have nothing to disclose.

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 ÃŽÂ²-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 ...

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

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Biochemistry

11.7K Views.  Ningbo University. This protocol describes how to prepare Aβ oligomers from a synthetic peptide in vitro and to evaluate relative amounts of Aβ oligomer by a dot blotting analysis.

Video: A11-positive β-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis

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 ...

Preparation of Fungal and Plant Materials for Structural Elucidation Using Dynamic Nuclear Polarization Solid-State NMR

This protocol shows how uniformly 13C, 15N-labeled fungal materials can be produced and how these soft materials should be proceeded for solid-state NMR and sensitivity-enhanced DNP experiments. The sample processing procedure of plant biomass is also detailed. This method allows the measurement of a series of 1D and 2D 13C-13C/15N correlations spectra, which enables high-resolution structural elucidation of complex biomaterials in their native state, with minimal perturbation. The isotope-labeling can be examined by quantifying the intensity in 1D spectra and the polarization transfer efficiency in 2D correlation spectra. The success of dynamic nuclear polarization (DNP) sample preparation can be evaluated by the sensitivity enhancement factor. Further experiments examining the structural aspects of the polysaccharides and proteins will lead to a model of the three-dimensional architecture. These methods can be modified and adapted to investigate a wide range of carbohydrate-rich materials, including the natural cell walls of plants, fungi, algae and bacteria, as well as synthesized or designed carbohydrate polymers and their complex with other molecules.

A protocol for preparing 13C,15N-labeled fungal and plant samples for multidimensional solid-state NMR spectroscopy and dynamic nuclear polarization (DNP) investigations is presented.

This protocol shows how uniformly 13C, 15N-labeled fungal materials can be produced and how these soft materials should be proceeded for solid-state NMR ...

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 ...

A Plasma Sample Preparation for Mass Spectrometry using an Automated Workstation

Sample preparation for mass spectrometry analysis in proteomics requires enzymatic cleavage of proteins into a peptide mixture. This process involves numerous incubation and liquid transfer steps in order to achieve denaturation, reduction, alkylation, and cleavage. Adapting this workflow onto an automated workstation can increase efficiency and reduce coefficients of variance, thereby providing more reliable data for statistical comparisons between sample types. We previously described an automated proteomic sample preparation workflow1. Here, we report the development of a more efficient and better controlled workflow with the following advantages: 1) The number of liquid transfer steps is reduced from nine to six by combining reagents; 2) Pipetting time is reduced by selective tip pipetting using a 96-position pipetting head with multiple channels; 3) Potential throughput is increased by the availability of up to 45 deck positions; 4) Complete enclosure of the system provides improved temperature and environmental control and reduces the potential for contamination of samples or reagents; and 5) The addition of stable isotope labeled peptides, as well as &#946;-galactosidase protein, to each sample makes monitoring and quality control possible throughout the entire process. These hardware and process improvements provide good reproducibility and improve intra-assay and inter-assay precision (CV of less than 20%) for LC-MS based protein and peptide quantification. The entire workflow for digesting 96 samples in a 96-well plate can be completed in approximately 5 hours.

Here, we present an automated plasma protein digestion method for mass spectrometry-based quantitative proteomic analysis. In this protocol, the liquid transferring and incubation steps for protein denaturation, reduction, alkylation, and trypsin digestion reactions are streamlined and automated. It takes approximately five hours to prepare a 96-well plate with desired precision.

Sample preparation for mass spectrometry analysis in proteomics requires enzymatic cleavage of proteins into a peptide mixture. This process involves ...

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 ...

Sample Preparation and Relative Quantitation using Reductive Methylation of Amines for Peptidomics Studies

Peptidomics can be defined as the qualitative and quantitative analysis of peptides in a biological sample. Its main applications include identifying the peptide biomarkers of disease or environmental stress, identifying neuropeptides, hormones, and bioactive intracellular peptides, discovering antimicrobial and nutraceutical peptides from protein hydrolysates, and can be used in studies to understand the proteolytic processes. The recent advance in sample preparation, separation methods, mass spectrometry techniques, and computational tools related to protein sequencing has contributed to the increase of the identified peptides number and peptidomes characterized. Peptidomic studies frequently analyze peptides that are naturally generated in cells. Here, a sample preparation protocol based on heat-inactivation is described, which eliminates protease activity, and extraction with mild conditions, so there is no peptide bonds cleavage. In addition, the relative quantitation of peptides using stable isotope labeling by reductive methylation of amines is also shown. This labeling method has some advantages as the reagents are commercially available, inexpensive compared to others, chemically stable, and allows the analysis of up to five samples in a single LC-MS run.

This article describes a sample preparation method based on heat-inactivation to preserve endogenous peptides avoiding degradation post-mortem, followed by relative quantitation using isotopic labeling plus LC-MS.

Peptidomics can be defined as the qualitative and quantitative analysis of peptides in a biological sample. Its main applications include identifying the ...