The authors acknowledge COST Action CM1406 (Epigenetic Chemical Biology). Research reported in this publication was supported by the Pierre Mercier foundation.

1. Cell Culture
NOTE: The following steps are performed in a standard tissue culture hood. Familiarity with sterile technique is expected.
<ol>
	<li>Culture HeLa cells to 80% confluency in a T75 cell culture flask in MEM supplemented with 10% fetal bovine serum, penicillin G (100 U/mL), and streptomycin (100 mg/mL). 
	NOTE: Cell culture, treatment, and lysis steps are conducted under laminar flow, with cell incubation steps at 37 &#176;C performed in a humidified atmosphere of 5% CO<sub...

<ol>
	<li>Arrowsmith, C. H., Bountra, C., Fish, P. V., Lee, K., Schapira, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetic+protein+families:+a+new+frontier+for+drug+discovery.">Epigenetic protein families: a new frontier for drug discovery.</a> Nat Rev Drug Discov. 11 (5), 384-400 (2012).</li><li>Henikoff, S., Greally, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epigenetics,+cellular+memory+and+gene+regulation.">Epigenetics, cellular memory and gene regulation.</a> Curr Biol. 26 (14), R644-R648 (2016).</li><li>Kim, C., 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=HDAC6+inhibitor+blocks+amyloid+beta-induced+impairment+of+mitochondrial+transport+in+hippocampal+neurons.">HDAC6 inhibitor blocks amyloid beta-induced impairment of mitochondrial transport in hippocampal neurons.</a> PLoS One. 7 (8), (2012).</li><li>Kawaguchi, 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=The+deacetylase+HDAC6+regulates+aggresome+formation+and+cell+viability+in+response+to+misfolded+protein+stress.">The deacetylase HDAC6 regulates aggresome formation and cell viability in response to misfolded protein stress.</a> Cell. 115 (6), 727-738 (2003).</li><li>Zhao, 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=Acetylation+of+p53+at+lysine+373/382+by+the+histone+deacetylase+inhibitor+depsipeptide+induces+expression+of+p21(Waf1/Cip1).">Acetylation of p53 at lysine 373/382 by the histone deacetylase inhibitor depsipeptide induces expression of p21(Waf1/Cip1).</a> Mol Cell Biol. 26 (7), 2782-2790 (2006).</li><li>Berger, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histone+modifications+in+transcriptional+regulation.">Histone modifications in transcriptional regulation.</a> Curr Opin Genet Dev. 12 (2), 142-148 (2002).</li><li>Sim&#245;es-Pires, C., 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=HDAC6+as+a+target+for+neurodegenerative+diseases:+what+makes+it+different+from+the+other+HDACs?.">HDAC6 as a target for neurodegenerative diseases: what makes it different from the other HDACs?.</a> Mol Neurodegener. 8 (7), 1-16 (2013).</li><li>Mottamal, M., Zheng, S., Huang, T. L., Wang, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histone+deacetylase+inhibitors+in+clinical+studies+as+templates+for+new+anticancer+agents.">Histone deacetylase inhibitors in clinical studies as templates for new anticancer agents.</a> Molecules. 20 (3), 3898-3941 (2015).</li><li>Manal, M., Chandrasekar, M. J., Gomathi Priya, J., Nanjan, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibitors+of+histone+deacetylase+as+antitumor+agents:+A+critical+review.">Inhibitors of histone deacetylase as antitumor agents: A critical review.</a> Bioorg Chem. 67, 18-42 (2016).</li><li>Mack, G. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=To+selectivity+and+beyond.">To selectivity and beyond.</a> Nat Biotech. 28 (12), 1259-1266 (2010).</li><li>. Study of ACY-1215 alone and in combination with bortezomib and dexamethasone in multiple myeloma (ACY-1215) Available from: <a target="_blank" href="https://clinicaltrials.gov/ct2/show/NCT01323751">https://clinicaltrials.gov/ct2/show/NCT01323751</a> (1211)</li><li>. Study of ACY-1215 in combination with lenalidomide, and dexamethasone in multiple myeloma Available from: <a target="_blank" href="https://clinicaltrials.gov/ct2/show/NCT01583283">https://clinicaltrials.gov/ct2/show/NCT01583283</a> (2012)</li><li>. 13ACY-1215 (ricolinostat) in combination with pomalidomide and low-dose dex in relapsed-and-refractory multiple myeloma Available from: <a target="_blank" href="https://clinicaltrials.gov/ct2/show/NCT01997840">https://clinicaltrials.gov/ct2/show/NCT01997840</a> (2013)</li><li>. Study of ACY-241 alone and in combination with pomalidomide and dexamethasone in multiple myeloma Available from: <a target="_blank" href="https://clinicaltrials.gov/ct2/show/NCT02400242">https://clinicaltrials.gov/ct2/show/NCT02400242</a> (2015)</li><li>Yee, A. J., 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=Ricolinostat+plus+lenalidomide,+and+dexamethasone+in+relapsed+or+refractory+multiple+myeloma:+a+multicentre+phase+1b+trial.">Ricolinostat plus lenalidomide, and dexamethasone in relapsed or refractory multiple myeloma: a multicentre phase 1b trial.</a> Lancet Oncol. 17 (11), 1569-1578 (2016).</li><li>Jung, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homogenous+non-isotopic+assays+for+histone+deacetylase+activity.">Homogenous non-isotopic assays for histone deacetylase activity.</a> Expert Opin Ther Pat. 13 (6), 935 (2003).</li><li>Zwick, V., Sim&#245;es-Pires, C., Cuendet, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-based+multi-substrate+assay+coupled+to+UHPLC-ESI-MS/MS+for+a+quick+identification+of+class-specific+HDAC+inhibitors.">Cell-based multi-substrate assay coupled to UHPLC-ESI-MS/MS for a quick identification of class-specific HDAC inhibitors.</a> J Enzyme Inhibi Med Chem. 31 (1), 209-214 (2016).</li><li>Khan, N., 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=Determination+of+the+class+and+isoform+selectivity+of+small-molecule+histone+deacetylase+inhibitors.">Determination of the class and isoform selectivity of small-molecule histone deacetylase inhibitors.</a> Biochem J. 409 (2), 581-589 (2008).</li><li>Glaser, K. B., 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=Differential+protein+acetylation+induced+by+novel+histone+deacetylase+inhibitors.">Differential protein acetylation induced by novel histone deacetylase inhibitors.</a> Biochem Biophys Res Commun. 325 (3), 683-690 (2004).</li><li>Butler, K. V., 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=Rational+design+and+simple+chemistry+yield+a+superior,+neuroprotective+HDAC6+inhibitor,+tubastatin+A.">Rational design and simple chemistry yield a superior, neuroprotective HDAC6 inhibitor, tubastatin A.</a> J Am Chem Soc. 132 (31), 10842-10846 (2010).</li><li>Jung, M., Yong, K. -. J., Velena, A., Lee, S., Sippl, W., Jung, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-Based+Assays+for+HDAC+Inhibitor+Hit+Validation.">Cell-Based Assays for HDAC Inhibitor Hit Validation.</a> Epigenetic Targets in Drug Discovery. , (2010).</li><li>Milli, A., 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=Proteomic+analysis+of+cellular+response+to+novel+proapoptotic+agents+related+to+atypical+retinoids+in+human+IGROV-1+ovarian+carcinoma+cells.">Proteomic analysis of cellular response to novel proapoptotic agents related to atypical retinoids in human IGROV-1 ovarian carcinoma cells.</a> J Proteome Res. 10 (3), 1191-1207 (2011).</li><li>Zwick, V., 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=Synthesis+of+a+selective+HDAC6+inhibitor+active+in+neuroblasts.">Synthesis of a selective HDAC6 inhibitor active in neuroblasts.</a> Bioorg Med Chem Lett. 26 (20), 4955-4959 (2016).</li><li>Ciossek, T., Julius, H., Wieland, H., Maier, T., Beckers, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+homogeneous+cellular+histone+deacetylase+assay+suitable+for+compound+profiling+and+robotic+screening.">A homogeneous cellular histone deacetylase assay suitable for compound profiling and robotic screening.</a> Anal Biochem. 372 (1), 72-81 (2008).</li><li>Heltweg, B., Dequiedt, F., Marshall, B. 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HDAC inhibition is a hot topic in drug discovery, with a current focus on HDAC6-selective inhibitors for cancer therapy21. HDAC selectivity is usually assessed by a series of high-throughput, cell-free assays, which intend to determine the inhibitory potency towards individual HDAC isoforms21. However, the selectivity of an inhibitor must be additionally confirmed in living cells by evaluating the acetylation status of endogenous protein substrates, such as histones (for cl...

HDACs belong to a family of enzymes able to deacetylate histones within the chromatin structure. They also have other protein substrates in the cytosol and are located in various cell compartments. A total of 18 HDAC isoforms have been identified so far and have been related to several cell mechanisms, including the regulation of transcription factors and gene expression, as well as cell signaling and transport1,2,3,4,5,6,7. HDAC catalytic inhibitors have emerged as potential therapeutic drugs for cancer therapy. Most HDAC inhibitors currently approved by the FDA are for the treatment of T-cell lymphoma and multiple myeloma, and are non-specific HDAC inhibitors, such as vorinostat (SAHA), belinostat, and panobinostat8,9. However, a series of side effects have been associated with pan-inhibitors, and the search for isoform-specific small molecules is a hot topic in medicinal chemistry and drug discovery. Accordingly, the class I (HDAC1-3 and HDAC8) selective inhibitor romidepsin is an already approved drug10, while HDAC6-specific inhibitors are currently under clinical trials, with increased therapeutic potential in multiple myeloma11,12,13,14,15.
Screening assays to characterize HDAC inhibitors are based on the incubation of an HDAC substrate with an enzymatic source (single isoform, nuclear extract, or cell lysate). The substrate is usually a small peptide sequence containing an acetyl lysine residue coupled to a cleavable fluorophore (e.g., coumarin), such as N-(4-methyl-7-aminocoumarinyl)-N&#945;-(t-butoxycarbonyl)-N&#969;-acetyllysineamide (MAL)16. To distinguish between isoform-specific activities, separate cell-free assays involving each isoform are necessary and might not reflect the real isoform activity in living cells. Isoform-specific substrates are commercially available, such as benzyl (S)-[1-(4-methyl-2-oxo-2H-chromen-7-ylcarbamoyl)-5-propionylaminopentyl]carbamate (MOCPAC, HDAC1 specific substrate) and (S)-[5-acetylamino-1-(2-oxo-4-trifluoromethyl-2H-chromen-7-ylcarbamoyl)pentyl]carbamic acid tert-butyl ester (BATCP, HDAC6 specific substrate) (Figure 1B). However, a multi-substrate mixture containing MAL, MOCPAC, and BATCP given to living cells will not permit the detection of the individual deacetylated products by fluorometric measurement, given that they bear the same cleavable fluorophore.
The method described here allows for the detection and relative quantification of each substrate and its deacetylated product in HeLa cells using a multi-substrate assay followed by UHPLC-ESI-MS/MS analysis17. An HDAC assay is conducted on HeLa cells to enable the direct identification of HDAC inhibitory activity and of the specificity of test compounds on endogenous HDACs. There is a focus on HDAC1 and HDAC6, which are simultaneously evaluated. To achieve these enzymatic measurements in a single incubation assay, a mixture of non-specific and specific HDAC substrates is added to treated and untreated HeLa cells plated on a 96-well plate. Following an incubation step, cells are lysed to release the substrates and their respective reaction products, which are separated and detected using a UHPLC-MS method (Figure 1C). The deacetylated products of the MAL, MOCPAC, and BATCP substrates are the deacetylated MAL (dMAL), deacetylated MOCPAC (dMOCPAC), and deacetylated BATCP (dBATCP), respectively. Dose-response curves can be built with active compounds.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55878/55878fig1.jpg" /> 
Figure 1: General scheme for the cell-based HDAC assay to identify HDAC1- and HDAC6-specific inhibitors by the UHPLC-MS analysis of multiple substrates. (A) Scheme of a typical 96-well plate containing treated (test compounds) and untreated (control) HeLa cells, as well as cell-free blanks. (B) Chemical structure of substrates added as a mixture (21 &#181;M each) to be deacetylated by endogenous HDACs. (C) Typical UHPLC-MS chromatogram showing the peaks of the added substrates (MAL, MOCPAC, and BATCP) and their deacetylated products (dMAL, dMOCPAC, and dBACTP, respectively). <a href="http://cloudflare.jove.com/files/ftp_upload/55878/55878fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="0" cellpadding="0" cellspacing="0" width="887">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">BATCP</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td style="width:152px;">B4061</td>
			<td style="width:273px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MAL</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td>SCP0168</td>
			<td>Synonym: BOC-Ac-Lys-AMC&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">MOCPAC</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td>M2195</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">MS275</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td style="width:152px;">EPS002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Trichostatin A</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td style="width:152px;">T8552</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Tubastatin A</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td style="width:152px;">SML0044</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Acetonitrile, HPLC grade</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:152px;">10660131</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Formic acid, LC/MS grade</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:152px;">10596814</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:271px;">H2O, HPLC grade</td>
			<td style="width:191px;"></td>
			<td style="width:152px;"></td>
			<td>distilled H2O filtered through a Milli-Q purification system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">HeLa cells</td>
			<td style="width:191px;">ATCC</td>
			<td style="width:152px;">ATCC CRM-CCL-2</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cell dissociation reagent TrypLE Express</td>
			<td style="width:191px;">ThermoFisher Scientific</td>
			<td style="width:152px;">12604013</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">DMSO, cell culture grade</td>
			<td style="width:191px;">Applichem</td>
			<td style="width:152px;">146463</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">DPBS</td>
			<td style="width:191px;">ThermoFisher Scientific</td>
			<td>14190144</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Fetal bovine serum&#160;</td>
			<td style="width:191px;">Biowest</td>
			<td>S1810</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">MEM</td>
			<td style="width:191px;">ThermoFisher Scientific</td>
			<td>22561021</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin-Streptomycin</td>
			<td style="width:191px;">Bioconcept</td>
			<td>4-01F00-H&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10X RIPA buffer</td>
			<td style="width:191px;">Abcam</td>
			<td style="width:152px;">ab156034</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">SigmaFast protease inhibitor tablets</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td style="width:152px;">S8820</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">96-well plates, sterile, flat-bottom, tissue culture treated Corning</td>
			<td style="width:191px;">VWR</td>
			<td style="width:152px;">29442-058</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">96-well plates, non-sterile, V-bottom Corning</td>
			<td style="width:191px;">VWR</td>
			<td style="width:152px;">29442-404</td>
			<td>used in the centrifugation step</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">96-well plate, conical bottom, Nunc</td>
			<td style="width:191px;">ThermoFisher Scientific</td>
			<td style="width:152px;">249944</td>
			<td>compatible with the Acquity UHPLC system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">T75&#160; cell culture flasks Corning</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td style="width:152px;">CLS430641&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Peelable heat sealing foil&#160;</td>
			<td style="width:191px;">Waters</td>
			<td style="width:152px;">186002789</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Acquity UPLC system</td>
			<td style="width:191px;">Waters</td>
			<td style="width:152px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Eppendorf Centrifuge 5810 R</td>
			<td style="width:191px;">Fisher Scientific</td>
			<td style="width:152px;">05-413-323</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Integration software: MassLynx V4.1</td>
			<td style="width:191px;">Waters</td>
			<td style="width:152px;"></td>
			<td>Catalog number not available</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Combi thermo-sealer SP-0669/240</td>
			<td style="width:191px;">Waters</td>
			<td style="width:152px;"></td>
			<td>Catalog number not available</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:271px;">Quattro micro API Tandem Quadrupole System</td>
			<td style="width:191px;">Waters</td>
			<td style="width:152px;"></td>
			<td>Catalog number not available</td>
		</tr>
	</tbody>
</table>

simultaneous measurement of hdac1 and hdac6 activity in hela cells using uhplc-ms

The search for new histone deacetylase (HDAC) inhibitors is of increasing interest in drug discovery. Isoform selectivity has been in the spotlight since the approval of romidepsin, a class I HDAC inhibitor for cancer therapy, and the clinical investigation of HDAC6-specific inhibitors for multiple myeloma. The present method is used to determine the inhibitory activity of test compounds on HDAC1 and HDAC6 in cells. The isoform activity is measured using the ultra-high-performance liquid chromatography &#8211; mass spectrometry (UHPLC-MS) analysis of specific substrates incubated with treated and untreated HeLa cells. The method has the advantage of reflecting the endogenous HDAC activity within the cell environment, in contrast to cell-free biochemical assays conducted on isolated isoforms. Moreover, because it is based on the quantification of synthetic substrates, the method does not require the antibody recognition of endogenous acetylated proteins. It is easily adaptable to several cell lines and an automated process. The method has already proved useful in finding HDAC6-selective compounds in neuroblasts. Representative results are shown here with the standard HDAC inhibitors trichostatin A (non-specific), MS275 (HDAC1-specific), and tubastatin A (HDAC6-specific) using HeLa cells.

To demonstrate the application of the method to identifying non-selective and selective inhibitors for HDAC1 (class I) and HDAC6 (class IIb), HeLa cells were treated with known standard compounds: trichostatin A (non-selective between HDAC1 and HDAC6)18, MS275 (HDAC1-selective inhibitor)19, and tubastatin A (HDAC6-selective inhibitor)20. By using the present method (Figure 1), IC50</...

Watch this Scientific Journal Video about Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS at JoVE.com

Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS

The present method serves to identify isoform-specific inhibitors of histone deacetylases (HDAC) in HeLa cells by the UHPLC-MS analysis of multiple substrates. This is an antibody-free method developed to reflect HDAC1 and HDAC6 activity in the living cell environment, in contrast to single-isoform cell-free assays.

The search for new histone deacetylase (HDAC) inhibitors is of increasing interest in drug discovery. Isoform selectivity has been in the spotlight since ...

The overall goal of this method is to determine the HDAC inhibitory potential of compounds and to identify selectivity towards HDAC6 or HDAC1 in cells using a single ultra high performance liquid chromatography mass spectrometry assay. This method can help answer key questions in the drug discovery field such as determining whether an HDAC inhibitor is selective for HDAC6 over Class I HDACs in living cells. The main advantage of this technique is that it requires a single incubation step with cells, inhibitors, and selective substrates in order to determine potency against two HDAC isoforms simultaneously.The implication of this technique extend toward early drug discovery of selective HDAC inhibitors because it detects whether HDAC6 selectivity is maintained in living cells avoiding endogenous protein acetylation assays. Though this method assesses selectivity of HDAC inhibitors in HeLa cells, it can also be applied to other cell lines such as primary and other tumor cells including clinical specimens. Culture HeLa cells to 80%confluency in a T75 cell culture flask in minimal essential media supplemented with 10%fetal bovine serum, penicillin G, and streptomycin.Wash the cells twice with five milliliters of Dulbecco's Phosphate-Buffered Saline. Then, aspirate the buffer and add one milliliter of cell dissociation reagent. Incubate at 37 degrees Celsius for five minutes to detach the cells.After five minutes, add nine milliliters of MEM culture medium to the cells and thoroughly resuspend the cell suspension. Transfer the cells to a new 15 milliliter tube and then count the cells using a hemocytometer. Adjust the density of the cell suspension to 60, 000 cells per milliliter in MEM.Next, add 100 microliters of the cell suspension to the control and test wells of a sterile, flat bottom, tissue culture treated 96 well plate. Then, add 100 microliters of MEM culture medium to the blank wells of the 96 well plate. Incubate the 96 well plate at 37 degrees Celsius for 24 hours.Aspirate the medium of the wells of the 96 well plate. While aspirating the medium, avoid detaching and removing cells from the well. This can be achieved by using a low aspiration rate and carefully placing the aspirating tips at the bottom corner of the well surface.Then, add 25 microliters of the two times test compounds in MEM to the test wells, including Trichostatin A, MS275, and Tubastatin A.Add 25 microliters of MEM to the control and blank wells. Next, add 25 microliters of the substrate mixture to the control and test wells. Then, add 25 microliters of MEM to the blank wells.Incubate the 96 well plate at 37 degrees Celsius for eight hours in a humidified 5%carbon dioxide incubator. To perform cell lysis, first add 10 microliters of six times RIPA buffer supplemented with protease inhibitor to each well of the 96 well plate. Stop the reaction by adding 160 microliters of cold acetonitrile to each well and mix by pipetting up and down.Place the plate in a minus 80 degrees Celsius freezer for 10 minutes. Remove the plate from the freezer and transfer 220 microliters of the content of each well to a non-sterile, conical bottom 96 well plate. Centrifuge the plate at 5, 000 times g and four degrees Celsius for 10 minutes.Following centrifugation, transfer 200 microliters of supernatant into a 96 well plate compatible with the UHPLC system. Then, seal the plate with peelable heat-sealing foil using a plate sealer. Prepare the ultra high performance liquid chromatography mass spectrometry system by filling it with the mobile phase system.Place the 96 well plate into a sample manager containing a plate holder. Run the samples according to the UHPLC ESI MS/MS conditions found in the text. To perform data analysis, integrate the peak area of each substrate and its deacetylated product with the appropriate UHPLC integration software.For each substrate, calculate the peak area ratio of deacetylated to acetylated in each chromatogram. Include the test and control samples. Finally, calculate the percent HDAC inhibition of each test sample according to the equation in the text protocol.The UHPLC-MS chromatogram of a sample is presented here. The peaks corresponding to the substrates added to the cells are detected according to their mass transitions as described in table one of the written protocol. MOCPAC is deacetylated by HDAC1 to provide the deacetylated MOCPAC peak.Similarly, BATCP is deacetylated by HDAC6 to provide the deacetylated BATCP peak. Finally, MAL provides the deacetylated MAL peak which reflects the deacetylation of several endogenous HDACs unspecifically. Shown here, the figure with the chromatogram obtained with different concentrations of the HDAC inhibitor Trichostatin A.A dose response evaluation of standard HDAC inhibitors was performed.The integrated values obtained from MOCPAC and dMOCPAC were used to calculate the potency of standard inhibitors against HDAC1. Following IC 50 calculations, MS275, a selective Class I HDAC inhibitor, showed lower IC 50 values for HDAC1 than Tubastatin A, a known HDAC6 inhibitor. On the other hand, the isolated values from BATCP and dBATCP were used to calculate the potency of the standards against HDAC6.This time, Tubastatin A provided a lower IC 50 value than MS275, confirming their isoform selectivity profile. Trichostatin A is a potent, nonselective inhibitor. Once mastered, this technique can be done in 72 hours if it's performed properly including the cell treatment time and the analysis of the 96 well plate.While attempting this procedure, it's important to remember that the incubation times indicated here are for HeLa cells. If another cell line is used, this needs to be optimized. Following this procedure, selective HDAC inhibitory activity of other isoforms could be measured as long as specific substrates exist.Don't forget that working with organic solvents and other chemicals can be extremely hazardous and protection glasses, gloves, and a lab coat should always be worn while performing this procedure.

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8.4K ビュー.  Universités des Geneva–Lausanne (EPGL). The overall goal of this method is to determine the HDAC inhibitory potential of compounds and to identify selectivity towards HDAC6 or HDAC1 in cells using a single ultra high performance liquid chromatography mass spectrometry assay. This method can help answer key questions in the drug discovery field such as determining whether an HDAC inhibitor is selective for HDAC6 over Class I HDACs in living cells. The main advantage of this technique is that it requires a single incubation step with...

ビデオ: Simultaneous Measurement of HDAC1 and HDAC6 Activity in HeLa Cells Using UHPLC-MS

Steady-state, Pre-steady-state, and Single-turnover Kinetic Measurement for DNA Glycosylase Activity

Human 8-oxoguanine DNA glycosylase (OGG1) excises the mutagenic oxidative DNA lesion 8-oxo-7,8-dihydroguanine (8-oxoG) from DNA. Kinetic characterization of OGG1 is undertaken to measure the rates of 8-oxoG excision and product release. When the OGG1 concentration is lower than substrate DNA, time courses of product formation are biphasic; a rapid exponential phase (i.e. burst) of product formation is followed by a linear steady-state phase. The initial burst of product formation corresponds to the concentration of enzyme properly engaged on the substrate, and the burst amplitude depends on the concentration of enzyme. The first-order rate constant of the burst corresponds to the intrinsic rate of 8-oxoG excision and the slower steady-state rate measures the rate of product release (product DNA dissociation rate constant, koff). Here, we describe steady-state, pre-steady-state, and single-turnover approaches to isolate and measure specific steps during OGG1 catalytic cycling. A fluorescent labeled lesion-containing oligonucleotide and purified OGG1 are used to facilitate precise kinetic measurements. Since low enzyme concentrations are used to make steady-state measurements, manual mixing of reagents and quenching of the reaction can be performed to ascertain the steady-state rate (koff). Additionally, extrapolation of the steady-state rate to a point on the ordinate at zero time indicates that a burst of product formation occurred during the first turnover (i.e. y-intercept is positive). The first-order rate constant of the exponential burst phase can be measured using a rapid mixing and quenching technique that examines the amount of product formed at short time intervals (&lt;1 sec) before the steady-state phase and corresponds to the rate of 8-oxoG excision (i.e. chemistry). The chemical step can also be measured using a single-turnover approach where catalytic cycling is prevented by saturating substrate DNA with enzyme (E&gt;S). These approaches can measure elementary rate constants that influence the efficiency of removal of a DNA lesion.

Time courses for the glycosylase activity of 8-oxoguanine DNA glycosylase are biphasic exhibiting a burst of product formation and a linear steady-state phase. Utilizing quench-flow techniques, the burst and the steady-state rates can be measured, which correspond to excision of 8-oxoguanine and release of the glycosylase from the product DNA, respectively.

Human 8-oxoguanine DNA glycosylase (OGG1) excises the mutagenic oxidative DNA lesion 8-oxo-7,8-dihydroguanine (8-oxoG) from DNA. Kinetic characterization ...

A Simple and Rapid Protocol for Measuring Neutral Lipids in Algal Cells Using Fluorescence

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal fermentation processes and screening for new oil-rich strains requires a fast and reliable protocol for determination of intracellular lipid content. Current practices rely largely on gravimetric methods to determine oil content, techniques developed decades ago that are time consuming and require large sample volumes. In this paper, Nile Red, a fluorescent dye that has been used to identify the presence of lipid bodies in numerous types of organisms, is incorporated into a simple, fast, and reliable protocol for measuring the neutral lipid content of Auxenochlorella protothecoides, a green alga. The method uses ethanol, a relatively mild solvent, to permeabilize the cell membrane before staining and a 96 well micro-plate to increase sample capacity during fluorescence intensity measurements. It has been designed with the specific application of monitoring bioprocess performance. Previously dried samples or live samples from a growing culture can be used in the assay.

A simple protocol to determine the neutral lipid content of algal cells using a Nile Red staining procedure is described. This time-saving technique offers an alternative to traditional gravimetric-based lipid quantification protocols. It has been designed for the specific application of monitoring bioprocess performance.

Algae are considered excellent candidates for renewable fuel sources due to their natural lipid storage capabilities. Robust monitoring of algal ...

HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2&#8217;-deoxyguanosine, in Cultured Cells and Animal Tissues

Oxidative stress is associated with many physiological and pathological processes, as well as xenobiotic metabolism, leading to the oxidation of biomacromolecules, including DNA. Therefore, efficient detection of DNA oxidation is important for a variety of research disciplines, including medicine and toxicology. A common biomarker of oxidatively damaged DNA is 8-oxo-7,8-dihydro-2&#39;-deoxyguanosine (8-oxo-dGuo; often erroneously referred to as 8-hydroxy-2&#39;-deoxyguanosine (8-OH-dGuo or 8-oxo-dG)). Several protocols for 8-oxo-dGuo measurement by high pressure liquid chromatography with electrochemical detection (HPLC-ED) have been described. However, these were mainly applied to purified DNA treated with pro-oxidants. In addition, due to methodological differences between laboratories, mainly due to differences in analytical equipment, the adoption of published methods for detection of 8-oxo-dGuo by HPLC-ED requires careful optimization by each laboratory. A comprehensive protocol, describing such an optimization process, is lacking. Here, a detailed protocol is described for the detection of 8-oxo-dGuo by HPLC-ED, in DNA from cultured cells or animal tissues. It illustrates how DNA sample preparation can be easily and rapidly optimized to minimize undesirable DNA oxidation that can occur during sample preparation. This protocol shows how to detect 8-oxo-dGuo in cultured human alveolar adenocarcinoma cells (i.e., A549 cells) treated with the oxidizing agent KBrO3, and from the spleen of mice exposed to the polycyclic aromatic hydrocarbon dibenzo(def,p)chrysene (DBC, formerly known as dibenzo(a,l)pyrene, DalP). Overall, this work illustrates how an HPLC-ED methodology can be readily optimized for the detection of 8-oxo-dGuo in biological samples.

HPLC Measurement of the DNA Oxidation Biomarker, 8-oxo-7,8-dihydro-2&amp;#8217;-deoxyguanosine, in Cultured Cells and Animal Tissues

The goal of this protocol is the detection of the DNA oxidation marker, 8-oxo-7,8-dihydro-2&#39;-deoxyguanosine (8-oxo-dGuo) by HPLC-ED, in DNA from cultured cells or animal tissues.

Oxidative stress is associated with many physiological and pathological processes, as well as xenobiotic metabolism, leading to the oxidation of ...

Dynamic Electrochemical Measurement of Chloride Ions

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement, long-term and continuous monitoring is limited due to the inherent drift and the requirement of a stable reference electrode. We utilized the chronopotentiometric approach to minimize drift and avoid the use of a conventional reference electrode. A galvanostatic pulse is applied to an Ag/AgCl electrode which initiates a faradic reaction depleting the Cl&#713; ions near the electrode surface. The transition time, which is the time to completely deplete the ions near the electrode surface, is a function of the ion concentration, given by the Nernst equation. The square root of the transition time is in linear relation to the chloride ion concentration. Drift of the response over two weeks is negligible (59 &#181;M/day) when measuring 1 mM [Cl&#713;]using a current pulse of 10 Am-2. This is a dynamic measurement where the moment of transition time determines the response and thus is independent of the absolute potential. Any metal wire can be used as a pseudo-reference electrode, making this approach feasible for long-term measurement inside concrete structures.

Dynamic measurement of chloride ions is presented. Transition time of an Ag/AgCl electrode, during a chronopotentiometric technique, can give the concentration of chloride ions in electrolyte. This method does not require a stable conventional reference electrode.

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver ...

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical (Methylation) and Physical (Mass Spectrometry, Nuclear Magnetic Resonance) Techniques

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans. De-starched wheat endosperm cell walls were isolated as an alcohol-insoluble residue (AIR)1 and sequentially extracted with water (W-sol Fr) and 1 M KOH containing 1% NaBH4 (KOH-sol Fr) as described by Ratnayake et al. (2014)2. Two different approaches (see summary in Figure 1) are adopted. In the first, intact W-sol AXs are treated with 2AB to tag the original RE backbone chain sugar residue and then treated with an endoxylanase to generate a mixture of 2AB-labelled RE and internal region reducing oligosaccharides, respectively. In a second approach, the KOH-sol Fr is hydrolyzed with endoxylanase to first generate a mixture of oligosaccharides which are subsequently labelled with 2AB. The enzymically released ((un)tagged) oligosaccharides from both W- and KOH-sol Frs are then methylated and the detailed structural analysis of both the native and methylated oligosaccharides is performed using a combination of MALDI-TOF-MS, RP-HPLC-ESI-QTOF-MS and ESI-MSn. Endoxylanase digested KOH-sol AXs are also characterized by nuclear magnetic resonance (NMR) that also provides information on the anomeric configuration. These techniques can be applied to other classes of polysaccharides using the appropriate endo-hydrolases.

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical Methylation and Physical Mass Spectrometry, Nuclear Magnetic Resonance Techniques

This protocol describes the specific techniques used for the structural characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans by tagging the RE with 2 aminobenzamide prior to enzymatic (endoxylanase) hydrolysis and then analysis of the resultant oligosaccharides using mass spectrometry (MS) and nuclear magnetic resonance (NMR).

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

High Resolution Physical Characterization of Single Metallic Nanoparticles

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single nanometer-scale pore. The signal is characteristic of the molecule&#39;s physicochemical properties and its interactions with the pore. We demonstrate that the nanopore formed by the bacterial protein exotoxin Staphylococcus aureus alpha hemolysin (&#945;HL) can detect polyoxometalates (POMs, anionic metal oxygen clusters), at the single molecule limit. Moreover, multiple degradation products of 12-phosphotungstic acid POM (PTA, H3PW12O40) in solution are simultaneously measured. The single molecule sensitivity of the nanopore method allows for POMs to be characterized at significantly lower concentrations than required for nuclear magnetic resonance (NMR) spectroscopy. This technique could serve as a new tool for chemists to study the molecular properties of polyoxometalates or other metallic clusters, to better understand POM synthetic processes, and possibly improve their yield. Hypothetically, the location of a given atom, or the rotation of a fragment in the molecule, and the metal oxidation state could be investigated with this method. In addition, this new technique has the advantage of allowing the real-time monitoring of molecules in solution.&#160;

Here, we present a protocol to detect discrete metal oxygen clusters, polyoxometalates (POMs), at the single molecule limit using a biological nanopore-based electronic platform. The method provides a complementary approach to traditional analytical chemistry tools used in the study of these molecules.

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single ...

A New Straightforward Method for Lipophilicity (logP) Measurement using 19F NMR Spectroscopy

Fluorination has become an effective tool to optimize physicochemical properties of bioactive compounds. One of the applications of fluorine introduction is to modulate the lipophilicity of the compound. In our group, we are interested in the study of the impact of fluorination on lipophilicity of aliphatic fluorohydrins and fluorinated carbohydrates. These are not UV-active, resulting in a challenging lipophilicity determination. Here, we present a straightforward method for the measurement of lipophilicity of fluorinated compounds by 19F NMR spectroscopy. This method requires no UV-activity. Accurate solute mass, solvent and aliquot volume are also not required to be measured. Using this method, we measured the lipophilicities of a large number of fluorinated alkanols and carbohydrates.

A New Straightforward Method for Lipophilicity logP Measurement using 19F NMR Spectroscopy

A novel and straightforward variation of the shake-flask method was developed for accurate lipophilicity measurement of fluorinated compounds by 19F NMR spectroscopy.

Fluorination has become an effective tool to optimize physicochemical properties of bioactive compounds. One of the applications of fluorine introduction ...

NMR-Based Activity Assays for Determining Compound Inhibition, IC50 Values, Artifactual Activity, and Whole-Cell Activity of Nucleoside Ribohydrolases

NMR spectroscopy is often used for the identification and characterization of enzyme inhibitors in drug discovery, particularly in the context of fragment screening. NMR-based activity assays are ideally suited to work at the higher concentrations of test compounds required to detect these weaker inhibitors. The dynamic range and chemical shift dispersion in an NMR experiment can easily resolve resonances from substrate, product, and test compounds. This contrasts with spectrophotometric assays, in which read-out interference problems often arise from compounds with overlapping UV-vis absorption profiles. In addition, since they lack reporter enzymes, the single-enzyme NMR assays are not prone to coupled-assay false positives. This attribute makes them useful as orthogonal assays, complementing traditional high throughput screening assays and benchtop triage assays. Detailed protocols are provided for initial compound assays at 500 &#956;M and 250 &#956;M, dose-response assays for determining IC50 values, detergent counter screen assays, jump-dilution counter screen assays, and assays in E. coli whole cells. The methods are demonstrated using two nucleoside ribohydrolase enzymes. The use of 1H NMR is shown for the purine-specific enzyme, while 19F NMR is shown for the pyrimidine-specific enzyme. The protocols are generally applicable to any enzyme where substrate and product resonances can be observed and distinguished by NMR spectroscopy. To be the most useful in the context of drug discovery, the final concentration of substrate should be no more than 2-3x its Km value. The choice of NMR experiment depends on the enzyme reaction and substrates available as well as available NMR instrumentation.

NMR-Based Activity Assays for Determining Compound Inhibition, IC50 Values, Artifactual Activity, and Whole-Cell Activity of Nucleoside Ribohydrolases

NMR-based activity assays have been developed to identify and characterize inhibitors of two nucleoside ribohydrolase enzymes. Protocols are provided for initial compound assays at 500 &#956;M and 250 &#956;M, dose-response assays for determining IC50 values, detergent counter screen assays, jump-dilution counter screen assays, and assays in E. coli whole cells.

NMR spectroscopy is often used for the identification and characterization of enzyme inhibitors in drug discovery, particularly in the context of fragment ...