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Calibration of a mass spectrometry protocol for dental calculus protein analysis

ABSTRACT: Protein Processing: Following protein precipitation, samples underwent reduction by adding Dithiothreitol (Merck) to a final concentration of 10mM for 60 min at 55C, followed by alkylation by adding Iodoacetamide (Merck) to a final concentration of 18.75 mM for 30 minutes at room temperature. Subsequently, samples were digested overnight at 37C with 10 nG MS Grade Trypsin (Promega). Trypsinization was quenched with 1 uL of 0.1% Trifluoroacetic acid (TFA) (ThermoFisher). Solid Phase Extraction Stage Tips for Detergent Removal: Prior to mass spectrometry, samples were cleaned with a solid phase extraction method using 2 layers of C18 Empore SPE Disks (Merck) followed by 2 layers of SCX strong cation exchange Empore SPE Disks (Merck). Samples were then lyophilized . MS analysis: MS analysis was performed at the National Proteomics Unit at the Technion, Israel. The peptides were resolved by reverse-phase chromatography on 0.075 X 300-mm fused silica capillaries packed with Reprosil reversed phase material (Dr Maisch GmbH, Germany). The peptides were eluted using a linear 60 or 120 minutes gradient of 5 to 28%, a 15 minutes gradient of 28 to 95%, and 15 minutes at 95% Acetonitrile with 0.1% formic acid in water at flow rates of 0.15 u/min. MS analysis was performed by Q Exactive HF mass spectrometer (Thermo) in a positive mode (m/z 300-1800, resolution 120,000 for MS1 and 15,000 for MS2) using repetitively full MS scan followed by high collision dissociation (HCD, at 27 normalized collision energy) of the 20 most dominant ions (>=1 charges) selected from the first MS scan. The AGC settings were 3x10 6 for the full MS and 1x10 5 for the MS/MS scans. The intensity threshold for triggering MS/MS analysis was 1.3x10 5. A dynamic exclusion list was enabled with exclusion duration of 20s.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Escherichia Coli (ncbitaxon:562) Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Daniel Bar

PROVIDER: MSV000090092 | MassIVE | Sun Aug 07 05:39:00 BST 2022

REPOSITORIES: MassIVE

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Project description:Proper sample preparation protocols represent a critical step for LC-MS-based proteomic study designs and influence the speed, performance and automation of high-throughput data acquisition. The main objective of this study was to compare two commercial solid phase extraction (SPE)-based sample preparation protocols (comprising SOLAµTM HRP SPE spin plates from Thermo Fisher Scientific and ZIPTIP® C18 pipette tips from Merck Millipore) for analytical performance, reproducibility and analysis speed. The house swine represents a promising animal model for studying human eye diseases including glaucoma and provides excellent requirements for the qualitative and quantitative MS-based comparison in terms of ocular proteomics. In total 6 technical replicates of two protein fractions [extracted with 0.1% dodecyl-ß-maltoside (DDM) or 1% trifluoroacetic acid (TFA)] of porcine retinal tissues were subjected to in-gel trypsin digestion and purified with both SPE-based workflows (N=3) prior to LC-MS analysis. On average, 550±70 proteins (1512±199 peptides) and 305±48 proteins (806±144 peptides) were identified from DDM and TFA protein fractions, respectively, after ZIPTIP® purification, and SOLAµTM workflow resulted in the detection of 513±55 proteins (1347±180 peptides) and 300±33 proteins (722±87 peptides), respectively (FDR<1%). Venn diagram analysis revealed an average overlap of 65±2% (DDM fraction) and 69±4% (TFA fraction) in protein identifications between both SPE-based methods. Quantitative analysis of 25 glaucoma-related protein markers also showed no significant differences (P>0.05) regarding protein recovery between both SPE methods. However, only glaucoma-associated marker MECP2 showed a significant (P=0.02) higher abundance in ZIPTIP®-purified replicates in comparison to SOLAµTM-treated study samples. Nevertheless, this result was not confirmed in the verification experiment using in-gel trypsin digestion of recombinant MECP2 (P=0.24). In conclusion, both SPE-based purification methods worked equally well in terms of analytical performance and reproducibility, whereas the analysis speed and the semi automation of the SOLAµTM spin plates workflow is much more convenient in comparison to the ZIPTIP® C18 method.

Project description:Growth factor signaling and angiogenesis may promote endocrine-resistance in breast cancer and blocking these pathways can overcome resistance in preclinical models. We conducted a phase-II study of adding the VEGFR/Ras/Raf/MAPK inhibitor sorafenib to endocrine therapy in metastatic ER-positive breast cancer, either upon progression or after maximal response with measurable residual disease. Tumor biopsies and serum were collected on days 1 and 28. Primary endpoint was response by RECIST after 3 months and secondary endpoints included safety, time to progression (TTP), and biomarker assessment. Planned sample size was 43 patients but the study closed after 11 patients because of slow accrual. 8 patients had progressive disease (PD) on entry and 3 had stable disease (SD). One patient with SD discontinued sorafenib after 2-weeks because of grade 3 rash. Of the 10 remaining patients after adding sorafenib, 7 had SD (70%), 3 had PD (30%) and median TTP was 6.1-months. Of the 8 patients who entered the study with PD on endocrine therapy, 5 converted to SD (62%) with a median TTP of 6.4-months. Notably, patients on tamoxifen had a median TTP of 8.4-months. The most common adverse events were hypophosphatemia, hypokalemia, and rash, and the majority were grade 1&2 with no grade 4 toxicities. There was a significant reduction in serum VEGFR2 and PDGFR-α on day-28 (p-values 0.0035 and 0.017, respectively). Both serum VEGF and sVEGFR-1 were increased on day-28, but the differences were not statistically significant (p-values 0.3223 and 0.084, respectively). Microarray analysis identified 32 suppressed genes with an FDR of <0.20 and at least a 2-fold change with no induced genes and 29 KEGG pathways were enriched on day-28. Our study suggests that sorafenib can restore endocrine sensitivity, particularly tamoxifen, and this strategy of adding novel agents in patients progressing on endocrine therapy should be examined in future trials. This was a single-institution, phase II study of adding sorafenib to existing endocrine therapy. On study entry, eligible patients underwent serum sample collection and core biopsy of accessible disease (if applicable) on endocrine therapy and prior to starting sorafenib. Serum and a second biopsy were then collected on day 28. Sorafenib dose was 400mg orally twice daily along with continuing the same endocrine agent. Patients were followed monthly for clinical and toxicity evaluation. Disease response by RECIST criteria was assessed after 3 months by appropriate scans and these were obtained every 2 months thereafter until progression. Sorafenib and the endocrine agent were continued until disease progression or unacceptable toxicity

Project description:One milliliter of triplicate bacterial cultures in both Wild type (WT) and rpoN mutant were immediately pelleted by centrifugation at 9000 rpm at room temperature for 2 minutes after adding phenol:ethanol. The supernatant were removed and the pellets resuspended in 0.5 ml Trizol solution. For Gram-negative bacteria, the cells were homogenized in Trizol solution by pipetting up and down 15 times. For Gram-positive bacteria, culture suspensions in Trizol were transferred to previously cooled bead beater tubes containing 0.1-mm glass beads and treated with Mini-Beadbeater (Biospec Products Inc, USA) twice at a fixed speed for 45 seconds, and then cooled on ice for 1 minute between the treatments. Culture homogenates were incubated at room temperature for 5 minutes and then supplemented with 0.2 ml chloroform, thoroughly mixed by shaking 10 times, and incubated for 3 minutes. After centrifugation at 12 000 g at 4°C for 15 minutes, the aqueous upper phase was carefully transferred to new RNase free tubes. An equal volume of 99% ethanol was added to the transferred aqueous phase and isolation continued using the Direct-Zol RNA Miniprep Plus (Zymo Research, USA) RNA purification kit protocol. Total RNAs were eluted in RNase free water in RNase free tubes. The total RNA concentrations were measured using the Qubit BR RNA Assay Kit (ThermoFisher Scientific, USA) and RNA integrity confirmed on a 0.8% agarose gel in TBE buffer. All rRNA-depleted RNA-seq library preparations were performed according to Shishkin et al.,2015 with minor modifications. RNAtag-Seq allows multiple library preparations in one tube, with initial tagging of total RNA samples with modified (5'P and 3'ddC) DNA barcoded adaptors, each harboring a unique 8 nt sequence used to demultiplex individual libraries after sequencing We combined the library preparation of three biological replicates from WT and ∆rpon preparations in one tube for each bacterial strain. Therefore, 24 unique barcoded adaptors were used to tag the 24 replicates. A total of 100 ng total RNA was used for each biological replicate. The total RNA was fragmented in 2X FastAP Thermosensitive Alkaline Phosphatase buffer for 3 minutes at 94°C, DNase treated, and dephosphorylated with a combination of TURBO DNase and Thermosensitive Alkaline Phosphatase in 1X FastAP buffer for 30 minutes at 37°C. Fragmented, DNase-treated, and dephosphorylated total RNAs were cleaned with a 2X reaction volume of Agencourt RNAClean XP beads. Cleaned total RNAs were incubated with 100 pmol of a unique DNA barcode adaptor at 70°C for 3 minutes, and then ligated with T4 RNA ligase 1 for 90 minutes at 22°C. The ligation was stopped and the enzyme denatured by the addition of RLT buffer. The 36 denatured ligation mixes were then pooled and cleaned in a Zymo Clean & ConcentratorTM-5 column according to the manufacturer's 200 nt cut-off protocol. The RNAs were eluted in 32 ml of RNase free water. The ribosomal RNA was depleted using the Ribo-ZeroTM Magnetic Gold Kit (Bacteria) according to the manufacturer's instructions. The first strand cDNA of each pool was generated using an AffinityScript Multiple Temperature cDNA synthesis kit with 50 pmol of AR2 primer at 55°C for 55 minutes. The RNA was degraded by adding a 10% reaction volume of 1 N NaOH at 70°C for 12 minutes and the reaction neutralized with an 18% reaction volume of 0.5 M acetic acid. After cleaning the reverse transcription primers with a 2X reaction volume of RNAClean XP beads, the 3Tr3 adapter was ligated with T4 RNA ligase 1 at 22°C with overnight incubation. The second ligation was cleaned first with a 2X, and secondly 1.5X, reaction volume of RNAClean XP beads. The cDNA was then used as the template for PCR reaction with FailSafeTM PCR enzyme mix using 12.5 pmol 2P_univP5 as forward primers and 12.5 pmol ScriptSeqTM Index (barcode) PCR primers as reverse primers. The PCR cycles were as follows: 95°C for 3 minutes, followed by 12 cycles at 95°C for 30 seconds, 55°C for 30 seconds, and 68°C for 3 minutes, and then finishing at 68°C for 7 minutes. The PCR product was cleaned first with a 1.5X, and secondly 0.8X, reaction volume of AMPure beads and eluted in RNAse free water. The library concentrations were measured using the QubitTM dsDNA HS Assay Kit and the library insert size determined by the Agilent DNA 1000 Kit in a 2100 Electrophoresis Bioanalyser Instrument (Agilent, USA). The libraries were sequenced by Illumina NovaSeq 6000

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Calibration of a mass spectrometry protocol for dental calculus protein analysis

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