Project description:We have simulated a carrier proteome effect using a two-proteome quantitative TMTPro 9-plex labeled sample series to evaluate the effects of extreme carrier channels on TIMSTOF quantification.
Project description:Single cell proteomics by mass spectrometry (SCoPE-MS) is a recently introduced method that utilizes isobaric labels to quantify multiplexed single cell proteomes. While this technique has generated great excitement, the technologies underlying SCoPE-MS - isobaric labels and mass spectrometry - comprise technical limitations with the potential to unfavorably impact data quality and biological interpretation. These limitations are due to the carrier proteome, a sample added at 25-500x single cell proteomes to enable peptide identifications. Here, we perform SCoPE-MS experiments with increasing amounts of carrier proteome and evaluate quantitative accuracy as it relates to mass analyzer dynamic range, multiplexing level, and number of ions sampled. We demonstrate that an increase in carrier proteome level requires a concomitant increase in the number of ions sampled to maintain quantitative accuracy – we term this the carrier proteome effect. Based on our findings, we provide guidance on experimental design, data collection, and data analysis to limit the impact of the carrier proteome effect within SCoPE-MS measurements.
Project description:Single cell proteomics by mass spectrometry (SCoPE-MS) is a recently introduced method to quantify multiplexed single cell proteomes. While this technique has generated great excitement, the underlying technologies (isobaric labeling and mass spectrometry) comprise technical limitations with the potential to effect data quality and biological interpretation. These limitations are particularly relevant when a carrier proteome, a sample added at 25-500x single cell proteomes, is used to enable peptide identifications. Here, we perform controlled experiments with increasing carrier proteome amounts and evaluate quantitative accuracy as it relates to mass analyzer dynamic range, multiplexing level, and number of ions sampled. We demonstrate that an increase in carrier proteome level requires a concomitant increase in the number of ions sampled to maintain quantitative accuracy. Lastly, we introduce Single Cell Proteomics Companion a program that enables rapid evaluation of single cell proteomics data and recommends instrument and data analysis parameters for improved data quality.
Project description:We probe the carrier proteome effects in single cell proteomics with mixed species TMTpro-labeled samples. We demonstrate that carrier proteomes, while increasing overall identifications, dictate which proteins are identified. We show that quantitative precision and signal intensity are limited at high carrier levels, hindering the recognition of regulated proteins. Guidelines for optimized mass spectrometry acquisition parameters and best practices for fold-change or protein copy number-based comparisons are provided.
Project description:Multiplexed single cell proteomics by mass spectrometry (scpMS) approaches currently offer the highest throughput as measured by cells analyzed per day. These methods employ isobaric labels and typically a carrier proteome - a sample added at 20-500x the single cell level that improves peptide sampling and identification. Peptides from the carrier and single cell proteomes exist within the same precursor isotopic cluster and are co-isolated for identification and quantification. This represents a challenge as high levels of carrier proteome limit the sampling of peptide ions from single cell samples and can potentially lead to decreased accuracy of quantitative measurements. Here, we address this limitation by introducing a triggered by offset mass acquisition method for scpMS (toma-scpMS) that utilizes a carrier proteome labeled with non-isobaric tags that have the same chemical composition but different mass as the labels used for quantitative multiplexing. Within toma-scpMS the carrier proteome and single cell proteome are separated at the precursor level, enabling separate isolation, fragmentation, and quantitation of the single cell samples. To enable this workflow we implemented a custom data acquisition scheme within inSeqAPI, an instrument application programming interface program, that performed real-time identification of carrier proteome peptides and subsequent triggering of offset single cell quantification scans. We demonstrate that toma-scpMS is more robust to high-levels of carrier proteome and offers superior quantitative accuracy as compared to traditional multiplexed scpMS approaches when similar carrier proteome levels are employed.
Project description:Streptococcus equi subsp. equi (SEE) is a host-restricted bacterium that causes the common infectious upper respiratory disease known as strangles in horses. Perpetuation of SEE infection appears attributable to inapparent carrier horses because it does not persist long-term in the environment, infect other host mammals or vectors, and result in short-lived immunity. Whether pathogen factors enable SEE to remain in horses without causing clinical signs remains poorly understood. Thus, our objective was to use next-generation sequencing technologies to characterize the transcriptome of isolates of SEE from horses with acute clinical strangles and inapparent carrier horses to assess pathogen-associated changes that might reflect adaptions of SEE to the host contributing to inapparent carriage. RNA sequencing of SEE isolates from Pennsylvania demonstrated no genes that were differentially expressed between acute clinical and inapparent carrier isolates of SEE.
Project description:Loss of the mitochondrial pyruvate carrier promotes stem cell gene expression in AOMDSS colon adenomas, though loss of Apc promotes a more unified pehnotype.