Project description:Methanococcus maripaludis is a methanogenic archaeon. Within its genome, there are two operons for membrane associated hydrogenases, eha and ehb. To investigate the regulation of ehb on the cell, an S40 mutant was constructed in such a way that a portion of the ehb operon was replaced by pac cassette in the wild type parental strain S2 (done by Whitman's group at the University of Georgia). The S40 and S2 strains were grown in 14N and 15N media with acetate separately. A biological replicate was made by switching the media. Mass spectrometry based quantitative proteomics were done on the mixtures to investigate the differences in expression patterns between S40 and S2. Keywords: isotope labeling mass spectrometry, quantitative proteomics
Project description:The challenge of discovering a completely new human tumor virus of unknown phylogeny or sequence depends on detecting viral molecules and differentiating them from host-derived molecules in the virus-associated neoplasm. We developed differential peptide subtraction (DPS) using differential mass-spectrometry (dMS) followed by targeted analysis to facilitate this discovery. To trace the non-human dMS identified peptides back to its genetic origin by next generation sequencing (NGS) cDNA libraries were generated using degenerate oligos corresponding to the identified peptides. In a pilot study DPS identified both viral and human biomarkers. Based on the identified peptides that are differentially expressed in the virus positive tumor sample, degenerate oligos were designed. Degenerate oligos or LNA modified degenerate oligos or a modified oligo(dT) SMART primer were used to facilitate reverse transcription from viral or viral and host RNA. NGS analysis revealed seven times more MCV reads in degenerate oligo primed RNAseq samples compared to polyA-based sequencing reads.
Project description:We report the usage of ChIP-mass spectrometry in identifying proteins and histone modifications involved in Drosophila dosage compensation. We identified a chromatin targeting factor, CG4747, that is involved in recognition of H3K36me3 and robust recruitment of the Drosophila MSL complex to its correct targets on the male X chromosome. ChIP-seq with PAP antibody of Drosophila larvae expressing C-terminally TAP-tagged CG4747.
Project description:The vascular endothelial growth factor A (VEGF) is involved in various physiological processes such as angiogenesis or wound healing but is also crucial in pathological events such as tumor growth. Thus, clinical anti-VEGF treatments have been developed which could already prove to have enormous beneficial effects for cancer patients. In this article we describe the first VEGF-derived CD8+ T-cell epitope. The natural HLA ligand SRFGGAVVR was identified by differential mass spectrometry in two primary renal cell carcinomas (RCC) and was significantly over-presented on both tumor tissues. SRFGGAVVR is derived from a cryptic translated region of VEGF presumably by initiation of translation at the non-classical start codon CUG499. SRFGGAVVR specific T-cells were generated in vitro using peptide loaded dendritic cells or artificial antigen presenting cells. They were identified by HLA tetramer analysis after in vitro stimulation. SRFGGAVVR specific CD8+ T-cells were fully functional T-effector cells, which were able to secrete IFN-gamma upon stimulation and killed tumor cells in vitro. Additionally, we have quantitatively analyzed VEGF mRNA and protein levels in RCC tumor and normal tissue samples by gene chip analysis, qRT-PCR, in situ hybridization, and bead based immuno assay. In the future, T-cells directed against VEGF as a tumor associated antigen may represent a possible way of combining peptide-based anti-VEGF immunotherapy with already existent anti-VEGF cancer therapies. Keywords: disease state analysis
Project description:More than half of the mass spectra could not be identified in most proteome mass spectrometry experiments. Various modifications have been considered as a major reason. Open search strategy was then introduced to solve this problem, however, lacking thorough quality assessment using independent information. Here, we used the “Suspicious Discovery Rate (SDR)” based on the translatome sequencing (RNC-seq) as an independent source to assess the proteome open search strategy. We found that the open search strategy increased the spectra utilization with the cost of increasing suspicious identifications that lacks translation evidence. We further suggested that restricting the peptide FDR below 0.1% would efficiently control the suspicious identifications of open search methods and enhanced the confidence of the peptide identification with modifications than the narrow window search. These results facilitated the proper use of open search methods for higher quality of proteome identifications with the information of post-translational modifications and single amino acid polymorphisms
Project description:Matrix-assisted laser desorption/ionization mass spectrometry imaging allows for the study of metabolic activity in the tumor microenvironment of brain cancers. The detectable metabolites within these tumors are contingent upon the choice of matrix, deposition technique, and polarity setting. In this study, we compared the performance of three different matrices, two deposition techniques, and the use of positive and negative polarity in two different brain cancer types and across two species. Optimal combinations were confirmed by a comparative analysis of lipid and small-molecule abundance by using liquid chromatography-mass spectrometry and RNA sequencing to assess differential metabolites and enzymes between normal and tumor regions. Our findings indicate that in the tumor-bearing brain, the recrystallized α-cyano-4-hydroxycinnamic acid matrix with positive polarity offered superior performance for both detected metabolites and consistency with other techniques. Beyond these implications for brain cancer, our work establishes a workflow to identify optimal matrices for spatial metabolomics studies.
Project description:To understand the functional roles of YTHDF1 in cellular senescence and aging, we lead the RNA sequence in WT or Ythdf1 deficiency colon epithelial cells. The results showed that the cholesterol biosynthesis related genes were upregulated in Ythdf1 KO mice. We also purified FLAG-YTHDF1 protein in HEK293T cells and did protein mass spectrometry, and found that the mTORC1 and TSC complex constituents mTOR, RPTOR, and TSC1/2 were identified in the YTHDF1-complex. Methylated RNA immunoprecipitation(MeRIP) with specific m6A antibody and used for library construction and the next generation sequencing, to identify m6A modified transcripts in WT or Ythdf1 deficiency colon epithelial cells after DSS treatment