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Quantitative phosphoproteomics for studying B-cell receptor signaling in Burkitt’s lymphoma

dc.contributor.advisorUrlaub, Henning Prof. Dr.
dc.contributor.authorCorso, Jasmin
dc.titleQuantitative phosphoproteomics for studying B-cell receptor signaling in Burkitt’s lymphomade
dc.contributor.refereeUrlaub, Henning Prof. Dr.
dc.description.abstractengProtein phosphorylation plays an important role in transmitting cellular signals. Phosphorylation has been mostly characterized by hypothesis-driven and low-throughput approaches in the past. However, novel phosphorylation sites on not yet identified signaling effectors involved in cellular responses can only be investigated in an unbiased and large-scale manner. The global investigation of phosphorylation processes in a cellular system can help to understand signaling that drives malignant transformation of cells. Moreover, phosphorylation patterns might hint towards potential therapeutic targets e.g. activated kinases. The generation and analysis of large-scale PTM datasets was made feasible by improved enrichment protocols in combination with the fast evolution of high resolution, quantitative mass spectrometry, computational approaches, and functional databases. The data presented in this thesis comprises three large-scale phosphoproteomics projects. The main project represents the investigation of antigen-dependent and tonic BCR signaling in Burkitt’s lymphoma (BL). As antigen-dependent BCR signaling in BL has not yet been described, phosphorylation changes were investigated in a time-resolved manner in DG75 cells and additionally in two other BL models including one primary BL cell culture. Overall, the MS-based antigen-dependent signaling analyses lead to the identification of thousands of altered phosphorylation sites upon BCR engagement in DG75. Based on this data, a higher order organization structure was extracted, complemented with database information and mapped to datasets derived from RNAseq, kinobead and kinase inhibition analyses. Signaling in BL cells was found to be highly individual in different cell lines. Tonic BCR signaling was investigated upon knockdown of the BCR signaling molecule CD79A and by inhibition of the receptor-proximal tyrosine kinase SYK. Comparison of the antigen-independent and -dependent BCR signaling phosphoproteomes revealed substantial differences as well as certain similarities of both processes. The second project focused on the analysis of global phosphorylation dynamics in acute myeloid leukemia (AML) after BTK inhibition. As BTK was identified as an activated kinase in AML, the mechanism of its activation and the influence of BTK ablation were investigated in two AML cell lines with different genetic backgrounds. Phosphoproteomic changes observed upon BTK inhibition highlighted individual differences and similarities of BTK action and identified relevant upstream activators of BTK as well as downstream effector proteins in AML cells. The third project was aimed at profiling the phosphorylation site dynamics of the TCR adapter proteins LCP2 (SLP76) and GADS (GRAP2) in time-resolved TCR stimulation. The dynamics of several phosphorylation sites could be captured over a time course, and provide a basis for further functional characterization by e.g. mutation of p-sites. In summary, this work globally characterized phosphorylation changes upon different cellular conditions by quantitative mass spectrometry-based phosphoproteomics and provides a basis for the identification of druggable proteins or yet unknown signaling
dc.contributor.coRefereeJahn, Reinhard Prof. Dr.
dc.contributor.thirdRefereeBernhard, Küster Prof. Dr.
dc.subject.engBCR signalingde
dc.subject.engMass spectrometry-based proteomicsde
dc.affiliation.instituteGöttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB)de
dc.subject.gokfullBiologie (PPN619462639)de

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