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Biomedical subjects

Dorothea Rutishauser

Publications and source records attributed to Dorothea Rutishauser.

4 recordsLinked to original sources

Deep visual multi-omics profiling links morphology and molecular programs in clear cell renal cell carcinoma.

Clear cell renal cell carcinoma exhibits striking intra-tumoral heterogeneity at morphological and genetic levels, complicating treatment and contributing to disease progression. CcRCCs with rhabdoid differentiation are highly aggressive tumors characterized by distinct histopathologies. However, the relationship between morphology, underlying molecular alterations, and tumor behavior remains largely unclear. Here, we present Deep Visual Multi-Omics, an approach integrating digital pathology, morphology-guided single-cell isolation, and ultra-sensitive multi-omics profiling to link cell morphologies to their molecular underpinnings. Across five tumors, we profiled ~40,000 AI-classified and expert-curated cells. We identified progressive molecular dysregulation across cells with increasing histopathological grade coexisting within heterogeneous tumors as well as distinct molecular alterations associated with aggressive rhabdoid ccRCC cells, including signatures consistent with enhanced FOXM1-driven proliferation, altered cell-matrix interactions, and a putative immunomodulatory phenotype. Notably, rhabdoid cells exhibited elevated expression of IFN-beta, PD-L1, CD38, ITGB2, and integrin signaling, suggesting that they themselves may act as a source of signals influencing the local immune microenvironment. Besides providing new insights into the biology of ccRCC and highlighting avenues for future translational studies, this illustrates the potential of Deep Visual Multi-omics to dissect cancer heterogeneity and characterize high-risk cell populations.

Humans↗

Qualitative and quantitative analyses of protein phosphorylation in naive and stimulated mouse synaptosomal preparations.

Activity-dependent protein phosphorylation is a highly dynamic yet tightly regulated process essential for cellular signaling. Although recognized as critical for neuronal functions, the extent and stoichiometry of phosphorylation in brain cells remain undetermined. In this study, we resolved activity-dependent changes in phosphorylation stoichiometry at specific sites in distinct subcellular compartments of brain cells. Following highly sensitive phosphopeptide enrichment using immobilized metal affinity chromatography and mass spectrometry, we isolated and identified 974 unique phosphorylation sites on 499 proteins, many of which are novel. To further explore the significance of specific phosphorylation sites, we used isobaric peptide labels and determined the absolute quantity of both phosphorylated and non-phosphorylated peptides of candidate phosphoproteins and estimated phosphorylation stoichiometry. The analyses of phosphorylation dynamics using differentially stimulated synaptic terminal preparations revealed activity-dependent changes in phosphorylation stoichiometry of target proteins. Using this method, we were able to differentiate between distinct isoforms of Ca2+/calmodulin-dependent protein kinase (CaMKII) and identify a novel activity-regulated phosphorylation site on the glutamate receptor subunit GluR1. Together these data illustrate that mass spectrometry-based methods can be used to determine activity-dependent changes in phosphorylation stoichiometry on candidate phosphopeptides following large scale phosphoproteome analysis of brain tissue.

Amino Acid Sequence↗

Database independent detection of isotopically labeled MS/MS spectrum peptide pairs.

Mass spectrometry data generated in differential profiling of complex protein samples are classically exploited using database searches. In addition, quantitative profiling is performed by various methods, one of them using isotopically coded affinity tags, where one typically uses a light and a heavy tag. Here, we present a new algorithm, ICATcher, which detects pairs of light/heavy peptide MS/MS spectra independent of sequence databases. The method can be used for de novo sequencing and detection of posttranslational modifications. ICATcher is distributed as open source software.

Algorithms↗

Proteomic analysis of synaptosomes using isotope-coded affinity tags and mass spectrometry.

Synaptosomes are isolated synapses produced by subcellular fractionation of brain tissue. They contain the complete presynaptic terminal, including mitochondria and synaptic vesicles, and portions of the postsynaptic side, including the postsynaptic membrane and the postsynaptic density (PSyD). A proteomic characterisation of synaptosomes isolated from mouse brain was performed employing the isotope-coded affinity tag (ICAT) method and tandem mass spectrometry (MS/MS). After isotopic labelling and tryptic digestion, peptides were fractionated by cation exchange chromatography and cysteine-containing peptides were isolated by affinity chromatography. The peptides were identified by microcapillary liquid chromatography-electrospray ionisation MS/MS (muLC-ESI MS/MS). In two experiments, peptides representing a total of 1131 database entries were identified. They are involved in different presynaptic and postsynaptic functions, including synaptic vesicle exocytosis for neurotransmitter release, vesicle endocytosis for synaptic vesicle recycling, as well as postsynaptic receptors and proteins constituting the PSyD. Moreover, a large number of soluble and membrane-bound molecules serving functions in synaptic signal transduction and metabolism were detected. The results provide an inventory of the synaptic proteome and confirm the suitability of the ICAT method for the assessment of synaptic structure, function and plasticity.

Animals↗