Project description:Cellular functional pathways have evolved through selection based on fitness benefits conferred through protein intra- and inter-molecular interactions that comprise all protein conformational features and protein-protein interactions, collectively referred to as the interactome. While the interactome is regulated by proteome levels, it is also regulated independently by, post translational modification, co-factor, and ligand levels, as well as local protein environmental factors, such as osmolyte concentration, pH, ionic strength, temperature and others. In modern biomedical research, cultivatable cell lines have become an indispensable tool, with selection of optimal cell lines that exhibit specific functional profiles being critical for success in many cases. While it is clear that cell lines derived from different cell types have differential proteome levels, increased understanding of large-scale functional differences requires additional information beyond abundance level measurements, including how protein conformations and interactions are altered in certain cell types to shape functional landscapes. Here, we employed quantitative in vivo protein cross-linking coupled to mass spectrometry to probe large-scale protein conformational and interaction changes among three commonly employed human cell lines, HEK293, MCF-7, and HeLa cells. Isobaric quantitative Protein Interaction Reporter (iqPIR) technologies were used to obtain quantitative values of cross-linked peptides across three cell lines. These data illustrated highly reproducible (R2 values larger than 0.8 for all biological replicates) quantitative interactome levels across multiple biological replicates. We also measured protein abundance levels in these cells using data independent acquisition quantitative proteomics methods. Combining quantitative interactome and proteomics information allowed visualization of cell type-specific interactome changes mediated by proteome level adaptations as well as independently regulated interactome changes to gain deeper insight into possible drivers of these changes. Among the biggest detected alterations in protein interactions and conformations are changes in cytoskeletal proteins, RNA-binding proteins, chromatin remodeling complexes, mitochondrial proteins, and others. Overall, these data demonstrate the utility and reproducibility of quantitative cross-linking to study systems-level interactome variations. Moreover, these results illustrate how combined quantitative interactomics and proteomics can provide unique insight on cellular functional landscapes.

Project description:Evolution of multicellular life forms has involved adaptation of organs that consist of multiple cell types, each with unique functional properties that as a collection, achieve complex organ function. Since each cell type is adapted to deliver specific functionality within the context of an organ, knowledge on functional landscapes occupied by individual cell types could improve comprehension of organ function at the molecular level. In kidney, podocytes and tubules are two cell types that work together, each with vastly different functional roles. Podocytes envelop the blood vessels in the glomerulus and act as filters while tubules, located downstream of the glomerulus, are responsible for reabsorption of important nutrients. Mitochondria hold a critical and well-studied role in tubules due to the high energetic requirements required to fulfill their function. In podocytes however, questions remain regarding the relevance of mitochondrial function in both normal physiology and pathology . Quantitative cross-linking mass spectrometry and proteomics together with a transgenic mitochondrial tagging strategy were used to investigate kidney cell-type specificity of mitochondria. These efforts revealed that despite similarities of podocyte and tubule mitochondrial proteomes, each contain unique features corresponding to known distinct functional roles. These include increased demand for energy production through the TCA cycle in tubules and increased detoxification demand in podocytes. Moreover, tubule and podocyte mitochondrial interactome differences revealed additional cell-type specific functional insights with alterations in betaine metabolism, lysine degradation, and other pathways not regulated through proteome abundance levels. Most importantly, these efforts illustrate that cell specific mitochondrial interactome differences within an organ can now be visualized. Therefore, this approach can generally be used to map cell-specific mitochondrial changes in disease, aging or even with therapy to better understand the roles and contributions of each cell type in normal physiology and pathology within an organ in ways not previously possible .

			Action	DRS
	2024-06-18-decoys-contam-20240606_human_uniprot_isoforms_3xflag.fasta	Fasta
	20240703_EX1_UM7_linke004_SA_EXT00_VL007-TOMM22-FLAG-I-lowpH.raw	Raw
	20240703_EX1_UM7_linke004_SA_EXT00_VL007-ev-I-lowpH.raw	Raw
	20240703_EX1_UM7_linke004_SA_EXT00_VL008-22-XL.raw	Raw
	20240703_EX1_UM7_linke004_SA_EXT00_VL008-22.raw	Raw

Dataset Information

A large-scale map of transient and constitutive interactors of human TOM complex enabled by crosslinking

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