Project description:The multitude of obesogenic diets used in rodent studies is enormous and thus hardly manageable. Since standardization is missing and it is presumed that individual compositions provoke individual effects, the choice of quality, quantity and combination of diet ingredients seems to be crucial for the outcome and interpretation of obesity studies. Therefore, the present study was conducted to compare the effects of three commonly used obesogenic diets on selected parameters. Besides basic phenotypic and metabolic characterization, one main aspect was a comparative liver proteome analysis. As expected, the obtained results picture differentiated consequences mainly depending on fat source and/or fat- and sugar quantity. By confirming the general presumption that the choice of nutritional composition is a pivotal factor, the present findings demonstrate that a conscious selection is indispensable for obtaining reliable and sound results in obesity research.In conclusion, we strongly recommend a thorough selection of the appropriate obesogenic diet prior to an experiment and in consideration of the individual research question.
Project description:Keratin cytoskeletal proteins are crucial for the maintenance of skin integrity. Mutations in genes coding for K5 and K14 cause the human skin disorder epidermolysis bullosa simplex (EBS) leading to substantial alterations in keratin assembly and collapse of keratin filaments into cytoplasmic protein aggregates. The phenotypic consequences of K5 and K14 mutations comprise fragility of basal keratinocytes and skin blistering upon mild mechanical trauma. Treatment of EBS is only supportive and consists primarily of wound care and avoidance of mechanical stress. Besides symptomatic care, no efficient therapeutic treatment is available for EBS. In the present study, we used patient-derived keratinocytes carrying the most frequent K14.R125C mutation as a reproducible EBS model to understand EBS pathomechanisms and to develop a therapy approach aimed to restore a functional keratin network. Numerous post-translational modifications (PTMs) such as phosphorylation have been reported to occur on keratins, which affect the organization of keratin networks. Whether keratin mutations affect the occurrence of PTMs and thereby keratin aggregation in EBS is yet unknown. We find that the K14.R125C mutation alters keratin and keratin-associated protein PTMs in distinct ways and suggest that disease mutations and altered PTMs aggravate keratin aggregation. We reason that chemical compounds affecting the interplay of mutations and PTMs enable the reformation of a keratin cytoskeleton from aggregates are potential candidates for combating EBS.
Project description:LYN kinase is a tyrosine kinase, that regulates cellular homeostasis in a context specific manner. Our group could show, that its expression in the leukemic microenvironment of chronic lymphocytic leukemia contributes to disease progression (Nguyen PH et al.; Cancer Cell; 2016). To analyze the effect of LYN kinase on the leukemia supportive phenotype of the bone marrow stromal cell line HS-5, we generated single cell clones of LYN deficient cells. These cells were analyzed in a Multi-Omic approach, including quantitative, label-free proteomic analysis of the Secretome.
Project description:Viruses often induce a complex rewiring of cellular physiology to maximize their propagation. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) expresses high amounts of the viral antagonistic protein Orf9b. Increased amounts and mutated versions of Orf9b were found to correlate with improved transmission of more evolved virus forms such as the Alpha and Omicron variants. Orf9b binds to the mitochondrial surface receptor Tom70 which stiffens its highly flexible structure. Tom70 plays a critical role in the antiviral response since it serves as recruiting factor for the mitochondrial antiviral signaling (MAVS) protein. However, the predominant and MAVS-independent role of Tom70 is that of a receptor component of the mitochondrial import system. Whether Orf9b also interferes with this predominant function of Tom70 is unknown. In this study, we expressed Orf9b in human HEK293 cells and observed the Orf9b-mediated depletion of mitochondrial proteins, particularly in respiring cells. The spectrum of depleted mitochondrial proteins was comparable to that of cells in which Tom70 was depleted, consistent with an Orf9b-mediated impairment of Tom70-dependent protein import. To exclude that the observed depletion was caused by the antiviral response triggered by Orf9b expression, we generated a yeast system in which the yeast Tom70 was replaced by a humanized version of Tom70. Upon expression of Orf9b in these cells, we again observed a general but moderate reduction of mitochondrial proteins. Similar to the situation in human cells, a number of mitochondrial proteins were particular sensitive to Orf9b expression, suggesting a rather specific modulation of the mitochondrial import system. In vitro import experiments with semi-intact cells confirmed this Orf9b-mediated impairment of the mitochondrial protein import. Thus, the SARS-CoV-2 virus seems to modulate the mitochondrial proteome by a direct effect of Orf9b on mitochondrial Tom70-dependent protein import.
Project description:The goal of our study was to characterize glomerulus and particularly podocyte biology during MMF treatment in an immune-triggered proteinuric glomerulopathy. Therefore, nephrotoxic serum nephritis was induced in three-week old wild-type mice. On day 3, half of the mice were treated with MMF (100 mg/kgBW/d p.o.) (NTS+MMF) for one week, the other half of animals with vehicle (NTS+veh). A further group without induction and treatment served as controls (C). On day 10, we performed proteomic analysis of glomeruli.
Project description:Human papillomavirus type 8 (HPV8) is associated with the development of non-melanoma skin cancer. In the past we already delved into the mechanisms involved in keratinocyte invasion, showing that the viral E7 oncoprotein is a key player that drives invasion of basal keratinocytes controlled by the extracellular protein fibronectin. To unravel further downstream effects in E7 expressing keratinocytes we now characterized alterations of the phospho-proteome in E7 expressing N/TERT keratinocytes.