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Brown adipose tissue function declines during aging and may contribute to the onset of metabolic disorders such as diabetes and obesity. Only limited understanding of the mechanisms leading to the metabolic impairment of brown adipocytes during aging exists. To this end, interscapular brown adipose tissue samples were collected from young and aged mice for quantification of differential gene expression and metabolite levels. To identify potential processes involved in brown adipocyte dysfunction, metabolite concentrations were correlated to aging and significantly changed candidates were subsequently integrated with a non-targeted proteomic dataset and gene expression analyses. Our results include novel age-dependent correlations of polar intermediates in brown adipose tissue. Identified metabolites clustered around three biochemical processes, specifically energy metabolism, nucleotide metabolism and vitamin metabolism. One mechanism of brown adipose tissue dysfunction may be linked to mast cell activity, and we identify increased histamine levels in aged brown fat as a potential biomarker. In addition, alterations of genes involved in synthesis and degradation of many metabolites were mainly observed in the mature brown adipocyte fraction as opposed to the stromal vascular fraction. These findings may provide novel insights on the molecular mechanisms contributing to the impaired thermogenesis of brown adipocytes during aging.

Phosphatidylinositol 3-kinase type 2α (PI3KC2α) is an essential member of the structurally unresolved class II PI3K family with crucial functions in lipid signaling, endocytosis, angiogenesis, viral replication, platelet formation and a role in mitosis. The molecular basis of these activities of PI3KC2α is poorly understood. Here, we report high-resolution crystal structures as well as a 4.4-Å cryogenic-electron microscopic (cryo-EM) structure of PI3KC2α in active and inactive conformations. We unravel a coincident mechanism of lipid-induced activation of PI3KC2α at membranes that involves large-scale repositioning of its Ras-binding and lipid-binding distal Phox-homology and C-C2 domains, and can serve as a model for the entire class II PI3K family. Moreover, we describe a PI3KC2α-specific helical bundle domain that underlies its scaffolding function at the mitotic spindle. Our results advance our understanding of PI3K biology and pave the way for the development of specific inhibitors of class II PI3K function with wide applications in biomedicine. High-resolution structures of phosphatidylinositol 3-kinase (PI3K) type IIa unravel a coincident mechanism of lipid-induced enzyme activation and enable the development of inhibitors of class II PI3K function with applications in biomedicine.

3-Chloro-1,2-propanediol (3-MCPD) and 2-chloro-1,3-propanediol (2-MCPD) are heat-induced food contaminants being present either as free substances or as fatty acid esters in numerous foods. 3-MCPD was classified to be possibly carcinogenic to humans (category 2B) with kidney and testis being the primary target organs according to animal studies. A previous 28-day oral feeding study with rats revealed that the endogenous antioxidant protein DJ-1 was strongly deregulated at the protein level in kidney, liver, and testis of the experimental animals that had been treated either with 3-MCPD, 2-MCPD or their dipalmitate esters. Here we show that this deregulation is due to the oxidation of a conserved, redox-active cysteine residue (Cys106) of DJ-1 to a cysteine sulfonic acid which is equivalent to loss of function of DJ-1. Irreversible oxidation of DJ-1 is associated with a number of oxidative stress-related diseases such as Parkinson, cancer, and type II diabetes. It is assumed that 3-MCPD or 2-MCPD do not directly oxidize DJ-1, but that these substances induce the formation of reactive oxygen species (ROS) which in turn trigger DJ-1 oxidation. The implications of 3-MCPD/2-MCPD-mediated ROS formation in vivo for the ongoing risk assessment of these compounds as well as the potential of oxidized DJ-1 to serve as a novel effect biomarker for 3-MCPD/2-MCPD toxicity are being discussed.

Equine herpesvirus type 1 (EHV-1) causes encephalomyelopathy and abortion, for which cell-associated viremia and subsequent virus transfer to and replication in endothelial cells (EC) are responsible and prerequisites. Viral and cellular molecules responsible for efficient cell-to-cell spread of EHV-1 between peripheral blood mononuclear cells (PBMC) and EC remain unclear. We have generated EHV-1 mutants lacking ORF1, ORF2, and ORF17 genes, either individually or in combination. Mutant viruses were analyzed for their replication properties in cultured equine dermal cells, PBMC infection efficiency, virus-induced changes in the PBMC proteome, and cytokine and chemokine expression profiles. ORF1, ORF2, and ORF17 are not essential for virus replication, but ORF17 deletion resulted in a significant reduction in plaque size. Deletion of ORF2 and ORF17 gene significantly reduced cell-to-cell virus transfer from virus-infected PBMC to EC. EHV-1 infection of PBMC resulted in upregulation of several pathways such as Ras signaling, oxidative phosphorylation, platelet activation and leukocyte transendothelial migration. In contrast, chemokine signaling, RNA degradation and apoptotic pathways were downregulated. Deletion of ORF1, ORF2 and ORF17 modulated chemokine signaling and MAPK pathways in infected PBMC, which may explain the impairment of virus spread between PBMC and EC. The proteomic results were further confirmed by chemokine assays, which showed that virus infection dramatically reduced the cytokine/chemokine release in infected PBMC. This study uncovers cellular proteins and pathways influenced by EHV-1 after PBMC infection and provide an important resource for EHV-1 pathogenesis. EHV-1-immunomodulatory genes could be potential targets for the development of live attenuated vaccines or therapeutics against virus infection.

Microorganisms form surface-attached communities, termed biofilms, which can serve as protection against host immune reactions or antibiotics. Bacillus subtilis biofilms contain TasA as major proteinaceous component in addition to exopolysaccharides. In stark contrast to the initially unfolded biofilm proteins of other bacteria, TasA is a soluble, stably folded monomer, whose structure we have determined by X-ray crystallography. Subsequently, we characterized in vitro different oligomeric forms of TasA by NMR, EM, X-ray diffraction, and analytical ultracentrifugation (AUC) experiments. However, by magic-angle spinning (MAS) NMR on live biofilms, a swift structural change toward only one of these forms, consisting of homogeneous and protease-resistant, β-sheet–rich fibrils, was observed in vivo. Thereby, we characterize a structural change from a globular state to a fibrillar form in a functional prokaryotic system on the molecular level.

Microorganisms form surface-attached communities, termed biofilms, which can serve as protection against host immune reactions or antibiotics. Bacillus subtilis biofilms contain TasA as major proteinaceous component in addition to exopolysaccharides. In stark contrast to the initially unfolded biofilm proteins of other bacteria, TasA is a soluble, stably folded monomer, whose structure we have determined by X-ray crystallography. Subsequently, we characterized in vitro different oligomeric forms of TasA by NMR, EM, X-ray diffraction, and analytical ultracentrifugation (AUC) experiments. However, by magic-angle spinning (MAS) NMR on live biofilms, a swift structural change toward only one of these forms, consisting of homogeneous and protease-resistant, β-sheet–rich fibrils, was observed in vivo. Thereby, we characterize a structural change from a globular state to a fibrillar form in a functional prokaryotic system on the molecular level.

Element concentrations in tree rings can be used to monitor changes in environmental quality. With regard to the detection of incipient soil acidification, the manganese concentration in soils and plants is a significant marker for the switch of acid buffering in soils mainly with the exchange of base cations or with the dissolution of aluminium oxides. This is a site-specific non-linear event, indicating the onset of Al³⁺ dominance in the soil solution, were damages to vegetation due to acid stress become possible. This turning point is also a marker for the attainment of pH 4.2 in soils, the critical threshold used for critical load calculations. On a plot of the German environmental monitoring in forests the element concentrations in tree rings of 60-year-old spruces reveal a distinct decline in the Mn concentration, beginning in the late 1960s ending in the late 1970s. With this information it was possible to assume a base saturation in the soil of about 15-20% in the late 1960s, and to model the development of the base saturation of the site. A decline from 17.5 to 6% within one decade could be related to the deposition. This is in accordance with the base saturation of 6.5%, measured in 1993 for this site, but also for adjacent spruce sites on the same geological substrate. The knowledge of the time span were this site-specific non-linear event occurred is essential for the reconstruction of the soil chemistry of a site. Moreover, it enables the assignment of observations like 'forest damages' to the onset of changes in environmental quality.

Intrinsically disordered proteins (IDPs) play a vital role in biological processes that rely on transient molecular compartmentation1. In T cells, the dynamic switching between migration and adhesion mandates a high degree of plasticity in the interplay of adhesion and signaling molecules with the actin cytoskeleton2,3. Here, we show that the N-terminal intrinsically disordered region (IDR) of adhesion- and degranulation-promoting adapter protein (ADAP) acts as a multipronged scaffold for G- and F-actin, thereby promoting actin polymerization and bundling. Positively charged motifs, along a sequence of at least 200 amino acids, interact with both longitudinal sides of G-actin in a promiscuous manner. These polymorphic interactions with ADAP become constrained to one side once F-actin is formed. Actin polymerization by ADAP acts in synergy with a capping protein but competes with cofilin. In T cells, ablation of ADAP impairs adhesion and migration with a time-dependent reduction of the F-actin content in response to chemokine or T cell receptor (TCR) engagement. Our data suggest that IDR-assisted molecular crowding of actin above the critical concentration defines a new mechanism to regulate cytoskeletal dynamics. The principle of IDRs serving as molecular sponges to facilitate regulated self-assembly of filament-forming proteins might be a general phenomenon.

The number of publications in the field of chemical cross-linking combined with mass spectrometry (XL-MS) to derive constraints for protein three-dimensional structure modeling and to probe protein-protein interactions has largely increased during the last years. As the technique is now becoming routine for in vitro and in vivo applications in proteomics and structural biology there is a pressing need to define protocols as well as data analysis and reporting formats that are generally accepted in the field and that have shown to lead to high-quality results. This first, community-based harmonization study on XL-MS is based on the results of 32 groups participating worldwide. The aim of this paper is to summarize the status quo of XL-MS and to compare and evaluate existing cross-linking strategies. From the results obtained, common protocols will be established. Our study serves as basis for establishing best practice guidelines in the field for conducting cross-linking experiments, performing data analysis, and reporting formats with the ultimate goal of assisting scientists to generate accurate and reproducible XL-MS results.