Producing protein nanotubes by sacrificing nanofibres
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Intracellular assembly of supramolecular peptide nanostructures controlled by visible light
The complex dynamics of synthetic supramolecular systems in living cellular environments impede the correlation between the transient hierarchical species and their biological functions. Achieving this correlation demands a breakthrough that combines the precise control of supramolecular events at discrete time points via synthetic chemistry with their real-time visualization in native cells. In the present study, we reported two peptide sequences that undergo visible light-induced molecular and supramolecular transformations to form various assembly species in cells. In contrast to endogenous stimulus-responsive assembly, the proposed photochemistry enables full control over the photolysis reaction where the monomer generation and local concentration regulate the subsequent assembly kinetics. Phasor-fluorescence lifetime imaging traced the formation of various assembly states in cells associated with monomer activation and consumption, whereas correlative light-electron microscopy revealed the intracellular nanofibres formed. The temporally resolved assembly process shows that the emergence of cytotoxicity correlates with the accumulation of oligomers beyond the cellular efflux threshold.
Anionic lipids direct efficient microfluidic encapsulation of stable and functionally active proteins in lipid nanoparticles
Because proteins do not efficiently pass through the plasma membrane, protein therapeutics are limited to target ligands located at the cell surface or in serum. Lipid nanoparticles can facilitate delivery of polar molecules across a membrane. We hypothesized that because most proteins are amphoteric ionizable polycations, proteins would associate with anionic lipids, enabling microfluidic chip assembly of stable EP-LNPs (Encapsulated Proteins in Lipid NanoParticles). Here, by employing anionic lipids we were able to efficiently load proteins into EP-LNPs at protein:lipid w:w ratios of 1:20. Several proteins with diverse molecular weights and isoelectric points were encapsulated at efficiencies of 70 75%–90% and remained packaged for several months. Proteins packaged in EP-LNPs efficiently entered mammalian cells and fungal cells with cell walls. The proteins delivered intracellularly were functional. EP-LNPs technology should improve cellular delivery of medicinal antibodies, enzymes, peptide antimetabolites, and dominant negative proteins, opening new fields of protein therapeutics
Dietary protein restriction elevates FGF21 levels and energy requirements to maintain body weight in lean men
Dietary protein restriction increases energy expenditure and enhances insulin sensitivity in mice. However, the effects of a eucaloric protein-restricted diet in healthy humans remain unexplored. Here, we show in lean, healthy men that a protein-restricted diet meeting the minimum protein requirements for 5 weeks necessitates an increase in energy intake to uphold body weight, regardless of whether proteins are replaced with fats or carbohydrates. Upon reverting to the customary higher protein intake in the following 5 weeks, energy requirements return to baseline levels, thus preventing weight gain. We also show that fasting plasma FGF21 levels increase during protein restriction. Proteomic analysis of human white adipose tissue and in FGF21-knockout mice reveal alterations in key components of the electron transport chain within white adipose tissue mitochondria. Notably, in male mice, these changes appear to be dependent on FGF21. In conclusion, we demonstrate that maintaining body weight during dietary protein restriction in healthy, lean men requires a higher energy intake, partially driven by FGF21-mediated mitochondrial adaptations in adipose tissue.
The comprehensive SARS-CoV-2 ‘hijackome’ knowledge base
The continuous evolution of SARS-CoV-2 has led to the emergence of several variants of concern (VOCs) that significantly affect global health. This study aims to investigate how these VOCs affect host cells at proteome level to better understand the mechanisms of disease. To achieve this, we first analyzed the (phospho)proteome changes of host cells infected with Alpha, Beta, Delta, and Omicron BA.1 and BA.5 variants over time frames extending from 1 to 36 h post infection. Our results revealed distinct temporal patterns of protein expression across the VOCs, with notable differences in the (phospho)proteome dynamics that suggest variant-specific adaptations. Specifically, we observed enhanced expression and activation of key components within crucial cellular pathways such as the RHO GTPase cycle, RNA splicing, and endoplasmic reticulum-associated degradation (ERAD)-related processes. We further utilized proximity biotinylation mass spectrometry (BioID-MS) to investigate how specific mutation of these VOCs influence viral–host protein interactions. Our comprehensive interactomics dataset uncovers distinct interaction profiles for each variant, illustrating how specific mutations can change viral protein functionality. Overall, our extensive analysis provides a detailed proteomic profile of host cells for each variant, offering valuable insights into how specific mutations may influence viral protein functionality and impact therapeutic target identification. These insights are crucial for the potential use and design of new antiviral substances, aiming to enhance the efficacy of treatments against evolving SARS-CoV-2 variants.
Uncovering protein glycosylation dynamics and heterogeneity using deep quantitative glycoprofiling (DQGlyco)
Protein glycosylation regulates essential cellular processes such as signaling, adhesion and cell–cell interactions; however, dysregulated glycosylation is associated with diseases such as cancer. Here we introduce deep quantitative glycoprofiling (DQGlyco), a robust method that integrates high-throughput sample preparation, highly sensitive detection and precise multiplexed quantification to investigate protein glycosylation dynamics at an unprecedented depth. Using DQGlyco, we profiled the mouse brain glycoproteome, identifying 177,198 unique N-glycopeptides—25 times more than previous studies. We quantified glycopeptide changes in human cells treated with a fucosylation inhibitor and characterized surface-exposed glycoforms. Furthermore, we analyzed tissue-specific glycosylation patterns in mice and demonstrated that a defined gut microbiota substantially remodels the mouse brain glycoproteome, shedding light on the link between the gut microbiome and brain protein functions. Additionally, we developed a novel strategy to evaluate glycoform solubility, offering new insights into their biophysical properties. Overall, the in-depth profiling offered by DQGlyco uncovered extensive complexity in glycosylation regulation.
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