Cholesterol is a sterol lipid found in all higher eukaryotic organisms. It is required to consolidate the basic structural integrity and dynamic principles of cellular membranes and participates in many essential cellular processes that range from signal transduction to membrane traffic and metabolism. Moreover, a growing number of clinically highly relevant diseases such as immunological disorders or cancer has been linked to changes or misfunctions in cholesterol homeostasis.
View Article and Find Full Text PDFMechanisms keeping leukocytes distant of local inflammatory processes in a resting state despite systemic release of inflammatory triggers are a pivotal requirement for avoidance of overwhelming inflammation but are ill defined. Dimers of the alarmin S100A8/S100A9 activate Toll-like receptor-4 (TLR4) but extracellular calcium concentrations induce S100A8/S100A9-tetramers preventing TLR4-binding and limiting their inflammatory activity. So far, only antimicrobial functions of released S100A8/S100A9-tetramers (calprotectin) are described.
View Article and Find Full Text PDFAm J Respir Crit Care Med
August 2022
Capillary leakage frequently occurs during sepsis and after major surgery and is associated with microvascular dysfunction and adverse outcome. Procalcitonin is a well-established biomarker in inflammation without known impact on vascular integrity. We determined how procalcitonin induces endothelial hyperpermeability and how targeting procalcitonin protects vascular barrier integrity.
View Article and Find Full Text PDFCholesterol is an essential component of cellular membranes regulating the structural integrity and fluidity of biological bilayers and cellular processes such as signal transduction and membrane trafficking. However, tools to investigate the role and dynamics of cholesterol in live cells are still scarce and often show limited applicability. To address this, we previously developed a class of imidazolium-based cholesterol analogs, CHIMs.
View Article and Find Full Text PDFAnnexin A2 (AnxA2) is a cytosolic Ca regulated membrane binding protein that can induce lipid domain formation and plays a role in exocytosis and endocytosis. To better understand the mode of annexin-membrane interaction, we analyzed membrane-bound AnxA2 assemblies by employing a novel 3-armed chemical crosslinker and specific AnxA2 mutant proteins. Our data show that AnxA2 forms crosslinkable oligomers upon binding to membranes containing negatively charged phospholipids.
View Article and Find Full Text PDFThe specific transport of amphiphilic compounds such as fluorescently labeled phospholipids into cells is a prerequisite for the analysis of highly dynamic cellular processes involving these molecules, e.g., the intracellular distribution and metabolism of phospholipids.
View Article and Find Full Text PDFThe dissipative quartz crystal microbalance technique is a simple and label-free approach to measure simultaneously the mass uptake and viscoelastic properties of the absorbed/immobilized mass on sensor surfaces, allowing the measurements of the interaction of proteins with solid-supported surfaces, such as lipid bilayers, in real-time and with a high sensitivity. Annexins are a highly conserved group of phospholipid-binding proteins that interact reversibly with the negatively charged headgroups via the coordination of calcium ions. Here, we describe a protocol that was employed to quantitatively analyze the binding of annexin A2 (AnxA2) to planar lipid bilayers prepared on the surface of a quartz sensor.
View Article and Find Full Text PDFThe protein-mediated formation of membrane contacts is a crucial event in many cellular processes ranging from the establishment of organelle contacts to the docking of vesicles to a target membrane. Annexins are Ca regulated membrane-binding proteins implicated in providing such membrane contacts; however, the molecular basis of membrane bridging by annexins is not fully understood. We addressed this central question using annexin A2 (AnxA2) that functions in secretory vesicle exocytosis possibly by providing membrane bridges.
View Article and Find Full Text PDFCholesterol is an essential component of most biological membranes and serves important functions in controlling membrane integrity, organization, and signaling. However, probes to follow the dynamic distribution of cholesterol in live cells are scarce and so far show only limited applicability. Herein, we addressed this problem by synthesizing and characterizing a class of versatile and clickable cholesterol-based imidazolium salts.
View Article and Find Full Text PDFJ Photochem Photobiol B
June 2017
Quantum dots (QDs) are fluorescent nanocrystals that present unique optical properties, especially a high photostability. However, their use for intracellular studies is still limited since their passage through the living cell membranes does not occur passively. In this work, we adapted the ethanol injection method to encapsulate cationic hydrophilic QDs into fusogenic liposomes, to deliver them in living cells.
View Article and Find Full Text PDFThe use of Quantum Dots (QDs) as fluorescent probes for understanding biological functions has emerged as an advantageous alternative over application of conventional fluorescent dyes. Intracellular delivery of QDs is currently a specific field of research. When QDs are tracking a specific target in live cells, they are mostly applied for extracellular membrane labeling.
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