P-selectin-dependent leukocyte adhesion is governed by endolysosomal two-pore channel 2.

Upon proinflammatory challenges, endothelial cell surface presentation of the leukocyte receptor P-selectin, together with the stabilizing co-factor CD63, is needed for leukocyte capture and is mediated via demand-driven exocytosis from the Weibel-Palade bodies that fuse with the plasma membrane. We report that neutrophil recruitment to activated endothelium is significantly reduced in mice deficient for the endolysosomal cation channel TPC2 and in human primary endothelial cells with pharmacological TPC2 block. We observe less CD63 signal in whole-mount stainings of proinflammatory-activated cremaster muscles from TPC2 knockout mice.

Biodegradable and Dual-Responsive Polypeptide-Shelled Cyclodextrin-Containers for Intracellular Delivery of Membrane-Impermeable Cargo.

The transport of membrane impermeable compounds into cells is a prerequisite for the efficient cellular delivery of hydrophilic and amphiphilic compounds and drugs. Transport into the cell's cytosolic compartment should ideally be controllable and it should involve biologically compatible and degradable vehicles. Addressing these challenges, nanocontainers based on cyclodextrin amphiphiles that are stabilized by a biodegradable peptide shell are developed and their potential to deliver fluorescently labeled cargo into human cells is analyzed.

TSC1 binding to lysosomal PIPs is required for TSC complex translocation and mTORC1 regulation.

The TSC complex is a critical negative regulator of the small GTPase Rheb and mTORC1 in cellular stress signaling. The TSC2 subunit contains a catalytic GTPase activating protein domain and interacts with multiple regulators, while the precise function of TSC1 is unknown. Here we provide a structural characterization of TSC1 and define three domains: a C-terminal coiled-coil that interacts with TSC2, a central helical domain that mediates TSC1 oligomerization, and an N-terminal HEAT repeat domain that interacts with membrane phosphatidylinositol phosphates (PIPs).

An Imidazolium-Based Lipid Analogue as a Gene Transfer Agent.

A dicationic imidazolium salt is described and investigated towards its application for gene transfer. The polar head group and the long alkyl chains in the backbone contribute to a lipid-like behavior, while an alkyl ammonium group provides the ability for crucial electrostatic interaction for the transfection process. Detailed biophysical studies regarding its impact on biological membrane models and the propensity of vesicle fusion are presented.

Membrane Binding Promotes Annexin A2 Oligomerization.

Annexin 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.

Controlled Cellular Delivery of Amphiphilic Cargo by Redox-Responsive Nanocontainers.

The 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.

Phosphorescent cationic iridium(iii) complexes dynamically bound to cyclodextrin vesicles: applications in live cell imaging.

We report cationic Ir(iii) complexes functionalized with adamantyl groups designed to bind to β-cyclodextrin vesicles (CDV) with high affinity ( = 1 × 10 M). The emission of the complexes is tuned by changing the nature of the cyclometalating ligands. The host-guest adduct of CDV and Ir(iii) complexes shows increased and significantly blue-shifted emission due to the lower mobility of the Ir(iii)-complexes residing in the less polar environment of the vesicle surface.