Targeting Platelet GPVI Plus rt-PA Administration but Not α2β1-Mediated Collagen Binding Protects against Ischemic Brain Damage in Mice.

Platelet collagen interactions at sites of vascular injuries predominantly involve glycoprotein VI (GPVI) and the integrin α2β1. Both proteins are primarily expressed on platelets and megakaryocytes whereas GPVI expression is also shown on endothelial and integrin α2β1 expression on epithelial cells. We recently showed that depletion of GPVI improves stroke outcome without increasing the risk of cerebral hemorrhage.

Description of a Novel Phosphodiesterase (PDE)-3 Inhibitor Protecting Mice From Ischemic Stroke Independent From Platelet Function.

Background and Purpose- Acetylsalicylic acid and clopidogrel are the 2 main antithrombotic drugs for secondary prevention in patients with ischemic stroke (IS) without indication for anticoagulation. Because of their limited efficacy and potential side effects, novel antiplatelet agents are urgently needed. Cilostazol, a specific phosphodiesterase (PDE)-3 inhibitor, protected from IS in clinical studies comprising mainly Asian populations.

How is the formation of microthrombi after traumatic brain injury linked to inflammation?

Traumatic brain injury (TBI) is characterized by mechanical disruption of brain tissue due to an external force and by subsequent secondary injury. Secondary brain injury events include inflammatory responses and the activation of coagulation resulting in microthrombi formation in the brain vasculature. Recent research suggests that these mechanisms do not work independently.

Influence of Thrombolysis on the Safety and Efficacy of Blocking Platelet Adhesion or Secretory Activity in Acute Ischemic Stroke in Mice.

In acute ischemic stroke (AIS), there is an alarming discrepancy between recanalization rates of up to 70% by combined recombinant tissue-type plasminogen activator (rt-PA) therapy and mechanical thrombectomy, and no clinical benefit in at least every second stroke patient. This is partly due to ischemia/reperfusion (I/R) injury. In a translational approach, we used mice lacking dense- (Unc13d) or α-granules (Nbeal2) and mice after blocking of platelet glycoprotein receptor (GP) Ib conferring protection from I/R injury.

Flotillin scaffold activity contributes to type VII secretion system assembly in Staphylococcus aureus.

Scaffold proteins are ubiquitous chaperones that promote efficient interactions between partners of multi-enzymatic protein complexes; although they are well studied in eukaryotes, their role in prokaryotic systems is poorly understood. Bacterial membranes have functional membrane microdomains (FMM), a structure homologous to eukaryotic lipid rafts. Similar to their eukaryotic counterparts, bacterial FMM harbor a scaffold protein termed flotillin that is thought to promote interactions between proteins spatially confined to the FMM.

Blocking of platelet glycoprotein receptor Ib reduces "thrombo-inflammation" in mice with acute ischemic stroke.

Background: Ischemic stroke causes a strong inflammatory response that includes T cells, monocytes/macrophages, and neutrophils. Interaction of these immune cells with platelets and endothelial cells facilitates microvascular dysfunction and leads to secondary infarct growth. We recently showed that blocking of platelet glycoprotein (GP) receptor Ib improves stroke outcome without increasing the risk of intracerebral hemorrhage.

Inhibition of Platelet GPVI Protects Against Myocardial Ischemia-Reperfusion Injury.

Objective: The objective of this study was to investigate the effects of platelet inhibition on myocardial ischemia-reperfusion (IR) injury.

Approach And Results: Timely restoration of coronary blood flow after myocardial infarction is indispensable but leads to additional damage to the heart (myocardial IR injury). Microvascular dysfunction contributes to myocardial IR injury.

OmpW of Caulobacter crescentus Functions as an Outer Membrane Channel for Cations.

Caulobacter crescentus is an oligotrophic bacterium that lives in dilute organic environments such as soil and freshwater. This bacterium represents an interesting model for cellular differentiation and regulation because daughter cells after division have different forms: one is motile while the other is non-motile and can adhere to surfaces. Interestingly, the known genome of C.

Eya4 Induces Hypertrophy via Regulation of p27kip1.

Background: E193, a heterozygous truncating mutation in the human transcription cofactor Eyes absent 4 (Eya4), causes hearing impairment followed by dilative cardiomyopathy.

Methods And Results: In this study, we first show Eya4 and E193 alter the expression of p27(kip1) in vitro, suggesting Eya4 is a negative regulator of p27. Next, we generated transgenic mice with cardiac-specific overexpression of Eya4 or E193.

Cooperative and alternate functions for STIM1 and STIM2 in macrophage activation and in the context of inflammation.

Calcium (Ca(2+)) signaling in immune cells, including macrophages, controls a wide range of effector functions that are critical for host defense and contribute to inflammation and autoimmune diseases. However, receptor-mediated Ca(2+) responses consist of complex mechanisms that make it difficult to identify the pathogenesis and develop therapy. Previous studies have revealed the importance of the Ca(2+) sensor STIM1 and store-operated Ca(2+)-entry (SOCE) for Fcγ-receptor activation and IgG-induced inflammation.

Loss of the Coffin-Lowry syndrome-associated gene RSK2 alters ERK activity, synaptic function and axonal transport in Drosophila motoneurons.

Plastic changes in synaptic properties are considered as fundamental for adaptive behaviors. Extracellular-signal-regulated kinase (ERK)-mediated signaling has been implicated in regulation of synaptic plasticity. Ribosomal S6 kinase 2 (RSK2) acts as a regulator and downstream effector of ERK.

The Expression of Tubb2b Undergoes a Developmental Transition in Murine Cortical Neurons.

The development of the mammalian brain requires the generation, migration, and differentiation of neurons, cellular processes that are dependent on a dynamic microtubule cytoskeleton. Mutations in tubulin genes, which encode for the structural subunits of microtubules, cause detrimental neurological disorders known as the tubulinopathies. The disease spectra associated with different tubulin genes are overlapping but distinct, an observation believed to reflect functional specification of this multigene family.

The Autoimmunity-Associated Gene CLEC16A Modulates Thymic Epithelial Cell Autophagy and Alters T Cell Selection.

CLEC16A variation has been associated with multiple immune-mediated diseases, including type 1 diabetes, multiple sclerosis, systemic lupus erythematosus, celiac disease, Crohn's disease, Addison's disease, primary biliary cirrhosis, rheumatoid arthritis, juvenile idiopathic arthritis, and alopecia areata. Despite strong genetic evidence implicating CLEC16A in autoimmunity, this gene's broad association with disease remains unexplained. We generated Clec16a knock-down (KD) mice in the nonobese diabetic (NOD) model for type 1 diabetes and found that Clec16a silencing protected against autoimmunity.

Orai1 controls C5a-induced neutrophil recruitment in inflammation.

Stromal interaction molecule 1 (STIM1)-dependent store operated calcium-entry (SOCE) through Orai1-mediated calcium (Ca(2+) ) influx is considered a major pathway of Ca(2+) signaling, serving T-cell, mast cell, and platelet responses. Here, we show that Orai1 is critical for neutrophil function. Orai1-deficient neutrophils present defects in fMLP and complement C5a-induced Ca(2+) influx and migration, although they respond normally to another chemoattractant, CXCL2.

Platelets are relevant mediators of renal injury induced by primary endothelial lesions.

Several studies have suggested a prominent (pro)inflammatory and harmful role of platelets in renal disease, and newer work has also demonstrated platelet release of proangiogenic factors. In the present study, we investigated the role of platelets in a mouse model of selective endothelial cell injury using either platelet depletion or the pharmacological P2Y12 receptor blocker clopidogrel as an interventional strategy. The concanavalin A/anti-concanavalin A model was induced in left kidneys of C57bl/6J wild-type mice after initial platelet depletion or platelet-inhibiting therapy using clopidogrel.

Novel receptor-derived cyclopeptides to treat heart failure caused by anti-β1-adrenoceptor antibodies in a human-analogous rat model.

Despite recent therapeutic advances the prognosis of heart failure remains poor. Recent research suggests that heart failure is a heterogeneous syndrome and that many patients have stimulating auto-antibodies directed against the second extracellular loop of the β1 adrenergic receptor (β1EC2). In a human-analogous rat model such antibodies cause myocyte damage and heart failure.

High-resolution spatiotemporal analysis of receptor dynamics by single-molecule fluorescence microscopy.

Single-molecule microscopy is emerging as a powerful approach to analyze the behavior of signaling molecules, in particular concerning those aspect (e.g., kinetics, coexistence of different states and populations, transient interactions), which are typically hidden in ensemble measurements, such as those obtained with standard biochemical or microscopy methods.

Real-time monitoring of GPCR/cAMP signalling by FRET and single-molecule microscopy.

G-protein-coupled receptors (GPCRs), located on the surface of virtually every cell in our organism, mediate the effects of many hormones and neurotransmitters. Although GPCRs have been extensively studied for more than 4 decades using pharmacological and biochemical methods, the recent introduction of optical methods such as fluorescence resonance energy transfer (FRET) and single-molecule microscopy is fostering novel and important discoveries in the field. Here, we review the use of such optical methods, focusing on some recent examples of their application to important and still unresolved questions concerning the spatial organisation and dynamics of GPCR signalling.

CXCR4 blockade induces atherosclerosis by affecting neutrophil function.

Aims: The SDF-1α/CXCR4 dyad was previously shown by us and others to be instrumental in intimal hyperplasia as well as early stage atherosclerosis. We here sought to investigate its impact on clinically relevant stages of atherosclerosis in mouse and man.

Methods And Results: Immunohistochemical analysis of CXCR4 expression in human atherosclerotic lesions revealed a progressive accumulation of CXCR4(+) cells during plaque progression.

Kinetics and mechanism of G protein-coupled receptor activation.

The activation of a G protein-coupled receptor is generally triggered by binding of an agonist to the receptor's binding pocket, or, in the case of rhodopsin, by light-induced changes of the pre-bound retinal. This is followed by a series of a conformational changes towards an active receptor conformation, which is capable of signalling to G proteins and other downstream proteins. In the past few years, a number of new techniques have been employed to analyze the kinetics of this activation process, including X-ray crystallographic three-dimensional structures of receptors in the inactive and the active states, NMR studies of labelled receptors, molecular simulations, and optical analyses with fluorescence resonance energy transfer (FRET).

Cryo-electron microscopic structure of SecA protein bound to the 70S ribosome.

SecA is an ATP-dependent molecular motor pumping secretory and outer membrane proteins across the cytoplasmic membrane in bacteria. SecA associates with the protein-conducting channel, the heterotrimeric SecYEG complex, in a so-called posttranslational manner. A recent study further showed binding of a monomeric state of SecA to the ribosome.

Inhibitions of the translocation pore of Clostridium botulinum C2 toxin by tailored azolopyridinium salts protects human cells from intoxication.

C2 toxin from Clostridium botulinum represents the prototype of clostridial binary actin ADP-ribosylating toxins which destroy the actin-cytoskeleton of mammalian cells and cause severe enteric diseases in humans and animals. After receptor-mediated endocytosis of the C2 toxin complex, the binding/translocation component C2IIa forms a heptameric transmembrane pore in membranes of acidified endosomal vesicles. The separate ADP-ribosyltransferase component C2I translocates through this C2IIa-pore from the endosomal lumen into the cytosol.