Endothelial Toll-like receptor 4 is required for microglia activation in the murine retina after systemic lipopolysaccharide exposure.

Background: Clustering of microglia around the vasculature has been reported in the retina and the brain after systemic administration of lipopolysaccharides (LPS) in mice. LPS acts via activation of Toll-like receptor 4 (TRL4), which is expressed in several cell types including microglia, monocytes and vascular endothelial cells. The purpose of this study was to investigate the effect of systemic LPS in the pigmented mouse retina and the involvement of endothelial TLR4 in LPS-induced retinal microglia activation.

Systemic Lipopolysaccharide Exposure Exacerbates Choroidal Neovascularization in Mice.

This study aims to investigate the effect of a systemic lipopolysaccharide (LPS) stimulus in the course of laser-induced choroidal neovascularization (CNV) in C57BL/6 J mice. A group of CNV-subjected mice received 1 mg/kg LPS via the tail vein immediately after CNV induction. Mouse eyes were monitored with fluorescein angiography for 2 weeks.

EVL regulates VEGF receptor-2 internalization and signaling in developmental angiogenesis.

Endothelial tip cells are essential for VEGF-induced angiogenesis, but underlying mechanisms are elusive. The Ena/VASP protein family, consisting of EVL, VASP, and Mena, plays a pivotal role in axon guidance. Given that axonal growth cones and endothelial tip cells share many common features, from the morphological to the molecular level, we investigated the role of Ena/VASP proteins in angiogenesis.

AKAP12 deficiency impairs VEGF-induced endothelial cell migration and sprouting.

Aim: Protein kinase (PK) A anchoring protein (AKAP) 12 is a scaffolding protein that anchors PKA to compartmentalize cyclic AMP signalling. This study assessed the consequences of the downregulation or deletion of AKAP12 on endothelial cell migration and angiogenesis.

Methods: The consequences of siRNA-mediated downregulation AKAP12 were studied in primary cultures of human endothelial cells as well as in endothelial cells and retinas from wild-type versus AKAP12 mice.

SPRED2 deficiency elicits cardiac arrhythmias and premature death via impaired autophagy.

Cardiac functionality is dependent on a balanced protein turnover. Accordingly, regulated protein decay is critical to maintain cardiac function. Here we demonstrate that deficiency of SPRED2, an intracellular repressor of ERK-MAPK signaling markedly expressed in human heart, resulted in impaired autophagy, heart failure, and shortened lifespan.

VASP regulates leukocyte infiltration, polarization, and vascular repair after ischemia.

In ischemic vascular diseases, leukocyte recruitment and polarization are crucial for revascularization and tissue repair. We investigated the role of vasodilator-stimulated phosphoprotein (VASP) in vascular repair. After hindlimb ischemia induction, blood flow recovery, angiogenesis, arteriogenesis, and leukocyte infiltration into ischemic muscles in VASP mice were accelerated.

Phosphorylation of vasodilator-stimulated phosphoprotein contributes to myocardial ischemic preconditioning.

Ischemic preconditioning (IP) is a well-known strategy to protect organs against cell death following ischemia. The previous work has shown that vasodilator-stimulated phosphoprotein (VASP) is involved in cytoskeletal reorganization and that it holds significant importance for the extent of myocardial ischemia reperfusion injury. Yet, the role of VASP during myocardial IP is, to date, not known.

Protein kinase A activation by the anti-cancer drugs ABT-737 and thymoquinone is caspase-3-dependent and correlates with platelet inhibition and apoptosis.

Chemotherapy-induced thrombocytopenia is a common bleeding risk in cancer patients and limits chemotherapy dose and frequency. Recent data from mouse and human platelets revealed that activation of protein kinase A/G (PKA/PKG) not only inhibited thrombin/convulxin-induced platelet activation but also prevented the platelet pro-coagulant state. Here we investigated whether or not PKA/PKG activation could attenuate caspase-dependent apoptosis induced by the anti-cancer drugs ABT-737 (the precursor of navitoclax) and thymoquinone (TQ), thereby potentially limiting chemotherapy-induced thrombocytopenia.

Can erythrocytes release biologically active NO?

Under physiological conditions, endothelial cells and the endothelial nitric oxide (NO) synthase (eNOS) are the main source of NO in the cardiovascular system. However, several other cell types have also been implicated in the NO-dependent regulation of cell function, including erythrocytes. NO derived from red blood cells has been proposed to regulate erythrocyte membrane fluidity, inhibit platelet activation and induce vasodilation in hypoxic areas, but these proposals are highly controversial.

Vasodilator-Stimulated Phosphoprotein (VASP)-dependent and -independent pathways regulate thrombin-induced activation of Rap1b in platelets.

Background: Vasodilator-Stimulated Phosphoprotein (VASP) is involved in the inhibition of agonist-induced platelet aggregation by cyclic nucleotides and the adhesion of platelets to the vascular wall. αIIbβ3 is the main integrin responsible for platelet activation and Rap1b plays a key role in integrin signalling. We investigated whether VASP is involved in the regulation of Rap1b in platelets since VASP-null platelets exhibit augmented adhesion to endothelial cells in vivo.

PKA-regulated VASP phosphorylation promotes extrusion of transformed cells from the epithelium.

At the early stages of carcinogenesis, transformation occurs in single cells within tissues. In an epithelial monolayer, such mutated cells are recognized by their normal neighbors and are often apically extruded. The apical extrusion requires cytoskeletal reorganization and changes in cell shape, but the molecular switches involved in the regulation of these processes are poorly understood.

Mena/VASP and αII-Spectrin complexes regulate cytoplasmic actin networks in cardiomyocytes and protect from conduction abnormalities and dilated cardiomyopathy.

Background: In the heart, cytoplasmic actin networks are thought to have important roles in mechanical support, myofibrillogenesis, and ion channel function. However, subcellular localization of cytoplasmic actin isoforms and proteins involved in the modulation of the cytoplasmic actin networks are elusive. Mena and VASP are important regulators of actin dynamics.

Identification of SPRED2 (sprouty-related protein with EVH1 domain 2) as a negative regulator of the hypothalamic-pituitary-adrenal axis.

Sprouty-related proteins with EVH1 (enabled/vasodilator-stimulated phosphoprotein homology 1) domain (SPREDs) are inhibitors of MAPK signaling. To elucidate SPRED2 in vivo function, we characterized body homeostasis in SPRED2(-/-) mice. They showed a doubled daily water uptake, induced by elevated serum osmolality, originating from increased blood salt load.

Deficiency of vasodilator-stimulated phosphoprotein (VASP) increases blood-brain-barrier damage and edema formation after ischemic stroke in mice.

Background: Stroke-induced brain edema formation is a frequent cause of secondary infarct growth and deterioration of neurological function. The molecular mechanisms underlying edema formation after stroke are largely unknown. Vasodilator-stimulated phosphoprotein (VASP) is an important regulator of actin dynamics and stabilizes endothelial barriers through interaction with cell-cell contacts and focal adhesion sites.

Differential VASP phosphorylation controls remodeling of the actin cytoskeleton.

Proteins of the Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) family link signal transduction pathways to actin cytoskeleton dynamics. VASP is substrate of cAMP-dependent, cGMP-dependent and AMP-activated protein kinases that primarily phosphorylate the sites S157, S239 and T278, respectively. Here, we systematically analyzed functions of VASP phosphorylation patterns for actin assembly and subcellular targeting in vivo and compared the phosphorylation effects of Ena/VASP family members.

TMEM16B, a novel protein with calcium-dependent chloride channel activity, associates with a presynaptic protein complex in photoreceptor terminals.

Photoreceptor ribbon synapses release glutamate in response to graded changes in membrane potential evoked by vast, logarithmically scalable light intensities. Neurotransmitter release is modulated by intracellular calcium levels. Large Ca(2+)-dependent chloride currents are important regulators of synaptic transmission from photoreceptors to second-order neurons; the molecular basis underlying these currents is unclear.

Cytoskeleton assembly at endothelial cell-cell contacts is regulated by alphaII-spectrin-VASP complexes.

Directed cortical actin assembly is the driving force for intercellular adhesion. Regulated by phosphorylation, vasodilator-stimulated phosphoprotein (VASP) participates in actin fiber formation. We screened for endothelial proteins, which bind to VASP, dependent on its phosphorylation status.

Prostaglandin-induced VASP phosphorylation controls alpha II-spectrin breakdown in apoptotic cells.

In pathological conditions, the inflammatory mediator prostaglandin E2 (PGE2) has been shown to induce apoptosis through a cAMP-dependent pathway. However, underlying mechanisms have remained illusive. Irrespective whether apoptosis is induced by the intrinsic or extrinsic pathway, the cysteine protease caspase-3 becomes activated and cleaves many key proteins including spectrins.

AMP-activated protein kinase impairs endothelial actin cytoskeleton assembly by phosphorylating vasodilator-stimulated phosphoprotein.

Vasodilator-stimulated phosphoprotein (VASP) is an actin regulatory protein that links signaling pathways to remodeling of the cytoskeleton. VASP functions are modulated by protein kinases, which phosphorylate the sites Ser-157, Ser-239, and Thr-278. The kinase responsible for Thr-278 phosphorylation, biological functions of the phosphorylation, and association with disease states have remained enigmatic.

Platelets promote coagulation factor XII-mediated proteolytic cascade systems in plasma.

Blood coagulation factor XII (FXII, Hageman factor) is a plasma serine protease which is autoactivated following contact with negatively charged surfaces in a reaction involving plasma kallikrein and high-molecular-weight kininogen (contact phase activation). Active FXII has the ability to initiate blood clotting via the intrinsic pathway of coagulation and inflammatory reactions via the kallikrein-kinin system. Here we have determined FXII-mediated bradykinin formation and clotting in plasma.