Sugar uptake, metabolism, and chloride secretion in the rectal gland of the spiny dogfish .

The rectal gland of the spiny dogfish secretes a salt solution isosmotic with plasma that maintains the salt homeostasis of the fish. It secretes salt against an electrochemical gradient that requires the expenditure of energy. Isolated rectal glands perfused without glucose secrete salt, albeit at a rate about 30% of glands perfused with 5 mM glucose.

Identification of extant vertebrate VWF: evolutionary conservation of primary hemostasis.

Hemostasis in vertebrates involves both a cellular and a protein component. Previous studies in jawless vertebrates (cyclostomes) suggest that the protein response, which involves thrombin-catalyzed conversion of a soluble plasma protein, fibrinogen, into a polymeric fibrin clot, is conserved in all vertebrates. However, similar data are lacking for the cellular response, which in gnathostomes is regulated by von Willebrand factor (VWF), a glycoprotein that mediates the adhesion of platelets to the subendothelial matrix of injured blood vessels.

A role of stochastic phenotype switching in generating mosaic endothelial cell heterogeneity.

Previous studies have shown that biological noise may drive dynamic phenotypic mosaicism in isogenic unicellular organisms. However, there is no evidence for a similar mechanism operating in metazoans. Here we show that the endothelial-restricted gene, von Willebrand factor (VWF), is expressed in a mosaic pattern in the capillaries of many vascular beds and in the aorta.

PGC-1α induces SPP1 to activate macrophages and orchestrate functional angiogenesis in skeletal muscle.

Rationale: Mechanisms of angiogenesis in skeletal muscle remain poorly understood. Efforts to induce physiological angiogenesis hold promise for the treatment of diabetic microvascular disease and peripheral artery disease but are hindered by the complexity of physiological angiogenesis and by the poor angiogenic response of aged and patients with diabetes mellitus. To date, the best therapy for diabetic vascular disease remains exercise, often a challenging option for patients with leg pain.

FOXO1-mediated activation of Akt plays a critical role in vascular homeostasis.

Rationale: Forkhead box-O transcription factors (FoxOs) transduce a wide range of extracellular signals, resulting in changes in cell survival, cell cycle progression, and several cell type-specific responses. FoxO1 is expressed in many cell types, including endothelial cells (ECs). Previous studies have shown that Foxo1 knockout in mice results in embryonic lethality at E11 because of impaired vascular development.

Critical role of sphingosine-1-phosphate receptor 2 (S1PR2) in acute vascular inflammation.

The endothelium, as the interface between blood and all tissues, plays a critical role in inflammation. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid, highly abundant in plasma, that potently regulates endothelial responses through interaction with its receptors (S1PRs). Here, we studied the role of S1PR2 in the regulation of the proadhesion and proinflammatory phenotype of the endothelium.

The flow dependency of Tie2 expression in endotoxemia.

Rationale: Tie2 is predominantly expressed by endothelial cells and is involved in vascular integrity control during sepsis. Changes in Tie2 expression during sepsis development may contribute to microvascular dysfunction. Understanding the kinetics and molecular basis of these changes may assist in the development of therapeutic intervention to counteract microvascular dysfunction.

Role of RNA splicing in mediating lineage-specific expression of the von Willebrand factor gene in the endothelium.

We previously demonstrated that the first intron of the human von Willebrand factor (vWF) is required for gene expression in the endothelium of transgenic mice. Based on this finding, we hypothesized that RNA splicing plays a role in mediating vWF expression in the vasculature. To address this question, we used transient transfection assays in human endothelial cells and megakaryocytes with intron-containing and intronless human vWF promoter-luciferase constructs.

Erg is a crucial regulator of endocardial-mesenchymal transformation during cardiac valve morphogenesis.

During murine embryogenesis, the Ets factor Erg is highly expressed in endothelial cells of the developing vasculature and in articular chondrocytes of developing bone. We identified seven isoforms for the mouse Erg gene. Four share a common translational start site encoded by exon 3 (Ex3) and are enriched in chondrocytes.

RhoJ is an endothelial cell-restricted Rho GTPase that mediates vascular morphogenesis and is regulated by the transcription factor ERG.

ERG is a member of the ETS transcription factor family that is highly enriched in endothelial cells (ECs). To further define the role of ERG in regulating EC function, we evaluated the effect of ERG knock-down on EC lumen formation in 3D collagen matrices. Blockade of ERG using siRNA completely interferes with EC lumen formation.

Vascular bed-specific regulation of the von Willebrand factor promoter in the heart and skeletal muscle.

A region of the human von Willebrand factor (VWF) gene between -2812 and the end of the first intron (termed vWF2) was previously shown to direct expression in the endothelium of capillaries and a subset of larger blood vessels in the heart and skeletal muscle. Here, our goal was to delineate the DNA sequences responsible for this effect. A series of constructs containing deletions or mutations of vWF2 coupled to LacZ were targeted to the Hprt locus of mice, and the resulting animals were analyzed for reporter gene expression.

Intracellular Ca2+ can compensate for the lack of NADPH oxidase-derived ROS in endothelial cells.

The aim of the present study is to determine the role of intracellular Ca(2+) in VEGF signaling. We demonstrate that reduction in Ca(2+) by chelating compound BAPTA-AM or by IP(3)-endoplasmic reticulum blocker 2-APB selectively inhibited VEGF-induced activation of c-Src-PI3K-Akt but not ERK1/2 in human coronary artery endothelial cells (HCAEC). We also show that the selective inhibitory effects of NADPH oxidase knockdown on VEGF-mediated activation of c-Src-PI3K-Akt signaling and cell proliferation in HCAEC can be reversed by increase in intracellular Ca(2+).

Differential roles for ETS, CREB, and EGR binding sites in mediating VEGF receptor 1 expression in vivo.

Vascular endothelial growth factor receptor 1 (VEGFR1) is a marker for endothelial-specific gene expression. We previously reported that the human VEGFR1 promoter (between -748 and +284) contains information for expression in the intact endothelium of transgenic mice. The objective of this study was to dissect the cis-regulatory elements underlying VEGFR1 promoter activity in vitro and in vivo.

Hepatocyte growth factor inhibits VEGF-forkhead-dependent gene expression in endothelial cells.

Objective: Recently, we reported that the forkhead transcription factor, FKHR/FOXO1, is required for vascular endothelial growth factor (VEGF)-mediated upregulation of a number of genes in endothelial cells. Here, we tested the hypothesis that hepatocyte growth factor (HGF), a potent activator of PI3K-Akt in endothelial cells, is capable of depleting the nucleus of FKHR/FOXO1 and thus inhibiting VEGF induction of this class of genes.

Methods And Results: Incubation of human coronary artery endothelial cells with HGF induced prolonged PI3K/Akt-dependent phosphorylation and nuclear exclusion of FKHR/FOXO1.

A prospective, observational study of soluble FLT-1 and vascular endothelial growth factor in sepsis.

Prior murine and human studies suggest that vascular endothelial growth factor (VEGF) contributes to endothelial cell activation and severity of illness in sepsis. Furthermore, circulating levels of soluble VEGF receptor 1 (sFLT) levels were found to increase as part of the early response to sepsis in mice. The objective of the study was to evaluate the blood levels of free VEGF-A and sFLT in patients presenting to the emergency department (ED) with suspected infection and to assess the relationship of these levels with severity of illness and inflammation.

Thrombin downregulates thrombomodulin expression and activity in primary human endothelial cells.

Thrombomodulin (TM) is a cell surface anticoagulant glycoprotein that plays a key role in the protein C pathway. TM expression in endothelial cells may be modulated by a variety of extracellular signals. Most notably, TM has been shown to be downregulated by inflammatory mediators, such as tumor necrosis factor-alpha and lipopolysaccharide.

A GABP-binding element in the Robo4 promoter is necessary for endothelial expression in vivo.

We recently demonstrated that the 3-kb 5'-flanking region of the human ROBO4 gene directs endothelial cell-specific expression in vitro and in vivo. Moreover, a GA-binding protein (GABP)-binding motif at -119 was necessary for mediating promoter activity in vitro. The goal of the present study was to confirm the functional relevance of the -119 GABP-binding site in vivo.

Priming effect of homocysteine on inducible vascular cell adhesion molecule-1 expression in endothelial cells.

Hyperhomocysteinemia is an independent risk factor for the development of atherosclerosis, as well as for arterial and venous thrombosis. However, the mechanisms through which elevated circulating levels of homocysteine cause vascular injury and promote thrombosis remain unclear. Here, we tested the hypothesis that homocysteine (Hcy) sensitizes endothelial cells to the effect of inflammatory mediators.

NADPH oxidase activity selectively modulates vascular endothelial growth factor signaling pathways.

Vascular endothelial growth factor (VEGF) and reactive oxygen species (ROS) play critical roles in vascular physiology and pathophysiology. We have demonstrated previously that NADPH oxidase-derived ROS are required for VEGF-mediated migration and proliferation of endothelial cells. The goal of this study was to determine the extent to which VEGF signaling is coupled to NADPH oxidase activity.

A three-kilobase fragment of the human Robo4 promoter directs cell type-specific expression in endothelium.

Robo4, a member of the roundabout family, is expressed exclusively in endothelial cells and has been implicated in endothelial cell migration and angiogenesis. Here we report the cloning and characterization of the human Robo4 promoter. The 3-kb 5'-flanking region directs endothelial cell-specific expression in vitro.

A novel class of vascular endothelial growth factor-responsive genes that require forkhead activity for expression.

Recently, we have shown that transient phosphorylation and inhibition of the pro-apoptotic transcription factor, forkhead, by vascular endothelial growth factor (VEGF) is essential for endothelial cell (EC) survival and proliferation. The goal of the present study was to determine whether forkhead (FKHR) also plays a positive role in agonist-mediated gene induction. Human coronary artery ECs were transduced with adenovirus overexpressing constitutively active phosphorylation-resistant triple mutant FKHR or transfected with small interference RNA (siRNA) against FKHR.

Forkhead transcription factors inhibit vascular smooth muscle cell proliferation and neointimal hyperplasia.

Vascular smooth muscle cell (VSMC) proliferation and migration contribute significantly to atherosclerosis, postangioplasty restenosis, and transplant vasculopathy. Forkhead transcription factors belonging to the FoxO subfamily have been shown to inhibit growth and cell cycle progression in a variety of cell types. We hypothesized that forkhead proteins may play a role in VSMC biology.

Familial cognitive deficits in schizophrenia.

Susceptibility to schizophrenia is considered familial, but the mechanism for transmission has not been found. Since widespread cognitive deficits have been found in patients with schizophrenia, several of these have been proposed as candidate familial endophenotypes that may or may not be predictive of who develops the illness. The current study examines these candidates in individuals from 32 families with at least 2 members having the diagnosis of chronic schizophrenia and normal comparison subjects using an extensive neuropsychological battery.

Vascular endothelial growth factor-mediated induction of manganese superoxide dismutase occurs through redox-dependent regulation of forkhead and IkappaB/NF-kappaB.

The mitochondrial antioxidant manganese superoxide dismutase (Mn-SOD) plays a critical cytoprotective role against oxidative stress. Vascular endothelial growth factor (VEGF) was shown previously to induce expression of Mn-SOD in endothelial cells by a NADPH oxidase-dependent mechanism. The goal of the current study was to determine the transcriptional mechanisms underlying this phenomenon.

Vascular endothelial growth factor activates PI3K/Akt/forkhead signaling in endothelial cells.

Objective: Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor that promotes endothelial cell (EC) survival, migration, and permeability. The forkhead transcription factors FKHR, FKHRL1, and AFX are mammalian orthologues of DAF-16, a forkhead protein that controls longevity in Caenorhabditis elegans. In this study, we examined whether VEGF is coupled to phosphatidyl inositol 3-kinase (PI3K)/Akt/forkhead in ECs.