The expression of calcium/calmodulin-dependent kinase IV (CaMKIV) was hitherto thought to be confined to the nervous system. However, a recent genome-wide analysis indicated an association between hypertension and a single-nucleotide polymorphism (rs10491334) of the human CaMKIV gene (CaMK4), which suggests a role for this kinase in the regulation of vascular tone

Abstract-Several studies underline the role of the transcription factor NF-B in the development of left cardiac hypertrophy (LVH). We have demonstrated recently that the RGS homology domain within the amino terminus of GRK5 (GRK5-NT) is able to inhibit NF-B transcription activity and its associated phenotypes. The aim of this study was to evaluate the ability of GRK5-NT to regulate LVH through the inhibition of NF-B both in vitro and in vivo. In cardiomyoblasts, GRK5-NT inhibits phenylephrine-induced transcription of both NF-B and atrial natriuretic factor promoters, assessed by luciferase assay, thus confirming a role for this protein in the regulation of cardiomyocyte hypertrophy. In vivo, we explored 2 rat models of LVH, the spontaneously hypertensive rat and the normotensive Wistar Kyoto rat exposed to chronic administration of phenylephrine. Intracardiac injection of an adenovirus encoding for GRK5-NT reduces cardiac mass in spontaneously hypertensive rats and prevents the development of phenylephrineinduced LVH in Wistar Kyoto rats. This associates with inhibition of NF-B signaling (assessed by NF-B levels), transcriptional activity and phenotypes (fibrosis and apoptosis). Such phenomenon is independent from hemodynamic changes, because adenovirus encoding for GRK5-NT did not reduce blood pressure levels in spontaneously hypertensive rats or in Wistar Kyoto rats. In conclusion, our study supports the regulation of LVH based on the GRK5-NT inhibition of the NF-B transduction signaling. (Hypertension. 2010;56:696-704.)Key Words: cardiac hypertrophy Ⅲ intracardiac injection Ⅲ spontaneously hypertensive rats Ⅲ NF-B Ⅲ transcription factors N F-B is an ubiquitously expressed transcription factor that modulates the expression of genes involved in the regulation of cell functions, such as survival, apoptosis, growth, division, innate immunity, differentiation, and cellular responses to stress, hypoxia, and ischemia. 1-4 The classic cellular model in which this factor is studied is the immune system for its central role in cytokine production. 4,5 It has been reported recently that NF-B is relevant in the development of left ventricular hypertrophy (LVH) and remodeling through mechanisms independent from inflammation. NF-B mediates hypertrophic growth of cardiomyocytes in response to G protein-coupled receptor agonists, including norepinephrine, endothelin 1, and angiotensin II. 6,7 Also, NF-B inhibition attenuates LVH in different animal models of disease. 8,9 This evidence suggests that NF-B blockade may be an effective strategy to inhibit LVH and remodeling. The family of G protein-coupled receptor kinases (GRKs) and, in particular GRK2 and GRK5, possesses the ability to bind both NF-B and its inhibitor, IB␣. 10,11 In particular, GRK5, by means of its RGS homology (RH) domain within the amino terminus, interacts with IB␣ leading to the stabilization and accumulation of the IB␣/NF-B complex in the nucleus and, consequently, to the inhibition of NF-B transcriptional activity. 11 This feature of the RH domain of GR...

In this study, we investigated the significance of β2-adrenergic receptor (β2AR) in age-related impaired insulin secretion and glucose homeostasis. We characterized the metabolic phenotype of β2AR-null C57Bl/6N mice (β2AR−/−) by performing in vivo and ex vivo experiments. In vitro assays in cultured INS-1E β-cells were carried out in order to clarify the mechanism by which β2AR deficiency affects glucose metabolism. Adult β2AR−/− mice featured glucose intolerance, and pancreatic islets isolated from these animals displayed impaired glucose-induced insulin release, accompanied by reduced expression of peroxisome proliferator–activated receptor (PPAR)γ, pancreatic duodenal homeobox-1 (PDX-1), and GLUT2. Adenovirus-mediated gene transfer of human β2AR rescued these defects. Consistent effects were evoked in vitro both upon β2AR knockdown and pharmacologic treatment. Interestingly, with aging, wild-type (β2AR+/+) littermates developed impaired insulin secretion and glucose tolerance. Moreover, islets from 20-month-old β2AR+/+ mice exhibited reduced density of β2AR compared with those from younger animals, paralleled by decreased levels of PPARγ, PDX-1, and GLUT2. Overexpression of β2AR in aged mice rescued glucose intolerance and insulin release both in vivo and ex vivo, restoring PPARγ/PDX-1/GLUT2 levels. Our data indicate that reduced β2AR expression contributes to the age-related decline of glucose tolerance in mice.

Abstract-Recently it has been demonstrated that catecholamines are produced and used by macrophages and mediate immune response. The aim of this study is to verify whether endothelial cells (ECs), which are of myeloid origin, can produce catecholamines. We demonstrated that genes coding for tyrosine hydroxylase, Dopa decarboxylase, dopamine ␤ hydroxylase (D␤H), and phenylethanolamine-N-methyl transferase, enzymes involved in the synthesis of catecholamines, are all expressed in basal conditions in bovine aorta ECs, and their expression is enhanced in response to hypoxia. Moreover, hypoxia enhances catecholamine release. To evaluate the signal transduction pathway that regulates catecholamine synthesis in ECs, we overexpressed in bovine aorta ECs either protein kinase A (PKA) or the transcription factor cAMP response element binding, because PKA/cAMP response element binding activation induces tyrosine hydroxylase transcription and activity in response to stress. Both cAMP response element binding and PKA overexpression enhance D␤H and phenylethanolamine-N-methyl transferase gene expression and catecholamine release, whereas H89, inhibitor of PKA, exerts the opposite effect, evidencing the role of PKA/cAMP response element binding transduction pathway in the regulation of catecholamine release in bovine aorta ECs. We then evaluated by immunohistochemistry the expression of tyrosine hydroxylase, Dopa decarboxylase, D␤H, and phenylethanolamine-N-methyl transferase in femoral arteries from hindlimbs of C57Bl/6 mice 3 days after removal of the common femoral artery to induce chronic ischemia. Ischemia evokes tyrosine hydroxylase, Dopa decarboxylase, D␤H, and phenylethanolamine-N-methyl transferase expression in the endothelium. Finally, the pharmacological inhibition of catecholamine release by fusaric acid, an inhibitor of D␤H, reduces the ability of ECs to form network-like structures on Matrigel matrix. In conclusion, our study demonstrates for the first time that ECs are able to synthesize and release catecholamines in response to ischemia. Key Words: catecholamines Ⅲ ischemia Ⅲ endothelium Ⅲ angiogenesis E ndothelial cells (ECs) cover the interior surface of blood vessels throughout the entire circulatory system, and they are involved in many aspects of vascular biology.1-4 Indeed, angiogenesis is a phenomenon intimately associated with EC migration and proliferation during embryonic development. 5Similarly, ECs play major roles in immune and inflammatory reactions by regulating lymphocyte and leukocyte migration into tissues by means of direct interaction with ECs.6 Moreover, ECs have an important role in the regulation of the vascular tone by releasing vasoactive agents controlling smooth muscle cell proliferation and contractility.Indeed, ECs are known to release both vasodilators (NO) and vasoconstrictors (thromboxane, platelet-derived growth factor, and endothelin 1) in response to local and circulating stimuli. [7][8][9][10][11][12][13][14] To this purpose, the endothelium is regulated in a fine way by a s...

BackgroundIntegrins are heterodimeric receptors that play a critical role in cell-cell and cell-matrix adhesion processes. Among them, αVβ3 integrin, that recognizes the aminoacidic RGD triad, is reported to be involved in angiogenesis, tissue repair and tumor growth. We have recently synthesized a new and selective ligand of αVβ3 receptor, referred to as RGDechiHCit, that contains a cyclic RGD motif and two echistatin moieties.MethodsThe aim of this study is to evaluate in vitro and in vivo the effects of RGDechiHCit. Therefore, we assessed its properties in cellular (endothelial cells [EC], and vascular smooth muscle cells [VSMC]) and animal models (Wistar Kyoto rats and c57Bl/6 mice) of angiogenesis.ResultsIn EC, but not VSMC, RGDechiHCit inhibits intracellular mitogenic signaling and cell proliferation. Furthermore, RGDechiHCit blocks the ability of EC to form tubes on Matrigel. In vivo, wound healing is delayed in presence of RGDechiHCit. Similarly, Matrigel plugs demonstrate an antiangiogenic effect of RGDechiHCit.ConclusionsOur data indicate the importance of RGDechiHCit in the selective inhibition of endothelial αVβ3 integrin in vitro and in vivo. Such inhibition opens new fields of investigation on the mechanisms of angiogenesis, offering clinical implications for treatment of pathophysiological conditions such as cancer, proliferative retinopathy and inflammatory disease.