Urotensin 2 in Kawasaki disease pathogenesis.

BackgroundGenetic variation in calcium signaling pathways is associated with Kawasaki disease (KD) susceptibility and coronary artery aneurysms (CAA). Expression quantitative trait locus analysis for KD-associated variants in calcium/sodium channel gene solute carrier family 8 member 1 (SLC8A1) revealed an effect on expression of urotensin 2 (UTS2). We speculated that UTS2 is influenced by genetic variation in SLC8A1 and contributes to disease pathogenesis.MethodsWe measured levels of UTS2 and its receptor in blood and tissues using quantitative reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemical staining.ResultsUTS2 transcript levels were higher in the whole blood of subjects with KD homozygous for three risk alleles in SLC8A1 (P=0.002-0.006). Increased levels of plasma UTS2 varied as a function of SLC8A1 genotype (P=0.008-0.04). UTS2 and UTS2 receptor were expressed in mononuclear inflammatory cells and spindle-shaped cells in the coronary arterial wall of a patient suffering from KD with CAA and in a femoral endarterectomy specimen from an adult patient with peripheral aneurysms following KD in childhood.ConclusionHost genetics influences UTS2 levels, which may contribute to inflammation and cardiovascular damage in KD.

Urotensin-II receptor stimulation of cardiac L-type Ca2+ channels requires the ßγ subunits of Gi/o-protein and phosphatidylinositol 3-kinase-dependent protein kinase C ß1 isoform.

Recent studies have demonstrated that urotensin-II (U-II) plays important roles in cardiovascular actions including cardiac positive inotropic effects and increasing cardiac output. However, the mechanisms underlying these effects of U-II in cardiomyocytes still remain unknown. We show by electrophysiological studies that U-II dose-dependently potentiates L-type Ca(2+) currents (ICa,L) in adult rat ventricular myocytes. This effect was U-II receptor (U-IIR)-dependent and was associated with a depolarizing shift in the voltage dependence of inactivation. Intracellular application of guanosine-5'-O-(2-thiodiphosphate) and pertussis toxin pretreatment both abolished the stimulatory effects of U-II. Dialysis of cells with the QEHA peptide, but not scrambled peptide SKEE, blocked the U-II-induced response. The phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin as well as the class I PI3K antagonist CH132799 blocked the U-II-induced ICa,L response. Protein kinase C antagonists calphostin C and chelerythrine chloride as well as dialysis of cells with 1,2bis(2aminophenoxy)ethaneN,N,N',N'-tetraacetic acid abolished the U-II-induced responses, whereas PKCα inhibition or PKA blockade had no effect. Exposure of ventricular myocytes to U-II markedly increased membrane PKCß1 expression, whereas inhibition of PKCß1 pharmacologically or by shRNA targeting abolished the U-II-induced ICa,L response. Functionally, we observed a significant increase in the amplitude of sarcomere shortening induced by U-II; blockade of U-IIR as well as PKCß inhibition abolished this effect, whereas Bay K8644 mimicked the U-II response. Taken together, our results indicate that U-II potentiates ICa,L through the ßγ subunits of Gi/o-protein and downstream activation of the class I PI3K-dependent PKCß1 isoform. This occurred via the activation of U-IIR and contributes to the positive inotropic effect on cardiomyocytes.

[Research progress of urotensin â ¡ and urotensin â ¡ receptor].

Urotensin II (UII) is the most potent vasoconstrictor among the identified vasoactive peptides. UII and its receptor (UT), which play varies of physiological roles, are widely expressed in central nerve system and peripheral organs. The change on the expressional level of UII/UT system has been proved to be closely correlated with pathological conditions. Therefore, UII/UT system was considered to be a potential target for treating many diseases. This review article is devoted to the latest research progress of UII/UT system in several aspects including ligand and receptor distribution, physiological activity, characteristics under pathological conditions and antagonist classification.

Urotensin II contributes to collagen synthesis and up-regulates Egr-1 expression in cultured pulmonary arterial smooth muscle cells through the ERK1/2 pathway.

AIM: The objective of this study was to investigate the effects of urotensin II (UII) treatment on the proliferation and collagen synthesis of cultured rat pulmonary arterial smooth muscle cells (PASMCs) and to explore whether these effects are mediated by mitogen-activated protein kinase (MAPK) signaling pathways and early growth response 1 (Egr-1). METHODS: The proliferation of cultured PASMCs stimulated with different doses of UII was detected by BrdU incorporation. The mRNA expression levels of procollagen I (procol I), procollagen III (procol III), extracellular regulated protein kinase 1/2 (ERK1/2), stress-stimulated protein kinase (Sapk), p38 MAPK (p38), and Egr-1 mRNA in cultured PASMCs after treatment with UII, the UII-specific antagonist urantide, and the ERK1/2 inhibitor PD98059 were detected by real-time polymerase chain reaction (PCR), and the protein expression levels of procol I, procol III, phosphorylated (p)-ERK1/2, p-Sapk, p-p38, and Egr-1 were detected by Western blotting. RESULTS: Treatment with UII increased the proliferation of cultured PASMCs in a dose-dependent manner (P<0.05). However, treatment with urantide and PD98059 inhibited the promoting effect of UII on PASMC proliferation (P<0.05). Real-time PCR analysis showed that UII up-regulated the expression of procol I, procol III, ERK1/2, Sapk, and Egr-1 mRNA (P<0.05), but not p38 mRNA. However, the up-regulating effect of UII was inhibited by PD98059 and urantide. Western blotting analysis showed that UII increased the synthesis of collagen I, collagen III, p-ERK1/2, p-Sapk, and Egr-1, and these effects also were inhibited by PD98059 and urantide (P<0.05). CONCLUSIONS: Egr-1 participates in the UII-mediated proliferation and collagen synthesis of cultured rat PASMCs via activation of the ERK1/2 signaling pathway.

Urotensin II promotes vagal-mediated bradycardia by activating cardiac-projecting parasympathetic neurons of nucleus ambiguus.

Urotensin II (U-II) is a cyclic undecapeptide that regulates cardiovascular function at central and peripheral sites. The functional role of U-II nucleus ambiguus, a key site controlling cardiac tone, has not been established, despite the identification of U-II and its receptor at this level. We report here that U-II produces an increase in cytosolic Ca(2+) concentration in retrogradely labeled cardiac vagal neurons of nucleus ambiguus via two pathways: (i) Ca(2+) release from the endoplasmic reticulum via inositol 1,4,5-trisphosphate receptor; and (ii) Ca(2+) influx through P/Q-type Ca(2+) channels. In addition, U-II depolarizes cultured cardiac parasympathetic neurons. Microinjection of increasing concentrations of U-II into nucleus ambiguus elicits dose-dependent bradycardia in conscious rats, indicating the in vivo activation of the cholinergic pathway controlling the heart rate. Both the in vitro and in vivo effects were abolished by the urotensin receptor antagonist, urantide. Our findings suggest that, in addition, to the previously reported increase in sympathetic outflow, U-II activates cardiac vagal neurons of nucleus ambiguus, which may contribute to cardioprotection.

Genetic and pharmacological manipulation of urotensin II ameliorate the metabolic and atherosclerosis sequalae in mice.

OBJECTIVE: Urotensin II (UII) is a potent vasoactive peptide that binds to the urotensin receptor-coupled receptor-14 (known as UT) and exerts a wide range of actions in humans and experimental animals. We tested the hypothesis that UII gene deletion or UT blockade ameliorate experimental atherosclerosis. METHODS AND RESULTS: We observed a significant reduction in weight gain, visceral fat, blood pressure, circulating plasma lipids, and proatherogenic cytokines and improvement of glucose tolerance in UII knockout mice compared with wild type (P<0.05). Deletion of UII after an apolipoprotein E knockout resulted in a significant reduction in serum cytokines, adipokines, and aortic atherosclerosis compared with apolipoprotein E knockout mice. Similarly, treatment of apolipoprotein E knockout mice fed on high-fat diet with the UT antagonist SB657510A reduced weight gain, visceral fat, and hyperlipidemia and improved glucose tolerance (P<0.05) and attenuated the initiation and progression of atherosclerosis. The UT antagonist also decreased aortic extracellular signal-regulated kinase 1/2 phosphorylation and oxidant formation and serum level of cytokines (P<0.05). CONCLUSIONS: These findings demonstrate for the first time the role of UII gene deletion in atherosclerosis and suggest that the use of pharmaceutical agents aimed at blocking the UII pathway may provide a novel approach in the treatment of atherosclerosis and its associated precursors such as obesity, hyperlipidemia, diabetes mellitus, and hypertension.

Serum urotensin II levels in patients with non-dipper hypertension.

Hypertension terms "dipper" and "non-dipper" are propounded by the change that occurs during ambulatory blood pressure (BP) monitoring. The purpose of this study is to present whether the serum urotensin II levels are different in patients with dipper and non-dipper hypertension and to put forward the effects causing this difference, if there are any. Patients recently diagnosed with hypertension were included in the study. With ambulatory BP monitoring, 81 patients with high BP were divided into two groups, dipper (n = 40) and non-dipper (n = 41). Serum urotensin II levels were analyzed by ELISA method. Serum urotensin II levels were higher in patients with non-dipper hypertension than in patients with dipper hypertension (204 [106-533] vs. 140 [96-309], P = .004). There was a positive correlation between total systolic BP and serum urotensin II levels (r = 0.408 and P = .009), but the relation in the non-dipper hypertension group was not significant (r = 0.194 and P = .2). In conclusion, serum urotensin II levels were higher in non-dipper HT patients than dipper HT patients. This higher urotensin II level might be responsible for poor prognoses.

Roles of human urotensin II in volume resistance hypertension in peritoneal dialysis patients.

Human urotensin II (hUII) is a newly discovered substance that can dilate small blood vessels to decrease the blood pressure (BP). Our previous studies showed that some volume-overloaded patients on peritoneal dialysis can maintain normal BP (congestive heart failure excluded), suggesting that these patients have volume resistance capacity. This study is to investigate whether hUII plays an important role in this subgroup of patients on peritoneal dialysis. In this study, 105 patients on continuous ambulatory peritoneal dialysis were enrolled. Volume load was evaluated by the overhydration (OH) value obtained by bioimpedance analysis. OH < 2.0 kg was defined as normal volume (NV), and OH ≥ 2.0 kg as high volume (HV). Systolic blood pressure (SBP) <130 mmHg was defined as normotension (NT) and ≥130 mmHg as hypertension (HT). The patients were thus divided into four subgroups: (1) normotension with normal volume (NT-NV), (2) normotension with high volume (NT-HV), (3) normal volume with hypertension (HT-NV), and (4) high volume with hypertension (HT-HV). hUII was measured using radioimmunoassay method. hUII was significantly higher in normal SBP group than that in high SBP group (p < 0.05). hUII was higher in the NT-HV group compared with that in the HT-HV group (p < 0.05). Our study suggests that hUII may be involved in the pathogenesis of the volume resistance HT in peritoneal dialysis patients.

EGFR trans-activation by urotensin II receptor is mediated by ß-arrestin recruitment and confers cardioprotection in pressure overload-induced cardiac hypertrophy.

Urotensin II (UTII) and its seven trans-membrane receptor (UTR) are up-regulated in the heart under pathological conditions. Previous in vitro studies have shown that UTII trans-activates the epidermal growth factor receptor (EGFR), however, the role of such novel signalling pathway stimulated by UTII is currently unknown. In this study, we hypothesized that EGFR trans-activation by UTII might exert a protective effect in the overloaded heart. To test this hypothesis, we induced cardiac hypertrophy by transverse aortic constriction (TAC) in wild-type mice, and tested the effects of the UTII antagonist Urantide (UR) on cardiac function, structure, and EGFR trans-activation. After 7 days of pressure overload, UR treatment induced a rapid and significant impairment of cardiac function compared to vehicle. In UR-treated TAC mice, cardiac dysfunction was associated with reduced phosphorylation levels of the EGFR and extracellular-regulated kinase (ERK), increased apoptotic cell death and fibrosis. In vitro UTR stimulation induced membrane translocation of ß-arrestin 1/2, EGFR phosphorylation/internalization, and ERK activation in HEK293 cells. Furthermore, UTII administration lowered apoptotic cell death induced by serum deprivation, as shown by reduced TUNEL/Annexin V staining and caspase 3 activation. Interestingly, UTII-mediated EGFR trans-activation could be prevented by UR treatment or knockdown of ß-arrestin 1/2. Our data show, for the first time in vivo, a new UTR signalling pathway which is mediated by EGFR trans-activation, dependent by ß-arrestin 1/2, promoting cell survival and cardioprotection.

Immunomodulatory role of urotensins in teleost Channa punctatus.

The present study, for the first time in ectothermic vertebrates, reports the immunoregulatory role of urotensins I and II (UI and UII). Urotensins decreased the phagocytosis and nitrite production by splenic phagocytes. On superoxide production, UI had stimulatory while UII showed inhibitory effect. UI exerted its effect on phagocytes through corticotrophin-releasing factor (CRF) receptor as its non-specific antagonist astressin completely blocked the effect of UI on phagocytosis, nitrite release and superoxide production. Among the antagonists for specific CRF receptor 1 and 2, only CRF receptor 1 antagonist NBI 27914 abolished the effect of urotensin I. On the other hand, UII mediated its effect through urotensin receptor (UT receptor) since its antagonist urantide antagonized the effect of UII on phagocytosis, superoxide and nitrite release. These findings provide the direct evidence on physiological role of UI and UII through CRF receptor 1 and UT receptor, respectively in control of fish immune responses.

Role of urotensin II in health and disease.

Urotensin II (UII) is an 11 amino acid cyclic peptide originally isolated from the goby fish. The amino acid sequence of UII is exceptionally conserved across most vertebrate taxa, sharing structural similarity to somatostatin. UII binds to a class of G protein-coupled receptor known as GPR14 or the urotensin receptor (UT). UII and its receptor, UT, are widely expressed throughout the cardiovascular, pulmonary, central nervous, renal, and metabolic systems. UII is generally agreed to be the most potent endogenous vasoconstrictor discovered to date. Its physiological mechanisms are similar in some ways to other potent mediators, such as endothelin-1. For example, both compounds elicit a strong vascular smooth muscle-dependent vasoconstriction via Ca(2+) release. UII also exerts a wide range of actions in other systems, such as proliferation of vascular smooth muscle cells, fibroblasts, and cancer cells. It also 1) enhances foam cell formation, chemotaxis of inflammatory cells, and inotropic and hypertrophic effects on heart muscle; 2) inhibits insulin release, modulates glomerular filtration, and release of catecholamines; and 3) may help regulate food intake and the sleep cycle. Elevated plasma levels of UII and increased levels of UII and UT expression have been demonstrated in numerous diseased conditions, including hypertension, atherosclerosis, heart failure, pulmonary hypertension, diabetes, renal failure, and the metabolic syndrome. Indeed, some of these reports suggest that UII is a marker of disease activity. As such, the UT receptor is emerging as a promising target for therapeutic intervention. Here, a concise review is given on the vast physiologic and pathologic roles of UII.

Urotensin II: a novel target in human corpus cavernosum.

INTRODUCTION: Urotensin II (U-II) is a cyclic peptide originally isolated from the teleost neurosecretory system and subsequently identified in other species, including man. U-II was identified as the natural ligand of an orphan G-protein coupled receptor (UT receptor). U-II and UT receptor are expressed in a variety of peripheral organs and especially in cardiovascular tissue. U-II caused both constrictor and vasodilator effect, depending by vascular bed. The in vivo functional consequences of U-II on the cardiovascular hemodynamics are not clearly understood. AIM: To investigate the presence of UT receptor and the effect of U-II in human corpus cavernosum (HCC) strips. To evaluate the effect of U-II in vivo in anesthetized rats. METHODS: UT receptor expression as protein and as mRNA were assessed by Western blot and reverse transcriptase polymerase chain reaction. Next, the UT receptor localization was evaluated by immunohistochemical analysis. By using HCC strips, with or without endothelium, the effect of U-II (0.1 nM-10 microM) was evaluated. In order to asses the nitric oxide (NO) involvement, the strips were incubated with N (G)-nitro-L-arginine methyl ester (NO synthase inhibitor, 100 microM). U-II (0.1, 0.3, 1.0 nmol/rat) effect in vivo was studied in anesthetized rats by monitoring the intracavernous and systemic blood pressure. MAIN OUTCOME MEASURES: HCC expresses the UT receptor and its activation, by UII, causes an endothelium- and NO-dependent relaxation. RESULTS: UT receptor is expressed in human and rat corpus cavernosum. In HCC UT receptor is localized on endothelial cells. U-II significantly relaxed HCC strips in endothelium- and -NO-dependent fashion. The peptide caused a significant increase in intracavernous pressure in anesthetized rats. CONCLUSION: This study demonstrates that UT receptor is expressed on the endothelium of HCC. U-II/UT receptor system is involved in HCC function and it involves endothelium and NO pathway. Thus, U-II/UT receptor pathway could be involved in erectile function.

Urotensin II activates sarcolemmal Na+/H+ exchanger in adult rat ventricular myocytes.

OBJECTIVES: Our aims in the present study were (1) to determine the effects of urotensin II (UT-II) on the sarcolemmal Na/H exchanger (NHE1) activity, and (2) to investigate possible kinase pathways for UT-II-mediated NHE1 stimulation. METHODS: In single rat ventricular myocytes (n = 5-10/group) loaded with the pH-sensitive fluoroprobe carboxy-seminaphthorhodafluor-1, acid efflux rates (JH) were determined as an index of NHE1 activity by rate of recovery of intracellular pH (pHi) from NH4Cl-induced acidosis and the intrinsic buffering power. Phosphorylation of extracellular signal-regulated kinase (ERK), a key kinase of NHE1 activation, was determined by Western blot analysis. RESULTS: JH increased by 31%-71% relative to control in the presence of 100 nmol/L UT-II at pHi range of 6.6-7.0. Stimulation of NHE1 activity by UT-II was abolished by inhibitors of phospholipase C, protein kinase C, and ERK kinase; 2-nitro-4-carboxyphenil-N,N-diphenilcarbamate at 100 micromol/L, GF109203X at 300 nmol/L, and PD98059 at 50 micromol/L, respectively. Moreover, UT-II at 100 nmol/L produced a significant increase in cellular ERK1/2 phosphorylation, which was also inhibited by those inhibitors. CONCLUSIONS: Our study was the first to demonstrate that UT-II activates the cardiac sarcolemmal NHE1 and that the phenomenon may involve, at least in part, the phospholipase C-protein kinase C-ERK pathway.

Effects of exogenous urotensin II on vascular remodelling after balloon injury.

1. Urotensin II (U-II) is a powerful vasoconstrictor peptide that stimulates cell proliferation. However, the systemic effects of U-II on cellular and extracellular matrix responses of vessel walls have not been investigated. The aim of the present study was to determine the effect of exogenous U-II on arterial neointimal hyperplasia after balloon injury. 2. A stenosis model of the thoracic aorta after balloon injury was established in male Wistar rats. Rats were divided into three groups (n = 5 in each): (i) uninjured; (ii) injured for 21 days; and (iii) injured and then treated with U-II (1 nmol/kg per h) via an osmotic minipump for 21 days. Another group of rats were killed on Days 7 and 14 after balloon injury for the analysis of in vitro collagen synthesis and secretion with U-II treated by [(3)H]-proline incorporation and determination of [(3)H]-hydroxyproline radioactivity, respectively. 3. Urotensin II immunoreactivity was 1.74-fold higher in vessels injured for 21 days than in uninjured vessels and mRNA levels of the urotensin UT receptor were upregulated by 55% following injury. After U-II treatment, the mRNA levels of the UT receptor were further upregulated (by 40%). In addition, U-II treatment increased the intimal area of injured aortas (13 +/- 5 vs 7 +/- 2% in group iii and ii, respectively), as well as increasing collagen content and cell proliferation. Protein levels of matrix metalloproteinase 1 were decreased in U-II-treated rats. In vitro, U-II treatment increased collagen synthesis and secretion in uninjured vessels in a concentration-dependent manner (10(-10), 10(-9) and 10(-8) mol/L U-II), especially in injured aortas on Day 7 after injury. 4. In conclusion, exogenous U-II may upregulate mRNA levels of the UT receptor, as well as increase collagen and cell proliferation, all of which would contribute to intimal hyperplasia after angioplasty.

Expression and functional role of urotensin-II and its receptor in the adrenal cortex and medulla: novel insights for the pathophysiology of primary aldosteronism.

CONTEXT: The involvement of urotensin II, a vasoactive peptide acting via the G protein-coupled urotensin II receptor, in arterial hypertension remains contentious. OBJECTIVE: We investigated the expression of urotensin II and urotensin II receptor in adrenocortical and adrenomedullary tumors and the functional effects of urotensin II receptor activation. DESIGN: The expression of urotensin II and urotensin II receptor was measured by real time RT-PCR in aldosterone-producing adenoma (n = 22) and pheochromocytoma (n = 10), using histologically normal adrenocortical (n = 6) and normal adrenomedullary (n = 5) tissue as control. Urotensin II peptide and urotensin II receptor protein were investigated with immunohistochemistry and immunoblotting. To identify urotensin II-related and urotensin II receptor-related pathways, a whole transcriptome analysis was used. The adrenocortical effects of urotensin II receptor activation were also assessed by urotensin II infusion with/without the urotensin II receptor antagonist palosuran in rats. RESULTS: Urotensin II was more expressed in pheochromocytoma than in aldosterone-producing adenoma tissue; the opposite was seen for the urotensin II receptor expression. Urotensin II receptor activation in vivo in rats enhanced (by 182 +/- 9%; P < 0.007) the adrenocortical expression of immunoreactive aldosterone synthase. CONCLUSIONS: Urotensin II is a putative mediator of the effects of the adrenal medulla and pheochromocytoma on the adrenocortical zona glomerulosa. This pathophysiological link might account for the reported causal relationship between pheochromocytoma and primary aldosteronism.

Urotensin II induces transactivation of the epidermal growth factor receptor via transient oxidation of SHP-2 in the rat renal tubular cell line NRK-52E.

Urotensin-II (UII) is a potent vasoactive peptide that has been implicated in cardiac fibrosis and renal diseases. However, the role played by UII in renal tissues is largely unknown. In this study, we investigated the effects of human UII (hUII) on rat renal proximal tubular cells of the NRK-52E line and the role of Src homology 2-containing phosphotyrosine phosphatase (SHP-2) in the hUII-induced transactivation of the epidermal growth factor receptor (EGFR). Exposure to hUII at low concentrations significantly induced proliferation in NRK-52E cells; this effect was inhibited by treatment with an ERK1/2 inhibitor (PD98059). UII treatment increased the phosphorylation of EGFR and induced the generation of reactive oxygen species (ROS). Treatment of the ROS scavenger N-acetyl-cysteine (NAC) inhibited EGFR transactivation and ERK phosphorylation induced by hUII. SHP-2 was found to interact with EGFR and be transiently oxidized following the hUII treatment. In SHP-2 knockdown cells, UII-induced phosphorylation of EGFR was less influenced by NAC, and significantly suppressed by heparin binding (HB)-EGF neutralizing antibody. Our data suggest that the ROS-mediated oxidation of SHP-2 is essential for the hUII-induced mitogenic pathway in NRK-52E cells.

Ontogeny of the corticotropin-releasing factor system in zebrafish.

The corticotropin-releasing factor (CRF) system in fish functions to maintain homeostasis during stress in part by regulating cortisol production via the hypothalamus-pituitary-interrenal (HPI) axis. Towards understanding the role of the CRF system in vertebrate development, we describe the ontogeny of the CRF system, cortisol, and the stress response in the zebrafish, Danio rerio. Early embryonic expression of mRNA encoding CRF, urotensin I (UI), CRF-binding protein (CRF-BP), and two CRF receptors (CRF-R1 and CRF-R2) suggest a function in the early organization of the developing embryo. The expression patterns of CRF, UI, and CRF-BP in the larval brain are consistent with the adult distribution patterns for these genes and support HPI-axis independent functions. The relative amounts of CRF and UI mRNA in the heads and tails of developing and adult zebrafish suggest that CRF functions primarily in the brain while UI also plays an important role in the caudal neurosecretory system. The amount of cortisol in developing zebrafish is low and relatively constant through the first 6 days of development. The commencement of feeding after 4 dpf, however, significantly increases basal cortisol production. Finally, we show that zebrafish larvae are able to respond to an osmotic stressor as early as 3 dpf. Overall, results from this study establish the zebrafish as a model species for research on stress during ontogeny and offer new insights into an HPI-axis independent function for the CRF system during embryogenesis.

Chronic urotensin II infusion enhances macrophage foam cell formation and atherosclerosis in apolipoprotein E-knockout mice.

OBJECTIVE: Our recent studies have indicated that urotensin II, the most potent vasoconstrictor peptide identified to date, potentiates human macrophage foam cell formation and vascular smooth muscle cell proliferation, and its levels are increased in the plasma of hypertensive patients with carotid atherosclerotic plaques. In the present study, we investigated the enhancing effect of urotensin II on atherosclerosis in apolipoprotein E-knockout mice and its suppression by 4-aminoquinoline, an urotensin II receptor-selective antagonist. METHODS: Urotensin II, urotensin II + 4-aminoquinoline, or vehicle was infused for 4 weeks through an osmotic mini-pump into 9-week-old apolipoprotein E-knockout mice on a high-fat diet. Aortic atherosclerosis and foam cell formation in exudate peritoneal macrophages were examined. RESULTS: Atherosclerotic lesions as well as plasma levels of urotensin II, reactive oxygen species, and oxidized low-density lipoprotein and oxidized low-density lipoprotein-induced foam cell formation were significantly greater in urotensin II-infused mice than vehicle-infused controls. Western blotting analysis showed increased expression of scavenger receptors (CD36 and scavenger receptor class A) and acyl-CoA:cholesterol acyltransferase-1 in these macrophages. Increases in these parameters were significantly reduced by addition of 4-aminoquinoline. In apolipoprotein E-knockout mice even without urotensin II infusion, the treatment with 4-aminoquinoline for 8 weeks significantly prevented the development of atherosclerotic lesions. CONCLUSION: Our results provide the first evidence that increased plasma urotensin II level stimulates oxidized low-density lipoprotein and reactive oxygen species production and macrophage foam cell formation via increased expression of CD36, scavenger receptor class A, and acyl-CoA:cholesterol acyltransferase-1, contributing to the development of atherosclerosis in apolipoprotein E-deficient mice. Urotensin II receptor antagonism may be a promising therapeutic strategy against atherosclerosis.

Urotensin II induces phenotypic differentiation, migration, and collagen synthesis of adventitial fibroblasts from rat aorta.

BACKGROUND: Urotensin II is a new potent vasoconstrictor. Nevertheless, little is known about its effects on the activation of adventitial fibroblasts. OBJECTIVE: To explore the effects of urotensin II on phenotypic differentiation, migration, and collagen I synthesis of rat aortic adventitial fibroblasts. METHODS: Growth-arrested adventitial fibroblasts were incubated in serum-free medium with urotensin II and some inhibitors of signal transduction pathways. The alpha-smooth muscle-actin expression, collagen I synthesis and migration of adventitial fibroblasts induced by urotensin II were evaluated by western blot, enzyme-linked immunosorbant assay, and the transwell technique, respectively. RESULTS: Urotensin II induced the [alpha]-smooth muscle-actin expression in a dose-dependent and time-dependent manner, with maximal effect at a concentration of 10(-8) mol/l at 24 h (79.9%); it also caused a dose-dependent increase in collagen I synthesis, with maximal effect at a concentration of 10(-7) mol/l (42.6%). The Ca2+ channel blocker nicardipine (10(-5) mol/l), protein kinase C inhibitor H7 (10(-5) mol/l), Rho protein kinase inhibitor Y-27632 (10(-5) mol/l), calcineurin inhibitor cyclosporine A (10(-5) mol/l), and mitogen-activated protein kinase inhibitor PD98059 (10(-5) mol/l) inhibited urotensin II-induced increases in [alpha]-smooth muscle-actin expression and collagen synthesis. Meanwhile, urotensin II stimulated the migration of adventitial fibroblasts dose dependently, with maximal effect at a concentration of 10(-8) mol/l, which was 5.7-fold greater than that of the control. This effect could also be inhibited by PD98059, H7, cyclosporine A, and Y-27632 but not nicardipine. CONCLUSION: Urotensin II may stimulate adventitial fibroblasts phenotypic conversion, migration, and collagen I synthesis through the protein kinase C, mitogen-activated protein kinase, calcineurin, Rho kinase, and/or Ca2+ signal transduction pathways, contributing to the development of vascular remodeling through adventitial fibroblasts activation.

Urotensin II is an autocrine/paracrine growth factor for aortic adventitia of rat.

Urotensin II (UII) is a potent vasoconstrictive peptide; however, its significance in vascular adventitia has not been clearly elucidated. In this study, rat aortic adventitia showed mRNA expression and immunoreactivity of UII and its receptor (UT). Moreover, radioligand-binding assay showed that maximum binding capacity (Bmax) of [(125)I]-UII was higher in adventitia than in media (28.60+/-1.94 vs. 20.21+/-1.11 fmol/mg, P<0.01), with no difference in binding affinity (dissociation constant [Kd] 4.27+/-0.49 vs. 4.60+/-0.40 nM, P>0.05). Furthermore, in cultured adventitial fibroblasts, UII stimulated DNA synthesis, collagen synthesis and secretion in a concentration-dependent manner. These effects were inhibited by the UII receptor antagonist urantide (10(-6) mol/l), Ca(2+) channel blocker nicardipine (10(-5) mol/l), protein kinase C inhibitor H7 (10(-6) mol/l), and mitogen-activated protein kinase inhibitor PD98059 (10(-6) mol/l) but not the phosphatidyl inositol-3 kinase inhibitor wortmannin (10(-7) mol/l). UII may act as an autocrine/paracrine factor through its receptor and the Ca(2+) channel, protein kinase C, and mitogen-activated protein kinase signal transduction pathways, in the pathogenesis of vascular remodeling by activating vascular adventitia.