Urotensin-2 promotes collagen synthesis via ERK1/2-dependent and ERK1/2-independent TGF-β1 in neonatal cardiac fibroblasts

Effects of Thymoquinone on Urotensin-II and TGF-β1 Levels in Model of Osteonecrosis in Rats

Objectives: We aimed to investigate the therapeutic effects of thymoquinone (TMQ) treatment in osteonecrotic rats by evaluating protein levels, osteonecrosis (ON) levels, fatty acid degeneration, oxidative status, and plasma levels of Urotensin-II (U-II) and transforming growth factor-beta (TGF-β1). Materials and Methods: 40 weight-matched adult male Wistar rats were grouped as control (n = 10), methylprednisolone acetate (MPA) (n = 10), thymoquinone (TMQ) (n = 10), and MPA + TMQ (n = 10). To induce ON, 15-week-old animals were subcutaneously injected with MPA at a dose of 15 mg/kg twice weekly for 2 weeks. TMQ was injected into 15-week-old rats via gastric gavage at a dose of 80 mg/kg per day for 4 weeks. The rats in the MPA + TMQ group were administered TMQ 2 weeks before the MPA injection. At the end of the treatments, cardiac blood samples and femur samples were collected for biochemical and histological evaluations. Results: In the control and TMQ groups, no ON pattern was observed. However, in tissues exposed to MPA, TMQ treatment resulted in significantly decreased ON levels compared to the MPA group. The number of cells that were positive for 8-OHdG and 4-HNE was significantly lower in the MPA + TMQ group than in the MPA group (p < 0.05). In terms of TGF-β1 and U-II levels, we observed that both TGF-β1 (367.40 ± 23.01 pg/mL vs. 248.9 ± 20.12 pg/mL) and U-II protein levels (259.5 ± 6.0 ng/mL vs. 168.20 ± 7.90 ng/mL) increased significantly in the MPA group compared to the control group (p < 0.001). Furthermore, TGF-β1 (293.50 ± 14.18 pg/mL) and U-II (174.80 ± 4.2 ng/mL) protein levels were significantly decreased in the MPA + TMQ group compared to the MPA group (p < 0.05 and p < 0.01, respectively). There was a statistically positive correlation (p < 0.05) between the TGF-β1 and U-II protein levels in all groups (p = 0.002, rcontrol = 0.890; p = 0.02, rTMQ = 0.861; p = 0.024, rMPA+TMQ = 0.868) except for the MPA group (p < 0.03, rMedrol = -0.870). Conclusions: As far as we know, this is the first study to demonstrate the curative functions of TMQ on ON by causing a correlated decrease in the expression of U-II and TGF-β1 in the femoral heads of rats.

Urotensin II Induces Cardiac Fibrosis through the TGF-β/Smad Signaling Pathway during the Development of Cardiac Hypertrophy

Myocardial fibrosis is an important pathological phenomenon of cardiac remodeling that is induced by hypertension, myocardial ischemia, valvular heart disease, hypertrophic cardiomyopathy, and other heart diseases and can progress to heart failure. Urotensin II (UII) is regarded as a cardiovascular autacoid/hormone that is not only the most potent vasoconstrictor in mammals but also involved in cardiac remodeling. However, the molecular mechanisms responsible for UII-induced cardiac fibrosis have not yet been fully elucidated. Therefore, we aimed to investigate the effect of UII on myocardial fibrosis in cardiac hypertrophy and the mechanism of UII-induced cardiac fibrosis. Cardiac tissue from mice subjected to Transverse aortic constriction (TAC) was collected. Cardiac hypertrophy, myocardial fibrosis, and the expression of UII protein were assessed using echocardiography and pathological and molecular biological analyses. The effect of UII on fibrosis was evaluated in UII-treated mice and isolated rat primary cardiac fibroblasts, and the results indicated that UII induced significant myocardial fibrosis and increases in the proliferation and fibrotic responses both in mice and cultured fibroblasts. Mechanistically, UII treatment induced activation of the TGF-β/Smad signaling pathway, which was suppressed by the UII receptor antagonist. In conclusion, UII plays critical roles in cardiac fibrosis by modulating the TGF-β/Smads signaling pathway, which may be a promising therapeutic target in hypertrophic cardiomyopathy and related problems, such as cardiac remodeling and heart failure.

Identification and signaling characterization of four urotensin II receptor subtypes in the western clawed frog, Xenopus tropicalis

Urotensin II (UII) is involved, via the UII receptor (UTR), in many physiological and pathological processes, including vasoconstriction, locomotion, osmoregulation, immune response, and metabolic syndrome. In silico studies have revealed the presence of four or five distinct UTR (UTR1-UTR5) gene sequences in nonmammalian vertebrates. However, the functionality of these receptor subtypes and their associations to signaling pathways are unclear. In this study, full-length cDNAs encoding four distinct UTR subtypes (UTR1, UTR3, UTR4, and UTR5) were isolated from the western clawed frog (Xenopus tropicalis). In functional analyses, homologous Xenopus UII stimulation of cells expressing UTR1 or UTR5 induced intracellular calcoum mobilization and phosphorylation of extracellular signal-regulated kinase 1/2. Cells expressing UTR3 or UTR4 did not show this response. Furthermore, UII induced the phosphorylation of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) through the UII-UTR1/5 system. However, intracellular cAMP accumulation was not observed, suggesting that UII-induced CREB phosphorylation is caused by a signaling pathway different from that involving Gs protein. In contrast, the administration of UII to cells increased the phosphorylation of guanine nucleotide exchange factor-H1 (GEF-H1) and myosin light chain 2 (MLC2) in all UTR subtypes. These results define four distinct UTR functional subtypes and are consistent with the molecular evolution of UTR subtypes in vertebrates. Further understanding of signaling properties associated with UTR subtypes may help in clarifying the functional roles associated with UII-UTR interactions in nonmammalian vertebrates.

A combined CaMKII inhibition and mineralocorticoid receptor antagonism via eplerenone inhibits functional deterioration in chronic pressure overloaded mice

In the diseased and remodelled heart, increased activity and expression of Ca^2+/ calmodulin-dependent protein kinase II (CaMKII), an excess of fibrosis, and a decreased electrical coupling and cellular excitability leads to disturbed calcium homeostasis and tissue integrity. This subsequently leads to increased arrhythmia vulnerability and contractile dysfunction. Here, we investigated the combination of CaMKII inhibition (using genetically modified mice expressing the autocamtide-3-related-peptide (AC3I)) together with eplerenone treatment (AC3I-Epler) to prevent electrophysiological remodelling, fibrosis and subsequent functional deterioration in a mouse model of chronic pressure overload. We compared AC3I-Epler mice with mice only subjected to mineralocorticoid receptor (MR) antagonism (WT-Epler) and mice with only CaMKII inhibition (AC3I-No). Our data show that a combined CaMKII inhibition together with MR antagonism mitigates contractile deterioration as was manifested by a preservation of ejection fraction, fractional shortening, global longitudinal strain, peak strain and contractile synchronicity. Furthermore, patchy fibrosis formation was reduced, potentially via inhibition of pro-fibrotic TGF-β/SMAD3 signalling, which related to a better global contractile performance and a slightly depressed incidence of arrhythmias. Furthermore, the level of patchy fibrosis appeared significantly correlated to eplerenone dose. The addition of eplerenone to CaMKII inhibition potentiates the effects of CaMKII inhibition on pro-fibrotic pathways. As a result of the applied strategy, limiting patchy fibrosis adheres to a higher synchronicity of contraction and an overall better contractile performance which fits with a tempered arrhythmogenesis.

An investigation into the expression and mechanism of action of urotensin II in chronic pressure-overloaded rat hearts

The present study aimed to investigate the role and mode of action of urotensin II (U II) in the occurrence and progression of cardiac fibrosis in a pressure-overload rat model. Coarctation of the abdominal aorta was used to establish an animal model, and postoperative echocardiography, hemodynamic detection, hematoxylin and eosin staining, Masson staining and immunohistochemistry were performed to assess the changes in cardiac function and pathology. The expression levels of U II, G-protein-coupled receptor 14 and collagen (Col) I and Col III in the myocardial tissues were also analyzed. Neonatal rat fibroblasts were isolated, cultured and subsequently, generations 3–5 were randomly divided into different groups for the detection of Col I and Col III levels by enzyme-linked immunosorbent assay and western blotting. The protein expression levels were markedly increased in the model group, and this increase correlated with an increase in myocardial fibrosis. In cultured neonatal rat fibroblast cells, 10⁻⁸ mol/l U II significantly stimulated the synthesis of Col I and Col III (P<0.01) compared with the control group. Compared with the U II group, the administration of KT5720 (1 mol/l) or SB-611812 (1 mol/l) significantly reduced the synthesis and expression levels of Col I and Col III (P<0.05). U II may exert an important role in the process of myocardial fibrosis in chronic pressure-overload rats, and the cyclic adenosine monophosphate-protein kinase A signaling pathway may be partly involved in this process.

Unravelling osteoarthritis-related synovial fibrosis: a step closer to solving joint stiffness

Synovial fibrosis is often found in OA, contributing heavily to joint pain and joint stiffness, the main symptoms of OA. At this moment the underlying mechanism of OA-related synovial fibrosis is not known and there is no cure available. In this review we discuss factors that have been reported to be involved in synovial fibrosis. The aim of the study was to gain insight into how these factors contribute to the fibrotic process and to determine the best targets for therapy in synovial fibrosis. In this regard, the following factors are discussed: TGF-β, connective tissue growth factor, procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2, tissue inhibitor of metalloproteinase 1, A disintegrin and metalloproteinase domain 12, urotensin-II, prostaglandin F2α and hyaluronan.

International Union of Basic and Clinical Pharmacology. XCII. Urotensin II, urotensin II-related peptide, and their receptor: from structure to function

Urotensin II (UII) is a cyclic neuropeptide that was first isolated from the urophysis of teleost fish on the basis of its ability to contract the hindgut. Subsequently, UII was characterized in tetrapods including humans. Phylogenetic studies and synteny analysis indicate that UII and its paralogous peptide urotensin II-related peptide (URP) belong to the somatostatin/cortistatin superfamily. In mammals, the UII and URP genes are primarily expressed in cholinergic neurons of the brainstem and spinal cord. UII and URP mRNAs are also present in various organs notably in the cardiovascular, renal, and endocrine systems. UII and URP activate a common G protein-coupled receptor, called UT, that exhibits relatively high sequence identity with somatostatin, opioid, and galanin receptors. The UT gene is widely expressed in the central nervous system (CNS) and in peripheral tissues including the retina, heart, vascular bed, lung, kidney, adrenal medulla, and skeletal muscle. Structure-activity relationship studies and NMR conformational analysis have led to the rational design of a number of peptidic and nonpeptidic UT agonists and antagonists. Consistent with the wide distribution of UT, UII has now been shown to exert a large array of biologic activities, in particular in the CNS, the cardiovascular system, and the kidney. Here, we review the current knowledge concerning the pleiotropic actions of UII and discusses the possible use of antagonists for future therapeutic applications.

Urotensin II upregulates migration and cytokine gene expression in leukocytes of the African clawed frog, Xenopus laevis

Urotensin II (UII) exhibits diverse physiological actions including vasoconstriction, locomotor activity, osmoregulation, and immune response via the UII receptor (UTR) in mammals. However, in amphibians the function of the UII-UTR system remains unknown. In the present study, we investigated the potential immune function of UII using leukocytes isolated from the African clawed frog, Xenopus laevis. Stimulation of male frogs with lipopolysaccharide increased mRNA expression of UII and UTR in leukocytes, suggesting that inflammatory stimuli induce activation of the UII-UTR system. Migration assays showed that both UII and UII-related peptide enhanced migration of leukocytes in a dose-dependent manner, and that UII effect was inhibited by the UTR antagonist urantide. Inhibition of Rho kinase with Y-27632 abolished UII-induced migration, suggesting that it depends on the activation of RhoA/Rho kinase. Treatment of isolated leukocytes with UII increased the expression of several cytokine genes including tumor necrosis factor-α, interleukin-1β, and macrophage migration inhibitory factor, and the effects were abolished by urantide. These results suggest that in amphibian leukocytes the UII-UTR system is involved in the activation of leukocyte migration and cytokine gene expression in response to inflammatory stimuli.

Urotensin II (U-II), a novel cyclic peptide, possibly associated with the pathophysiology of osteoarthritis

Synovial fibrosis is one of the main outcomes of osteoarthritis. Some authors have reported that urotensin-II (U-II) may cause pathologic fibrosis in cardiovascular system, lung and liver. However there are no previous reports available in the literature about its relationship with the synovial fibrosis in osteoarthritis. The aim of this study was to compare the U-II levels in knee synovial fluids obtained from osteoarthritic and non-osteoarthritic patients. Two groups were created, the osteoarthritis group and non-osteoarthritic control group. The control group was consisted of patients who underwent arthroscopic surgery for other reasons than cartilage disorders. In the osteoarthritis group all patients had grade 4 primer degenerative osteoarthritis and were treated with total knee arthroplasty. Minimum 1 mL knee synovial fluids were obtained during operation. Levels of U-II were measured by using ELISA kit U-II levels were significantly higher in the osteoarthritic group than that in the control group. No correlation was found between U-II levels and age. In conclusion, the significantly high U-II levels in the knee synovial fluid of osteoarthritic patients supported our hypothesis that "U-II may be associated with the synovial fibrosis in osteoarthritis".

Lactosylceramide promotes hypertrophy through ROS generation and activation of ERK1/2 in cardiomyocytes

Hypertrophy is central to several heart diseases; however, not much is known about the role of glycosphingolipids (GSLs) in this phenotype. Since GSLs have been accorded several physiological functions, we sought to determine whether these compounds affect cardiac hypertrophy. By using a rat cardiomyoblast cell line, H9c2 cells and cultured primary neonatal rat cardiomyocytes, we have determined the effects of GSLs on hypertrophy. Our study comprises (a) measurement of [(3)H]-leucine incorporation into protein, (b) measurement of cell size and morphology by immunofluorescence microscopy and (c) real-time quantitative mRNA expression assay for atrial natriuretic peptide and brain natriuretic peptide. Phenylephrine (PE), a well-established agonist of cardiac hypertrophy, served as a positive control in these studies. Subsequently, mechanistic studies were performed to explore the involvement of various signaling transduction pathways that may contribute to hypertrophy in these cardiomyocytes. We observed that lactosylceramide specifically exerted a concentration- (50-100 µM) and time (48 h)-dependent increase in hypertrophy in cardiomyocytes but not a library of other structurally related GSLs. Further, in cardiomyocytes, LacCer generated reactive oxygen species, stimulated the phosphorylation of p44 mitogen activated protein kinase and protein kinase-C, and enhanced c-jun and c-fos expression, ultimately leading to hypertrophy. In summary, we report here that LacCer specifically induces hypertrophy in cardiomyocytes via an "oxygen-sensitive signal transduction pathway."

The role of the ERK1/2 signalling pathway in the pathogenesis of female stress urinary incontinence

Objective:

To investigate the role of extracellular-regulated protein kinase (ERK)1/2 and phosphorylated (p)-ERK1/2 in the pathogenesis of female stress urinary incontinence (SUI).

Methods:

Anterior vaginal wall tissue was collected from women with SUI and control subjects. Immunohistochemistry and Western blotting were performed for p-ERK1/2. Primary vaginal fibroblast cultures were incubated in the presence or absence of PD98059 (an inhibitor of ERK kinase) and levels of collagen I and III mRNA and protein were examined by quantitative reverse transcription–polymerase chain reaction and Western blot, respectively.

Results:

Levels of p-ERK1/2 were significantly lower in vaginal wall tissue from patients with SUI ( n = 10) compared with controls ( n = 10). PD98059 treatment significantly reduced levels of collagen I and III mRNA and protein.

Conclusions:

Female SUI is associated with reduced levels of p-ERK1/2 compared with controls, and inhibition of the ERK1/2 signalling pathway inhibits collagen type I and III synthesis in vaginal wall fibroblasts.

Urotensin II and the kidney

PURPOSE OF REVIEW

Urotensin II (UTS2), the most potent vasoconstrictor identified thus far, is an undecapeptide hormone with a structure that is highly conserved through mammalian phylogeny. In spite of its broad expression across the invertebrate and vertebrate world, the precise role of UTS2 in physiology and disease is still unknown. The first description of human UTS2 and its receptor brought initial promise of a potential therapeutic target for progressive renal disease, with vasoconstrictive and profibrotic actions within an autocrine and paracrine system and local renal generation that was upregulated with renal pathology.

RECENT FINDINGS

However, the last decade has not brought the successful development of new treatments first hoped for, with one small human clinical trial bearing negative results. What has become apparent is that the spectrum of actions of UTS2 is broad and often paradoxical. This ancient hormone has both vasoconstrictor and vasodilatory actions, has both profibrotic and antiapoptotic activity, as well as actions which are highly contextual on the particular vascular bed studied and on the presence or absence of superimposed disease state.

SUMMARY

With current development of newer UTS2 antagonists attempting to more closely replicate the ligand-receptor kinetics of UTS2 and its receptor, the focus on potential clinical applications of UTS2 inhibition has moved away from the kidney to the treatment of chronic lung and cardiovascular diseases.

Urotensin II-induced collagen synthesis in cultured smooth muscle cells from rat aortic media and a possible involvement of transforming growth factor-β1/Smad2/3 signaling pathway

BACKGROUND

Recent studies suggest that urotensin II (UII) and transforming growth factor-β1 (TGF-β1) both have critical roles in vascular remodeling. UII is a recently discovered vasoconstrictive peptide that is involved in the pathogenesis of atherosclerosis, restenosis and hypertension. TGF-β1 is an important factor that has a pivotal role in vascular fibrosis. This study aimed to explore whether TGF-β1 is involved in UII-induced collagen synthesis in rat aortic vascular smooth muscle cells (VSMCs) and examined the effects and mechanisms of UII on collagen synthesis and secretion in VSMCs.

METHODS

VSMCs were prepared by the explant culture method. TGF-β1 and collagen I secretions from the cells were determined by enzyme-linked immunosorbent assay (ELISA). The mRNA and protein expressions of TGF-β1, collagen I, Smad2 and Smad3 were determined using Real-time RT-PCR and Western blotting.

RESULTS

UII dose-dependently promoted TGF-β1 protein expression and secretion from VSMCs, with maximal effect at 10(-8) mol/l at 24 h for protein expression and 10(-7) mol/l at 24 h for protein secretion (both P<0.01). Moreover, UII dose-dependently promoted Smad2 and Smad3 mRNA expression in VSMCs, with maximal effect at 10(-8) mol/l for 12 h (both P<0.01). The effects of UII were significantly inhibited by its receptor antagonists urantide (10(-6) mol/l) or SB-710411 (10(-6) mol/l), and by the mitogen-activated protein kinase (MAPK/ERK) inhibitor PD98059 (10(-6) mol/l). UII dose-dependently promoted collagen I mRNA expression and protein secretion in VSMCs, with maximal effect at 10(-8) mol/l at 12h for mRNA expression and 10(-6) mol/l at 24 h for protein secretion (both P<0.01). Collagen synthesis and secretion from VSMCs induced by UII were inhibited significantly by a TGF-β1-specific neutralizing antibody, SB-431542 (an antagonist of the TGF-β1 type II receptor) and PD98059 (all P<0.01).

CONCLUSIONS

This study suggests that UII could induce collagen synthesis and secretion through upregulation of TGF-β1 expression and secretion in VSMCs, and that TGF-β1/Smad2/3 signaling might be one of the important pathways by which UII is involved in vascular fibrosis.