Inhibition of SMAD2 phosphorylation preserves cardiac function during pressure overload.
Bjørnstad Johannes L,Skrbic Biljana,Marstein Henriette S,Hasic Almira,Sjaastad Ivar,Louch William E,Florholmen Geir,Christensen Geir,Tønnessen Theis
Cardiovascular research
AIMS:Left ventricular (LV) pressure overload leads to myocardial remodelling and reduced cardiac function. Both cardioprotective and deleterious effects have been attributed to SMAD2/3 (SMAD, small mothers against decapentaplegic) signalling, but the role of these important molecules in pressure overload remains unclear. The aim of this study was to examine the effects of SMAD2 inhibition on cardiac function and remodelling in mice subjected to aortic banding (AB), using a small molecule inhibitor (SM16) of SMAD2 signalling. METHODS AND RESULTS:C57BL/6 mice were subjected to 1 week of AB, which led to a three-fold increased phosphorylation of SMAD2 that was reduced by SM16 (P≤ 0.05), as measured by western blotting. Cardiac function was evaluated by echocardiography and was preserved by SM16, as fractional shortening was increased by 38% (P≤ 0.05) and mitral flow deceleration reduced by 28% compared with AB mice not receiving SM16 (P≤ 0.05). In accordance with this, SM16 abolished the 21% increase in lung weight in AB mice (P≤ 0.05). Cardiomyocyte hypertrophy and foetal gene expression, as measured by qPCR, were also reduced. Myocardial collagen protein was unaltered 1 week after AB. LV sarcoplasmic reticulum Ca(2+)ATPase (SERCA2) reduction in AB mice and in transforming growth factor-β1-stimulated rat cardiomyocytes was diminished by SM16. Ca(2+) transient decay kinetics were improved in cardiomyocytes isolated from AB mice receiving SM16. CONCLUSION:In pressure overload, pharmacological inhibition of SMAD2 signalling attenuated cardiomyocyte hypertrophy and preserved cardiac function. SM16 prevented SMAD2-mediated downregulation of SERCA2 in vivo and in cardiomyocytes, suggesting improved cardiomyocyte Ca(2+) handling as a possible cardioprotective mechanism.
10.1093/cvr/cvr294
Attenuation of diabetic cardiomyopathy by relying on kirenol to suppress inflammation in a diabetic rat model.
Wu Bin,Huang Xue-Yuan,Li Le,Fan Xiao-Hang,Li Peng-Cheng,Huang Chuan-Qi,Xiao Juan,Gui Rong,Wang Shun
Journal of cellular and molecular medicine
Diabetic cardiomyopathy is characterized by diabetes-induced myocardial abnormalities, accompanied by inflammatory response and alterations in inflammation-related signalling pathways. Kirenol, isolated from Herba Siegesbeckiae, has potent anti-inflammatory properties. In this study, we aimed to investigate the cardioprotective effect of kirenol against DCM and underlying the potential mechanisms in a type 2 diabetes mellitus model. Kirenol treatment significantly decreased high glucose-induced cardiofibroblasts proliferation and increased the cardiomyocytes viability, prevented the loss of mitochondrial membrane potential and further attenuated cardiomyocytes apoptosis, accompanied by a reduction in apoptosis-related protein expression. Kirenol gavage could affect the expression of pro-inflammatory cytokines in a dose-dependent manner but not lower lipid profiles, and only decrease fasting plasma glucose, fasting plasma insulin and mean HbA1c levels in high-dose kirenol-treated group at some time-points. Left ventricular dysfunction, hypertrophy, fibrosis and cell apoptosis, as structural and functional abnormalities, were ameliorated by kirenol administration. Moreover, in diabetic hearts, oral kirenol significantly attenuated activation of mitogen-activated protein kinase subfamily and nuclear translocation of NF-κB and Smad2/3 and decreased phosphorylation of IκBα and both fibrosis-related and apoptosis-related proteins. In an Electrophoretic mobility shift assay, the binding activities of NF-κB, Smad3/4, SP1 and AP-1 in the nucleus of diabetic myocardium were significantly down-regulated by kirenol treatment. Additionally, high dose significantly enhanced myocardial Akt phosphorylation without intraperitoneal injection of insulin. Kirenol may have potent cardioprotective effects on treating for the established diabetic cardiomyopathy, which involves the inhibition of inflammation and fibrosis-related signalling pathways and is independent of lowering hyperglycaemia, hyperinsulinemia and lipid profiles.
10.1111/jcmm.14638
Activin receptor-like kinase 7 mediates high glucose-induced H9c2 cardiomyoblast apoptosis through activation of Smad2/3.
Liu Lin,Ding Wen-yuan,Zhao Jing,Wang Zhi-hao,Zhong Ming,Zhang Wei,Chen Yu-guo,Zhang Yun,Li Li,Tang Meng-xiong
The international journal of biochemistry & cell biology
Cardiomyocyte apoptosis is an important pathological change of diabetic cardiomyopathy. How the elevated glucose levels cause cell apoptosis remains unknown. The aim of our study was to investigate whether activin receptor-like kinase 7 (ALK7)-Smad2/3 signaling pathway plays an important role in high glucose-induced cardiomyocyte apoptosis. H9c2 cardiomyoblasts and neonatal rat cardiomyocytes were treated with 33mmol/l glucose. The expression of ALK7, Smad2 and Smad3 were inhibited by small interfering RNA respectively. The level of ALK7, total Smad2/3, phosphorylated Smad2/3, B-cell lymphoma-2 (Bcl-2) and cleaved Caspase3 were evaluated using western blot. The apoptosis rate was detected by flow cytometer. High glucose treatment caused the apoptosis of H9c2 cardiomyocyte and the inhibition of Smad2 or Smad3 attenuated this apoptosis. ALK7 existed in both H9c2 cardiomyoblasts and neonatal rat cardiomyocytes and high ambient glucose upregulated its expression. The increased expression level of cleaved Caspase3 and apoptosis rate and decreased expression of Bcl-2 were reversed after ALK7 was inhibited. The expression of phosphorylated Smad2/3 also decreased after the knockdown of ALK7. Our findings suggest that ALK7 mediates high ambient glucose-induced H9c2 cardiomyoblasts apoptosis through the activation of Smad2/3.
10.1016/j.biocel.2013.06.018
Angiotensin II-induced cardiomyocyte hypertrophy in vitro is TAK1-dependent and Smad2/3-independent.
Watkins Sarah J,Borthwick Gillian M,Oakenfull Rachael,Robson Andrew,Arthur Helen M
Hypertension research : official journal of the Japanese Society of Hypertension
Cardiac hypertrophy occurs as an adaptation to hypertension but a sustained hypertrophic response can ultimately lead to heart failure. Angiotensin-II (Ang II) is released following hemodynamic overload and stimulates a cardiac hypertrophic response. AngII also increases expression of the regulatory cytokine, transforming growth factor-β1 (TGFβ1), which is also implicated in the cardiac hypertrophic response and can stimulate activation of Smad2/3 as well as TGFβ-activated kinase 1 (TAK1) signaling mediators. To better understand the downstream signaling events in cardiac hypertrophy, we therefore investigated activation of Smad2/3 and TAK1 signaling pathways in response to Ang II and TGFβ1 using primary neonatal rat cardiomyocytes to model cardiac hypertrophic responses. Small interfering RNA (siRNA) knockdown of Smad 2/3 or TAK1 protein or addition of the TGFβ type I receptor inhibitor, SB431542, were used to investigate the role of downstream mediators of TGFβ signaling in the hypertrophic response. Our data revealed that TGFβ1 stimulation leads to cardiomyocyte hypertrophic phenotypes that were indistinguishable from those occurring in response to Ang II. In addition, inhibition of the TGFβ1 type receptor abolished Ang II-induced hypertrophic changes. Furthermore, the hypertrophic response was also prevented following siRNA knockdown of TAK1 protein, but was unaffected by knockdown of Smad2/3 proteins. We conclude that Ang II-induced cardiomyocyte hypertrophy in vitro occurs in a TAK1-dependent, but Smad-independent, manner.
10.1038/hr.2011.196
Salvianolate inhibits reactive oxygen species production in H(2)O(2)-treated mouse cardiomyocytes in vitro via the TGFβ pathway.
Fei Ai-hua,Cao Qing,Chen Shu-yan,Wang Hai-rong,Wang Fei-long,Pan Shu-ming,Lin Zhao-fen
Acta pharmacologica Sinica
AIM:To investigate the effects of salvianolate, a water-soluble active compound from Salvia miltiorrhiza Bunge, on reactive oxygen species (ROS) production in mouse cardiomyocytes in vitro. METHODS:Primary ventricular cardiomyocytes were prepared from neonatal mouse. The cell viability was determined using MTT assay. Culture medium for each treatment was collected for measuring the levels of NO, iNOS, total antioxidant capacity (TAOC) and transforming growth factor β1 (TGFβ1). TGFβ1 and Smad2/3 expression in the cells was detected with Western blotting. RESULTS:H2O2 (1.25 mmol/L) did not significantly affect the cell viability, whereas the high concentration of salvianolate (5 g/L) alone dramatically suppressed the cell viability. Treatment of the cells with H2O2 (1.25 mmol/L) markedly increased ROS and iNOS production, and decreased the levels of NO, TAOC and TGFβ1 in the culture medium. Furthermore, the H2O2 treatment significantly increased TGFβ1 and Smad2/3 expression in the cells. Addition of salvianolate (0.05, 0.1, and 0.5 g/L) concentration-dependently reversed the H2O2-induced alterations in the culture medium; addition of salvianolate (0.05 g/L) reversed the H2O2-induced increases of TGFβ1 and Smad2/3 expression in the cells. Blockage of TGFβ1 with its antibody (1 mg/L) abolished the above mentioned effects of salvianolate. CONCLUSION:Salvianolate inhibits ROS and iNOS production and increases TAOC and NO levels in H2O2-treated cardiomyocytes in vitro via downregulation of Smad2/3 and TGFβ1 expression. High concentration of salvianolate causes cytotoxicity in mouse cardiomyocytes.
10.1038/aps.2012.209
C1q/TNF-Related Protein 9 Inhibits Coxsackievirus B3-Induced Injury in Cardiomyocytes through NF-B and TGF-1/Smad2/3 by Modulating THBS1.
Mediators of inflammation
C1q/TNF-related protein 9 (CTRP9) is implicated in diverse cardiovascular diseases, but its role in viral myocarditis (VMC) is not well explored. This study is aimed at investigating the role and potential mechanism of CTRP9 in VMC. Herein, we found that the peripheral blood collected from children with VMC had lower CTRP9 levels than that from children who had recovered from VMC. H9c2 cardiomyocytes treated with coxsackievirus B3 (CVB3) were applied to establish a VMC model , and the expression of CTRP9 was significantly decreased in CVB3-induced H9c2 cells. The overexpression of CTRP9 attenuated CVB3-induced apoptosis, inflammation, and fibrosis reactions in H9c2 cells by promoting cell proliferation, reducing the cell apoptosis rate, and inhibiting inflammatory cytokine levels and fibrosis-related gene expression. Moreover, we found that thrombospondin 1 (THBS1) levels were increased in children with VMC, and CTRP9 negatively regulated THBS1 expression by interacting with THBS1. The downregulation of THBS1 inhibited CVB3-induced apoptosis, inflammation, and fibrosis in H9c2 cells. In addition, our mechanistic investigation indicated that the overexpression of THBS1 impaired the inhibitory effect of CTRP9 on CVB3-induced H9c2 cells. The results further revealed that the CVB3-induced NF-B and TGF-1/Smad2/3 signaling pathways of H9c2 cells were blocked by CTRP9 yet activated by THBS1. In conclusion, CTRP9 protected H9c2 cells from CVB3-induced injury via the NF-B and TGF-1/Smad2/3 signaling pathways by modulating THBS1.
10.1155/2020/2540687
GDF11 Modulates Ca-Dependent Smad2/3 Signaling to Prevent Cardiomyocyte Hypertrophy.
Duran Javier,Troncoso Mayarling Francisca,Lagos Daniel,Ramos Sebastian,Marin Gabriel,Estrada Manuel
International journal of molecular sciences
Growth differentiation factor 11 (GDF11), a member of the transforming growth factor-β family, has been shown to act as a negative regulator in cardiac hypertrophy. Ca signaling modulates cardiomyocyte growth; however, the role of Ca-dependent mechanisms in mediating the effects of GDF11 remains elusive. Here, we found that GDF11 induced intracellular Ca increases in neonatal rat cardiomyocytes and that this response was blocked by chelating the intracellular Ca with BAPTA-AM or by pretreatment with inhibitors of the inositol 1,4,5-trisphosphate (IP₃) pathway. Moreover, GDF11 increased the phosphorylation levels and luciferase activity of Smad2/3 in a concentration-dependent manner, and the inhibition of IP₃-dependent Ca release abolished GDF11-induced Smad2/3 activity. To assess whether GDF11 exerted antihypertrophic effects by modulating Ca signaling, cardiomyocytes were exposed to hypertrophic agents (100 nM testosterone or 50 μM phenylephrine) for 24 h. Both treatments increased cardiomyocyte size and [³H]-leucine incorporation, and these responses were significantly blunted by pretreatment with GDF11 over 24 h. Moreover, downregulation of Smad2 and Smad3 with siRNA was accompanied by inhibition of the antihypertrophic effects of GDF11. These results suggest that GDF11 modulates Ca signaling and the Smad2/3 pathway to prevent cardiomyocyte hypertrophy.
10.3390/ijms19051508