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Hypertensive cardiac remodeling is a major cause of heart failure. The immunoproteasome is an inducible form of the proteasome and its catalytic subunit β5i (also named LMP7) is involved in angiotensin II-induced atrial fibrillation; however, its role in deoxycorticosterone-acetate (DOCA)-salt-induced cardiac remodeling remains unclear. C57BL/6 J wild-type (WT) and β5i knockout (β5i KO) mice were subjected to uninephrectomy (sham) and DOCA-salt treatment for three weeks. Cardiac function, fibrosis, and inflammation were evaluated by echocardiography and histological analysis. Protein and gene expression levels were analyzed by quantitative real-time PCR and immunoblotting. Our results showed that after 21 days of DOCA-salt treatment, β5i expression and chymotrypsin-like activity were the most significantly increased factors in the heart compared with the sham control. Moreover, DOCA-salt-induced elevation of blood pressure, adverse cardiac function, chamber and myocyte hypertrophy, interstitial fibrosis, oxidative stress, and inflammation were markedly attenuated in β5i KO mice. These findings were verified in β5i inhibitor PR-957-treated mice. Moreover, blocking of PTEN (the gene of phosphate and tensin homolog deleted on chromosome ten) markedly attenuated the inhibitory effect of β5i knockout on DOCA-salt-induced cardiac remodeling. Mechanistically, DOCA-salt stress upregulated the expression of β5i, which promoted the degradation of PTEN and the activation of downstream signals (AKT/mTOR, TGF-β1/Smad2/3, NOX, and NF-κB), which ultimately led to cardiac hypertrophic remodeling. This study provides new evidence of the critical role of β5i in DOCA-salt-induced cardiac remodeling through the regulation of PTEN stability, and indicates that the inhibition of β5i may be a promising therapeutic target for the treatment of hypertensive heart diseases.

Background Recent studies have reported the prevalence of cardiovascular diseases (CVDs) among cancer patients following the use of the vascular endothelial growth factor (VEGF) signaling inhibitors. However, data for patients with a history of cancer before active cancer treatment are lacking. This study aims to investigate the distribution of CVD-related comorbidities before cancer treatment in potential VEGF antagonists candidates. Methods A total of 22 500 newly diagnosed cancer patients registered from 1 January 2011 to 31 December 2017 were included. Cancer patients with colorectal cancer (CRC), renal cell carcinoma (RCC), thyroid cancer, hepatocellular carcinoma (HCC), and lung cancer were selected. Results Hypertension (HTN), coronary heart diseases, atrial fibrillation, and heart failure were top CVD comorbidities among studied cancers. HTN was the most prevalent CVD (26.0%). The prevalence of HTN in RCC, CRC (33.5 and 29.4% respectively) was significantly higher than that in HCC, lung cancer, and thyroid cancer patients (25.1, 24.5, and 23.1%, respectively). Among cancer patients with HTN, the majority of cancer patients fall in grade III (75.7%) and very high cardiovascular risk level (85.4%). Out of the 5847 HTN patients, 26% were not in antihypertensive use, and 34.2% failed to achieve the target blood pressure. Conclusion Cancer patients carry a high burden of CVD-related comorbidities before the application of VEGF antagonists. HTN is the most prevalent comorbid condition, and cancer patients with HTN constitute substantial cardiovascular risks and a higher co-prevalence of other CVDs.

Excess myocardial triacylglycerol accumulation (i.e., cardiac steatosis) impairs heart function, suggesting that enzymes promoting triacylglycerol metabolism exert essential regulatory effects on heart function. Comparative gene identification 58 (CGI-58) is a key enzyme that promotes the hydrolysis of triglycerides by activating adipose triglyceride lipase and plays a protective role in maintaining heart function. In this study, the effects of CGI-58 on heart function and the underlying mechanism were investigated using cardiac-specific CGI58-knockout mice (CGI-58cko mice). Echocardiography and pathological staining were performed to detect changes in the structure and function of the heart. Proteomic profiling, immunofluorescent staining, western blotting, and real-time PCR were used to evaluate molecular changes. In CGI-58cko mice, we detected cardiac hypertrophic remodeling and heart failure associated with excessive cardiac lipid accumulation, ROS production, and decreased expression of regulators of fatty acid metabolism. These changes were markedly attenuated in CGI-58cko mice injected with rAAV9-CGI58. A quantitative proteomics analysis revealed significant increases in the expression of ER stress-related proteins and decreases in proteins related to fatty acid and amino acid metabolism in the hearts of CGI-58cko mice. Furthermore, the inhibition of ER stress by the inhibitor 4-PBA improved mitochondrial dysfunction, reduced oxidative stress, and reversed cardiac remodeling and dysfunction in cultured cardiomyocytes or in CGI-58cko mice. Our results suggested that CGI-58 is essential for the maintenance of heart function by reducing lipid accumulation and ER stress in cardiomyocytes, providing a new therapeutic target for cardiac steatosis and dysfunction.

Sustained cardiac hypertrophy is a major cause of heart failure (HF) and death. Recent studies have demonstrated that resveratrol (RES) exerts a protective role in hypertrophic diseases. However, the molecular mechanisms involved are not fully elucidated. In this study, cardiac hypertrophic remodeling in mice were established by pressure overload induced by transverse aortic constriction (TAC). Cardiac function was evaluated by echocardiography and invasive pressure-volume analysis. Cardiomyocyte size was detected by wheat germ agglutinin staining. The protein and gene expressions of signaling mediators and hypertrophic markers were examined. Our results showed that administration of RES significantly suppressed pressure overload-induced cardiac hypertrophy, fibrosis and apoptosis and improved in vivo heart function in mice. RES also reversed pre-established hypertrophy and restoring contractile dysfunction induced by chronic pressure overload. Moreover, RES treatment blocked TAC-induced increase of immunoproteasome activity and catalytic subunit expression (β1i, β2i and β5i), which inhibited PTEN degradation thereby leading to inactivation of AKT/mTOR and activation of AMPK signals. Further, blocking PTEN by the specific inhibitor VO-Ohpic significantly attenuated RES inhibitory effect on cardiomyocyte hypertrophy in vivo and in vitro. Taken together, our data suggest that RES is a novel inhibitor of immunoproteasome activity, and may represent a promising therapeutic agent for the treatment of hypertrophic diseases., Highlights • Resveratrol (RES) protects from pressure overload-induced cardiac hypertrophic remodeling. • RES can inhibit immunosubunit expression and activity in cardiomyocytes. • RES increases PTEN stability leading to inhibition of AKT/mTOR and activation of AMPK. • Blocking PTEN significantly attenuates RES-mediated beneficial effect on cardiomyocyte hypertrophy.

Pressure overload-induced hypertrophic remodeling is a critical pathological process leading to heart failure (HF). Suppressor of cytokine signaling-3 (SOCS3) has been demonstrated to protect against cardiac hypertrophy and dysfunction, but its mechanisms are largely unknown. Using primary cardiomyocytes and cardiac-specific SOCS3 knockout (SOCS3cko) or overexpression mice, we demonstrated that modulation of SOCS3 level influenced cardiomyocyte hypertrophy, apoptosis and cardiac dysfunction induced by hypertrophic stimuli. We found that glucose regulatory protein 78 (GRP78) was a direct target of SOCS3, and that overexpression of SOCS3 inhibited cardiomyocyte hypertrophy and apoptosis through promoting proteasomal degradation of GRP78, thereby inhibiting activation of endoplasmic reticulum (ER) stress and mitophagy in the heart. Thus, our results uncover SOCS3-GRP78-mediated ER stress as a novel mechanism in the transition from cardiac hypertrophy to HF induced by sustained pressure overload, and suggest that modulating this pathway may provide a new therapeutic approach for hypertrophic heart diseases.

Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia and is a major cause of stroke and heart failure. We and others have found that gallic acid (GA) plays a beneficial role in cardiac hypertrophic remodeling and hypertension. However, the effect of GA on angiotensin II (Ang II)-induced AF and atrial remodeling as well as the underlying mechanisms remain unknown. AF was induced in mice by Ang II infusion (2000 ng/kg/min) for 3 weeks. Blood pressure was measured using the tail-cuff method. Atrial volume was evaluated by echocardiography. Atrial remodeling was studied using hematoxylin and eosin, Masson’s trichrome, and immunohistochemical staining. Atrial oxidative stress was assessed by dihydroethidium staining. The gene expression of fibrotic and inflammatory markers and protein levels of signaling mediators were measured by quantitative real-time PCR and western blot analysis. In mice, GA administration significantly attenuated Ang II-induced elevation of blood pressure, AF incidence and duration, atrial dilation, fibrosis, inflammation, and oxidative stress compared with the vehicle control. Furthermore, GA downregulated Ang II-induced activity and expression of immunoproteasome subunits (β2i and β5i), which reduced PTEN degradation and led to the inactivation of AKT1 and downstream signaling mediators. Importantly, blocking PTEN activity by VO-Ohpic markedly reversed the GA-mediated protective effects on Ang II-induced AF and atrial remodeling. Therefore, our results provide novel evidence that GA exerts a cardioprotective role by inhibiting immunoproteasome activity, which attenuates PTEN degradation and activation of downstream signaling, and may represent a promising candidate for treating hypertensive AF.

UCHL1 positively regulates cardiac hypertrophy via stabilizing EGFR and highlighting it as a yet unknown therapeutic target., Pathological cardiac hypertrophy leads to heart failure (HF). The ubiquitin-proteasome system (UPS) plays a key role in maintaining protein homeostasis and cardiac function. However, research on the role of deubiquitinating enzymes (DUBs) in cardiac function is limited. Here, we observed that the deubiquitinase ubiquitin C-terminal hydrolase 1 (UCHL1) was significantly up-regulated in agonist-stimulated primary cardiomyocytes and in hypertrophic and failing hearts. Knockdown of UCHL1 in cardiomyocytes and mouse hearts significantly ameliorated cardiac hypertrophy induced by agonist or pressure overload. Conversely, overexpression of UCHL1 had the opposite effect in cardiomyocytes and rAAV9-UCHL1–treated mice. Mechanistically, UCHL1 bound, deubiquitinated, and stabilized epidermal growth factor receptor (EGFR) and activated its downstream mediators. Systemic administration of the UCHL1 inhibitor LDN-57444 significantly reversed cardiac hypertrophy and remodeling. These findings suggest that UCHL1 positively regulates cardiac hypertrophy by stabilizing EGFR and identify UCHL1 as a target for hypertrophic therapy.

Background/Aim: Hypertensive cardiac hypertrophy is the leading cause of cardiac remodeling and heart failure. We recently demonstrated that the immunoproteasome, an inducible form of the constitutive proteasome, plays a critical role in regulating cardiovascular diseases. However, the role of the immunoproteasome LMP10 (β2i) catalytic subunit in the regulation of angiotensin II (Ang II)-induced cardiac hypertrophic remodeling remains unclear. Methods: Wild-type (WT) and LMP10 knockout (KO) mice were infused with Ang II 1000 ng/kg/min for 2 weeks. Blood pressure was measured using a tail-cuff system. Cardiac function and hypertrophic remodeling were examined by echocardiography and histological staining. The expression levels of genes and proteins were examined with quantitative real-time PCR and immunoblotting analysis, respectively. Results: LMP10 mRNA and protein expression was significantly increased in Ang II-stimulated hearts and primary cardiomyocytes. Moreover, Ang II infusion for 2 weeks increased systolic blood pressure, abnormal cardiac function, hypertrophy, fibrosis, and inflammation in WT mice, which were significantly reversed in KO mice. Moreover, a marked reduction in the protein levels of insulin growth factor-1 receptor (IGF1R), glycoprotein 130 (gp130) and phosphorylated AKT, mTOR, STAT3 and ERK1/2 and an increase in the LC3II/I ratio were also observed in LMP10 KO mice compared with WT mice after Ang II infusion. In vitro culture experiments confirmed that LMP10 knockdown activated autophagy and increased IGF1R and gp130 degradation, leading to the inhibition of cardiomyocyte hypertrophy. However, inhibiting autophagy with chloroquine reversed this effect. Conclusion: The results of this study indicate that LMP10 KO attenuates Ang II-induced cardiac hypertrophic remodeling via the autophagy-dependent degradation of IGF1R and gp130, and suggests that LMP10 may be a novel therapeutic target for hypertrophic heart diseases.

Intercellular adhesion molecule-1 (ICAM-1) is a member of an immunoglobulin-like superfamily of adhesion molecules that mediate leukocyte adhesion to vascular endothelium and are involved in several cardiovascular diseases, including ischemia-reperfusion injury, myocardial infarction, and atherosclerosis. However, the role of ICAM-1 in angiotensin II (ANG II)-induced cardiac remodeling in mice remains unclear. Wild-type mice were administered an IgG control or ICAM-1 neutralizing antibody (1 and 2 mg/mouse, respectively) and ANG II (1,000 ng·kg−1·min−1) for up to 14 days. Cardiac contractile function and structure were detected by echocardiography. Hypertrophy, fibrosis, and inflammation were assessed by histological examination. The infiltration of lymphocyte function-associated antigen-1 (LFA-1+) monocytes/macrophages was assessed by immunostaining. The mRNA expression of genes was evaluated by quantitative RT-PCR analysis. Protein levels were tested by immunoblotting. We found that ICAM-1 expression in ANG II-infused hearts and ICAM-1 levels in serum from human patients with heart failure were significantly increased. Moreover, ANG II infusion markedly enhanced ANG II-induced hypertension, caused cardiac contractile dysfunction, and promoted cardiac hypertrophy, fibrosis, and LFA-1+ macrophage infiltration. Conversely, blockage of ICAM-1 with a neutralizing antibody dose-dependently attenuated these effects. Moreover, our in vitro data further demonstrated that blocking ICAM-1 inhibited ANG II-induced LFA-1+ macrophage adhesion to endothelial cells and migration. In conclusion, these results provide novel evidence that blocking ICAM-1 exerts a protective effect in ANG II-induced cardiac remodeling at least in part through the modulation of adhesion and infiltration of LFA-1+ macrophages in the heart. Inhibition of ICAM-1 may represent a new therapeutic approach for hypertrophic heart diseases. NEW & NOTEWORTHY Leukocyte adhesion to vascular endothelium is a critical step in cardiovascular diseases. ICAM-1 is a member of immunoglobulin-like superfamily of adhesion molecules that binds LFA-1 to mediate leukocytes adhesion and migration. However, the significance of ICAM-1 in ANG II-induced cardiac remodeling remains unclear. This study reveals that blocking of ICAM-1 prevents ANG II-induced cardiac remodeling via modulating adhesion and migration of LFA-1+ monocytes, may serve as a novel therapeutic target for hypertensive cardiac diseases.

Cardiac remodeling is an important pathological process ultimately leading to heart failure. Ubiquitin carboxy-terminal hydrolase 1 (UCHL1) is a deubiquitinase that plays a critical role in neurodegenerative diseases and cancer. However, its role in cardiac remodeling in spontaneously hypertensive rats remains unclear. Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) were administered the UCHL1 inhibitor LDN-57444 (20 μg/kg/day) from 2 months of age for 4 months. Blood pressure, cardiac hypertrophy, fibrosis, inflammation, and oxidative stress were evaluated by the tail-cuff system, echocardiography, and histological analysis. Gene and protein expression levels were examined by real-time PCR and immunoblotting analysis. At 6 months of age, the expression of UCHL at the mRNA and protein levels was significantly upregulated in SHRs compared with WKYs. Moreover, systolic blood pressure, cardiac performance, left ventricular (LV) hypertrophy, fibrosis, inflammation, and superoxide production were significantly increased in SHRs compared with WKYs, and these effects were markedly attenuated by LDN-57444 after 4 months of administration. These beneficial actions were possibly associated with a reduction in blood pressure and inactivation of multiple signaling pathways, including AKT, ERK1/2, STAT3, calcineurin A, TGF-β/Smad2/3, and NF-κB. In conclusion, the results indicate that UCHL1 is involved in hypertensive cardiac remodeling in SHRs, and targeting UCHL1 activity may be a novel potential therapeutic approach for the treatment of hypertensive heart diseases.

Vitamin D (VD) and its analogues play critical roles in metabolic and cardiovascular diseases. Recent studies have demonstrated that VD exerts a protective role in cardiovascular diseases. However, the beneficial effect of VD on pressure overload-induced cardiac remodeling and dysfunction and its underlying mechanisms are not fully elucidated. In this study, cardiac dysfunction and hypertrophic remodeling in mice were induced by pressure overload. Cardiac function was evaluated by echocardiography, and myocardial histology was detected by H&E and Masson's trichrome staining. Cardiomyocyte size was detected by wheat germ agglutinin staining. The protein levels of signaling mediators were examined by western blotting while mRNA expression of hypertrophic and fibrotic markers was examined by qPCR analysis. Oxidative stress was detected by dihydroethidine staining. Our results showed that administration of VD3 significantly ameliorates pressure overload-induced contractile dysfunction, cardiac hypertrophy, fibrosis and inflammation in mice. In addition, VD3 treatment also markedly inhibited cardiac oxidative stress and apoptosis. Moreover, protein levels of calcineurin A, ERK1/2, AKT, TGF-β, GRP78, cATF6, and CHOP were significantly reduced whereas SERCA2 level was upregulated in the VD3-treated hearts compared with control. These results suggest that VD3 attenuates cardiac remodeling and dysfunction induced by pressure overload, and this protective effect is associated with inhibition of multiple signaling pathways.

Background/Aims: Cardiac remodeling is a critical pathogenetic process leading to heart failure. Suppressor of cytokine signaling-3 (SOCS3) is demonstrated as a key negative regulator of the gp130 receptor to inhibit cardiac hypertrophy. However, the role of SOCS3 in deoxycorticosterone-acetate (DOCA)-salt-induced cardiac remodeling remains unclear. Methods: Cardiac-specific SOCS3 knockout (SOCS3cKO) and wild-type (WT) C57BL/6J mice were subjected to uninephrectomy and DOCA-salt for 3 weeks. The effect of SOCS3 on cardiac remodeling and inflammation was evaluated by histological analysis. Gene and protein levels were measured by real-time PCR and immunoblotting analysis. Results: After DOCA-salt treatment, the expression of SOCS3, activation of gp130/JAK/STAT3, cardiac dysfunction and fibrosis in DOCA-salt mice were significantly elevated, which were markedly attenuated by eplerenone, a specific mineralocorticoid receptor (MR) blocker. Moreover, DOCA-salt-induced cardiac dysfunction, hypertrophy, fibrosis and inflammation were aggravated in SOCS3cKO mice, but were significantly reduced in AAV9-SOCS3-injected mice. These effects were mostly associated with activation of gp130/STAT3/AKT/ERK1/2, TGF-β/Smad2/3 and NF-κB signaling pathways. Conclusions: Our data demonstrate that loss of SOCS3 in cardiomyocytes promotes DOCA-salt-induced cardiac remodeling and inflammation, and it may be a novel potential therapeutic target for hypertensive heart disease.

B lymphocytes have been shown to contribute to autoimmune diseases via producing antibodies and proinflammatory cytokines. Depletion of B cells by blocking CD20 can inhibit these diseases. Here we examined whether an antibody against CD20, rituximab (RTX) (Rituxan@), used clinically in oncology could have similar anti-inflammatory effects in cardiac remodeling and heart failure (HF) in mice. Cardiac remodeling was established by pressure overload induced by transverse aortic constriction (TAC). Wild-type (WT) male C57BL/6 J mice were subjected to pressure overload by using transverse aortic constriction and then received RTX for 4 weeks. Administration of RTX markedly improves in vivo heart function, and suppressed heart chamber dilation, myocyte hypertrophy, fibrosis and oxidative stress in mice after TAC operation. RTX treatment also reversed established hypertrophic remodeling induced by TAC. Moreover, TAC-induced activation of multiple signaling pathways including calcineurin A, ERK1/2, STAT3, TGFβ/Smad2/3 and IKKα/β/NF-kB were remarkably attenuated in RTX-treated hearts compared with controls. These inhibitory effects of RTX were associated with inhibition of proinflammatory cytokine expression and Th2 cytokine-mediated IgG production from B cells. In conclusion, this study identifies that administration of RTX can inhibit pressure overload-induced cardiac remodeling and dysfunction in mice, and suggest that RTX may be a promising drug for treating hypertrophic disease.

Immunoproteasome subunit β5i regulates cardiac hypertrophy., Pathological cardiac hypertrophy eventually leads to heart failure without adequate treatment. The immunoproteasome is an inducible form of the proteasome that is intimately involved in inflammatory diseases. Here, we found that the expression and activity of immunoproteasome catalytic subunit β5i were significantly up-regulated in angiotensin II (Ang II)–treated cardiomyocytes and in the hypertrophic hearts. Knockout of β5i in cardiomyocytes and mice markedly attenuated the hypertrophic response, and this effect was aggravated by β5i overexpression in cardiomyocytes and transgenic mice. Mechanistically, β5i interacted with and promoted ATG5 degradation thereby leading to inhibition of autophagy and cardiac hypertrophy. Further, knockdown of ATG5 or inhibition of autophagy reversed the β5i knockout-mediated reduction of cardiomyocyte hypertrophy induced by Ang II or pressure overload. Together, this study identifies a novel role for β5i in the regulation of cardiac hypertrophy. The inhibition of β5i activity may provide a new therapeutic approach for hypertrophic diseases.

Scope Gallic acid (GA) is a dietary phenolic acid found in tea, red wine, and some plants. It exhibits anti-oxidative and anti-inflammatory activities. Recent studies have revealed that GA has beneficial effects against several cardiovascular diseases; however, whether GA attenuates pressure-overload-induced cardiac hypertrophy and the underlying mechanism remains unclear. Methods and results Primary cardiomyocyte hypertrophy is stimulated with angiotensin II (Ang II). Cardiac hypertrophic remodeling is induced in mice by transverse aortic constriction (TAC). Myocardial function is evaluated by echocardiographic and hemodynamic analyses, while cardiac tissues are analyzed by histological staining. It is observed that GA significantly decreases Ang II-induced increases in cardiomyocyte size in vitro. Administration of GA in mice markedly improves TAC-induced cardiac dysfunction and attenuates pathological changes, including cardiac myocyte hypertrophy, fibrosis, inflammation, and oxidative stress. Mechanistically, GA inhibits ULK1 and activates autophagy, which induces the degradation of EGFR, gp130, and calcineurin A, thereby inhibiting the downstream signaling cascades (AKT, ERK1/2, JAK2/STAT3, and NFATc1). Conclusions The results demonstrate for the first time that GA prevents myocardial hypertrophy and dysfunction via an autophagy-dependent mechanism. Thus, GA represents a promising therapeutic candidate for treating cardiac hypertrophy and heart failure.

System hypertension is a major risk factor for cardiac hypertrophy and heart failure. Our recent findings reveal that the ablation or inhibition of C-X-C chemokine receptor (CXCR) 2 blocks this process in mice; however, it is not clear whether the pharmacological inhibition of CXCR2 attenuates hypertension and subsequent cardiac remodeling in spontaneously hypertensive rats (SHRs). In the present study, we showed that chemokines (CXCL1 and CXCL2) and CXCR2 were significantly upregulated in SHR hearts compared with Wistar–Kyoto rat (WKY) hearts. Moreover, the administration of CXCR2-specific inhibitor N-(2-hydroxy-4-nitrophenyl)-N′-(2-bromophenyl)-urea (SB225002) in SHRs (at 2 months of age) for an additional 4 months significantly suppressed the elevation of blood pressure, cardiac myocyte hypertrophy, fibrosis, inflammation, and superoxide production and improved heart dysfunction in SHRs compared with vehicle-treated SHRs. SB225002 treatment also reduced established hypertension, cardiac remodeling and contractile dysfunction. Moreover, CXCR2-mediated increases in the recruitment of Mac-2-positive macrophages, proinflammatory cytokines, vascular permeability and ROS production in SHR hearts were markedly attenuated by SB225002. Accordingly, the inhibition of CXCR2 by SB225002 deactivates multiple signaling pathways (AKT/mTOR, ERK1/2, STAT3, calcineurin A, TGF-β/Smad2/3, NF-κB-p65, and NOX). Our results provide new evidence that the chronic blocking of CXCR2 activation attenuates progression of cardiac hypertrophic remodeling and dysfunction in SHRs. These findings may be of value in understanding the benefits of CXCR2 inhibition for hypertensive cardiac hypertrophy and provide further support for the clinical application of CXCR2 inhibitors for the prevention and treatment of heart failure.

Rationale: Sustained cardiac hypertrophy often leads to heart failure (HF). Understanding the regulation of cardiomyocyte growth is crucial for the treatment of adverse ventricular remodeling and HF. Cell division cycle 20 (CDC20) is an anaphase-promoting complex activator that is essential for cell division and tumorigenesis, but the role of CDC20 in cardiac hypertrophy is unknown. We aimed to test whether CDC20 participates in the regulation of pathological cardiac hypertrophy and investigate the underlying mechanism in vitro and in vivo. Methods: Male C57BL/6 mice were administered a recombinant adeno-associated virus serotype 9 (rAAV9) vector expressing CDC20 or a siRNA targeting CDC20 and their respective controls by tail intravenous injection. Results: Microarray analysis showed that CDC20 was significantly upregulated in the heart after angiotensin II infusion. Knockdown of CDC20 in cardiomyocytes and in the heart reduced cardiac hypertrophy upon agonist stimulation or transverse aortic constriction (TAC). Conversely, enforced expression of CDC20 in cardiomyocytes and in the heart aggravated the hypertrophic response. Furthermore, we found that CDC20 directly targeted LC3, a key regulator of autophagy, and promoted LC3 ubiquitination and degradation by the proteasome, which inhibited autophagy leading to hypertrophy. Moreover, knockdown of LC3 or inhibition of autophagy attenuated Ang II-induced cardiomyocyte hypertrophy after deletion of CDC20 in vitro. Conclusions: Our study reveals a novel cardiac hypertrophy regulatory mechanism that involves CDC20, LC3 and autophagy, and suggests that CDC20 could be a new therapeutic target for patients with hypertrophic heart diseases.

Aims Chemokine-mediated monocyte infiltration into the damaged heart represents an initial step in inflammation during cardiac remodelling. Our recent study demonstrates a central role for chemokine receptor CXCR2 in monocyte recruitment and hypertension; however, the role of chemokine CXCL1 and its receptor CXCR2 in angiotensin II (Ang II)-induced cardiac remodelling remain unknown. Methods and results Angiotensin II (1000 ng kg-1 min-1) was administrated to wild-type (WT) mice treated with CXCL1 neutralizing antibody or CXCR2 inhibitor SB265610, knockout (CXCR2 KO) or bone marrow (BM) reconstituted chimeric mice for 14 days. Microarray revealed that CXCL1 was the most highly upregulated chemokine in the WT heart at Day 1 after Ang II infusion. The CXCR2 expression and the CXCR2+ immune cells were time-dependently increased in Ang II-infused hearts. Moreover, administration of CXCL1 neutralizing antibody markedly prevented Ang II-induced hypertension, cardiac dysfunction, hypertrophy, fibrosis, and macrophage accumulation compared with Immunoglobulin G (IgG) control. Furthermore, Ang II-induced cardiac remodelling and inflammatory response were also significantly attenuated in CXCR2 KO mice and in WT mice treated with SB265610 or transplanted with CXCR2-deficienct BM cells. Co-culture experiments in vitro further confirmed that CXCR2 deficiency inhibited macrophage migration and activation, and attenuated Ang II-induced cardiomyocyte hypertrophy and fibroblast differentiation through multiple signalling pathways. Notably, circulating CXCL1 level and CXCR2+ monocytes were higher in patients with heart failure compared with normotensive individuals. Conclusions Angiotensin II-induced infiltration of monocytes in the heart is largely mediated by CXCL1-CXCR2 signalling which initiates and aggravates cardiac remodelling. Inhibition of CXCL1 and/or CXCR2 may represent new therapeutic targets for treating hypertensive heart diseases.

Carboxyl terminus of Hsp70-interacting protein (CHIP) is a critical ubiquitin ligase/cochaperone to reduce cardiac oxidative stress, inflammation, cardiomyocyte apoptosis and autophage etc. However, it is unclear whether overexpression of CHIP in the heart would exert protective effects against DOX-induced cardiomyopathy. Cardiac-specific CHIP transgenic (CHIP-TG) mice and the wild-type (WT) littermates were treated with DOX or saline. DOX-induced cardiac atrophy, dysfunction, inflammation, oxidative stress and cardiomyocyte apoptosis were significantly attenuated in CHIP-TG mice. CHIP-TG mice also showed higher survival rate than that of WT mice (40% versus 10%) after 10-day administration of DOX. In contrast, knockdown of CHIP by siRNA in vitro further enhanced DOX-induced cardiotoxic effects. Global gene microarray assay revealed that after DOX-treatment, differentially expressed genes between WT and CHIP-TG mice were mainly involved in apoptosis, atrophy, immune/inflammation and oxidative stress. Mechanistically, CHIP directly promotes ubiquitin-mediated degradation of p53 and SHP-1, which results in activation of ERK1/2 and STAT3 pathways thereby ameliorating DOX-induced cardiac toxicity.

Findings from our laboratory indicate that proinflammatory cytokines and their transcription factor, nuclear factor-kappaB (NF-κB), are increased in the hypothalamic paraventricular nucleus (PVN) and contribute towards the progression of heart failure. In this study, we determined whether NF-κB activation within the PVN contributes to sympathoexcitation via interaction with neurotransmitters in the PVN during the pathogenesis of heart failure. Heart failure was induced in rats by left anterior descending coronary artery ligation. Sham-operated control (SHAM) or heart failure rats were treated for 4 weeks through bilateral PVN infusion with SN50, SN50M or vehicle via osmotic minipump. Rats with heart failure treated with PVN vehicle or SN50M (inactive peptide for SN50) had increased levels of glutamate, norepinephrine (NE), tyrosine hydroxylase (TH), superoxide, gp91(phox) (a subunit of NAD(P)H oxidase), phosphorylated IKKβ and NF-κB p65 activity, and lower levels of gamma-aminobutyric acid (GABA) and the 67-kDa isoform of glutamate decarboxylase (GAD67) in the PVN compared with those of SHAM rats. Plasma levels of cytokines, norepinephrine, epinephrine and angiotensin II, and renal sympathetic nerve activity (RSNA) were increased in heart failure rats. Bilateral PVN infusion of SN50 prevented the decreases in PVN GABA and GAD67, and the increases in RSNA and PVN glutamate, norepinephrine, TH, superoxide, gp91(phox), phosphorylated IKKβ and NF-κB p65 activity observed in vehicle or SN50M-treated heart failure rats. A same dose of SN50 given intraperitoneally did not affect neurotransmitters concentration in the PVN and was similar to vehicle-treated heart failure rats. These findings suggest that NF-κB activation in the PVN modulates neurotransmitters and contributes to sympathoexcitation in rats with ischemia-induced heart failure.

Angiotensin II (Ang II)-induced cardiac remodeling with the underlying mechanisms involving inflammation and fibrosis has been well documented. Cytosolic adaptor caspase recruitment domain 9 (CARD9) has been implicated in the innate immune response. We aimed to examine the role of CARD9 in inflammation and cardiac fibrosis induced by Ang II.Two-month-old CARD9-deficient (CARD9(-/-)) and wild-type (WT) male mice were infused with Ang II (1,500 ng/kg/min) or saline for 7 days. Heart sections were stained with hematoxylin and eosin and Masson trichrome and examined by immunohistochemistry; and activity and protein levels were measured in macrophages obtained from mice.WT mice with Ang II infusion showed a marked increase in CARD9(+) macrophages in the heart, but CARD9(-/-) mice showed significantly suppressed macrophage infiltration and expression of proinflammatory cytokines, including interleukin-1β (IL-1β) and connective tissue growth factor (CTGF). Importantly, Ang II-induced cardiac fibrosis (extracellular matrix and collagen I deposition) was diminished in CARD9(-/-) hearts, as was the expression of transforming growth factor-β (TGF-β) and level of myofibroblasts positive for α-smooth muscle actin (α-SMA). Furthermore, Ang II activation of nuclear factor-κB (NF-κB), JNK and p38 mitogen-activated protein kinases (MAPKs) in WT macrophages was reduced in CARD9(-/-) macrophages.CARD9 plays an important role in regulating cardiac inflammation and fibrosis in response to elevated Ang II.

12/15-Lipoxygenase (LOX) is a member of the LOX family that catalyzes the step from arachidonic acid to hydroxy-eicosatetraenoic acids (HETEs). Previous studies demonstrated that 12/15-LOX plays a critical role in the development of atherosclerosis, hypertension, heart failure, and other diseases; however, its role in myocardial ischemic injury was contraversal. Here, we investigated the inhibition of 12/15-LOX by baicalein on acute cardiac injury and dissected its molecular mechanism. In a mouse model of acute ischemia/reperfusion (I/R) injury, 12/15-LOX was significantly upregulated in the peri-infarct area surrounding the primary infarction. In cultured cardiac myocytes, baicalein suppressed apoptosis and caspase 3 activity in response to simulated ischemia/reperfusion (I/R). Moreover, administration of 12/15-LOX inhibitor, baicalein, significantly attenuated myocardial infarct size induced by I/R injury. Moreover, baicalein treatment significantly inhibited cardiomyocyte apoptosis, inflammatory responses and oxidative stress in the heart after I/R injury. The mechanisms underlying these effects were associated with the activation of ERK1/2 and AKT pathways and inhibition of activation of p38 MAPK, JNK1/2, and NF-kB/p65 pathways in the I/R-treated hearts and neonatal cardiomyoctes. Our data indicated that 12/15-LOX inhibitor baicalein can prevent myocardial I/R injury by modulation of multiple mechanisms, and suggest that baicalein could represent a novel therapeutic drug for acute myocardial infarction.

Atrogin-1/MAFbx is an ubiquitin E3 ligase that regulates myocardial structure and function through the ubiquitin-dependent protein modification. However, little is known about the effect of atrogin-1 activation on the gene expression changes in cardiomyocytes. Neonatal rat cardiomyocytes were infected with adenovirus atrogin-1 (Ad-atrogin-1) or GFP control (Ad-GFP) for 24 hours. The gene expression profiles were compared with microarray analysis. 314 genes were identified as differentially expressed by overexpression of atrogin-1, of which 222 were up-regulated and 92 were down-regulated. Atrogin-1 overexpression significantly modulated the expression of genes in 30 main functional categories, most genes clustered around the regulation of cell death, proliferation, inflammation, metabolism and cardiomyoctye structure and function. Moreover, overexpression of atrogin-1 significantly inhibited cardiomyocyte survival, hypertrophy and inflammation under basal condition or in response to lipopolysaccharide (LPS). In contrast, knockdown of atrogin-1 by siRNA had opposite effects. The mechanisms underlying these effects were associated with inhibition of MAPK (ERK1/2, JNK1/2 and p38) and NF-κB signaling pathways. In conclusion, the present microarray analysis reveals previously unappreciated atrogin-1 regulation of genes that could contribute to the effects of atrogin-1 on cardiomyocyte survival, hypertrophy and inflammation in response to endotoxin, and may provide novel insight into how atrogin-1 modulates the programming of cardiac muscle gene expression.

Background Cardiac cell death and generation of oxidative stress contribute to doxorubicin (DOX)-induced cardiac dysfunction. E3 ligase Nrdp1 plays a critical role in the regulation of cell apoptosis, inflammation and production of reactive oxygen species (ROS), which may contribute to heart failure. However, the role of Nrdp1 in DOX-induced cardiac injury remains to be determined. Methods and Results We examined the effect of Nrdp1 overexpression with DOX treatment in rat neonatal cardiomyocytes and mouse heart tissue. Cardiomyocytes were infected with adenovirus containing GFP (Ad-GFP), Nrdp1 wild-type (Ad-Nrdp1) or the dominant-negative form of Nrdp1 (Ad-Dn-Nrdp1), then treated with DOX for 24 hr. DOX treatment increased cell death and apoptosis, with Ad-Nrdp1 infection enhancing these actions but Ad-Dn-Nrdp1 infection attenuating these effects. Furthermore, 5 days after a single injection of DOX (20 mg/kg, intraperitoneally), Nrdp1 transgenic mice (TG) showed decreased cardiac function and increased apoptosis, autophagy and oxidative stress as compared with wild-type (WT) mice (P