Inhibition of GSDMD Activates Poly(ADP-ribosyl)ation and Promotes Myocardial Ischemia-Reperfusion Injury.

The precise control of cardiomyocyte viability is imperative to combat myocardial ischemia-reperfusion injury (I/R), in which apoptosis and pyroptosis putatively contribute to the process. Recent researches indicated that GSDMD is involved in I/R as an executive protein of pyroptosis. However, its effect on other forms of cell death is unclear. We identified that GSDMD and GSDMD-N levels were significantly upregulated in the I/R myocardium of mice. Knockout of GSDMD conferred the resistance of the hearts to reperfusion injury in the acute phase of I/R but aggravated reperfusion injury in the chronic phase of I/R. Mechanistically, GSDMD deficiency induced the activation of PARylation and the consumption of NAD+ and ATP, leading to cardiomyocyte apoptosis. Moreover, PJ34, a putative PARP-1 inhibitor, reduced the myocardial injury caused by GSDMD deficiency. Our results reveal a novel action modality of GSDMD in the regulation of cardiomyocyte death; inhibition of GSDMD activates PARylation, suggesting the multidirectional role of GSDMD in I/R and providing a new theory for clinical treatment.

S-nitrosylation of c-Jun N-terminal kinase mediates pressure overload-induced cardiac dysfunction and fibrosis.

Cardiac fibrosis (CF) is an irreversible pathological process that occurs in almost all kinds of cardiovascular diseases. Phosphorylation-dependent activation of c-Jun N-terminal kinase (JNK) induces cardiac fibrosis. However, whether S-nitrosylation of JNK mediates cardiac fibrosis remains an open question. A biotin-switch assay confirmed that S-nitrosylation of JNK (SNO-JNK) increased significantly in the heart tissues of hypertrophic patients, transverse aortic constriction (TAC) mice, spontaneously hypertensive rats (SHRs), and neonatal rat cardiac fibroblasts (NRCFs) stimulated with angiotensin II (Ang II). Site to site substitution of alanine for cysteine in JNK was applied to determine the S-nitrosylated site. S-Nitrosylation occurred at both Cys116 and Cys163 and substitution of alanine for cysteine 116 and cysteine 163 (C116/163A) inhibited Ang II-induced myofibroblast transformation. We further confirmed that the source of S-nitrosylation was inducible nitric oxide synthase (iNOS). 1400 W, an inhibitor of iNOS, abrogated the profibrotic effects of Ang II in NRCFs. Mechanistically, SNO-JNK facilitated the nuclear translocation of JNK, increased the phosphorylation of c-Jun, and induced the transcriptional activity of AP-1 as determined by chromatin immunoprecipitation and EMSA. Finally, WT and iNOS-/- mice were subjected to TAC and iNOS knockout reduced SNO-JNK and alleviated cardiac fibrosis. Our findings demonstrate an alternative mechanism by which iNOS-induced SNO-JNK increases JNK pathway activity and accelerates cardiac fibrosis. Targeting SNO-JNK might be a novel therapeutic strategy against cardiac fibrosis.

S-nitrosylation of Hsp90 promotes cardiac hypertrophy in mice through GSK3ß signaling.

Cardiac hypertrophy, as one of the major predisposing factors for chronic heart failure, lacks effective interventions. Exploring the pathogenesis of cardiac hypertrophy will reveal potential therapeutic targets. S-nitrosylation is a kind of posttranslational modification that occurs at active cysteines of proteins to mediate various cellular processes. We here identified heat shock protein 90 (Hsp90) as a highly S-nitrosylated target in the hearts of rodents with hypertrophy, and the role of Hsp90 in cardiac hypertrophy remains undefined. The S-nitrosylation of Hsp90 (SNO-Hsp90) levels were elevated in angiotensin II (Ang II)- or phenylephrine (PE)-treated neonatal rat cardiomyocytes (NRCMs) in vitro as well as in cardiomyocytes isolated from mice subjected to transverse aortic constriction (TAC) in vivo. We demonstrated that the elevated SNO-Hsp90 levels were mediated by decreased S-nitrosoglutathione reductase (GSNOR) expression during cardiac hypertrophy, and delivery of GSNOR adeno-associated virus expression vectors (AAV9-GSNOR) decreased the SNO-Hsp90 levels to attenuate cardiac hypertrophy. Mass spectrometry analysis revealed that cysteine 589 (Cys589) might be the S-nitrosylation site of Hsp90. Delivery of the mutated AAV9-Hsp90-C589A inhibited SNO-Hsp90 levels and attenuated cardiac hypertrophy. We further revealed that SNO-Hsp90 led to increased interaction of glycogen synthase kinase 3ß (GSK3ß) and Hsp90, leading to elevated GSK3ß phosphorylation and decreased eIF2Bε phosphorylation, thereby aggravating cardiac hypertrophy. Application of GSK3ß inhibitor TWS119 abolished the protective effect of Hsp90-C589A mutation in Ang II-treated NRCMs. In conclusion, this study demonstrates a critical role of SNO-Hsp90 in cardiac hypertrophy, which may be of a therapeutic target for cardiac hypertrophy treatment.

Loganin Inhibits Angiotensin II-Induced Cardiac Hypertrophy Through the JAK2/STAT3 and NF-κB Signaling Pathways.

Loganin is an iridoid glycoside extracted from Cornus officinalis, which is a traditional oriental medicine, and many biological properties of loganin have been reported. Nevertheless, it is not clear whether loganin has therapeutic effect on cardiovascular diseases. Hence, the aim of the present study was to investigate the effect of loganin on Ang II-induced cardiac hypertrophy. In the present study, we reported for the first time that loganin inhibits Ang II-provoked cardiac hypertrophy and cardiac damages in H9C2 cells and in mice. Furthermore, loganin can achieve cardioprotective effects through attenuating cardiac fibrosis, decreasing pro-inflammatory cytokine secretion, and suppressing the phosphorylation of critical proteins such as JAK2, STAT3, p65, and IκBα. Besides, the outstanding findings of the present study were to prove that loganin has no significant toxicity or side effects on normal cells and organs. Based on these results, we conclude that loganin mitigates Ang II-induced cardiac hypertrophy at least partially through inhibiting the JAK2/STAT3 and NF-κB signaling pathways. Accordingly, the natural product, loganin, might be a novel effective agent for the treatment of cardiac hypertrophy and heart failure.

No association between tumor laterality and cardiac-related mortality in breast cancer patients after radiotherapy: a population-based study.

INTRODUCTION: To assess the effect of tumor laterality to cardiac-related deaths of breast cancer in the current radiation practices using a large modern population-based study. METHODS: Women diagnosed with breast cancer from 2000 to 2008 were included using the current Surveillance, Epidemiology, and End Results database. The primary outcome of this study was the cardiac-related mortality. Multivariate analysis was performed using the Cox proportional hazards model to analyze the cardiac-related mortality including demographic, clinicopathologic, and treatment factors. RESULTS: We identified 168,761 breast cancer patients, including 85,006 (50.4%) patients with left-sided tumors and 83,755 (49.6%) patients with right-sided tumors. The median follow-up period was 8.8 years. The 10-year cardiac-related mortality was 2.3% and 2.3% in left- and right-sided tumors, respectively (P=0.685). The results indicated that patients with older age, non-Hispanic Black, receipt of mastectomy, and married status were the independent adverse factors for cardiac-related mortality. However, left-sided tumors were not associated to a higher risk of cardiac-related mortality than right-sided tumors following postoperative radiotherapy (right vs left, hazard ratios 1.025, 95% CI 0.856-1.099, P=0.484). The risk of cardiac-related mortality in the entire cohort was increased with the extension of follow-up time. However, there was still not significantly different between left- and right-sided tumors. Subgroup analysis also found no association between tumor laterality and cardiac-related mortality after postoperative radiotherapy based on various demographics and treatment factors. CONCLUSION: With a median follow-up of 8.8 years, no significant differences were found in cardiac-related mortality between left- and right-sided tumors under current radiation practices of breast cancer patients.

Rbm24 Regulates Alternative Splicing Switch in Embryonic Stem Cell Cardiac Lineage Differentiation.

The transition of embryonic stem cell (ESC) pluripotency to differentiation is accompanied by an expansion of mRNA and proteomic diversity. Post-transcriptional regulation of ESCs is critically governed by cell type-specific splicing. However, little is known about the splicing factors and the molecular mechanisms directing ESC early lineage differentiation. Our study identifies RNA binding motif protein 24 (Rbm24) as a key splicing regulator that plays an essential role in controlling post-transcriptional networks during ESC transition into cardiac differentiation. Using an inducible mouse ESC line in which gene expression could be temporally regulated, we demonstrated that forced expression of Rbm24 in ESCs dramatically induced a switch to cardiac specification. Genome-wide RNA sequencing analysis identified more than 200 Rbm24-regulated alternative splicing events (AS) which occurred in genes essential for the ESC pluripotency or differentiation. Remarkably, AS genes regulated by Rbm24 composed of transcriptional factors, cytoskeleton proteins, and ATPase gene family members which are critical components required for cardiac development and functionality. Furthermore, we show that Rbm24 regulates ESC differentiation by promoting alternative splicing of pluripotency genes. Among the Rbm24-regulated events, Tpm1, an actin filament family gene, was identified to possess ESC/tissue specific isoforms. We demonstrated that these isoforms were functionally distinct and that their exon AS switch was essential for ESC differentiation. Our results suggest that ESC's switching into the differentiation state can be initiated by a tissue-specific splicing regulator, Rbm24. This finding offers a global view on how an RNA binding protein influences ESC lineage differentiation by a splicing-mediated regulatory mechanism. Stem Cells 2016;34:1776-1789.

[The effect of tanshinone II A on the transmembrance action potential of myocardial cells in LQT2 rabbit models].

OBJECTIVE: To determine the effect of tanshinone II A on the transmembrance action potential of three layers of myocardial cells in LQT2 rabbit models. METHODS: Whole-cell patch clamp technique was used to record the action potential duration 90 (APD90) and the transmural dispersion of repolarization (TDR) of the epicardium, mid-myocardium and endocardium in the LQT2 rabbits. RESULTS: Of the three layers of myocardial cells, the mid-myocardium had the longest APD90 and the epicardium had the shortest APD90. The APD90 of all three layers of myocardial cells were shortened with infusion of 10 mg/mL tanshinone II A. Their TDR values also reduced by the infusion. CONCLUSION: Tanshinone II A shortens APD90 and reduces TDR values.

Human cytomegalovirus linked to stroke in a Chinese population.

AIM: Human cytomegalovirus (HCMV) is implicated in several cardiovascular disorders, including atherosclerosis, coronary heart disease, and cardiac transplant arteriopathy. We aimed to evaluate the relationship between HCMV and stroke. METHODS: Real-time polymerase chain reaction (PCR) and ELISA were performed on plasma samples isolated from 200 patients diagnosed with stroke and 200 controls. All participants belonged to the Stroke Hypertension Investigation in Genetics (SHINING) study. RESULTS: HCMV seropositivity was higher in the stroke group than in controls (55.0% vs. 23.5%; P < 0.0001). The presence of HCMV DNA increased the risk of stroke (unadjusted odds ratio [OR], 3.98; 95% confidence interval [CI], 2.59 to 6.11; P < 0.0001). Risks were also increased for the subtypes ischemic stroke (unadjusted OR, 4.01; 95% CI, 2.57-6.24; P < 0.0001) and hemorrhagic stroke (unadjusted OR, 3.80; 95% CI, 1.64-8.78; P= 0.0018). Increased risk with HCMV remained significant after adjustment for age, sex, body mass index, hypertension, and smoking (ischemic stroke: adjusted OR, 4.07; 95% CI, 2.52-6.32; P < 0.0001; hemorrhagic stroke: adjusted OR, 3.88; 95% CI, 1.61-9.36; P= 0.0026). CONCLUSIONS: We demonstrate a novel link between HCMV infection and stroke. These findings may provide important insights into the pathogenesis of stroke.

Firebird and cypher sirolimus-eluting stents and bare metal stents in treatment of very long coronary lesions.

BACKGROUND: As a kind of sirolimus-eluting stent (SES) made in China, Firebird SES is more effective than bare metal stent (BMS) and not inferior to Cypher SES for short coronary lesions in terms of reduction of restenosis and revascularization. However, Firebird SES does not show any benefits in patients with a very long coronary lesion (VLCL). The present study was undertaken to evaluate the safety and efficacy of Firebird SES for VLCL by comparison of Cypher SES and BMS. METHODS: In this prospective, nonrandomized and comparative study, eligible patients with de novo coronary lesion (> or = 30 mm) between January 2005 and June 2006 were allocated into Firebird SES group, Cypher SES group or BMS group. They were subjected to an angiographic follow-up of 6 months and a clinical follow-up of 12 months. The primary endpoints constitute the in-stent and in-segment restenosis rates at 6 months. The secondary endpoint was defined as a major adverse cardiovascular event (MACE) that was a 12-month combined endpoint of all-cause deaths, reinfarction or in-stent thrombosis, and target-lesion revascularization. The 12-month in-stent thrombosis was also evaluated to address the safety of Firebird SES implantation exceptionally. RESULTS: A total of 468 patients were assessed for eligibility. Of 113 patients who were finally included according to the prior inclusion and exclusion criteria, 39 (41 lesions) were treated with Firebird SES, 37 (39 lesions) with Cypher SES, and 37 (37 lesions) with BMS. There were no significant differences in the baseline characteristics between the three groups; but there were longer lesions, more frequent use of overlapping stent in the Firebird SES group and the Cypher SES group. Angiographic follow-up showed that the rates of binary stenosis were similar between the Firebird SES group and the Cypher SES group (in-segment: 14.6% vs 12.8%, relative risk (RR) 1.14, P = 0.81; in-stent: 9.8% vs 10.3%, RR 0.95, P = 0.94), and significantly lower than those in the BMS group (in-segment: vs. 36.1%, RR 0.41 or 0.36, P = 0.04 or 0.03, respectively; in-stent: vs 30.6%, RR 0.32 or 0.34, P = 0.03 or 0.04, respectively). The total MACE rate up to 12 months was also similar in both SES groups (7.7% vs 5.4%, P = 1.000), and significantly lower than that in the BMS group (27.0%, P = 0.034 or 0.024, respectively). The in-stent thrombosis rate in the follow-up period was 2.6% in the Firebird SES group, not higher in the Cypher SES and BMS groups (2.7% and 2.7%, respectively, P = 1.000). CONCLUSIONS: In the treatment of VLCL, Firebird SES would be safer and more effective than BMS. Firebird SES may be not inferior to Cypher SES in terms of restenosis and MACE.

Interventricular septum motion abnormalities: unexpected echocardiographic changes of Brugada syndrome.

BACKGROUND: There remains controversy about whether Brugada syndrome (BS) has structural heart changes. We occasionally noted that a patient with BS had a quite unusual regional wall motion abnormality at the basal segment of the interventricular septum (IVS) during echocardiographic examination. The unexpected finding promoted us to reexamine our patients with BS by echocardiographic interrogation in the present study. METHODS: Patients with BS (n = 11), patients with complete right bundle branch block (RBBB) (n = 11), and control subjects (n = 11) were enrolled in this study. Two-dimensional echocardiography (2DE) was performed to obtain parasternal left ventricular long axis view on which M-mode scanning line was adjusted to be perpendicular to the basal segment of IVS for delineation of the segmental motion curve, with a simultaneously electrocardiographic tracing. RESULTS: 2DE revealed a rapid swing motion shifting toward the right ventricle of the IVS basal segment at early systole in 73% (8/11) patients with BS, which was further confirmed on the M-mode curve evidenced by an early systolic notch toward the right ventricle. The position of the notch corresponded to C-point on the mitral motion curve, lasting for (53 +/- 5) ms. There were no similar changes both in patients with RBBB and in the control subjects. CONCLUSION: IVS basal motion abnormalities at early-systolic phase may be the novel finding of BS.

Changes of IK, ATP current density and allosteric modulation during chronic atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common supraventricular arrhythmia in clinical practice. Chronic atrial fibrillation (CAF) is associated with ionic remodeling. However, little is known about the activity of ATP-sensitive potassium current (IK, ATP) during CAF. So we studied the changes of IK, ATP density and allosteric modulation of ATP-sensitivity by intracellular pH during CAF. METHODS: Myocardium samples were obtained from the right auricular appendage of patients with rheumatic heart disease complicated with valvular disease in sinus rhythm (SR) or CAF. There were 14 patients in SR group and 9 patients in CAF group. Single atrial cells were isolated using an enzyme dispersion technique. IK, ATP was recorded using the whole-cell and inside-out configuration of voltage-clamp techniques. In whole-cell model, myocytes of SR and CAF groups were perfused with simulated ischemic solution to elicit IK, ATP. In inside-out configuration, the internal patch membranes were exposed to different ATP concentrations in pH 7.4 and 6.8. RESULTS: Under simulated ischemia, IK, ATP current density of CAF group was significantly higher than in SR group [(83.5 +/- 10.8) vs. (58.7 +/- 8.4) pA/pF, P < 0.01]. IK, ATP of the two groups showed ATP concentration-dependent inhibition. The ATP concentration for 50% current inhibition (IC50) for the SR group was significantly different in pH 7.4 and pH 6.8 (24 vs. 74 micromol/L, P < 0.01). The IC50 did not change significantly in CAF group when the pH decreased from 7.4 to 6.8. CONCLUSIONS: During CAF, IK, ATP current density was increased and its allosteric modulation of ATP-sensitivity by intracellular pH was diminished.