S-Nitrosylation of Akt by organic nitrate delays revascularization and the recovery of cardiac function in mice following myocardial infarction.

The effects of long-term nitrate therapy are compromised due to protein S-Nitrosylation, which is mediated by nitric oxide (NO). This study is to determine the role of Akt S-Nitrosylation in the recovery of heart functions after ischaemia. In recombinant Akt protein and in HEK293 cells, NO donor decreased Akt activity and induced Akt S-Nitrosylation, but was abolished if Akt protein was mutated by replacing cysteine 296/344 with alanine (Akt-C296/344A). In endothelial cells, NO induced Akt S-Nitrosylation, reduced Akt activity and damaged multiple cellular functions including proliferation, migration and tube formation. These alterations were ablated if cells expressed Akt-C296/344A mutant. In Apoe-/- mice, nitroglycerine infusion increased both Akt S-Nitrosylation and infarct size, reduced Akt activity and capillary density, and delayed the recovery of cardiac function in ischaemic hearts, compared with mice infused with vehicle. Importantly, these in vivo effects of nitroglycerine in Apoe-/- mice were remarkably prevented by adenovirus-mediated enforced expression of Akt-C296/344A mutant. In conclusion, long-term usage of organic nitrate may inactivate Akt to delay ischaemia-induced revascularization and the recovery of cardiac function through NO-mediated S-Nitrosylation.

Glycyrrhizin protects rat heart against ischemia-reperfusion injury through blockade of HMGB1-dependent phospho-JNK/Bax pathway.

AIM: Glycyrrhizin (GL) has been found to inhibit extracellular HMGB1 cytokine's activity, and protect spinal cord, liver and brain against I/R-induced injury in experimental animals. The purpose of this study was to investigate the protective effect of GL in rat myocardial I/R-induced injury and to elucidate the underlying mechanisms. METHODS: Male adult Sprague-Dawley rats underwent a 30-min left coronary artery occlusion followed by a 24-h reperfusion. The rats were treated with glycyrrhizin or glycyrrhizin plus recombinant HMGB1 after 30 min of ischemia and before reperfusion. Serum HMGB1, TNF-α and IL-6 levels, and hemodynamic parameters were measured at the onset and different time points of reperfusion. At the end of the experiment, the heart was excised, and the infarct size and histological changes were examined. The levels of Bcl2, Bax and cytochrome c, as well as phospho-ERK1/2, phospho-JNK and phospho-P38 in the heart tissue were evaluated using Western blot analysis, and myocardial caspase-3 activity was measured colorimetrically using BD pharmingen caspase 3 assay kit. RESULTS: Intravenous administration of GL (10 mg/kg) significantly reduced the infarct size, but did not change the hemodynamic parameters at different time points during reperfusion. GL significantly decreased the levels of serum HMGB1, TNF-α and IL-6. GL changed the distribution of Bax and cytochrome c expression between the mitochondrial and cytosolic fractions in the heart tissue, resulting in inhibition of myocardial apoptosis. Moreover, expression of phospho-JNK, but not ERK1/2 and P38 was decreased by GL in the heart tissue. All of the effects produced by GL treatment were reversed by co-administration with the recombinant HMGB1 (100 µg). Intravenous administration of SP600125, a selective phospho-JNK inhibitor (0.5 mg/kg), attenuated HMGB1-dependent Bax translocation and the subsequent apoptosis. CONCLUSION: These results demonstrate that GL alleviates rat myocardial I/R-induced injury via directly inhibiting extracellular HMGB1 cytokine activity and blocking the phospho-JNK/Bax pathway.

[Roles of monocyte chemoattractant protein-1, RANTES and Fractalkine on promoting vulnerability of atherosclerotic plaques].

OBJECTIVE: To elucidate the roles of monocyte chemotactic factors (MCP-1, RANTES and Fractalkine) on the vulnerability of atherosclerotic plaques in patients with stable (SAP) and unstable angina pectoris (UAP). METHODS: Patients with SAP (n = 50) and UAP (n = 50) underwent coronary angiography (CAG) and intravenous ultrasound (IVUS) were included in the study. Monocyte chemotaxis was assayed by the transwell chamber. Concentrations of hs-CRP, MCP-1, RANTES and Fractalkine were measured by Enzyme-linked-immunosorbent assay (ELISA). mRNA expression of MCP-1, RANTES and Fractalkine in the monocytes was detected by RT-PCR. RESULTS: IVUS evidenced soft lipid plaques in 48% UAP patients and in 16% SAP patients (P < 0.05). SAP patients had mainly fibrous and mixed plaques. Plaque burden and vascular remodeling index were significantly higher in UAP patients than in SAP patients (P < 0.01). The averaged number of migrated monocytes in the UAP patients were higher than that in patients with SAP (P < 0.01). Concentration of hs-CRP, MCP-1, RANTES and Fractalkine were significantly higher in UAP patients than those of SAP patients (P < 0.05 or P < 0.01). mRNA expression of MCP-1, RANTES and Fractalkine in patients with UAP was significantly higher than those of SAP patients (P < 0.05). CONCLUSION: Upregulated monocyte chemotactic factors (MCP-1, RANTES and Fractalkine) might promote coronary plaque vulnerability in UAP patients.

[Two novel mutations of GLA gene in Chinese patients with Fabry disease].

OBJECTIVE: To observe the disease-causing GLA gene mutations in Chinese patients with Fabry disease and the correlation between the genotype and phenotype. METHODS: DNA from 2 Chinese patients with Fabry disease and their relatives were collected. The seven exons and nonjunctional regions of GLA gene were amplified with polymerase chain reaction and the products were sequenced. The correlation between the genotype and phenotype was analyzed. RESULTS: Two mutations, G1168A and G1170A, located in 5' untranslated regions (5'UTR) were identified in the two probands and the two mutations were absent in normal controls. Three patients with the same genotype were found in the pedigree with G1168A mutation and there was no gene mutation carrier in the pedigree with G1170A mutation. Symptoms of the disease are less in female patients than that in male patients. CONCLUSION: GLA gene mutation in 5'UTR may also be involved in the disease process of patients with Fabry disease and the phenotype is partly affected by gender.

[A novel missense mutation, K124N, in the troponin T gene of Chinese populations with hypertrophic cardiomyopathy].

OBJECTIVE: To study the cardiac troponin T (TNNT2) gene mutation in Chinese patients with hypertrophic cardiomyopathy (HCM) and to analyze the correlation between the genotype and phenotype. METHODS: Specimens of peripheral blood were collected from 71 unrelated Chinese probands with HCM, aged 40 +/- 18. The genome DNA was extracted. Single-strand conformation polymorphism gel analysis of the polymerase chain reaction-amplified products was conducted to search for mutations in the exons 8, 9, 10, 11, and 16 of the TNNT2 gene. Relevant clinical data were collected. One hundred normal persons, aged 44 +/- 14, were used as controls. RESULTS: A missense mutation, K124N, in the exon 9 of the TNNT2 gene was identified in a 41-year-old female patient with HCM and failed to be detected in the 100 normal controls, which suggested the disease-causing mutation. The patient began to have the symptoms of chest distress and palpitation since the age of 38, presented moderate hypertrophy of the intraventricular septum, and did not have a family history of sudden cardiac death. CONCLUSION: A novel missense mutation of troponin T gene has been identified. Mutation in tail part of cardiac troponin T, essential for it's binding function, causes the disease of HCM. Correlative analysis confirms the genetic heterogeneity of the disease.