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.

[Protective effect of Wuziyanzong Pills on rats with experimental oligoasthenospermia and its action mechanism].

OBJECTIVE: To investigate the protective effect of Wuziyanzong Pills (WYP) in the rat model of oligoasthenospermia (OAS) and its action mechanism. METHODS: Sixty male SD rats were equally randomized into six groups: normal control, OAS model, Shengjing Capsules (1.6 g per kg of the body weight), low-dose WYP (1 g per kg of the body weight), medium-dose WYP (2 g per kg of the body weight), and high-dose WYP (4 g per kg of the body weight). The OAS model was established by intragastric administration of Tripterygium glucoside at 30 mg per g per d for 6 weeks. From the 3rd week of modeling, the rats of the medication groups were treated intragastrically with corresponding drugs for 4 weeks. Then all the rats were sacrificed for measurement of the testicular and epididymal organ coefficients, examination of epididymal sperm quality and apoptosis, and detection of the openness of the sperm mitochondrial permeability transition pore (MPTP). Histopathological changes in the testis were observed by HE staining and the apoptosis of spermatogenic cells determined by Hochest staining. RESULTS: WYP obviously improved the organ coefficients of the testis and epididymis, increased sperm concentration, motility and viability, decreased the apoptosis of spermatogenic cells, and inhibited the abnormal openness of MPTP in the OAS model rats. HE staining showed that the number and levels of spermatogenic cells were significantly increased while Hochest staining manifested that the apoptosis of spermatogenic cells was remarkably inhibited in the seminiferous tubules of the testis in the WYP-treated rats. CONCLUSIONS: WYP can improve sperm quality and reduce the apoptosis of spermatogenic cells (including sperm) in OAS model rats, which may be related with its inhibitory effect on the abnormal openness of MPTP.