Quercetin Prevents In Vivo and In Vitro Myocardial Hypertrophy Through the Proteasome-GSK-3 Pathway.

PURPOSE: Quercetin, a flavonoid, has been reported to ameliorate cardiovascular diseases, such as cardiac hypertrophy. However, the mechanism is not completely understood. In this study, a mechanism related to proteasome-glycogen synthesis kinase 3 (GSK-3) was elucidated in rats and primary neonatal cardiomyocytes. METHODS: Rats were subjected to sham or constriction of abdominal aorta surgery groups and treated with or without quercetin for 8 weeks. Angiotensin II (Ang II)-induced primary cardiomyocytes were cultured with quercetin treatment or not for 48 h. Echocardiography, real-time RT-PCR, histology, immunofluorescence, and Western blotting were conducted. Proteasome activities were also detected using a fluorescent peptide substrate. RESULTS: Echocardiography showed that quercetin prevented constriction of abdominal aorta-induced cardiac hypertrophy and improved the cardiac diastolic function. In addition, quercetin also significantly reduced the Ang II-induced hypertrophic surface area and atrial natriuretic factor (ANF) mRNA level in primary cardiomyocytes. Proteasome activities were obviously inhibited in the quercetin-treated group both in vivo and in vitro. Quercetin also decreased the levels of proteasome subunit beta type (PSMB) 1, PSMB2, and PSMB5 of the 20S proteasome as well as the levels of proteasome regulatory particle (Rpt) 1 and Rpt4 of the 19S proteasome. In particular, the PSMB5 level in the nucleus was reduced after quercetin treatment. Furthermore, phosphorylated GSK-3α/ß (inactivation of GSK-3) was decreased, which means that GSK-3 activity was increased. The phosphorylation levels of upstream AKT (PKB (protein kinase B)) and liver kinase B1/AMP activated protein kinase (LKB1/AMPKα) and those of downstream extracellular signal-regulated kinase (ERK), histone H3, ß-catenin, and GATA binding protein 4 (GATA4) were reduced after quercetin treatment, while hypertrophy was reversed after treatment with the GSK-3 inhibitor. CONCLUSION: In summary, quercetin prevents cardiac hypertrophy, which is related to proteasome inhibition and activation of GSK-3α/ß. Upstream (AKT, LKB1/AMPKα) and downstream hypertrophic factors, such as ERK, histone H3, ß-catenin, and GATA4, may also be involved.

AMP-activated protein kinase-dependent autophagy mediated the protective effect of sonic hedgehog pathway on oxygen glucose deprivation-induced injury of cardiomyocytes.

Sonic hedgehog (Shh) pathway has been reported to protect cardiomyocytes in myocardial infarction (MI), but the underlying mechanism is not clear. Here, we provide evidence that Shh pathway induces cardiomyocytes survival through AMP-activated protein kinase-dependent autophagy. Shh pathway agonist SAG increased the expression of LC3-II, and induced the formation of autophagosomes in cultured H9c2 cardiomyocytes under oxygen glucose deprivation (OGD) 1 h and 4 h. Moreover, SAG induced a profound AMP-activated protein kinase (AMPK) activation, and then directly phosphorylated and activated the downstream autophagy initiator Ulk1, independent of the autophagy suppressor mammalian target of rapamycin (mTOR) complex 1. Taken together, our results have shown that Shh activates AMPK-dependent autophagy in cardiomyocytes under OGD, suggesting a role of autophagy in Shh-induced cellular protection.

Development of a colloidal gold-based immunochromatographic test strip for the rapid, on-site detection of Pseudomonas aeruginosa in clinical samples.

BACKGROUND: Current procedures for the detection of Pseudomonas aeruginosa require sophisticated equipment, skilled technicians, and a great deal of time. Immunochromatography assays (ICA) are simple and rapid diagnostic procedures that can be performed and interpreted on the spot or at the bedside without a machine. METHODS: We developed a rapid, 1-step immunochromatographic test strip that is well suited to the on-site detection of P. aeruginosa with high sensitivity and specificity. In brief, a monoclonal antibody targeting the outer membrane protein F (OprF) of P. aeruginosa, 3C3B5, was conjugated to colloidal gold and used as a detection antibody. An OprF polyclonal antibody was developed as the capture antibody. Eighty-three clinical samples were examined for P. aeruginosa by rapid 1-step ICA and compared with Multiplex-polymerase chain reaction (M-PCR). RESULTS: The detection limit of this method is 5 × 10(5) CFU/ml for P. aeruginosa and 10 ng/ml for the OprF protein. The immunochromatographic strip test demonstrated a slightly lower sensitivity (84.8%), but a similar specificity (100%), to multi-PCR, which is an accurate method for the detection of P. aeruginosa in the laboratory. We observed no cross-reactivity with non-P. aeruginosa bacterial microbes. The detection of P. aeruginosa by the ICA strip can be completed within 5-10 min and is at least 10-fold faster than M-PCR. CONCLUSIONS: The ICA test strip developed in this study has proved to be a rapid, simple, effective and economical method for the detection of P. aeruginosa infection in clinical samples. To our knowledge, this is the first report of an ICA method being used to detect P. aeruginosa.