Effect of osthol on apoptosis and bone resorption of osteoclasts cultured in vitro / 药学学报

This study is to investigate the effect of osthol on osteoclasts' activity, bone resorption as well as apoptosis in vitro, and explore the mechanism of osthol in preventing osteoporosis. Osteoclasts were separated from long-limb bones of new born rabbits, cultured in 24-well plate with glass slices and bone slices, and treated by 1 x 10(-5) mol x L(-1) osthol. Osteoclasts were identified by observing live cells with phase contrast microscope, HE staining, TRAP staining and toluidine blue staining of bone resorption pits. The numbers of bone resorption pits were counted as well as the surface area of bone resorption on bone slice. Osteoclasts were stained with acridine orange to detect the cell apoptosis. The ratio of apoptotic osteoclasts was observed under fluorescence microscope. The gene expression of RANKL, OPG, TRAP and p-JNK1/2 protein expression were examined using real time PCR and Western blotting, respectively. Comparing with the control group without osthol, the rates of apoptotic osteoclasts increased obviously and the number and area of bone resorption pits decreased evidently with 1 x 10(-5) mol x L(-1) osthol. There is significant difference between control group and experiment group treated by 1 x 10(-5) mol x L(-1) osthol. Therefore, the osthol through RANK+RANKL/TRAF6/Mkk/JNK signal pathway inhibits the osteoclasts activity, enhances osteoclasts apoptotic and inhibits the bone resorption.

Activation of c-Jun N-terminal kinase 1/2 regulated by nitric oxide is associated with neuronal survival in hippocampal neurons in a rat model of ischemia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>C-Jun N-terminal kinase (JNK) signaling pathway plays a critical role in cerebral ischemia. Although the mechanistic basis for this activation of JNK1/2 is uncertain, oxidative stress may play a role. The purpose of this study was to investigate whether the activation of JNK1/2 is associated with the production of endogenous nitric oxide (NO).</p><p><b>METHODS</b>Ischemia and reperfusion (I/R) was induced by cerebral four-vessel occlusion. Sprague-Dawley (SD) rats were divided into 6 groups: sham group, I/R group, neuronal nitric oxide synthase (nNOS) inhibitor (7-nitroindazole, 7-NI) given group, inducible nitric oxide synthase (iNOS) inhibitor (2-amino-5,6-dihydro-methylthiazine, AMT) given group, sodium chloride control group, and 1% dimethyl sulfoxide (DMSO) control group. The levels of protein expression and phospho-JNK1/2 were detected by Western blotting and the survival hippocampus neurons in CA1 zone were observed by cresyl violet staining.</p><p><b>RESULTS</b>The study illustrated two peaks of JNK1/2 activation occurred at 30 minutes and 3 days during reperfusion. 7-NI inhibited JNK1/2 activation during the early reperfusion, whereas AMT preferably attenuated JNK1/2 activation during the later reperfusion. Administration of 7-NI and AMT can decrease I/R-induced neuronal loss in hippocampal CA1 region.</p><p><b>CONCLUSION</b>JNK1/2 activation is associated with endogenous NO in response to ischemic insult.</p>

C-jun N-terminal kinase-mediated signaling is essential for Staphylococcus aureus-induced U937 apoptosis / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the effect of SP600125, a specific c-jun N-terminal protein kinase (JNK) inhibitor, on Staphylococcus aureus (S. aureus)-induced U937 cell death and the underlying mechanism.</p><p><b>METHODS</b>The human monocytic U937 cells were treated with S. aureus at different time with or without SP600125. Cell apoptosis was analyzed by flow cytometry. JNK, Bax, and caspase-3 activities were detected by Western blotting.</p><p><b>RESULTS</b>S. aureus induced apoptosis in cultured U937 cells in a time-dependent manner. Expression of Bax and phospho-JNK significantly increased in S. aureus-treated U937 cells, and the level of activated caspase-3 also increased in a time-dependent manner. Inhibition of JNK with SP600125 significantly inhibited S. aureus-induced apoptosis in U937 cells.</p><p><b>CONCLUSIONS</b>S. aureus can induce apoptosis in U937 cells by phosphorylation of JNK and activation of Bax and caspase-3. SP600125 protects U937 cells from apoptosis induced by S. aureus via inhibiting the activity of JNK.</p>

Benzo (a) pyrene-induced human embryo lung cell cycle alterations through positive regulation of mitogen-activated protein kinase signal pathways / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the effects of benzo(a)pyrene (BaP) on the cell cycle distribution and activities of mitogen-activated protein kinase (MAPK) signal molecules (ERK1/2, JNK1/2 and p38) in human embryo lung cells (HELF), and to investigate the relationship between alterations of MAPK protein phosphorylation and the cell cycle distributions.</p><p><b>METHODS</b>The phosphorylation of MAPK were induced by exposing HELF cells to BaP at 0.1, 0.5, 2.5 and 12.5 micromol/L. The phosphorylation and protein expression levels of ERK1/2, JNK1/2 and p38 were determined through western-blotting assay. And the flow cytometry assay was used to measure the cell cycle effects in HELF cells after treatment with 2.5 micromol/L BaP for 24 h.</p><p><b>RESULTS</b>The phosphorylation levels of ERK1/2, JNK1/2 and p38 were significantly increased through BaP exposure. In addition, the phosphorylation of these three MAPKs has similar alteration pattern. We found that exposure of cells to 2.5 microM of BaP for 24 h resulted in a decrease of G(0) and G(1) population by 11.9% (F = 41.38, P < 0.01) and an increase of S population by 17.2% (F = 68.13, P < 0.01). Three chemical inhibitors of MAPK (AG126, SP600125 and SB203580) could significantly inhibit the cell cycle alteration because of BaP treatment.</p><p><b>CONCLUSION</b>ERK1/2, JNK1/2 and p38 could positively regulate the BaP independently induced cell cycle alterations.</p>