Involvement of ERK1/2 and p38 MAPK in up-regulation of 14-3-3 protein induced by hydrogen peroxide preconditioning in PC12 cells

Objective To investigate the protective effects of hydrogen peroxide preconditioning （HPP） on the pheochromocytoma （PC12） cells treated with 1-methyl-4-phenylpyridinium （MPP^＋） and to explore the potential mechanisms. Methods The viability and apoptosis of PC 12 cells were determinded by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） assay and 4′,6′-diamidino-2-phenylindole （DAPI） staining, respectively. The expressions of 14-3-3 protein and phospholylated p38 mitogen-activated protein kinase （MAPK） were determined by Western blot. Enzyme-linked immunosorbent assay （ELISA） was used to measure the activity of extracellular signal-regulated protein kinase 1/2 （ERK1/2）. Results The cell viability decreased and the number of apoptotic cells increased dramatically in MPP^＋ group compared with that in Control group. HPP induced a significant increase in cell viability and a marked decrease in population of apoptotic cells of the MPP^＋- treated PC 12 cells, accompanied with up-regulation of 14-3-3 protein and increase of ERK 1/2 and p38 MAPK activities. The 14-3-3 protein expression was positively correlated with the phosphorylation of ERK1/2. Furthermore, inhibition of the ERK1/2 with PD98059 abolished the 14-3-3 protein up-regulation in PC 12 cells induced by HPP. Conclusion HPP protects PC 12 cells against MPP＋ toxicity by up-regulating 14-3-3 protein expression through the ERK1/2 and p38 MAPK signaling pathways.

血管生成素-1对SW1116细胞的作用及其机制

目的探讨血管生成素-1(Angiopoietin-1,Ang-1)蛋白对无血清DMEM培养基培养的结肠癌细胞(SW 1116)存活率的影响及其与PI3-′k inase/Akt通路的关系。方法将不同浓度的Ang-1蛋白作用于SW 1116细胞,用MTT法检测细胞增殖,根据实验结果选定Ang-1蛋白的后续实验浓度,设计出SW 1116细胞增殖抑制模型,分别向该模型中加入Ang-1及LY294002,应用免疫印记法分析相关蛋白(Tie-2、PI3K、Akt)的变化。结果 Ang-1组与无血清DMEM培养基组比较,Tie-2、PI3K、Akt三种蛋白在SW 1116细胞中的表达均增强,但仅Tie-2的表达有显著差异(P<0.01),LY294002组三种蛋白的表达均减弱(P<0.01,P<0.05)。结论较低浓度(0.05 mg/L)的Ang-1蛋白在结肠癌细胞中即有抗凋亡作用,且随着浓度的增加抗凋亡作用逐渐加强,当高于0.2 mg/L时,作用逐渐减弱,其诱导凋亡的机制可能与Tie-2/PI3-′k inase/Akt调节的通路有关,应用该途径的抑制剂LY294002可抑制结肠癌细胞的生长,实现抗肿瘤作用。

Geniposide, the component of the Chinese herbal formula Tongluojiunao, protects amyloid-β peptide(1–42)-mediated death of hippocampal neurons via the non-classical estrogen signaling pathway

Tongluojiunao （TLJN） is an herbal medicine consisting of two main components, geniposide and ginsenoside Rg1. TLJN has been shown to protect primary cultured hippocampal neurons. How-ever, its mechanism of action remains unclear. In the present study, primary cultured hippocampal neurons treated with Aβ1-42 （10 μmol/L） signiifcantly increased the release of lactate dehydroge-nase, which was markedly reduced by TLJN （2 μL/mL）, speciifcally by the component geniposide （26 μmol/L）, but not ginsenoside Rg1 （2.5 μmol/L）. hTe estrogen receptor inhibitor, ICI182780 （1 μmol/L）, did not block TLJN-or geniposide-mediated decrease of lactate dehydrogenase under Aβ1-42-exposed conditions. However, the phosphatidyl inositol 3-kinase or mitogen-activated protein kinase pathway inhibitor, LY294002 （50 μmol/L） or U0126 （10 μmol/L）, respectively blo cked the decrease of lactate dehydrogenase mediated by TLJN or geniposide. hTerefore, these results suggest that the non-classical estrogen pathway （i.e., phosphatidyl inositol 3-kinase or mitogen-activated protein kinase） is involved in the neuroprotective effect of TLJN, speciifcally its component, geniposide, against Aβ1-42-mediated cell death in primary cultured hippocampal neurons.

PI-3 kinase pathway can mediate the effect of TGF-β1 in inducing the expression of SHARP-2 in LLC-PK1 cells

We aim to investigate the effect of transforming growth factor （TGF）-β1 on the expression of enhancer of split- and hairy-related protein-2 （SHARP-2） messenger RNA （mRNA） and its signaling pathway. In this study, several cell lines including LLC-PK1 （a porcine kidney tubular epithelial cell line）, MDCK （Madin-Darby canine kidney） and CTLL-2 （cytotoxic T-lymphocyte line） were treated with recombinant human TGF-131, and a series of experiments were carried out, involving Northern blot analysis of total RNA from these cells. Further, several specific chemical inhibitors were applied before TGF-β1 treatment to probe the signaling pathway. The results showed that TGF-β1 can significadtly up-regulate SHARP-2 mRNA expression in the LLC-PK1 cell line. The peak level of induction was found 2 h after TGF-β1 stimulation. While one phospho- inositide 3-kinases （PI-3） kinase inhibitor, LY294002, completely blocked the effect of TGF-131 on SHARP-2 mRNA expression in LLC-PK1 cells at a low concentration, other inhibitors, including PD98059, staurosporine, AG490, wortmannin, okadaic acid and rapamycin, had no effect. The effect of LY294002 was dose-dependent. We conclude that, in LLC-PK1 cells at least, TGF-β1 can effectively induce the SHARP-2 mRNA expression and that the PI-3 kinase pathway can mediate this effect.

Phototropism in land plants： Molecules and mechanism from light perception to response

BACKGROUND： Phototropism is the response a plant exhibits when it is faced with a directional blue light stimulus. Though a seemingly simple differential cell elongation response within a responding tissue that results in organ curvature, phototropism is regulated through a complex set of signal perception and transduction events that move from the plasma membrane to the nucleus. In nature phototropism is one of several plant responses that have evolved to optimize photosynthesis and growth. OBJECTIVE： In the present work we will review the state of the field with respect to the molecules and mechanisms associated with phototropism in land plants. METHODS： A systematic literature search was done to identify relevant advances in the field. Though we tried to focus on literature within the past decade （1998-present）, we have discussed and cited older literature where appropriate because of context or its significant impact to the present field. Several previous review articles are also cited where appropriate and readers should seek those out. RESULTS： A total of 199 articles are cited that fulfill the criteria listed above. CONCLUSIONS： Though important numerous and significant advances have been made in our understanding of the molecular, biochemical, cell biological and physiologic mechanisms underlying phototropism in land plants over the past decade, there are many remaining unanswered questions. The future is indeed bright for researchers in the field and we look forward to the next decade worth of discoveries.