Metformin promotes survivin degradation through AMPK/PKA/GSK-3β-axis in non–small cell lung cancer

Metformin, a first-line antidiabetic drug, has been reported with anticancer activities in many types of cancer. However, its molecular mechanisms remain largely unknown. As a member of inhibitor of apoptosis proteins, survivin plays an important role in the regulation of cell death. In the present study, we investigated the role of survivin in metformin-induced anticancer activity in non–small cell lung cancer in vitro. Metformin mainly induced apoptotic cell death in A549 and H460 cell lines. It remarkably suppressed the expression of survivin, decreased the stability of this protein, then promoted its proteasomal degradation. Moreover, metformin greatly suppressed protein kinase A (PKA) activity and induced its downstream glycogen synthase kinase 3β (GSK-3β) activation. PKA activators, both 8-Br-cAMP and forskolin, significantly increased the expression of survivin. Consistently both GSK-3β inhibitor LiCl and siRNA restored the expression of survivin in lung cancer cells. Furthermore, metformin induced adenosine 5′-monophosphate-activated protein kinase (AMPK) activation. Suppression of the activity of AMPK with Compound C reversed the degradation of survivin induced by metformin, and meanwhile, restored the activity of PKA and GSK-3β. These results suggest that metformin kills lung cancer cells through AMPK/PKA/GSK-3β-axis–mediated survivin degradation, providing novel insights into the anticancer effects of metformin.     

Highly efficient genome editing using oocyte-specific zcas9 transgenic zebrafish

正Since its first application to induce mutations in mammalian cells (Cong et al., 2013; Mali et al., 2013), CRISPR/Cas9 has rapidly become a routine technique to perform genome editing in a variety of biological systems due to its facile, robust, and multiplexable features (Hwang et al., 2013; Wang et al., 2013; Guo et al., 2014; Liu,     

Control of Foodborne Pathogens during Sufu Fermentation and Aging

ABSTRACT:?

Referee: Dr. Catharina Y. W. Ang, National Center Toxicology Research, HFT-230, FDA, 3900 NCTR Road, Jefferson, AR 72079

Control of the foodborne pathogens Escherichia coli O157:H7, Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes during sufu fermentation was evaluated. Before fermentation, pathogens were inoculated onto tofu (substrate for sufu) at 5 log cfu/g or 3 log cfu/g, and starter culture (Actinomucor elegans) was inoculated at 3 log cfu/g. After 2 days of fermentation at 30°C, the four pathogens reached 7 to 9 log cfu/g, and the mold count reached 6 to 7 log cfu/g. After fermentation, sufu samples were aged in a solution of 10% alcohol + 12% NaCl. After 1 month of aging, the total bacterial count was 6 to 7 log cfu/g, but all foodborne pathogens and mold were reduced to nondetectable levels. The total bacterial count decreased after aging for 2 months and 3 months, but the differences were not significant (P>0.05) compared with the count after 1 month. Microorganism in experimental sufu from different aging periods and in commercial sufu were compared. A total of 270 isolates were purified and identified by the BBL Crystal Identification System. From the experimental sufu samples, 49 Bacillus spp. (20.4%), 167 Enterococcus spp. (69.6%), 6 Shewanella putrefaciens (2.4%), and 18 miscellaneous Gram-negative bacilli (7.5%) were identified. From commercial sufu samples, 17 Bacillus. spp. (56.7%), 2 Enterococcus durans (6.7%), 5 miscellaneous Gram-negative bacilli (16.7%), 5 Corynbacterium aquaticum (16.7%), and 1 Shewanella putrefaciens (3.3%) were obtained. Although the longer aging period did not significantly decrease the total bacterial count, it may help in the development of sufu flavor. This study showed that sufu fermentation and aging can control common foodborne pathogens, so sufu is a safe product even though its preparation does not include pasteurization.     

Interactions between fungal growth, substrate utilization and enzyme production during shallow stationary cultivation of Phanerochaete chrysosporium on cotton stalks

Microbial pretreatment of lignocellulosic feedstocks is an environment friendly alternative to physio-chemical pretreatment methods. A better understanding of the interactive fungal mechanisms in biological systems is essential for enhancing performance and facilitating scale-up and commercialization of this pretreatment technique. In this study, mathematical models were developed for describing cellulose and hemicellulose consumption, lignin degradation, cellulase and ligninolytic enzyme production and oxygen uptake associated with the growth of Phanerochaete chrysosporium during a 14-day shallow stationary submerged fungal pretreatment process on cotton stalks. Model parameters were estimated and validated by Statistics Toolbox in MatLab 7.1. Models yielded sufficiently accurate predictions for cellulose and hemicellulose consumption (R2=0.9772 and 0.9837), lignin degradation (R2=0.9879 and 0.8682) and ligninolytic enzyme production (R2=0. 8135 and 0.9693) under both 1-day and 3-day oxygen flushing conditions, respectively. The predictabilities for fungal growth (R2=0.6397 and 0.5750) and cellulase production (R2=0.0307 and 0.3046) for 1-day and 3-day oxygen flushing, respectively, and oxygen uptake (R2=0.5435) for 3-day oxygen flushing were limited.     

蛋白激酶Ca相互作用蛋白的结构与功能

蛋白激酶Cα相互作用蛋白(proteininteractingwithCαkinase,PICK1)是蛋白激酶Cα(proteinkinaseCα,PKCα)的靶蛋白之一,也是在PKCα和突触后膜受体蛋白间起重要作用的衔接蛋白。PICK1分别由PDZ结构域、BAR结构域以及卷曲螺旋区和酸性氨基酸区组成。PICK1中的PDZ结构域和受体蛋白、转运蛋白、衔接蛋白的相互作用报道较多,BAR结构域则与支架蛋白、质膜等相互作用。PICK1在突触可塑性、神经递质传递、外周神经感觉、细胞生长和黏连等方面发挥重要作用。本文对PICK1的结构和功能进行综述。     

杂环肽FIK的Fmoc固相合成法研究

为研究二硫键成环的杂环肽FIK的合成工艺, 以Fmoc氨基酸为原料, 采用固相合成法, 经TBTU/HOBT/DIEA复合缩合剂催化合成直链肽, 再经I2氧化肽链上两个半胱氨酸的巯基生成分子内二硫键而得到目标环肽, 将其用切割试剂切割脱离树脂得到粗产品, MALDI-MS和RP-HPLC进行鉴定, 分析和纯化。产率可以达到18%, 纯化后纯度达97%以上, 经MALDI-MS和Ellman试剂检测确定为目标肽。该合成法高效, 简便, 快速, 目标肽收到较理想产率, 适合大批量生产。