Trop2 as an oncogene in gastric cancer by regulating PI3K/Akt signaling pathway

High Trop2 expression relates to aggressive tumor behavior and contributes to poor overall survival rates in gastric cancer (GC) patients. However, little is known about the molecular mechanism of Trop2 in the carcinogenesis of GC. We found that over-expressed Trop2 induced cell proliferation and clone formation, inhibited cell apoptosis and induced S cell cycle arrest in GC cell lines, meanwhile, knockdown Trop2 inhibited cell proliferation and clone formation, induced cell apoptosis and inhibits S cell cycle arrest in vitro. Moreover, Trop2 depletion inhibited tumor growth , the anti-tumor rate in this report being 22.53% in vivo. In addition, Trop2 activated the PI3K/Akt signaling pathway to promote GC malignant progression. These results indicated that Trop2 is a critical regulation factor in the progression of GC, which may help to lead a novel insight into understanding the mechanism of the Trop2 in the pathogenesis of GC.     

旱作农田不同耕作土壤呼吸及其对水热因子的响应

为研究旱作农田春玉米生育期不同耕作土壤呼吸变化特征及其对水热因子的响应情况,在山西省寿阳县旱农试验基地采用红外气体分析法测定了传统耕作(CT)、少耕(RT)和免耕(NT)土壤呼吸速率,并同步测定了各土层土壤水分、温度.研究表明:在春玉米生育期内,土壤呼吸速率均呈单峰型变化趋势,峰值出现在8月;传统耕作与少耕土壤呼吸速率变化趋势基本一致,而免耕土壤与前两者相比波动幅度较大;土壤呼吸峰值与水分、温度之间无明显相关,其余时期土壤呼吸与水分、温度因子具有良好的相关性;双因子模型较单因子模型能更好的描述土壤呼吸与水分、温度之间关系,基于水热双因子(10-20 cm)的指数-幂模型能够解释土壤呼吸变化的81％-87％ (P＜O.01);3种耕作土壤呼吸对水热因子协同影响的敏感性表现为CT＞NT＞RT.     

Transformation of oat and inheritance of bar gene expression

Fertile transgenic plants of oat (Avena sativa L. var. Melys) were produced following microprojectile bombardment of primary embryogenic calli from immature embryos with two plasmids containing the bar gene or the β-glucuronidase (uidA) gene, after selection with glufosinate ammonium. Eleven plants were regenerated from phosphinothricin resistant callus, with three of the eleven plants containing either intact or rearranged copies. No plants co-transformed with the non-selected uidA gene were detected. Stable transmission and expression of the bar gene in the T₁ inbred progenies occurred in a Mendelian manner in one line, which contained an intact bar gene, and in all six T₂ lines tested from this transformant. This revised version was published online in June 2006 with corrections to the Cover Date.     

Carnitine palmitoyltransferase 1A prevents fatty acid-induced adipocyte dysfunction through suppression of c-Jun N-terminal kinase

The adipocyte is the principal cell type for fat storage. CPT1 (carnitine palmitoyltransferase-1) is the rate-limiting enzyme for fatty acid β-oxidation, but the physiological role of CPT1 in adipocytes remains unclear. In the present study, we focused on the specific role of CPT1A in the normal functioning of adipocytes. Three 3T3-L1 adipocyte cell lines stably expressing hCPT1A (human CPT1A) cDNA, mouse CPT1A shRNA (short-hairpin RNA) or GFP (green fluorescent protein) were generated and the biological functions of these cell lines were characterized. Alteration in CPT1 activity, either by ectopic overexpression or pharmacological inhibition using etomoxir, did not affect adipocyte differentiation. However, overexpression of hCPT1A significantly reduced the content of intracellular NEFAs (non-esterified fatty acids) compared with the control cells when adipocytes were challenged with fatty acids. The changes were accompanied by an increase in fatty acid uptake and a decrease in fatty acid release. Interestingly, CPT1A protected against fatty acid-induced insulin resistance and expression of pro-inflammatory adipokines such as TNF-α (tumour necrosis factor-α) and IL-6 (interleukin-6) in adipocytes. Further studies demonstrated that JNK (c-Jun N terminal kinase) activity was substantially suppressed upon CPT1A overexpression, whereas knockdown or pharmacological inhibition of CPT1 caused a significant enhancement of JNK activity. The specific inhibitor of JNK SP600125 largely abolished the changes caused by the shRNA- and etomoxir-mediated decrease in CPT1 activity. Moreover, C2C12 myocytes co-cultured with adipocytes pre-treated with fatty acids displayed altered insulin sensitivity. Taken together, our findings have identified a favourable role for CPT1A in adipocytes to attenuate fatty acid-evoked insulin resistance and inflammation via suppression of JNK.     

How to map ses, a mutant of Arabidopsis thaliana affecting pollen development

In Arabidopsis, map-based cloning has been developed to an effective method in mutant genetic analysis because high-density markers are available, candidate genes or genomic sequences can be amplified by PCR, and transgenic techniques are simplified. Mutant ses named from shortened early-stage siliques was used as an example to show how to map a mutant in this way. By the process of bulked segregants analysis, linkage testing, large-scale and fine-scale mapping, mutant ses was narrowed into a 67 kb interval from CER448792 (2000541 bp) to CER464544 (2067844 bp) crossing over the right of BAC F12K11 to the left of the BAC F4H5 including at most 22 putative genes on the top of chromosome 1. In sequence-based map of Arabidopsis genes with mutant phenotype (SMAGMP) mutant ses was between AT1g06150 (EMB1444) and AT1g08060 (MOM). The ses mapping also showed that developed markers on polymorphism site of CAPC not only were simplified but worked well. Twenty-four markers from CAPC used in the mapping maybe help Arabidopsis researchs with others and the methods related to ses mapping also gave an example of positional cloning. The text was submitted by the authors in English.     

Molecular cloning and characterization of a chlorophyll degradation regulatory gene from bamboo

Leaf senescence constituted the final stage of leaf development and it is always accompanied by the leaf yellowing. The non-yellowing gene (NYE1), initially identified from Arabidopsis in our laboratory, is a key regulatory gene responsible for chlorophyll degradation during senescence. In this study, an orthologue of AtNYE1 was isolated from the bamboo (Bambusa emeiensis cv. Viridiflavus) and tentatively named BeNYE1. The full length sequence of 1 386 bp contains an open reading frame of 801 bp. The protein encoded by BeNYE1 consists of 266 amino acids. Sequence analysis revealed that BeNYE1 had high similarity with other NYE/SGR proteins from various monocotyledon species. BeNYE1 was strongly induced by natural senescence and dark-induced senescence in bamboo. Driven by a 1.5 kb upstream fragment of AtNYE1, BeNYE1 could rescue the stay-green phenotype of nye1-1. The constitutive over-expression of BeNYE1 could accelerate the chlorophyll degradation. These results indicated that BeNYE1 might play an important role in the regulation of chlorophyll degradation during leaf senescence in bamboo.     

Protein interaction data set highlighted with human Ras-MAPK/PI3K signaling pathways

The Ras-MAPK and PI3K-AKT pathways are conserved in metazoan organisms, which involve a series of signaling cascades and form the basis for numerous physiological and pathological processes. Here we report on yeast two hybrid screening results of a protein interaction network around the known components of human Ras-MAPK/PI3K pathways. A total of 42 independent cDNA library screenings resulted in 200 protein-protein interaction (PPI) pairs among 180 molecules. Most of the proteins formed a large cluster that contains 193 PPIs between 169 proteins. Seventy-four interactions indicate high-confidence according to bioinformatics analysis. The prey list contains high enrichment genes with specific Gene Ontology (GO) terms such as response to stress and response to external stimulus. Most interactions link the Ras signaling pathway with various cellular processes. Five interactions were validated by coimmunoprecipitation and colocalization assays in mammalian cells to confirm their in vivo interactions. This protein interaction network provides further insights into the molecular mechanism of Ras-MAPK/PI3K signaling pathways.     

Effects of activated ADP-ribosylation factors on Golgi morphology require neither activation of phospholipase D1 nor recruitment of coatomer

Nine mutations in the switch I and switch II regions of human ADP-ribosylation factor 3 (ARF3) were isolated from loss-of-interaction screens, using two-hybrid assays with three different effectors. We then analyzed the ability of the recombinant proteins to (i) bind guanine nucleotides, (ii) activate phospholipase D1 (PLD1), (iii) recruit coatomer (COP-I) to Golgi-enriched membranes, and (iv) expand and vesiculate Golgi in intact cells. Correlations of activities in these assays were used as a means of testing specific hypotheses of ARF action, including the role of PLD1 activation in COP-I recruitment, the role of COP-I in Golgi vesiculation caused by expression of the dominant activating mutant [Q71L]ARF3, and the need for PLD1 activation in Golgi vesiculation. Because we were able to find at least one example of a protein that has lost each of these activities with retention of the others, we conclude that activation of PLD1, recruitment of COP-I to Golgi, and vesiculation of Golgi in cells are functionally separable processes. The ability of certain mutants of ARF3 to alter Golgi morphology without changes in PLD1 activity or COP-I binding is interpreted as evidence for at least one additional, currently unidentified, effector for ARF action at the Golgi.