Matrix metalloproteinases characterized so far are either secreted or membrane anchored via a type I transmembrane domain or a glycosylphosphatidylinositol linkage. Lacking either membrane-anchoring mechanism, the newly discovered CA-MMP/MMP-23 was reported to be expressed as a cell-associated protein. In this report, we present evidence that CA-MMP is expressed as an integral membrane zymogen with an Nterminal signal anchor, and secreted as a fully processed mature enzyme. We further demonstrate that L 20 GAALSGLCLLSALALL 36 is required for this unique membrane localization as a signal anchor and its secretion is regulated by a proprotein convertase motif RRRR 79 sandwiched between its pro-and catalytic domains. Thus, CA-MMP is a type II transmembrane MMP that can be regulated by a single proteolytic cleavage for both activation and secretion, establishing a novel paradigm for protein trafficking and processing within the secretory pathway.Proteolysis mediated by metalloproteinases has been implicated in a diverse range of biological processes such as signal transduction (1), precursor processings (2, 3), angiogenesis (4, 5), and the turnover of extracellular matrix (ECM)

Our study aimed to explore associations between microRNA-21 (miR-21) and PTEN/PI3K/AKT signaling pathway and, further, to elucidate the regulation of miR-21 on biological behaviors in human esophageal cancer cells. The expressions of miR-21, PTEN, PI3K, and AKT were detected in 89 esophageal cancer samples and 58 adjacent normal tissues respectively. The human esophageal cancer cells (TE11) were grouped as following: blank (TE11 cells without transfection), negative (TE11 cells with miR-21 negative inhibitor), and Inhibition-miR21 (TE11 cells with miR-21 inhibitor). Western blot was used for detection of PTEN, P13K, and AKT protein expressions, MTT method for cell proliferation, Transwell assay for cell migration and invasion, and flow cytometry for cell cycle and apoptosis. MiR-21, PI3K, and AKT have higher expressions, but PTEN has lower expression in esophageal cancer tissues compared with adjacent normal tissues. The esophageal cancer tissues with lymph node metastasis and poor differentiation showed significantly low positive rate of PTEN protein, but high positive rates of PI3K and AKT proteins. Compared with blank and negative groups, PTEN expression of TE11 cells in Inhibition-miR21 group was significantly up-regulated, but PI3K and AKT were down-regulated. Further, PTEN was a target gene of miR-21. Besides, compared with blank and negative groups, the proliferation, migration, and invasion of TE11 cells were less active in Inhibition-miR21 group. TE11 cells were significantly increased in the G0/G1 phase of cell cycles, but decreased in the S and G2/M phase in Inhibition-miR21 group. The TE11 cells exhibited significantly increased apoptosis rates. MiR-21 targets key proteins in PTEN/PI3K/AKT signal pathway, promoting proliferation, migration, invasion, and cell cycle, and inhibiting apoptosis of human esophageal cancer cells. It may serve as a novel therapeutic target in esophageal cancer.

Tobacco leaf discs were transformed with a plasmid, pBIPTA, containing the selectable marker neomycin phosphotransferase gene (nptII) and Pinellia ternata agglutinin gene (pta) via Agrobacterium tumefaciens-mediated transformation. Thirty-two independent transgenic tobacco plants were regenerated. PCR and Southern blot analyses confirmed that the pta gene had integrated into the plant genome and northern blot analysis revealed transgene expression at various levels in transgenic plants. Genetic analysis confirmed Mendelian segregation of the transgene in T1 progeny. Insect bioassays showed that transgenic plants expressing PTA inhibited significantly the growth of peach potato aphid (Myzus persicae Sulzer). This is the first report that transgenic plants expressing pta confer enhanced resistance to aphids. Our study indicates that the pta gene can be used as a supplement to the snowdrop (Galanthus nivalis) lectin gene (gna) in the control of aphids, a sap-sucking insect pest causing significant yield losses of crops.

No abstract

Transgenic rice plants were generated using particle bombardment to simultaneously introduce the rice Xa21 gene eective against bacterial blight and the Galanthus nivalis agglutinin (snowdrop lectin; gna) gene eective against sap-sucking insect pests, speci®cally the brown plant hopper. Using three plasmids, we cotransformed 5-to 10-d-old, mature seed-derived rice (Oryza sativa L.) callus of two elite Chinese rice cultivars, Eyi 105 and Ewan 5. The plasmids carried a total of four genes. The gna and Xa21 genes were carried on separate plasmids. The selectable marker hygromycin phosphotransferase (hpt) and the reporter gene b-glucuronidase (gusA) were linked on the same, co-integrate vector. We recovered over 160 independently derived transgenic rice plants. Over 70% of the transgenic plants carried all four genes, as con®rmed by polymerase chain reaction and/or Southern blot analysis. Furthermore, 70% of transgenic plants carrying all four genes also coexpressed all four genes, as con®rmed by growth on selection media (hpt), GUS histochemical assays (gusA), western blotting (gna) and reverse transcriptase-polymerase chain reaction (Xa21) analysis. The co-expression eciency reported for the four transgenes in our study is the highest ever found in any transgenic plant population generated through co-transformation. The linked genes (hpt and gusA) co-integrated with a frequency of near 100%, and we observed a co-integration frequency greater than 70% for the genes carried on separate plasmids. We observed no preferential integration of any particular gene(s). Genetic analysis con®rmed Mendelian segregation of the transgenes in subsequent generations. We report, for the ®rst time, generation and analysis of transgenic rice lines carrying genes eective against more than one taxa of pathogen or pest, substantiating that particle bombardment represents an eective way to introduce unlinked complex multiple traits into plants.Abbreviations: gna (GNA) = gene (protein) for Galanthus nivalis agglutinin; gusA (GUS) = gene (protein) for b-glucuronidase; hpt (HPT) = gene (protein) for hygromycin phosphotransferase; Xa21 (XA21) = gene (protein) for resistance to bacterial blight, RT-PCR = reverse transcriptase-polymerase chain reaction