Cloning and functional characterization of a cDNA encoding isopentenyl diphosphate isomerase involved in taxol biosynthesis in Taxus media / 药学学报

Taxol is one of the most potent anti-cancer agents, which is extracted from the plants of Taxus species. Isopentenyl diphosphate isomerase (IPI) catalyzes the reversible transformation between IPP and DMAPP, both of which are the general 5-carbon precursors for taxol biosynthesis. In the present study, a new gene encoding IPI was cloned from Taxus media (namely TmIPI with the GenBank Accession Number KP970677) for the first time. The full-length cDNA of TmIPI was 1 232 bps encoding a polypeptide with 233 amino acids, in which the conserved domain Nudix was found. Bioinformatic analysis indicated that the sequence of TmIPI was highly similar to those of other plant IPI proteins, and the phylogenetic analysis showed that there were two clades of plant IPI proteins, including IPIs of angiosperm plants and IPIs of gymnosperm plants. TmIPI belonged to the clade of gymnosperm plant IPIs, and this was consistent with the fact that Taxus media is a plant species of gymnosperm. Southern blotting analysis demonstrated that there was a gene family of IPI in Taxus media. Finally, functional verification was applied to identify the function of TmIPI. The results showed that biosynthesis of β-carotenoid was enhanced by overexpressing TmIPI in the engineered E. coli strain, and this suggested that TmIPI might be a key gene involved in isoprenoid/terpenoid biosynthesis.

A novel chloroplastic isopentenyl diphosphate isomerase gene from Jatropha curcas: Cloning, characterization and subcellular localization

Background Jatropha curcas is a rich reservoir of pharmaceutically active terpenoids. More than 25 terpenoids have been isolated from this plant, and their activities are anti-bacterial, anti-fungal, anti-cancer, insecticidal, rodenticidal, cytotoxic and molluscicidal. But not much is known about the pathway involved in the biosynthesis of terpenoids. The present investigation describes the cloning, characterization and subcellular localization of isopentenyl diphosphate isomerase (IPI) gene from J. curcas. IPI is one of the rate limiting enzymes in the biosynthesis of terpenoids, catalyzing the crucial interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Results A full-length JcIPI cDNA consisting of 1355 bp was cloned. It encoded a protein of 305 amino acids. Analysis of deduced amino acid sequence predicted the presence of conserved active sites, metal binding sites and the NUDIX motif, which were consistent with other IPIs. Phylogenetic analysis indicated a significant evolutionary relatedness with Ricinus communis. Southern blot analysis showed the presence of an IPI multigene family in J. curcas. Comparative expression analysis of tissue specific JcIPI demonstrated the highest transcript level in flowers. Abiotic factors could induce the expression of JcIPI. Subcellular distribution showed that JcIPI was localized in chloroplasts. Conclusion This is the first report of cloning and characterization of IPI from J. curcas. Our study will be of significant interest to understanding the regulatory role of IPI in the biosynthesis of terpenoids, although its function still needs further confirmation.

Effect of Ech1 overexpression on biological behavior of mouse hepatocarcinoma Hca-P cells in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effect of enoyl coenzyme A hydratase-1 (Ech1) on the proliferation and invasion ability of mouse hepatocarcinoma Hca-P cells in vitro.</p><p><b>METHODS</b>Recombinant pcDNA3.1(+)-Ech1 gene and pcDNA3.1(+) were transfected into Hca-P cells by cationic liposomes introduction. Clone of PEch1 cells that stably expressing Ech1 and clone of control Pvector cells were screened by G418. The Ech1 expression was identified subsequently by reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. The malignant behaviors of the cell lines were compared by proliferation, invasion and migration test.</p><p><b>RESULTS</b>The cell line Hca-P cells stably expressing Ech1 gene was constructed. The relative expression of Ech1 mRNA in the PEch1 group was 3.21 ± 0.43 and in the Pvector group was 1.44 ± 0.03, with a significant difference between the two groups (P = 0.029). The results of ELISA revealed that the expression of Ech1 protein was 0.140 ± 0.005 in the PEch1 group, 0.088 ± 0.003 in the Pvector group, and 0.078 ± 0.006 in the Hca-P group, showing a significant difference between the PEch1 group and the Pvector and Hca-P groups (P < 0.05). Transwell migration test showed that the number of penetrated cells in the PEch1 group was 143.00 ± 7.25 cells, significantly higher than that of the Pvector group (95.73 ± 3.88 cells) and un-treated Hca-1 group (106.67 ± 3.54 cells, both P < 0.05). The Transwell invasion assay showed that the number of penetrated cells was 77.20 ± 5.46 cells in the PEch1 group, significantly higher than 46.34 ± 4.35 cells in the Pvector group and 49.80 ± 5.21 cells in the un-treated Hca-1 group (both P < 0.05).</p><p><b>CONCLUSIONS</b>The results showed that overexpressed Ech1 in Hca-P cells may significantly increase the cell proliferation in a time-dependent manner. The up-regulation of Ech1 may increase to some extent the migration and invasion capacity of Hca-P cells. The efforts aiming at up-regulation of Ech1 expression may become a therapeutic target in the treatment of hepatocarcinoma.</p>

Down-regulation of Ech1 decreases the adhesion ability of mouse hepatocarcinoma Hca-F cells / 中华肝脏病杂志

To examine the differential expression pattern of Ech1 protein in mouse Hca-F and Hca-P hepatocarcinoma cell lines with high and low rates of lymphatic metastasis, respectively, and to investigate the relationships between Ech1 expression and adhesion of Hca-F cells. Fluorescence two-dimensional difference in-gel electrophoresis (2D DIGE) and mass spectrometry were used to detect Ech1 expression. Ech1 gene silencing was achieved by stable transfection of Hca-F cells with a plasmid vector harboring short hairpin RNA (shRNA) targeting Ech1, pGPU6/GFP/Neo-shRNA-Ech1. Ech1 mRNA and protein expressions were detected by real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting analysis, respectively. Adhesive properties of cells were assessed by hematoxylin-eosin staining and fluorimetric detection of extracellular matrix (ECM) proteins. Endogenous Ech1 protein level was remarkably higher in the highly metastatic Hca-F cell line than in the Hca-P cell line (2.7-fold by 2D DIGE; 1.5-fold by Western blotting). shRNA-induced silencing of Ech1 significantly reduced the adhesion ability of Hca-F cells, as evidenced by decreased absorbance values of fibronectin and collagen I (Hca-F cells vs. pGPU6/GFP/Neo-shRNA-Ech1 cells: 1.42+/-0.26 vs. 1.01+/-0.27 and 1.14+/-0.07 vs. 0.90+/-0.09, respectively; P less than 0.05). Down-regulation of Ech1 can inhibit the adhesive capacity of metastatic Hca-F cells.