Project description:The Human T-cell Leukemia Virus (HTLV)-type-I non-structural protein p30 plays an important role in virus transmission and gene regulation. p30 has been documented to inhibit the export of certain viral mRNA transcripts from the nucleus to the cytoplasm. This nuclear retainment of RNA molecules essentially results in gene silencing, where protein products are not produced. Considering this unique function of p30, we used microarray analysis to assess the ability of p30 to inhibit not only the regulation of transcription of cellular genes, but also the ability of p30 to regulate the export of cellular transcripts to the cytoplasm. Experiment Overall Design: Total or cytoplamsic RNA from peripheral blood mononuclear cells expressing HTLV-I p30 was isolated and analyzed by microarray analysis, in comparison with mock-transcuced cells.
Project description:The Human T-cell Leukemia Virus (HTLV)-type-I non-structural protein p30 plays an important role in virus transmission and gene regulation. p30 has been documented to inhibit the export of certain viral mRNA transcripts from the nucleus to the cytoplasm. This nuclear retainment of RNA molecules essentially results in gene silencing, where protein products are not produced. Considering this unique function of p30, we used microarray analysis to assess the ability of p30 to inhibit not only the regulation of transcription of cellular genes, but also the ability of p30 to regulate the export of cellular transcripts to the cytoplasm.
Project description:Here, by combining transcriptome and proteome profiling, we identified 228 post-transcriptionally regulated genes with strict regulation at the protein level in PSCs. Among them, 84 genes were found necessary for the survival of several cell types including PSCs, and 20 genes were identified as specific for the survival of PSCs. These 20 proteins were upregulated only in PSCs and not in differentiated cells derived from the three germ layers. Subcellular fractionation of the mRNA showed that the expression level of most of the 20 proteins was regulated at the mRNA localization stage from the nucleus to the cytoplasm in PSCs, but their translation efficiency was unchanged compared with other cell types. Together, these results reveal a critical function of post-transcriptionally regulated genes on PSC survival.
Project description:Comparing the gene expression profiling of HDGF-silenced RD-ES cells and control RD-ES cells to identify genes regulated by HDGF in RD-ES cells. Keywords: expression analysis
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes