Project description:Analysis of contribution of cell type of origin and individual to gene expression differences in iPSCs. The hypothesis tested in the present study was that cell type of origin affects iPSC gene expression. Results show that individual has a much stronger effect than cell type of origin on differences between iPSCs derived from multiple individuals.
Project description:Analysis of contribution of cell type of origin and individual to gene expression differences in iPSCs. The hypothesis tested in the present study was that cell type of origin affects iPSC gene expression. Results show that individual has a much stronger effect than cell type of origin on differences between iPSCs derived from multiple individuals.
Project description:Analysis of contribution of cell type of origin and individual to gene expression differences in iPSCs. The hypothesis tested in the present study was that cell type of origin affects iPSC gene expression. Results show that individual has a much stronger effect than cell type of origin on differences between iPSCs derived from multiple individuals. DNA obtained from feeder-free iPSCs derived from multiple individuals and tissues and their corresponding cell type of origin
Project description:Analysis of contribution of cell type of origin and individual to gene expression differences in iPSCs. The hypothesis tested in the present study was that cell type of origin affects iPSC gene expression. Results show that individual has a much stronger effect than cell type of origin on differences between iPSCs derived from multiple individuals. Total RNA obtained from feeder-free iPSCs derived from multiple individuals and tissues and their corresponding cell type of origin
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:The equivalency of human induced pluripotent stem cells (hiPSCs) with human embryonic stem cells (hESCs) remains controversial. Here, we devised a strategy to assess the contribution of clonal growth, reprogramming method and genetic background to transcriptional patterns in hESCs and hiPSCs. Surprisingly, transcriptional variation originating from two different genetic backgrounds was dominant over variation due to the reprogramming method or cell type of origin of pluripotent cell lines. Moreover, the few differences we detected between isogenic hESCs and hiPSCs neither predicted functional outcome, nor distinguished an independently derived, larger set of unmatched hESC/hiPSC lines. We conclude that hESCs and hiPSCs are transcriptionally and functionally highly similar and cannot be distinguished by a consistent gene expression signature. Our data further imply that genetic background variation is a major confounding factor for transcriptional comparisons of pluripotent cell lines, explaining some of the previously observed expression differences between unmatched hESCs and hiPSCs. Expression profiling of human embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and fibroblasts, mostly in triplicates.
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