Project description:LMO2 is a component of multisubunit DNA-binding transcription factor complexes that regulate gene expression in hematopoietic stem and progenitor cell development. Enforced expression of LMO2 causes leukemia by inducing hematopoietic stem cell-like features in T-cell progenitor cells, but the biochemical mechanisms of LMO2 function have not been fully elucidated. In this study we systematically dissected the LMO2/LDB1 binding interface to investigate the role of this interaction in T-cell leukemia. Alanine scanning mutagenesis of the LIM interaction domain of LDB1 revealed a discrete motif R320LITR required for LMO2 binding. Most strikingly, co-expression of full length, wild type LDB1 increased LMO2 steady state abundance, whereas co-expression of mutant proteins deficient in LMO2 binding compromised LMO2 stability. These mutant LDB1 proteins also exerted dominant negative effects on growth and transcription in diverse leukemic cell lines. Raw gene expression data on HSB-2 cells is presented here. RNAseq were performed on HSB cell lines to examine their expression patterns
Project description:LMO2 is a component of multisubunit DNA-binding transcription factor complexes that regulate gene expression in hematopoietic stem and progenitor cell development. Enforced expression of LMO2 causes leukemia by inducing hematopoietic stem cell-like features in T-cell progenitor cells, but the biochemical mechanisms of LMO2 function have not been fully elucidated. In this study we systematically dissected the LMO2/LDB1 binding interface to investigate the role of this interaction in T-cell leukemia. Alanine scanning mutagenesis of the LIM interaction domain of LDB1 revealed a discrete motif R320LITR required for LMO2 binding. Most strikingly, co-expression of full length, wild type LDB1 increased LMO2 steady state abundance, whereas co-expression of mutant proteins deficient in LMO2 binding compromised LMO2 stability. These mutant LDB1 proteins also exerted dominant negative effects on growth and transcription in diverse leukemic cell lines. Raw gene expression data on HSB-2 cells is presented here.
Project description:Dr. Eric Vivier's lab would like to tackle the enzymes involved in PEN5 carbohydrate metabolism. We have generated these cell lines by repeated cell sorting and cell cloning of the parental HSB-2 T cell line and the parental JY B cell line. H+ are PEN5+ HSB-2 cells, H- are PEN5- HSB-2 cells; JY+ are PEN5+ HSB-2 cells, JY- are PEN5- HSB-2 cells. We have originally described a cell surface molecule called PEN5, as a sulfated lactosamine, that is selectively expressed on a mature subset of human NK cells (Vivier, J. Exp. Med. 1993). Later, we have shown that the PEN5 carbohydrate decorates PSGL-1, confering L-selectin binding properties (André et al. PNAS, 2000). We have recently performed a Glycan Array Screening via Core H (Glycomics 917). These studies indeed reveal a very nice binding of the anti-PEN5 mAb to a subset of sulfated lactosamines. We would like to tackle the enzymes involved in PEN5 carbohydrate metabolism. We thus requesting a Gene microarray analysis performed using RNA extracted from PEN5+ and PEN5- NK cells, as well from the H+, H-, JY+ and JY- stable cell lines. We have generated these cell lines by repeated cell sorting and cell cloning of the parental HSB-2 T cell line and the parental JY B cell line. H+ are PEN5+ HSB-2 cells, H- are PEN5- HSB-2 cells; JY+ are PEN5+ HSB-2 cells, JY- are PEN5- HSB-2 cells. RNA preparations from variants of the HSB-2 (human T leukemia) and JY (human B lymphoma) cell lines, which were express or not PEN5 were sent to Microarray Core (E). These stable variants are referred to as H+ (HSB-2 cells expressing PEN5), H- (HSB-2 cells NOT expressing PEN5), JY+ (JY cells expressing PEN5), and JY- (JY cells NOT expressing PEN5). Samples were prepared at 3 different time points. The RNA was amplified, labeled, and hybridized to the GLYCOv3 microarrays. Data was sent to Dr. Eric Vivier for analysis.
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
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
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.