Project description:The human A-family DNA polymerase M-NM-8 (Pol q) is a large, multidomain enzyme whose physiological function is still unclear despite its in vitro translesion synthesis capacity in front of DNA damage and its involvement in some features of DNA repair after external stress. Here we present evidence that Pol q holds a novel role in the absence of external stress as a critical determinant of the replication timing program in human cells. Pol q binds to chromatin at early G1 and is required for proper formation of pre-replicative complexe and replication origin activation. Pol q-depleted cells show modified spatial organization of chromatin-loop structures at replication factories. Genome-wide analysis of replication timing shows delayed replication of a part of early replicating domains and advanced replication of a part of late replicating domains following Pol q depletion. Our results identify Pol q as one of the first critical human factors discovered in the replication timing programme. Two-condition experiment, siRNA control vs. siRNA polQ cells. Biological replicates: 2 control replicates, 2 transfected replicates.
Project description:The human A-family DNA polymerase M-NM-8 (Pol q) is a large, multidomain enzyme whose physiological function is still unclear despite its in vitro translesion synthesis capacity in front of DNA damage and its involvement in some features of DNA repair after external stress. Here we present evidence that Pol q holds a novel role in the absence of external stress as a critical determinant of the replication timing program in human cells. Pol q binds to chromatin at early G1 and is required for proper formation of pre-replicative complexe and replication origin activation. Pol q-depleted cells show modified spatial organization of chromatin-loop structures at replication factories. Genome-wide analysis of replication timing shows delayed replication of a part of early replicating domains and advanced replication of a part of late replicating domains following Pol q depletion. Our results identify Pol q as one of the first critical human factors discovered in the replication timing programme. Two-condition experiment, control vs. over expressed polQ cells. Biological replicates: 2 control replicates, 2 transfected replicates.
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.
Project description:In multicellular organisms, developmental changes to replication timing occur in 400- 800 kb domains across half the genome. While clear examples of epigenetic control of replication timing have been described, a role for DNA sequence in mammalian replication timing has not been substantiated. To assess the role of DNA sequences in directing these changes, we profiled replication timing in mice carrying a genetically rearranged Human Chromosome 21 [Hsa21]. In two distinct mouse cell types, Hsa21 sequences maintained human-specific replication timing, except at points of Hsa21 rearrangement. Changes in replication timing at rearrangements extended up to 900 kb and consistently reconciled with the wild-type replication pattern at developmental boundaries of replication-timing domains. Our results demonstrate DNA sequencedriven regulation of Hsa21 replication timing during development and provide evidence that mammalian chromosomes consist of multiple independent units of replication timing regulation. Profile comparison of fibroblast and T-cell cultures from trans-chromosomic mice and human and mouse controls.