Project description:Dyskeratosis congenita (DKC) and idiopathic aplastic anemia (AA) are bone marrow failure syndromes that share characteristics of premature aging with severe telomere attrition. In this study, we analyzed blood samples of 62 AA and 13 DKC patients to demonstrate that their epigenetic age predictions are overall increased, albeit not directly correlated with telomere length. Aberrant DNA methylation was observed in the gene PRDM8 in DKC and AA as well as in other diseases with premature aging phenotype, such as Down syndrome, Werner syndrome and Hutchinson-Gilford-Progeria syndrome. To gain further insight into the functional relevance of PRDM8 we generated induced pluripotent stem cells (iPSCs) with heterozygous and homozygous knockout. Loss of PRDM8 impaired hematopoietic and neuronal differentiation of iPSCs, but it did not impact on epigenetic age. Taken together, aberrant DNA methylation in PRDM8 provides a biomarker for bone marrow failure syndromes, which may contribute to the hematopoietic and neuronal phenotypes of premature aging syndromes.
Project description:Dyskeratosis congenita (DKC) and idiopathic aplastic anemia (AA) are bone marrow failure syndromes that share characteristics of premature aging with severe telomere attrition. In this study, we analyzed blood samples of 62 AA and 13 DKC patients to demonstrate that their epigenetic age predictions are overall increased, albeit not directly correlated with telomere length. Aberrant DNA methylation was observed in the gene PRDM8 in DKC and AA as well as in other diseases with premature aging phenotype, such as Down syndrome, Werner syndrome and Hutchinson-Gilford-Progeria syndrome. To gain further insight into the functional relevance of PRDM8 we generated induced pluripotent stem cells (iPSCs) with heterozygous and homozygous knockout. Loss of PRDM8 impaired hematopoietic and neuronal differentiation of iPSCs, but it did not impact on epigenetic age. Taken together, aberrant DNA methylation in PRDM8 provides a biomarker for bone marrow failure syndromes, which may contribute to the hematopoietic and neuronal phenotypes of premature aging syndromes.
Project description:Gene methylation profiling of immortalized human mesenchymal stem cells comparing HPV E6/E7-transfected MSCs cells with human telomerase reverse transcriptase (hTERT)- and HPV E6/E7-transfected MSCs. hTERT may increase gene methylation in MSCs. Goal was to determine the effects of different transfected genes on global gene methylation in MSCs.
Project description:PARN deficiency is linked to the inherited disease Dyskeratosis Congenita and Familial Pulmonary Fibrosis. The aim of this experiment is to identify miRNAs that are regulated by PARN in human cells, deficiency of which could explain the disease phenotype in patients.
Project description:Dyskerin is a pseudouridine synthase involved in fundamental cellular processes (including rRNA and snRNA modification and telomere stabilization), whose function is altered in X-linked dyskeratosis congenita and cancer. Dyskerin role in ribosome processing was suggested to underlie the alterations in mRNA translation described in cells lacking dyskerin function. We compared the protein contents of 5 replicates of ribosomal preparations from control or dyskerin-depleted human cells.
Project description:Gene methylation profiling of immortalized human mesenchymal stem cells comparing HPV E6/E7-transfected MSCs cells with human telomerase reverse transcriptase (hTERT)- and HPV E6/E7-transfected MSCs. hTERT may increase gene methylation in MSCs. Goal was to determine the effects of different transfected genes on global gene methylation in MSCs. Two-condition experiment, KP MSCs vs. 3A6 MSCs.
Project description:Dyskeratosis congenita (DKC) is characterized by impaired telomere maintenance and reveals clinical features of premature aging. So far, diagnosis of DKC relies particularly on telomere length screening raising the need for additional biomarkers. In this study, we analysed global DNA methylation (DNAm) profiles of DKC patients. Age-associated DNAm changes were not generally accelerated in DKC. However, we observed significant hypermethylation in the gene for PR domain containing 8 (PRDM8). Notably, the same genomic region revealed hypermethylation in aplastic anemia (AA), and Down syndrome (DS), indicating that there might be an association with premature aging syndromes. Site-specific analysis of DNAm level in PRDM8 with pyrosequencing and MassArray validated aberrant hypermethylation in 14 DKC patients and 27 AA patients. Notably, telomere length was not directly correlated with DNAm in PRDM8, indicating that the two methods are complementary. In conclusion, DNAm at PRDM8 provides a new biomarker to support diagnosis of of AA and DKC.
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:SPO11-promoted DNA double-strand breaks (DSBs) formation is a crucial step for meiotic recombination, and it is indispensable to detect the broken DNA ends accurately for dissecting the molecular mechanisms behind. Here, we report a novel technique, named DEtail-seq (DNA End tailing followed by sequencing), that can directly and quantitatively capture the meiotic DSB 3’ overhang hotspots at single-nucleotide resolution.