Project description:The role of somatic mitochondrial DNA (mtDNA) mutations in leukemogenesis remains poorly characterized. To determine the impact of somatic mtDNA mutations on the process, we assessed the leukemogenic potential of hematopoietic progenitor cells (HPCs) from mtDNA mutator mice (Polg D257A) with or without NMyc overexpression. We observed a higher incidence of spontaneous leukemogenesis in recipients transplanted with heterozygous Polg HPCs and a lower incidence of NMyc-driven leukemia in those with homozygous Polg HPCs compared to controls. Although mtDNA mutations in heterozygous and homozygous HPCs caused similar baseline impairments in mitochondrial function, only heterozygous HPCs responded to and supported altered metabolic demands associated with NMyc overexpression. Homozygous HPCs showed altered glucose utilization with pyruvate dehydrogenase inhibition due to increased phosphorylation, exacerbated by NMyc overexpression. The impaired growth of NMyc-expressing homozygous HPCs was partially rescued by inhibiting pyruvate dehydrogenase kinase, highlighting a relationship between mtDNA mutation burden and metabolic plasticity in leukemogenesis.
Project description:The purpose of this data set was to identify the affects of somatic cell introduction of the methylation results of the sperm samples. This data was then used to help build a computational tool to properly identify somatic cell contamination within a sperm sample.
Project description:The potential that adolescent chemotherapy can impact the epigenetic programming of the germ line to influence later life adult fertility and promote epigenetic inheritance was investigated. Adult males approximately ten years after pubertal exposure to chemotherapy were compared to adult males with no previous exposure. Sperm were collected to examine differential DNA methylation regions (DMR) between the exposed and control populations. A statistically significant signature of DMRs was identified in the chemotherapy exposed male sperm. The DMRs, termed epimutations, were found in CpG desert regions of primarily 1 kilobase size. Gene associations and correlations to genetic mutations (copy number variation) were also investigated. Observations indicate adolescent chemotherapy exposure can promote epigenetic alterations that persist in later life. The germline (i.e. sperm) epimutations identified suggest chemotherapy has the potential to promote epigenetic inheritance to the next generation.
Project description:To establish contamination profiles, the sperm donors with normal sperm counts were analyzed using an Infinium HumanMethylation450 array. Somatic cell lysis, sperm isolation, DNA extraction, and bisulfite conversion were performed as described by Aston et al. The bisulfite converted sperm DNA was hybridized to Illumina Infinium HumanMethylation450K microarrays at the University of Utah and run as recommended by the manufacturer (Bibikova et al. 2011). Unpaired blood samples were extracted using Qiagen's DNeasy Blood and Tissue kit and bisulfite converted using Zymo's EZ DNA Methylation kit. All procedures were performed according to the instructions of the manufacturer. Four permutations were run on each sample, including pure blood, half blood and half sperm by DNA concentration, half blood and half sperm by cell count, and pure sperm (n = 16). Concentration was normalized using a spectrophotometer. A Makler cell counting chamber was used to count white blood cells and sperm, which were then normalized in a 1:1 ratio.
Project description:In human sperm, preserved histones evading histone-to-protamine replacement were observed in certain genes and gene promoters, but also in distal intergenic and repetitive DNA regions. The substantiality of the latter and its putative biological role are still a subject of hot debate. To shed more light on this issue we analyzed H4K20me3, a histone mark regulating heterochromatic and repetitive DNA in somatic cells, which was recently detected in human sperm. Our immunohistochemical and western blot analyses revealed the presence of H4K20me3 in male germ cells at every stage of spermatogenesis and in mature sperms, respectively. By ChIP-sequencing of the motile sperm fractions from three biological replicates we found 4.56% of the sperm genome to be occupied by H4K20me3. By comparing the genome-wide binding sites of H4K20me3 in sperm cells and somatic cells (K562) we found correspondences in 77% of respective peaks. The majority of binding sites (70%) were detected in distal intergenic and intron regions. Intriguingly, H4K20me3 enrichments could be observed in both somatic and sperm cells within satellite repeats and retrotransposons, particularly in long interspersed nuclear repeats (LINEs) and retrotransposons containing long terminal repeats (LTR-retrotransposons). Broad cluster arrangements and strong enrichments in olfactory receptor genes were also characteristic for H4K20me3. This is the first time H4K20me3 is characterized at the genome-wide level in human sperm and compared to somatic cells. Our results reveal that H4K20me3 constitutes the majority of histones preserved in matured human sperm and maintains a somatic-like distribution pattern.