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Genome-Wide Mapping of 5-mC and 5-hmC in severely Preeclamptic Placentas.

ABSTRACT: Preeclampsia (PE) is a major contributor of maternal mortality with uncertain etiology. Recent studies suggested that epigenetic modifications, including DNA methylation, play a vital role in the development of PE. In this study, we have mapped genome-wide distribution of 5-methylcytosin (5-mC) and 5-hydroxymethylcytosine (5-hmC) using MeDIP and (h)MeDIP in the placentas from severely preeclamptic patients and normal controls. A total 194485 pooled 5-mC peaks and 138133 pooled 5-hmC peaks were identified, of which 714 5-mC peaks and 119 5-hmC peaks showed significant difference between patients and controls (>2-fold, p<0.05).To our knowledge, this is the first report of DHMRs (Differentially Hydroxy-Methylated Regions) in preeclamptic placenta. We not only confirmed the aberrant DNA methylated regions in the process of preeclampsia reported previously, but also identified unreported regions. A total of 4 selected DMRs (Differentially Methylated Regions) were also confirmed by MassARRAY EppiTYPER. Of these, PTPRN2, which had low level of 5-mC and high level of 5-hmC at gene body, was further verified to have lower methylation level at promoter regions in case group compared with controls. In conclusion, our study provided genome-wide distribution of 5-mC and 5-hmC in severe PE and normal controls, which have further clinical value for the identification of diagnostic and therapeutic markers for severe PE.

ORGANISM(S): Homo sapiens

PROVIDER: GSE63743 | GEO | 2014/12/13

SECONDARY ACCESSION(S): PRJNA268963

REPOSITORIES: GEO

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Project description:DNA methylation (5-mC) and hydroxymethylation (5-hmC) are regarded as important epigenetic hallmarks in the carcinogenesis of colorectal cancer by transcriptional regulation. 5hmC is an intermediate during active demethylation and maintains the equilibrium of DNA methylation. Previous studies on DNA methylation don’t differentiate 5-hmC from 5-mC. Here, in order to elucidate the epigenetic mechanisms of carcinogenesis of colorectal cancer, we integrate genome wide levels of 5-mC, 5-hmC and Transcriptional expression. 12 samples, including six colorectal tumor tissues and corresponding normal colonic tissues were recruited after surgery. Genome-wide DNA methylation was determined by methylated DNA immune- precipitation sequencing (MeDIP-seq), and hydroxymethylation by hydroxyl- methylated DNA immune-precipitation sequencing (hMedip-seq). Transcriptional expression was determined by RNA-seq. Group-wise different methylation region (DMR), different hydroxyl methylation region (DhMR) and different expressed gene (DEG) were identified. Epigenetic biomarkers were screened by integrating DMR, DhMR and DEG. We found that a genome-scale distinct hydroxymethylation pattern could be used as epigenetic biomarker for clearly differentiating colorectal cancer from normal tissues. 59249 differentially methylated regions (DMR), 187172 differentially hydroxymethylated region (DhMR) and 948 differentially expressed genes (DEGs) were identified. After cross-matched genes containing DMRs or DhMRs with DEGs, seven genes were screened. Furthermore, hypermethylation of HADHB was persistently found to be correlated with its down-regulation of transcription in CRC, potentially suggesting its role as TSG. The differences of methylation, hydroxymethylation and transcriptional expression in HADHB between cancerous and normal tissues were validated among additional colorectal cancer patients. To further validate this assumption, we also performed functional analysis and found that the expression of HADHB obviously reduced cancer cells migration and invasiveness. This study provided valuable basic data for screening epigenetic biomarkers and elucidated the epigenetic mechanisms of carcinogenesis of colorectal cancer.

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Genome-Wide Mapping of 5-mC and 5-hmC in severely Preeclamptic Placentas.

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