Project description:Only very few studies have investigated methylation patterns of different types of hydatidiform moles (HMs). Methylation patterns of androgenetic HMs (AnHMs) are abnormal due to the fact that the nuclear genome in AnHMs is inherited from the father, only. Diploid biparental HMs (BiHM) have been suggested to display the same methylation patterns of imprinted genes as AnHMs, and the methylation patterns are suspected to be a consequence of a failure to establish maternal methylation at multiple genome-wide loci. We have investigated the methylation patterns of AnHMs, BiHM-like placentas with a chr. 11p15.5 deletion and a BiHM from a woman with NLRP7 mutations and compared these to methylation patterns of normal placentas. Using the Next Generation Sequencing (NGS) technique Reduced Representation Bisulfite Sequencing (RRBS) we instigated the genome-wide CpG methylation of 32 samples, including nine normal placentas, 20 androgenetic diploid HMs (AnHMs), and three diploid biparental HMs/HM-like placentas. This dataset contains RRBS data from 12 samples, including the nine normal placentas and the three diploid biparental HMs/HM-like placentas.The RRBS data from 20 androgenetic diploid HMs (AnHMs) was deposited in GSE65881:http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE65881
Project description:Imprinted genes are critical for normal human growth and neurodevelopment. We developed a strategy to identify new DNA differentially methylated regions (DMRs), a hallmark of imprinted genes. Using genome-wide methylation profiling, candidate DMRs were selected by identifying CpGs with putative allelic differential methylation in normal biparental tissues. In parallel, we looked for parent of origin-specific DNA methylation patterns in paternally derived human androgenetic complete hydatidiform mole (AnCHM), and maternally derived mature cystic ovarian teratoma (MCT). Using this approach, we found known DMRs associated with imprinted genomic regions as well as new DMRs for known imprinted genes, NAP1L5 and ZNF597. Most importantly, novel candidate imprinted genes were identified. The paternally methylated DMR for one candidate, AXL, a receptor tyrosine kinase, was validated by methylation analyses in humans. Further validation in mouse embryos showed that Axl was expressed preferentially from the maternal allele in a DNA methylation–dependent manner. We have analyzed 3 androgenetic complete hydatidiform mole (AnCHM), 16 white blood cell (WBC), 1 mature cystic ovarian teratoma (MCT), 5 placenta, and 1 lymphoblastoid cell line paternal UPD4 sample
Project description:Imprinted genes are critical for normal human growth and neurodevelopment. We developed a strategy to identify new DNA differentially methylated regions (DMRs), a hallmark of imprinted genes. Using genome-wide methylation profiling, candidate DMRs were selected by identifying CpGs with putative allelic differential methylation in normal biparental tissues. In parallel, we looked for parent of origin-specific DNA methylation patterns in paternally derived human androgenetic complete hydatidiform mole (AnCHM), and maternally derived mature cystic ovarian teratoma (MCT). Using this approach, we found known DMRs associated with imprinted genomic regions as well as new DMRs for known imprinted genes, NAP1L5 and ZNF597. Most importantly, novel candidate imprinted genes were identified. The paternally methylated DMR for one candidate, AXL, a receptor tyrosine kinase, was validated by methylation analyses in humans. Further validation in mouse embryos showed that Axl was expressed preferentially from the maternal allele in a DNA methylation–dependent manner.
Project description:Genomic imprinting is a form of epigenetic regulation that results in expression of either the maternally or paternally inherited allele of a subset of genes. Imprinted loci contain differentially methylated regions (DMRs) where cytosine methylation marks one of the parental alleles, providing cis-acting regulatory elements that influence the allelic expression of surrounding genes, however to date the total number of imprinted loci within the human genome is unknown. To characterize known imprinted DMRS and identify novel imprinted loci we have performed whole-genome bisulphite sequencing and high-resolution DNA methylation array analysis of healthy tissues. Sequencing of bisulfite converted DNA and array based analysis of normal tissues, human embryonic stem cells, androgenetic hydatidiform moles and leukocytes from reciprocal genome-wide uniparental disomies.
Project description:Heterozygous CHMs have been believed as synonymous with dispermic moles (two sperm origin). The possibility of diploid sperm origin has not been considered. We assessed whether heterozygous CHMs would be of dispermic or diploid sperm origin. In all the cases, centromeric zygosity was random, i.e., mixed status. Theoretically, if the heterozygous CHMs were of diploid sperm origin, the centromeric status will be all homozygous or all heterozygous. Thus, all the analyzed heterozygous CHMs were considered to be of dispermic origin. Three cases showed the trisomy while we did not notice them with STR analysis. Diploid sperm fertilization can be rare during the development of heterozygous androgenetic CHM.
Project description:The first mitotic division causes both parental genomes present in the zygote to segregate into two biparental diploid daughter cells. This fundamental tenet was challenged by the observation that blastomeres with different genome ploidy and distinct parental genotypes can coexist within individual embryos. We hypothesized that whole parental genomes can segregate into distinct blastomere lines during the multipolar division of the zygote, a phenomenon referred to as “heterogoneic” cell division. Here, we provide evidence of genome-wide segregation errors in two human blastocysts and further pinpoint its origin in a bovine model by mapping the genomic landscape of 82 blastomeres from 25 embryos that underwent multipolar division at the zygote stage using genome-wide SNP arrays and sequencing. In most embryos, the coexistence of androgenetic and diploid or polyploid blastomeres with or without anuclear blastomeres, androgenetic and anuclear blastomeres, and androgenetic and gynogenetic blastomeres within the same embryo provided proof that multipolar zygotic division coincides with heterogoneic segregation of the parental genome. By mapping the segregational origin of the genomic content, we deduced distinct segregation mechanisms underlying heterogoneic cell division including segregation by a tripolar spindle, the pronuclear extrusion of a paternal genome and, the operation of an ectopic paternal or private parental spindles. Polyspermic embryos expel excessive paternal genomes resulting in an androgenetic or polyploid blastomere. Confirming the results in human blastocysts we found genome-wide segregation errors to persist in bovine blastocysts.
Project description:Maternal-effect mutations in components of the subcortical maternal complex (SCMC) of the human oocyte can cause early embryonic failure, gestational abnormalities and recurrent pregnancy loss. Enigmatically, they are also associated with DNA methylation abnormalities at imprinted genes in conceptuses, in the devastating gestational abnormality biparental complete hydatidiform mole (BiCHM) or in multi-locus imprinting disease (MLID). However, the developmental timing, genomic extent and mechanistic basis of these imprinting defects are unknown. Here, we studied methylation level of a women reported with familial recurrent hydatidiform mole and multiple pregnancy loss. Genotype analysis revealed homozygous mutation in KHDC3L. We obtained biparental mole from patient (Patient D) and compared it’s whole-genome methylation profile with respect to control placentas and sporadic mole (AnCHM) using Infinium MethylationEPIC BeadChip (WG-317-1001, Illumina). We also used endometrium samples from their respective mother for the comparison purposes. Molar conceptuses were observed with methylation defects at genome-wide level and profound loss of methylation at multiple genome-derived differentially methylated regions (gDMRs) confirming MLID.
Project description:Androgenetic induced pluripotent stem cells (AgHiPSCs) were generated from androgenetic fibroblasts derived from a complete hydatidiform mole. AgHiPSCs can be used in regenerative medicine, for analysis of genomic imprinting, to study imprinting-related development, and for disease modeling in humans. To investigate the pluripotency state of AgHiPSCs, we analyzed their cellular and molecular characteristics (morphology, RT-PCR, qPCR, immunochemistry, and differentiation capacity in vitro and in vivo). We tested the DNA methylation status of imprinted genes using bisulfite sequencing and demonstrated the androgenetic identity of AgHiPSCs.
Project description:Genomic imprinting is a mechanism in which the expression of genes varies depending on their parent-of-origin. Imprinting occurs through differential DNA methylation and histone modifications on the two parental alleles, with most imprinted genes marked by CpG-rich differentially methylated regions (DMRs). DNA methylation profiling in cases of uniparental disomy (UPD) provides a unique system permitting the study of DNA derived from a single parent (PMID: 20631049). Approximately 70 human imprinted genes have been described, and imprinted loci have been associated with diseases such as diabetes and cancer. We profiled parent of origin DNA methylation marks to find novel imprinted loci. Methods: We have an unprecedented collection of whole blood DNA from XX patients with UPD covering 18 different chromosomes, allowing for the efficient detection of DMRs associated with imprinted genes for 84% of the human genome. Our study is complimented with Ovarian Teratoma DNA (maternal DNA) and Complete hydatidiform Mole (paternal DNA). DNA methylation was profiled using Illumina Infinium 450K Methylation BeadArrays. Imprinted DMRs were defined by sites at which the maternal and paternal methylation levels diverged significantly from the biparental average. We confirmed novel DMRs by bisulfite sequencing of informative trios and SequenomEpiTYPER assays. Allelic specific gene expression studies were also performed by RNA sequencing in independent biparental controls. Findings: Our results provide for the first comprehensive map of the human imprintome, doubling the number of known imprinted regions. We identified a total of 71 DMRs, 41 of which were novel. 27 novel DMRs were maternally methylated and 14 were paternally methylated. We identified DMRs on chromosomes 5, 21 and 22 previously considered devoid of imprinting, highlighting potential parent-of-origin effects in chromosomal aneuploidies such as Down syndrome. We also found DMRs in genes associated with Schizophrenia and epilepsy. Interpretation: Our data provide the first comprehensive genome-wide map of imprinted sites in the human genome, and provide novel insights into potential parent-of-origin effects in human disorders. 66 UPD samples analyzed in total, From each individual, whole bllod DNA was extracted and global DNA methylation levels were assessed using Illumina Infinium HumanMethylation450 BeadChip.