Susanne Bens

DNA Methylation Analysis in Nonalcoholic Fatty Liver Disease Suggests Distinct Disease-Specific and Remodeling Signatures after Bariatric Surgery

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder in industrialized countries. Liver samples from morbidly obese patients (n = 45) with all stages of NAFLD and controls (n = 18) were analyzed by array-based DNA methylation and mRNA expression profiling. NAFLD-specific expression and methylation differences were seen for nine genes coding for key enzymes in intermediate metabolism (including PC, ACLY, and PLCG1) and insulin/insulin-like signaling (including IGF1, IGFBP2, and PRKCE) and replicated by bisulfite pyrosequening (independent n = 39). Transcription factor binding sites at NAFLD-specific CpG sites were >1,000-fold enriched for ZNF274, PGC1A, and SREBP2. Intraindividual comparison of liver biopsies before and after bariatric surgery showed NAFLD-associated methylation changes to be partially reversible. Postbariatric and NAFLD-specific methylation signatures were clearly distinct both in gene ontology and transcription factor binding site analyses, with >400-fold enrichment of NRF1, HSF1, and ESRRA sites. Our findings provide an example of treatment-induced epigenetic organ remodeling in humans.

Atypical Teratoid/Rhabdoid Tumors Are Comprised of Three Epigenetic Subgroups with Distinct Enhancer Landscapes

Atypical teratoid/rhabdoid tumor (ATRT) is one of the most common brain tumors in infants. Although the prognosis of ATRT patients is poor, some patients respond favorably to current treatments, suggesting molecular inter-tumor heterogeneity. To investigate this further, we genetically and epigenetically analyzed 192 ATRTs. Three distinct molecular subgroups of ATRTs, associated with differences in demographics, tumor location, and type of SMARCB1 alterations, were identified. Whole-genome DNA and RNA sequencing found no recurrent mutations in addition to SMARCB1 that would explain the differences between subgroups. Whole-genome bisulfite sequencing and H3K27Ac chromatin-immunoprecipitation sequencing of primary tumors, however, revealed clear differences, leading to the identification of subgroup-specific regulatory networks and potential therapeutic targets.

Poorly differentiated chordoma with SMARCB1/INI1 loss: a distinct molecular entity with dismal prognosis

Martin Hasselblatt1 · Christian Thomas1 · Volker Hovestadt2,3 · Daniel Schrimpf3,4,5 · Pascal Johann3,6,7 · Susanne Bens8 · Florian Oyen9 · Susanne Peetz‐Dienhart1 · Yvonne Crede1 · Annika Wefers3,4,5 · Hannes Vogel10 · Markus J. Riemenschneider11 · Manila Antonelli12,13 · Felice Giangaspero12,13 · Marie Christine Bernardo14 · Caterina Giannini15 · Nasir Ud Din16 · Arie Perry17 · Kathy Keyvani18 · Frank van Landeghem19 · David Sumerauer20 · Peter Hauser21 · David Capper3,4,5 · Andrey Korshunov3,4,5 · David T. W. Jones3,6 · Stefan M. Pfister3,6,7 · Reinhard Schneppenheim9 · Reiner Siebert8 · Michael C. Frühwald22 · Marcel Kool3,6

Recurrent loss of heterozygosity in 1p36 associated with TNFRSF14 mutations in IRF4 translocation negative pediatric follicular lymphomas

Pediatric follicular lymphoma is a rare disease that differs genetically and clinically from its adult counterpart. With the exception of pediatric follicular lymphoma with IRF4-translocation, the genetic events associated with these lymphomas have not yet been defined. We applied array-comparative genomic hybridization and molecular inversion probe assay analyses to formalin-fixed paraffin-embedded tissues from 18 patients aged 18 years and under with IRF4 translocation negative follicular lymphoma. All evaluable cases lacked t(14;18). Only 6 of 16 evaluable cases displayed chromosomal imbalances with gains or amplifications of 6pter-p24.3 (including IRF4) and deletion and copy number neutral-loss of heterozygosity in 1p36 (including TNFRSF14) being most frequent. Sequencing of TNFRSF14 located in the minimal region of loss in 1p36.32 showed nine mutations in 7 cases from our series. Two subsets of pediatric follicular lymphoma were delineated according to the presence of molecular alterations, one with genomic aberrations associated with higher grade and/or diffuse large B-cell lymphoma component and more widespread disease, and another one lacking genetic alterations associated with more limited disease.

Array-based DNA methylation profiling in male infertility reveals allele-specific DNA methylation in PIWIL1 and PIWIL2

OBJECTIVE To identify CpG sites differentially methylated in peripheral blood of men with idiopathic infertility due to impaired spermatogenesis as compared with fertile controls. DESIGN DNA methylation profiling on peripheral blood samples using the HumanMethylation450 BeadChip (Illumina) in patients and controls, single-nucleotide polymorphism (SNP) typing by Sanger sequencing. SETTING University institute in cooperation with genetic and infertility clinics. PATIENT(S) 30 infertile men with normal CFTR and AZF tests and karyotype, and 10 fertile male controls. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) DNA methylation levels at CpG sites. RESULT(S) We identified 471 CpGs (287 genes) as differentially methylated between patients and controls. These were significantly enriched for the gene ontology functions MHC class II receptor activity and piwi-interacting (piRNA) binding. The latter was associated with two methylation-sensitive SNPs in the genes PIWIL1 and PIWIL2, respectively, which showed significant allele distribution skewing in the infertile cohort. We found that 445 (94.5%) of 471 differentially methylated CpGs were associated with SNPs, but 26 (15 genes) were not genomically templated, including the ENO1, MTA2, BRSK2, and LBX2 genes previously associated with fertility and spermatogenesis. CONCLUSION(S) Our study identifies surrogate DNA methylation markers for idiopathic infertility in peripheral blood and suggests that allele-specific DNA methylation differences at regulatory sites of genes involved in piRNA regulation are associated with disturbed spermatogenesis.

Androgen receptor function links human sexual dimorphism to DNA methylation.

Sex differences are well known to be determinants of development, health and disease. Epigenetic mechanisms are also known to differ between men and women through X-inactivation in females. We hypothesized that epigenetic sex differences may also result from sex hormone functions, in particular from long-lasting androgen programming. We aimed at investigating whether inactivation of the androgen receptor, the key regulator of normal male sex development, is associated with differences of the patterns of DNA methylation marks in genital tissues. To this end, we performed large scale array-based analysis of gene methylation profiles on genomic DNA from labioscrotal skin fibroblasts of 8 males and 26 individuals with androgen insensitivity syndrome (AIS) due to inactivating androgen receptor gene mutations. By this approach we identified differential methylation of 167 CpG loci representing 162 unique human genes. These were significantly enriched for androgen target genes and low CpG content promoter genes. Additional 75 genes showed a significant increase of heterogeneity of methylation in AIS compared to a high homogeneity in normal male controls. Our data show that normal and aberrant androgen receptor function is associated with distinct patterns of DNA-methylation marks in genital tissues. These findings support the concept that transcription factor binding to the DNA has an impact on the shape of the DNA methylome. These data which derived from a rare human model suggest that androgen programming of methylation marks contributes to sexual dimorphism in the human which might have considerable impact on the manifestation of sex-associated phenotypes and diseases.

DNA-Methylation Profiling of Fetal Tissues Reveals Marked Epigenetic Differences between Chorionic and Amniotic Samples

Epigenetic mechanisms including DNA methylation are supposed to play a key role in fetal development. Here we have investigated fetal DNA-methylation levels of 27,578 CpG loci in 47 chorionic villi (CVS) and 16 amniotic cell (AC) samples. Methylation levels differed significantly between karyotypically normal AC and CVS for 2,014 genes. AC showed more extreme DNA-methylation levels of these genes than CVS and the differentially methylated genes are significantly enriched for processes characteristic for the different cell types sampled. Furthermore, we identified 404 genes differentially methylated in CVS with trisomy 21. These genes were significantly enriched for high CG dinucleotid (CpG) content and developmental processes associated with Down syndrome. Our study points to major tissue-specific differences of fetal DNA-methylation and gives rise to the hypothesis that part of the Down syndrome phenotype is epigenetically programmed in the first trimester of pregnancy.

Congenital Lipoid Adrenal Hyperplasia: Functional Characterization of Three Novel Mutations in the STAR Gene

CONTEXT The steroidogenic acute regulatory protein (StAR) has been shown to be essential for steroidogenesis by mediating cholesterol transfer into mitochondria. Inactivating StAR mutations cause the typical clinical picture of congenital lipoid adrenal hyperplasia. OBJECTIVE The objective of the investigation was to study the functional and structural consequences of three novel StAR mutations (p.N148K in an Italian patient; p.P129fs and p.Q128R in a Turkish patient). METHODS AND RESULTS Transient in vitro expression of the mutant proteins together with P450 side-chain cleavage enzyme, adrenodoxin, and adrenodoxin reductase yielded severely diminished cholesterol conversion of the p.N148K mutant, the combined p.P129fs and p.Q128R mutant, and the p.P129fs mutant by itself. The p.Q128R mutant led to a higher cholesterol conversion than the wild-type StAR protein. As derived from three-dimensional protein modeling, the residue N148 is lining the ligand cavity of StAR. A positively charged lysine residue at position 148 disturbs the hydrophobic cluster formed by the alpha4-helix and the sterol binding pocket. The frame shift mutation p.P129fs truncates the StAR protein. Residue p.Q128 is situated at the surface of the molecule and is not part of any functionally characterized region of the protein. CONCLUSION The mutations p.N148K and p.P129fs cause adrenal insufficiency in both cases and lead to a disorder of sex development with complete sex reversal in the 46, XY case. The mutation p.Q128R, which is not relevant for the patients phenotype, is the first reported variant showing a gain of function. We speculate that the substitution of hydrophilic glutamine with basic arginine at the surface of the molecule may accelerate cholesterol transfer.

Array-based DNA methylation analysis in individuals with developmental delay/intellectual disability and normal molecular karyotype.

Despite recent progress in molecular karyotyping and clinical sequencing the cause of intellectual disability in a considerable subset of individuals affected by this phenotype remains elusive. As intellectual disability is also a feature of various imprinting disorders and some monogenic forms of intellectual disability are caused by epigenetic modifiers we hypothesized that changes in DNA methylation might be associated with or even causative in some cases of intellectual disability. Therefore, we performed a DNA methylation analysis of peripheral blood samples from 82 patients with intellectual disability and additional features using the HumanMethylation450 BeadChip. The findings were compared to that of 19 normal controls. Differentially methylated loci were validated by bisulfite pyrosequencing. On a global level, we failed to detect a robust DNA methylation signature segregating individuals with intellectual disability from controls. Using an individual approach, we identified 157 regions showing individual DNA methylation changes in at least one patient. These correlated to 107 genes including genes linked to conditions associated with intellectual disability, namely COLEC11, SHANK2, GLI2 and KCNQ2, as well as imprinted genes like FAM50B and MEG3. The latter was suggestive of an undiagnosed Temple syndrome which could be confirmed by diagnostic tests. Subsequent in-depth analysis of imprinted loci revealed DNA methylation changes at additional imprinted loci, i.e. PPIEL, IGF2R, MEG8 and MCTS2/HM13, in up to five patients. Our findings indicate that imprinting disorders are rare but probably under-diagnosed in patients with intellectual disability and moreover point to DNA methylation changes as potential alternative means to identify deregulated genes involved in the pathogenesis of intellectual disability.

A familial disorder of altered DNA-methylation

Background In a subset of imprinting disorders caused by epimutations, multiple imprinted loci are affected. Familial occurrence of multilocus imprinting disorders is rare. Purpose/objective We have investigated the clinical and molecular features of a familial DNA-methylation disorder. Methods Tissues of affected individuals and blood samples of family members were investigated by conventional and molecular karyotyping. Sanger sequencing and RT-PCR of imprinting-associated genes (NLRP2, NLRP7, ZFP57, KHDC3L, DNMT1o), exome sequencing and locus-specific, array-based and genome-wide technologies to determine DNA-methylation were performed. Results In three offspring of a healthy couple, we observed prenatal onset of severe growth retardation and dysmorphism associated with altered DNA-methylation at paternally and maternally imprinted loci. Array-based analyses in various tissues of the offspring identified the DNA-methylation of 2.1% of the genes in the genome to be recurrently altered. Despite significant enrichment of imprinted genes (OR 9.49), altered DNA-methylation predominately (90.2%) affected genes not known to be imprinted. Sequencing of genes known to cause comparable conditions and exome sequencing in affected individuals and their ancestors did not unambiguously point to a causative gene. Conclusions The family presented herein suggests the existence of a familial disorder of DNA-methylation affecting imprinted but also not imprinted gene loci potentially caused by a maternal effect mutation in a hitherto not identified gene.