Expression of BLIMP1/PRMT5 and concurrent histone H2A/H4 arginine 3 dimethylation in fetal germ cells, CIS/IGCNU and germ cell tumors

<p>Background: Most testicular germ cell tumors arise from intratubular germ cell neoplasia unclassified (IGCNU, also referred to as carcinoma in situ), which is thought to originate from a transformed primordial germ cell (PGC)/gonocyte, the fetal germ cell. Analyses of the molecular profile of IGCNU and seminoma show similarities to the expression profile of fetal germ cells/gonocytes. In murine PGCs, expression and interaction of Blimp1 and Prmt5 results in arginine 3 dimethylation of histone H2A and H4. This imposes epigenetic modifications leading to transcriptional repression in mouse PGCs enabling them to escape the somatic differentiation program during migration, while expressing markers of pluripotency.</p><p>Results: In the present study, we show that BLIMP1 and PRMT5 were expressed and arginine dimethylation of histones H2A and H4 was detected in human male gonocytes at weeks 12–19 of gestation, indicating a role of this mechanism in human fetal germ cell development as well. Moreover, BLIMP1/PRMT5 and histone H2A and H4 arginine 3 dimethylation was present in IGCNU and most seminomas, while downregulated in embryonal carcinoma (EC) and other nonseminomatous tumors. </p><p>Conclusion: These data reveal similarities in marker expression and histone modification between murine and human PGCs. Moreover, we speculate that the histone H2A and H4 arginine 3 dimethylation might be the mechanism by which IGCNU and seminoma maintain the undifferentiated state while loss of these histone modifications leads to somatic differentiation observed in nonseminomatous tumors.</p

Critical Function of AP-2gamma/TCFAP2C in Mouse Embryonic Germ Cell Maintenance

<p>Formation of the germ cell lineage involves multiple processes, including repression of somatic differentiation and reacquisition of pluripotency as well as a unique epigenetic constitution. The transcriptional regulator Prdm1 has been identified as a main coordinator of this process, controlling epigenetic modification and gene expression. Here we report on the expression pattern of the transcription factor Tcfap2c, a putative downstream target of Prdm1, during normal mouse embryogenesis and the consequences of its specific loss in primordial germ cells (PGCs) and their derivatives. Tcfap2c is expressed in PGCs from Embryonic Day 7.25 (E 7.25) up to E 12.5, and targeted disruption resulted in sterile animals, both male and female. In the mutant animals, PGCs were specified but were lost around E8.0. PGCs generated in vitro from embryonic stem cells lacking TCFAP2C displayed induction of Prdm1 and Dppa3. Upregulation of Hoxa1, Hoxb1, and T together with lack of expression of germ cell markers such Nanos3, Dazl, and Mutyh suggested that the somatic gene program is induced in TCFAP2C-deficient PGCs. Repression of TCFAP2C in TCam-2, a human PGCresembling seminoma cell line, resulted in specific upregulation of HOXA1, HOXB1, MYOD1, and HAND1, indicative of mesodermal differentiation. Expression of genes indicative of ectodermal, endodermal, or extraembryonic differentiation, as well as the finding of no change to epigenetic modifications, suggested control by other factors. Our results implicate Tcfap2c as an important effector of Prdm1 activity that is required for PGC maintenance, most likely mediating Prdm1-induced suppression of mesodermal differentiation.</p

Additional file 1: Table S1. of Disorders of sex development: insights from targeted gene sequencing of a large international patient cohort

DSD gene variants. Each variant found in a diagnostic gene (after the filtering and curation process) is shown. In some cases where the gene is inherited in an autosomal recessive manner, two variants are grouped together. Inheritance has been indicated where familial samples were available: negative indicates negative for variant and N/A sample not available. De novo events have only been noted where both parental samples were available and found to be negative for the change. Previously reported refers to a variant being described in either ClinVar, HGMD, or a publication in a peer-reviewed journal via a PubMed search. Variants were classified consistent with previous MPS publications of DSD cohorts [8, 10] which were based on ACMG guidelines [15]. VUS were called for three reasons: 1 = fits phenotype but predicted to be benign; 2 = damaging but doesn’t fit phenotype; or 3 = variant in the AR repetitive region. Patients marked with an asterisk were identified to have two or more diagnostic gene variants. Null variants (frameshifts, splice sites mutations, and premature stop codons) are shown in bold. Patients have been classified based on clinical notes provided, according to the recommended classification of DSD in the Chicago consensus report. Classifications: CGD complete gonadal dysgenesis, DASA disorders of androgen synthesis or action, DSD DSD of “unknown” origin; hypospadias, LCH Leydig cell hypoplasia, OT ovotesticular DSD, PGD partial gonadal dysgenesis, PMDS persistent Müllerian duct syndrome; syndromic, T testicular DSD. Related affected individuals are indicated. File is in Excel spreadsheet format. (XLSX 47 kb