Recent insights on the genetics and epigenetics of endometriosis.

Endometriosis is a gynecologic disease affecting up to 10% of the women and a major cause of pain and infertility. It is characterized by the implantation of functional endometrial tissue at ectopic positions generally within the peritoneum. This complex disease has an important genetic component with a heritability estimated at around 50%. This review aims at providing recent insights into the genetic bases of endometriosis, and presents a detailed overview of evidence of epigenetic alterations specific to this disease. In the future, these alterations may constitute therapeutic targets for pharmacological compounds able to modify the epigenetic code.

Endometriosis also affects the decidua in contact with the fetal membranes during pregnancy.

STUDY QUESTION: Are the fetal membranes of women affected with endometriosis similar to those from disease-free women? SUMMARY ANSWER: Decidua of women with endometriosis is able to generate endometriotic-like lesions in contact with the fetal membranes. WHAT IS KNOWN ALREADY: Eutopic endometrium of women affected with endometriosis presents compromised properties. Endometrium undergoes decidualisation to accept and to further control the conceptus development during pregnancy. Decidualized endometrium is in close contact with the chorionic membrane and forms the choriodecidual layer, a major maternal-fetal interface. STUDY DESIGN, SIZE, DURATION: This is a laboratory case-control study involving diseased versus control samples. Eleven case samples and 11 control samples were collected from women in a tertiary care/research center between November 2011 and December 2013. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were consecutive pregnant women affected with confirmed endometriosis and disease free women, who underwent Cesarean section before labor for obstetrical indication. The choriodecidual tissues were characterized using histology, immunohistochemistry, transcriptomic and whole genome CpG methylation analyses. MAIN RESULTS AND THE ROLE OF CHANCE: We demonstrate for the first time the presence of endometriotic-like lesions within the decidual side of the choriodecidua of the fetal membranes from women affected with severe endometriosis. Fetal membranes from women affected with endometriosis exhibited glandular components in the choriodecidual layer surrounded by enlarged decidualized cells disseminated along the entire membrane surface. Significant deregulation (variation of expression ≥2, P-value ≤0.05) was observed for 2773 genes known to be enriched in processes involved in glandular function, endocrine and nervous system, neoangiogenesis, and autoimmune disease. CpG methylation analysis revealed 5999 differentially methylated regions with a P-value ≤0.05. LIMITATIONS, REASONS FOR CAUTION: We studied women who delivered at term by Cesarean section before labor, following an uneventful pregnancy. Notwithstanding this, one cannot exclude that the presence of disseminated endometriotic lesions within the choriodecidual layer of the fetal membranes may disturb the anatomical integrity and/or the function of the membranes in some women with endometriosis. WIDER IMPLICATIONS OF THE FINDINGS: Our results shed new light on the capability of the diseased decidua to develop lesions not only at ectopic autologous locations, but also on the semi-allogenous fetal membranes, a particularly immunotolerant environment.

Impaired alveolarization and intra-uterine growth restriction in rats: a postnatal genome-wide analysis.

Intra-uterine growth restriction (IUGR) dramatically increases the risk of bronchopulmonary dysplasia in preterm babies, a disease characterized by arrested alveolarization and abnormal microvascular angiogenesis. We have previously described a rodent low protein diet (LPD) model of IUGR inducing impaired alveolarization, but failed to demonstrate any modification of the classical factors involved in lung development. We performed a genome-wide microarray analysis in 120 rat pups with LPD-induced IUGR and their controls, at three key time points of the alveolarization process: postnatal day 4 (P4): start of alveolarization; P10: peak of the alveolarization process and P21: end of the alveolarization process. Results were analysed using Arraymining, DAVID and KEGG software and validated by qRT-PCR and western blots. Considering a cut-off of 2:1 as significant, 67 transcripts at P4, 102 transcripts at P10 and 451 transcripts at P21 were up-regulated, and 89 transcripts at P4, 25 transcripts at P10 and 585 transcripts at P21 were down-regulated. Automatic functional classification identified three main modified pathways, 'cell adhesion molecules', 'cardiac muscle contraction' and 'peroxisome proliferator-activated receptor' (PPAR). Protein analysis confirmed involvement of the PPAR pathway, with an increase of FABP4, an activator of this pathway, at P4 and an increase of adiponectin at P21. Other data also suggest involvement of the PPAR pathway in impaired alveolarization. Our results show that deregulation of the PPAR pathway may be an important component of the mechanism inducing impaired alveolarization observed in IUGR. The complete dataset is available as GEO profiles on the Gene Expression Omnibus (GEO) database ( www.ncbi.nih.gov/geo/, GEO Accession No. GSE56956).

[Endometriosis-associated ovarian cancers: pathogenesis and consequences on daily practice]. / Les cancers de l'ovaire associés à l'endométriose : physiopathologie et conséquences sur la pratique clinique.

Endometriosis is considered as a tumor-like lesion under the World Health Organization (WHO) classification of ovarian tumors. Data from large cohort and case-control studies indicate that patients with a history of endometriosis have an increased risk of ovarian cancer. Recent findings suggest an association between endometriosis and the entire type 1 ovarian tumors group including clear-cell, endometrioid and low-grade serous carcinomas. However, current evidence is lacking to draw definitive conclusion whether this association represents causality or the sharing of common risk factors. Nevertheless, assumption that endometriosis could be a precursor of malignancy raises many issues about serial screening, surgical management and surveillance of endometriosis. Beyond these concerns, endometriosis-associated ovarian cancers seem to be a genuine clinical entity as regards clinicopathological features. In view of the high incidence of endometriosis (10 % of women of childbearing age), the low incidence of endometriosis-associated ovarian cancers and the psychological consequences for those women, systematic screening and surgical exploration seem very questionable in this context.

[Neurotrophins and pain in endometriosis]. / Neurotrophines et douleur: étude d'expression et de corrélation dans l'endométriose.

OBJECTIVES: To evaluate the expression of five members of the neurotrophins family in ovarian endometriotic cyst (endometrioma) (OMA), compared to eutopic endometrium (EE) and to examine the correlation between the levels of induction and the pain intensity. PATIENTS AND METHODS: Twelve Caucasian women in luteal phase, operated for painful stage IV endometriosis were assigned to 2 groups according to a total Visual Analog Scale (tVAS) score above 15 or below 10. tVAS takes into account all VAS scores for dysmenorrhea, deep dyspareunia, non cyclic chronic pelvic pain, gastrointestinal and lower urinary symptoms. Samples of OMA and EE were processed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) for NGF, BDNF, NT-3, NT-4/5 and NTRK2 mRNA expression. Expression levels in OMA were compared to those in EE on one hand and between two groups of 6 mild painful and 6 highly painful patients on the other. RESULTS: All neurotrophins were significantly higher expressed in OMA than in EE, in particular NGF and BDNF (induction ratios: 20.6 and 9.7, respectively). In contrast, no correlation was observed between induction ratios and pain intensity. CONCLUSION AND DISCUSSION: This is the first study reporting an over-expression of all neurotrophins in endometriosis, as only NGF was previously documented. It confirms the central role of this family in the genesis and modulation of pain in endometriosis. Anti-neurotrophin selective therapy might be a promising way of analgesia in the future.

[Endometriosis and genetics: what responsibility for the genes?]. / Endométriose et génétique : les gènes sont-ils responsables de la maladie ?

Endometriosis is a very frequent and debilitating disease responsible for a considerable socio-economic toll. In spite of that, its pathogenesis remains enigmatic. Endometriosis is hold for a multifactorial pathology resulting from the mixed effects of environmental and genetic factors. To date, few susceptibility factors have been reported, with the exception of some polymorphisms in estrogen and progesterone receptors. Large-scale expressional studies have clearly demonstrated that endometriosis is a hormone-dependant disease, characterized by three main features: (i) inflammation, (ii) excessive production of estrogens, and (iii) progesterone resistance. Endometriosis is also considered as a benign metastatic disease, closely linked to cancer. However, the risk of malignant transformation appears to be very limited, likely by a systematic repression of the genes involved in cell cycle and a specific regulation of the HOX genes. Lastly, endometriosis might result from abnormalities of the eutopic endometrium, which show the same molecular alterations than the ectopic endometrium, to a lesser extent however. These alterations, possibly occurring during the embryonic life through epigenetic and genetic predisposition, could lead to an earlier and non-invasive diagnosis for endometriosis.

Cullins in human intra-uterine growth restriction: expressional and epigenetic alterations.

Intra-uterine growth restriction (IUGR) is defined by a restriction of fetal growth during gestation. It is a prevalent significant public health problem that jeopardizes neonatal health but also that can have deleterious consequences later in adult life. Cullins constitute a family of seven proteins involved in cell scaffold and in selective proteolysis via the ubiquitin-proteasome system. Most Cullins are critical for early embryonic development and mutations in some Cullin genes have been identified in human syndromes including growth retardation. Our work hypothesis is that Cullins, particularly CUL4B and CUL7, are involved in placental diseases and especially in IUGR. Thus, expression of Cullins and their cofactors was analyzed in normal and pathological placentas. We show that they present a constant significant over-expression in IUGR placentas, whose extent is dependent on the position of the interrogated fragment along the cDNAs, suggesting the existence of different isoforms of the genes. Particularly, the CUL7 gene is up-regulated up to 10 times in IUGR and 15 times in preeclampsia associated with IUGR. The expression of cofactors of Cullins participating to functional complexes has also been evaluated and showed a similar significant increase in IUGR. Promoters of Cullin genes appeared to be under the control of the SP1 transcription factor. Finally, methylation levels of the CUL7 promoter in placental tissues are modulated according to the pathological conditions, with a significant hypomethylation in IUGR. These results concur to pinpoint the Cullin family as a new set of markers of IUGR.

A 12 000-rad whole-genome radiation hybrid panel in sheep: application to the study of the ovine chromosome 18 region containing a QTL for scrapie susceptibility.

Whole-genome radiation hybrid (RH) panels have been constructed for several species, including cattle. RH panels have proven to be an extremely powerful tool to construct high-density maps, which is an essential step in the identification of genes controlling important traits, and they can be used to establish high-resolution comparative maps. Although bovine RH panels can be used with ovine markers to construct sheep RH maps based on bovine genome organization, only some (c. 50%) of the markers available in sheep can be successfully mapped in the bovine genome. So, with the development of genomics and genome sequencing projects, there is a need for a high-resolution RH panel in sheep to map ovine markers. Consequently, we have constructed a 12 000-rad ovine whole-genome RH panel. Two hundred and eight hybrid clones were produced, of which 90 were selected based on their retention frequency. The final panel had an average marker retention frequency of 31.8%. The resolution of this 12 000-rad panel (SheepRH) was estimated by constructing an RH framework map for a 23-Mb region of sheep chromosome 18 (OAR18) that contains a QTL for scrapie susceptibility.

Characterization, genetic variation and chromosomal assignment to sheep chromosome 2 of the ovine heart fatty acid-binding protein gene (FABP3).

The purpose of this study was to locate and detect genetic variation in the sheep FABP3 gene, a candidate gene for milk and meat quality traits in sheep. We have obtained an almost complete sequence (4,689 bp, excluding a part of intron 1) of the sheep FABP3 gene using PCR-based comparative genome walking. Sheep FABP3 has been located to chromosome 2 by sheep sequence-specific PCR on DNA from a sheep/rodent cell hybrid panel, and confirmed by linkage mapping using the International Mapping Flock. Direct sequencing of PCR products amplified from different DNA samples of Manchega breed sheep over the complete sheep FABP3 gene revealed 13 SNPs, one CTC insertion/deletion and a variable polyA tract. This poly A tract was found in association with a SINE/artiodactyls repeat. In addition, two SNPs were screened in different sheep breeds.

Comparative gene mapping: a fine-scale survey of chromosome rearrangements between ruminants and humans.

A total of 202 genes were cytogenetically mapped to goat chromosomes, multiplying by five the total number of regional gene localizations in domestic ruminants (255). This map encompasses 249 and 173 common anchor loci regularly spaced along human and murine chromosomes, respectively, which makes it possible to perform a genome-wide comparison between three mammalian orders. Twice as many rearrangements as revealed by ZOO-FISH were observed. The average size of conserved fragments could be estimated at 27 and 8 cM with humans and mice, respectively. The position of evolutionary breakpoints often correspond with human chromosome sites known to be vulnerable to rearrangement in neoplasia. Furthermore, 75 microsatellite markers, 30 of which were isolated from gene-containing bacterial artificial chromosomes (BACs), were added to the previous goat genetic map, achieving 88% genome coverage. Finally, 124 microsatellites were cytogenetically mapped, which made it possible to physically anchor and orient all the linkage groups. We believe that this comprehensive map will speed up positional cloning projects in domestic ruminants and clarify some aspects of mammalian chromosomal evolution.

Comparative linkage mapping of human chromosome 13 and bovine chromosome 12.

A comparative linkage map of human chromosome 13 and bovine chromosome 12 was constructed using eight polymorphic microsatellite markers associated with six specific genes. Linkage of these was also examined relative to five previously mapped anonymous microsatellite markers. Seven gene-linked markers were developed from bovine large-insert genomic clones containing one of five genes of interest (serotonin receptor subtype 2, fms-related tyrosine kinase, coagulation factor 10, retinoblastoma susceptibility gene, collagen type IV alpha 1), and one additional marker was developed from a microsatellite resident within an intron of the bovine dopachrome tautomerase gene. Four of these loci were previously assigned to bovine chromosome 12 by analysis of a somatic cell hybrid panel. This study provides linkage information for examining gene order in this conserved synteny group. The comparative linkage mapping results indicate that the q arm of human chromosome 13 is almost entirely conserved in bovine chromosome 12. One intrachromosomal rearrangement was detected in this linkage group relative to human, and this rearrangement was confirmed by fluorescence in situ hybridization results.

Evolutionary conservation of a microsatellite in the Wilms tumour (WT) gene: mapping in sheep and cattle.

A microsatellite in the WT (Wilms tumour) gene is shown to be evolutionarily conserved in a range of mammals. The microsatellite was monomorphic in pig and two alleles have been found in goat. In cattle, a one-base size polymorphism has been discovered outside the microsatellite. WT was genetically mapped to bovine chromosome 15 and to sheep chromosome 15 by synteny mapping. Conservation of chromosome segments of HSA11 and BTA15 is discussed.

Protein binding to the interferon response enhancer correlates with interferon induction of 2'-5'-oligoadenylate synthetase in normal and interferon-resistant Friend cells.

The induction of transcription of the 2'-5'-oligoadenylate (2-5A) synthetase gene by type I (alpha/beta) and type II (gamma) interferons (IFNs) has been studied in wild-type (w.t.) and IFN-resistant Friend leukemia cells (FLC). Following IFN treatment, new complexes are formed in vitro between the IFN-responsive sequence (IRS) of the 2-5A synthetase gene and cellular proteins. Within minutes after IFN-alpha/beta addition to w.t. FLC, an IRS-protein complex, designated F1, is detected, as already observed in several human cell lines. In response to IFN-gamma, a novel complex, designated Fg, is observed in w.t. FLC. The Fg complex appears within 3 h, while an F1-like complex is faintly visible 10 to 24 h later. In the IFN-alpha/beta-resistant FLC, IFN-gamma induces only the Fg complex and fails to induce F1. Fg formation is correlated with the IFN-gamma-induced transcription of the 2-5A synthetase gene and the appearance of the corresponding enzymatic activity in both w.t. and IFN-alpha/beta-resistant FLC. These findings suggest that F1 and Fg represent two distinct effector complexes by which type I and type II IFNs, respectively, induce 2-5A synthetase.

Interleukin-6 induces the (2'-5') oligoadenylate synthetase gene in M1 cells through an effect on the interferon-responsive enhancer.

Interleukin-6 (IL-6) activates (2'-5') A synthetase (2'-5' AS) gene expression in differentiating myeloleukemic M1 cells. Antibodies to type I interferon (IFN) inhibit 2'-5' AS induction but not differentiation. Analysis of the mechanism of 2'-5' AS induction shows that it does not result from increased IFN formation, but from a synergism between IL-6 and endogenously secreted IFN. IL-6 can activate expression of a CAT construct fused to the interferon response sequence (IRS) of the 2'-5' AS gene. In extracts of IL-6-treated M1 cells, changes in protein binding to IRS DNA can be demonstrated. One of the effects of IL-6 on M1 cells is, therefore, to induce DNA binding factors, some of which act on the same enhancer sequence as IFNs, resulting in a synergistic gene activation. M1 variants resistant to differentiation by IL-6 have lost the ability to induce the 2'-5' AS gene.

Enhancer functions and in vitro protein binding of native and mutated interferon-responsive sequences.

Mutants of the Interferon responsive sequence (IRS) of the mouse and human (2'-5') A synthetase (moE-IRS and hE-IRS) were tested for their Interferon (IFN)-inducible enhancer functions and for protein binding in vitro. Two complexes R1 and R3, were formed specifically with the hE-IRS. R3 migrated much faster and was about ten times more abundant than R1. R1 and R3 are increased about 2-fold in IFN-treated HeLa extracts relatively to extracts from non-treated cells. R1 and R3 seem to involve the same DNA sequence in the probe since they react identically to competitors. Two proteins of 69 and 46 kDa form the IRS specific complexes as revealed by UV cross-linking. Identical DNA probes bearing either the hE-IRS or moE-IRS form complexes of different characteristics with nuclear proteins, suggesting that the two IRS variants are the targets of binding of different proteins or of different protein complexes.