Triin Laisk

Research Resource: Interactome of Human Embryo Implantation: Identification of Gene Expression Pathways, Regulation, and Integrated Regulatory Networks

A prerequisite for successful embryo implantation is adequate preparation of receptive endometrium and the establishment and maintenance of a viable embryo. The success of implantation further relies upon a two-way dialogue between the embryo and uterus. However, molecular bases of these preimplantation and implantation processes in humans are not well known. We performed genome expression analyses of human embryos (n = 128) and human endometria (n = 8). We integrated these data with protein-protein interactions in order to identify molecular networks within the endometrium and the embryo, and potential embryo-endometrium interactions at the time of implantation. For that, we applied a novel network profiling algorithm HyperModules, which combines topological module identification and functional enrichment analysis. We found a major wave of transcriptional down-regulation in preimplantation embryos. In receptive-stage endometrium, several genes and signaling pathways were identified, including JAK-STAT signaling and inflammatory pathways. The main curated embryo-endometrium interaction network highlighted the importance of cell adhesion molecules in the implantation process. We also identified cytokine-cytokine receptor interactions involved in implantation, where osteopontin (SPP1), leukemia inhibitory factor (LIF) and leptin (LEP) pathways were intertwining. Further, we identified a number of novel players in human embryo-endometrium interactions, such as apolipoprotein D (APOD), endothelin 1 (END1), fibroblast growth factor 7 (FGF7), gastrin (GAST), kringle containing trnasmembrane protein 1 (KREMEN1), neuropilin 1 (NRP1), serpin peptidase inhibitor clade A member 3 (SERPINA3), versican (VCAN), and others. Our findings provide a fundamental resource for better understanding of the genetic network that leads to successful embryo implantation. We demonstrate the first systems biology approach into the complex molecular network of the implantation process in humans.

Association of CCR5, TLR2, TLR4 and MBL genetic variations with genital tract infections and tubal factor infertility.

Upper genital tract infections can inflict inadequate immune response and cause Fallopian tube damage and concomitant female infertility. However, the exact role of host genetic variation in the development of tubal factor infertility remains unclear. We selected nine genetic variations in four genes involved in immune response modulation (CCR5, TLR2, TLR4 and MBL2) and assessed their association with tubal factor infertility by comparing genotype frequencies among 163 women with tubal factor infertility and 400 control individuals. The CCR5, TLR2 and TLR4 genotypes were not associated with tubal factor infertility, although the TLR4 Asp299Gly and Thr399Ile heterozygosity was associated with a decreased incidence of pathogens associated with genital tract infections in tubal factor infertility patients. In contrast, MBL2 low-producing genotypes were associated with an increased incidence of such pathogens. In addition, hyper-producing MBL2 genotype HYA/HYA and low-producing MBL2 genotypes were associated with susceptibility to tubal factor infertility, while a protective effect was associated with the high-producing MBL2 genotype HYA/LYA. Overall, these data suggest that polymorphisms in TLR4 and MBL2 play a role in receptiveness to pathogens causing genital tract infections, while MBL2 genotypes contribute to susceptibility to tubal factor infertility.

Androgen receptor epigenetic variations influence early follicular phase gonadotropin levels

Objective. We examined the influence of the androgen receptor gene (AR) CAG microsatellite (AR‐CAG) repeat polymorphism and X‐chromosome inactivation (XCI) pattern on ovarian reserve markers (follicle stimulating hormone (FSH) and antral follicle count on menstrual cycle day 3–5) and disease etiology in patients with polycystic ovarian syndrome (PCOS) or premature ovarian failure (POF). Design. Case‐control study. Population. In all, 32 women with PCOS, 26 women with POF and 79 controls were investigated. Methods. AR‐CAG and XCI were analyzed using polymerase chain reaction‐based assays following DNA digestion with the methylation‐sensitive restrictase HpaII. Main outcome measures. Distribution of AR‐CAG alleles and XCI patterns. Results. POF patients had shorter AR‐CAG microsatellites than controls. AR‐CAG microsatellite length was negatively associated with serum dehydroepiandrosterone sulfate level. The magnitude of XCI skewing was negatively and positively correlated with luteinizing hormone (LH) and FSH serum levels, respectively, during the early follicular phase, but showed no correlation with the number of early antral follicles. Conclusions. Our results suggest that AR‐CAG variations and XCI pattern exert an effect on FSH and LH values, and also have the potential to influence the etiopathogenesis of POF.

Genetic variations in vascular endothelial growth factor but not in angiotensin I-converting enzyme genes are associated with endometriosis in Estonian women

OBJECTIVE To determine plausible associations between endometriosis and vascular endothelial growth factor gene (VEGF -2578 A/C, -1154 G/A, -634 G/C and 936 C/T), also angiotensin I-converting enzyme gene (ACE -240 A/T and 2350 A/G) single nucleotide polymorphisms (SNPs), as well as their respective haplotypes. STUDY DESIGN PCR-based restriction fragment length polymorphism analysis was used to detect SNPs in VEGF and ACE genes in 150 Estonian women with endometriosis and 199 control subjects. RESULTS The CC genotype of the VEGF -2578 A/C SNP was correlated with a decreased risk of endometriosis (OR=0.40, 95% CI 0.20-0.78). Other VEGF and ACE SNPs and haplotypes were not associated with endometriosis. CONCLUSION This case-control study demonstrated that the VEGF -2578 A/C SNP may influence susceptibility to endometriosis in the Estonian population, while associations between endometriosis and other VEGF and ACE SNPs, as well as the respective haplotypes are unlikely.

VNTR I/I genotype of insulin gene is associated with the increase of follicle number independent from polycystic ovary syndrome.

Background. Polycystic ovary syndrome (PCOS) is accompanied by selective insulin resistance and enhanced ovarian steroidogenic effects of insulin. We analysed the minisatellite variations of the insulin gene (INS VNTR) with regard to the clinical features of PCOS. Methods. Retrospective, adjusted association study. Infertile patients with PCOS (n = 30) and tubal factor (n = 75) were screened for anthropometrical, clinical and ovarian morphology parameters, as well as hormonal values. INS VNTR was genotyped by its surrogate marker at −23 HphI locus. Results. INS VNTR genotype distribution was similar in PCOS and tubal infertility group. The mean ovarian follicle number was higher in VNTR I/I individuals compared to VNTR I/III and III/III individuals (adjusted OR = 1.28, p = 0.03), independent from the cause of infertility, the age, the follicle stimulating hormone level on day 3–5 of menstrual cycle, BMI and the previous surgical ovarian tissue removal. In addition, higher level of the luteinising hormone in VNTR I/I individuals was associated with the increase in follicle number. Conclusions. We suggest that INS VNTR genotypes are not associated with PCOS in general, but could have a certain influence on the phenotypic spectrum of the syndrome.

Mannose-binding lectin genotypes: potential role in tubal damage and adverse IVF outcome

The innate immune system provides the first-line defence against genital tract pathogens and is also involved in establishing and maintaining a successful pregnancy. Genetic variation of factors regulating immune response can be associated with complications after genital tract infections and may lead to unfavourable pregnancy outcomes. This study focused on four polymorphisms in the mannose binding lectin gene (MBL2) and assessed their significance in tubal damage and female fertility by comparing genotype frequencies among 388 controls and women with tubal factor infertility (n=155) or previous ectopic pregnancy (n=178). The high-producing MBL2 genotype HYA/LYA was found to have a protective effect, while the hyper-producing MBL2 genotype HYA/HYA and low-producing MBL2 genotypes were associated with susceptibility to tubal factor infertility. Also, the low-producing genotypes showed association with early pregnancy loss in IVF treatment. In conclusion, these data suggest that certain MBL2 genotypes can be associated with tubal damage in patients with evidence of Chlamydia trachomatis infection and additionally may contribute to the pathogenesis of early pregnancy loss.

Broad interests reap benefits for science

We asked young scientists this question: How do broad interests benefit your science? Scientists with a variety of hobbies responded that their extracurricular activities have enhanced a wide range of skills, from creativity to communication to resilience. Many also mentioned the value of clearing

GWAS meta-analysis highlights the hypothalamic-pituitary-gonadal axis (HPG axis) in the genetic regulation of menstrual cycle length

The normal menstrual cycle requires a delicate interplay between the hypothalamus, pituitary, and ovary. Therefore, its length is an important indicator of female reproductive health. Menstrual cycle length has been shown to be partially controlled by genetic factors, especially in the follicle stimulating hormone beta-subunit (FSHB) locus. GWAS meta-analysis of menstrual cycle length in 44,871 women of European ancestry confirmed the previously observed association with the FSHB locus and identified four additional novel signals in, or near, the GNRH1, PGR, NR5A2 and INS-IGF2 genes. These findings confirm the role of the hypothalamic-pituitary-gonadal axis in the genetic regulation of menstrual cycle length, but also highlight potential novel local regulatory mechanisms, such as those mediated by IGF2.

Demographic and evolutionary trends in ovarian function and aging

BACKGROUND The human female reproductive lifespan is regulated by the dynamics of ovarian function, which in turn is influenced by several factors: from the basic molecular biological mechanisms governing folliculogenesis, to environmental and lifestyle factors affecting the ovarian reserve between conception and menopause. From a broader point of view, global and regional demographic trends play an additional important role in shaping the female reproductive lifespan, and finally, influences on an evolutionary scale have led to the reproductive senescence that precedes somatic senescence in humans. OBJECTIVE AND RATIONALE The narrative review covers reproductive medicine, by integrating the molecular mechanisms of ovarian function and aging with short-term demographic and long-term evolutionary trends. SEARCH METHODS PubMed and Google Scholar searches were performed with relevant keywords (menopause, folliculogenesis, reproductive aging, reproductive lifespan and life history theory). The reviewed articles and their references were restricted to those written in English. OUTCOMES We discuss and summarize the rapidly accumulating information from large-scale population-based and single-reproductive-cell genomic studies, their constraints and advantages in the context of female reproductive aging as well as their possible evolutionary significance on the life history trajectory from foetal-stage folliculogenesis until cessation of ovarian function in menopause. The relevant environmental and lifestyle factors and demographic trends are also discussed in the framework of predominant evolutionary hypotheses explaining the origin and maintenance of menopause. WIDER IMPLICATIONS The high speed at which new data are generated has so far raised more questions than it has provided solid answers and has been paralleled by a lack of satisfactory interpretations of the findings in the context of human life history theory. Therefore, the recent flood of data could offer an unprecedented tool for future research to possibly confirm or rewrite human evolutionary reproductive history, at the same time providing novel grounds for patient counselling and family planning strategies.

Large scale meta-analysis highlights the hypothalamic-pituitary-gonadal (HPG) axis in the genetic regulation of menstrual cycle length.

&NA; The normal menstrual cycle requires a delicate interplay between the hypothalamus, pituitary and ovary. Therefore, its length is an important indicator of female reproductive health. Menstrual cycle length has been shown to be partially controlled by genetic factors, especially in the follicle‐stimulating hormone beta‐subunit (FSHB) locus. A genome‐wide association study meta‐analysis of menstrual cycle length in 44 871 women of European ancestry confirmed the previously observed association with the FSHB locus and identified four additional novel signals in, or near, the GNRH1, PGR, NR5A2 and INS‐IGF2 genes. These findings not only confirm the role of the hypothalamic‐pituitary‐gonadal axis in the genetic regulation of menstrual cycle length but also highlight potential novel local regulatory mechanisms, such as those mediated by IGF2.