No evidence for mutations in NLRP7, NLRP2 or KHDC3L in women with unexplained recurrent pregnancy loss or infertility

Pyroptosis and Inflammasome-Related Genes-NLRP3, NLRC4 and NLRP7 Polymorphisms Were Associated with Risk of Lung Cancer

Background

Cancer development and tumor immune microenvironment remodeling are closely linked to pyroptosis and inflammasome activation. However, little information is available in single nucleotide polymorphisms (SNPs) in pyroptosis and inflammasome-related genes in patients with lung cancer. This study aims to evaluate the associations between pyroptosis-related gene (NLRP3, NLRC4, and NLRP7) polymorphisms and the risk of lung cancer.

Methods

The MassARRAY platform was used to genotype six SNPs of the NLRP3, NLRC4, and NLRP7 genes in 660 lung cancer cases and 660 controls.

Results

Individuals with rs35829419-A, rs385076-C, and rs775882-T alleles exhibited a higher risk of lung cancer (p < 0.01), while rs212704-T appears protective (p = 0.006). The rs35829419-AA, rs385076-TC/CC, and rs775882-CT/TT genotypes were associated with various degrees of elevated risk of lung cancer (p<0.02), whereas rs212704-TT was associated with a reduced risk of the disease (p=0.014). Genetic models analysis showed that rs35829419, rs385076, and rs775882 was associated with an increased risk of lung cancer, while rs212704 was related to a reduced risk in all three models (p < 0.05). The four SNPs remained significant in smoker and nonsmoker subgroups (p < 0.05). However, rs35829419 was correlated with risk of adenocarcinoma and small cell lung cancer, and rs212704 was only protective for squamous cell carcinoma. The rs385076 and rs775882 were associated with all three pathological types (p < 0.01).

Conclusion

Besides providing candidate markers for identification of high-risk populations and early prevention of the disease, our research also provided new insight into anti-tumor strategies targeting inflammasomes and pyroptosis.

Novel genetic variants of KHDC3L and other members of the subcortical maternal complex associated with Beckwith-Wiedemann syndrome or Pseudohypoparathyroidism 1B and multi-locus imprinting disturbances

BACKGROUND

Beckwith-Wiedemann syndrome (BWS) and Pseudohypoparathyroidism type 1B (PHP1B) are imprinting disorders (ID) caused by deregulation of the imprinted gene clusters located at 11p15.5 and 20q13.32, respectively. In both of these diseases a subset of the patients is affected by multi-locus imprinting disturbances (MLID). In several families, MLID is associated with damaging variants of maternal-effect genes encoding protein components of the subcortical maternal complex (SCMC). However, frequency, penetrance and recurrence risks of these variants are still undefined. In this study, we screened two cohorts of BWS patients and one cohort of PHP1B patients for the presence of MLID, and analysed the positive cases for the presence of maternal variants in the SCMC genes by whole exome-sequencing and in silico functional studies.

RESULTS

We identified 10 new cases of MLID associated with the clinical features of either BWS or PHP1B, in which segregate 13 maternal putatively damaging missense variants of the SCMC genes. The affected genes also included KHDC3L that has not been associated with MLID to date. Moreover, we highlight the possible relevance of relatively common variants in the aetiology of MLID.

CONCLUSION

Our data further add to the list of the SCMC components and maternal variants that are involved in MLID, as well as of the associated clinical phenotypes. Also, we propose that in addition to rare variants, common variants may play a role in the aetiology of MLID and imprinting disorders by exerting an additive effect in combination with rarer putatively damaging variants. These findings provide useful information for the molecular diagnosis and recurrence risk evaluation of MLID-associated IDs in genetic counselling.

KH domain containing 3 like (KHDC3L) frame-shift mutation causes both recurrent pregnancy loss and hydatidiform mole

OBJECTIVE

Recurrent pregnancy loss (RPL) is a common infertility-related complication that affects approximately 1-3 % of women worldwide. Known causes of etiology are found in approximately half the cases but the other half remain unexplained. It is estimated that several thousands of genes contribute to reproductive success in mammals and the genetic causes of RPL cannot be fully addressed through targeted genetic tests. In recent years, massive parallel sequencing technologies has helped discovering many causal mutations in hereditary diseases such as RPL.

STUDY DESIGN

Using whole-exome sequencing (WES), we studied a large multiplex consanguineous family with multiple cases of RPL and hydatidiform moles (HM). In addition, targeted Sanger sequencing was applied to 40 additional non-related individuals with RPL.

RESULTS

The use of WES permitted to identify the pathogenic variant in KHDC3L (c.322_325delGACT) in related who experienced RPL with or without HM. Sanger sequencing confirmed the segregation of the mutation throughout the pedigree and permitted to establish this variant as the genetic cause responsible for RPL and HM in this family.

CONCLUSION

KHDC3L is well established as a susceptibility gene for HM but we confirmed here that KHDC3L deleterious variants can also induce RPL. In addition, we observed a genotype-phenotype correlation, demonstrating that women with a truncating KHDC3L homozygous variant could not sustain a pregnancy and often had pregnancy losses mainly due to HM while those with the same heterozygous variant could have children but often endured RPL with no HM.

NLRP3 Inflammasome and Its Critical Role in Gynecological Disorders and Obstetrical Complications

Inflammasomes, intracellular, multimeric protein complexes, are assembled when damage signals stimulate nucleotide-binding oligomerization domain receptors (NLRs). Several inflammasomes have been reported, including the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3), NLRP1, NLRP7, ice protease-activating factor (IPAF), absent in melanoma 2 (AIM2) and NLR family CARD domain-containing protein 4 (NLRC4). Among these inflammasomes, the NLRP3 inflammasome is the most well-studied in terms of structure and function. Unlike other inflammasomes that can only be activated by a finite number of pathogenic microorganisms, the NLRP3 inflammasome can be activated by the imbalance of the internal environment and a large number of metabolites. The biochemical function of NLRP3 inflammasome is to activate cysteine-requiring aspartate proteinase-1 (caspase-1), which converts pro-IL-1β and pro-IL-18 into their active forms, namely, IL-1β and IL-18, which are then released into the extracellular space. The well-established, classic role of NLRP3 inflammasome has been implicated in many disorders. In this review, we discuss the current understanding of NLRP3 inflammasome and its critical role in gynecological disorders and obstetrical complications.

Reproductive Outcomes from Maternal Loss of Nlrp2 Are Not Improved by IVF or Embryo Transfer Consistent with Oocyte-Specific Defect

Nlrp2 encodes a protein of the oocyte subcortical maternal complex (SCMC), required for embryo development. We previously showed that loss of maternal Nlrp2 in mice causes subfertility, smaller litters with birth defects, and growth abnormalities in offspring, indicating that Nlrp2 is a maternal effect gene and that all embryos from Nlrp2-deficient females that were cultured in vitro arrested before the blastocysts stage. Here, we used time-lapse microscopy to examine the development of cultured embryos from superovulated Nlrp2-deficient and wild-type mice after in vivo and in vitro fertilization. Embryos from Nlrp2-deficient females had similar abnormal cleavage and fragmentation and arrested by blastocyst stage, irrespective of fertilization mode. This indicates that in vitro fertilization does not further perturb or improve the development of cultured embryos. We also transferred embryos from superovulated Nlrp2-deficient and wild-type females to wild-type recipients to investigate if the abnormal reproductive outcomes of Nlrp2-deficient females are primarily driven by oocyte dysfunction or if a suboptimal intra-uterine milieu is a necessary factor. Pregnancies with transferred embryos from Nlrp2-deficient females produced smaller litters, stillbirths, and offspring with birth defects and growth abnormalities. This indicates that the reproductive phenotype is oocyte-specific and is not rescued by development in a wild-type uterus. We further found abnormal DNA methylation at two maternally imprinted loci in the kidney of surviving young adult offspring, confirming persistent DNA methylation disturbances in surviving offspring. These findings have implications for fertility treatments for women with mutations in NLRP2 and other genes encoding SCMC proteins.

KHDC3L mutation causes recurrent pregnancy loss by inducing genomic instability of human early embryonic cells

Recurrent pregnancy loss (RPL) is an important complication in reproductive health. About 50% of RPL cases are unexplained, and understanding the genetic basis is essential for its diagnosis and prognosis. Herein, we report causal KH domain containing 3 like (KHDC3L) mutations in RPL. KHDC3L is expressed in human epiblast cells and ensures their genome stability and viability. Mechanistically, KHDC3L binds to poly(ADP-ribose) polymerase 1 (PARP1) to stimulate its activity. In response to DNA damage, KHDC3L also localizes to DNA damage sites and facilitates homologous recombination (HR)-mediated DNA repair. KHDC3L dysfunction causes PARP1 inhibition and HR repair deficiency, which is synthetically lethal. Notably, we identified two critical residues, Thr145 and Thr156, whose phosphorylation by Ataxia-telangiectasia mutated (ATM) is essential for KHDC3L’s functions. Importantly, two deletions of KHDC3L (p.E150_V160del and p.E150_V172del) were detected in female RPL patients, both of which harbor a common loss of Thr156 and are impaired in PARP1 activation and HR repair. In summary, our study reveals both KHDC3L as a new RPL risk gene and its critical function in DNA damage repair pathways.

Recurrent pregnancy loss is an important complication in reproductive health, and about 50% of cases remain unexplained. This study shows that KHDC3L safeguards the genomic stability of human early embryonic cells, and damaging mutations in its gene cause recurrent pregnancy loss in humans.

The significance of the placental genome and methylome in fetal and maternal health

The placenta is a crucial organ for supporting a healthy pregnancy, and defective development or function of the placenta is implicated in a number of complications of pregnancy that affect both maternal and fetal health, including maternal preeclampsia, fetal growth restriction, and spontaneous preterm birth. In this review, we highlight the role of the placental genome in mediating fetal and maternal health by discussing the impact of a variety of genetic alterations, from large whole-chromosome aneuploidies to single-nucleotide variants, on placental development and function. We also discuss the placental methylome in relation to its potential applications for refining diagnosis, predicting pathology, and identifying genetic variants with potential functional significance. We conclude that understanding the influence of the placental genome on common placental-mediated pathologies is critical to improving perinatal health outcomes.

Potential genetic causes of miscarriage in euploid pregnancies: a systematic review

BACKGROUND

Approximately 50% of pregnancy losses are caused by chromosomal abnormalities, such as aneuploidy. The remainder has an apparent euploid karyotype, but it is plausible that there are cases of pregnancy loss with other genetic aberrations that are not currently routinely detected. Studies investigating the use of exome sequencing and chromosomal microarrays in structurally abnormal pregnancies and developmental disorders have demonstrated their clinical application and/or potential utility in these groups of patients. Similarly, there have been several studies that have sought to identify genes that are potentially causative of, or associated with, spontaneous pregnancy loss, but the evidence has not yet been synthesized.

OBJECTIVE AND RATIONALE

The objective was to identify studies that have recorded monogenic genetic contributions to pregnancy loss in euploid pregnancies, establish evidence for genetic causes of pregnancy loss, identify the limitations of current evidence, and make recommendations for future studies. This evidence is important in considering additional research into Mendelian causes of pregnancy loss and appropriate genetic investigations for couples experiencing recurrent pregnancy loss.

SEARCH METHODS

A systematic review was conducted in MEDLINE (1946 to May 2018) and Embase (1974 to May 2018). The search terms ‘spontaneous abortion’, ‘miscarriage’, ‘pregnancy loss’, or ‘lethal’ were used to identify pregnancy loss terms. These were combined with search terms to identify the genetic contribution including ‘exome’, ‘human genome’, ‘sequencing analysis’, ‘sequencing’, ‘copy number variation’, ‘single-nucleotide polymorphism’, ‘microarray analysis’, and ‘comparative genomic hybridization’. Studies were limited to pregnancy loss up to 20 weeks in humans and excluded if the genetic content included genes that are not lethal in utero, PGD studies, infertility studies, expression studies, aneuploidy with no recurrence risk, methodologies where there is no clinical relevance, and complex genetic studies. The quality of the studies was assessed using a modified version of the Newcastle–Ottawa scale.

OUTCOMES

A total of 50 studies were identified and categorized into three themes: whole-exome sequencing studies; copy number variation studies; and other studies related to pregnancy loss including recurrent molar pregnancies, epigenetics, and mitochondrial DNA aberrations. Putatively causative variants were found in a range of genes, including CHRNA1 (cholinergic receptor, nicotinic, alpha polypeptide 1), DYNC2H1 (dynein, cytoplasmic 2, heavy chain 1), and RYR1 (ryanodine receptor 1), which were identified in multiple studies. Copy number variants were also identified to have a causal or associated link with recurrent miscarriage.

WIDER IMPLICATIONS

Identification of genes that are causative of or predisposing to pregnancy loss will be of significant individual patient impact with respect to counselling and treatment. In addition, knowledge of specific genes that contribute to pregnancy loss could also be of importance in designing a diagnostic sequencing panel for patients with recurrent pregnancy loss and also in understanding the biological pathways that can cause pregnancy loss.

Downregulation of NLRP2 inhibits HUVEC viability by inhibiting the MAPK signaling pathway

Nucleotide-binding oligomerization domain (NOD)-like receptor proteins (NLRPs) are a subfamily of NOD-like receptors (NLRs) that mainly participate in innate immunity. Among the 14 NLRPs, studies on NLRP2 are few and mostly focus on its functions in reproduction and embryonic development. To the best of the authors' knowledge, there has been no research on the function of NLRP2 in human umbilical vein endothelial cells (HUVECs). The present study knockdown the expression of NLRP2 by transfecting a short interfering (si)RNA (siNLRP2) into HUVECs and investigating its effects on HUVECs. It was identified using a Cell Counting kit-8 assay that knockdown of NLRP2 can inhibit cell proliferation in HUVECs. The results of wound healing and Transwell assays indicated that migration and invasion were also suppressed by siNLRP2 transfection in HUVECs. Flow cytometry demonstrated that siNLRP2 induced cell cycle arrest and apoptosis in HUVECs. Western blot analysis revealed that the expression levels of cell cycle and apoptosis-associated proteins were markedly changed. In addition, knockdown of NLRP2 inhibited the mitogen-activated protein kinase (MAPK) signaling pathway by elevating extracellular signal-regulated kinase phosphorylation levels and reducing proto-oncogene serine/threonine-protein kinase expression. Taken together, it was concluded that NLRP2 served an important role in maintaining cell viability, proliferation and motility in HUVECs, mainly by promoting the MAPK signaling pathway.

NLRPs, the subcortical maternal complex and genomic imprinting

Before activation of the embryonic genome, the oocyte provides many of the RNAs and proteins required for the epigenetic reprogramming and the transition to a totipotent state. Targeted disruption of a subset of oocyte-derived transcripts in mice results in early embryonic lethality and cleavage-stage embryonic arrest as highlighted by the members of the subcortical maternal complex (SCMC). Maternal-effect recessive mutations of NLRP7, KHDC3L and NLRP5 in humans are associated with variable reproductive outcomes, biparental hydatidiform moles (BiHM) and widespread multi-locus imprinting disturbances. The precise mechanism of action of these genes is unknown, but the maternal-effect phenomenon suggests a function during early pre-implantation development, while biochemical and genetic studies implement them as SCMC members or interacting partners. In this review article, we discuss the role of the NLRP family members and the SCMC proteins in the establishment of genomic imprints and post-zygotic methylation maintenance, the recent advances made in the understanding of the biology involved in BiHM formation and the wider roles of the SCMC in mammalian reproduction.