Oocyte Maturation Arrest Research Articles

Novel mutations in PATL2 cause female infertility with oocyte germinal vesicle arrest.

Do PATL2 mutations account for female infertility with oocyte germinal vesicle (GV) arrest? Four of nine independent families with oocyte GV arrest were identified with biallelic PATL2 mutations, suggesting that these mutations may be responsible for oocyte maturation arrest in primary infertile women. Recently, two independent studies have demonstrated that infertility in some women with oocyte maturation arrest at the GV stage was caused by biallelic mutations in PATL2. PATL2 encodes protein PAT1 homolog 2, an RNA-binding protein that may act as a translational repressor. In this study, nine unrelated primary infertile females presenting with oocyte GV arrest were recruited during the treatment of early rescue ICSI or ICSI from January 2013 to December 2016. Genomic DNA was isolated from blood samples obtained from all nine affected individuals and all of their available family members. All the coding regions of PATL2 were sequenced by Sanger sequencing. The pathogenicity of the identified variants and their possible effects on the protein were evaluated in silico. Five novel point mutations and one recurrent splicing mutation in PATL2 were identified in four of nine (44.4%) unrelated patients. We found a consanguineous family with a homozygous missense mutation in two affected sisters, and their fertile brother. There were no clear phenotypic differences in oocytes between the patient with the homozygous missense mutation, patients with nonsense mutations and undiagnosed patients. n/a. The function of PATL2 remains largely unknown. Both the exact pathogenic mechanism(s) of mutated PATL2 causing human oocyte maturation arrest and the strategies to overcome this condition should be further investigated in the future. According to our data, mutations in PATL2 account for 44.4% of the individuals with oocyte GV arrest. Our study further confirms that PATL2 is required for human oocyte maturation and female fertility, which indicates a potential prognostic value of testing for PATL2 mutations in primary infertile women with oocyte maturation arrest. Natural Science Foundation of Anhui Province (1808085MH241), National Natural Science Foundation of China (81401251 and 81370757) and Central Guided Local Development of Science and Technology Special Fund (2016080802D114) supported this study. None of the authors have any competing interests.

Mutation analysis of the TUBB8 gene in primary infertile women with arrest in oocyte maturation

Tubulin beta eight class VIII (TUBB8) is a subtype of β-tubulin that only exists in primates. Mutations in the TUBB8 gene have been proven to cause oocyte maturation arrest. The aim of this study was to identify the new types of mutations in TUBB8. Six women (families) with oocyte maturation arrest and 100 healthy controls were recruited. The sequence of the TUBB8 gene was amplified and analyzed by Sanger sequencing, which revealed a de novo heterozygous variant c.292G > A (p.G98R) of TUBB8 in one affected individual. This TUBB8 variant was absent in the 100 fertile females and was predicted to be highly damaging to the function of the TUBB8 protein by SIFT and PolyPhen-2. This novel variant extends the spectrum of TUBB8 mutations and the presence of a TUBB8 mutation is being considered to be indicative of a poor prognosis for the success of assisted reproductive treatment.

Biallelic Mutations in PATL2 Cause Female Infertility Characterized by Oocyte Maturation Arrest

Oocyte maturation arrest results in female infertility, but the genetic determinants of human oocyte maturation arrest remain largely unknown. Previously, we identified TUBB8 mutations responsible for human oocyte maturation arrest, indicating the important role of genetic factors in the disorder. However, TUBB8 mutations account for only around 30% of individuals with oocyte maturation arrest; thus, the disorder is likely to involve other genetic factors that are as yet unknown. Here, we initially identified a homozygous nonsense mutation of PATL2 (c.784C>T [p.Arg262∗]) in a consanguineous family with a phenotype characterized by human oocyte germinal vesicle (GV) arrest. Subsequent mutation screening of PATL2 in a cohort of 179 individuals identified four additional independent individuals with compound-heterozygous PATL2 mutations with slight phenotypic variability. A genetic burden test further confirmed the genetic contribution of PATL2 to human oocyte maturation arrest. By western blot in HeLa cells, identification of splicing events in affected individuals' granulosa cells, and immunostaining in affected individuals' oocytes, we provide evidence that mutations in PATL2 lead to decreased amounts of protein. These findings suggest an important role for PATL2 mutations in oocyte maturation arrest and expand our understanding of the genetic basis of female infertility.

Female Infertility Caused by Mutations in the Oocyte-Specific Translational Repressor PATL2

Infertility is a relatively common disorder of the reproductive system and remains unexplained in many cases. Invitro fertilization techniques have uncovered previously unrecognized infertility phenotypes, including oocyte maturation arrest, the molecular etiology of which remains largely unknown. We report two families affected by female-limited infertility caused by oocyte maturation failure. Positional mapping and whole-exome sequencing revealed two homozygous, likely deleterious variants in PATL2, each of which fully segregates with the phenotype within the respective family. PATL2 encodes a highly conserved oocyte-specific mRNP repressor of translation. Previous data have shown the strict requirement for PATL2 in oocyte-maturation in model organisms. Data gathered from the families in this study suggest that the role of PATL2 is conserved in humans and expand our knowledge of the factors that are necessary for female meiosis.

Mutation analysis of the TUBB8 gene in nine infertile women with oocyte maturation arrest

Mutations in the tubulin beta 8 class VIII (TUBB8) gene have been proven to cause oocyte maturation arrest. The aim of this study was to describe newly discovered mutations in TUBB8 and to investigate the prevalence of TUBB8 mutations in our cohort. Nine women with oocyte maturation arrest and 100 fertile female controls were recruited. Sanger sequencing of the coding regions of TUBB8 revealed a heterozygous variant c.535G > A (p.V179M) in two unrelated affected individuals and a heterozygous variant c.5G > T (p.R2M) in one affected individual. These TUBB8 variants were inherited from the unaffected fathers and were absent in 100 fertile female control individuals. In total, 33.33% (3/9) of the affected individuals in our cohort obtained a clear genetic diagnosis through sequencing of the TUBB8 gene. These two novel variants extend the spectrum of TUBB8 mutations and this study confirmed that TUBB8 mutations occur in a high proportion of infertile women with oocyte maturation arrest.

Novel zona pellucida gene variants identified in patients with oocyte anomalies

To detect ZP (zona pellucida) gene (ZP1-ZP4) mutations in patients with oocyte anomalies. Case-control genetic study. University-based reproductive medicine center. A total of 92 infertile patients with repeated cycles of oocyte maturation arrest (group I, n = 49) or oocyte morphologic defect (group II, n = 43) as well as 373 healthy controls. Genomic DNA extracted from peripheral blood and coding regions of ZP genes amplified by polymerase chain reaction and sequenced by a DNA analyzer. Variant prediction of ZP genes with software. In group I with oocyte maturation arrest, no novel variants were found. In group II with oocyte morphologic defects, four novel variants, two in the ZP1 gene [c.247T>C (p.W83R) and c.1413G>A (p.W471X)] and two in the ZP2 gene [c.1599G>T (p.R533S) and c.1696T>C (p.C566R)] were detected in 4 of 43 patients (approximately 9%) but were absent from the controls. Protein alignments showed that the four variants were highly conserved among different species, and all four variants were predicted to be deleterious by gene software predictions. ZP gene variants may account for patients with oocyte morphologic abnormalities but not for those with oocyte maturation arrest.

An isoform of Taiman that contains a PRD-repeat motif is indispensable for transducing the vitellogenic juvenile hormone signal in Locusta migratoria

Taiman (Tai) has been recently identified as the dimerizing partner of juvenile hormone (JH) receptor, Methoprene-tolerant (Met). However, the role of Tai isoforms in transducing vitellogenic signal of JH has not been determined. In this study, we show that the migratory locust Locusta migratoria has two Tai isoforms, which differ in an INDEL-1 domain with the PRD-repeat motif rich in histidine and proline at the C-terminus. Tai-A with the INDEL-1 is expressed at levels about 50-fold higher than Tai-B without the INDEL-1 in the fat body of vitellogenic adult females. Knockdown of Tai-A but not Tai-B results in a substantial reduction of vitellogenin expression in the fat body accompanied by the arrest of ovarian development and oocyte maturation, similar to that caused by depletion of both Tai isoforms. Either Tai-A or Tai-B combined with Met can induce target gene transcription in response to JH, but Tai-A appears to mediate a significantly higher transactivation. Our data suggest that the INDEL-1 domain plays a critical role in Tai function during reproduction as Tai-A appears be more active than Tai-B in transducing the vitellogenic JH signal in L. migratoria.

Novel mutations and structural deletions in TUBB8: expanding mutational and phenotypic spectrum of patients with arrest in oocyte maturation, fertilization or early embryonic development.

Are there any new type of mutations and novel phenotypes in patients with arrest in oocyte maturation, fertilization or early embryonic development having tubulin beta eight class VIII (TUBB8) mutations? We identified new types of mutations in TUBB8 associated with maturation, fertilization and developmental arrest. We previously found heterozygous mutations and a homozygous frameshift/internal seven amino acid deletion in TUBB8 that are responsible for oocyte maturation arrest. We recruited 10 new primary infertility patients from 9 families from December 2015 to May 2016, most of which exhibited failures in oocyte maturation. Ten primary infertility patients were recruited from the reproduction centers in local hospitals. Genomic DNA samples from the affected individuals, their family members and healthy controls were extracted from peripheral blood. TUBB8 in the DNA samples were sequenced by Sanger sequencing. TUBB8 sequence was then aligned by CodonCode software to identify rare variants. ExAC database was used to search frequency of corresponding mutations. In silico analysis of mutations was used by Polyphen and PROVEAN. Phenotypes of oocytes and embryos were evaluated by light microscopy, polarization microscopy or immunolabeling. Besides several novel heterozygous missense mutations, we also identified other new types of genetic variants, including homozygous mutations and a de novo compound heterozygous mutation. We also found a patient with a homozygous deletion of the whole TUBB8 gene, which is the first reported case of a large structural variation in this gene. In addition, we found different mutations in TUBB8 that could result in variability in oocyte/embryo phenotypes, including oocyte maturation arrest, first polar body (PB1) oocytes that cannot be fertilized, and PB1 oocytes that can be fertilized but arrest at an early embryonic stage. The exact molecular mechanism has not been analyzed and should be further investigated in the future. In addition, immunostaining of more oocytes with mutations and checking spindle status of oocytes with mutations non-invasively by polarization microscopy needs to be done in order to determine exact stage of PB1 oocytes and the functional differences of these mutations. The results not only emphasize the important role of TUBB8 in oocyte maturation, fertilization and early embryonic development but they also provide a basis for determining the genetic variations in TUBB8 as a potential additional criterion for evaluating the quality of patients' functional PB1 oocytes. National Key R&D Program of China (2016YFC1000600); Basic Research Program of China (2015CB943300); National Natural Science Foundation of China (81270747 and 81571501). No competing interests declared.

Mutations in TUBB8 cause a multiplicity of phenotypes in human oocytes and early embryos

BackgroundTUBB8 is a primate-specific β-tubulin isotype whose expression is confined to oocytes and the early embryo. We previously found that mutations in TUBB8 caused oocyte maturation arrest. The objective was...

C-Fos Repression by Piwi Regulates Drosophila Ovarian Germline Formation and Tissue Morphogenesis.

Drosophila melanogaster Piwi functions within the germline stem cells (GSCs) and the somatic niche to regulate GSC self-renewal and differentiation. How Piwi influences GSCs is largely unknown. We uncovered a genetic interaction between Piwi and c-Fos in the somatic niche that influences GSCs. c-Fos is a proto-oncogene that influences many cell and developmental processes. In wild-type ovarian cells, c-Fos is post-transcriptionally repressed by Piwi, which destabilized the c-Fos mRNA by promoting the processing of its 3′ untranslated region (UTR) into Piwi-interacting RNAs (piRNAs). The c-Fos 3′ UTR was sufficient to trigger Piwi-dependent destabilization of a GFP reporter. Piwi represses c-Fos in the somatic niche to regulate GSC maintenance and differentiation and in the somatic follicle cells to affect somatic cell disorganization, tissue dysmorphogenesis, oocyte maturation arrest, and infertility.

Oocyte maturation arrest in endometriosis is caused by elevated levels of Reactive Oxygen Species and enforced via a DNA Damage Response and the Spindle Assembly Checkpoint pathway

Oocyte maturation arrest in endometriosis is caused by elevated levels of Reactive Oxygen Species and enforced via a DNA Damage Response and the Spindle Assembly Checkpoint pathway

Mutations in TUBB8 and Human Oocyte Meiotic Arrest

BackgroundHuman reproduction depends on the fusion of a mature oocyte with a sperm cell to form a fertilized egg. The genetic events that lead to the arrest of human oocyte maturation are unknown.MethodsWe sequenced the exomes of five members of a four-generation family, three of whom had infertility due to oocyte meiosis I arrest. We performed Sanger sequencing of a candidate gene, TUBB8, in DNA samples from these members, additional family members, and members of 23 other affected families. The expression of TUBB8 and all other β-tubulin isotypes was assessed in human oocytes, early embryos, sperm cells, and several somatic tissues by means of a quantitative reverse-transcriptase–polymerase-chain-reaction assay. We evaluated the effect of the TUBB8 mutations on the assembly of the heterodimer consisting of one α-tubulin polypeptide and one β-tubulin polypeptide (α/β-tubulin heterodimer) in vitro, on microtubule architecture in HeLa cells, on microtubule dynamics in yeast cells, and on spindle assembly in mouse and human oocytes.ResultsWe identified seven mutations in the primate-specific gene TUBB8 that were responsible for oocyte meiosis I arrest in 7 of the 24 families. TUBB8 expression is unique to oocytes and the early embryo, in which this gene accounts for almost all the expressed β-tubulin. The mutations affect chaperone-dependent folding and assembly of the α/β-tubulin heterodimer, disrupt microtubule behavior on expression in cultured cells, alter microtubule dynamics in vivo, and cause catastrophic spindle-assembly defects and maturation arrest on expression in mouse and human oocytes.ConclusionsTUBB8 mutations have dominant-negative effects that disrupt microtubule behavior and oocyte meiotic spindle assembly and maturation, causing female infertility. (Funded by the National Basic Research Program of China and others.)

Maturation Arrest of Oocytes?Case Reports

We report three case of maturation arrest of oocyte two of which were treated with oocyte donation. A total failure of human oocytes to complete meiosis is rarely observed during assisted conception cycles. Maturation arrest of oocytes may occur at various stages of the cell cycle from germinal vesicle (GV) stage to metaphase one and two (MI and MII). Two cases that presented to us had unexplained infertility, but the third case had rheumatoid arthritis, which may result in an immune problem. In all the three couples, maturation arrest of the oocytes was noted repeatedly in all cycles of assisted reproductive technology (ART). In the first case the oocytes were arrested at both, the GV and metaphase I stage, in the second and third case arrest was noted in MI. Failure to resume meiosis in vivo may arise at one of the following three levels: iƒ¼ absent or incomplete luteinizing hormone(LH) effect iƒ¼ derangements in the signaling mechanism from the surrounding cumulus cells iƒ¼ intrinsic oocyte factors Currently no therapeutic approach would help to overcome the blocks in oocyte maturation and sustain successful in-vitro fertilization (IVF) Oocyte maturation arrest may be the cause of infertility in some couples previously classified as having unexplained infertility. The recognition of oocyte maturation arrest as a specific factor for infertility tells, how important the oocyte factor is. All the three patients were advised oocyte donation as the literature quotes very poor pregnancy rate with own oocyte. One patient conceived in the second cycle, whereas the other patient failed to conceive, despite transfer of good quality embryos.

Improvement in in vitro fertilization outcome following in vivo synchronization of oocyte maturation in mice.

Synchronization of oocyte maturation in vitro has been shown to produce higher in vitro fertilization (IVF) rates than those observed in oocytes matured in vitro without synchronization. However, the increased IVF rates never exceeded those observed in oocytes matured in vivo without synchronization. This study was therefore designed to define the effect of in vivo synchronization of oocyte maturation on IVF rates. Mice were superovulated and orally treated with 7.5 mg cilostazol (CLZ), a phosphodiesterase 3A (PDE3A) inhibitor, to induce ovulation of immature oocytes at different stages depending on frequency and time of administration of CLZ. Mice treated with CLZ ovulated germinal vesicle (GV) or metaphase I (MI) oocytes that underwent maturation in vitro or in vivo (i.e. in the oviduct) followed by IVF. Superovulated control mice ovulated mature oocytes that underwent IVF directly upon collection. Ovulated MI oocytes matured in vitro or in vivo had similar maturation rates but significantly higher IVF rates, 2-4 cell embryos, than those observed in control oocytes. Ovulated GV oocytes matured in vitro showed similar maturation rates but significantly higher IVF rates than those observed in control oocytes. However, ovulated GV oocytes matured in vivo had significantly lower IVF rates than those noted in control oocytes. It is concluded that CLZ is able to synchronize oocyte maturation and improve IVF rates in superovulated mice. CLZ may be capable of showing similar effects in humans, especially since temporal arrest of human oocyte maturation with other PDE3A inhibitors in vitro was found to improve oocyte competence level. The capability of a clinically approved PDE3A inhibitor to improve oocyte fertilization rates in mice at doses extrapolated from human therapeutic doses suggests the potential scenario of the inclusion of CLZ in superovulation programs. This may improve IVF outcomes in infertile patients.

GnRH agonist protocol versus GnRH antagonist protocol in assisted reproduction

GnRH agonist protocol versus GnRH antagonist protocol in assisted reproduction

In vitro oocyte maturation from unstimulated cycles: does it offer a realistic chance to overcome the problem of repeated oocyte maturation arrest in IVF?

This report describes the use of in vitro oocyte maturation in two patients with history of repeated oocyte maturation arrest (OMA) from in vitro fertilization. Based on these two cases, in vitro oocyte maturation from unstimulated cycles seems not an alternative treatment option for the patients with history of OMA.

Oocyte maturation failure: a syndrome of bad eggs

To show that disruption of meiotic competence results in cell cycle arrest, and the production of immature oocytes that are not capable of fertilization. Through an extensive review of animal studies and clinical case reports, we define the syndrome of oocyte maturation failure as a distinct oocyte disorder, present a classification system based on clinical parameters, and discuss the potential molecular origins for the disease.

Maturation arrest of human oocytes at germinal vesicle stage

Maturation arrest of human oocytes may occur at various stages of the cell cycle. A total failure of human oocytes to complete meiosis is rarely observed during assisted conception cycles. We describe here a case of infertile couples for whom all oocytes repeatedly failed to mature at germinal vesicle (GV) stage during in vitro fertilization/Intra cytoplasmic sperm injection (IVF/ICSI). The patient underwent controlled ovarian stimulation followed by oocyte retrieval and IVF/ICSI. The oocytes were stripped off cumulus cells prior to the ICSI procedure and their maturity status was defined. The oocyte maturation was repeatedly arrested at the GV. Oocyte maturation arrest may be the cause of infertility in this couple. The recognition of oocyte maturation arrest as a specific medical condition may contribute to the characterization of the currently known as “oocyte factor.” The cellular and genetic mechanisms causing oocyte maturation arrest should be the subject for further investigation.

Maturation arrest of oocytes at prophase I stage as infertility cause: A case report

Repeated in vitro fertilization failure due to maturation arrest of whole retrieved oocyte has been a difficult challenge and no other therapeutic approaches are currently available. A 35-year-old woman presented with repeated oocyte maturation arrest at the meiosis I stage. The patient underwent controlled ovarian stimulation and ten germinal vesicle break-downed (GVBD) oocytes were collected. Our interventions either mechanically (sham intracytoplasmic sperm injection) or chemically activated (calcium-ionophore) could not overcome the maturation arrest. All oocytes failed to mature showed negative staining for anti-tubulin antibody with well-condensed chromosomes. Our case was characterized by the occurrence of GVBD and chromosome condensation but it showed arrested nuclear maturation at the prophase I stage resulting non-extrusion of the first polar body. Maturation arrest at the prophase I stage could be one of the infertility causes. The underlying mechanisms and strategies to overcome oocyte maturation arrest should be further investigated.

In vitro maturation for patients with repeated in vitro fertilization failure due to “oocyte maturation abnormalities”

To investigate the efficacy of in vitro oocyte maturation (IVM) in women with repeated failure of IVF treatments due to follicular developmental abnormalities. Prospective longitudinal study. The IVF unit of a university-affiliated medical center. Seven women with three or more IVF failures due to abnormal oocyte development resulting in no egg retrieval (empty follicle syndrome [EFS]), oocyte maturation arrest, or failure of fertilization. Immature oocyte collection, with or without minimal ovarian stimulation, IVM of the oocytes, insemination by intracytoplasmic sperm injection (ICSI), and embryo transfer. Number of aspirated oocytes, maturation, fertilization and cleavage rates, pregnancy, and ongoing pregnancy. Seven women underwent seven IVM cycles. Four of them received a minimal stimulation of 75 IU FSH for 3-4 days. Oocytes were retrieved from all subjects (mean 7.1 +/- 3.3 oocytes/cycle). The in vitro maturation rate was 39.6% (mean 2.7 +/- 2.9 matured oocytes available for fertilization in four patients). The mean fertilization rate was 45.8% +/- 31.6%. Four women had embryo transfer. Two patients with previous genuine EFS conceived and delivered. IVM should be considered for women with previous genuine EFS. The role of IVM in other indications of oocyte maturation deficits warrants further investigation.