|
General Comment |
Live imaging RNAi screen reveals genes essential for meiosis in mammalian oocytes. Pfender S et al. (2015) During fertilization, an egg and a sperm fuse to form a new embryo. Eggs develop from oocytes in a process called meiosis. Meiosis in human oocytes is highly error-prone, and defective eggs are the leading cause of pregnancy loss and several genetic disorders such as Down's syndrome. Which genes safeguard accurate progression through meiosis is largely unclear. Here we develop high-content phenotypic screening methods for the systematic identification of mammalian meiotic genes. We targeted 774 genes by RNA interference within follicle-enclosed mouse oocytes to block protein expression from an early stage of oocyte development onwards. We then analysed the function of several genes simultaneously by high-resolution imaging of chromosomes and microtubules in live oocytes and scored each oocyte quantitatively for 50 phenotypes, generating a comprehensive resource of meiotic gene function. The screen generated an unprecedented annotated data set of meiotic progression in 2,241 mammalian oocytes, which allowed us to analyse systematically which defects are linked to abnormal chromosome segregation during meiosis, identifying progression into anaphase with misaligned chromosomes as well as defects in spindle organization as risk factors. This study demonstrates how high-content screens can be performed in oocytes, and allows systematic studies of meiosis in mammals.//////////////////
NCBI Summary:
The protein encoded by this gene is a nucleocytoplasmic shuttle protein for the translation initiation factor eIF4E. This shuttle protein interacts with the importin alpha-beta complex to mediate nuclear import of eIF4E. It is predominantly cytoplasmic; its own nuclear import is regulated by a nuclear localization signal and nuclear export signals. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Aug 2009]
|
|
Comment |
Clast4, the murine homologue of human eIF4E-Transporter, is highly expressed in developing oocytes and post-translationally modified at meiotic maturation Villaescusa JC, et al .
In metazoans, translational regulation of a set of maternal mRNAs directs oocyte maturation and early embryogenesis. These transcripts are often kept dormant until their products are spatially and temporally required in development. The interaction between general translation factors (i.e. eIF4E) and their specific interactors influences translation initiation. A search of the protein database for a mouse homologue of the Drosophila Cup protein, a translational repressor during female germ-line development, identified the product of the Clast4 gene. In this report, we show that Clast4 mRNA and protein are highly expressed within the cytoplasm of growing oocytes. The Clast4 protein is stable during this developmental window and post-translationally modified by phosphorylation upon oocyte meiotic maturation. Additionally, we show that Clast4 and eIF4E directly interact by means of a canonical and functional eIF4E-binding motif. Our results suggest that Clast4, similar to Drosophila Cup, may act at the translational level during murine female germ-line development.
|
|
Mutations |
3 mutations
Species: human
Mutation name: None
type: naturally occurring
fertility: subfertile
Comment: Mutations in eIF4ENIF1 Are Associated With Primary Ovarian Insufficiency. Kasippillai T 2013 et al.
Context:Primary ovarian insufficiency (POI), or premature ovarian failure, results from ovarian follicle depletion with a consequent elevation of FSH levels before age 40 years. We identified a family in which 9 women in 3 consecutive generations developed menopause at approximately age 30 years. We hypothesized a genetic cause with a dominant mode of inheritance.Design:This was a family-based genetic study and a replicate group of women with POI.Setting:The study was conducted at an academic medical center.Patients:Seven affected women and an obligate carrier and 7 unaffected family members were genotyped. The genes of interest were also sequenced in 38 unrelated women with POI.Intervention:The DNA from 7 family members was subjected to whole-exome sequencing. The genotypes of interest were confirmed and genotypes of additional family members and unrelated women with POI were determined using Sanger sequencing.Main Outcome Measure:A high-impact, deleterious variant that segregated appropriately with POI in the family was measured.Results:A heterozygous stop codon (Ser429X) was identified in the eukaryotic translation initiation factor 4E nuclear import factor 1 (eIF4ENIF1) in the proband and all affected women but not in the unaffected family members. The chance that such a high-impact, deleterious variant would segregate appropriately among the affected and unaffected relatives by chance is very low (P < .05). There were no additional mutations identified in eIF4ENIF1 or eIF4E in 38 unrelated women with POI.Conclusion:Data demonstrate a new gene associated with dominantly inherited POI. These results highlight the importance of translation initiation factors and their regulators in ovarian function.
/////////////////////////
Species: D. melanogaster
Mutation name:
type: null mutation
fertility: infertile - ovarian defect
Comment: Cup is a nucleocytoplasmic shuttling protein that interacts with the eukaryotic translation initiation factor 4E to modulate Drosophila ovary development. Zappavigna V et al. (2004) In Drosophila, the product of the fs (2)cup gene (Cup) is known to be crucial for diverse aspects of female germ-line development. Its functions at the molecular level, however, have remained mainly unexplored. Cup was found to directly associate with eukaryotic translation initiation factor 4E (eIF4E). In this report, we show that Cup is a nucleocytoplasmic shuttling protein and that the interaction with eIF4E promotes retention of the Cup protein in the cytoplasm. Cup is required for the correct accumulation and localization of eIF4E within the posterior cytoplasm of developing oocytes. We furthermore show that cup and eIF4E interact genetically, because a reduction in the level of eIF4E activity deteriorates the development and growth of ovaries bearing homozygous cup mutant alleles. Our results reveal a crucial role for the Cup-eIF4E complex in ovary-specific developmental programs.//////////////////
Species: mouse
Mutation name:
type: null mutation
fertility: infertile - ovarian defect
Comment: Clast4, the murine homologue of human eIF4E-Transporter, is highly expressed in developing oocytes and post-translationally modified at meiotic maturation. Villaescusa JC et al. (2006) In metazoans, translational regulation of a set of maternal mRNAs directs oocyte maturation and early embryogenesis. These transcripts are often kept dormant until their products are spatially and temporally required in development. The interaction between general translation factors (i.e. eIF4E) and their specific interactors influences translation initiation. A search of the protein database for a mouse homologue of the Drosophila Cup protein, a translational repressor during female germ-line development, identified the product of the Clast4 gene. In this report, we show that Clast4 mRNA and protein are highly expressed within the cytoplasm of growing oocytes. The Clast4 protein is stable during this developmental window and post-translationally modified by phosphorylation upon oocyte meiotic maturation. Additionally, we show that Clast4 and eIF4E directly interact by means of a canonical and functional eIF4E-binding motif. Our results suggest that Clast4, similar to Drosophila Cup, may act at the translational level during murine female germ-line development.//////////////////
|