Species: mouse
Mutation name:
type: null mutation
fertility: infertile - ovarian defect
Comment: The subcortical maternal complex controls symmetric division of mouse zygotes by regulating F-actin dynamics. Yu XJ et al. (2014) Maternal effect genes play critical roles in early embryogenesis of model organisms where they have been intensively investigated. However, their molecular function in mammals remains largely unknown. Recently, we identified a subcortical maternal complex (SCMC) that contains four proteins encoded by maternal effect genes (Mater, Filia, Floped and Tle6). Here we report that TLE6, similar to FLOPED and MATER, stabilizes the SCMC and is necessary for cleavage beyond the two-cell stage of development. We document that the SCMC is required for formation of the cytoplasmic F-actin meshwork that controls the central position of the spindle and ensures symmetric division of mouse zygotes. We further demonstrate that the SCMC controls formation of the actin cytoskeleton specifically via Cofilin, a key regulator of F-actin assembly. Our results provide molecular insight into the physiological function of TLE6, its interaction with the SCMC and their roles in the symmetric division of the zygote in early mouse development. ​Tle6 Null mice are sterile, and the protein product of ​Tle6 is required for formation of SCMC in mouse oocytes and early embryos. Most importantly, we document a role for the SCMC as an oocyte–embryo-specific protein complex that controls symmetric division of mouse zygotes by regulating the actin cytoskeleton through Cofilin.

Species: human
Mutation name:
type: naturally occurring
fertility: embryonic lethal
Comment: TLE6 mutation causes the earliest known human embryonic lethality. Alazami AM et al. (2015) Embryonic lethality is a recognized phenotypic expression of individual gene mutations in model organisms. However, identifying embryonic lethal genes in humans is challenging, especially when the phenotype is manifested at the preimplantation stage. In an ongoing effort to exploit the highly consanguineous nature of the Saudi population to catalog recessively acting embryonic lethal genes in humans, we have identified two families with a female-limited infertility phenotype. Using autozygosity mapping and whole exome sequencing, we map this phenotype to a single mutation in TLE6, a maternal effect gene that encodes a member of the subcortical maternal complex in mammalian oocytes. Consistent with the published phenotype of mouse Tle6 mutants, embryos from female patients who are homozygous for the TLE6 mutation fail to undergo early cleavage, with resulting sterility. The human mutation abrogates TLE6 phosphorylation, a step that is reported to be critical for the PKA-mediated progression of oocyte meiosis II. Furthermore, the TLE6 mutation impairs its binding to components of the subcortical maternal complex. In this first report of a human defect in a member of the subcortical maternal subcritical maternal complex, we show that the TLE6 mutation is gender-specific and leads to the earliest known human embryonic lethality phenotype.//////////////////

Species: human
Mutation name:
type: naturally occurring
fertility: infertile - ovarian defect
Comment: Novel mutations in genes encoding subcortical maternal complex proteins may cause human embryonic developmental arrest. Wang X et al. (2018) Successful human reproduction initiates from normal gamete formation, fertilization and early embryonic development. Abnormalities in any of these steps will lead to infertility. Many infertile patients undergo several failures of IVF and intracytoplasmic sperm injection (ICSI) cycles, and embryonic developmental arrest is a common phenotype in cases of recurrent failure of IVF/ICSI attempts. However, the genetic basis for this phenotype is poorly understood. The subcortical maternal complex (SCMC) genes play important roles during embryonic development, and using whole-exome sequencing novel biallelic mutations in the SCMC genes TLE6, PADI6 and KHDC3L were identified in four patients with embryonic developmental arrest. A mutation in TLE6 was found in a patient with cleaved embryos that arrested on day 3 and failed to form blastocysts. Two patients with embryos that arrested at the cleavage stage had mutations in PADI6, and a mutation in KHDC3L was found in a patient with embryos arrested at the morula stage. No mutations were identified in these genes in an additional 80 patients. These findings provide further evidence for the important roles of TLE6, PADI6 and KHDC3L in embryonic development. This work lays the foundation for the genetic diagnosis of patients with recurrent IVF/ICSI failure.//////////////////

Species: human
Mutation name:
type: naturally occurring
fertility: infertile - ovarian defect
Comment: A novel TLE6 mutation, c.541+1G>A, identified using whole-exome sequencing in a Chinese family with female infertility. Mao B et al. (2021) Oocytes have a lot of maternal RNAs and proteins, which are used by the early embryo before zygotic genome activation. Transducin-like enhancer of split 6 (TLE6) is a component of a subcortical maternal complex which plays a critical role in early embryonic development. The patient had been diagnosed with primary infertility for 6 years and had undergone multiple failed in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles. Genomic DNA samples were extracted from her parents' peripheral blood as well as hers. Whole-exome sequencing and Sanger validation were performed to identify candidate variants. We identified a novel transducin-like enhancer of split 6 (TLE6) gene mutations in the female patient with recurrent IVF/ICSI failure. The patient carried a homozygous mutation (NM_001143986.1(TLE6): c.541+1G>A) and had viable but low-quality embryos. Her parents both had heterozygous mutations at this locus. Our study expands the mutational and phenotypic spectrum of TLE6 and suggests the important role of TLE6 during embryonic development. Our findings have implications for the genetic diagnosis of female infertility with recurrent IVF/ICSI failure.//////////////////