Related Experiment Video
Updated: Jul 31, 2026
Generation of Genetically Modified Mice through the Microinjection of Oocytes
Published on: June 15, 2017
Mice with a homozygous gene trap vector insertion in mgcRacGAP die during pre-implantation development
T Van de Putte1, A Zwijsen, O Lonnoy
1Department of Cell Growth, Differentiation and Development (VIB-07), Flanders Interuniversity Institute for Biotechnology (VIB) and Laboratory of Molecular Biology (CELGEN), University of Leuven, Herestraat 49, 3000, Leuven, Belgium.
Abstract:
In a phenotypic screen in mice using a gene trap approach in embryonic stem cells, we have identified a recessive loss-of-function mutation in the mgcRacGAP gene. Maternal protein is present in the oocyte, and mgcRacGAP gene transcription starts at the four-cell stage and persists throughout mouse pre-implantation development. Total mgcRacGAP deficiency results in pre-implantation lethality. Such E3.5 embryos display a dramatic reduction in cell number, but undergo compaction and form a blastocoel. At E3.0-3.5, binucleated blastomeres in which the nuclei are partially interconnected are frequently observed, suggesting that mgcRacGAP is required for normal mitosis and cytokinesis in the pre-implantation embryo. All homozygous mutant blastocysts fail to grow out on fibronectin-coated substrates, but a fraction of them can still induce decidual swelling in vivo. The mgcRacGAP mRNA expression pattern in post-implantation embryos and adult mouse brain suggests a role in neuronal cells. Our results indicate that mgcRacGAP is essential for the earliest stages of mouse embryogenesis, and add evidence that CYK-4-like proteins also play a role in microtubule-dependent steps in the cytokinesis of vertebrate cells. In addition, the severe phenotype of null embryos indicates that mgcRacGAP is functionally non-redundant and cannot be substituted by other GAPs during early cleavage of the mammalian embryo.
Insights
mgcRacGAP is essential for early mouse development, with its loss causing pre-implantation lethality due to failed mitosis and cytokinesis. This gene is crucial and cannot be compensated for by other GAPs.
Area of Science:
- Developmental Biology
- Cell Biology
- Genetics
Background:
- The earliest stages of mammalian embryonic development are critical for successful reproduction.
- Proper cell division, including mitosis and cytokinesis, is fundamental for embryonic development.
- Rho GTPase-activating proteins (GAPs) regulate cell division, but their specific roles in early mammalian embryogenesis are not fully understood.
Purpose of the Study:
- To investigate the function of the mgcRacGAP gene during mouse pre-implantation development.
- To determine the consequences of mgcRacGAP loss-of-function on early embryonic cell division.
- To elucidate the role of mgcRacGAP in mitosis and cytokinesis in the mammalian embryo.
Main Methods:
- Phenotypic screening in mice using a gene trap approach in embryonic stem cells.
- Analysis of mgcRacGAP gene transcription and protein presence.
- Examination of embryonic development stages (E3.0-E3.5) and blastocyst growth.
- In vivo assessment of decidual swelling.
Main Results:
- A recessive loss-of-function mutation in mgcRacGAP was identified, leading to pre-implantation lethality.
- mgcRacGAP-deficient embryos showed reduced cell numbers and frequent binucleated blastomeres, indicating defects in mitosis and cytokinesis.
- Homozygous mutant blastocysts failed to grow on fibronectin, but some induced decidual swelling in vivo.
- mgcRacGAP mRNA is expressed in post-implantation embryos and adult brain, suggesting broader roles.
Conclusions:
- mgcRacGAP is essential for normal mitosis and cytokinesis during mouse pre-implantation development.
- The severe phenotype of null embryos highlights the functional non-redundancy of mgcRacGAP, which cannot be substituted by other GAPs.
- mgcRacGAP is vital for the earliest stages of mammalian embryogenesis, with potential roles in neuronal cells.
