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Nhlrc2 is crucial during mouse gastrulation
Anniina E Hiltunen1, Reetta Vuolteenaho2, Veli-Pekka Ronkainen2
1Medical Research Center Oulu and PEDEGO Research Unit, University of Oulu and Oulu University Hospital, Oulu, Finland.
Abstract:
The loss of NHL repeat containing 2 (Nhlrc2) leads to early embryonic lethality in mice, but the exact timing is currently unknown. In this study, we determined the time of lethality for Nhlrc2 knockout (KO), C57BL/6NCrl-Nhlrc2tm1a(KOMP)Wtsi /Oulu, embryos and the in situ expression pattern of Nhlrc2 based on LacZ reporter gene expression during this period. Nhlrc2 KO preimplantation mouse embryos developed normally after in vitro fertilization. Embryonic stem (ES) cells established from KO blastocysts proliferated normally despite a complete loss of the NHLRC2 protein. Nhlrc2 KO embryos from timed matings implanted and were indistinguishable from their wildtype littermates on embryonic day (E) 6.5. On E7.5, Nhlrc2 KO embryo development was arrested, and on E8.5, only 6% of the genotyped embryos were homozygous for the Nhlrc2tm1a(KOMP)Wtsi allele. Nhlrc2 KO E8.5 embryos showed limited embryonic or extraembryonic tissue differentiation and remained at the cylinder stage. Nhlrc2 expression was ubiquitous but strongest in the epiblast/ectoderm and extraembryonic ectoderm on E6.5 and E7.5. NHLRC2 is essential for early postimplantation development, and its loss leads to failed gastrulation and amniotic folding in mice. Future studies on the evolutionarily conserved NHLRC2 will provide new insights into the molecular pathways involved in the early steps of postimplantation development.
Insights
Loss of NHL repeat containing 2 (Nhlrc2) causes early embryonic lethality in mice, with development arrested by embryonic day 7.5. This essential gene is crucial for gastrulation and amniotic folding during postimplantation development.
Area of Science:
- Developmental Biology
- Genetics
- Molecular Biology
Background:
- NHL repeat containing 2 (Nhlrc2) is essential for mammalian development, but its precise role and the timing of lethality in its absence are not fully understood.
- Previous studies indicate that Nhlrc2 loss leads to embryonic lethality, necessitating a detailed examination of its function during early embryogenesis.
Purpose of the Study:
- To determine the exact timing of embryonic lethality in Nhlrc2 knockout (KO) mice.
- To investigate the in situ expression pattern of Nhlrc2 during the critical period of early postimplantation development.
Main Methods:
- Generation and analysis of Nhlrc2 knockout mouse embryos using CRISPR/Cas9 technology.
- In vitro fertilization and embryo culture to assess preimplantation development.
- LacZ reporter gene expression analysis to map Nhlrc2 expression patterns.
- Genotyping and morphological assessment of embryos at various developmental stages (E6.5, E7.5, E8.5).
Main Results:
- Nhlrc2 KO preimplantation embryos and derived embryonic stem cells developed normally.
- Postimplantation Nhlrc2 KO embryos showed normal development until embryonic day 6.5.
- Developmental arrest occurred by embryonic day 7.5, with significant lethality by E8.5.
- Nhlrc2 expression was widespread, with highest levels in epiblast/ectoderm and extraembryonic ectoderm on E6.5-E7.5.
- KO embryos exhibited failed gastrulation and amniotic folding, remaining at the cylinder stage.
Conclusions:
- NHLRC2 is indispensable for successful early postimplantation development in mice.
- Loss of NHLRC2 function disrupts critical developmental processes including gastrulation and amniotic fold formation.
- Further research into the evolutionarily conserved NHLRC2 will elucidate molecular pathways governing early mammalian development.
