Disruption of Folate Metabolism Causes Poor Alignment and Spacing of Mouse Conceptuses for Multiple Generations

• Published in: Frontiers in cell and developmental biology Vol. 9; p. 723978
• Main Authors: Wilkinson, Amy L, Menelaou, Katerina, Rakoczy, Joanna, Tan, Xiu S, Watson, Erica D
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 10-12-2021
• Subjects: Cell and Developmental Biology; decidua; grandparental effect; MTRR; transgenerational epigenetic inheritance; trophoblast; twinning; twinning; conceptus misalignment; transgenerational epigenetic inheritance; MTRR; decidua; grandparental effect; trophoblast
• ISSN: 2296-634X; 2296-634X
• DOI: 10.3389/fcell.2021.723978

Abnormal uptake or metabolism of folate increases risk of human pregnancy complications, though the mechanism is unclear. Here, we explore how defective folate metabolism influences early development by analysing mice with the hypomorphic
mutation. MTRR is necessary for methyl group utilisation from folate metabolism, and the
allele disrupts this process. We show that the spectrum of phenotypes previously observed in
conceptuses at embryonic day (E) 10.5 is apparent from E8.5 including developmental delay, congenital malformations, and placental phenotypes. Notably, we report misalignment of some
conceptuses within their implantation sites from E6.5. The degree of misorientation occurs across a continuum, with the most severe form visible upon gross dissection. Additionally, some
conceptuses display twinning. Therefore, we implicate folate metabolism in blastocyst orientation and spacing at implantation. Skewed growth likely influences embryo development since developmental delay and heart malformations (but not defects in neural tube closure or trophoblast differentiation) associate with severe misalignment of
conceptuses. Typically, the uterus is thought to guide conceptus orientation. To investigate a uterine effect of the
allele, we manipulate the maternal
genotype. Misaligned conceptuses were observed in litters of
,
, and
mothers. While progesterone and/or BMP2 signalling might be disrupted, normal decidual morphology, patterning, and blood perfusion are evident at E6.5 regardless of conceptus orientation. These observations argue against a post-implantation uterine defect as a cause of conceptus misalignment. Since litters of
mothers display conceptus misalignment, a grandparental effect is explored. Multigenerational phenotype inheritance is characteristic of the
model, though the mechanism remains unclear. Genetic pedigree analysis reveals that severe conceptus skewing associates with the
genotype of either maternal grandparent. Moreover, the presence of conceptus skewing after embryo transfer into a control uterus indicates that misalignment is independent of the peri- and/or post-implantation uterus and instead is likely attributed to an embryonic mechanism that is epigenetically inherited. Overall, our data indicates that abnormal folate metabolism influences conceptus orientation over multiple generations with implications for subsequent development. This study casts light on the complex role of folate metabolism during development beyond a direct maternal effect.