Cell type and cell signalling innovations underlying mammalian pregnancy

Area of Science:

• Evolutionary biology
• Developmental biology
• Genomics

Background:

• Mammalian placentation involves complex interactions between fetal and maternal cells.
• Understanding the co-evolution of these cell types is crucial for deciphering placental development.

Purpose of the Study:

• To investigate the evolutionary history and co-evolution of fetal and maternal cell types during mammalian placentation.
• To identify conserved and novel cell types and signaling pathways at the fetal-maternal interface.

Main Methods:

• Comparative single-cell transcriptomics across six mammalian species (opossum, tenrec, mouse, guinea pig, macaque, human).
• Bioinformatic analysis to identify conserved transcriptomic signatures and reconstruct cell-cell communication networks.

Main Results:

• Identified a conserved transcriptomic signature of invasive trophoblast in eutherians, linked to haemochorial placentation.
• Revealed that the maternal decidual cell evolved from an immunomodulatory predecidual cell type.
• Observed a tendency towards exclusive ligand expression in fetal-maternal cell signaling, with limited evidence of co-evolutionary 'arms races'.
• Reconstructed ancestral uteroplacental communication networks, showing signaling innovations and integration.

Conclusions:

• Mammalian placentation is shaped by dynamic co-evolution of fetal and maternal cell types.
• Specific cell types and signaling pathways have evolved to facilitate placental development and function.
• Comparative transcriptomics provides insights into the evolutionary history of the maternal-fetal interface.