Biology subjects

Basanta, S.

Publications and source records attributed to Basanta, S..

2 recordsLinked to original sources

bioRxiv2024

Hallmarks of uterine receptivity predate placental mammals

Embryo implantation is essential to pregnancy in eutherian (placental) mammals. The cellular changes that enabled invasive implantation to evolve from superficial embryo apposition, the ancestral condition still retained in marsupials, have remained unclear. We generated and compared single-cell transcriptomes from the peri-implantation and non-pregnant uterus of two rodents with invasive implantation, the mouse and the guinea pig, and the opossum, a marsupial lacking invasive implantation. Cross-species analysis of endometrial cell types and ligand-receptor signaling revealed that the opossum blastocyst-stage uterus, despite lacking fetal-maternal contact, shares key features with the eutherian window of receptivity. These include a window in which the epithelial-stromal IHH-PTCH1 axis is active, but the downstream BMP2-mediated signaling that enables decidualization in eutherians is antagonized through a temporary spike in glandular GREM2. We propose that a homologous progesterone-responsive endometrial remodeling reaction preceded the evolution of eutherian and marsupial modes of implantation in their respective lineages. Complementary analysis of pre- and post-implantation embryonic transcriptomes from the same species revealed broad conservation of implantation-related functional genes in the blastocyst, as well as a remarkable similarity in ligand production between the mature trophoblast and the luminal epithelium. We suggest that this redundancy between trophectoderm and luminal epithelial signaling was an enabling factor for the evolution of invasive placentation. Together, these findings suggest that eutherian implantation evolved by maternal rewiring of the output of an ancestral window of receptivity-like epithelial-stromal signaling axis toward decidualization, stabilized epithelial loss, and invasion. Significance StatementPregnancy in placental mammals begins with implantation and invasion of the embryo, whereas marsupials retain a superficial mode of embryo apposition. How this major evolutionary transition occurred is unknown. Comparing uterine and embryonic single-cell transcriptomes between model rodents and the opossum reveals that the marsupial uterus activates an epithelial-stromal signaling axis canonically associated with receptivity to implantation. In the marsupial uterus, its outputs are opposed by inhibitory signals, whereas in placental mammals, this program promotes uterine decidual transformation and invasion. Early-embryo implantation-related gene expression, in contrast, shows little change across species. These results challenge the view that implantation evolved through the gain of invasive properties by the embryo, and reveal a common developmental foundation from which placentals evolved their novel mode of gestation.

evolutionary biology↗

bioRxiv2024

Comparative single cell analysis reveals complex patterns of cell type and cell signaling innovations at the fetal-maternal interface

How fetal and maternal cell types have co-evolved to enable mammalian placentation poses a unique evolutionary puzzle. Here, we present a multi-species atlas integrating single-cell transcriptomes from six species bracketing therian mammal diversity. We find that invasive trophoblasts share a gene-expression signature across eutherians, and evidence that endocrine decidual cells evolved stepwise from an immunomodulatory cell type retained in Tenrec with affinity to human decidua of menstruation. We recover evolutionary patterns in ligand-receptor signaling: fetal and maternal cells show a pronounced tendency towards disambiguation, but a predicted arms race dynamic between them is limited. We reconstruct cell communication networks of extinct mammalian ancestors, finding strong integration of fetal trophoblast into maternal networks. Together, our results reveal a dynamic history of cell type and signaling evolution. SynopsisThe fetal-maternal interface is one of the most intense loci of cell-cell signaling in the human body. Invasion of cells from the fetal placenta into the uterus, and the corresponding transformation of maternal tissues called decidualization, first evolved in the stem lineage of eutherian mammals(1, 2). Single-cell studies of the human fetal-maternal interface have provided new insight into the cell type diversity and cell-cell interactions governing this chimeric organ(3-5). However, the fetal-maternal interface is also one of the most rapidly evolving, and hence most diverse, characters among mammals(6), and an evolutionary analysis is missing. Here, we present and compare single-cell data from the fetal-maternal interface of species bracketing key events in mammal phylogeny: a marsupial (opossum, Monodelphis domestica), the afrotherian Tenrec ecaudatus, and four Euarchontoglires - guinea pig and mouse (Rodentia) together with recent macaque and human data (primates) (4, 5, 7). We infer cell type homologies, identify a gene-expression signature of eutherian invasive trophoblast conserved over 99 million years, and discover a predecidual cell in the tenrec which suggests stepwise evolution of the decidual stromal cell. We reconstruct ancestral cell signaling networks, revealing the integration of fetal cell types into the interface. Finally, we test two long-standing theoretical predictions, the disambiguation hypothesis(8) and escalation hypothesis(9), at transcriptome-wide scale, finding divergence between fetal and maternal signaling repertoires but arms race dynamics restricted to a small subset of ligand-receptor pairs. In so doing, we trace the co-evolutionary history of cell types and their signaling across mammalian viviparity.

evolutionary biology↗