Biology subjects

Shannon, M. J.

Publications and source records attributed to Shannon, M. J..

7 recordsLinked to original sources

bioRxiv2025

Low oxygen promotes extravillous trophoblast progenitor expansion but restrains maturation

Placental development occurs in a low oxygen environment, yet how oxygen tension instructs differentiation of progenitor cytotrophoblasts (CTB) along the extravillous versus villous pathways remains incompletely understood. In particular, the role of low oxygen in early extravillous trophoblast (EVT) progenitor expansion and subsequent maturation has been difficult to assess due to the lack of models allowing sequential, high-resolution characterization. Using human trophoblast organoids and single-cell transcriptomics, we examined the effects of ambient (21%) and physiological (2-3%, 8%) oxygen on EVT and SCT differentiation. We show that low oxygen promotes the initial expansion of column CTB-like progenitors but restricts terminal EVT maturation. Conversely, we show that ambient oxygen drives the formation of EVT and syncytiotrophoblast. Stabilization of HIF-1 partially recapitulates the EVT maturation block but does not contribute to EVT progenitor expansion, indicating HIF-dependent and-independent contributions. These findings clarify how oxygen shapes EVT lineage progression and define HIF-1s role in coordinating progenitor expansion versus maturation.

developmental biology↗

bioRxiv2025

A blastocyst-derived in vitro model of the human chorion

The placenta supports the foetus by mediating nutrient and gas exchange, hormone production, and immune protection. Yet, human placental biology remains poorly understood due to limited in vitro models. The foetal part of the placenta, the chorion, consists of a trophoblast-derived layer and a mesenchymal zone containing extraembryonic mesoderm cells. Here, we show that human blastocysts can give rise to both trophoblast organoids and extraembryonic mesoderm cells under the same culture conditions. Trophoblast organoids originate from both outer trophoblast cells and inner cells of the blastocyst, while extraembryonic mesoderm cells derive exclusively from inner cells. These organoids recapitulate the cellular composition, morphology, and function of the in vivo trophoblast. Moreover, given the high rate of aneuploidy at the blastocyst stage, aneuploid trophoblast organoids can be readily generated. These models reflect the trophoblasts unique ability to tolerate aneuploidy and offer a valuable platform to study human placental development and pathophysiology.

developmental biology↗

bioRxiv2024

RNA sequencing reveals the developmental onset of autosomal gene expression differences in male and female extravillous trophoblasts

BackgroundThe human placenta is an essential organ for fetal development and pregnancy success. Across gestation, blastocyst-derived trophoblasts facilitate the major functions of the placenta. Specifically, invasive trophoblast subtypes, called extravillous trophoblasts (EVT), play central roles in coordinating nutrient accessibility and maternal immunomodulation to semi-allogeneic fetal and placental tissues. Like the fetus, these trophoblasts can be chromosomally male (XY) or female (XX). While male and female trophoblasts are associated with distinct placental gene signatures, specific differences between male and female EVT have not been defined across the first trimester. MethodsTo understand how male and female EVT differ, we subjected male and female first trimester EVT cell preparations to bulk RNA sequencing. Concurrently, publicly available single-cell RNA sequencing datasets of first trimester placental and decidual tissues were utilized to resolve EVT differentiation and EVT subtype-specific sex differences. Candidate genes were then selected and immuno-localized to specific regions and cell populations in male and female placentas. ResultsWe found that before week 10 of gestation, both male and female EVT lineage cells increase expression of transcripts associated with cell proliferation. Sex-related gene differences within this early developmental time-point are restricted to genes residing on sex chromosomes. Following week 10 of gestation, there is a broad up-regulation of genes linked to immunoregulation in male and female EVT. However, within this later developmental period, autosomal gene differences appear in relation to biological sex. We go on to show that these sex-dependent autosomal gene differences influence EVT-maternal cell signalling within the uterus whereby pregnancies exposed to a male placenta demonstrate more complex MIF and CD99 as well as angiogenesis-associated VEGF cell-cell signals between male EVT and the female maternal immune and non-immune cells found throughout the uterus. ConclusionsThese findings resolve early first trimester EVT lineage trophoblast sex differences and highlight a developmental timepoint that is critical to male and female autosomal gene expression. HIGHLIGHTSO_LIFirst trimester male and female placenta cells were compared using bulk and single-cell transcriptomics C_LIO_LIGestational age and placental sex are the leading drivers of variation in gene expression C_LIO_LISex-related differences in autosomal genes generally arise on week 10 of gestation C_LIO_LISex-related differences in trophoblast and uterine cell crosstalk are driven by autosomal gene differences arising after week 10 of gestation C_LI PLAIN ENGLISH SUMMARYThe human placenta is a temporary organ that forms during pregnancy. Importantly, the placenta acts as a surrogate for not yet functioning fetal organ systems (i.e., the heart, lungs, and kidneys) while they mature within the fetus. Because the placenta develops from cells of the early embryo, it can be biologically male or female. Male and female placentas are genetically different from each other, where these differences may differentially influence placental functions and pregnancy health through unknown mechanisms. Therefore, this study aimed to understand how male and female placenta cells differ at the level of gene expression. We find that on week 10 of gestation, but not before, female placenta cells express a different repertoire of genes compared to male placenta cells. We show that these differences potentially affect how cells of the placenta and uterus interact with each other. Taken together, these results identify a developmental timepoint in pregnancy where the biological sex of the placenta may instruct subtle differences in how male or female placenta cells communicate with the maternal compartment in pregnancy. Summary StatementBulk and single-cell RNA sequencing provides comprehensive comparison between uncultured male and female HLA-G-purified trophoblasts derived from first-trimester human placentas.

developmental biology↗

bioRxiv2024

PAG orchestrates T cell immune synapse function by binding to actin

Many immunotherapies impact T cell function by impacting the immune synapse. While immunotherapy is extremely successful in some patients, in many others, it fails to help or causes complications, including immune-related adverse events. Phosphoprotein Associated with Glycosphingolipid Rich Microdomains 1 (PAG) is a transmembrane scaffold protein with importance in T cell signaling. PAG has 10 tyrosine phosphorylation sites where many kinases and phosphatases bind. PAG is palmitoylated, so it localizes in lipid rafts of the membrane, and contains a C-terminal PDZ domain to link to the actin cytoskeleton. As a link between signaling-protein-rich membrane regions and the actin cytoskeleton, PAG is an exciting and novel target for manipulating immune function. Here, we sought to determine if PAG works with actin to control T cell synapse organization and function. We found that PAG and actin dynamics are tightly coordinated during synapse maturation. A PDZ domain mutation disrupts the PAG-actin interaction, significantly impairing synapse formation, stability, and function. To assess the impact of the PDZ mutation functionally in vivo, we employed a mouse model of type IV hypersensitivity and an OVA-tumor mouse model. In both systems, mice with T cells expressing PDZ-mutant PAG had diminished immune responses, including impaired cytotoxic function. These findings highlight the importance of the PAG-actin link for effective T cell immune synapse formation and function. The results of our study suggest that targeting PAG is a promising approach for modulating immune responses and treating immune-related diseases. One Sentence SummaryAdaptor protein PAG links to the actin cytoskeleton, and this link is essential for T cell synapse formation and cytotoxic function.

immunology↗

bioRxiv2023

Modulation of NK cell migration by IL-15 defined using a new tool for data-driven clustering of heterogeneous cell behaviour trajectories

Advances in imaging, cell segmentation, and cell tracking now routinely produce microscopy datasets of a size and complexity comparable to transcriptomics or proteomics. New tools are required to process this phenomics type data. Cell PLasticity Analysis TOol (cellPLATO) is a Python-based analysis software designed for measurement and classification of diverse cell behaviours based on clustering of parameters of cell morphology and motility. cellPLATO is used after segmentation and tracking of cells from live cell microscopy data. The tool extracts morphological and motility metrics from each cell per timepoint, before being using them to segregate cells into behavioural subtypes with dimensionality reduction. Resultant cell tracks have a behavioural ID for each cell per timepoint corresponding to their changing behaviour over time in a sequence. Similarity analysis allows the grouping of behavioural sequences into discrete trajectories with assigned IDs. Trajectories and underlying behaviours generate a phenotypic finger-print for each experimental condition, and representative cells are mathematically identified and graphically displayed for human understanding of each subtype. Here, we use cellPLATO to investigate the role of IL-15 in modulating NK cell migration on ICAM-1 or VCAM-1. We find 8 behavioural subsets of NK cells based on their shape and migration dynamics, and 4 trajectories of behaviour. Therefore, using cellPLATO we show that IL-15 increases plasticity between cell migration behaviours and that different integrin ligands induce different forms of NK cell migration.

cell biology↗

bioRxiv2022

Single-cell assessment of trophoblast stem cell-based organoids as human placenta-modeling platforms

The recent discovery of human trophoblast stem cells (hTSC) and techniques allowing for trophoblast organoid (TOrg) culture have established promising approaches for studying human trophoblast development. To validate the accuracy of these models at single-cell resolution, we directly compared in vitro TOrg cultures derived from primary progenitor cytotrophoblasts (CTB) or commercially available hTSC lines to in vivo human trophoblasts using a scRNA-seq approach. While patient-derived (PD)- and hTSC-derived TOrgs overall reflect cell differentiation trajectories with accuracy, specific features related to trophoblast state make-up, distinct sub-paths of differentiation, and predicted transcriptional drivers regulating stem cell maintenance were shown to be misaligned in the in vitro platforms. This is best exemplified by the identification of a distinct progenitor state in hTSC-derived TOrgs that showed characteristics of CTB- and extravillous-like cell states. Together, this work provides a comprehensive resource that identifies underlying strengths and limitations of current TOrg platforms. Summary StatementSingle-cell transcriptomics provides comprehensive comparison between trophoblast organoids derived from commercially available trophoblast stem cells and first-trimester primary human cytotrophoblasts. HIGHLIGHTSO_LIAn integrated single cell transcriptomic atlas of placental and organoid trophoblasts establishes a comprehensive and public web-based resource C_LIO_LIDirect comparison of trophoblasts from placental/decidual tissue to trophoblasts extracted from two distinct organoid platforms highlights both conserved and divergent features C_LIO_LIComputational modeling describes novel trophoblast states and routes of cell differentiation in human trophoblast organoids C_LI IN BRIEFWhile the merits and utility of current trophoblast organoid cultures have been established, high-resolution assessment and comparison of conserved and divergent features of these systems to cell states and differentiation trajectories of trophoblasts in situ or in vitro has not been performed. Here, Shannon et al. generate a single-cell transcriptomic atlas of two trophoblast organoids that comprehensively define the similarities and discrepancies in relation to trophoblasts from the placental-maternal interface.

developmental biology↗

bioRxiv2022

Transcriptomic mapping of the metzincin landscape in human trophoblasts

The metzincin family of metalloproteases coordinates cell and tissue developmental processes through regulation of growth factor availability, receptor signaling, and cell-cell/cell-matrix adhesion. During placental development, while distinct roles for metzincin proteases in controlling specific trophoblast functions have been described, a comprehensive assessment of metzincins during discrete stages of trophoblast differentiation has yet to be performed. Here we provide a comprehensive single cell transcriptomic resource of metzincin protease expression in diverse states of human trophoblasts from first trimester placental and decidual tissues. In the 8 distinct trophoblasts states categorized [four progenitor cytotrophoblast (CTB), one syncytiotrophoblast precursor (SCTp), two column CTB (cCTB), and one extravillous trophoblast (EVT) state], we identified 24 metzincin genes. These included 12 adamalysins, 2 pappalysins, 3 astacins and 7 matrixins. Cell trajectory modeling shows that expression of most (19/24) metzincins increases across CTB to EVT differentiation, though select proteases also increase as CTB fuse into syncytiotrophoblast. Within the CTB niche, single-cell velocity ordering identified 11 metzincins (ADAM10, -17, MMP14, -15, -19, -23B, ADAMTS1, -6, -19, TLL-1, -2) expressed in progenitors proximal to the predicted origin. Analysis of metzincin-substrate interactions within the CTB niche revealed [~]150 substrates and binding partners, including FBN2 as an ADAMTS6-specific substrate preferentially expressed in trophoblast progenitors. Together, this work characterizes the metzincin transcriptomic landscape in human first trimester trophoblasts and establishes insight into the roles specific proteases perform within distinct trophoblast niches and across differentiation. This resource serves as a guide for future investigations into the roles of metzincin proteases in human placental development. Summary StatementSingle cell RNA sequencing characterizes the expression of multiple metzincin proteases within first trimester placental trophoblasts. Examination of protease-substrate interactions within cytotrophoblasts identifies potential interactions between ADAMTS6 and FBN2. HighlightsO_LISingle cell RNA sequencing identifies 24 distinct metzincin proteases expressed in human first trimester trophoblasts C_LIO_LILineage trajectory modelling shows that metzincin genes are dynamic and likely control processes in progenitor, mid-point, and end-point states of trophoblast differentiation. C_LIO_LIADAMTS6, and its putative substrate FBN2, localize specifically to progenitor trophoblasts C_LI

developmental biology↗