Biology subjects

Lupu, I.-E.

Publications and source records attributed to Lupu, I.-E..

5 recordsLinked to original sources

bioRxiv2025

Essential regulation of heparan sulfate proteoglycan signalling controls cell behaviour to support cardiac development

Heparan sulfate proteoglycan (HSPG)-dependent signalling is essential for cardiac development, yet how HSPGs are regulated in the forming heart is unknown. Here, we show that the extracellular heparan sulfate modifier, SULF1, expressed by the epicardium, dynamically regulates HSPG sulfation to fine-tune the magnitude and duration of signalling to impact cell fate and cardiac morphogenesis. Single cell genomics and lineage tracing studies reveal Sulf1 to be strongly co-expressed with Wt1 in the epicardium, with reduction of both coinciding with epithelial-mesenchymal transition and quiescence. CUT&RUN-seq revealed transcriptional control of Sulf1 by WT1 which directly impacts essential HSPG-dependent downstream signalling. Our study highlights, for the first time, essential fine-tuning of HSPG-dependent signalling to modulate key processes for heart formation.

developmental biology↗

bioRxiv2022

Lymphatic endothelium arises directly from specialized angioblasts

The lymphatic vasculature is essential for tissue fluid homeostasis, immune cell surveillance and dietary lipid absorption, and has emerged as a key regulator of organ growth and repair1. Despite significant advances in our understanding of lymphatic function, the precise developmental origin of lymphatic endothelial cells (LECs) has remained a point of debate for over a century2-5. It is currently widely accepted that most LECs are derived from venous endothelium4,6, although other sources have been described, including mesenchymal cells3, hemogenic endothelium7 and musculoendothelial progenitors8,9. Here we show that the initial expansion of mammalian LECs is driven primarily by the in situ differentiation of specialized angioblasts and not migration from venous endothelium. Single-cell RNA sequencing and genetic lineage tracing experiments in mouse revealed a population of Etv2+Prox1+ lymphangioblasts that arise directly from paraxial mesoderm-derived progenitors. Conditional lineage labelling and morphological analyses showed that these specialized angioblasts emerge within a tight spatiotemporal window, and give rise to LECs in numerous tissues. Analysis of early LEC proliferation and migration supported these findings, suggesting that emergence of LECs from venous endothelium is limited. Collectively, our data reconcile discrepancies between previous studies and indicate that LECs form through both de novo specification from lymphangioblasts and transdifferentiation from venous endothelium.

developmental biology↗

bioRxiv2021

SRSF3 is a key regulator of epicardial formation

The epicardium is a fundamental regulator of cardiac development and regeneration, functioning to secrete essential growth factors and to produce epicardium-derived cells (EPDCs) that contribute most coronary mural cells and cardiac fibroblasts. The molecular mechanisms controlling epicardial formation have not been fully elucidated. In this study, we found that the RNA-binding protein SRSF3 is highly expressed in the embryonic proepicardium and epicardial layer. Deletion of Srsf3 from the murine proepicardium led to proliferative arrest, which prevented proper epicardial formation. Induction of Srsf3 deletion after the proepicardial stage resulted in impaired epicardial proliferation and EPDC formation by E13.5. Single-cell RNA-sequencing showed SRSF3-depleted epicardial cells were eliminated, however, the surviving non-recombined cells became hyperproliferative and, remarkably, compensated for the early deficit, via a mechanism that involved Srsf3 up-regulation This unexpected finding attests the importance of SRSF3 in controlling epicardial proliferation, and highlights the significant confounding effect of mosaic recombination on embryonic phenotyping. Mapping the SRSF3-RNA interaction network by endogenous irCLIP identified binding to major cell cycle regulators, such as Ccnd1 and Map4k4, with both splicing and non-splicing roles. This research defines SRSF3 as a key regulator of epicardial cell proliferation.

developmental biology↗

bioRxiv2020

Tissue-resident macrophages regulate lymphatic vessel growth and patterning in the developing heart

Macrophages are components of the innate immune system with key roles in tissue inflammation and repair. It is now evident that macrophages also support organogenesis, but few studies have characterized their identity, ontogeny and function during heart development. Here, we show that resident macrophages in the subepicardial compartment of the developing heart coincide with the emergence of new lymphatics and interact closely with the nascent lymphatic capillaries. Consequently, global macrophage-deficiency led to extensive vessel disruption with mutant hearts exhibiting shortened and mis-patterned lymphatics. The origin of cardiac macrophages was linked to the yolk sac and fetal liver. Moreover, Csf1r+ and Cx3cr1+ myeloid sub-lineages were found to play essential functions in the remodeling of the lymphatic endothelium. Mechanistically, macrophage hyaluronan was found to be required for lymphatic sprouting by mediating direct macrophage-lymphatic endothelial cell interactions. Together, these findings reveal insight into the role of macrophages as indispensable mediators of lymphatic growth during the development of the mammalian cardiac vasculature.Summary statement Tissue-resident macrophages are indispensable mediators of lymphatic vessel formation during heart development and function to remodel the vascular plexus.View Full Text

developmental biology↗

bioRxiv2019

Spatiotemporal analysis reveals significant overlap of key proepicardial markers in the developing murine heart

During embryonic development, the epicardium provides a source of multipotent progenitors for cardiac lineages, including pericytes, fibroblasts and coronary smooth muscle cells. The epicardium originates from a region of splanchnopleural mesoderm known as the proepicardial organ (PEO). The potential of the epicardium to contribute to coronary endothelium has been disputed, due to conflicting lineage tracing results with different PEO Cre lines. Controversy also surrounds when epicardial cell fate becomes restricted. Using single-cell RNA-sequencing, microscopy and flow cytometry-based single molecule RNA in situ hybridisation techniques, we systematically investigated the expression of five widely used epicardial markers, Wt1, Tcf21, Tbx18, Sema3d and Scx, over the course of development. We show co-expression of all markers in the PEO and epicardial layer until E13.5, then sequential downregulation as it undergoes quiescence. Markers also decrease in invading epicardium-derived progenitors, with the exception of Tcf21, lost only in epicardium-derived mural cells. Moreover, we demonstrate that the epicardium does not significantly contribute coronary endothelium. Our findings clarify a number of prevailing discrepancies in the field and support the notion that epicardial fate is not pre-determined within the PEO.\n\nSummary statementAssessing expression of five principal (pro)epicardial markers reveals their complete overlap during early embryonic development, challenging previous dogma regarding the existence of sub-compartments and the pre-committed fate model.

developmental biology↗