Biology subjects

Szumska, D.

Publications and source records attributed to Szumska, D..

6 recordsLinked to original sources

bioRxiv2026

Single-Cell Multimodal Profiling Reveals Maternal Diabetes-Nkx2-5 Interaction in Congenital Heart Disease in a Genetic Model Recapitulating Human Embryopathies

The etiological complexity of congenital heart disease (CHD) arises from the interaction between genetic and environmental factors. We hypothesized that environmental exposure could potentiate a genetic susceptibility, leading to an increased incidence of specific cardiac defects. To test this hypothesis, we used betaV59M+ female mice exhibiting severe hyperglycemia (>28 mmol/L) without dyslipidemia, a model we characterized that faithfully recapitulates human diabetic embryopathy. These females were crossed with males haploinsufficient for Nkx2-5, a transcription factor essential for cardiac development and implicated in human CHD. Our results show that the combination of genetic susceptibility and a hyperglycemic maternal environment (GxE) leads to a higher frequency and severity of cardiac malformations, including ventricular septal defects specifically involving the muscular septum, univentricular morphologies, and dilation with thinning of the myocardium. These structural abnormalities were associated with transcriptional changes affecting the contractile identity of the chamber myocardium. Single-nucleus multiomic profiling (snRNA-seq and snATAC-seq) of the E9.5 cardiac region revealed that the interaction between maternal diabetes and Nkx2-5 haploinsufficiency profoundly reshapes transcriptional and chromatin accessibility landscapes. These changes affect not only metabolic pathways, but also cell cycle progression in second heart field (SHF) progenitors, likely contributing to the observed structural cardiac defects. Multiomic integration further identifies a disrupted indirect Nkx2-5-Aldh1a2 regulatory axis in posterior SHF progenitors, while demonstrating that maternal diabetes selectively affects a restricted subset of Nkx2-5-dependent regulatory elements associated with cardiomyocyte maturation. Our findings establish a comprehensive single-cell multiomic resource that will facilitate the integration of human GWAS and other genomic datasets, enabling the identification and functional interpretation of disease-associated loci.

developmental biology↗

bioRxiv2026

Hypoxia differentially affects coronary vessel formation during heart development

BACKGROUNDThe coronary vessel system is a dense and diverse network of arteries, veins and capillaries formed by endothelial cells from a variety of sources. While hypoxia is a known stimulus for angiogenic sprouting generally, the exact mechanisms by which hypoxia, and resultant increased VEGFA, influences vessel growth in the heart are not clearly delineated. METHODSWe used a genetic model to mimic hypoxia through ectopic stabilisation of myocardial HIF. This enabled us to study the consequences of hypoxia without vascular depletion. Changes in coronary ECs in these hearts relative to littermate controls were assessed by single cell RNA-sequencing, and by examining the activity of enhancer:reporter transgenes active in different coronary vessel beds downstream of distinct vascular regulatory pathways. RESULTSAnalysis of hypoxia-mimic hearts found increased angiogenic gene expression alongside expanded activity of the VEGFA-MEF2-driven angiogenic regulatory pathway in a pattern that indicated increased endocardial-derived angiogenic sprouting. Conversely, regulatory pathways specifically active in the sinus venosus (SV)-derived plexus showed little variance in response to stabilized HIF, and sprouting from the SV was not expanded. Although hypoxia and increased VEGFA levels have been previously linked to increased arterial differentiation, we saw little change in initial arterial EC differentiation in the experimental hearts. However, mature coronary arterial formation was delayed. CONCLUSIONSThese observations further emphasize a direct and specific link between hypoxia and endocardial coronary vessel sprouting and suggest a role of hypoxia/VEGFA in guiding coronary arterial coalescence.

developmental biology↗

bioRxiv2026

A transcriptional code controlling fluid shear stress-induced gene expression

The formation and health of the vascular system is dependent on fluid shear stress (FSS), a hemodynamic force exerted onto endothelium by flowing blood. FSS strongly induces the endothelial expression of Kruppel-like factor 2 (KLF2), an atheroprotective TF essential for vascular development and homeostasis. Despite its early and crucial role in the cascade of cardiovascular events triggered by FSS, the transcriptional mechanisms by which FSS regulates KLF2 expression remain unclear, although they are known to involve the widely expressed MEF2 proteins. Here, we identified and characterized two FSS-dependent enhancers for KLF2 which collectively recapitulate endogenous endothelial KLF2 expression, and determined the TFs contributing to their regulation. This analysis identified an essential and precisely spaced MEF2-TBP double motif also shared by the FSS-sensitive KLF2 promoter. MEF-TBP double motifs are extremely rare across the genome but were also found within regulatory elements of three other FSS-induced KLF genes, including KLF4. Although normally part of the basal transcriptional machinery, TBP specifically bound all KLF elements at the MEF-TBP double motifs in a FSS-dependent manner. Collectively, this work demonstrates a specific and targetable requirement for combined MEF2-TBP binding during FSS-induced gene activation. Significance statementBlood flow induces a force known as fluid shear stress (FSS) which is required for vascular development and for the health of the mature arterial system. One of the first endothelial responses to FSS is the induction of Kruppel-like transcription factors (KLFs). However, the mechanisms by which FSS activates KLF gene expression are incompletely understood. In this paper, we characterized all regulatory elements involved in driving FSS-induced expression of KLF2. This identified an essential MEF2-TBP double motif that was extremely rare across the genome, yet found within regulatory elements for multiple FSS-responsive KLF genes including KLF2 and KLF4. This MEF2- and TBP-bound motif therefore enables blood flow to specifically activate the cascade of cardiovascular responses necessary for atheroprotective gene expression.

developmental biology↗

bioRxiv2025

A human arteriovenous differentiation roadmap reveals vein developmental mechanisms and vascular effects of viruses

Extracellular signals and cell-fate trajectories during vein development remain elusive, despite trailblazing insights into artery development. Here we exploit human pluripotent stem cell differentiation and mouse embryology to present a model that answers longstanding questions: vein endothelial cell (EC) differentiation unfolds in two steps driven by opposing extracellular signals. First, VEGF differentiates mesoderm into "primed" ECs, newly-defined progenitors that co-express certain arterial (SOX17) and venous (APLNR) markers. Second, primed ECs execute vein differentiation upon VEGF/ERK inhibition; however, upon VEGF activation they can instead form artery ECs. The arteriovenous plasticity of primed ECs was supported by intersectional lineage tracing. Future venous genes including NR2F2 harbor poised chromatin in primed ECs, but are only transcribed upon VEGF/ERK inhibition. SOXF transcription factors, including SOX17, confer primed ECs with vein differentiation competence. Collectively, this two-step vein differentiation model--entailing primed EC intermediates and VEGF/ERK inhibition to trigger vein differentiation--has implications for VEGF-modulating therapies.

developmental biology↗

bioRxiv2021

Maternal iron deficiency impacts the placental arterial network.

Placental vascular gene networks in mammals have been largely unexplored due to a lack of well validated molecular markers to identify them. This is required to study how they form in development, and how they are impacted by embryonic or maternal defects, which in-turn adversely affects the forming heart and vasculature. Such defects are known to be a consequence of maternal iron deficiency (ID), the most common nutrient deficiency world-wide. Here we employed marker analysis to characterise the arterial/arteriole and venous/venule endothelial cells (ECs) during normal placental development, and in the context of maternal ID. We reveal for the first time that placental ECs are unique compared with their embryonic counterparts. In the developing embryo, arterial ECs express Neuropilin1 (Nrp1), Delta-like ligand 4 (Dll4) and Notch1, while developing venous ECs express Neuropilin2 (Nrp2), Apj (Aplnr) and Ephrinb4 (Ephb4). However, in the E15.5 placenta, Nrp1 and Notch1 were restricted to arteries, but not continuing arteriole ECs. The arterial tree exclusively expressed Dll4. Nrp2 showed pan-EC expression at E15.5, while Ephb4 was not present at this stage. However, we found the placental venous vascular tree could be distinguished from the arterial tree by high versus low Endomucin (EMCN) and Apj (Aplnr) expression respectively. Using EMCN, we reveal that the placental arterial, but not venous, vascular tree is adversely impacted by maternal ID, with reduced area, total length and number of junctions of all vessels without affecting the EMCN high vessels. Defects to the embryonic cardiovascular system can therefore have a significant impact on blood flow delivery and expansion of the placental arterial tree.

developmental biology↗

bioRxiv2020

Maternal iron deficiency perturbs embryonic cardiovascular development

Congenital heart disease (CHD) is the most common type of birth defect, with a global prevalence of 0.9% of live births1. Most research in the last 30 years has focused on finding genetic causes of CHD. However, despite the association of over 100 genes with CHD, mutations in these genes only explain ~30% of cases2. Many of the remaining cases of CHD are caused by in utero exposure to environmental factors3. Here we have identified a completely new environmental teratogen causing CHD: maternal iron deficiency. In humans, iron deficiency anaemia is a major global health problem. 38% of pregnant women worldwide are anaemic4, and at least half of these are due to iron deficiency, the most prevalent micronutrient deficiency. We describe a mouse model of maternal iron deficiency anaemia that causes severe cardiovascular defects in her offspring. We show that these defects likely arise from increased retinoic acid signalling in iron deficient embryos, probably due to reduced activity of the iron-dependent retinoic acid catabolic CYP26 enzymes. The defects can be prevented by maternal iron administration early in pregnancy, and are also greatly reduced in offspring of mothers deficient in both iron and the retinoic acid precursor vitamin A. Finally, one puzzling feature of many genetic forms of CHD in humans is the considerable variation in penetrance and severity of defects. We show that maternal iron deficiency acts as a significant modifier of heart and craniofacial phenotype in a mouse model of Down syndrome. Given the high incidence of maternal iron deficiency, peri-conceptional iron monitoring and supplementation could be a viable strategy to reduce the prevalence and severity of CHD in human populations worldwide.

developmental biology↗