Early and extensive venous arterialization during mammalian embryogenesis
Ontology highlight
ABSTRACT: The cellular evolutions and molecular programs underlying the arteriovenous fate settling of embryonic vascular endothelial cells (ECs) are critical for understanding arteriogenesis and inspiring new approaches for regenerative biology. Using different strategies of single-cell RNA sequencing, we constructed the transcriptional landscape of early arteriovenous EC development in both mouse and human embryos, demonstrating the evolutionary conservation of principal vascular EC types and providing a series of conserved arteriovenous genes. We showed an unexpected diversity of arteriovenous characteristics in morphologically alike vascular plexus and further uncovered two transcriptomically distinct arterial EC types, whereas most of heterologous ligand-receptor pairs were shared by different arterial vasculatures. By computational predicting and further genetic lineage tracing, we revealed the widespread venous arterialization in the mid-gestational mouse embryo proper. Interestingly, we demonstrated at transcriptomic level that Notch1 was dispensable for venous arterialization but required subsequently for the arterial feature strengthening in the arterial plexus ECs. Altogether, our findings unprecedentedly detail the comprehensive single-cell mapping of early embryonic vascular ECs in vivo, decipher an asymmetric arteriovenous characteristics different than that in adults, and reveal an extensive venous-to-arterial fate conversion in the vascular plexus.
Project description:The heterogeneity of embryonic endothelial cells (ECs) especially the distinction of arteriovenous ECs remains incompletely characterized. We established a mouse single-EC transcriptomic landscape at mid-to-late gestation stage and identified 19 subclusters, including Etv2+Bnip3+ early ECs and 2 specialized ECs. Most of these subtypes were grouped by their vascular-bed types, while ECs from brain, heart and liver were grouped by their tissue origins. Unlike arterial ECs (aECs), embryonic venous (vECs) and capillary ECs (cECs) shared less markers with their adult counterparts. Notably, capillary clusters showed some venous characteristics and one of them served as an intermediate state of arteriovenous specification. Compared to the more early stage, a clear arteriovenous branch which also going through a venous plexus was identified. aECs and vECs showed distinct transcriptional modules including specific regulatory networks of transcription factors. Especially, USF1 and MECOM were verified functioning in arteriovenous differentiation through human induced pluripotent stem cells (hiPSC) differentiation models. We therefore provide a new map of endothelial heterogeneity highlighting regulation of arteriovenous specification.
Project description:The elaborate patterning of coronary arteries critically supports the high metabolic activity of the beating heart. How coronary endothelial cells coordinate hierarchical vascular remodeling and achieve arteriovenous specification remains largely unknown. Understanding the molecular and cellular cues that pattern coronary arteries is crucial to develop innovative therapeutic strategies that restore functional perfusion within the ischemic heart. Single-cell transcriptomics were used to delineate heterogeneous transcriptional states of the developing and mature coronary endothelium with a focus on sprouting endothelium and arterial cell specification. We discovered that a tip-cell-to-artery specification mechanism drives arterialization of the intramyocardial plexus and endocardial tunnels throughout life. We also identified non-overlapping intramyocardial and subepicardial tip cell populations with differential gene expression profiles and regulatory pathways, suggesting that differential sprouting programs govern the formation and specification of the venous and arterial coronary plexus.
Project description:Endothelial cells (EC) lining arteries and veins have distinct molecular and functional signatures. The (epi)genetic regulatory mechanisms underlying this heterogeneity in human EC are incompletely understood. Using genome-wide microarray screening we established a specific fingerprint of freshly isolated arterial (HUAEC) and venous EC (HUVEC) from human umbilical cord comprising 64 arterial and 12 venous genes, representing distinct functions and pathways. Among the arterial genes were 8 transcription factors, including HEY2, a downstream target of Notch signaling and the current ‘golden standard’ pathway for arterial EC specification. Short-term culture of HUAEC or HUVEC abrogated differential gene expression resulting in a default state. Erasure of arterial gene expression was at least in part due to loss of canonical Notch activity and HEY2 expression. Notably, nCounter analysis revealed that restoring HEY2 expression or Delta-like 4 (Dll4)-induced Notch signaling in cultured HUVEC or HUAEC only partially reinstated the arterial EC gene signature while combined overexpression of the 8 transcription factors restored this fingerprint much more robustly. Each transcription factor had a different impact on gene regulation, with some stimulating only few and others boosting a large proportion of arterial genes. Interestingly, although there was some overlap and cross-regulation, the transcription factors largely complemented each other in regulating the arterial EC gene profile. Thus, our study showed that Notch signaling determines only part of the arterial EC signature and identified additional novel and complementary transcriptional players in the complex regulation of human arteriovenous EC identity To identify an arteriovenous (AV) fingerprint in human endothelial cells (EC) across different vascular beds, we used microarrays on RNA from 38 EC samples corresponding to 6 cultured human arterial-EC types (hepatic artery EC or HHAEC, N=3; aorta EC or HAEC, N=2; coronary artery EC or HCAEC, N=2; iliac artery EC or HIAEC, N=2; pulmonary artery EC or HPAEC, N=3; and umbilical artery EC or HUAEC-C, N=5), 4 cultured human venous-EC types (hepatic vein EC or HHVEC, N=3; iliac vein EC or HIVEC, N=3; pulmonary vein EC or HPVEC, N=2; and umbilical vein EC or HUVEC-C, N=5), freshly isolated HUAEC (HUAEC-F, N=4) and freshly isolated HUVEC (HUVEC-F, N=4). Due to the difficulty to obtain biopsies from healthy donors, we did not have access to freshly isolated aEC or vEC matched for all cultured EC types.
Project description:The vascular system is locally specialized to accommodate widely varying blood flow and pressure and the distinct needs of individual tissues. The endothelial cells (ECs) that line the lumens of blood and lymphatic vessels play an integral role in the regional specialization of vascular structure and physiology. However, our understanding of EC diversity is limited. To explore EC specialization on a global scale, we used DNA microarrays to determine the expression profile of 53 cultured ECs. We found that ECs from different blood vessels and microvascular ECs from different tissues have distinct and characteristic gene expression profiles. Pervasive differences in gene expression patterns distinguish the ECs of large vessels from microvascular ECs. We identified groups of genes characteristic of arterial and venous endothelium. Hey2, the human homologue of the zebrafish gene gridlock, was selectively expressed in arterial ECs and induced the expression of several arterial-specific genes. Several genes critical in the establishment of left/right asymmetry were expressed preferentially in venous ECs, suggesting coordination between vascular differentiation and body plan development. Tissue-specific expression patterns in different tissue microvascular ECs suggest they are distinct differentiated cell types that play roles in the local physiology of their respective organs and tissues. A development or differentiation experiment design type assays events associated with development or differentiation or moving through a life cycle. Development applies to organism(s) acquiring a mature state, and differentiation applies to cells acquiring specialized functions. Using regression correlation
Project description:The heterogeneity of endothelial cells (ECs), lining blood vessels, across tissues remains incompletely inventoried. We constructed an atlas of >32,000 single-EC transcriptomic data from 11 tissues of the model organism Mus musculus. We propose a new classification of EC phenotypes based on transcriptome signatures and inferred putative biological features. We identified top-ranking markers for ECs from each tissue. ECs from different vascular beds (arteries, capillaries, veins, lymphatics) resembled each other across tissues, but only arterial, venous and lymphatic (not capillary) ECs shared markers, illustrating a greater heterogeneity of capillary ECs. We identified high-endothelial-venule and lacteal-like ECs in the intestines, and angiogenic ECs in healthy tissues. Metabolic transcriptomes of ECs differed amongst spleen, lung, liver, brain and testis, while being similar for kidney, heart, muscle and intestines. Within tissues, metabolic gene expression was heterogeneous amongst ECs from different vascular beds, altogether highlighting large EC heterogeneity.
Project description:Arterial and venous endothelial cells exhibit distinct molecular characteristics at early developmental stages. These lineage-specific molecular programs are instructive to the development of distinct vascular architectures and physiological conditions of arteries and veins, but their roles in angiogenesis remain unexplored. Here, we show that the caudal vein plexus in zebrafish forms by endothelial cell sprouting, migration and anastomosis, providing a venous-specific angiogenesis model. Using this model, we identified a novel compound, aplexone, which effectively suppresses venous, but not arterial, angiogenesis. Multiple lines of evidence indicate that aplexone differentially regulates arteriovenous angiogenesis by targeting the HMG-CoA reductase (HMGCR) pathway. Treatment with aplexone affects the transcription of enzymes in the HMGCR pathway and reduces cellular cholesterol levels. Injecting mevalonate, a metabolic product of HMGCR, reverses the inhibitory effect of aplexone on venous angiogenesis. In addition, aplexone treatment inhibits protein prenylation and blocking the activity of geranylgeranyl transferase induces a venous angiogenesis phenotype resembling that observed in aplexone-treated embryos. Furthermore, endothelial cells of venous origin have higher levels of proteins requiring geranylgeranylation than arterial endothelial cells and inhibiting the activity of Rac or Rho Kinase effectively reduces the migration of venous, but not arterial, endothelial cells. Taken together, our findings indicate that angiogenesis is differentially regulated by the HMGCR pathway via an arteriovenousdependent requirement for protein prenylation in zebrafish and human endothelial cells.
Project description:Mature endothelial cells (ECs) are heterogeneous, with subtypes defined by tissue origin and by position within the vascular bed. Here, we performed scRNA-seq with mouse embryonic ECs and identified 19 subclusters, including Etv2+Bnip3+ early EC progenitors. Most of these subtypes were grouped by their vascular-bed types, while ECs from brain, heart and liver were grouped by their tissue origins. Compared to arterial ECs (aECs), embryonic venous (vECs) and capillary ECs (cECs) shared less markers with their adult counterparts. cECs showed some venous characteristics. One cEC cluster with both venous and capillary features served as a branch point for aEC and vEC lineages. aECs and vECs showed distinct transcriptional regulatory networks.
Project description:The vascular system is locally specialized to accommodate widely varying blood flow and pressure and the distinct needs of individual tissues. The endothelial cells (ECs) that line the lumens of blood and lymphatic vessels play an integral role in the regional specialization of vascular structure and physiology. However, our understanding of EC diversity is limited. To explore EC specialization on a global scale, we used DNA microarrays to determine the expression profile of 53 cultured ECs. We found that ECs from different blood vessels and microvascular ECs from different tissues have distinct and characteristic gene expression profiles. Pervasive differences in gene expression patterns distinguish the ECs of large vessels from microvascular ECs. We identified groups of genes characteristic of arterial and venous endothelium. Hey2, the human homologue of the zebrafish gene gridlock, was selectively expressed in arterial ECs and induced the expression of several arterial-specific genes. Several genes critical in the establishment of left/right asymmetry were expressed preferentially in venous ECs, suggesting coordination between vascular differentiation and body plan development. Tissue-specific expression patterns in different tissue microvascular ECs suggest they are distinct differentiated cell types that play roles in the local physiology of their respective organs and tissues. A development or differentiation experiment design type assays events associated with development or differentiation or moving through a life cycle. Development applies to organism(s) acquiring a mature state, and differentiation applies to cells acquiring specialized functions. Keywords: development_or_differentiation_design
Project description:Distinct endothelial cell cycle states (early G1 vs. late G1) provide different “windows of opportunity” to enable the differential expression of genes that regulate venous and arterial specification, respectively. Endothelial cell cycle control and arterial-venous identities are disrupted in vascular malformations including arteriovenous (AV) shunts which is a hallmark of hereditary hemorrhagic telangiectasia (HHT). We show how endothelial cell late G1 arrest induced by Palbociclib modulates the expression of genes regulating arterio-venous identity and prevents AVM development induced by BMP9/10 inhibition.
Project description:Endothelial cells (EC) lining arteries and veins have distinct molecular and functional signatures. The (epi)genetic regulatory mechanisms underlying this heterogeneity in human EC are incompletely understood. Using genome-wide microarray screening we established a specific fingerprint of freshly isolated arterial (HUAEC) and venous EC (HUVEC) from human umbilical cord comprising 64 arterial and 12 venous genes, representing distinct functions and pathways. Among the arterial genes were 8 transcription factors, including HEY2, a downstream target of Notch signaling and the current ‘golden standard’ pathway for arterial EC specification. Short-term culture of HUAEC or HUVEC abrogated differential gene expression resulting in a default state. Erasure of arterial gene expression was at least in part due to loss of canonical Notch activity and HEY2 expression. Notably, nCounter analysis revealed that restoring HEY2 expression or Delta-like 4 (Dll4)-induced Notch signaling in cultured HUVEC or HUAEC only partially reinstated the arterial EC gene signature while combined overexpression of the 8 transcription factors restored this fingerprint much more robustly. Each transcription factor had a different impact on gene regulation, with some stimulating only few and others boosting a large proportion of arterial genes. Interestingly, although there was some overlap and cross-regulation, the transcription factors largely complemented each other in regulating the arterial EC gene profile. Thus, our study showed that Notch signaling determines only part of the arterial EC signature and identified additional novel and complementary transcriptional players in the complex regulation of human arteriovenous EC identity