Gene Expression In Human Endothelial Cells Research Articles

Single-cell RNA sequencing of human non-hematopoietic bone marrow cells reveals a unique set of inter-species conserved biomarkers for native mesenchymal stromal cells

BackgroundNative bone marrow (BM) mesenchymal stem/stromal cells (BM-MSCs) participate in generating and shaping the skeleton and BM throughout the lifespan. Moreover, BM-MSCs regulate hematopoiesis by contributing to the hematopoietic stem cell niche in providing critical cytokines, chemokines and extracellular matrix components. However, BM-MSCs contain a heterogeneous cell population that remains ill-defined. Although studies on the taxonomy of native BM-MSCs in mice have just started to emerge, the taxonomy of native human BM-MSCs remains unelucidated.MethodsBy using single-cell RNA sequencing (scRNA-seq), we aimed to define a proper taxonomy for native human BM non-hematopoietic subsets including endothelial cells (ECs) and mural cells (MCs) but with a focal point on MSCs. To this end, transcriptomic scRNA-seq data were generated from 5 distinct BM donors and were analyzed together with other transcriptomic data and with computational biology analyses at different levels to identify, characterize and classify distinct native cell subsets with relevant biomarkers.ResultsWe could ascribe novel specific biomarkers to ECs, MCs and MSCs. Unlike ECs and MCs, MSCs exhibited an adipogenic transcriptomic pattern while co-expressing genes related to hematopoiesis support and multilineage commitment potential. Furthermore, by a comparative analysis of scRNA-seq of BM cells from humans and mice, we identified core genes conserved in both species. Notably, we identified MARCKS, CXCL12, PDGFRA, and LEPR together with adipogenic factors as archetypal biomarkers of native MSCs within BM. In addition, our data suggest some complex gene nodes regulating critical biological functions of native BM-MSCs together with a preferential commitment toward an adipocyte lineage.ConclusionsOverall, our taxonomy for native BM non-hematopoietic compartment provides an explicit depiction of gene expression in human ECs, MCs and MSCs at single-cell resolution. This analysis helps enhance our understanding of the phenotype and the complexity of biological functions of native human BM-MSCs.

Antibodies against dengue virus nonstructural protein-1 induce heme oxygenase-1 via a redox-dependent pathway in human endothelial cells

Heme oxygenase (HO)-1, the inducible isoform of the first and rate-limiting enzyme of heme degradation, affords anti-inflammatory protection via its cell-type-specific effects in endothelial cells (ECs). In dengue hemorrhagic fever (DHF), which is the life-threatening form of dengue virus (DV) infection, endothelial interactions of cross-reactive antibodies against the DV nonstructural glycoprotein-1 (NS1) are associated with endothelial dysfunction. In this study, we investigated whether anti-NS1 antibodies might regulate HO-1 gene expression in human ECs. Serum from DHF patients with high anti-NS1 titers and a monoclonal anti-NS1 antibody upregulated HO-1 gene expression in human umbilical vein ECs, which was blocked by purified NS1 antigen. Immunoprecipitation studies showed that anti-NS1 antibodies specifically bound to the oxidoreductase protein disulfide isomerase (PDI) on ECs. Moreover, anti-NS1-mediated HO-1 induction was reduced by inhibition of PDI enzyme activity. Reactive oxygen species, which were generated by NADPH oxidase and in turn activated the phosphatidylinositol 3-kinase (PI3K)/Akt cascade, were involved in this upregulation of HO-1 gene expression. Finally, apoptosis of ECs caused by anti-NS1 antibodies was increased by pharmacological inhibition of HO-1 enzyme activity. In conclusion, HO-1 gene expression is upregulated by anti-NS1 antibodies via activation of a redox-dependent PDI/PI3K/Akt-mediated pathway in human ECs.

H5N1 Virus Activates Signaling Pathways in Human Endothelial Cells Resulting in a Specific Imbalanced Inflammatory Response

H5N1 influenza virus infections in humans cause a characteristic systemic inflammatory response syndrome; however, the molecular mechanisms are largely unknown. Endothelial cells (ECs) play a pivotal role in hyperdynamic septic diseases. To unravel specific signaling networks activated by H5N1 we used a genome-wide comparative systems biology approach analyzing gene expression in human ECs infected with three different human and avian influenza strains of high and low pathogenicity. Blocking of specific signaling pathways revealed that H5N1 induces an exceptionally NF-κB-dependent gene response in human endothelia. Additionally, the IFN-driven antiviral program in ECs is shown to be dependent on IFN regulatory factor 3 but significantly impaired upon H5N1 infection compared with low pathogenic influenza virus. As additional modulators of this H5N1-specific imbalanced gene response pattern, we identified HMGA1 as a novel transcription factor specifically responsible for the overwhelming proinflammatory but not antiviral response, whereas NFATC4 was found to regulate transcription of specifically H5N1-induced genes. We describe for the first time, to our knowledge, defined signaling patterns specifically activated by H5N1, which, in contrast to low pathogenic influenza viruses, are responsible for an imbalance of an overwhelming proinflammatory and impaired antiviral gene program.

Activation of AMPK stimulates heme oxygenase-1 gene expression and human endothelial cell survival

The present study determined whether AMP-activated protein kinase (AMPK) regulates heme oxygenase (HO)-1 gene expression in endothelial cells (ECs) and if HO-1 contributes to the biological actions of this kinase. Treatment of human ECs with the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) stimulated a concentration- and time-dependent increase in HO-1 protein and mRNA expression that was associated with a prominent increase in nuclear factor-erythroid 2-related factor 2 (Nrf2) protein. Induction of HO-1 was also observed in rat carotid arteries after the in vivo application of AICAR. Induction of HO-1 by AICAR was blocked by the AMPK inhibitor compound C, the adenosine kinase inhibitor 5'-iodotubercidin, and by silencing AMPK-α(1/2) and was mimicked by the AMPK activator A-769662 and by infecting ECs with an adenovirus expressing constitutively active AMPK-α(1). AICAR also induced a significant rise in HO-1 promoter activity that was abolished by mutating the antioxidant responsive elements of the HO-1 promoter or by the overexpression of dominant negative Nrf2. Finally, activation of AMPK inhibited cytokine-mediated EC death, and this was prevented by the HO inhibitor tin protoporphyrin-IX or by silencing HO-1 expression. In conclusion, AMPK stimulates HO-1 gene expression in human ECs via the Nrf2/antioxidant responsive element signaling pathway. The induction of HO-1 mediates the antiapoptotic effect of AMPK, and this may provide an important adaptive response to preserve EC viability during periods of metabolic stress.

Transcriptional profiling of human cavernosal endothelial cells reveals distinctive cell adhesion phenotype and role for claudin 11 in vascular barrier function

To determine specific molecular features of endothelial cells (ECs) relevant to the physiological process of penile erection we compared gene expression of human EC derived from corpus cavernosum of men with and without erectile dysfunction (HCCEC) to coronary artery (HCAEC) and umbilical vein (HUVEC) using Affymetrix GeneChip microarrays and GeneSifter software. Genes differentially expressed across samples were partitioned around medoids to identify genes with highest expression in HCCEC. A total of 190 genes/transcripts were highly expressed only in HCCEC. Gene Ontology classification indicated cavernosal enrichment in genes related to cell adhesion, extracellular matrix, pattern specification and organogenesis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed high expression of genes relating to ECM-receptor interaction, focal adhesions, and cytokine-cytokine receptor interaction. Real-time PCR confirmed expression differences in cadherins 2 and 11, claudin 11 (CLDN11), desmoplakin, and versican. CLDN11, a component of tight junctions not previously described in ECs, was highly expressed only in HCCEC and its knockdown by siRNA significantly reduced transendothelial electrical resistance in HCCEC. Overall, cavernosal ECs exhibited a transcriptional profile encoding matrix and adhesion proteins that regulate structural and functional characteristics of blood vessels. Contribution of the tight junction protein CLDN11 to barrier function in endothelial cells is novel and may reflect hemodynamic requirements of the corpus cavernosum.

Cultured endothelial cells display endogenous activation of the canonical Wnt signaling pathway and express multiple ligands, receptors, and secreted modulators of Wnt signaling

A growing body of evidence implicates Wnt signaling in the control of angiogenesis. To better understand the role of the Wnt/beta-catenin pathway in endothelial cells (EC), we examined endogenous signaling activity and signaling component expression in vascular cells. We observed stabilization of cytosolic beta-catenin and activation of a T-cell factor (TCF) -luciferase promoter, hallmarks of canonical Wnt signaling activity, in cultured EC. This activity was increased in subconfluent EC, which are known to display characteristics of angiogenic EC, compared with confluent EC, which have a more differentiated phenotype. Endogenous TCF activity was inhibited by transfection with a secreted inhibitor of canonical Wnt signaling. A systematic analysis of Wnt, Fzd, SFRP, and Dkk gene expression in human EC (cultured and freshly isolated), smooth muscle cells (cultured), and aorta demonstrated that numerous Wnt signaling components are expressed by vascular cells. We conclude that Wnt signaling components are expressed and active in cultured EC.

The use of suppression subtractive hybridization for the study of SDF-1α induced gene-expression in human endothelial cells

Stromal cell-derived factor-1 (SDF-1), the only ligand of the CXCR4 receptor, is mainly known as a chemotactic factor for hematopoietic progenitor cells. However, studies of knock-out mice have shown malformation of different organ-systems suggesting that SDF-1 may have a role in angiogenesis and cardiac and cerebral development. However, the underlying mechanisms of its action are largely unknown. Therefore, we performed suppression subtractive hybridization (SSH) in order to identify genes that are differentially expressed after stimulation of human arterial endothelial cells (HUAEC) with SDF-1. Using SSH we found ten genes, with varied functions, whose mRNA expression is induced by SDF-1α in HUAEC. We show that SSH is a reliable method for identifying differentially expressed genes and that SDF-1α may have more functions than previously reported.