RESUMEN
In this review we compare expression studies on monocyte subsets as an example to show the integrated possibilities of molecular databases and bioinformatic analysis tools. Monocytes have been recognized as cells with great plasticity and differentiation potential that play a pivotal role in revascularization processes, i.e. angiogenesis and arteriogenesis. To gain more insight in the relevant developmental programs, we compared the full-genome mRNA expression profiles of several distinct human monocyte subpopulations previously identified based on surface marker expression. These included classical and non-classical, M1 and M2 macrophages, circulating angiogenic cells (CAC), and non-monocyte-derived endothelial colony-forming cells (ECFC). Their transcriptional profiles revealed distinct and overlapping gene expression signatures and pathways reminiscent of utilization of transcription factors driving polarization into the different monocytic phenotypes. Hierarchical cluster analysis revealed that CAC are most related to M2 macrophages and unstimulated macrophages, and to a lesser extent to classical monocytes, and are quite distinct from M1 macrophages and ECFC. Analysis of the promoter region of CAC-expressed genes suggests that in particular the ETS family of transcription factors is important in CAC development. These analyses show the power of combining multiple datasets with existing databases on biological knowledge, to interpret full genome expression data.
Asunto(s)
Biología Computacional/métodos , Monocitos/metabolismo , Neovascularización Fisiológica/fisiología , Diferenciación Celular , Análisis por Conglomerados , Interpretación Estadística de Datos , Bases de Datos Factuales , Perfilación de la Expresión Génica , Regulación de la Expresión Génica/fisiología , Genoma Humano , Humanos , Macrófagos/metabolismoRESUMEN
BACKGROUND: Fibrin is a temporary matrix that not only seals a wound, but also provides a temporary matrix structure for invading cells during wound healing. Two naturally occurring fibrinogen variants, high molecular weight (HMW) and low molecular weight (LMW) fibrinogen, display different properties in supporting angiogenesis in vivo and in vitro. OBJECTIVES: This study was aimed at investigating the functional characteristics and molecular mechanisms of human microvascular endothelial cells (HMVECs) cultured on HMW and LMW fibrin matrices. METHODS AND RESULTS: HMVECs on HMW fibrin matrices showed increased proliferation and tube formation as compared with their counterparts on unfractionated and LMW fibrin. Degradation of HMW fibrin was markedly enhanced by the presence of HMVECs, that of LMW fibrin was enhanced only slightly. However, the expression levels of fibrinolysis-regulating proteins and integrins were similar. Subsequent microarray analysis revealed that the expression of 377 genes differed significantly between HMVECs cultured on HMW fibrin and those cultured on LMW fibrin. Among these genes, UNC5B, DLL4 and the DLL4-Notch downstream targets Hey1, Hey2 and Hes1 showed increased expression in HMVECs on LMW fibrin. However, pharmacologic and genetic (DLL4 small interfering RNA) inhibition of DLL4-Notch signaling blunted rather than enhanced proliferation and tube formation by HMVECs on both fibrin variants. CONCLUSIONS: Heterogeneity in naturally occurring fibrinogen strongly influences endothelial cell proliferation and tube formation, and causes alterations in gene expression, including that of DLL4-Notch. The higher fibrinolytic sensitivity of HMW fibrin in the presence of HMVECs contributes to increased tube formation. Although the expression of DLL4-Notch was altered, it did not explain the enhanced tube formation in HMW fibrin. This study provides new perspectives for biological and tissue engineering applications.
Asunto(s)
Endotelio Vascular/metabolismo , Fibrinógeno/fisiología , Regulación de la Expresión Génica/fisiología , Adhesión Celular , Proliferación Celular , Células Cultivadas , Medios de Cultivo , Endotelio Vascular/citología , Endotelio Vascular/enzimología , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Fibrinógeno/química , Fibrinólisis , Humanos , Integrinas/metabolismo , Peso Molecular , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Proteínas Proto-Oncogénicas c-akt/metabolismoRESUMEN
Atherosclerotic plaque rupture and subsequent thrombosis is the main cause of sudden coronary death. Remarkably, atherosclerosis only develops in certain predisposed areas of the vasculature. Endothelial cells in these predisposed areas experience low or oscillatory shear stress, which activates the proinflammatory and procoagulant transcription factors activator protein 1 (AP-1) and nuclear factor kappaB (NFkappaB), thus inducing a proinflammatory, procoagulant surface. In contrast, healthy endothelial cells that are exposed to prolonged high laminar shear stress, express anti-inflammatory and anticoagulant genes. The key shear stress-induced transcription factors that govern the expression of these genes are Krüppel-like factor 2 (KLF2) and nuclear factor erythroid 2-like 2 (Nrf2). Together KLF2 and Nrf2 govern approximately 70% of the shear stress-elicited gene sets. Nrf2 potently induces anti-inflammatory/antioxidant enzymes, while KLF2 induces anti-inflammatory and anticoagulant proteins, most specifically endothelial Nitric oxide synthase (eNOS) and thrombomodulin (TM). KLF2 also inhibits proinflammatory and antifibrinolytic genes through inhibition of the proinflammatory transcription factors AP-1 and NFkappaB. The widespread beneficial effects of the key transcription factors KLF2 and Nrf2 on endothelial phenotype, holds the promise that their targeted modulation might lead to a new class of cardiovascular drugs.