Expression of genes involved in vascular development and angiogenesis in endothelial cells of adult lung

Abstract

Profiling gene expression in endothelial cells advances the understanding of normal vascular physiology and disease processes involving angiogenesis. However, endothelial cell purification has been challenging because of the difficulty of isolating cells and their low abundance. Here we examine gene expression in endothelial cells freshly isolated from lung capillaries after in vivo labeling with fluorescent cationic liposomes and purification by fluorescence-activated cell sorting (FACS). Of the 39,000 genes and expressed sequence tags evaluated on custom oligonucleotide arrays, 555 were enriched in endothelial cell fraction. These included familiar endothelial cell-associated genes such as VEGF, VEGF receptor (VEGFR)-1, VEGFR-2, angiopoietin-2, Tie1, Tie2, Edg1 receptor, VE-cadherin, claudin 5, connexin37, CD31, and CD34. Also enriched were genes in semaphorin/neuropilin (Sema3c and Nrp1), ephrin/Eph (ephrin A1, B1, B2, and EphB4), delta/notch (Hey1, Jagged 2, Notch 1, Notch 4, Numb, and Siah1b), and Wingless (Frizzled-4 and Tle1) signaling pathways involved in vascular development and angiogenesis. Expression of representative genes in alveolar capillary endothelial cells was verified by immunohistochemistry. Such expression reflects features that endothelial cells of normal lung capillaries have in common with embryonic and growing blood vessels. About half of the enriched genes, including exostosin 2, lipocalin 7, phospholipid scramblase 2, pleckstrin 2, protocadherin 1, Ryk, scube 1, serpinh1, SNF-related kinase, and several tetraspanins, had little or no previous association with endothelial cells. This approach can readily be used to profile genes expressed in blood vessels in tumors, chronic inflammation, and other sites in which endothelial cells avidly take up cationic liposomes.

Snrk-1 is involved in multiple steps of angioblast development and acts via notch signaling pathway in artery-vein specification in vertebrates

“…One EST showed both robust vascular expression and was identified in a previous screen for transcripts in lung ECs. 8 Due to its sequence similarity to other members of the sucrose nonfermenting kinase family, we followed the previous nomenclature and called it sucrose nonfermenting related kinase-1 (snrk-1). The zebrafish protein is 45% and 46% identical to human and mouse proteins, respectively ( Figure S1A).…”

Downregulation by lipopolysaccharide of Notch signaling, via nitric oxide

“…inflammation in modulating the extent of angiogenesis has been shown for many organs. A recent study has provided an approach and baseline data to address the expression of genes, by examining functionally altered endothelial cells at sites of angiogenesis in tumors, inflammation or other pathological conditions (Favre et al, 2003). This report indicates that Notch-related genes are involved in vascular development and angiogenesis (Favre et al, 2003).…”

Downregulation of EphA7 by hypermethylation in colorectal cancer

“…They also play a role in angiogenesis (Favre et al, 2003;Sullivan and Bicknell, 2003). In recent years, some of the Eph genes have been found to be overexpressed in human tumors, including neuroblastoma (Tang et al, 1999), lung carcinoma (Tang et al, 1999), gastric cancer (Kiyokawa et al, 1994;Kataoka et al, 2002), esophageal cancer (Miyazaki et al, 2003), breast cancer (Wu et al, 2004), and colorectal cancer (Stephenson et al, 2001;Liu et al, 2002Liu et al, , 2004Kataoka et al, 2004).…”