Partners in Crime

Abstract

See related article, pages 12–15 Vertebrates have evolved 2 types of blood vessels—arteries and veins—that function to supply oxygen and nutrients and remove cellular waste. To efficiently accomplish these specialized functions, arteries and veins have developed distinct morphological and molecular differences. As a result, the endothelial cells that compose arteries and veins are vastly different in their biochemical and cellular properties. During development, the nascent endothelial cells generated from hemangioblasts or angioblasts1,2 undergo tightly regulated specification and differentiation processes to adopt either the arterial or venous endothelial fate. Differentiated endothelial cells migrate and aggregate to form either arteries or veins according to their adopted fate.3 Dysregulation of these regulated events often results in devastating consequences. For instance, failure to segregate arterial and venous endothelial cells causes potentially fatal clinical conditions such as arteriovenous malformation, hereditary hemorrhagic telangiectasia, and cerebral cavernous malformation.4 Significant progress has been made in understanding how nascent endothelial cells adopt the arterial fate, resulting in identification of several key signaling molecules and their intracellular transducers involved in the specification of arterial endothelial cells.5 However, transcription factors that function …