Hey genes in cardiovascular development.

Hey genes encode a small family of basic helix-loop-helix (bHLH) transcription factors that are related to the Drosophila hairy and Enhancer-of-split genes. They belong to the still-limited number of direct targets of the Notch signaling pathway and are thus candidate molecules to effect critical developmental decisions like lateral inhibition, boundary formation, and inductive processes in numerous tissues. Human inherited mutations such as cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukencephalopathy and Alagille syndrome, as well as several mouse models, have highlighted the role of Notch signals in cardiovascular development and maintenance. Functional analyses in both mouse and zebrafish now have shown that Hey genes appear to be the most prominent transmitters for such signals to shape the cardiovascular system during development and perhaps also in later life.