Expression of hes6, a new member of the Hairy/Enhancer-of-split family, in mouse development.

Genes of the Hairy/Enhancer-of-split (HES) family encode basic-Helix-Loop-Helix proteins that function as nuclear effectors of Notch signaling to regulate the transcriptional activity of several Notch target genes. Here, we report the characterization of a new member of the HES family, hes6, and describe its expression in mouse embryos ranging from 8.5 to 15.5 dpc. High levels of expression are observed in several embryonic tissues where Notch signaling is known to control cell-fate decisions, like the nervous system, muscle and thymus. In the nervous system, hes6 is initially expressed in the closing neural tube and then in the spinal cord, cranial and dorsal root ganglia, and brain neuroepithelium. During muscle development, the expression of hes6 occurs during both myoblast commitment and differentiation, being the first hes gene to reveal expression throughout embryonic myogenesis. hes6 is also expressed in epithelial cells of the embryonic respiratory, urinary and digestive systems.