Regulation of chick early B-cell factor-1 gene expression in feather development

The chick Ebf1 (early B-cell factor-1) gene is a member of a novel family of helix loop helix transcription factors. The expression profile, regulation and significance of this gene have been extensively studied in lymphatic, nervous, adipose and muscular tissues. However, cEbfl expression, regulation and function in the feather of chick embryo have not yet been investigated. cEbfl expression was first detected throughout the mesenchymal core of some few feather placodes (D7-D7.5). After feathers became mature and grew distally (D9 and D10), the mesenchymal expression of cEbfl became confined to the caudal margin of the proximal half of all formed feather buds. Because this dynamic pattern of expression resembles that of Sonic Hedgehog (Shh) protein and bone morphogenetic protein (Bmp4) plus the crucial role of these two major signals in feather development, we hypothesized that cEbfl expression in the feather may be regulated by Shh and Bmp4. In a feather explant culture system, Shh signals are necessary to initiate and maintain cEbfl expression in the posterior half of the feather bud, while Bmp4 is crucial for the initial cEbfl expression in the anterior half of the feather bud. Inhibition of Shh, not only down-regulates cEbfl, but also changes the morphology of feather buds, which become irregular and fused. This is the first study to demonstrate that cEbfl expression in the feather bud is under the control of Shh and Bmp4 signals and that expression may play a role in the normal development of feathers. (c) 2013 Elsevier GmbH. All rights reserved.