What makes our furry friends furry? Well, the fur of mice actually consists of several hair types, such as guard, awl, auchene and downy zigzag hairs, but little is known about the signals that direct their development. Now, on p. 1045, Schmidt-Ullrich et al. report that the transcription factor NF-κB controls the proliferation (but not the initiation) of guard hair placodes and their growth into the mesoderm to form hair follicles. Mice with suppressed NF-κB activity or with defects in ectodysplasin A1 (Eda A1; tabby mice) or its receptor (EdaR; downless mice) have similar hair defects. By crossing NF-κB reporter mice with tabby and downlessmice, the researchers show that Eda A1/EdaR signalling activates NF-κB,which then controls guard hair placode down growth by inducing sonic hedgehog and cyclin D1 expression. Eda A1/EdaR/NF-κB signalling also controls the morphology of other hair types, and additional signals regulate NF-κB activity to control follicle growth. Thus, these findings provide new insights into the molecular mechanisms that regulate hair development.

© 2006.
2006