During mammalian eye development, eyelid growth and fusion protects the developing ocular surface. Now, on , Mine and colleagues report that heparin-binding EGF-like growth factor (HB-EGF)promotes the epithelial cell migration that is required for mouse eyelid closure. The researchers show that HB-EGF is expressed only at the leading edge of the migrating epithelial cell sheet during eyelid formation. By examining mouse embryos mutant or null for Hbegf, the authors found that this growth factor promotes epithelial cell migration, but not proliferation, and that its secreted form activates the EGFR-ERK signalling cascade, resulting in F-actin polymerization and epithelial sheet migration. HB-EGF also acts synergistically with TGFα to promote eyelid closure. Given that HB-EGF is involved in epithelial cell sheet migration during skin wound healing as well, it might promote the motility of other epithelial cell sheets during embryonic and adult life.
