Research Articles : New Evidence for the Involvement of the EGF Receptor Pathway in Hair Follicle Morphogenesis in uncv Mice

Hair follicle (HF) morphogenesis depends upon a delicate balance between cell proliferation and apoptosis, both of which are known to be controlled by a number of signal pathways. In this study, we utilize the uncv homozygous mouse to investigate the underlying mechanisms giving rise to the relevant phenotypes. In so doing, we have detected changes in the EGFR, Akt and MAPK signaling pathways. Our results show that the expression patterns of active Akt, MAPK and EGFR are altered with regard to localization in the outer root sheath (ORS) of the wild type mouse and in the follicular bulbs of the uncv homozygous mouse. These data suggest that EGFR signaling may play different roles in different cellular locations. Further, ectopic EGFR signaling in the follicular bulbs of the uncv homozygous mouse may lead to catagen (entrance into the apoptosis phase). Moreover, when the EGFR ligand was overexpressed in the uncv heterozygous mouse, aggravation of HF disordered development ensued. Together, these results demonstrate that EGFR participates in a functionally compartmentalized signaling network that controls follicular development homeostasis.