Next time you curse your hair for your bad hair day, consider thanking it instead. The hair follicle has populations of stem cells that aid in skin regeneration after injury, and a recent Development paper unravels a new role for the transcription factor Lhx2 in this process.
Populations of epithelial stem cells in hair follicles serve to rebuild the hair bulb during the normal hair cycle throughout our lives, but they also can migrate to wounded skin in order to aid in skin regeneration. This ability is quite handy—when the skin in a hairy area is injured, it heals faster and more efficiently than a wound on skin without hair. Recently, a research group illuminated the importance of the transcription factor Lhx2 in the repair of injured skin by hair follicle stem cells. Lhx2 functions in organ development, cell fate determination, and stem cell activity in some organs. In hair follicles, Lhx2 was previously known to regulate the switch between stem cell maintenance and activity. In their recent report, Mardaryev and colleagues found that Lhx2+ hair follicle cells co-express several stem cell markers. Following injury, proliferating cells in the adjacent hair follicle were positive for Lhx2 expression, as seen in the images above. Lhx2 (magenta) expression increases by days 3 and 5 following injury. Most of the dividing cells (green) also are Lhx2+. In addition, cell proliferation following injury was reduced in heterozygous Lhx2 knockout (+/–) mice. Lhx2 ensures wound re-epithelization through its regulation of Sox9 and Tcf4, while at the same time inhibiting normal hair follicle cycling via Lgr5 regulation.
Mardaryev, A., Meier, N., Poterlowicz, K., Sharov, A., Sharova, T., Ahmed, M., Rapisarda, V., Lewis, C., Fessing, M., Ruenger, T., Bhawan, J., Werner, S., Paus, R., & Botchkarev, V. (2011). Lhx2 differentially regulates Sox9, Tcf4 and Lgr5 in hair follicle stem cells to promote epidermal regeneration after injury Development, 138 (22), 4843-4852 DOI: 10.1242/dev.070284