Lrig1 Expression Defines a Distinct Multipotent Stem Cell Population in Mammalian Epidermis

The study identified Lrig1 as a marker for a distinct multipotent stem cell population in the mammalian epidermis, particularly in the hair follicle junctional zone. Lrig1-expressing cells were capable of giving rise to all adult epidermal lineages, although they were primarily bipotent under normal conditions, contributing to the sebaceous gland and interfollicular epidermis. Loss of Lrig1 led to increased stem cell proliferation and epidermal hyperproliferation, and it was found to regulate stem cell quiescence. The study also discovered that Lrig1 and cMyc formed an autoregulatory feedback loop, with Lrig1 negatively regulating Myc expression. This research provided insights into the regulation of epidermal stem cell proliferation and differentiation, suggesting that Lrig1-positive cells represented a previously unidentified reservoir of adult mouse interfollicular epidermal stem cells.