Controlling the stem cell niche: right time, right place, right strength

Wnt signalling through beta-catenin plays a pivotal role during embryonic pattern formation, cell fate determination and tissue homeostasis in the adult organism. In the skin, as in many other tissues, Wnt/beta-catenin signalling can control lineage determination and differentiation. However, it was not known whether Wnt/beta-catenin signalling is an immediate regulator of the stem cell niche in skin tissue. A recent publication now provides evidence that Wnt/beta-catenin signalling exerts a direct effect on the stem cell compartment by inducing quiescent stem cells to enter the cell cycle during early stages of hair follicle regeneration. In addition, the authors demonstrate that beta-catenin is required for maintenance of the stem cell pool in the tissue.((1)) The data suggest that a gradient in Wnt/beta-catenin activity levels can induce different responses within distinct cell populations reflected by activation of distinct transcriptional profiles.