Epidermal lineage commitment occurs when multipotent stem cells are specified to three lineages: the epidermis, the hair follicle, and the sebaceous gland (SG). How and when a lineage becomes specified remains unknown. Here, we report the existence of a population of unipotent progenitor cells that reside in the SG and express the transcriptional repressor Blimp1. Using cell-culture studies and...

Merkel cells (MCs) are located in the touch-sensitive area of the epidermis and mediate mechanotransduction in the skin. Whether MCs originate from embryonic epidermal or neural crest progenitors has been a matter of intense controversy since their discovery >130 yr ago. In addition, how MCs are maintained during adulthood is currently unknown. In this study, using lineage-tracing experiments, ...

The skin epidermis contains different appendages such as the hair follicle and the sebaceous glands. Recent studies demonstrated that several types of stem cells (SCs) exist in different niches within the epidermis and maintain discrete epidermal compartments, but the exact contribution of each SC populations under physiological conditions is still unclear. In addition, the precise mechanisms c...

Normal human epidermis, long since dismissed as merely a protective covering for the body, is now recognized as a complex immunological unit . This concept is based on the demonstration that Langerhans cells (LCs)t are potent APCs for a variety of T cell (TC) responses and that keratinocytes (KC), at least upon stimulation, can secrete a plethora of immunomodulating cytokines (reviewed in refer...

Epithelial stem cells in adult mammalian skin are known to maintain epidermal, follicular and sebaceous lineages during homeostasis. Recently, Merkel cell mechanoreceptors were identified as a fourth lineage derived from the proliferative layer of murine skin epithelium; however, the location of the stem or progenitor population for Merkel cells remains unknown. Here, we have identified a previ...

Polycomb group proteins control a hierarchy of gene expression during the differentiation of stem cells. In this issue, Ezhkova et al. (2009) show that repression mediated by Polycomb proteins controls the timing of differentiation of precursor cells of the epidermal lineage.

Lineage Analysis of Epidermal Stem Cells Maria P. Alcolea and Philip H. Jones and Collective Regenerative Behavior Macroenvironmental Regulation of Hair Cycling Maksim V. Plikus and Cheng-Ming Chuong Cutaneous Notch Signaling in Health and Disease Craig Nowell and Freddy Radtke Metagenomics and Molecular Microbiology Microbial Ecology of the Skin in the Era of Geoffrey D. Hannigan and Elizabeth...

Epithelialization of chronic cutaneous wound is troublesome and may require use of skin/cell substitutes. Adipose-derived mesenchymal stem cells (ADMSCs) have immense potential as autologous cell source for treating wounds; they can cross the germ layer boundary of differentiation and regenerate skin. When multipotent adult stem cells are considered for skin regeneration, lineage committed kera...

Epigenetic regulators are essential for cell lineage choices during development. In this issue, Mardaryev et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201506065) show that Polycomb subunit Cbx4 acts downstream of transcriptional regulator p63 to maintain epidermal progenitor identity and proliferation in the developing epidermis via Polycomb-dependent and -independent SUMO E3 ligas...