miRNAs, 'stemness' and skin.

The epidermis and its appendages provide organisms with protection from the environment, keeping pathogens out and preventing the loss of essential body fluids. To perform both functions, the skin has elaborated a complex differentiation process known as cornification. The renewal capacity of the skin, which is responsible for maintaining tissue homeostasis, regenerating hair and repairing the epidermis after injury, resides in the basal proliferating compartment in which epidermal stem cells are located. These cells possess the remarkable capacity to both self-perpetuate and give rise to the differentiating cells that form mature tissues. Recent findings indicate that microRNAs have an essential role in orchestrating the formation of epidermis and skin appendages, in particular, at the interface between stemness and differentiation.