Non-canonical functions of the peripheral nerve.

The peripheral nervous system (PNS) is complex and omnipresent. The PNS targets all parts of the body starting from early stages of embryonic development, and in large part, is derived from multipotent migratory neural crest stem cells. Current opinion mostly perceives the PNS as a means of communication and information exchange between the central nervous system, the rest of the body and the environment. Additionally, the PNS is largely associated with autonomic control. Being an "alternative brain" it provides local regulation of processes in organs. However, it has become evident in recent years that in addition to these main canonical functions the PNS possesses a number of other important roles in development and homeostasis of targeted tissues, for instance, in nerve-dependent regeneration. The PNS represents a niche that hosts neural crest-derived peripheral glial cells, or, in other words, neural crest-like multipotent cells throughout the entire body. These multipotent nerve-adjacent cells can be reprogrammed in vivo and play a number of roles from creating pigmentation to controlling regeneration of a limb in amphibians or skin in rodents. In the current review we outline newly emerged, non-canonical functions of the PNS and briefly describe cellular and molecular aspects of these alternative functions.