Ss. Scherer et al., PERIAXIN EXPRESSION IN MYELINATING SCHWANN-CELLS - MODULATION BY AXON-GLIAL INTERACTIONS AND POLARIZED LOCALIZATION DURING DEVELOPMENT, Development, 121(12), 1995, pp. 4265-4273
Periaxin is a newly described protein that is expressed exclusively by
myelinating Schwann cells. In developing nerves, periaxin is first de
tected as Schwann cells ensheathe axons, prior to the appearance of th
e proteins that characterize the myelin sheath. Periaxin is initially
concentrated in the adaxonal membrane (apposing the axon) but, during
development, as myelin sheaths mature, periaxin becomes predominately
localized at the abaxonal Schwann cell membrane (apposing the basal la
mina). In permanently axotomized adult nerves, periaxin is lost from t
he abaxonal and adaxonal membranes, becomes associated with degenerati
ng myelin sheaths and is phagocytosed by macrophages. In crushed nerve
s, in which axons regenerate and are remyelinated, periaxin is first d
etected in the adaxonal membrane as Schwann cells ensheathe regenerati
ng axons, but again prior to the appearance of other myelin proteins.
Periaxin mRNA and protein levels change in parallel with those of othe
r myelin-related genes after permanent axotomy and crush. These data d
emonstrate that periaxin is expressed by myelinating Schwann cells in
a dynamic, developmentally regulated manner. The shift in localization
of periaxin in the Schwann cell after completion of the spiralization
phase of myelination suggests that periaxin participates in membrane-
protein interactions that are required to stabilize the mature myelin
sheath.