ATP interferes with neural cell adhesion molecule-induced neurite outgrowth.

The neural cell adhesion molecule (NCAM) is a member of the immunoglobulin superfamily and involved in the development and regeneration of the nervous system. NCAM is expressed in three major isoforms. Two of them have large intracellular domains of different lengths and are named according to their apparent molecular weight as NCAM140 or NCAM180. NCAM140 is known to promote neurite outgrowth, whereas NCAM180 stabilizes cell-cell contacts. Beside its role in neurite outgrowth, NCAM also shows ATPase activity on its extracellular domain. Here, we quantified neurite outgrowth of neuroblastoma cells, which were transfected with either NCAM140 or NCAM180 in the absence or presence of ATP. We could confirm that NCAM140 strongly promotes neurite outgrowth, whereas NCAM180 stimulates neurite outgrowth only to a minor extent. Furthermore, application of ATP reduced the NCAM-induced neurite outgrowth to background levels in a concentration-dependent and isoform-dependent manner.