ALPHA-N-CATENIN EXPRESSION IN THE NORMAL AND REGENERATING CHICK SCIATIC-NERVE

The Ca2+-dependent intercellular adhesion molecule cadherin is known t o be linked to the cytoskeleton by the protein catenin, an association of which appears to be important for the cell-adhesion function of ca dherin. Catenin consists of three subtypes-alpha, beta, and gamma. In our previous study, N-cadherin was shown to be localized on the plasma lemma of normal and regenerating chick peripheral nerve. Thus, as alph a N-catenin is a subtype of alpha-catenin (which is specifically assoc iated with N-cadherin), we investigated the immunolocalization of alph a N-catenin in normal and regenerating chick sciatic nerve. In normal nerve, unmyelinated axons exhibited either intense or weak alpha N-cat enin immunoreactivity throughout the axoplasm, whereas myelinated axon s were completely immunonegative. Regenerating axons, including those derived from parent myelinated axons, showed alpha N-catenin immunorea ctivity of variable intensities in growth cones and axon shafts. Schwa nn cells were invariably devoid of immunoreactivity. Thus alpha N-cate nin is not necessarily bound to the surface plasmalemma, but is distri buted throughout the cytoplasm, suggesting that most alpha N-catenin m olecules are dissociated from N-cadherin.