The close homologue of the neural adhesion molecule L1 (CHL1): patterns ofexpression and promotion of neurite outgrowth by heterophilic interactions

The close homologue of L1 (CHL1), a member of the L1 family of neural adhes ion molecules, is first expressed at times of neurite outgrowth during brai n development, and is detectable in subpopulations of neurons, astrocytes, oligodendrocyte precursors and Schwann cells of the mouse and rat. Aggregat ion assays with CHL1-transfected cells show that CHL1 does not promote hemo philic adhesion or does it mediate heterophilic adhesion with L1. CHL1 prom otes neurite outgrowth by hippocampal and small cerebellar neurons in subst rate-bound and soluble form. The observation that CHL1 and L1 show overlapp ing, but also distinct patterns of synthesis in neurons and glia, suggests differential effects of L1-like molecules on neurite outgrowth.