ARE THE GLYPIATED ADHESION MOLECULES PREFERENTIALLY TARGETED TO THE AXONAL COMPARTMENT

The question of how the cell surface molecules may be specifically delivered to subdomains of neurons is of particular interest considering that polarized sorting to the axon could enable adhesion glycoproteins to induce fasciculation of axonal tracts, guidance to the target cell, and the establishment of synaptic contacts. It was recently proposed that GPI-anchored molecules undergo preferential delivery to the axonal surface, implicating a similar polarized sorting of glycoproteins in neurons and epithelial cells (Dotti and Simons, 1990; Dotti et al., 1991). This review focuses on the cellular and subcellular localization of several glypiated adhesion molecules (Thy-1, TAG-1, F3/F11, P-31) in the developing and adult cerebellar cortex of the mouse. We conclude that the cellular distribution of GPI-anchored adhesion molecules within neurons is very complex and depends on: 1. The neuronal cell types, for example, F3/F11 is localized in axons in granule cells but is present in all compartments of Golgi cells. 2. The molecule itself: Thy-1, TAG-1, and P-31 are present on the granule cell body, whereas at the same developmental stage, F3/F11 is restricted to the axon. 3. The differentiation state: Thy-1 delivery to the axon correlates with postsynaptic target maturation.