The objectives of this proposal are to elucidate the regulation and function of cell surface glycoconjugates in the development of cells of sympatho-adrenal lineage, and to identify specific glycoconjugates as stage- and lineage-specific markers for populations of neurons, chromaffin cells of SIF cells. PC12 pheochromocytoma cells, which exhibit characteristics between chromaffin cells and neurons and can be induced to differentiate in a neuronal direction, will also be utilized as a model for sympatho-adrenal differentiation. These cells acquire further neuronal characteristics after sequential treatment with nerve growth factor (NGF) and activators of adenylate cyclase. PC12 cells express many complex fucose and sialic acid containing glycolipids. In addition, monoclonal antibodies reacting with PC12 cell glycoconjugates have been shown to define developmentally regulated nervous system antigens. In the proposed studies, the interactions of NGF, cAMP and glucocorticoids in regulating PC12 cell glycoconjugate expression will be studied. Expression of these glycoconjugates during normal development will then be established by immunocytochemistry using anti-carbohydrate antibodies. Those glycocojugates which are found to be developmentally regulated, will be studied in primary cultures of adrenal medulla and sympathetic ganglia to determine their sensitivity to regulation by NGF, cyclic AMP and glucocorticoids. Finally, the roles of specific glycoconjugates in neurite outgrowth, cell-cell, and cell-substratum interactions will be assessed. This will be done using two approaches. The expression of specific glycocojugates on subsets of primary cells will be correlated with other phenotypic characteristics, such as the ability to grow neurites, or with commitment to specific differentiation pathways. Secondly, antibodies will be added directly to PC12 and primary cell cultures in attempts to inhibit or retard the expression of those characteristics. These studies provide insight into mechanisms by which physiological messengers such as growth factors and hormones might promote or limit the expression of phenotypic traits associated with sympatho-adrenal derivatives in vivo. In addition, these studies are likely to generate a series of stage- and lineage- specific markers which may be useful for future embryological studies and for characterizing the behavior of a variety of neural and endocrine diseases.
