Expression of high molecular weight astroglial extracellular proteins is altered by growth environment

Conditioned medium from primary rat cortical glia was analyzed with respect to the composition of the secreted high molecular weight protein species. Developmental characteristics of astroglia are affected by growth in the presence and absence of serum. These growth conditions had a pronounced effect on the extracellular protein profile, cellular morphology, and cell substratum adhesion. Cells cultured in defined serumless medium did not express certain proteins expressed in the presence of serum but rather synthesized proteins specifically stimulated by the defined serumless environment. A morphological change from flat amorphous to a contracted fibrous network having an increased affinity for self-self cellular adhesion rather than adhesion to the surface of the tissue culture dish was also stimulated by the defined serumless medium environment. A comparison of the extracellular proteins secreted by the rat C6 glioma and the rat PC12 cell demonstrated the cell-specific nature of the primary glial proteins.