MODULATION OF THROMBOSPONDIN EXPRESSION DURING DIFFERENTIATION OF EMBRYONAL CARCINOMA-CELLS

The thrombospondins (TSPs) are a family of extracellular glycoproteins that display distinct patterns of temporal and spatial expression dur ing development. In this study, we investigated the expression of two of the TSPs-TPS1 and TSP2-during the course of differentiation of embr yonal carcinoma cells in vitro. We report that both TSP1 and TSP2 mRNA and protein synthesis are induced during the differentiation of P19EC cells into neurons, glial cells, and fibroblasts. Immunofluorescence studies indicate that TSP1 displays a fibrillar pattern of staining, c haracteristic of an extracellular matrix protein, in differentiated P1 9EC cells. In contrast, TSP2 is cell-associated and is present on diff erentiated P19EC cells and on primary neurons and glial cells obtained from a 17-day embyronic mouse cerebral cortex. Interestingly, althoug h both TSP1 and TSP2 are more prevalent in areas of differentiated cel ls, they display distinct patterns of deposition. These observations s uggest that TSP1 and TSP2 may function differently during neurogenesis . The response of TSP1 and TSP2 to differentiation of P1 9EC cells ind icates that this cell system will serve as a valuable model for the st udy of TSP expression and function during neurogenesis. (C) 1994 Wiley -Liss, Inc.