Tenascin-C is Required for Proliferation of Astrocytes in Primary Culture

Astrocytes in primary culture can be classified morphologically into two types: fibrous astrocytes and protoplasmic astrocytes. To examine the role of tenascin-C (TN) in an in vitro astrocyte culture, primary cultures of astrocytes prepared from the brains of wild-type and of TN- deficient embryonic mice were analyzed. In primary culture of astrocytes from TN-deficient mice fibrous astrocytes did not appear and astrocytes did not become tile-shaped when they came in contact with each other. The rate of 5-bromo-2'- deoxyuridine incorporation in a cell proliferation assay was much lower for astrocytes from TN-deficient mice than for astrocytes from wild-type mice. These results suggest that TN is an essential molecule for maintaining the proliferation and proper morphology of astrocytes in primary culture. Tenascin-C (TN) is an astroglia-derived extracellular matrix glycoprotein expressed by immature astroglia and radial glia during development of the central nervous system (CNS) (1-4) and is involved in axonal growth and guidance in the developing CNS (5, 6). Although TN is thought to be an essential molecule for neuron-glia interaction during CNS development, a 1992 study by Saga et al. found that TN-deficient mice were viable and showed no abnormalities during development and continuous breeding (7). Detailed analysis of TN-deficient mice in the last ten years has revealed new functions for TN. TN- deficient mice exhibit abnormal behaviors with hyper- locomotion and poor swimming ability caused by decreased serotonin levels, dopamine transmission and tyrosine hydroxylase activity in the brain (8).