BIOCHEMICAL-ENGINEERING OF NEURAL CELL-SURFACES BY THE SYNTHETIC N-PROPANOYL-SUBSTITUTED NEURAMINIC ACID PRECURSOR

Sialylation of glycoproteins and glycolipids plays an important role d uring development, regeneration, and pathogenesis of diseases, During times of intense plasticity within the nervous system, such as develop ment and regeneration, sialylation of neural cells is distinct from th e time of its maintenance, In this study, a synthetic precursor of neu raminic acid, N-propanoylmannosamine (N-propanoyl neuraminic acid prec ursor (P-NAP)), is applied to the culture medium of oligodendrocyte pr ogenitor cells, microglia, astrocytes, and neurons from neonatal rat b rains to alter sialylation of glycoconjugates within these cells. P-NA P is metabolized and incorporated as N-propanoyl neuraminic acid into glycoproteins of the cell membrane. P-NAP stimulates the proliferation of astrocytes and microglia but not of oligodendrocyte progenitor in vitro. However, P-NAP increases the number of oligodendrocyte progenit or cells expressing the early oligodendroglial surface marker A2B5 epi tope. In the presence of P-NAP, cerebellar neurons (but not astrocytes ) in microexplant cultures start to express the oligodendroglial proge nitor marker A2B5 epitope, which is normally undetectable on these cel ls. The controls, which were performed in the absence of any additive or in the presence of the physiological precursor of neuraminic acid, N-acetylmannosamine, did not show any increase in A2B5 expression.