TEMPORAL PATTERN OF PLASMINOGEN-ACTIVATOR ACTIVITY IN THE DEVELOPING CHICK CEREBELLUM

Plasminogen activators are considered to be involved in several develo pmental events. The present work aims at characterizing the developmen tal pattern of expression of plasminogen activators in the chick cereb ellum. Soluble fractions derived by ultracentrifugation from Triton X- 100 treated membrane fractions were used for determination of the enzy me activity with a radial fibrinolytic assay. By using specific inhibi tors and different anti-plasminogen activators antibodies it is shown that only one type of the enzyme, the urokinase-type plasminogen activ ator, is expressed during the cerebellum ontogeny. Our results show th e existence of a bimodal pattern of enzyme activity with two peaks tha t temporally coincide with the processes of massive neuronal migration , neurite outgrowth and synapse formation and plasticity. It is propos ed that plasminogen activator could play a role in these developmental events and that its pattern of variability is developmentally regulat ed. (C) 1997 ISDN. Published by Elsevier Science Ltd.