S. Pereyraalfonso et al., DEVELOPMENTAL PATTERN OF PLASMINOGEN-ACTIVATOR ACTIVITY IN CHICK OPTIC LOBE, International journal of developmental neuroscience, 15(6), 1997, pp. 805-812
Plasminogen activators are serine proteases which play a key role in m
orphogenesis and tissue remodelling. Two different molecular types, ti
ssue-type and urokinase-type, were identified and they were postulated
to play a role in neural development. The developing chick optic lobe
plays a central role in processing visual information. In previous st
udies we demonstrated the occurrence of high levels of plasminogen act
ivator activity in this model. The aim of the present paper is to stud
y the temporal pattern of expression of this activity and characterize
the type of plasminogen activator expressed in the developing optic l
obe. Using soluble fractions derived by ultracentrifugation from Trito
n X-100-treated membrane fractions we measured the protease activity w
ith a radial fibrinolytic assay. Employing different inhibitors of fib
rinolytic activity and a zymographic assay, we showed that the develop
ing optic lobe expresses only one type of plasminogen activator which
corresponds to an urokinase-type of 70 kDa. Our results indicate that
peaks of protease activity temporally correlate with massive neuronal
migration, neurite outgrowth and synapse formation and maturation. Thi
s suggests that a plasminogen activator could play a role in these dev
elopmental events. This consistent pattern of variability strongly sug
gests that it is developmentally regulated and, if so, it could be a r
eliable parameter to study neural plastic changes induced by modificat
ions in the environmental stimulation. (C) 1997 ISDN.