Activation of glycogen synthase kinase 3 beta (GSK-3 beta) by platelet activating factor mediates migration and cell death in cerebellar granule neurons
N. Tong et al., Activation of glycogen synthase kinase 3 beta (GSK-3 beta) by platelet activating factor mediates migration and cell death in cerebellar granule neurons, EUR J NEURO, 13(10), 2001, pp. 1913-1922
Children with vertically acquired HIV-1 can present with a rapidly progress
ive encephalopathy and neuronal apoptosis in the first 12-18 months of life
. Furthermore, abnormal prenatal platelet activating factor (PAF) signallin
g may result in lissencephaly, a disorder of neuronal migration. PAF, produ
ced from human immunodeficiency virus type 1 (HIV-1) -infected brain-reside
nt macrophages, induces neuronal apoptosis in cultured cerebellar granule n
eurons (CGNs) in part by activating glycogen synthase kinase 3 beta (GSK-3
beta). However, PAF can also inhibit migration of CGNs that are dispersed a
nd allowed to reaggregate. Therefore, we investigated the biological effect
s following activation of GSK-3 beta by PAF, and whether these effects were
dependent on the culture conditions of the CGNs. We show here that activat
ion of neuronal GSK-3 beta by PAF is receptor-specific, with similar kineti
cs of activation in both monolayer cultures of CGNs that have ceased to mig
rate and reaggregate cultures of CGNs that are actively migrating. However,
PAF receptor activation in reaggregated CGNs inhibits neuronal migration a
nd induces approximately half the level of neuronal apoptosis compared with
PAF-treated CGN cultures that have ceased to migrate. PAF-mediated inhibit
ion of neuronal migration in reaggregated CGNs or induction of apoptosis in
CGNs that have ceased to migrate can be reversed by either PAF receptor an
tagonists, or the GSK-3 beta inhibitors lithium or valproic acid, in a dose
-dependent manner. Abnormal PAF signalling that results in GSK-3 beta overa
ctivation may represent a common mechanism for pathological defects in neur
onal migration in the prenatal period and neuronal apoptosis in the postnat
al period.