The Journal of Neuroscience, September 1, 1999, 19(17):7458-7467
Regulation of Mitogen-Activated Protein Kinases by Sphingolipid
Products in Oligodendrocytes
Hideki
Hida,
Sukehisa
Nagano,
Margaret
Takeda, and
Betty
Soliven
Department of Neurology and Committee on Neurobiology, The
Brain Research Institute, University of Chicago, Chicago, Illinois
60637
Sphingolipid products such as ceramide (cer), sphingosine (sph),
and sphingosine-1-phosphate (SPP) are implicated in the regulation of
cell growth and apoptosis. We have recently shown that cer, sph, and
SPP differentially modulate ionic events in cultured oligodendrocytes
(OLGs). Cer but not sph or SPP inhibits the inward rectifier
(IKir) in OLGs. To further
investigate the role of sphingolipid products in OLGs, we studied the
effect of cer, sph, and SPP on OLG survival and on the regulation of
mitogen-activated protein kinases (MAPKs). We found that cer, sph, and
SPP differentially modulate OLG survival and activation of MAPK
members. Cer causes OLG apoptosis, sph causes OLG lysis, and SPP does
not affect OLG survival. Cer induces a preferential activation of
p38
, whereas sph and SPP induce a preferential activation of
extracellular signal-regulated kinase 2 (ERK2) in OLGs. In
addition, the effect of cer on p38
activity is mimicked by the
inhibition of IKir with
Ba2+. In contrast, exposure to cer results in
increased activity of ERK2 but not of p38
in astrocytes. Cer-induced
OLG apoptosis is attenuated by a p38 inhibitor, SB203580, and by
expression of a p38
dominant negative mutant. We conclude that
p38
is the mediator in cer-induced OLG apoptosis and that
cer-induced IKir inhibition may contribute
to the sustained activation of p38
in OLGs.
Key words:
ceramide; glial cells; apoptosis; protein kinases; lipid
mediators; signal transduction
Copyright © 1999 Society for Neuroscience 0270-6474/99/19177458-10$05.00/0