Transport of sulfatides towards myelin. Effect of colchicine, monensin and calcium on their intracellular translocation.
The in vitro effect of colchicine or monensin upon sulfatide delivery from microsomes and perikarya of oligodendroglial cells and its further incorporation into myelin was studied using brain slices obtained from 18-day-old rats incubated during 20 min with [(35)S]sulfuric acid and reincubated for different times with unlabeled precursor. Labeled sulfatides were measured in a total homogenate, myelin, microsomes and perikarya of oligodendroglial cells. Neither colchicine nor monensin depressed the incorporation of [(35)S]sulfate into sulfatides of the total homogenate. However, these drugs inhibited by 50% the incorporation of labeled sulfatides into myelin. Furthermore, while the specific radioactivity present in microsomes and perikarya of oligodendroglial cells isolated from controls at 120 min decreased to about 40% of the value at 20 min, no decrease was observed in fractions obtained from slices incubated with colchicine or monensin. Similar results were obtained when the slices were incubated in "Ca(2+) free" medium. The perturbed delivery of [(35)S]sulfatides from microsomes and perikarya of oligodendroglial cells and the diminished incorporation into myelin, in the presence of monensin and colchicine, are consistent with a possible involvement of the Golgi complex and of the cytoplasmic microtubules in the transport of sulfatides towards myelin. Moreover, the transport of these galactolipids appears to require calcium.
Sato
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Programa de Investigación en Neuroquímíca (PRINEUQUI), CONICET, Departmento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires, Argentina.
Schriftman
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Larocca
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