Effects of apotransferrin upon different components of the cytoskeleton in primary oligodendroglial cell cultures

Abstract

Apotransferrin (aTf) produces and acceleration of oligodendroglial cell (OLGc) differentiation (Marta 2000).This effect seems to be directly mediated by an action of aTf upon the OLGc cytoskeleton (CSK) (Escobar 2000).When tissue slice cultures, obtained from 3 to 4‐day‐old‐rats, were treated with 125I‐aTf, the presence of the radioactive aTf was bound to elements of the CSK isolated from these preparations. Using the same experimental design and after the isolation of microtubules (MT) and associated proteins, the radioactive aTf was associated with MT. In primary OLGc cultures,the expression of different components of the myelin CSK such as actin, tubulin and microtubule associated proteins as well as the ‘stable tubulin only peptide’ (STOP) were increased by treatment with aTf. This increase was followed by an increase in the expression of myelin basic protein and 2′3′cyclic nucleotide phosphohydrolase. In the same cultures and using immunocytochemical techniques,we analyzed the localization of endogenous (rat) and of exogenously added (human) aTf, as well as tubulin and actin, after treating the cultures with different drugs affecting the CSK (colchicine,cytochalasine and taxol). The patterns of association of these components observed in control cultures changed significantly in the cultures treated with drugs affecting the CSK. aTf seems to be acting in close association with the CSK of the OLGc, increasing the expression of tubulin and STOP in order to stabilize the MT. It produces an increase in the number of OLGc processes resulting as a consequence, in a more differentiated cell.