Regulation of acetylated tubulin/Na+,K+-ATPase interaction by l-glutamate in non-neural cells: involvement of microtubules.

CESAR H. CASALE; GABRIELA PREVITALI; JUAN J. SERAFINO; CARLOS A. ARCE; HECTOR S. BARRA.

BIOCHIMICA AND BIOPHYSICA ACTA

ELSEVIER

Año: 2005 vol. 1721 p. 185 - 192

0006-3002

A subpopulation of membrane tubulin consisting mainly of the acetylated isotype is associated with Na+,K+-ATPase and inhibits the enzyme activity. We found recently that treatment of cultured astrocytes with l-glutamate induces dissociation of the acetylated tubulin/Na+,K+-ATPase complex, resulting in increased enzyme activity. We now report occurrence of this phenomenon in non-neural cells. As in the case of astrocytes, the effect of l-glutamate is mediated by its transporters and not by specific receptors. In COS cells, the effect of l-glutamate was reversed by its elimination from culture medium, provided that d-glucose was present. The effect of l-glutamate was not observed when Na+ was replaced by K+ in the incubation medium. The ionophore monensin, in the presence of Na+, had the same effect as lglutamate. Treatment of cells with taxol prevented the dissociating effect of l-glutamate or monensin. Nocodazole treatment of intact cells or isolated membranes dissociated the acetylated tubulin/Na+,K+-ATPase complex. The dissociating effect of nocodazol does not require Na+. These results indicate a close functional relationship among Na+,K+-ATPase, microtubules, and l-glutamate transporters, and a possible role in cell signaling pathways.