Regulation of acetylated tubulin/Na+,K+-ATPase interaction by L-glutamate in non-neural cells: involvement of microtubules.
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 L-glutamate. 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.
Casale
César H
CH
Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
Previtali
Gabriela
G
Serafino
Juan J
JJ
Arce
Carlos A
CA
Barra
Héctor S
HS
D000107:Acetylation; D027322:Amino Acid Transport System X-AG / Q000502:physiology; D000818:Animals; D002460:Cell Line; D018698:Glutamic Acid / Q000494:pharmacology*; D006801:Humans; D008870:Microtubules / Q000502:physiology*; D015739:Nocodazole / Q000494:pharmacology; D017239:Paclitaxel / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism*
D027322:Amino Acid Transport System X-AG; D014404:Tubulin; D018698:Glutamic Acid; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D017239:Paclitaxel; D015739:Nocodazole