TUBULIN IN THE REGULATION OF GLUCOSE REDUCTASE AND Na+/K+-ATPase IN RATS WITH INDUCED DIABETES

RIVELLI J F; AMAIDEN M R; CAMPETELLI A N; PREVITALI G; FOSSATI F; ARCE C A; CASALE C H

Villa Carlos Paz - Córdoba

Congreso; Sociedad Argentina de investigación Bioquímica y Biología Molecular; 2008

SAIB

Part of cytosolic tubulin is associated to plasma membrane and inhibit the Na+,K+-ATPase. We demonstrated that the ATPase inhibition by tubulin in vitro is reverted by glutamate and reversibly inhibited by glucose. In erythrocytes of diabetics patients (DP), the Na+,K+-ATPase is inhibited. To determinate if tubulin is involved in the inhibition of the enzyme in these patients, ¬¬¬¬¬we studied the plasma membrane tubulin of DP?s erythrocytes. Recently we demonstrated that erythrocytes of DP have increased more than two fold the content of membrane tubulin. Similar results were found when COS or CAD cells were incubated with glucose or sorbitol. This study demonstrate that the membrane tubulin increases significantly in brain of streptozotocin induced diabetic rats or rats treated with an intraperitoneal injection of sorbitol. This increase is correlated with a decrease in Na+,K+-ATPase activity. The origin of the sorbitol in DP is due to the reduction of glucose by glucose reductase, therefore we decided to study whether the tubulin had any influence on the activity of this enzyme. Cytosolic extracts from rat brain were incubated with a tubulin preparation of the same tissue. The results show that tubulin is able to inhibit glucose reductase in vitro. These results show that tubulin could be involved in regulating glucose reductase and Na+,K+-ATPase activities of DP.