Caveolin‐1 and the Organization of Glycolysis in Astrocytes: Modulation by Ammonia

Abstract

The organizational role of the membrane protein caveolin-1 (CAV-1), which is responsible for the formation of caveolae was previously examined in cultured vascular smooth muscle cells, and in cultured CAV-1 transfected lymphocytes. The distribution of the glycolytic enzymes aldolase, phosphofructokinase (PFK), pyruvate kinase (PK), and glyceraldehyde phosphate dehydrogenase (GAPDH), was previously determined using immunofluorescence confocal microscopy to validate interaction between proteins. The organizational role of CAV-1 with glycolytic enzymes PK and GAPDH, and with transporters GLUT-1 (for Glucose) and GLT-1 (for Glutamate) with CAV-1 was investigated in mouse cultured astrocytes. We found CAV-1 localizes with multiple glycolytic enzymes and also with GLUT-1 and GLT-1. We then studied the effect of 5 mM NH4Cl on CAV-1 expression in the astrocyte and found CAV-1 expression changes after exposure for 24 hour to 5 mM NH4Cl. The distribution of CAV-1 with PK was not affected after 5 mM NH4Cl incubation neither was the distribution of CAV-1 with GLUT-1 or GLT-1, but rather Metamorph linescan analysis revealed flurophore intensity was enhanced. We conclude that CAV-1 localizes with multiple glycolytic enzymes and may play a role in the formation of a glycolytic compartment in the astrocyte, similarly observed in smooth muscle cells. We propose that CAV-1 may have a role in the organization of glycolysis in astrocytes and that there may be coordinate regulation of the scaffolding protein after exposure to 5 mM NH4Cl. Support by NIH DK 60668.