Brain contains a functional glucose-6-phosphatase complex capable of endogenous glucose production.
Glucose is absolutely essential for the survival and function of the brain. In our current understanding, there is no endogenous glucose production in the brain, and it is totally dependent upon blood glucose. This glucose is generated between meals by the hydrolysis of glucose-6-phosphate (Glc-6-P) in the liver and the kidney. Recently, we reported a ubiquitously expressed Glc-6-P hydrolase, glucose-6-phosphatase-beta (Glc-6-Pase-beta), that can couple with the Glc-6-P transporter to hydrolyze Glc-6-P to glucose in the terminal stages of glycogenolysis and gluconeogenesis. Here we show that astrocytes, the main reservoir of brain glycogen, express both the Glc-6-Pase-beta and Glc-6-P transporter activities and that these activities can couple to form an active Glc-6-Pase complex, suggesting that astrocytes may provide an endogenous source of brain glucose.
Ghosh
Abhijit
A
Section on Cellular Differentiation, Heritable Disorders Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892-1830, USA.
Cheung
Yuk Yin
YY
Mansfield
Brian C
BC
Chou
Janice Yang
JY
D000818:Animals; D017920:Antiporters; D001253:Astrocytes / Q000201:enzymology; D001921:Brain / Q000378:metabolism*; D019556:COS Cells; D005947:Glucose / Q000096:biosynthesis*; D005952:Glucose-6-Phosphatase / Q000235:genetics / Q000502:physiology*; D051379:Mice; D009004:Monosaccharide Transport Proteins; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology; D010770:Phosphotransferases / Q000032:analysis
D017920:Antiporters; D009004:Monosaccharide Transport Proteins; C503532:Slc37a4 protein, mouse; C111261:glucose 6-phosphate(transporter); D010770:Phosphotransferases; D010744:Phosphoric Monoester Hydrolases; D005952:Glucose-6-Phosphatase; D005947:Glucose