Details

Autor(en) / Beteiligte

• Hinca, Sven B.
• Salcedo, Claudia
• Wagner, Antonie
• Goldeman, Charlotte
• Sadat, Edris
• Aibar, Marco M.D.
• Maechler, Pierre
• Brodin, Birger
• Aldana, Blanca I.
• Helms, Hans C.C.

Titel

Brain endothelial cells metabolize glutamate via glutamate dehydrogenase to replenish TCA‐intermediates and produce ATP under hypoglycemic conditions

Ist Teil von

• Journal of neurochemistry, 2021-06, Vol.157 (6), p.1861-1875

Ort / Verlag

New York: Blackwell Publishing Ltd

Erscheinungsjahr

2021

Link zum Volltext

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• The endothelial cells of the blood–brain barrier participate in the regulation of glutamate concentrations in the brain interstitial fluid by taking up brain glutamate. However, endothelial glutamate metabolism has not been characterized, nor is its role in brain glutamate homeostasis and endothelial energy production known. The aim of this study was to investigate endothelial glutamate dehydrogenase (GDH) expression and glutamate metabolism and probe its functional significance. The primary brain endothelial cells were isolated from bovine and mouse brains, and human brain endothelial cells were derived from induced pluripotent stem cells. GDH expression on the protein level and GDH function were investigated in the model systems using western blotting, confocal microscopy, 13C‐glutamate metabolism, and Seahorse assay. In this study, it was shown that GDH was expressed in murine and bovine brain capillaries and in cultured primary mouse and bovine brain endothelial cells as well as in human‐induced pluripotent stem cell‐derived endothelial cells. The endothelial GDH expression was confirmed in brain capillaries from mice carrying a central nervous system‐specific GDH knockout. Endothelial cells from all tested species metabolized 13C‐glutamate to α‐ketoglutarate, which subsequently entered the tricarboxylic acid (TCA)‐cycle. Brain endothelial cells maintained mitochondrial oxygen consumption rates, when supplied with glutamate alone, whereas glutamate supplied in addition to glucose did not lead to additional oxygen consumption. In conclusion, brain endothelial cells directly take up and metabolize glutamate and utilize the resulting α‐ketoglutarate in the tricarboxylic acid cycle to ultimately yield ATP if glucose is unavailable. The aim of this study was to investigate endothelial glutamate dehydrogenase (GDH) expression and glutamate metabolism and probe its functional significance. GDH expression and appearance of glutamate derived TCA cycle intermediates were shown in brain endothelial cells from bovine, mouse and human sources. Brain endothelial cells maintained mitochondrial oxygen consumption rates, when supplied with glutamate alone, whereas glutamate supplied in addition to glucose did not lead to additional oxygen consumption. Thus, brain endothelial cells directly take up and metabolize glutamate through the GDH catalyzed reaction to yield ATP if glucose is unavailable.