Author/Editor		Zhang, Q; Pangršič, Tina; Kreft, Marko; Kržan, Mojca; Li, Nianzhen; Sul, Jai-Yoon; Halassa, Michael; van Bockstaele, Elisabeth; Zorec, Robert; Haydon, Philip G
Title		Fusion-related release of glutamate from astrocytes
Type		članek
Source		J Biol Chem
Vol. and No.		Letnik 279, št. 13
Publication year		2004
Volume		str. 12724-33
Language		eng
Abstract		Although cell culture studies have implicated the presence of vesicle proteins in mediating the release of glutamate from astrocytes, definitive proof requires the identification of the glutamate release mechanism and the localization of this mechanism in astrocytes at synaptic locales. In cultured murine astrocytes we show an array of vesicle proteins, including SNARE proteins, and veaicular glutamate transporters that are required to fill vesicles with glutamate. Using immunocytochemistry and single-cell multiples reverse transcription PCR we demonstrate the presence of these proteins and their transcripts within astrocytes freshly isolated from the hippocampus. Moreover, immunoelectron microscopy demonstrates the presence of VGLUTl in processes of astrocytes of the hippocampus. To determine whether calcium-dependent glutamate release is mediated by exocytosis, we expressed the SNARE motif of synaptobrevin II to prevent the formation of SNARE complexes, which reduces glutamate release from astrocytes. To further determine whether vesicular exocytosis mediates calcium-dependent glutamate release from astrocytes, we performed whole cell capacitance measurements from individual astrocytes and demonstrate an increase in whole cell capacitance, coincident with glutamate release. Together, these data allow us to conclude that astrocytes in situ express vesicle proteins necessary for filling vesicles with the chemical transmitter glutamate and that astrocytes release glutamate through a vesicle- or fusion-related mechanism.
Descriptors		ASTROCYTES HIPPOCAMPUS GLUTAMATES CALCIUM EXOCYTOSIS CELLS, CULTURED IMMUNOHISTOCHEMISTRY MICROSCOPY, IMMUNOELECTRON SYNAPTIC VESICLES TRANSFECTION SYNAPTOPHYSIN POLYMERASE CHAIN REACTION PATCH-CLAMP TECHNIQUES MICE, TRANSGENIC