title: Extracellular adenosine 5'-triphosphate elicits the expression of brain-derived neurotrophic factor exon IV mRNA in rat astrocytes.
abstract: A growing body of recent evidence indicates that ATP plays an important role in neuronal-glial communications. In this study, the authors demonstrated that extracellular ATP elicits the gene expression of brain-derived neurotrophic factor (BDNF), especially BDNF exon IV mRNA, in primary cultured rat cortical astrocytes but not in neurons. To investigate the mechanism by which ATP induces BDNF exon IV mRNA expression, the authors used immortalized astrocyte cell line RCG-12. ATP dose-dependently increased the expression of BDNF exon IV mRNA and activated BDNF promoter IV. P2Y receptor agonists (ADP and 2MeS-ADP) but not a P2X receptor agonist (alphabetaMeATP) induced the expression of BDNF exon IV mRNA. Moreover, ATP-induced BDNF exon IV mRNA upregulation was inhibited by a P2Y antagonist (MRS2179) but not by P2X antagonists (TNP-ATP and PPADS). These findings suggest the involvement of P2Y receptors in the ATP-induced transcription of the BDNF gene. Among the signal transduction inhibiters examined in this study, intracellular Ca(2+) chelator (BAPTA-AM) and Ca(2+)/calmodulin-dependent kinase (CaM kinase) inhibitors (KN-93 and W-7) attenuated ATP-induced BDNF exon IV mRNA upregulation. ATP transiently induced the phosphorylation of cAMP-responsive element-binding protein (CREB). ATP-induced CREB phosphorylation was repressed by P2Y antagonists, BAPTA-AM, and CaM kinase inhibitors. Overexpression of dominant negative CREB mutants reduced the activation of BDNF promoter IV and attenuated the upregulation of BDNF exon IV mRNA expression. These results suggest that ATP induces BDNF expression through P2Y receptor followed by the activation of CaM kinase and CREB in astrocytes. These mechanisms are likely to contribute to the enhancement of neuronal-glial networks.
authors.affiliation: Division of Molecular Genetics Research, Life Science Research Center, University of Toyama, Toyama, Japan. takasaki@cts.u-toyama.ac.jp
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takasaki
authors.forename: Satoko
authors.initials: S
authors.lastname: Takarada
authors.forename: Saori
authors.initials: S
authors.lastname: Tatsumi
authors.forename: Aiko
authors.initials: A
authors.lastname: Azegami
authors.forename: Makoto
authors.initials: M
authors.lastname: Yasuda
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fukuchi
authors.forename: Akiko
authors.initials: A
authors.lastname: Tabuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tabuchi
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tsuda
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D001253:Astrocytes / Q000502:physiology*; D019208:Brain-Derived Neurotrophic Factor / Q000096:biosynthesis* / Q000235:genetics; D002460:Cell Line; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D005091:Exons / Q000502:physiology*; D005110:Extracellular Space / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger; D000255:Adenosine Triphosphate