Adenosine A2B receptor down-regulates metabotropic glutamate receptor 5 in astrocytes during postnatal development

Masayoshi Tanaka, Eiji Shigetomi, Bijay Parajuli, Hiroaki Nagatomo, Youichi Shinozaki, Yuri Hirayama, Kozo Saito, Yuto Kubota, Yosuke Danjo, Ji Hwan Lee, Sun Kwang Kim, Junichi Nabekura, Schuichi Koizumi

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Metabotropic glutamate receptor 5 (mGluR5) in astrocytes is a key molecule for controlling synapse remodeling. Although mGluR5 is abundant in neonatal astrocytes, its level is gradually down-regulated during development and is almost absent in the adult. However, in several pathological conditions, mGluR5 re-emerges in adult astrocytes and contributes to disease pathogenesis by forming uncontrolled synapses. Thus, controlling mGluR5 expression in astrocyte is critical for several diseases, but the mechanism that regulates mGluR5 expression remains unknown. Here, we show that adenosine triphosphate (ATP)/adenosine-mediated signals down-regulate mGluR5 in astrocytes. First, in situ Ca2+ imaging of astrocytes in acute cerebral slices from post-natal day (P)7-P28 mice showed that Ca2+ responses evoked by (S)-3,5-dihydroxyphenylglycine (DHPG), a mGluR5 agonist, decreased during development, whereas those evoked by ATP or its metabolite, adenosine, increased. Second, ATP and adenosine suppressed expression of the mGluR5 gene, Grm5, in cultured astrocytes. Third, the decrease in the DHPG-evoked Ca2+ responses was associated with down-regulation of Grm5. Interestingly, among several adenosine (P1) receptor and ATP (P2) receptor genes, only the adenosine A2B receptor gene, Adora2b, was up-regulated in the course of development. Indeed, we observed that down-regulation of Grm5 was suppressed in Adora2b knockout astrocytes at P14 and in situ Ca2+ imaging from Adora2b knockout mice indicated that the A2B receptor inhibits mGluR5 expression in astrocytes. Furthermore, deletion of A2B receptor increased the number of excitatory synapse in developmental stage. Taken together, the A2B receptor is critical for down-regulation of mGluR5 in astrocytes, which would contribute to terminate excess synaptogenesis during development.

Original languageEnglish
Pages (from-to)2546-2558
Number of pages13
JournalGLIA
Volume69
Issue number11
DOIs
Publication statusPublished - Nov 2021

Bibliographical note

Publisher Copyright:
© 2021 Wiley Periodicals LLC

Keywords

  • ATP
  • adenosine
  • adenosine A receptor
  • astrocytes
  • development
  • mGluR5

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