Journal of Pharmacological Sciences (Jul 2020)

Involvement of exchange protein directly activated by cAMP and tumor progression locus 2 in IL-1β production in microglial cells following activation of β-adrenergic receptors

  • Hidetoshi Tozaki-Saitoh,
  • Izumi Sasaki,
  • Tomohiro Yamashita,
  • Masako Hosoi,
  • Takahiro A. Kato,
  • Makoto Tsuda

Journal volume & issue
Vol. 143, no. 3
pp. 133 – 140

Abstract

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Endogenous noradrenaline (NA) has multiple bioactive functions and, in the central nervous system (CNS), has been implicated in modulating neuroinflammation via β-adrenergic receptors (β-ARs). Microglia, resident macrophages in the CNS, have a central role in the brain immune system and have been reported to be activated by NA. However, intracellular signaling mechanisms of the AR-mediated proinflammatory responses of microglia are not fully understood. Using a rapid and stable in vitro reporter assay system to evaluate IL-1β production in microglial BV2 cells, we found that NA and the β-AR agonist isoproterenol upregulated the IL-1β reporter activity. This effect was suppressed by β-AR antagonists. We further examined the involvement of EPAC (exchange protein directly activated by cAMP) and TPL2 (tumor progression locus 2, MAP3K8) and found that inhibitors for EPAC and TPL2 reduced AR agonist-induced IL-1β reporter activity. These inhibitors also suppressed NA-induced endogenous Il1b mRNA expression and IL-1β protein production. Our results suggest that EPAC and TPL2 are involved in β-AR-mediated IL-1β production in microglial cells, and extend our understanding of its intracellular signaling mechanism.

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