Regulation of nitric oxide/reactive oxygen species redox signaling by nNOS splicing variants

Shingo Kasamatsu, Hiroyasu Tsutsuki, Tomoaki Ida, Tomohiro Sawa, Yasuo Watanabe, Takaaki Akaike, Hideshi Ihara

Research output: Contribution to journalArticlepeer-review


We previously demonstrated different expression patterns of the neuronal nitric oxide synthase (nNOS) splicing variants, nNOS-μ and nNOS-α, in the rat brain; however, their exact functions have not been fully elucidated. In this study, we compared the enzymatic activities of nNOS-μ and nNOS-α and investigated intracellular redox signaling in nNOS-expressing PC12 cells, stimulated with a neurotoxicant, 1-methyl-4-phenylpyridinium ion (MPP+), to enhance the nNOS uncoupling reaction. Using in vitro studies, we show that nNOS-μ produced nitric oxide (NO), as did nNOS-α, in the presence of tetrahydrobiopterin (BH4), an important cofactor for the enzymatic activity. However, nNOS-μ generated more NO and less superoxide than nNOS-α in the absence of BH4. MPP + treatment induced more reactive oxygen species (ROS) production in nNOS-α-expressing PC12 cells than in those expressing nNOS-μ, which correlated with the intracellular production of 8-nitroguanosine 3′,5′-cyclic monophosphate (8-nitro-cGMP), a downstream messenger of nNOS redox signaling, and apoptosis in these cells. Furthermore, post-treatment with 8-nitro-cGMP aggravated MPP+-induced cytotoxicity via activation of the H-Ras/extracellular signal-regulated kinase signaling pathway. In conclusion, our results provide strong evidence that nNOS-μ exhibits distinctive enzymatic properties of NO/ROS production, contributing to the regulation of intracellular redox signaling, including the downstream production of 8-nitro-cGMP.

Original languageEnglish
Pages (from-to)44-52
Number of pages9
JournalNitric Oxide - Biology and Chemistry
Publication statusPublished - 2022 Mar 1
Externally publishedYes


  • 8-Nitro-cGMP
  • MPP
  • NO/ROS redox signaling
  • Neurotoxicity
  • Tetrahydrobiopterin
  • nNOS

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Clinical Biochemistry
  • Cancer Research


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