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Int J Biol Sci 2007; 3(4):212-224. doi:10.7150/ijbs.3.212

Research Paper

Characterization of transcriptional regulation of neurogranin by nitric oxide and the role of neurogranin in SNP-induced cell death: implication of neurogranin in an increased neuronal susceptibility to oxidative stress

Jingang Gui#, Yan Song, Nian-Lin Reena Han, Fwu-Shan Sheu

Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
# Current address: University of Texas, Health Center at Tyler, Tyler 75708, TX, USA.

Abstract

Neurogranin (Ng), a calmodulin (CaM)-binding protein kinase C (PKC) substrate, regulates the availability of Ca2+/CaM complex and modulates the homeostasis of intracellular calcium in neurons. Previous work showed Ng oxidation by NO donor induces increase in [Ca2+]i. The current study demonstrated that the gene transcription of Ng could be up-regulated by various nitric oxide (NO) donors via a NO-soluble guanylyl cyclase (sGC)-mediated pathway. Furthermore, ectopic expression of neuronal nitric oxide synthase (nNOS) in human embryonic kidney 293 cells (HEK 293) exhibited a nNOS-concentration-dependent biphasic regulatory effect on Ng gene transcription. One of the NO donors, sodium nitroprusside (SNP), however, induced cell death of neuroblastoma Neuro-2a cells. The potency of SNP-induced cell death was shown to be higher in Neuro-2a cells expressing recombinant Ng, as compared with Neuro-2a control cells without Ng expression in cell viability and apoptosis assays. Single-cell fluorescence imaging and site-directed mutagenesis studies suggest that Ng promotes SNP-induced cell death through an amplification of calcium-mediated signaling, which requires the interaction between CaM and IQ motif of Ng. Increased neuronal susceptibility rendered by Ng in response to pathophysiological NO production is suggested to be involved in the selective vulnerability of neurons to oxidative insults in the CNS.

Keywords: neurogranin, Ca2+/CaM complex, nitric oxide, IQ motif, cell death, calcium-mediated signaling.

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How to cite this article:
Gui J, Song Y, Han NLR, Sheu FS. Characterization of transcriptional regulation of neurogranin by nitric oxide and the role of neurogranin in SNP-induced cell death: implication of neurogranin in an increased neuronal susceptibility to oxidative stress. Int J Biol Sci 2007; 3(4):212-224. doi:10.7150/ijbs.3.212. Available from http://www.ijbs.com/v03p0212.htm