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Regulation of nitric oxide signaling by formation of a distal receptor-ligand complex.

ABSTRACT: The binding of nitric oxide (NO) to the heme cofactor of heme-nitric oxide/oxygen binding (H-NOX) proteins can lead to the dissociation of the heme-ligating histidine residue and yield a five-coordinate nitrosyl complex, an important step for NO-dependent signaling. In the five-coordinate nitrosyl complex, NO can reside on either the distal or proximal side of the heme, which could have a profound influence over the lifetime of the in vivo signal. To investigate this central molecular question, we characterized the Shewanella oneidensis H-NOX (So H-NOX)-NO complex biophysically under limiting and excess NO conditions. The results show that So H-NOX preferably forms a distal NO species with both limiting and excess NO. Therefore, signal strength and complex lifetime in vivo will be dictated by the dissociation rate of NO from the distal complex and the rebinding of the histidine ligand to the heme.

SUBMITTER: Guo Y

PROVIDER: S-EPMC5698159 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Regulation of nitric oxide signaling by formation of a distal receptor-ligand complex.

Guo Yirui Y Suess Daniel L M DLM Herzik Mark A MA Iavarone Anthony T AT Britt R David RD Marletta Michael A MA

Nature chemical biology 20171002 12

The binding of nitric oxide (NO) to the heme cofactor of heme-nitric oxide/oxygen binding (H-NOX) proteins can lead to the dissociation of the heme-ligating histidine residue and yield a five-coordinate nitrosyl complex, an important step for NO-dependent signaling. In the five-coordinate nitrosyl complex, NO can reside on either the distal or proximal side of the heme, which could have a profound influence over the lifetime of the in vivo signal. To investigate this central molecular question, ...[more]

PMID: 28967923

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Project description:BackgroundRegulatory functions of nitric oxide (NO*) that bypass the second messenger cGMP are incompletely understood. Here, cGMP-independent effects of NO* on gene expression were globally examined in U937 cells, a human monoblastoid line that constitutively lacks soluble guanylate cyclase. Differentiated U937 cells (>80% in G0/G1) were exposed to S-nitrosoglutathione, a NO* donor, or glutathione alone (control) for 6 h without or with dibutyryl-cAMP (Bt2cAMP), and then harvested to extract total RNA for microarray analysis. Bt2cAMP was used to block signaling attributable to NO*-induced decreases in cAMP.ResultsNO* regulated 110 transcripts that annotated disproportionately to the cell cycle and cell proliferation (47/110, 43%) and more frequently than expected contained AU-rich, post-transcriptional regulatory elements (ARE). Bt2cAMP regulated 106 genes; cell cycle gene enrichment did not reach significance. Like NO*, Bt2cAMP was associated with ARE-containing transcripts. A comparison of NO* and Bt2cAMP effects showed that NO* regulation of cell cycle genes was independent of its ability to interfere with cAMP signaling. Cell cycle genes induced by NO* annotated to G1/S (7/8) and included E2F1 and p21/Waf1/Cip1; 6 of these 7 were E2F target genes involved in G1/S transition. Repressed genes were G2/M associated (24/27); 8 of 27 were known targets of p21. E2F1 mRNA and protein were increased by NO*, as was E2F1 binding to E2F promoter elements. NO* activated p38 MAPK, stabilizing p21 mRNA (an ARE-containing transcript) and increasing p21 protein; this increased protein binding to CDE/CHR promoter sites of p21 target genes, repressing key G2/M phase genes, and increasing the proportion of cells in G2/M.ConclusionNO* coordinates a highly integrated program of cell cycle arrest that regulates a large number of genes, but does not require signaling through cGMP. In humans, antiproliferative effects of NO* may rely substantially on cGMP-independent mechanisms. Stress kinase signaling and alterations in mRNA stability appear to be major pathways by which NO* regulates the transcriptome.

Project description:At the cell surface, ?ARs and endothelin receptors can regulate nitric oxide (NO) production. ?-adrenergic receptors (?ARs) and type B endothelin receptors (ETB) are present in cardiac nuclear membranes and regulate transcription. The present study investigated the role of the NO pathway in the regulation of gene transcription by these nuclear G protein-coupled receptors. Nitric oxide production and transcription initiation were measured in nuclei isolated from the adult rat heart. The cell-permeable fluorescent dye 4,5-diaminofluorescein diacetate (DAF2 DA) was used to provide a direct assessment of nitric oxide release. Both isoproterenol and endothelin increased NO production in isolated nuclei. Furthermore, a ?3AR-selective agonist, BRL 37344, increased NO synthesis whereas the ?1AR-selective agonist xamoterol did not. Isoproterenol increased, whereas ET-1 reduced, de novo transcription. The NO synthase inhibitor l-NAME prevented isoproterenol from increasing either NO production or de novo transcription. l-NAME also blocked ET-1-induced NO-production but did not alter the suppression of transcription initiation by ET-1. Inhibition of the cGMP-dependent protein kinase (PKG) using KT5823 also blocked the ability of isoproterenol to increase transcription initiation. Furthermore, immunoblotting revealed eNOS, but not nNOS, in isolated nuclei. Finally, caged, cell-permeable isoproterenol and endothelin-1 analogs were used to selectively activate intracellular ?-adrenergic and endothelin receptors in intact adult cardiomyocytes. Intracellular release of caged ET-1 or isoproterenol analogs increased NO production in intact adult cardiomyocytes. Hence, activation of the NO synthase/guanylyl cyclase/PKG pathway is necessary for nuclear ?3ARs to increase de novo transcription. Furthermore, we have demonstrated the potential utility of caged receptor ligands in selectively modulating signaling via endogenous intracellular G protein-coupled receptors.

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Regulation of nitric oxide signaling by formation of a distal receptor-ligand complex.

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Regulation of nitric oxide signaling by formation of a distal receptor-ligand complex.

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