PMID:23940325

Citation	Couto, A, Oda, S, Nikolaev, VO, Soltesz, Z and de Bono, M (2013) In vivo genetic dissection of O2-evoked cGMP dynamics in a Caenorhabditis elegans gas sensor. Proc. Natl. Acad. Sci. U.S.A. 110:E3301-10
Abstract	cGMP signaling is widespread in the nervous system. However, it has proved difficult to visualize and genetically probe endogenously evoked cGMP dynamics in neurons in vivo. Here, we combine cGMP and Ca(2+) biosensors to image and dissect a cGMP signaling network in a Caenorhabditis elegans oxygen-sensing neuron. We show that a rise in O2 can evoke a tonic increase in cGMP that requires an atypical O2-binding soluble guanylate cyclase and that is sustained until oxygen levels fall. Increased cGMP leads to a sustained Ca(2+) response in the neuron that depends on cGMP-gated ion channels. Elevated levels of cGMP and Ca(2+) stimulate competing negative feedback loops that shape cGMP dynamics. Ca(2+)-dependent negative feedback loops, including activation of phosphodiesterase-1 (PDE-1), dampen the rise of cGMP. A different negative feedback loop, mediated by phosphodiesterase-2 (PDE-2) and stimulated by cGMP-dependent kinase (PKG), unexpectedly promotes cGMP accumulation following a rise in O2, apparently by keeping in check gating of cGMP channels and limiting activation of Ca(2+)-dependent negative feedback loops. Simultaneous imaging of Ca(2+) and cGMP suggests that cGMP levels can rise close to cGMP channels while falling elsewhere. O2-evoked cGMP and Ca(2+) responses are highly reproducible when the same neuron in an individual animal is stimulated repeatedly, suggesting that cGMP transduction has high intrinsic reliability. However, responses vary substantially across individuals, despite animals being genetically identical and similarly reared. This variability may reflect stochastic differences in expression of cGMP signaling components. Our work provides in vivo insights into the architecture of neuronal cGMP signaling.
Links	PubMed PMC3761592 Online version:10.1073/pnas.1217428110
Keywords	Animals; Biosensing Techniques; Caenorhabditis elegans/genetics; Caenorhabditis elegans/metabolism; Calcium/metabolism; Cyclic GMP/metabolism; Enzyme Activation; Gases/analysis; Oxygen/metabolism; Phosphoric Diester Hydrolases/metabolism; Signal Transduction; Synapses/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CAEEL:A8WI01	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:O18696	P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:A8WI01	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:A8WI01	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:G5EEE2	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:G5EEE2	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:GCY35	involved_in	GO:0019934: cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:GCY35	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:PDE1	enables	GO:0004115: 3',5'-cyclic-AMP phosphodiesterase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
CAEEL:PDE1	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
CAEEL:PDE1	enables	GO:0047555: 3',5'-cyclic-GMP phosphodiesterase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
CAEEL:PDE1	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:A8WI01	P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:PDE1	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:PDE1	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:EGL4	involved_in	GO:1902160: negative regulation of cyclic nucleotide-gated ion channel activity	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:A8WI01	P	occurs_in:(WBbt:0004096) has_input:(UniProtKB:A8WI01)	Seeded From UniProt	complete
CAEEL:EGL4	involved_in	GO:0051343: positive regulation of cyclic-nucleotide phosphodiesterase activity	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:O18696	P	occurs_in:(WBbt:0004096) has_input:(UniProtKB:P30645)	Seeded From UniProt	complete
CAEEL:EGL4	involved_in	GO:0010753: positive regulation of cGMP-mediated signaling	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:A8WI01	P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:EGL4	involved_in	GO:0010753: positive regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:EGL4	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:PDE2	involved_in	GO:1902160: negative regulation of cyclic nucleotide-gated ion channel activity	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:A8WI01	P	has_input:(UniProtKB:A8WI01) occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:PDE2	involved_in	GO:0010753: positive regulation of cGMP-mediated signaling	ECO:0000316: genetic interaction evidence used in manual assertion	UniProtKB:A8WI01	P		Seeded From UniProt	complete
CAEEL:PDE2	involved_in	GO:0010753: positive regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:PDE2	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:CNG	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:CNG	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:G5EEE2	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:G5EEE2	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:CNG	involved_in	GO:0070482: response to oxygen levels	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete
CAEEL:CNG	involved_in	GO:0010754: negative regulation of cGMP-mediated signaling	ECO:0000315: mutant phenotype evidence used in manual assertion		P	occurs_in:(WBbt:0004096)	Seeded From UniProt	complete

References

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