Interaction of hydrolysis-resistant analogs of cyclic GMP with the phosphodiesterase and light-sensitive channel of retinal rod outer segments.

Zimmerman, Anita L.; Yamanaka, Gregory; Eckstein, Fritz; Baylor, D. A.; Stryer, Lubert

doi:10.1073/pnas.82.24.8813

Cited by 193 publications

(113 citation statements)

References 28 publications

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“…CNG channels in patches excised from outer segments of these cones had a similar sensitivity, with a K 1/2 for cGMP of 159 ± 29 μM (n = 6). Both the terminal and outer-segment CNG channels were much more sensitive to pCPT-cGMP with a K 1/2 of activation of 10.3 ± 3.9 μM (n = 5), consistent with the higher sensitivity of other CNG channels for this analogue 9 .…”

supporting

confidence: 59%

Cyclic-nucleotide-gated channels mediate synaptic feedback by nitric oxide

Savchenko

Barnes

Krämer

1997

Nature

185

146

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Cyclic-nucleotide-gated (CNG) channels in outer segments of vertebrate photoreceptors generate electrical signals in response to changes in cyclic GMP concentration during phototransduction 1 . CNG channels also allow the influx of Ca 2+ , which is essential for photoreceptor adaptation 2 . In cone photoreceptors, cGMP triggers an increase in membrane capacitance indicative of exocytosis, suggesting that CNG channels are also involved in synaptic function 3 . Here we examine whether CNG channels reside in cone terminals and whether they regulate neurotransmitter release, specifically in response to nitric oxide (NO), a retrograde transmitter that increases cGMP synthesis and potentiates synaptic transmission in the brain [4][5][6] . Using intact retina, we show that endogenous NO modulates synapses between cones and horizontal cells. In experiments on isolated cones, we show directly that CNG channels occur in clusters and are indirectly activated by S-nitrosocysteine (SNC), an NO donor. Furthermore, both SNC and pCPTcGMP, a membrane-permeant analogue of cGMP, trigger the release of transmitter from the cone terminals. The NO-induced transmitter release is suppressed by guanylate cyclase inhibitors and prevented by direct activation of CNG channels, indicating that their activation is required for NO to elicit release. These results expand our view of CNG channel function to include the regulation of synaptic transmission and mediation of the presynaptic effects of NO.Patch-clamp experiments were performed on acutely dissociated cones from lizard retina, used because they possess large (5-10 μm diameter) presynaptic terminals (labelled T in Fig. 1a). By varying the duration of proteolytic enzyme treatment and trituration, we observed either intact cones or cones devoid of outer segments and/or presynaptic terminals. To investigate whether CNG channels are present in the terminals we applied the whole-cell patch-clamp configuration to cones containing terminals and cones lacking terminals. All the cones selected for use in these experiments were devoid of outer segments, to eliminate their contribution to the whole-cell CNG current. To ensure that the cone terminals were intact and functional, we applied depolarizing voltage pulses to assay for the presence of a voltage-gated Ca 2+ current, which has been previously characterized in cones with healthy terminals 3,7,8 .The results of these experiments are shown in Fig. 1b. All cones exhibiting a voltage-gated Ca 2+ current also exhibited an inward current when the membrane-permeant cGMP analogue pCPT-cGMP (8-para-chlorothio-cGMP) was applied (9 of 9 cells). In contrast, none of the cones without terminals exhibited either the voltage-gated Ca 2+ current or pCPT-cGMP-activated current (0 of 8 cells). To confirm that the pCPT-cGMP-activated current is specifically localized to the terminal, 'whole-terminal' recordings were obtained after isolating the terminal from the inner segment by transecting the axon with a glass probe. Isolated terminals exhibited bot...

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supporting

confidence: 59%

Cyclic-nucleotide-gated channels mediate synaptic feedback by nitric oxide

Savchenko

Barnes

Krämer

1997

Nature

185

146

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“…Compound 6 and the N7-phenyl vinyl sulfone derivative, 10, give 13 C shifts of 167.9 and 166.2 ppm respectively, while the 13 C chemical shifts for compounds with a single bond at C8-S, 7, 9, 14, and 15, are on average >20 ppm upfield: 140.9, 143.8, 140.2, and 147.8 ppm respectively. The presence of a positive charge at N7, as in compound 15, has a relatively small impact on the 13 C chemical shift at C8. Second, the uv-vis spectra of 6 and the N7-derivative, compound 8, share a characteristic two-peak shape: λ max = 288/302 nm and 288/304 nm respectively.…”

Section: Chemistrymentioning

confidence: 99%

“…Surprisingly, we observed the formation of approximately equivalent amounts of two distinct products upon reaction at pH 7.9 (Scheme 1). To further explore this unanticipated reactivity, we tested reaction of phenyl vinyl sulfone with 8-pCPT-cGMP (13), an 8-thio-cGMP derivative lacking a free thiol, and observed the formation of a single main product (Scheme 2). While vinyl sulfones are highly selective for reaction with thiols, given elevated pH (>9) and long reaction time (days) significant reaction with amines can be achieved 22 .…”

Section: Chemistrymentioning

confidence: 99%

“…The N7 vinyl sulfone derivatives, 8, 10 and 12, also adopt the thioketo form (not the charged tautomer) based on several lines of evidence. First, the 13 C chemical shift for the carbon at the 8-position is sensitive to whether C8-S is a single or a double bond. Compound 6 and the N7-phenyl vinyl sulfone derivative, 10, give 13 C shifts of 167.9 and 166.2 ppm respectively, while the 13 C chemical shifts for compounds with a single bond at C8-S, 7, 9, 14, and 15, are on average >20 ppm upfield: 140.9, 143.8, 140.2, and 147.8 ppm respectively.…”

Section: Chemistrymentioning

confidence: 99%

“…First, the 13 C chemical shift for the carbon at the 8-position is sensitive to whether C8-S is a single or a double bond. Compound 6 and the N7-phenyl vinyl sulfone derivative, 10, give 13 C shifts of 167.9 and 166.2 ppm respectively, while the 13 C chemical shifts for compounds with a single bond at C8-S, 7, 9, 14, and 15, are on average >20 ppm upfield: 140.9, 143.8, 140.2, and 147.8 ppm respectively. The presence of a positive charge at N7, as in compound 15, has a relatively small impact on the 13 C chemical shift at C8.…”

Section: Chemistrymentioning

confidence: 99%

See 2 more Smart Citations

Novel N7- and N1-Substituted cGMP Derivatives Are Potent Activators of Cyclic Nucleotide-Gated Channels

Strassmaier

Karpen

2007

J. Med. Chem.

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Cyclic nucleotide-gated (CNG) channels, key players in olfactory and visual signal transduction, generate electrical responses to odorant-and light-induced changes in cyclic nucleotide concentration. Previous work suggests that substitutions are tolerated solely at the C8 position on the purine ring of cGMP. Our studies with C8, 2′-OH, and 2-NH 2 -modified cGMP derivatives support this assertion. To gain further insight into determinants important for CNG channel binding and activation, we targeted previously unexplored positions. Modifications at N7 of 8-SH-cGMP (6) are well tolerated by olfactory and retinal rod CNG channels. Toleration of a very large substituent, a 3400 MW PEG, at either N7 or C8 argues for broad accommodation at these positions in the binding site. Modification at N1 of cGMP reduces the apparent affinity for the channel, however, when combined with 8-parachlorophenylthio-derivatization, the resulting cGMP analog is more potent than cGMP itself. These studies establish the N7 and N1 positions of cGMP as targets for modification in the design of novel CNG channel agonists.

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[7‐(Dialkylamino)coumarin‐4‐yl]methyl‐Caged Compounds as Ultrafast and Effective Long‐Wavelength Phototriggers of 8Bromo‐Substituted Cyclic Nucleotides

et al. 2003

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[7-(Dimethylamino)coumarin-4-yl]methyl (DMACM) and [7-(diethylamino)coumarin-4-yl]methyl (DEACM) esters of 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP) and 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) are described as novel caged compounds for 8-bromo-substituted cyclic nucleotides. Synthesis is accomplished by treatment of the free acids of the cyclic nucleotides with the corresponding 7(dialkylamino)-substituted 4(diazomethyl)coumarins. Irradiation of the DMACM- and DEACM-caged cyclic nucleotides with UV light stimulates the release of the cyclic nucleotides within roughly a nanosecond. The new caged compounds are resistant to hydrolysis in aqueous buffers and exhibit long-wavelength absorption properties with maxima at 400 nm, high extinction coefficients, and high quantum yields (0.15-0.31). Their favorable properties render these compounds the most efficient and rapid phototriggers of 8-bromo-substituted cyclic nucleotides known. The usefulness of the compounds for physiological studies under nondamaging light conditions was examined in HEK293 cells expressing the alpha subunit of the cyclic-nucleotide-gated (CNG) channel of cone photoreceptors (CNGA3) and of olfactory neurons (CNGA2) by using confocal laser scanning microscopy and the patch clamp technique.

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Interaction of hydrolysis-resistant analogs of cyclic GMP with the phosphodiesterase and light-sensitive channel of retinal rod outer segments.

Cited by 193 publications

References 28 publications

Cyclic-nucleotide-gated channels mediate synaptic feedback by nitric oxide

Cyclic-nucleotide-gated channels mediate synaptic feedback by nitric oxide

Novel N7- and N1-Substituted cGMP Derivatives Are Potent Activators of Cyclic Nucleotide-Gated Channels

[7‐(Dialkylamino)coumarin‐4‐yl]methyl‐Caged Compounds as Ultrafast and Effective Long‐Wavelength Phototriggers of 8Bromo‐Substituted Cyclic Nucleotides

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