Antagonists of the cGMP‐gated conductance of vertebrate rods block the photocurrent in scallop ciliary photoreceptors.

Gómez, Melissa; Nasi, Enrico

doi:10.1113/jphysiol.1997.sp022027

Cited by 18 publications

(12 citation statements)

References 37 publications

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“…Although 2′4′DCB has been established as an inhibitor of Na + /Ca 2+ exchange, a closely related compound, 3′4′DCB can inhibit cyclic nucleotide–gated channels (Gomez and Nasi 1997). We were concerned that the current reductions shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Electrogenic Na+/Ca2+ Exchange

Danaceau

Lucero

2000

The Journal of General Physiology

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Olfactory receptor neurons (ORNs) from the squid, Lolliguncula brevis, respond to the odors l-glutamate or dopamine with increases in internal Ca2+ concentrations ([Ca2+]i). To directly asses the effects of increasing [Ca2+]i in perforated-patched squid ORNs, we applied 10 mM caffeine to release Ca2+ from internal stores. We observed an inward current response to caffeine. Monovalent cation replacement of Na+ from the external bath solution completely and selectively inhibited the caffeine-induced response, and ruled out the possibility of a Ca2+-dependent nonselective cation current. The strict dependence on internal Ca2+ and external Na+ indicated that the inward current was due to an electrogenic Na+/Ca2+ exchanger. Block of the caffeine-induced current by an inhibitor of Na+/Ca2+ exchange (50–100 μM 2′,4′-dichlorobenzamil) and reversibility of the exchanger current, further confirmed its presence. We tested whether Na+/Ca2+ exchange contributed to odor responses by applying the aquatic odor l-glutamate in the presence and absence of 2′,4′-dichlorobenzamil. We found that electrogenic Na+/Ca2+ exchange was responsible for ∼26% of the total current associated with glutamate-induced odor responses. Although Na+/Ca2+ exchangers are known to be present in ORNs from numerous species, this is the first work to demonstrate amplifying contributions of the exchanger current to odor transduction.

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Section: Resultsmentioning

confidence: 99%

Electrogenic Na+/Ca2+ Exchange

Danaceau

Lucero

2000

The Journal of General Physiology

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“…In the G t -mediated phototransduction of vertebrate rods and cones, it has been shown that cyclic nucleotide-gated (CNG) channels are used for generating cellular responses (4,29). Similarly, in the G o -mediated phototransduction of molluscan photoreceptors, the functioning of CNG channels for generating cellular responses was inferred from pharmacological experiments (30,31). Interestingly, we also isolated a cDNA encoding a channel, which fell into the CNG subfamily including vertebrate rod, cone, and olfactory CNGs, from the box jellyfish lens eyes (Fig.…”

Section: Discussionmentioning

confidence: 99%

Jellyfish vision starts with cAMP signaling mediated by opsin-G _s cascade

Koyanagi

Takano²,

Tsukamoto³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

147

173

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Light sensing starts with phototransduction in photoreceptor cells. The phototransduction cascade has diverged in different species, such as those mediated by transducin in vertebrate rods and cones, by Gq-type G protein in insect and molluscan rhabdomeric-type visual cells and vertebrate photosensitive retinal ganglion cells, and by Go-type G protein in scallop ciliary-type visual cells. Here, we investigated the phototransduction cascade of a prebilaterian box jellyfish, the most basal animal having eyes containing lens and ciliary-type visual cells similar to vertebrate eyes, to examine the similarity at the molecular level and to obtain an implication of the origin of the vertebrate phototransduction cascade. We showed that the opsin-based pigment functions as a green-sensitive visual pigment and triggers the Gs-type G protein-mediated phototransduction cascade in the ciliary-type visual cells of the box jellyfish lens eyes. We also demonstrated the light-dependent cAMP increase in the jellyfish visual cells and HEK293S cells expressing the jellyfish opsin. The first identified prebilaterian cascade was distinct from known phototransduction cascades but exhibited significant partial similarity with those in vertebrate and molluscan ciliary-type visual cells, because all involved cyclic nucleotide signaling. These similarities imply a monophyletic origin of ciliary phototransduction cascades distributed from prebilaterian to vertebrate.M any animals sense light signals for vision and nonvisual photoreceptions. Light is captured by an opsin-based photopigment in a photoreceptor cell and leads to cellular light response through a G protein-mediated phototransduction cascade. Three kinds of phototransduction cascades have been found thus far (1). In vertebrate rods and cones, the light is absorbed by visual pigment, and the information is relayed via transducin (G t ) (2), causing the decrease of intracellular cGMP concentration to close cyclic nucleotide-gated channels (3, 4). In rhabdomeric-type visual cells of higher invertebrates, such as arthropods and molluscans, G q -type G protein passes the light information to the phosphoinositol signaling cascade (5-9), which is also found in vertebrate photosensitive retinal ganglion cells (10). In addition, we reported that the G o -type G proteinmediated phototransduction cascade (11) involving in the cGMP increase as a second messenger exists in scallop ciliary visual cells (12). Recently, the G o -mediated phototransduction cascade was also found in the ciliary photoreceptor cells of lizard parietal eyes (13). These varied phototransduction cascades are, respectively, driven by particular opsins, which belong to phylogenetically distinct opsin subfamilies (1). Because vision has evolved with phototransduction cascades and has diverged in different species, the opsin-based pigment and signaling cascade of lower invertebrates, such as prebilaterian animals, is important to understand the evolution of phototransduction, especially the origin of vertebrate vision.The...

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“…We therefore tested another possibility, namely, that the cyclic nucleotidegated anion channel (CNG channel) participates in LTM formation. We tested two kinds of CNG channel inhibitors, l-cis diltiazem (L-DIL) and 3, 4, -dechlorobenzamil (DCB); the former has been used in many animals (Nagy 1994 in Limulus; Gotow et al 1997 in mollusks) including insects (Murata et al 2006), and the latter has been used in mollusks (Gomez and Nasi 1997). Injection of L-DIL (1 mM) or DCB (1 mM) before multiple-trial conditioning completely impaired 24-h retention, while 30-min retention was normal (Fig.…”

Section: Cyclic Nucleotide-gated Anion Channel and Calmodulin Intervementioning

confidence: 99%

Critical role of nitric oxide-cGMP cascade in the formation of cAMP-dependent long-term memory

Matsumoto

Unoki²,

Aonuma³

et al. 2006

Learn. Mem.

105

140

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Cyclic AMP pathway plays an essential role in formation of long-term memory (LTM). In some species, the nitric oxide (NO)-cyclic GMP pathway has been found to act in parallel and complementary to the cAMP pathway for LTM formation. Here we describe a new role of the NO-cGMP pathway, namely, stimulation of the cAMP pathway to induce LTM. We have studied the signaling cascade underlying LTM formation by systematically coinjecting various "LTM-inducing" and "LTM-blocking" drugs in crickets. Multiple-trial olfactory conditioning led to LTM that lasted for several days, while memory induced by single-trial conditioning decayed away within several hours. Injection of inhibitors of the enzyme forming NO, cGMP, or cAMP into the hemolymph prior to multiple-trial conditioning blocked LTM, whereas injection of an NO donor, cGMP analog, or cAMP analog prior to single-trial conditioning induced LTM. Induction of LTM by injection of an NO donor or cGMP analog paired with single-trial conditioning was blocked by inhibitors of the cAMP pathway, but induction of LTM by a cAMP analog was unaffected by inhibitors of the NO-cGMP pathway. Inhibitors of cyclic nucleotide-gated channel (CNG channel) or calmodulin-blocked induction of LTM by cGMP analog paired with single-trial conditioning, but they did not affect induction of LTM by cAMP analog. Our findings suggest that the cAMP pathway is a downstream target of the NO-cGMP pathway for the formation of LTM, and that the CNG channel and calcium-calmodulin intervene between the NO-cGMP pathway and the cAMP pathway.In both vertebrates and invertebrates, nervous systems store information for short-term memory (STM) and long-term memory (LTM) by changing the strength of their synaptic connections (Kandel 2001). Studies in many species, including mollusca Aplysia, fruitflies Drosophila, and mice, suggest that STM storage is accompanied by transient changes in the strength of synaptic connections by covalent modifications of pre-existing proteins and that LTM storage, in contrast, is accompanied by enduring changes in synaptic strength that require transcription and translation of genes (Montarolo et al. 1986;DeZazzo and Tully 1995). In all of these species, formation of LTM requires an increase in intracellular cAMP and recruitment of the cAMP-dependent protein kinase (PKA) that phosphorylates the transcription factor, cAMP-responsive element-binding protein (CREB) (Bartsch et al. 1995;Yin et al. 1995;Abel et al. 1997).The roles of the cAMP pathway in the formation of LTM are often supplemented by other signaling pathways, most notably by the nitric oxide (NO)-cGMP signaling pathway (Lewin and Walters 1999;Lu et al. 1999). NO is a membrane-permeable molecule that functions in intercellular signaling in the brain (Garthwaite et al. 1988). In mice, NO contributes to late-phase longterm potentiation of synaptic transmission by stimulating soluble guanylate cyclase in target cells, and the resulting increase in cGMP concentration stimulates cGMP-dependent protein kinase (PKG), which acts in p...

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Antagonists of the cGMP‐gated conductance of vertebrate rods block the photocurrent in scallop ciliary photoreceptors.

Cited by 18 publications

References 37 publications

Electrogenic Na+/Ca2+ Exchange

Electrogenic Na+/Ca2+ Exchange

Jellyfish vision starts with cAMP signaling mediated by opsin-G _s cascade

Critical role of nitric oxide-cGMP cascade in the formation of cAMP-dependent long-term memory

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Antagonists of the cGMP‐gated conductance of vertebrate rods block the photocurrent in scallop ciliary photoreceptors.

Cited by 18 publications

References 37 publications

Electrogenic Na+/Ca2+ Exchange

Electrogenic Na+/Ca2+ Exchange

Jellyfish vision starts with cAMP signaling mediated by opsin-G s cascade

Critical role of nitric oxide-cGMP cascade in the formation of cAMP-dependent long-term memory

Contact Info

Product

Resources

About

Jellyfish vision starts with cAMP signaling mediated by opsin-G _s cascade