Adaptation of Mammalian Photoreceptors to Background Light: Putative Role for Direct Modulation of Phosphodiesterase

Fain, Gordon

doi:10.1007/s12035-011-8205-1

Cited by 23 publications

(22 citation statements)

References 54 publications

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“…But when the duration of dark adaptation is beyond a few hours, rhodopsin regeneration is insufficient to account for the further sensitivity increase [37]. Other current exist mechanism also cannot fully explain the delicate changes in sensitivity during adaptation, suggesting there may be unknown mechanism [38]–[40]. Our results suggest a possible scenario, namely that dark adaptation steadily increases phosphorylation of RGS9-1, which dissociates RGS9-1/Gb5L from R9AP and redistributes it to the inner segments.…”

Section: Discussionmentioning

confidence: 73%

Light-Induced Translocation of RGS9-1 and Gβ5L in Mouse Rod Photoreceptors

et al. 2013

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The transducin GTPase-accelerating protein complex, which determines the photoresponse duration of photoreceptors, is composed of RGS9-1, Gβ5L and R9AP. Here we report that RGS9-1 and Gβ5L change their distribution in rods during light/dark adaptation. Upon prolonged dark adaptation, RGS9-1 and Gβ5L are primarily located in rod inner segments. But very dim-light exposure quickly translocates them to the outer segments. In contrast, their anchor protein R9AP remains in the outer segment at all times. In the dark, Gβ5L's interaction with R9AP decreases significantly and RGS9-1 is phosphorylated at S475 to a significant degree. Dim light exposure leads to quick de-phosphorylation of RGS9-1. Furthermore, after prolonged dark adaptation, RGS9-1 and transducin Gα are located in different cellular compartments. These results suggest a previously unappreciated mechanism by which prolonged dark adaptation leads to increased light sensitivity in rods by dissociating RGS9-1 from R9AP and redistributing it to rod inner segments.

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Section: Discussionmentioning

confidence: 73%

Light-Induced Translocation of RGS9-1 and Gβ5L in Mouse Rod Photoreceptors

et al. 2013

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“…Thus, adaptation occurs although melanopsin depletion is negligible, implicating the existence of Ca 2+ -independent, active adaptation. No obvious Ca 2+ -independent, active adaptation has been reported in rods and cones (20,37) (especially so in situ) or in invertebrate rhabdomeric photoreceptors (44,45).…”

Section: Resultsmentioning

confidence: 99%

Adaptation to steady light by intrinsically photosensitive retinal ganglion cells

Yau

2013

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

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Intrinsically photosensitive retinal ganglion cells (ipRGCs) are recently discovered photoreceptors in the mammalian eye. These photoreceptors mediate primarily nonimage visual functions, such as pupillary light reflex and circadian photoentrainment, which are generally expected to respond to the absolute light intensity. The classical rod and cone photoreceptors, on the other hand, mediate image vision by signaling contrast, accomplished by adaptation to light. Experiments by others have indicated that the ipRGCs do, in fact, light-adapt. We found the same but, in addition, have now quantified this light adaptation for the M1 ipRGC subtype. Interestingly, in incremental-flash-on-background experiments, the ipRGC's receptor current showed a flash sensitivity that adapted in background light according to the Weber-Fechner relation, well known to describe the adaptation behavior of rods and cones. Part of this light adaptation by ipRGCs appeared to be triggered by a Ca 2+ influx, in that the flash response elicited in the absence of extracellular Ca 2+ showed a normal rising phase but a slower decay phase, resulting in longer time to peak and higher sensitivity. There is, additionally, a prominent Ca 2+ -independent component of light adaptation not typically seen in rods and cones or in invertebrate rhabdomeric photoreceptors.

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“…In one model, heat stress triggers a cGMP signal, which activates CNGC16, similar to what happens in the animal olfactory response pathway (Leinders-Zufall et al, 1995). However, as discussed above, an increase in cGMP under stress conditions might alternatively reflect a new steady-state basal level, similar to what happens in animal vision when rod cells adapt to darkness (Fain, 2011).…”

Section: A General Model For a Cnmp-triggered Heat Stress Responsementioning

confidence: 93%

A Cyclic Nucleotide-Gated Channel (CNGC16) in Pollen Is Critical for Stress Tolerance in Pollen Reproductive Development

et al. 2012

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Cyclic nucleotide-gated channels (CNGCs) have been implicated in diverse aspects of plant growth and development, including responses to biotic and abiotic stress, as well as pollen tube growth and fertility. Here, genetic evidence identifies CNGC16 in Arabidopsis (Arabidopsis thaliana) as critical for pollen fertility under conditions of heat stress and drought. Two independent transfer DNA disruptions of cngc16 resulted in a greater than 10-fold stress-dependent reduction in pollen fitness and seed set. This phenotype was fully rescued through pollen expression of a CNGC16 transgene, indicating that cngc16-1 and 16-2 were both loss-of-function null alleles. The most stress-sensitive period for cngc16 pollen was during germination and the initiation of pollen tube tip growth. Pollen viability assays indicate that mutant pollen are also hypersensitive to external calcium chloride, a phenomenon analogous to calcium chloride hypersensitivities observed in other cngc mutants. A heat stress was found to increase concentrations of 39,59-cyclic guanyl monophosphate in both pollen and leaves, as detected using an antibody-binding assay. A quantitative PCR analysis indicates that cngc16 mutant pollen have attenuated expression of several heat-stress response genes, including two heat shock transcription factor genes, HsfA2 and HsfB1. Together, these results provide evidence for a heat stress response pathway in pollen that connects a cyclic nucleotide signal, a Ca 2+ -permeable ion channel, and a signaling network that activates a downstream transcriptional heat shock response.

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Adaptation of Mammalian Photoreceptors to Background Light: Putative Role for Direct Modulation of Phosphodiesterase

Cited by 23 publications

References 54 publications

Light-Induced Translocation of RGS9-1 and Gβ5L in Mouse Rod Photoreceptors

Light-Induced Translocation of RGS9-1 and Gβ5L in Mouse Rod Photoreceptors

Adaptation to steady light by intrinsically photosensitive retinal ganglion cells

A Cyclic Nucleotide-Gated Channel (CNGC16) in Pollen Is Critical for Stress Tolerance in Pollen Reproductive Development

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