In Vivo Analysis of the Drosophila Light-Sensitive Channels, TRP and TRPL

Reuß, Helmut; Mojet, MH; Chyb, Sylwester; Hardie, Roger C.

doi:10.1016/s0896-6273(00)80416-x

Cited by 175 publications

(231 citation statements)

References 36 publications

(10 reference statements)

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“…In addition, the trpl mutant displays a defect in adapting to dim background illumination [140]. Upon elimination of both trp and trpl, the flies are unresponsive to light [9,141].…”

Section: The Trpc Cation Channelsmentioning

confidence: 99%

“…TRP would appear to be present primarily as a homomultimer since it is ∼10-fold more abundant than TRPL [142]. Analyses of TRP in the absence of TRPL (analyzed in the trpl mutant) indicates that the TRP-dependent current is relatively Ca 2+ selective (P Ca :P Na =100:1), with a conductance of 4 pS [141]. The TRPL-dependent current (analyzed in the trp mutant) is nonselective (P Ca :P Na =4.1) and has a higher conductance than TRP (35 pS) [141].…”

Section: The Trpc Cation Channelsmentioning

confidence: 99%

“…Analyses of TRP in the absence of TRPL (analyzed in the trpl mutant) indicates that the TRP-dependent current is relatively Ca 2+ selective (P Ca :P Na =100:1), with a conductance of 4 pS [141]. The TRPL-dependent current (analyzed in the trp mutant) is nonselective (P Ca :P Na =4.1) and has a higher conductance than TRP (35 pS) [141]. Evidence that TRP and TRPL interact is that they coimmunoprecipitate from fly head extracts and interact in vitro [142].…”

Section: The Trpc Cation Channelsmentioning

confidence: 99%

“…TRPL is constitutively active in vitro; however, TRP/TRPL heteromultimers are regulated channels [142]. However, it has been argued that TRP and TRPL function as two independent homomultimers since the wild-type conductance can be accounted for by the summation of the conductances in the trp and trpl mutants [141]. An additional possibility is that the channels consist of TRP and TRPL homomultimers and TRP/TRPL heteromultimers.…”

Section: The Trpc Cation Channelsmentioning

confidence: 99%

“…If the flies are kept for long periods in the light, the light-dependent conductance is due almost completely to TRP. Since the Ca 2+ selectivity of TRP is much higher than TRPL [141], this change in ratio of TRP and TRPL has physiological consequences. Dark-raised wild-type flies, which have the maximal level of rhabdomeral TRPL, are more sensitive to dim background lights than wild-type flies kept in the light or trpl flies maintained in the dark [185].…”

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 99%

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Phototransduction and retinal degeneration in Drosophila

Wang

Montell

2007

Pflugers Arch - Eur J Physiol

257

303

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Drosophila visual transduction is the fastest known G-protein-coupled signaling cascade and has therefore served as a genetically tractable animal model for characterizing rapid responses to sensory stimulation. Mutations in over 30 genes have been identified, which affect activation, adaptation, or termination of the photoresponse. Based on analyses of these genes, a model for phototransduction has emerged, which involves phosphoinoside signaling and culminates with opening of the TRP and TRPL cation channels. Many of the proteins that function in phototransduction are coupled to the PDZ containing scaffold protein INAD and form a supramolecular signaling complex, the signalplex. Arrestin, TRPL, and Gα q undergo dynamic light-dependent trafficking, and these movements function in long-term adaptation. Other proteins play important roles either in the formation or maturation of rhodopsin, or in regeneration of phosphatidylinositol 4,5-bisphosphate (PIP 2 ), which is required for the photoresponse. Mutation of nearly any gene that functions in the photoresponse results in retinal degeneration. The underlying bases of photoreceptor cell death are diverse and involve mechanisms such as excessive endocytosis of rhodopsin due to stable rhodopsin/arrestin complexes and abnormally low or high levels of Ca 2+ . Drosophila visual transduction appears to have particular relevance to the cascade in the intrinsically photosensitive retinal ganglion cells in mammals, as the photoresponse in these latter cells appears to operate through a remarkably similar mechanism.

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“…In addition, the trpl mutant displays a defect in adapting to dim background illumination [140]. Upon elimination of both trp and trpl, the flies are unresponsive to light [9,141].…”

Section: The Trpc Cation Channelsmentioning

confidence: 99%

Section: The Trpc Cation Channelsmentioning

confidence: 99%

Section: The Trpc Cation Channelsmentioning

confidence: 99%

Section: The Trpc Cation Channelsmentioning

confidence: 99%

Section: Long-term Adaptation Through Light-dependent Translocation Omentioning

confidence: 99%

See 3 more Smart Citations

Phototransduction and retinal degeneration in Drosophila

Wang

Montell

2007

Pflugers Arch - Eur J Physiol

257

303

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Phototransduction mechanisms in Drosophila microvillar photoreceptors

Hardie

2011

WIREs Membr Transp Signal

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Phototransduction in Drosophila is mediated by a G-protein coupled phospholipase C (PLC) cascade leading to graded membrane depolarization. It is the preferred model for phototransduction in microvillar photoreceptors and an important model for the ubiquitous phosphoinositide signaling cascade. The photoreceptors respond sensitively to single photons 10-100× more rapidly than vertebrate rods, yet still light adapt to signal under full sunlight. Incident light is absorbed and transduced in the rhabdomere, a 1-2 µm diameter, 100 µm long waveguide composed of ∼30,000 tightly packed microvilli, which contain the visual pigment rhodopsin and all the major components of the cascade. PLC hydrolyzes phosphatidyl-inositol (4,5) bisphosphate (PIP 2 ) to generate diacylglycerol (DAG), inositol (1,4,5) trisphosphate (InsP 3 ), and also a proton. This results in activation of two classes of Ca 2+ permeable cation channels, TRP and TRPL-the prototypical members of the transient receptor potential (TRP) superfamily of cation channels. Recent evidence suggests that the channels may be activated in a combinatorial manner by two neglected consequences of PLC activity, namely simultaneous depletion of PIP 2 and acidification. Several components of the cascade, including TRP, PLC, and protein kinase C are assembled into multimolecular signaling complexes by the PDZ-domain scaffolding protein INAD. Ca 2+ influx via TRP channels is essential for rapid kinetics, amplification, and light adaptation and mediates both positive and negative feedback via multiple downstream targets, including the channels, rhodopsin, and PLC. This Ca 2+ -dependent feedback along with the ultracompartmentalization provided by the microvillar design and molecular scaffolding is critical for the combination of sensitivity, rapid kinetics, and broad dynamic range. 

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