Unitary Recordings of TRP and TRPL Channels From Isolated <i>Drosophila</i> Retinal Photoreceptor Rhabdomeres: Activation by Light and Lipids

Delgado, Ricardo; Bacigalupo, Juan

doi:10.1152/jn.90578.2008

Cited by 40 publications

(50 citation statements)

References 31 publications

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“…As a negative control we tested DAG in the double mutant lacking both channels, trp;trpl. As expected these patches were silent when excised in the light (Delgado and Bacigalupo, 2009), even in the presence of DAG ( Fig. 2B; n ϭ 6).…”

Section: Atp Lowers Channel Activity In Active Patchessupporting

confidence: 83%

“…1A), those excised in the light exhibited a pronounced constitutive TRP activity ( Fig. 1B; n Ͼ100; Delgado and Bacigalupo, 2009). These observations suggest that the channel remained indefinitely in the mode it was in at the time of excision, open or closed.…”

Section: Atp Lowers Channel Activity In Active Patchesmentioning

confidence: 89%

“…We previously observed that adding millimolar ATP to the solution bathing the cytoplasmic side of the patch drastically decreased TRP and TRPL activity in excised patches (Delgado and Bacigalupo, 2009). This closely resembles the physiological situation, where PLC generates DAG, which is subsequently phosphorylated to phosphatidic acid by DGK.…”

Section: Atp Lowers Channel Activity In Active Patchesmentioning

confidence: 98%

“…PUFAs and DAG open TRP and TRPL from the cytoplasmic side of excised rhabdomeral membrane patches (Delgado and Bacigalupo, 2009). DAG and PUFA applications to heterologously expressed TRPL have yielded conflicting results, since its basal activity and responsiveness to these lipids varies with the expression system (Lev et al, 2012a).…”

Section: Introductionmentioning

confidence: 99%

“…Eyes were removed from adult flies of either sex and their retinae mechanically disrupted with a sharp tungsten wire under low divalent cation Drosophila Ringer's solution containing the following (in mM): 120 NaCl, 4 KCl, 1 EGTA, 0.7 mM CaCl 2 , 10 HEPES, 2.5 L-proline, and 25 sucrose, pH 7.15. Ommatidia with partly disaggregated photoreceptors resulting from this procedure were chosen for the experiments, as the terminal segments of their rhabdomeres became exposed and were clearly identifiable by their distinctive brightness (Delgado and Bacigalupo, 2009). The cells were viewed with an Olympus IX70 inverted microscope, using either DIC optics (60ϫ objective) or phase contrast (100ϫ objective, NA 1.25).…”

Section: Introductionmentioning

confidence: 99%

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Diacylglycerol Activates the Light-Dependent Channel TRP in the Photosensitive Microvilli ofDrosophila melanogasterPhotoreceptors

et al. 2014

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Section: Atp Lowers Channel Activity In Active Patchessupporting

confidence: 83%

Section: Atp Lowers Channel Activity In Active Patchesmentioning

confidence: 89%

Section: Atp Lowers Channel Activity In Active Patchesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Diacylglycerol Activates the Light-Dependent Channel TRP in the Photosensitive Microvilli ofDrosophila melanogasterPhotoreceptors

et al. 2014

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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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Photosensitive TRPs

Hardie

2014

Handbook of Experimental Pharmacology

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The Drosophila "transient receptor potential" channel is the prototypical TRP channel, belonging to and defining the TRPC subfamily. Together with a second TRPC channel, trp-like (TRPL), TRP mediates the transducer current in the fly's photoreceptors. TRP and TRPL are also implicated in olfaction and Malpighian tubule function. In photoreceptors, TRP and TRPL are localised in the ~30,000 packed microvilli that form the photosensitive "rhabdomere"-a light-guiding rod, housing rhodopsin and the rest of the phototransduction machinery. TRP (but not TRPL) is assembled into multimolecular signalling complexes by a PDZ-domain scaffolding protein (INAD). TRPL (but not TRP) undergoes light-regulated translocation between cell body and rhabdomere. TRP and TRPL are also found in photoreceptor synapses where they may play a role in synaptic transmission. Like other TRPC channels, TRP and TRPL are activated by a G protein-coupled phospholipase C (PLCβ4) cascade. Although still debated, recent evidence indicates the channels can be activated by a combination of PIP2 depletion and protons released by the PLC reaction. PIP2 depletion may act mechanically as membrane area is reduced by cleavage of PIP2's bulky inositol headgroup. TRP, which dominates the light-sensitive current, is Ca(2+) selective (P Ca:P Cs >50:1), whilst TRPL has a modest Ca(2+) permeability (P Ca:P Cs ~5:1). Ca(2+) influx via the channels has profound positive and negative feedback roles, required for the rapid response kinetics, with Ca(2+) rapidly facilitating TRP (but not TRPL) and also inhibiting both channels. In trp mutants, stimulation by light results in rapid depletion of microvillar PIP2 due to lack of Ca(2+) influx required to inhibit PLC. This accounts for the "transient receptor potential" phenotype that gives the family its name and, over a period of days, leads to light-dependent retinal degeneration. Gain-of-function trp mutants with uncontrolled Ca(2+) influx also undergo retinal degeneration due to Ca(2+) cytotoxicity. In vertebrate retina, mice knockout studies suggest that TRPC6 and TRPC7 mediate a PLCβ4-activated transducer current in intrinsically photosensitive retinal ganglion cells, expressing melanopsin. TRPA1 has been implicated as a "photo-sensing" TRP channel in human melanocytes and light-sensitive neurons in the body wall of Drosophila.

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Unitary Recordings of TRP and TRPL Channels From Isolated Drosophila Retinal Photoreceptor Rhabdomeres: Activation by Light and Lipids

Cited by 40 publications

References 31 publications

Diacylglycerol Activates the Light-Dependent Channel TRP in the Photosensitive Microvilli ofDrosophila melanogasterPhotoreceptors

Diacylglycerol Activates the Light-Dependent Channel TRP in the Photosensitive Microvilli ofDrosophila melanogasterPhotoreceptors

Phototransduction mechanisms in Drosophila microvillar photoreceptors

Photosensitive TRPs

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