In VivoIdentification and Manipulation of the Ca2+Selectivity Filter in theDrosophilaTransient Receptor Potential Channel

Liu, Che H.; Wang, Tao; Postma, Marten; Obukhov, Alexander G.; Montell, Craig; Hardie, Roger C.

doi:10.1523/jneurosci.4099-06.2007

Cited by 51 publications

(49 citation statements)

References 57 publications

(60 reference statements)

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“…Previous studies had implicated reduced Ca 2+ influx (Liu et al, 2007;Wang et al, 2005) and subsequent defects in the visual pigment cycle leading to degeneration via accumulation of M PP -Arr2 complexes (Wang et al, 2005). However, the present study revealed an alternative Ca 2+ -dependent mechanism, independent of the pigment cycle, and which can be studied in isolation by rearing flies under red light.…”

Section: Discussioncontrasting

confidence: 51%

“…) that eliminated Ca 2+ permeation (while still allowing Na + influx) resulted in a severe retinal degeneration phenotype (Liu et al, 2007). The M PP -Arr2 pathway was suggested to induce degeneration in trp mutants, because arr2 mutations partially suppressed the degeneration (Wang et al, 2005).…”

Section: D621gmentioning

confidence: 99%

“…Light-dependent retinal degeneration in Drosophila trp mutants was first reported 40 years ago (Cosens and Perry, 1972), and later hypothesised to be due to impaired Ca 2+ influx (Liu et al, 2007;Wang et al, 2005). In Drosophila, retinal degeneration due to reduced Ca 2+ levels is usually attributed to defects in the Ca 2+ -dependent visual pigment cycle.…”

Section: Introductionmentioning

confidence: 99%

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Depletion of PtdIns(4,5)P2 underlies retinal degeneration in Drosophila trp mutants

Sengupta

Barber

Xia

et al. 2013

Journal of Cell Science

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SummaryThe prototypical transient receptor potential (TRP) channel is the major light-sensitive, and Ca 2+ -permeable channel in the microvillar photoreceptors of Drosophila. TRP channels are activated following hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P 2 ] by the key effector enzyme phospholipase C (PLC). Mutants lacking TRP channels undergo light-dependent retinal degeneration, as a consequence of the reduced Ca 2+ influx. It has been proposed that degeneration is caused by defects in the Ca 2+ -dependent visual pigment cycle, which result in accumulation of toxic phosphorylated metarhodopsin-arrestin complexes (M PP -Arr2). Here we show that two interventions, which prevent accumulation of M PP -Arr2, namely rearing under red light or eliminating the C-terminal rhodopsin phosphorylation sites, failed to rescue degeneration in trp mutants. Instead, degeneration in trp mutants reared under red light was rescued by mutation of PLC. Degeneration correlated closely with the light-induced depletion of PtdIns(4,5)P 2 that occurs in trp mutants due to failure of Ca 2+ -dependent inhibition of PLC. Severe retinal degeneration was also induced in the dark in otherwise wild-type flies by overexpression of a bacterial PtdInsP n phosphatase (SigD) to deplete PtdIns(4,5)P 2 . In degenerating trp photoreceptors, phosphorylated Moesin, a PtdIns(4,5)P 2 -regulated membrane-cytoskeleton linker essential for normal microvillar morphology, was found to delocalize from the rhabdomere and there was extensive microvillar actin depolymerisation. The results suggest that compromised light-induced Ca 2+ influx, due to loss of TRP channels, leads to PtdIns(4,5)P 2 depletion, resulting in dephosphorylation of Moesin, actin depolymerisation and disintegration of photoreceptor structure.

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Section: Discussioncontrasting

confidence: 51%

Section: D621gmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Depletion of PtdIns(4,5)P2 underlies retinal degeneration in Drosophila trp mutants

Sengupta

Barber

Xia

et al. 2013

Journal of Cell Science

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“…), lacking the TRP channel, and of the trpl 302 null mutant, lacking the TRPL channel, revealed different biophysical properties of TRP and TRPL in vivo (Delgado and Bacigalupo, 2009;Hardie and Minke, 1994;Hardie and Mojet, 1995;Liu et al, 2007;Raghu et al, 2000;Reuss et al, 1997). Furthermore, the light response is completely abolished in the trpl 302 ;trp P343 double null mutant, indicating that both channels are necessary for the response to light (Niemeyer et al, 1996).…”

Section: P343mentioning

confidence: 95%

TheDrosophilaTRP and TRPL are assembled as homomultimeric channels in vivo

Katz¹,

Oberacker²,

Richter³

et al. 2013

Journal of Cell Science

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SummaryFamily members of the cationic transient receptor potential (TRP) channels serve as sensors and transducers of environmental stimuli. The ability of different TRP channel isoforms of specific subfamilies to form heteromultimers and the structural requirements for channel assembly are still unresolved. Although heteromultimerization of different mammalian TRP channels within single subfamilies has been described, even within a subfamily (such as TRPC) not all members co-assemble with each other. In Drosophila photoreceptors two TRPC channels, TRP and TRP-like protein (TRPL) are expressed together in photoreceptors where they generate the light-induced current. The formation of functional TRP-TRPL heteromultimers in cell culture and in vitro has been reported. However, functional in vivo assays have shown that each channel functions independently of the other. Therefore, the issue of whether TRP and TRPL form heteromultimers in vivo is still unclear. In the present study we investigated the ability of TRP and TRPL to form heteromultimers, and the structural requirements for channel assembly, by studying assembly of GFP-tagged TRP and TRPL channels and chimeric TRP and TRPL channels, in vivo. Interaction studies of tagged and native channels as well as native and chimeric TRP-TRPL channels using coimmunoprecipitation, immunocytochemistry and electrophysiology, critically tested the ability of TRP and TRPL to interact. We found that TRP and TRPL assemble exclusively as homomultimeric channels in their native environment. The above analyses revealed that the transmembrane regions of TRP and TRPL do not determine assemble specificity of these channels. However, the C-terminal regions of both TRP and TRPL predominantly specify the assembly of homomeric TRP and TRPL channels.

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“…Furthermore, it is probable that in Malpighian tubule, TRPL-TPPL homomultimers or TRPL/TRPgamma multimers are formed, which allow normal tubule function in the trp null background. A novel mutant of trp in which the calcium pore selectivity was modified by a Asp621 mutation, thus eliminating calcium permeation in vivo and resulting in altered photoresponses and retinal degeneration (Liu et al, 2007), was without effect on tubule secretion rates (P. Cabrero, S.A.D. and R. C. Hardie, data not shown).…”

Section: Trp Channelsmentioning

confidence: 98%

Organellar calcium signalling mechanisms inDrosophilaepithelial function

Davies

Terhzaz

2009

Journal of Experimental Biology

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SummaryCalcium signalling and calcium homeostasis are essential for life. Studies of calcium signalling thus constitute a major proportion of research in the life sciences, although the majority of these studies are based in cell lines or isolated cells. Epithelial cells and tissues are essential in the regulation of critical physiological processes, including fluid transport; and so the modulation of such processes in vivo by cell-specific calcium signalling is thus of interest. In this review, we describe the approaches to measuring intracellular calcium in the genetically tractable fluid-transporting tissue, the Drosophila Malpighian tubule by targeting cellspecific protein-based calcium reporters to defined regions, cells and intracellular compartments of the intact Malpighian tubule. We also discuss recent findings on the roles of plasma membrane and intracellular calcium channels; and on organellar storesincluding mitochondria, Golgi and peroxisomes -in Malpighian tubule function.

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In VivoIdentification and Manipulation of the Ca²⁺Selectivity Filter in theDrosophilaTransient Receptor Potential Channel

Cited by 51 publications

References 57 publications

Depletion of PtdIns(4,5)P2 underlies retinal degeneration in Drosophila trp mutants

Depletion of PtdIns(4,5)P2 underlies retinal degeneration in Drosophila trp mutants

TheDrosophilaTRP and TRPL are assembled as homomultimeric channels in vivo

Organellar calcium signalling mechanisms inDrosophilaepithelial function

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