Ca2+ Signaling in Drosophila Photoreceptor Cells

Voolstra, Olaf; Huber, Armin

doi:10.1007/978-3-030-12457-1_34

Cited by 14 publications

(8 citation statements)

References 106 publications

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“…Photoreceptors are unique in that they have evolved mechanisms responsible for maintaining homeostasis in the presence of light-induced calcium ion gradients that are magnitudes greater than what other neuronal populations experience [17, 18]. Mechanisms of light adaptation within photoreceptors include the rapid (millisecond) closure of TRP channels (facilitated via enzymes scaffolded by inaD ), rhodopsin internalization from the rhabdomere membrane (e.g., arr1 , arr2 ), and calcium efflux (e.g., calx ) [19, 20]. Acrophase analyses (i.e., time of peak expression) revealed that circadian transcripts that promote photoreceptor activation (Ca 2+ influx) reach peak expression during the dark-phase, while genes that terminate the phototransduction response (i.e., deactivation of rhodopsin mediated signaling) peak in anticipation of the light-phase ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Dietary restriction andclockdelay eye aging to extend lifespan inD. melanogaster

Hodge

Meyerhof

Katewa

et al. 2021

Preprint

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Many vital processes in the eye are under circadian regulation, and circadian dysfunction has emerged as a potential driver of eye aging. Dietary restriction is one of the most robust lifespan-extending therapies and amplifies circadian rhythms with age. Herein, we demonstrate that dietary restriction extends lifespan in D. melanogaster by promoting circadian homeostatic processes that protect the visual system from age- and light-associated damage. Disrupting circadian rhythms in the eye by inhibiting the transcription factor, Clock (CLK), or CLK-output genes, accelerated visual senescence, induced a systemic immune response, and shortened lifespan. Flies subjected to dietary restriction were protected from the lifespan-shortening effects of photoreceptor activation. Inversely, photoreceptor inactivation, achieved via mutating rhodopsin or housing flies in constant darkness, primarily extended lifespan in flies reared on a high-nutrient diet. Our findings establish the eye as a diet-sensitive modulator of lifespan and indicate that vision is an antagonistically pleiotropic process that contributes to organismal aging.

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Section: Resultsmentioning

confidence: 99%

Dietary restriction andclockdelay eye aging to extend lifespan inD. melanogaster

Hodge

Meyerhof

Katewa

et al. 2021

Preprint

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“…In Drosophila photoreceptors, activation of rhodopsin leads to a transient rise of cytoplasmic Ca 2+ , which has been implicated in regulating the visual response and in maintaining the structural integrity of photoreceptors (Voolstra and Huber, 2020). The Ca 2+ transient thereby activates several protein kinases including the Ca 2+ /calmodulin-dependent protein kinase II and PKC.…”

Section: Resultsmentioning

confidence: 99%

Transmembrane Signaling Regulates the Remodeling of the Actin Cytoskeleton: Roles of PKC and Adducin

Shieh

Sun

Ferng

2021

Preprint

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Members of the conventional protein kinase C (cPKC) family are activated by both DAG and Ca2+ and have been implicated in the regulation of the actin cytoskeleton. Drosophila contains two cPKCs, Pkc53E (Pkc1) and eye-PKC (Pkc2); mutants missing each PKC lead to retinal degeneration. While eye-PKC is critical for the visual signaling, the role of Pkc53E is not known. We identified a photoreceptor-specific isoform of Pkc53E and show Pkc53E-RNAi negatively impacts the actin cytoskeleton of rhabdomeres. Interestingly, Pkc53E-RNAi enhances the degeneration of norpAP24 photoreceptors, suggesting Pkc53E could be activated independently of NorpA/PLCβ4. We further demonstrate that in norpAP24 photoreceptors Plc21C can be activated by Gq, which is responsible for the activation of Pkc53E. We explored whether Pkc53E regulates adducin in Drosophila photoreceptors. Adducin cross-links the actin cytoskeleton to the spectrin network, which is blunted by PKC phosphorylation. Importantly, we observed that phosphorylation of adducin was greatly reduced in a null allele of pkc53E. Downregulation of hts that encodes Drosophila adducin, exerts a more severe effect than Pkc53E-RNAi to impact the actin cytoskeleton. In contrast, overexpression of a mCherry tagged Add2, one of the three Drosophila adducin isoforms, led to the apical expansion of rhabdomeres with overgrowth of the actin cytoskeleton. This phenotype is likely caused by the dominant-negative activity of the tagged Add2 as it also was observed in α-spectrin-RNAi or β-spectrin-RNAi. Interestingly, downregulation of Pkc53E does not suppress the expansion of rhabdomeres during development, but negatively affects the appearance of rhabdomeres in adult photoreceptors. We conclude that Drosophila adducin has two distinct functions: in pupal photoreceptors, it regulates rhabdomere morphogenesis, which is independent of Pkc53E. In adult photoreceptors, it promotes the maintenance of the actin cytoskeleton, which is regulated by Pkc53E in response to the light-induced activation of the PLCβ activity.

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“…Cleavage of PI(4,5)P 2 also generates protons, measurable changes in the microvillar structure and is responsible for gating the ion channels TRP and TRPL in the rhabdomeral membrane, resulting in Na + and Ca 2+ influx and depolarization of the PRC. Changes in Ca 2+ concentration then feed back onto numerous regulatory mechanisms, for example inactivation of rhodopsin, positive and negative regulation of TRP channels as well as short-and long-term light-adaptation [66]. The deactivation of the cascade as well as conservation and replenishing of the PI(4,5)P 2 pool via negative feedback, the phosphoinositide cycle and vesicular membrane traffic are subject of ongoing research.…”

Section: Fluorescence Proteins In Functional Studies Of the Drosophila Visual Systemmentioning

confidence: 99%

Application of Fluorescent Proteins for Functional Dissection of the Drosophila Visual System

Smylla

Wagner

Huber

2021

IJMS

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The Drosophila eye has been used extensively to study numerous aspects of biological systems, for example, spatio-temporal regulation of differentiation, visual signal transduction, protein trafficking and neurodegeneration. Right from the advent of fluorescent proteins (FPs) near the end of the millennium, heterologously expressed fusion proteins comprising FPs have been applied in Drosophila vision research not only for subcellular localization of proteins but also for genetic screens and analysis of photoreceptor function. Here, we summarize applications for FPs used in the Drosophila eye as part of genetic screens, to study rhodopsin expression patterns, subcellular protein localization, membrane protein transport or as genetically encoded biosensors for Ca2+ and phospholipids in vivo. We also discuss recently developed FPs that are suitable for super-resolution or correlative light and electron microscopy (CLEM) approaches. Illustrating the possibilities provided by using FPs in Drosophila photoreceptors may aid research in other sensory or neuronal systems that have not yet been studied as well as the Drosophila eye.

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Ca2+ Signaling in Drosophila Photoreceptor Cells

Cited by 14 publications

References 106 publications

Dietary restriction andclockdelay eye aging to extend lifespan inD. melanogaster

Dietary restriction andclockdelay eye aging to extend lifespan inD. melanogaster

Transmembrane Signaling Regulates the Remodeling of the Actin Cytoskeleton: Roles of PKC and Adducin

Application of Fluorescent Proteins for Functional Dissection of the Drosophila Visual System

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