Membrane protein trafficking in Drosophila photoreceptor cells

Schopf, Krystina; Huber, Armin

doi:10.1016/j.ejcb.2016.11.002

Cited by 23 publications

(16 citation statements)

References 115 publications

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“…, 2007 ; Wang et al. , 2014b ; Schopf and Huber, 2017 ). Thus, in our analysis of wild-type animals, TRP localized exclusively to the rhabdomere, whereas Rh1 was found in small, cytoplasmic exocytic vesicles ( Figure 2A ).…”

Section: Resultsmentioning

confidence: 99%

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The V-ATPase V1 subunit A1 is required for rhodopsin anterograde trafficking inDrosophila

Zhao

Wang

2018

MBoC

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Synthesis and maturation of the light sensor, rhodopsin, are critical for the maintenance of light sensitivity and for photoreceptor homeostasis. In Drosophila, the main rhodopsin, Rh1, is synthesized in the endoplasmic reticulum and transported to the rhabdomere through the secretory pathway. In an unbiased genetic screen for factors involved in rhodopsin homeostasis, we identified mutations in vha68-1, which encodes the vacuolar proton-translocating ATPase (V-ATPase) catalytic subunit A isoform 1 of the V1 component. Loss of vha68-1 in photoreceptor cells disrupted post-Golgi anterograde trafficking of Rh1, reduced light sensitivity, increased secretory vesicle pH, and resulted in incomplete Rh1 deglycosylation. In addition, vha68-1 was required for activity-independent photoreceptor cell survival. Importantly, vha68-1 mutants exhibited phenotypes similar to those exhibited by mutations in the V0 component of V-ATPase, vha100-1. These data demonstrate that the V1 and V0 components of V-ATPase play key roles in post-Golgi trafficking of Rh1 and that Drosophila may represent an important animal model system for studying diseases associated with V-ATPase dysfunction.

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Section: Resultsmentioning

confidence: 99%

“…Proper targeting of Rh1 to the rhabdomere is crucial for normal phototransduction and photoreceptor cell survival ( Colley et al. , 1995 ; Xiong and Bellen, 2013 ; Schopf and Huber, 2017 ). A wide array of chaperones within the ER ensure proper biosynthesis and folding of rhodopsin ( Colley et al.…”

Section: Introductionmentioning

confidence: 99%

The V-ATPase V1 subunit A1 is required for rhodopsin anterograde trafficking inDrosophila

Zhao

Wang

2018

MBoC

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“…Drosophila photoreceptor neurons utilize the fastest phospholipid signaling cascade and exhibit high rates of membrane trafficking. Therefore, it is particularly important for neurons to maintain phospholipid pools [ 23 , 46 ]. As phototransduction is completely mediated by phospholipase C (PLC), maintaining levels of PIP 2 and its product DAG are critical for visual responses [ 24 , 47 ].…”

Section: Discussionmentioning

confidence: 99%

PE homeostasis rebalanced through mitochondria-ER lipid exchange prevents retinal degeneration in Drosophila

Zhao

Wang

2020

PLoS Genet

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The major glycerophospholipid phosphatidylethanolamine (PE) in the nervous system is essential for neural development and function. There are two major PE synthesis pathways, the CDP-ethanolamine pathway in the endoplasmic reticulum (ER) and the phosphatidylserine decarboxylase (PSD) pathway in mitochondria. However, the role played by mitochondrial PE synthesis in maintaining cellular PE homeostasis is unknown. Here, we show that Drosophila pect (phosphoethanolamine cytidylyltransferase) mutants lacking the CDP-ethanolamine pathway, exhibited alterations in phospholipid composition, defective phototransduction, and retinal degeneration. Induction of the PSD pathway fully restored levels and composition of cellular PE, thus rescued the retinal degeneration and defective visual responses in pect mutants. Disrupting lipid exchange between mitochondria and ER blocked the ability of PSD to rescue pect mutant phenotypes. These findings provide direct evidence that the synthesis of PE in mitochondria contributes to cellular PE homeostasis, and suggest the induction of mitochondrial PE synthesis as a promising therapeutic approach for disorders associated with PE deficiency.

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“…In this study, we showed the first evidence that Gαq3 regulates Rh1 synthesis. Rh1 is transported to the plasma membrane by vesicular transport mechanisms regulated by a large number of trafficking proteins (31)(32)(33)(34)(35). Previous studies have shown that Gαq homologue CG30054 regulates inositol 1,4,5,-tris-phosphate receptor (IP3R) to mediate calcium mobilization from intracellular stores and promote calcium-regulated secretory vesicle exocytosis (36).…”

Section: Gαq3 Isoforms Regulate Rh1 Synthesismentioning

confidence: 99%

Gαq splice variants mediate phototransduction, rhodopsin synthesis, and retinal integrity in Drosophila

Tian

et al. 2020

Journal of Biological Chemistry

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Heterotrimeric G proteins mediate a variety of signaling processes by coupling G protein–coupled receptors to intracellular effector molecules. In Drosophila, the Gαq gene encodes several Gαq splice variants, with the Gαq1 isoform protein playing a major role in fly phototransduction. However, Gαq1 null mutant flies still exhibit a residual light response, indicating that other Gαq splice variants or additional Gq α subunits are involved in phototransduction. Here, we isolated a mutant fly with no detectable light responses, decreased rhodopsin (Rh) levels, and rapid retinal degeneration. Using electrophysiological and genetic studies, biochemical assays, immunoblotting, real-time RT-PCR, and EM analysis, we found that mutations in the Gαq gene disrupt light responses and demonstrate that the Gαq3 isoform protein is responsible for the residual light response in Gαq1 null mutants. Moreover, we report that Gαq3 mediates rhodopsin synthesis. Depletion of all Gαq splice variants led to rapid light-dependent retinal degeneration, due to the formation stable Rh1-arrestin 2 (Arr2) complexes. Our findings clarify essential roles of several different Gαq splice variants in phototransduction and retinal integrity in Drosophila and reveal that Gαq3 functions in rhodopsin synthesis.

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Membrane protein trafficking in Drosophila photoreceptor cells

Cited by 23 publications

References 115 publications

The V-ATPase V1 subunit A1 is required for rhodopsin anterograde trafficking inDrosophila

The V-ATPase V1 subunit A1 is required for rhodopsin anterograde trafficking inDrosophila

PE homeostasis rebalanced through mitochondria-ER lipid exchange prevents retinal degeneration in Drosophila

Gαq splice variants mediate phototransduction, rhodopsin synthesis, and retinal integrity in Drosophila

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