studying-membrane-protein-trafficking-drosophila-photoreceptor-cells

Studying Membrane Protein Trafficking in <em>Drosophila</em> Photoreceptor Cells Using eGFP-Tagged Proteins

Membrane protein trafficking regulates the incorporation and removal of receptors and ion channels into the plasma membrane. This process is fundamentally ...

University of Hohenheim

The  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  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  eye as part of genetic screens, to study rhodopsin expression patterns, subcellular protein localization, membrane protein transport or as genetically encoded biosensors for Ca 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  photoreceptors may aid research in other sensory or neuronal systems that have not yet been studied as well as the  eye.

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

Plasma membrane protein trafficking is of fundamental importance for cell function and cell integrity of neurons and includes regulated protein recycling. In this work, we report a novel role of the endoplasmic reticulum (ER) for protein recycling as discovered in trafficking studies of the ion channel TRPL in photoreceptor cells of Drosophila. TRPL is located within the rhabdomeric membrane from where it is endocytosed upon light stimulation and stored in the cell body. Conventional immunohistochemistry as well as stimulated emission depletion super-resolution microscopy revealed TRPL storage at the ER after illumination, suggesting an unusual recycling route of TRPL. Our results also imply that both phospholipase D (PLD) and retromer complex are required for correct recycling of TRPL to the rhabdomeric membrane. Loss of PLD activity in PLD mutants results in enhanced degradation of TRPL. In the retromer mutant vps35 , TRPL is trapped in a Rab5-positive compartment. Evidenced by epistatic analysis in the double mutant PLD vps35 , PLD activity precedes retromer function. We propose a model in which PLD and retromer function play key roles in the transport of TRPL to an ER enriched compartment.

Article	Year
Application of Fluorescent Proteins for Functional Dissection of the Visual System. International journal of molecular sciences\| PubMed ID: 34445636	2021
Phospholipase D and retromer promote recycling of TRPL ion channel via the endoplasmic reticulum. Traffic (Copenhagen, Denmark)\| PubMed ID: 34719094	2022

Krystina Wagner

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