QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 30 May 2006
doi: 10.1242/jcs.02986

This Article Figures Only Full Text Full Text (PDF) Supplementary Material All Versions of this Article: jcs.02986v1 119/12/2592    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Meyer, N. E. Articles by Huber, A. Search for Related Content PubMed PubMed Citation Articles by Meyer, N. E. Articles by Huber, A.

Subcellular translocation of the eGFP-tagged TRPL channel in Drosophila photoreceptors requires activation of the phototransduction cascade

¹ Department of Biosensorics, Institute of Physiology, University of Hohenheim, 70599 Stuttgart, Germany
² Department of Physiology and The Kühne Minerva Center for Studies of Visual Transduction, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel

^* Author for correspondence (e-mail: Armin.Huber{at}uni-hohenheim.de)

Accepted 21 March 2006

Signal-mediated translocation of transient receptor potential (TRP) channels is a novel mechanism to fine tune a variety of signaling pathways including neuronal path finding and Drosophila photoreception. In Drosophila phototransduction the cation channels TRP and TRP-like (TRPL) are the targets of a prototypical G protein-coupled signaling pathway. We have recently found that the TRPL channel translocates between the rhabdomere and the cell body in a light-dependent manner. This translocation modifies the ion channel composition of the signaling membrane and induces long-term adaptation. However, the molecular mechanism underlying TRPL translocation remains unclear. Here we report that eGFP-tagged TRPL expressed in the photoreceptor cells formed functional ion channels with properties of the native channels, whereas TRPL-eGFP translocation could be directly visualized in intact eyes. TRPL-eGFP failed to translocate to the cell body in flies carrying severe mutations in essential phototransduction proteins, including rhodopsin, Gq, phospholipase Cß and the TRP ion channel, or in proteins required for TRP function. Our data, furthermore, show that the activation of a small fraction of rhodopsin and of residual amounts of the Gq protein is sufficient to trigger TRPL-eGFP internalization. In addition, we found that endocytosis of TRPL-eGFP occurs independently of dynamin, whereas a mutation of the unconventional myosin III, NINAC, hinders complete translocation of TRPL-eGFP to the cell body. Altogether, this study revealed that activation of the phototransduction cascade is mandatory for TRPL internalization, suggesting a critical role for the light induced conductance increase and the ensuing Ca²⁺-influx in the translocation process. The critical role of Ca²⁺ influx was directly demonstrated when the light-induced TRPL-eGFP translocation was blocked by removing extracellular Ca²⁺.

Key words: Drosophila, eGFP, Endocytosis, G Protein, Phototransduction, TRP channel

This article has been cited by other articles:

				J. Waguespack, F. T. Salles, B. Kachar, and A. J. Ricci Stepwise Morphological and Functional Maturation of Mechanotransduction in Rat Outer Hair Cells J. Neurosci., December 12, 2007; 27(50): 13890 - 13902. [Abstract] [Full Text] [PDF]