title: Signals governing the trafficking and mistrafficking of a ciliary GPCR, rhodopsin.
abstract: Rhodopsin is a cilia-specific GPCR essential for vision. Rhodopsin mislocalization is associated with blinding diseases called retinal ciliopathies. The mechanism by which rhodopsin mislocalizes in rod photoreceptor neurons is not well understood. Therefore, we investigated the roles of trafficking signals in rhodopsin mislocalization. Rhodopsin and its truncation mutants were fused to a photoconvertible fluorescent protein, Dendra2, and expressed in Xenopus laevis rod photoreceptors. Photoconversion of Dendra2 causes a color change from green to red, enabling visualization of the dynamic events associated with rhodopsin trafficking and renewal. We found that rhodopsin mislocalization is a facilitated process for which a signal located within 322-326 aa (CCGKN) is essential. An additional signal within 327-336 aa further facilitated the mislocalization. This collective mistrafficking signal confers toxicity to rhodopsin and causes mislocalization when the VXPX cilia-targeting motif is absent. We also determined that the VXPX motif neutralizes this mistrafficking signal, enhances ciliary targeting at least 10-fold, and accelerates trafficking of post-Golgi vesicular structures. In the absence of the VXPX motif, mislocalized rhodopsin is actively cleared through secretion of vesicles into the extracellular milieu. Therefore, this study unveiled the multiple roles of trafficking signals in rhodopsin localization and renewal.
authors: Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
authors: Kerrie H
authors: KH
authors: Lodowski
authors: Richard
authors: R
authors: Lee
authors: Philip
authors: P
authors: Ropelewski
authors: Ina
authors: I
authors: Nemet
authors: Guilian
authors: G
authors: Tian
authors: Yoshikazu
authors: Y
authors: Imanishi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001001:Anura; D005123:Eye / Q000033:anatomy & histology; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009924:Organ Culture Techniques; D010775:Photic Stimulation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000235:genetics*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D008164:Luminescent Proteins; D043562:Receptors, G-Protein-Coupled; D012243:Rhodopsin; D000254:Sodium-Potassium-Exchanging ATPase
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