The Ciliary Lumen Accommodates Passive Diffusion and Vesicle Trafficking in Cytoplasmic-Ciliary Transport

Citations Over Time

Abstract

Abstract Transport of membrane and cytosolic proteins into the primary cilium is essential for its role in cellular signaling. Using single molecule microscopy, we mapped the movement of membrane and soluble proteins at the base of the primary cilium. In addition to the well-known intraflagellar transport (IFT) route, we identified two new pathways within the lumen of the primary cilium - passive diffusional and vesicle transport routes - that are adopted by proteins for cytoplasmic-cilium transport in live cells. Independent of the IFT path, approximately half of IFT motors (KIF3A) and cargo (α-tubulin) take the passive diffusion route and more than half of membrane-embedded G protein coupled receptors (SSTR3 and HTR6) use RAB8A-regulated vesicles to transport into and inside cilia. Furthermore, ciliary lumen transport is the preferred route for membrane proteins in the early stages of ciliogenesis and inhibition of SSTR3 vesicle transport completely blocks ciliogenesis. Furthermore, clathrin-mediated, signal-dependent internalization of SSTR3 also occurs through the ciliary lumen. These transport routes were also observed in Chlamydomonas reinhardtii flagella, suggesting their conserved roles in trafficking of ciliary proteins.

Related Papers

• → A motility in the eukaryotic flagellum unrelated to flagellar beating.(1993)1,002 cited
• → Intraflagellar Transport and Functional Analysis of Genes Required for Flagellum Formation in Trypanosomes(2007)190 cited
• → Regulation of flagellar length in Chlamydomonas(2008)53 cited
• → Chlamydomonas Basal Bodies as Flagella Organizing Centers(2018)34 cited
• → Purification and Localization of Intraflagellar Transport Particles and Polypeptides(2009)1 cited