RT Journal Article
SR Electronic
T1 The Ciliary Lumen Accommodates Passive Diffusion and Vesicle Trafficking in Cytoplasmic-Ciliary Transport
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 704213
DO 10.1101/704213
A1 Andrew Ruba
A1 Wangxi Luo
A1 Jingjie Yu
A1 Daisuke Takao
A1 Athanasios Evangelou
A1 Rachel Higgins
A1 Saovleak Khim
A1 Kristen J. Verhey
A1 Weidong Yang
YR 2019
UL http://biorxiv.org/content/early/2019/07/16/704213.abstract
AB 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.