Ciliary entry of the kinesin-2 motor KIF17 is regulated by importin-β2 and RanGTP

• Published in: Nature cell biology Vol. 12; no. 7; pp. 703 - 710
• Main Authors: Dishinger, John F., Kee, Hooi Lynn, Jenkins, Paul M., Fan, Shuling, Hurd, Toby W., Hammond, Jennetta W., Truong, Yen Nhu-Thi, Margolis, Ben, Martens, Jeffrey R., Verhey, Kristen J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2010; Nature Publishing Group
• Subjects: 631/80/128/1383; 631/80/128/2343; 631/80/389; Biological transport; Biomedical and Life Sciences; Cancer Research; Cell Biology; Cellular signal transduction; Cilia and ciliary motion; Developmental Biology; Kinesin; letter; Life Sciences; Physiological aspects; Stem Cells; United States
• ISSN: 1465-7392; 1476-4679
• DOI: 10.1038/ncb2073

How factors are targeted to cilia remains largely unknown. A ciliary localization signal targets the KIF17 motor, important for intraflagellar transport, to cilia through importin-β2 and RanGTP. The biogenesis, maintenance and function of primary cilia are controlled through intraflagellar transport (IFT) driven by two kinesin-2 family members, the heterotrimeric KIF3A/KIF3B/KAP complex and the homodimeric KIF17 motor 1 , 2 . How these motors and their cargoes gain access to the ciliary compartment is poorly understood. Here, we identify a ciliary localization signal (CLS) in the KIF17 tail domain that is necessary and sufficient for ciliary targeting. Similarities between the CLS and classic nuclear localization signals (NLSs) suggest that similar mechanisms regulate nuclear and ciliary import. We hypothesize that ciliary targeting of KIF17 is regulated by a ciliary-cytoplasmic gradient of the small GTPase Ran, with high levels of GTP-bound Ran (RanGTP) in the cilium. Consistent with this, cytoplasmic expression of GTP-locked Ran(G19V) disrupts the gradient and abolishes ciliary entry of KIF17. Furthermore, KIF17 interacts with the nuclear import protein importin-β2 in a manner dependent on the CLS and inhibited by RanGTP. We propose that Ran has a global role in regulating cellular compartmentalization by controlling the shuttling of cytoplasmic proteins into nuclear and ciliary compartments.