A septin diffusion barrier at the base of the primary cilium maintains ciliary membrane protein distribution.
In animal cells, the primary cilium transduces extracellular signals through signaling receptors localized in the ciliary membrane, but how these ciliary membrane proteins are retained in the cilium is unknown. We found that ciliary membrane proteins were highly mobile, but their diffusion was impeded at the base of the cilium by a diffusion barrier. Septin 2 (SEPT2), a member of the septin family of guanosine triphosphatases that form a diffusion barrier in budding yeast, localized at the base of the ciliary membrane. SEPT2 depletion resulted in loss of ciliary membrane protein localization and Sonic hedgehog signal transduction, and inhibited ciliogenesis. Thus, SEPT2 is part of a diffusion barrier at the base of the ciliary membrane and is essential for retaining receptor-signaling pathways in the primary cilium.
Hu
Qicong
Q
Department of Biology, Stanford University, Stanford, CA 94305, USA.
Milenkovic
Ljiljana
L
Jin
Hua
H
Scott
Matthew P
MP
Nachury
Maxence V
MV
Spiliotis
Elias T
ET
Nelson
W James
WJ
D000818:Animals; D054468:Axoneme / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D002923:Cilia / Q000378:metabolism* / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004058:Diffusion; D036681:Fluorescence Recovery After Photobleaching; D019204:GTP-Binding Proteins / Q000378:metabolism*; D053823:Hedgehog Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D011985:Receptors, Serotonin / Q000378:metabolism; D017481:Receptors, Somatostatin / Q000378:metabolism; D058112:Septins; D015398:Signal Transduction; D000072086:Smoothened Receptor; D014162:Transfection
D003598:Cytoskeletal Proteins; D053823:Hedgehog Proteins; D008565:Membrane Proteins; C484365:Pkhd1 protein, mouse; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D011985:Receptors, Serotonin; D017481:Receptors, Somatostatin; C465570:Shh protein, mouse; C491022:Smo protein, mouse; D000072086:Smoothened Receptor; C103631:somatostatin receptor 3; D019204:GTP-Binding Proteins; C106863:Sept2 protein, mouse; D058112:Septins