Broad-minded links cell cycle-related kinase to cilia assembly and hedgehog signal transduction.
Recent findings indicate that mammalian Sonic hedgehog (Shh) signal transduction occurs within primary cilia, although the cell biological mechanisms underlying both Shh signaling and ciliogenesis have not been fully elucidated. We show that an uncharacterized TBC domain-containing protein, Broad-minded (Bromi), is required for high-level Shh responses in the mouse neural tube. We find that Bromi controls ciliary morphology and proper Gli2 localization within the cilium. By use of a zebrafish model, we further show that Bromi is required for proper association between the ciliary membrane and axoneme. Bromi physically interacts with cell cycle-related kinase (CCRK), whose Chlamydomonas homolog regulates flagellar length. Biochemical and genetic interaction data indicate that Bromi promotes CCRK stability and function. We propose that Bromi and CCRK control the structure of the primary cilium by coordinating assembly of the axoneme and ciliary membrane, allowing Gli proteins to be properly activated in response to Shh signaling.
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Hyuk Wan
HW
Ko
Ryan X
RX
Norman
John
J
Tran
Kimberly P
KP
Fuller
Mitsunori
M
Fukuda
Jonathan T
JT
Eggenschwiler
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D002923:Cilia / Q000502:physiology* / Q000648:ultrastructure; D003001:Cloning, Molecular; D018844:Cyclin-Dependent Kinases / Q000502:physiology*; D004247:DNA / Q000235:genetics; D004795:Enzyme Stability; D004843:Epistasis, Genetic; D005260:Female; D053823:Hedgehog Proteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D009154:Mutation; D054259:Neural Tube / Q000196:embryology; D011247:Pregnancy; D015398:Signal Transduction; D015027:Zebrafish / Q000196:embryology / Q000235:genetics; D029961:Zebrafish Proteins / Q000235:genetics / Q000502:physiology; D000095043:Cyclin-Dependent Kinase-Activating Kinase
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D053823:Hedgehog Proteins; C548167:Tbc1d32 protein, mouse; D029961:Zebrafish Proteins; D004247:DNA; D018844:Cyclin-Dependent Kinases; D000095043:Cyclin-Dependent Kinase-Activating Kinase