Cby1 promotes Ahi1 recruitment to a ring-shaped domain at the centriole-cilium interface and facilitates proper cilium formation and function.
Bottom Line: Defects in centrosome and cilium function are associated with phenotypically related syndromes called ciliopathies.Superresolution microscopy using both three-dimensional SIM and STED reveals that Cby1 localizes to an ∼250-nm ring at the distal end of the mature centriole, in close proximity to Ofd1 and Ahi1, a component of the transition zone between centriole and cilium.This suggests that Cby1 is required for efficient recruitment of Ahi1, providing a possible molecular mechanism for the ciliogenesis defect in Cby1(-/-) cells.
Affiliation: Department of Biology, Stanford School of Medicine, Stanford University, Stanford, CA 94305.Show MeSH
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Mentions: When visualized by 3D-SIM, all of the proteins appeared to be organized as rings of ∼250–300 nm, consistent with being in close apposition to the centriole microtubules, in both cell types (Figure 4, A–C). For this characterization we used MTECs, which, in contrast to MEFs, have hundreds of centrioles docked in the same orientation and plane at the apical surface, allowing for determination of the relative localization of the proteins along the longitudinal axis of the centriole. XZ-projections of 3D-SIM images of MTECs demonstrated that Cby1 is located at a similar position along the longitudinal axis as Ahi1 and Ofd1 (Figure 4, A and B). In contrast, Cep164 and Sdccag8 are located closer to the proximal end of the centriole than Cby1 (farther from the cilium; Figure 4, A and C). It was not possible to image Tmem237 under the 3D-SIM conditions.
Affiliation: Department of Biology, Stanford School of Medicine, Stanford University, Stanford, CA 94305.