Fig. 2: Ccdc57 is an FGM component located at the BB distal end as a punctum in mEPCs.

a, b Localization of Ccdc57 in mEPCs undergoing massive BB biogenesis. Cultured mEPC precursors from P0 mouse brain tissues were induced to differentiate into multiciliated cells through serum starvation as illustrated (a)²³. The cells were immunostained and imaged through 3D-SIM (b). Illustrations (side views) (b) are provided to aid comprehension of the localizations of Cep152 (blue), Centrin (red), and Odf2 (gray). Dashed circles mark outlines of nuclear envelope-associated Ccdc57 puncta. Representative nascent BBs (transverse images) were magnified 4-fold and are shown as 4-channel-merged images. Note that nascent BBs in stage II are negative for Odf2²³. c Ccdc57 localized at BB distal end as a punctum. Colored arrows point to the BB-localized proteins. Models are provided to aid comprehension. The dashed line marks the middle position of the Odf2-ring. Refer to Supplementary Fig. 1a for the cell image from which the representative BBs were cropped and also for additional examples. d–f GFP-Ccdc57 recapitulated the FGM and BB localizations of endogenous Ccdc57. mEPCs infected with adenovirus to expressed GFP-Ccdc57 (d) were immunostained to visualize Odf2 (e, f). DAPI, a DNA-specific dye, was used to label the nucleus (e). BBs pointed by the white arrow (e) were magnified 4-fold to show details. Refer to Supplementary Fig. 1b for an additional mEPC and Supplementary Fig. 1c for the cell image from which the representative BBs (f) were cropped and also for additional BB examples. At least three biologically independent experiments were performed (b, c, e, f). Source data are provided as a Source Data file.