BAR Domain-Containing FAM92 Proteins Interact with Chibby1 To Facilitate Ciliogenesis

Abstract

Chibby1 (Cby1) is a small, conserved coiled-coil protein that localizes to centrioles/basal bodies and plays a crucial role in the formation and function of cilia. During early stages of ciliogenesis, Cby1 is required for the efficient recruitment of small vesicles at the distal end of centrioles to facilitate basal body docking to the plasma membrane. Here, we identified family with sequence similarity 92, member A (FAM92A) and FAM92B, which harbor predicted lipid-binding BAR domains, as novel Cby1-interacting partners using tandem affinity purification and mass spectrometry. We found that in cultured cell lines, FAM92A colocalizes with Cby1 at the centrioles/basal bodies of primary cilia, while FAM92B is undetectable. In airway multiciliated cells, both FAM92A and -92B colocalize with Cby1 at the base of cilia. Notably, the centriolar localization of FAM92A and -92B depends largely on Cby1. Knockdown of FAM92A in RPE1 cells impairs ciliogenesis. Consistent with the membrane-remodeling properties of BAR domains, FAM92A and -92B in cooperation with Cby1 induce deformed membrane-like structures containing the small GTPase Rab8 in cultured cells. Our results therefore suggest that FAM92 proteins interact with Cby1 to promote ciliogenesis via regulation of membrane-remodeling processes.

Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.00160-16.

ACKNOWLEDGMENTS

We thank Erich Nigg and Gislene Pereira for the CEP164 antibodies, Kazuhisa Nakayama and Hye-Won Shin for the HA-tagged arfaptin-1 and arfaptin-2 expression constructs, Miguel Garcia-Diaz for help with 3D structural modeling of FAM92 BAR domains using the Phyre2 server, and Antonius Kohler at the Stony Brook Proteomics Center for help with mass spectrometry.

This work was supported by an NSF grant (MCB1140033) to R.K. and an NIH-NHLBI grant (R01HL107493) to K.-I.T. S.S.S. was supported by Stony Brook Medical Scientist Training Program grant T32 GM008444-23. The purchase of the Nikon SIM instrument was supported in part by an NIH Shared Instrumentation grant (S10OD016405-01).