CCDC151 Mutations Cause Primary Ciliary Dyskinesia by Disruption of the Outer Dynein Arm Docking Complex Formation

Abstract

A diverse family of cytoskeletal dynein motors powers various cellular transport systems, including axonemal dyneins generating the force for ciliary and flagellar beating essential to movement of extracellular fluids and of cells through fluid. Multisubunit outer dynein arm (ODA) motor complexes, produced and preassembled in the cytosol, are transported to the ciliary or flagellar compartment and anchored into the axonemal microtubular scaffold via the ODA docking complex (ODA-DC) system. In humans, defects in ODA assembly are the major cause of primary ciliary dyskinesia (PCD), an inherited disorder of ciliary and flagellar dysmotility characterized by chronic upper and lower respiratory infections and defects in laterality. Here, by combined high-throughput mapping and sequencing, we identified CCDC151 loss-of-function mutations in five affected individuals from three independent families whose cilia showed a complete loss of ODAs and severely impaired ciliary beating. Consistent with the laterality defects observed in these individuals, we found Ccdc151 expressed in vertebrate left-right organizers. Homozygous zebrafish ccdc151(ts272a) and mouse Ccdc151(Snbl) mutants display a spectrum of situs defects associated with complex heart defects. We demonstrate that CCDC151 encodes an axonemal coiled coil protein, mutations in which abolish assembly of CCDC151 into respiratory cilia and cause a failure in axonemal assembly of the ODA component DNAH5 and the ODA-DC-associated components CCDC114 and ARMC4. CCDC151-deficient zebrafish, planaria, and mice also display ciliary dysmotility accompanied by ODA loss. Furthermore, CCDC151 coimmunoprecipitates CCDC114 and thus appears to be a highly evolutionarily conserved ODA-DC-related protein involved in mediating assembly of both ODAs and their axonemal docking machinery onto ciliary microtubules.

DNAH11 Localization in the Proximal Region of Respiratory Cilia Defines Distinct Outer Dynein Arm Complexes

“…We also observed normal proximal DNAH11 localization in these DNAAF1-and DNAAF3-mutant cilia ( Figures 6D and 6E), demonstrating that the integrity of neither the ODA nor IDA macromolecular complex is essential for DNAH11 assembly in respiratory axonemes. Further supporting this observation, we also determined that DNAH11 retains proximal ciliary localization in CCDC151-mutant respiratory cilia, which also have ODA defects, due to functional loss of the ODA axonemal docking complex (27) (see Figure E11).…”

Direction of flagellum beat propagation is controlled by proximal/distal outer dynein arm asymmetry

“…Given that mutations both in docking complexes (61) and in proteins with an asymmetric localisation(36) lead to primary ciliary dyskinesia in humans, a better understanding of the mechanisms by which asymmetry occurs and how it contributes to flagellar motility is essential. Here, we demonstrate that molecular asymmetries within the axoneme can be generated by an IFTdependent concentration gradient of proteins within the flagellum and that this asymmetry is linked to the control of waveform initiation, defining whether a tip-to-base or base-to-tip beat occurs.…”

c21orf59/kurly Controls Both Cilia Motility and Polarization

“…The zebrafish and Xenopus model systems have been used to understand the components and mechanisms required for cilia-generated fluid flow (Becker-Heck et al, 2011; Hjeij et al, 2014; Kishimoto et al, 2008; Mitchell et al, 2007; Panizzi et al, 2012; Tarkar et al, 2013; Zhao et al, 2013). Here, we describe two zebrafish mutants, called kurly ( kur ) that disrupt c21orf59 , a gene recently implicated in human PCD (Austin-Tse et al, 2013).…”