Primary ciliary dyskinesia (PCD) is characterized by dysfunction of respiratory cilia and sperm flagella and random determination of visceral asymmetry. Here, we identify the DRC1 subunit of the nexin-dynein regulatory complex (N-DRC), an axonemal structure critical for the regulation of dynein motors, and show that mutations in the gene encoding DRC1, CCDC164, are involved in PCD pathogenesis. Loss-of-function mutations disrupting DRC1 result in severe defects in assembly of the N-DRC structure and defective ciliary movement in Chlamydomonas reinhardtii and humans. Our results highlight a role for N-DRC integrity in regulating ciliary beating and provide the first direct evidence that mutations in DRC genes cause human disease.
Bibliographical noteFunding Information:
We thank G. Piperno for providing the peptide sequences used to identify the Chlamydomonas DRC1 gene. M.E.P. also thanks C. Perrone, T. vy Le, A. Bostrom, J. Mueller and J.A. Knott for assistance with mapping the DRC1 locus, P. Kathir, C. Silflow and S. Dutcher for advice on RFLP mapping and T. Markowski and B. Witthun for assistance with mass spectrometry and spectral counting. We thank the German patient support group Kartagener Syndrom und Primaere Ciliaere Dyskinesie e.V. We also thank A. Heer and C. Westermann for excellent technical assistance. We thank M. Laudon and the Chlamydomonas Genetics Center for strains. For antibodies, we thank R. Linck (University of Minnesota) for antibody to Rib72, M. Sanders (University of Minnesota) for MC1 antibody to centrin, R. Kamiya (University of Tokyo) for antibodies to tektin, p44 and p38, T. Yagi (Kyoto University) for antibodies to DHC5, DHC9 and DHC11, P. Yang (Marquette University) for antibody to RSP16, E. Smith (Dartmouth College) for antibody to CaMIP3 and G. Piperno (Mount Sinai School of Medicine) for antibody to p28). This work was supported by US National Institutes of Health (NIH) grants to M.E.P. (GM55667) and W.S.S. (GM051173), a National Research Service Award (NRSA) postdoctoral fellowship to M.W. (GM075446), funding to W.S.S. from the Children’s Healthcare of Atlanta and Emory University School of Medicine Pediatric Research Center and funding to H. Omran (Deutsche Forschungsgemeinschaft DFG Om 6/4 and Om 6/5, GRK1104, SFB592, IZKF Muenster and the Cell Dynamics and Disease (CEDAD) graduate school as well as SYSCILIA from the European Community). The Center for Mass Spectrometry and Proteomics at the University of Minnesota is supported by multiple grants, including National Science Foundation (NSF) Major Research Instrumentation grants 9871237 and NSFDBI0215759. Technical and software support was also provided by the Minnesota Supercomputing Institute.