Mutation of CFAP57, a protein required for the asymmetric targeting of a subset of inner dynein arms in Chlamydomonas, causes primary ciliary dyskinesia.

TitleMutation of CFAP57, a protein required for the asymmetric targeting of a subset of inner dynein arms in Chlamydomonas, causes primary ciliary dyskinesia.
Publication TypeJournal Article
Year of Publication2020
AuthorsBustamante-Marin, XM, Horani, A, Stoyanova, M, Charng, W-L, Bottier, M, Sears, PR, Yin, W-N, Daniels, LAnne, Bowen, H, Conrad, DF, Knowles, MR, Ostrowski, LE, Zariwala, MA, Dutcher, SK
JournalPLoS Genet
Volume16
Issue8
Paginatione1008691
Date Published2020 08
ISSN1553-7404
Keywords3T3 Cells, Adult, Animals, Axoneme, Cells, Cultured, Chlamydomonas reinhardtii, Cilia, Ciliary Motility Disorders, Codon, Nonsense, Conserved Sequence, Dyneins, Humans, Male, Mice, Plant Proteins, Proteins, Respiratory Mucosa
Abstract

Primary ciliary dyskinesia (PCD) is characterized by chronic airway disease, reduced fertility, and randomization of the left/right body axis. It is caused by defects of motile cilia and sperm flagella. We screened a cohort of affected individuals that lack an obvious axonemal defect for pathogenic variants using whole exome capture, next generation sequencing, and bioinformatic analysis assuming an autosomal recessive trait. We identified one subject with an apparently homozygous nonsense variant [(c.1762C>T), p.(Arg588*)] in the uncharacterized CFAP57 gene. Interestingly, the variant results in the skipping of exon 11 (58 amino acids), which may be due to disruption of an exonic splicing enhancer. In normal human nasal epithelial cells, CFAP57 localizes throughout the ciliary axoneme. Nasal cells from the PCD patient express a shorter, mutant version of CFAP57 and the protein is not incorporated into the axoneme. The missing 58 amino acids include portions of WD repeats that may be important for loading onto the intraflagellar transport (IFT) complexes for transport or docking onto the axoneme. A reduced beat frequency and an alteration in ciliary waveform was observed. Knockdown of CFAP57 in human tracheobronchial epithelial cells (hTECs) recapitulates these findings. Phylogenetic analysis showed that CFAP57 is highly conserved in organisms that assemble motile cilia. CFAP57 is allelic with the BOP2/IDA8/FAP57 gene identified previously in Chlamydomonas reinhardtii. Two independent, insertional fap57 Chlamydomonas mutant strains show reduced swimming velocity and altered waveforms. Tandem mass tag (TMT) mass spectroscopy shows that FAP57 is missing, and the "g" inner dyneins (DHC7 and DHC3) and the "d" inner dynein (DHC2) are reduced, but the FAP57 paralog FBB7 is increased. Together, our data identify a homozygous variant in CFAP57 that causes PCD that is likely due to a defect in the inner dynein arm assembly process.

DOI10.1371/journal.pgen.1008691
Alternate JournalPLoS Genet.
PubMed ID32764743
PubMed Central IDPMC7444499
Grant ListP51 OD011092 / OD / NIH HHS / United States
R01 HL128370 / HL / NHLBI NIH HHS / United States
U54 HL096458 / HL / NHLBI NIH HHS / United States
R01 HL071798 / HL / NHLBI NIH HHS / United States
R01 HL117836 / HL / NHLBI NIH HHS / United States
UL1 TR000083 / TR / NCATS NIH HHS / United States
R01 HD078641 / HD / NICHD NIH HHS / United States
R01 MH101810 / MH / NIMH NIH HHS / United States
UM1 HG006504 / HG / NHGRI NIH HHS / United States
U24 HG008956 / HG / NHGRI NIH HHS / United States