Mutations in C11orf70 Cause Primary Ciliary Dyskinesia with Randomization of Left/Right Body Asymmetry Due to Defects of Outer and Inner Dynein Arms

AbstractPrimary ciliary dyskinesia (PCD) is characterized by chronic airway disease, male infertility and randomization of the left/right body axis caused by defects of motile cilia and sperm flagella. We identified loss-of-function mutations in the open reading frame C11ORF70 in PCD individuals from five distinct families. Transmission electron microscopy analyses and high resolution immunofluorescence microscopy demonstrate that loss-of-function mutations in C11ORF70 cause immotility of respiratory cilia and sperm flagella, respectively, due to loss of axonemal outer (ODAs) and inner dynein arms (IDAs), indicating that C11ORF70 is involved in cytoplasmic assembly of dynein arms. Expression analyses of C11ORF70 showed that C11ORF70 is expressed in ciliated respiratory cells and that the expression of C11ORF70 is upregulated during ciliogenesis, similar to other previously described cytoplasmic dynein arm assembly factors. Furthermore, C11ORF70 shows an interaction with cytoplasmic ODA/IDA assembly factor DNAAF2, supporting our hypothesis that C11ORF70 is a novel preassembly factor involved in the pathogenesis of PCD. The identification of a novel genetic defect that causes PCD and male infertility is of great clinical importance as well as for genetic counselling.

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C11orf70 mutations causing primary ciliary dyskinesia disrupt a conserved step in the intraflagellar transport-dependent assembly of multiple axonemal dyneins

10.1101/211953 ◽

2017 ◽

Author(s):

Mahmoud R. Fassad ◽

Amelia Shoemark ◽

Pierrick le Borgne ◽

France Koll ◽

Mitali Patel ◽

...

Keyword(s):

Primary Ciliary Dyskinesia ◽

Intraflagellar Transport ◽

Similar Distribution ◽

Targeted Next Generation Sequencing ◽

Respiratory Cilia ◽

Dynein Arms ◽

Active Transport Process ◽

Cytoplasmic Assembly ◽

Ciliary Dyskinesia ◽

Generation Sequencing

AbstractPrimary ciliary dyskinesia (PCD) is a genetically and phenotypically heterogeneous disorder characterized by destructive respiratory disease and laterality abnormalities due to randomised left-right body asymmetry. PCD is mostly caused by mutations affecting components of the core axoneme structure of motile cilia that are essential for cilia movement. In addition, there is a growing group of PCD genes that encode proteins essential for the assembly of the ciliary dynein motors and the active transport process that delivers them from their cytoplasmic assembly site into the axoneme. We screened a cohort of affected individuals for disease-causing mutations using a targeted next generation sequencing panel and identified 2 unrelated families (3 affected children) with mutations in the uncharacterized C11orf70 gene. The affected children share a consistent PCD phenotype from early life with laterality defects and immotile respiratory cilia displaying combined loss of inner and outer dynein arms (IDA+ODA). Phylogenetic analysis shows C11orf70 is highly conserved, distributed across species similarly to proteins involved in the intraflagellar transport (IFT)-dependant assembly of axonemal dyneins. Paramecium C11orf70 RNAi knockdown led to combined loss of ciliary IDA+ODA with reduced cilia beating and swim velocity. Fluorescently tagged C11orf70 in Paramecium and Chlamydomonas localises mainly in the cytoplasm with a small amount in the ciliary component, its abundance in the axoneme being IFT-dependant. During ciliogenesis, C11orf70 accumulates at the ciliary tips in a similar distribution to the IFT-B protein IFT46. In summary, C11orf70 is essential for IFT-dependant assembly of dynein arms and C11orf70 mutations cause defective cilia motility and PCD.

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The Drosophila orthologue of the primary ciliary dyskinesia-associated gene, DNAAF3, is required for axonemal dynein assembly

10.1101/2021.05.11.443597 ◽

2021 ◽

Author(s):

Petra zur Lage ◽

Zhiyan Xi ◽

Jennifer Lennon ◽

Iain Hunter ◽

Wai Kit Chan ◽

...

Keyword(s):

Primary Ciliary Dyskinesia ◽

Cell Types ◽

Drosophila Cell ◽

Heavy Chains ◽

Neuron Response ◽

Dynein Motor ◽

Assembly Factor ◽

Axonemal Dynein ◽

Dynein Arms ◽

Ciliary Dyskinesia

Ciliary motility is powered by a suite of highly conserved axoneme-specific dynein motor complexes. In humans the impairment of these motors through mutation results in the disease, Primary Ciliary Dyskinesia (PCD). Studies in Drosophila have helped to validate several PCD genes whose products are required for cytoplasmic pre-assembly of axonemal dynein motors. Here we report the characterisation of the Drosophila homologue of the less known assembly factor, DNAAF3. This gene, CG17669 (Dnaaf3), is expressed exclusively in developing mechanosensory chordotonal (Ch) neurons and spermatocytes, the only two Drosophila cell types bearing motile cilia/flagella. Mutation of Dnaaf3 results in larvae that are deaf and adults that are uncoordinated, indicating defective Ch neuron function. The mutant Ch neuron cilia of the antenna specifically lack dynein arms, while Ca imaging in larvae reveals a complete loss of Ch neuron response to vibration stimulus, confirming that mechanotransduction relies on ciliary dynein motors. Mutant males are infertile with immotile sperm whose flagella lack dynein arms and show axoneme disruption. Analysis of proteomic changes suggest a reduction in heavy chains of all axonemal dynein forms, consistent with an impairment of dynein pre-assembly.

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