RESUMO
By moving essential body fluids and molecules, motile cilia and flagella govern respiratory mucociliary clearance, laterality determination and the transport of gametes and cerebrospinal fluid. Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder frequently caused by non-assembly of dynein arm motors into cilia and flagella axonemes. Before their import into cilia and flagella, multi-subunit axonemal dynein arms are thought to be stabilized and pre-assembled in the cytoplasm through a DNAAF2-DNAAF4-HSP90 complex akin to the HSP90 co-chaperone R2TP complex. Here, we demonstrate that large genomic deletions as well as point mutations involving PIH1D3 are responsible for an X-linked form of PCD causing disruption of early axonemal dynein assembly. We propose that PIH1D3, a protein that emerges as a new player of the cytoplasmic pre-assembly pathway, is part of a complementary conserved R2TP-like HSP90 co-chaperone complex, the loss of which affects assembly of a subset of inner arm dyneins.
Assuntos
Proteínas Reguladoras de Apoptose/genética , Dineínas do Axonema/metabolismo , Genes Ligados ao Cromossomo X/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Síndrome de Kartagener/genética , Proteínas dos Microtúbulos/genética , Chaperonas Moleculares/genética , Adolescente , Adulto , Animais , Proteínas Reguladoras de Apoptose/metabolismo , Axonema/patologia , Criança , Pré-Escolar , Cílios/patologia , Cílios/ultraestrutura , Citoplasma/patologia , Modelos Animais de Doenças , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/patologia , Células HEK293 , Proteínas de Choque Térmico HSP90/metabolismo , Humanos , Recém-Nascido , Peptídeos e Proteínas de Sinalização Intracelular , Síndrome de Kartagener/patologia , Masculino , Microscopia Eletrônica de Transmissão , Linhagem , Filogenia , Mutação Puntual , Dobramento de Proteína , Alinhamento de Sequência , Deleção de Sequência , Motilidade dos Espermatozoides/genética , Sequenciamento do Exoma , Peixe-ZebraRESUMO
Primary ciliary dyskinesia (PCD) is a ciliopathy characterized by airway disease, infertility, and laterality defects, often caused by dual loss of the inner dynein arms (IDAs) and outer dynein arms (ODAs), which power cilia and flagella beating. Using whole-exome and candidate-gene Sanger resequencing in PCD-affected families afflicted with combined IDA and ODA defects, we found that 6/38 (16%) carried biallelic mutations in the conserved zinc-finger gene BLU (ZMYND10). ZMYND10 mutations conferred dynein-arm loss seen at the ultrastructural and immunofluorescence level and complete cilia immotility, except in hypomorphic p.Val16Gly (c.47T>G) homozygote individuals, whose cilia retained a stiff and slowed beat. In mice, Zmynd10 mRNA is restricted to regions containing motile cilia. In a Drosophila model of PCD, Zmynd10 is exclusively expressed in cells with motile cilia: chordotonal sensory neurons and sperm. In these cells, P-element-mediated gene silencing caused IDA and ODA defects, proprioception deficits, and sterility due to immotile sperm. Drosophila Zmynd10 with an equivalent c.47T>G (p.Val16Gly) missense change rescued mutant male sterility less than the wild-type did. Tagged Drosophila ZMYND10 is localized primarily to the cytoplasm, and human ZMYND10 interacts with LRRC6, another cytoplasmically localized protein altered in PCD. Using a fly model of PCD, we conclude that ZMYND10 is a cytoplasmic protein required for IDA and ODA assembly and that its variants cause ciliary dysmotility and PCD with laterality defects.
