The overall goal of our work is to understand the assembly and regulation of motile cilia. Cilia play vital motile and signaling roles in virtually every differentiated cell. As a consequence, failure in conserved assembly mechanisms, including the transport machine IFT (intraflagellar transport) and assembly of dynein motors, results in a wide range of human diseases including primary cilia dyskinesia (PCD) and consequences for development and adult organ function. Although we have a good understanding of ciliary structure and dynein motor organization, we are only beginning to understand how the dynein motor complexes are transported and assembled. Gaps in knowledge include steps and factors required for cytoplasmic ?preassembly? of axonemal dyneins, transport into the ciliary compartment, loading of complexes on IFT and regulation of transport, regulation of cargo-IFT unloading and targeting and docking of complexes on outer doublet microtubules in a 96nm repeat organization. The current focus of our work is on assembly of the ciliary axonemal inner dynein arm called I1 dynein, also known as dynein f, as an ideal model for axonemal dynein transport and assembly in the axoneme. I1 dynein is a large, conserved, two-headed inner dynein arm that is required for normal ciliary movement and regulation of axonemal bending. I1 dynein is a ?slow?, possibly non-canonical, axonemal dynein thought to resist microtubule sliding driven by other ?fast? axonemal dyneins. As such, I1 dynein, plays a critical role in control of axonemal bending and waveform. We have also determined that I1 dynein is preassembled in the cytoplasm, transported by IFT and targeted to a unique position repeating every 96 nm along each of the doublet microtubule, and assembles independent of the assembly of the other dyneins. Here we will address the transport of I1 dynein, as a cargo for IFT, and test the hypothesis that the Chlamydomonas IDA3 gene, which encodes a coiled-coil protein, Ida3, is specifically required for IFT transport of I1 dynein (Aim 1). We also test the hypothesis that the intermediate chain IC140 interacts with a docking protein or proteins for localization of I1 on the doublet microtubule (Aim 2). From this new work, we will learn how dyneins, as cargoes, are transported to and within cilia, and address the principle that each axonemal complex (e.g. dyneins, radial spokes, N-DRC) require specialized adaptors or regulators for directed transport. In addition, we will, for the first time, learn how an axonemal inner dynein arm is localized in the 96 nm repeat.

Public Health Relevance

Defects in motile cilia lead to ?Ciliopathies??multiple pathologies that affect the developing embryo and adult human. Our studies will identify conserved genes, that when defective, may result in Primary Cilia Dyskinesia, and consequent problems in embryonic development, fertility and respiratory disease in humans.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Ainsztein, Alexandra M
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Emory University
Anatomy/Cell Biology
Schools of Medicine
United States
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King, Stephen M; Sale, Winfield S (2018) Fifty years of microtubule sliding in cilia. Mol Biol Cell 29:698-701
Hunter, Emily L; Lechtreck, Karl; Fu, Gang et al. (2018) The IDA3 adapter, required for intraflagellar transport of I1 dynein, is regulated by ciliary length. Mol Biol Cell 29:886-896
Yamamoto, Ryosuke; Obbineni, Jagan M; Alford, Lea M et al. (2017) Chlamydomonas DYX1C1/PF23 is essential for axonemal assembly and proper morphology of inner dynein arms. PLoS Genet 13:e1006996
Alford, Lea M; Stoddard, Daniel; Li, Jennifer H et al. (2016) The nexin link and B-tubule glutamylation maintain the alignment of outer doublets in the ciliary axoneme. Cytoskeleton (Hoboken) 73:331-40
Vasudevan, Krishna Kumar; Song, Kangkang; Alford, Lea M et al. (2015) FAP206 is a microtubule-docking adapter for ciliary radial spoke 2 and dynein c. Mol Biol Cell 26:696-710
Vasudevan, Krishna Kumar; Jiang, Yu-Yang; Lechtreck, Karl F et al. (2015) Kinesin-13 regulates the quantity and quality of tubulin inside cilia. Mol Biol Cell 26:478-94
Yang, Fan; Pavlik, Jacqueline; Fox, Laura et al. (2015) Alcohol-induced ciliary dysfunction targets the outer dynein arm. Am J Physiol Lung Cell Mol Physiol 308:L569-76
Avasthi, Prachee; Onishi, Masayuki; Karpiak, Joel et al. (2014) Actin is required for IFT regulation in Chlamydomonas reinhardtii. Curr Biol 24:2025-32
Viswanadha, Rasagnya; Hunter, Emily L; Yamamoto, Ryosuke et al. (2014) The ciliary inner dynein arm, I1 dynein, is assembled in the cytoplasm and transported by IFT before axonemal docking. Cytoskeleton (Hoboken) 71:573-86
Alford, Lea M; Mattheyses, Alexa L; Hunter, Emily L et al. (2013) The Chlamydomonas mutant pf27 reveals novel features of ciliary radial spoke assembly. Cytoskeleton (Hoboken) 70:804-18

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