We will investigate the early steps of basal body assembly by utilizing the cytology and molecular genetic advantages of the ciliate, Tetrahymena thermophila. Basal bodies have the defining structural characteristic of a conserved radial array of nine microtubule structures and serve to nucleate cilia and flagella. Dysfunction in basal body or ciliary components results in pleiotropic human diseases, collectively known as ciliopathies. Ciliopathies affect several organ systems and developmental processes, reflecting the importance of basal bodies and cilia to a wide range of cell types. Furthermore, most cell types interconvert basal bodies and centrioles, the latter of which function in organizing centrosomes. Many tumor cells have aberrant centriole structure and number, which contributes to genetic instability during cell division. Despite the importance of basal bodies and centrioles, our understanding of their molecular composition, architecture, and assembly remains sparse. Basal body assembly has been monitored by electron microscopy, revealing that the site of nascent basal body assembly is associated with an amorphous accumulation of proteins from which the cartwheel, the first recognizable structural intermediate of the basal body, is formed. In the first aim, we will study the role of centrins and their binding partners, Sfi1-repeat proteins, at the site of nascent basal body assembly. We will determine which centrin/Sfi1-repeat complex(es) is at this site and investigate the importance of the interaction between centrin and its cognate Sfi1-repeat protein during basal body assembly.
The second aim focuses on the cartwheel structure, which consists of a circular hub and nine spokes that nucleate the first of the triplet microtubules. We have shown that the conserved proteins Sas6a and Sas6b localize to the hub of the cartwheel and required for its assembly. We have identified candidate cartwheel proteins in complex with Sas6a. We will verify whether these proteins are cartwheel components, establishing whether they function in cartwheel assembly, and determine if they bind Sas6a directly. Furthermore, we will establish whether vertebrate orthologs of the new cartwheel proteins are found in vertebrate basal bodies or centrioles and function in these structures. Finally, we have demonstrated that many basal body components have both a stably incorporated population and a dynamically exchanging population. In the third aim, we propose to explore the in vivo and in vitro requirements for the dynamic exchange of cartwheel components, starting with Sas6a, to determine the mechanisms of exchange in basal body function. We will also ask whether mechanisms of dynamic exchange are shared with those for stable incorporation during basal body assembly, answering the question of whether a component has a single or multiple mechanisms of incorporation into a basal body. The proposed research program will elucidate key components and mechanisms for the early stages of basal body and centriole assembly, and for exchange of proteins that may contribute to maintaining the integrity of these structures.

Public Health Relevance

The aim of this work is to understand processes regulating the assembly and function of the basal body. The basal body forms the cilium found on most cells in the human body and as such, is involved in a number of developmental and cellular processes. Defects in cilia formation can lead to a variety human diseases including mental retardation, kidney failure, obesity and loss of vision. In order to understand the symptoms caused by these diseases, a complete understanding of the components required to build and maintain basal bodies and cilia is essential.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
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Deatherage, James F
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University of Colorado at Boulder
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Meehl, Janet B; Bayless, Brian A; Giddings Jr, Thomas H et al. (2016) Tetrahymena Poc1 ensures proper intertriplet microtubule linkages to maintain basal body integrity. Mol Biol Cell 27:2394-403
Zhao, Ying; Shi, Jianli; Winey, Mark et al. (2016) Identifying domains of EFHC1 involved in ciliary localization, ciliogenesis, and the regulation of Wnt signaling. Dev Biol 411:257-265
Shi, Jianli; Zhao, Ying; Vonderfecht, Tyson et al. (2015) Centrin-2 (Cetn2) mediated regulation of FGF/FGFR gene expression in Xenopus. Sci Rep 5:10283
Cole, Eric S; Giddings Jr, Thomas H; Ozzello, Courtney et al. (2015) Membrane dynamics at the nuclear exchange junction during early mating (one to four hours) in the ciliate Tetrahymena thermophila. Eukaryot Cell 14:116-27
Square, Tyler; Romášek, Marek; Jandzik, David et al. (2015) CRISPR/Cas9-mediated mutagenesis in the sea lamprey Petromyzon marinus: a powerful tool for understanding ancestral gene functions in vertebrates. Development 142:4180-7
Winey, Mark; O'Toole, Eileen (2014) Centriole structure. Philos Trans R Soc Lond B Biol Sci 369:
Winey, Mark; Meehl, Janet B; O'Toole, Eileen T et al. (2014) Conventional transmission electron microscopy. Mol Biol Cell 25:319-23
Shi, Jianli; Zhao, Ying; Galati, Domenico et al. (2014) Chibby functions in Xenopus ciliary assembly, embryonic development, and the regulation of gene expression. Dev Biol 395:287-98
Stemm-Wolf, Alexander J; Meehl, Janet B; Winey, Mark (2013) Sfr13, a member of a large family of asymmetrically localized Sfi1-repeat proteins, is important for basal body separation and stability in Tetrahymena thermophila. J Cell Sci 126:1659-71
Ross, Ian; Clarissa, Christina; Giddings Jr, Thomas H et al. (2013) ?-tubulin is essential in Tetrahymena thermophila for the assembly and stability of basal bodies. J Cell Sci 126:3441-51

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