Microtubules are ubiquitous eukaryotic structures, built of dimers of 1- and 2-tubulin. Microtubules play key roles in cell motility, intracellular trafficking and cell polarization. It is not well understood how diverse microtubules function in multiple contexts inside the cell. Commonly, motor proteins move specific cellular cargoes along subsets of microtubules, and this selective transport is critical for cell polarization. One striking example is the neuron, where specific cargoes are moved from the cell body either into the dendrite or axon projections. The principles and mechanisms that govern the selective transport on the surface of microtubules are not well understood. We explore a hypothesis that microtubules are functionally adapted for selective transport and other localized functions, by spatially restricted post-translational modifications (PTMs) of tubulin subunits. Acetylation of K40 on 1- tubulin is a highly conserved PTM, that marks microtubules which turnover relatively slowly. In neurons, K40 acetylation of 1-tubulin is highly enriched on microtubules of the axon as compared to microtubules in dendrites. Recent studies indicate that K40 acetylation of axonal microtubules stimulates binding and motility of specific motor proteins, including kinesin-1 inside the axon. We report here an identification of a conserved protein that is required for K40 1-tubulin acetylation in the model protist Tetrahymena and zebrafish. This protein is an ortholog of MEC-17, a previously studied protein which is required for the function of touch receptor neurons in C. elegans. We show that MEC-17 mediates acetylation of K40 on 1- tubulin in vitro. We will test the hypothesis that MEC17 is the long-sought 1-tubulin K40 acetyltransferase, and that MEC-17, by acetylating K40 on 1-tubulin, contributes to neuronal differentiation and function. We will use model organisms, the worm Caenorhabditis elegans and zebrafish Danio rerio, to evaluate the function of MEC-17 and K40 acetylation on 1- tubulin, specifically in two types of neurons: in touch receptor neurons (C. elegans) and in primary motor neurons (zebrafish). As acetylation of 1-tubulin is highly enriched in the nervous system, this proposal is relevant to a broad range of diseases and in particular to the neurodegenerative disorders.

Public Health Relevance

Eukaryotic cells are filled with fibers known as microtubules, that serve as tracks for intracellular transport and regulate the shape of cells. This project will test a hypothesis that patterns of biochemical marks on the surface of microtubules adapt specific microtubule fibers for specific functions, including a selective transport of certain cellular components. This project will have an impact on understanding of pathology of human diseases that are associated with defects in microtubules, including some neurodegenerative disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM089912-03
Application #
8257521
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Gindhart, Joseph G
Project Start
2010-05-01
Project End
2014-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
3
Fiscal Year
2012
Total Cost
$286,679
Indirect Cost
$93,629
Name
University of Georgia
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
004315578
City
Athens
State
GA
Country
United States
Zip Code
30602
Louka, Panagiota; Vasudevan, Krishna Kumar; Guha, Mayukh et al. (2018) Proteins that control the geometry of microtubules at the ends of cilia. J Cell Biol 217:4298-4313
Kushida, Yasuharu; Takaine, Masak; Nakano, Kentaro et al. (2017) Kinesin-14 is Important for Chromosome Segregation During Mitosis and Meiosis in the Ciliate Tetrahymena thermophila. J Eukaryot Microbiol 64:293-307
Bayless, Brian A; Galati, Domenico F; Junker, Anthony D et al. (2016) Asymmetrically localized proteins stabilize basal bodies against ciliary beating forces. J Cell Biol 215:457-466
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
Urbanska, Paulina; Song, Kangkang; Joachimiak, Ewa et al. (2015) The CSC proteins FAP61 and FAP251 build the basal substructures of radial spoke 3 in cilia. Mol Biol Cell 26:1463-75
Bregier, Cezary; Krzemien-Ojak, Lucja; Wloga, Dorota et al. (2013) PHLP2 is essential and plays a role in ciliogenesis and microtubule assembly in Tetrahymena thermophila. J Cell Physiol 228:2175-89
Shiozaki, Nanami; Nakano, Kentaro; Kushida, Yasuharu et al. (2013) ADF/cofilin is not essential but is critically important for actin activities during phagocytosis in Tetrahymena thermophila. Eukaryot Cell 12:1080-6
Gaertig, Jacek; Wloga, Dorota; Vasudevan, Krishna Kumar et al. (2013) Discovery and functional evaluation of ciliary proteins in Tetrahymena thermophila. Methods Enzymol 525:265-84
Berbari, Nicolas F; Sharma, Neeraj; Malarkey, Erik B et al. (2013) Microtubule modifications and stability are altered by cilia perturbation and in cystic kidney disease. Cytoskeleton (Hoboken) 70:24-31

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