The goal of this project is to understand how microtubule networks are regulated by molecular diversity at the level of tubulin proteins. Tubulin proteins assemble into dynamic microtubule polymers that form networks with associated motor proteins to organize the cell in diverse contexts. Defects in microtubule function are linked to numerous human diseases, including neuropathies and cancer. Understanding the mechanisms that regulate microtubule networks is therefore critical for understanding how defects contribute to the disease state. A major deficit in our understanding is how molecular diversity at the level of tubulin proteins -- mutations, isotype expression, posttranslational modifications -- lead to changes at the level of the network. My laboratory is now poised to address this deficit by overcoming two historical barriers in the microtubule field. First, we have developed a genetic model for manipulating tubulin proteins by directed mutation. Second, we extend our genetic model to complementary systems for analyzing how CTTs affect tubulin biochemistry, MT motor activity, and MT function in vivo. By applying these synergistic approaches, we can distinguish effects on intrinsic microtubule dynamics from effects on motors and other extrinsic regulators, and we can determine the consequences of these effects for a cellular network. In this project, we will determine the roles of carboxy-terminal tail motifs (CTTs) of ?- and ? tubulin. CTTs support electrostatic interactions with motors and other proteins at the MT surface, exhibit sequence diversity across tissue-specific tubulin isotypes, and are major sites of post-translational modification. We hypothesize that CTTs regulate network behavior by promoting microtubule dynamics and the activity of evolutionarily distinct classes of MT motors. We will test this hypothesis in three aims: 1) Determine how CTTs directly affect the assembly of tubulin proteins into microtubule polymers. 2) Determine how CTTs regulate evolutionarily conserved kinesin motors. 3) Define the molecular roles of CTTs in the assembly of a complex cellular microtubule network - the mitotic spindle. The results of this work will provide new insight into the molecular regulation of microtubule networks. Furthermore, these studies will set the stage for future investigations of the roles of tubulin posttranslational modifications, isotyp expression, and disease-associated alleles.

Public Health Relevance

The microtubule network plays a critical role in organizing cells. Although defects in microtubule function are associated with numerous human diseases, including neuropathies and cancer, we do not understand how molecular diversity at the level of tubulin proteins contributes to altered microtubule function and pathology. This project uses novel approaches to determine how carboxy-terminal tail motifs within tubulin proteins regulate microtubule function and tune network behavior.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM112893-02
Application #
9116880
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Gindhart, Joseph G
Project Start
2015-08-01
Project End
2020-07-31
Budget Start
2016-08-01
Budget End
2017-07-31
Support Year
2
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Colorado Denver
Department
Biology
Type
Schools of Medicine
DUNS #
041096314
City
Aurora
State
CO
Country
United States
Zip Code
80045
Fees, Colby P; Moore, Jeffrey K (2018) Regulation of microtubule dynamic instability by the carboxy-terminal tail of ?-tubulin. Life Sci Alliance 1:
Fees, Colby P; Estrem, Cassi; Moore, Jeffrey K (2017) High-resolution Imaging and Analysis of Individual Astral Microtubule Dynamics in Budding Yeast. J Vis Exp :
Aiken, Jayne; Buscaglia, Georgia; Bates, Emily A et al. (2017) The ?-Tubulin gene TUBA1A in Brain Development: A Key Ingredient in the Neuronal Isotype Blend. J Dev Biol 5:
Estrem, Cassi; Fees, Colby P; Moore, Jeffrey K (2017) Dynein is regulated by the stability of its microtubule track. J Cell Biol 216:2047-2058
Gartz Hanson, M; Aiken, Jayne; Sietsema, Daniel V et al. (2016) Novel ?-tubulin mutation disrupts neural development and tubulin proteostasis. Dev Biol 409:406-19
Fees, Colby P; Aiken, Jayne; O'Toole, Eileen T et al. (2016) The negatively charged carboxy-terminal tail of ?-tubulin promotes proper chromosome segregation. Mol Biol Cell 27:1786-96
Mangan, Anthony J; Sietsema, Daniel V; Li, Dongying et al. (2016) Cingulin and actin mediate midbody-dependent apical lumen formation during polarization of epithelial cells. Nat Commun 7:12426
Nithianantham, Stanley; Le, Sinh; Seto, Elbert et al. (2015) Tubulin cofactors and Arl2 are cage-like chaperones that regulate the soluble ??-tubulin pool for microtubule dynamics. Elife 4: