Microtubules (MTs) are rigid polymers that serve a critical role in cellular architecture as structural buttresses and tracks for motor proteins. In this capacity MTs are central to cellular processes ranging from mitotic chromosome segregation to changes in cellular morphology and vesicle transport. MTs are also important targets for anticancer drugs such as the vinca alkaloids and taxol. MTs are inherently dynamic, and their polymerization is regulated by cells to achieve rapid restructuring of the cytoskeleton. The molecular mechanisms of MT polymerization dynamics are not well understood, and this confounds rigorous understanding how MTs are structured and regulated by cells, as well as the mechanism of action of chemotherapy agents. This proposal characterizes the molecular events during microtubule polymerization. By combining optical tweezers with a novel system of photolithographically produced barriers, the events at the tip of a dynamic MT are tracked with nanometer precision. This reveals critical details of polymerization that have not been previously observed due to the light resolution limit. This assay will be applied to characterize molecular events that mediate microtubule growth, shortening, and stability. Additional studies will examine the molecular kinetics underlying modulation of microtubule dynamics by taxol and the microtubule associated protein tau. To build a mechanistic understanding of microtubule dynamics/these results will be interpreted in the context of physical models that describe the interplay between the evolving structure at a microtubule tip and the kinetics of subunit addition and loss. Relevance: This work will provide an understanding of cellular mechanics fundamental to the sustenance of life. By describing the fundamental mechanics of MT dynamics this work will increase our understanding of disease processes that involve MTs, such as mitotic failures (e.g. in aging and genetic diseases such as Down's syndrome), and neurodegenerative disease. Specifically addressed are the mechanisms of the important chemotherapy agent taxol, and the MT binding protein tau which plays a central role in a variety of neurodegenerative diseases. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM076177-01A2
Application #
7259066
Study Section
Cell Structure and Function (CSF)
Program Officer
Rodewald, Richard D
Project Start
2007-09-21
Project End
2011-08-31
Budget Start
2007-09-21
Budget End
2008-08-31
Support Year
1
Fiscal Year
2007
Total Cost
$278,620
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Biomedical Engineering
Type
Schools of Engineering
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
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