EFFECTS OF TAU MUTANTS ON THE MECHANICAL PROPERTIES OF MICROTUBULES
Kuang Wei, Dezhi Yu, Benjamin Lopez, Jamianne Wilcox, Megan Valentine.
University of California, Santa Barbara, Santa Barbara, CA.
Microtubules are dynamic cytoskeletal filaments that play important roles in intracellular transport and cell division. In cells, they are often stabilized by tau, a neural microtubule-associated protein that is critical for maintenance of a healthy nervous system. Several dementia disorders have been linked to mutations in the tau genes. In many cases, these tau mutants fail to bind to and stabilize microtubules, causing filament disintegration; however, there is a subclass of tau mutants that maintain strong microtubule binding, yet still cause neurological disease. The mechanical effects of this subclass are unknown. In order to gain a fundamental understanding in tau related neurological diseases, extensive studies on how tau proteins, particularly those mutants with strong binding, modulate microtubules are necessary. In this study, we focus on the changes in the mechanical properties of microtubules stabilized by different tau mutants. Using advanced microscopy, we will record movies of the fluctuations of fluorescently labeled microtubules subjected to thermal forces in vitro and determine their stiffness using spectral analysis of the microtubule shapes. To further study the interaction between tau and microtubules, we will also label tau with fluorescent dyes and monitor the binding and the motion of tau proteins on microtubules with laser-induced fluorescence microscopy. We will measure the binding affinity, the cooperativity of binding, and tau diffusion coefficient using different tau mutants and under different chemical conditions. Taken together, our data will provide an improved understanding in how tau modulates microtubule mechanics and its effects in tau related neurological diseases.