Digitized Honors Theses (2002-2017)

Date of Award

5-2015

Document Type

Undergraduate Thesis

Degree Name

BS

Department

Biomedical Sciences

Faculty Mentor

Troy Stevens, Christiaan Ochoa

Abstract

Microtubules spontaneously disassemble upon cold exposure. Cold-adapted animals express a microtubule-associated protein (MAP6) that prevents cold-induced microtubule disassembly. Some mammalian cells, including endothelial cells, also express MAP6, although its function in warm-blooded animals is unclear. Here, we tested the hypothesis that bacteria induce MAP6 stabilization of microtubules as a mechanism of inter-kingdom communication in endothelia. We report that Pseudomonas aeruginosa induces MAP6 translocation from the cytosol to microtubules; this effect occurs acutely upon bacterial inoculation and is not dependent upon Pseudomonas exoenzymes or a functional type ID secretion system. MAP6 microtubule stabilization does not prevent the T3SS exoenzyme Y from causing tau hyperphosphorylation, insolubility and microtubule breakdown, demonstrating two discrete microtubule populations with divergent physiological functions. Furthermore, MAP6-microtubule binding does not prevent exoenzyme Y from causing cell rounding leading to endothelial cell barrier disruption, and it does not influence calcium entry through store operated calcium entry channels. These studies provide the first evidence for a (patho-)physiological signal that induces MAP6 translocation from the cytosol to the microtubules in cells from warm-blooded animals. While our studies reveal that MAP6- microtubule binding represents a host response to infection, at present, the physiological function of the MAP6 dependent microtubule stabilization remains unclear, especially in the endothelium.

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