Title page for etd-0821102-151102


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URN etd-0821102-151102
Author Yi-Chen Yen
Author's Email Address No Public.
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Department Institute of Biomedical Sciences
Year 2001
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Molecular Interaction of Tau and Microtubule
Date of Defense 2002-06-28
Page Count 78
Keyword
  • phosphorylation
  • tau protein
  • microtubule
  • Abstract Tau protein is one of the microtubule-associated proteins (MAPs) and mainly expressed in neuronal cells. It hasbeen demonstrated that Tau may play an important role in regulating microtubule dynamic in neurons. Structurally and functionally, Tau protein composed of regulatory projection domain in N-terninus and microtubule-binding domain in C-terminus. It has been shown that the biological function of Tau protein was regulated by phosphorylation and dephosphorylation. In Alzheimer’s disease (AD) brain, hyperphosphorylated Tau caused by over active kinases may contribute to the disassociation of Tau from microtubule and form the pathologically hallmarker, paired helical filaments (PHFs). The reason to study cdc2 and GSK3β is two folds. First, both cdc2 and GSK3β activities are raised abbrently in AD brain. Second, the phosphorylation sites of cdc2 and GSK3β have been identified as those in PHFs.These prompted us to regard cdc2 and GSK3β as candidates that hyperphosphorylated Tau in AD.
    In the following study, we used immunofluorescence analysis, co-immunoprecipitation and GST-fusion protein pull down assay to clarify the subcellular localization of Tau. We also shown that the interaction between tubulin withfull length Tau (Tau WT) and some Tau mutants that we found that not only Tau WT, but also N-terminus of Tau (Tau-N) and C-terminus of Tau (Tau-C) can bind to tubulin. Surprisingly, we observed that a fragment of N-terminus, Tau 122-244, localized in nucleus. Furthermore, we used tubulin assembly assay to test if tau or its mutants can promote tubulin assembly in vitro. Results showed that only Tau WT can promote tubulin assembly in vitro but not Tau-N or Tau-C. Although Tau-N or Tau-C can bind to tubulin in vivo and in vitro, these mutants did not remain the ability to promote tubulin assembly that suggested both functional domains, N-terminus and C-terminus of Tau, are necessary and essential for the biological function of Tau. On the other hand, we used of phosphorylation assay and site directed mutagenesis to demonstrate that T231 of Tau is one of important phosphorylation sites of cdc2 and GSK3β. Finally, we used tubulin assembly assay to show that phosphorylated Tau by GSK3β can negatively regulate the ability of Tau to promote tubulin assembly that indicated that the phosphorylation at T231 may play a role in regulating Tau.
    Advisory Committee
  • Wen-Chun Hung - chair
  • Jiin-Tsuey Cheng - co-chair
  • Pei-Jung Lu - advisor
  • Files
  • etd-0821102-151102.pdf
  • indicate in-campus access immediately and off_campus access in a year
    Date of Submission 2002-08-21

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