Identify the structural properties of TDP-43 C-terminal fragments associated with ALS

• Main Authors: Yeh-Yung Lin, 林燁雍
• Other Authors: Jen-Tse Huang
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/26467456337245555321

碩士 === 國立臺灣科技大學 === 工程技術研究所 === 98 === Many neurodegenerative diseases (NDDs), including Alzheimer’s disease (AD), Huntington’s disease (HD), Motor neuron disease (MND), Parkinson’s disease (PD), and Amyotrophic lateral sclerosis (ALS), have been realized to associate with inclusion body formation and protein aggregation of molecular and cellular mechanisms. These aggregates usually appear as fibril morphology and consist of β-sheet structure. ALS is the third common neuron degenerative cause of adult death, after AD and PD. It is also the most adult-onset motor neuron disease (MND), cause of progressive weakness, muscular wasting, and death within a few years. However, the exhaustive mechanism and the possible treatment for this disease remained unavailable. In 2006, TAR DNA-binding protein (TDP-43), containing 414 residues, was identified as the main sediments in the histopathological inclusion bodies of ALS and frontotemporal lobar degeneration (FTLD-U). Recent literatures have further indicated that the major component in the inclusions of ALS and FTLD patients were hyperphosphorylated TDP-43 C-terminal fragments. In order to understand the role of C-terminal domain of TDP-43 in ALS, we have synthesized four peptide fragments located in different regions of C-terminus to uncover the relationship between fibrial structure and aggregation state. Interestingly, only the D1 formed twisted fibrils after incubating in phosphate buffer for two weeks. D2, D3 and D4, on the other hand, were detected as amorphous aggregates by EM measurement. Moreover, two pathological mutant peptides, A315T and G294A, also had the ability to form fibrils that displayed the similar morphology with neuronal cytoplasmic inclusions (NCIs). In the meantime, we used the circular dichroism (CD) spectroscopy to trace the change of secondary structure. It revealed that only the G294A had significantly been altered. Moreover, we successfully identified the specific conformation of D1, A315T, and G294A peptide fragments by applying fluorescence and Raman spectroscopy. We found only G294A had strong emission with the addition of ThT. From the results of FT-Raman spectra, the aggregation of all three peptides belongs to amyloid structures. Base on these results, we proposed that the region (sequence: 287-322) contains many glycine repeats in C-terminus may play an important role in the fibril formation as well as aggregation formation.