Abstract
TAR DNA-binding protein (TDP-43) was identified as the major ubiquitinated component deposited in the inclusion bodies in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) in 2006. Later on, numerous ALS-related mutations were found in either the glycine or glutamine/asparagine-rich region on the TDP-43 C-terminus, which hinted on the importance of mutations on the disease pathogenesis. However, how the structural conversion was influenced by the mutations and the biological significance of these peptides remains unclear. In this work, various peptides bearing pathogenic or de novo designed mutations were synthesized and displayed their ability to form twisted amyloid fibers, cause liposome leakage, and mediate cellular toxicity as confirmed by transmission electron microscopy (TEM), circular dichroism (CD), Thioflavin T (ThT) assay, Raman spectroscopy, calcein leakage assay, and cell viability assay. We have also shown that replacing glycines with prolines, known to obstruct β-sheet formation, at the different positions in these peptides may influence the amyloidogenesis process and neurotoxicity. In these cases, GGG308PPP mutant was not able to form beta-amyloid, cause liposome leakage, nor jeopardized cell survival, which hinted on the importance of the glycines (308–310) during amyloidogenesis.
Highlights
TDP-43 (TAR DNA-binding protein) is the major pathological protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) [1,2]
Glycine to proline replacement in the critical sites in TDP-43 (GGG308PPP) suppressed the amyloidogenic process which further reduced neurotoxicity. Our results provided both the biophysical and biochemical information of TDP-43 C-terminus mutant peptides
We have previously reported that a specific fragment from TDP-43 C-terminus, D1, is able to form twisted fibers and bamyloid structure through the analysis of transmission electron microscopy (TEM) and circular dichroism (CD) [20]
Summary
TDP-43 (TAR DNA-binding protein) is the major pathological protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U) [1,2]. More than 40 pathological TDP-43 mutations were found in the C-terminal domain, which indicated the intrinsic disordered propensity of this region in TDP-43 proteinopathy [11]. A breakthrough in delineating the biological impact of the pathological mutation A315T in ALS patients has been characterized in detail. This mutant is able to promote protein aggregation, amyloid fibrillation, locomotive dysfunction, and motor neuron death combined with axonal damage, revealing the possible amyloidogenic and neurotoxic properties of TDP-43 mutants in ALS pathogenesis [17,18]. Though many mutations have been identified in this protein, their specific roles in TDP-43 proteinopathy as well as their biological significance remain vague
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
