Caspase Activation in Neurodegenerative Diseases Classified as Tauopathies and Alpha-Synucleinopathies: Caspase-Cleaved TAR DNA-Binding Protein-43 in Pick's Disease Parkinson's Disease, and Dementia with Lewy Bodies
Type of Culminating Activity
Thesis - Boise State University Access Only
Master of Science in Biology
Troy Rohn, Ph.D.
TAR DNA-binding protein-43 (TDP-43) proteinopathies are classified based upon the extent of modified TDP-43 and include a growing number of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration with ubiquitin immunoreactive, tau-negative inclusions (FTLD-U) and FTLD with motor neuron disease (FTLD-MND), and most recently Alzheimer’s disease (AD).
To examine whether proteolytic modifications of TDP-43 are a relevant finding in Pick’s disease (PiD), Parkinson’s disease (PD), and dementia with Lewy Bodies (DLB), I utilized a novel site-directed caspase-cleavage antibody based upon a known caspase-3 cleavage consensus site within TDP-43 at position 219.
Application of this antibody, termed TDP caspase-cleavage product antibody (TDPccp) to postmortem Pick’s disease brain sections revealed the presence of caspase-cleaved TDP-43 in Pick and Hirano bodies predominantly within region CA1 of the hippocampus. Co-localization of TDPccp with PHF-1, a general marker for Pick bodies, as well as with an antibody to caspase-cleaved tau (TauC3) was evident within the hippocampus. A semi-quantitative analysis indicated that approximately 21% and 79% of the Pick bodies identified in area CA1 contained caspase-cleaved TDP-43 or caspase-cleaved tau, respectively. Of interest was the lack of co-localization of TDPccp with PHF-1 in Pick bodies within the dentate gyrus.
Application of the TDPccp antibody to postmortem brain sections from PD and DLB revealed the presence of caspase-cleaved TDP-43 in Lewy bodies and Hirano bodies in all cases examined. Co-localization of TDPccp with an antibody to alpha-synuclein (α-Syn), which served as a general marker for Lewy bodies, was evident within the substantia nigra in both alpha-synucleinopathies. Interestingly, the TDPccp antibody detected a greater number of Lewy bodies in PD and DLB compared to the α-Syn antibody. In addition, a semi-quantitative analysis in both diseases confirmed this finding by indicating that the percent of caspase-cleaved TDP-43 single-labeled Lewy bodies was approximately twice the percent that of α-Syn labeling (in DLB 13.4% vs. 5.5%, while in PD 34.6% vs. 17.6%, respectively).
Collectively, these data have identified modified TDP-43 as a component of Pick and Hirano bodies that is restricted to area CA1 in Pick’s disease. The relative paucity of caspase-cleaved TDP-43 found within Pick bodies in comparison to caspase-cleaved tau suggests that TDP-43 and its modification by caspases is most likely not a contributing factor leading to Pick body formation in PiD. On the other hand, these data have identified caspase-cleaved TDP-43 as a primary component of Lewy and Hirano bodies in PD and DLB, α-synucleinopathies, and suggest the TDPccp antibody is an effective marker for the detection of Lewy bodies in these neurodegenerative diseases.
Kokoulina, Polina, "Caspase Activation in Neurodegenerative Diseases Classified as Tauopathies and Alpha-Synucleinopathies: Caspase-Cleaved TAR DNA-Binding Protein-43 in Pick's Disease Parkinson's Disease, and Dementia with Lewy Bodies" (2010). Boise State University Theses and Dissertations. Paper 105.