Publication Date

5-2010

Type of Culminating Activity

Thesis - Boise State University Access Only

Degree Title

Master of Science in Biology

Department

Biology

Major Advisor

Troy Rohn, Ph.D.

Abstract

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.

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