Journal Article

Casein Kinase II Induced Polymerization of Soluble TDP-43 into Filaments Is Inhibited by Heat Shock Proteins

Davis, Mary, Petrucelli, Leonard, Lin, Wen-Lang, Tay, William, Carlomagno, Yari, Menkosky, Kyle, Zhang, Yongjie, Cook, Casey, Cao, Xiangkun, Dunmore, Judy, DeTure, Michael

2014

Overview

Trans-activation Response DNA-binding Protein-43 (TDP-43) lesions are observed in Amyotrophic Lateral Sclerosis (ALS), Frontotemporal Lobar Degeneration with ubiquitin inclusions (FTLD-TDP) and 25-50% of Alzheimer's Disease (AD) cases. These abnormal protein inclusions are composed of either amorphous TDP-43 aggregates or highly ordered filaments. The filamentous TDP-43 accumulations typically contain clean 10-12 nm filaments though wider 18-20 nm coated filaments may be observed. The TDP-43 present within these lesions is phosphorylated, truncated and ubiquitinated, and these modifications appear to be abnormal as they are linked to both a cellular heat shock response and microglial activation. The mechanisms associated with this abnormal TDP-43 accumulation are believed to result in a loss of TDP-43 function, perhaps due to the post-translational modifications or resulting from physical sequestration of the TDP-43. The formation of TDP-43 inclusions involves cellular translocation and conversion of TDP-43 into fibrillogenic forms, but the ability of these accumulations to sequester normal TDP-43 and propagate this behavior between neurons pathologically is mostly inferred. The lack of methodology to produce soluble full length TDP-43 and recapitulate this polymerization into filaments as observed in disease has limited our understanding of these pathogenic cascades. The protocols described here generate soluble, full-length and untagged TDP-43 allowing for a direct assessment of the impact of various posttranslational modifications on TDP-43 function. We demonstrate that Casein Kinase II (CKII) promotes the polymerization of this soluble TDP-43 into 10 nm diameter filaments that resemble the most common TDP-43 structures observed in disease. Furthermore, these filaments are recognized as abnormal by Heat Shock Proteins (HSPs) which can inhibit TDP-43 polymerization or directly promote TDP-43 filament depolymerization. These findings demonstrate CKII induces polymerization of soluble TDP-43 into filaments and Hsp90 promotes TDP-43 filament depolymerization. These findings provide rational for potential therapeutic intervention at these points in TDP-43 proteinopathies.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Activation / Alzheimer's disease / Amyotrophic lateral sclerosis / Animals / Biology / Brain research / Cascades / Casein / Casein kinase II / Casein Kinase II - pharmacology / Degeneration / Deoxyribonucleic acid / Depolymerization / Development and progression / Disease control / DNA / DNA-binding protein / DNA-Binding Proteins - chemistry / DNA-Binding Proteins - isolation & purification / DNA-Binding Proteins - metabolism / Filaments / Frontotemporal dementia / Frontotemporal Lobar Degeneration - metabolism / Frontotemporal Lobar Degeneration - pathology / Heat shock proteins / HSP90 Heat-Shock Proteins - metabolism / Hsp90 protein / Humans / Inclusion Bodies - drug effects / Inclusion Bodies - metabolism / Inclusion Bodies - ultrastructure / Inclusions / Kinases / Lesions / Medicine / Mice / Neurodegenerative diseases / Pathology / Phosphorylation - drug effects / Polymerization / Polymerization - drug effects / Post-translation / Protein Aggregation, Pathological - metabolism / Protein binding / Proteins / Reproducibility of Results / Rodents / Solubility / Translocation / Ubiquitin