TAR DNA-binding protein 43 kDa (TDP-43) is the major aggregating disease protein in amyotrophic lateral sclerosis (ALS). Over 90% of ALS cases exhibit pathological lesions containing detergent insoluble deposits of phosphorylated, truncated, and ubiquitinated TDP-43 protein. TDP-43 phosphorylated at S409/410 (pS409/410) is the most consistent, robust, and specific neuropathological feature of ALS suggesting a phosphorylated TDP-43 (pTDP) mediated cascade of neurotoxicity. Furthermore pTDP has been shown to influence the aggregation of TDP-43 in cultured cells and in human ALS cases. Our previous work demonstrated pS409/410 TDP-43 mediates motor neuron toxicity of familial ALS-causing TDP-43 mutations. Kinases regulating TDP-43 phosphorylation present an attractive target for therapeutic intervention in ALS. We have identified a well-conserved TDP-43- active kinase with translational potential known as tau tubulin kinase 1 (TTBK1). Identification of brain penetrant TTBK1 inhibitors may ultimately provide a viable drug development strategy. We hypothesize that increased TDP-43 phosphorylation drives motor neuron degeneration in ALS and that blocking pTDP accumulation by inhibiting TTBK1 will protect against TDP-43 mediated neurodegeneration in ALS. Three integrated specific aims are proposed: 1) Identification of TTBK1 selective kinase inhibitors. 2) Optimization of TTBK1 selective inhibitors and validation of selective compounds in a cellular model of pTDP accumulation. 3) Validation of the role of TTBK1 in the formation of pTDP using TTBK1 knockout mice and an existing transgenic model of TDP-43 proteinopathy. The studies proposed here will set the stage for development of TTBK1 selective inhibitors as a candidate therapeutic approach for ALS.

Public Health Relevance

To date no clinical trials for ALS have specifically targeted pathological TDP-43, which is the primary neuropathological lesion evident in degenerating motor neurons in over 90% of sporadic ALS cases and the majority of familial ALS cases. To fill this gap, we propose to develop neuroprotective strategies targeting pathological TDP-43 in ALS. Specifically, we propose to inhibit tau tubulin kinase 1 (TTBK1), a kinase known to increase TDP-43 pathogenicity via phosphorylation. The new compounds identified will serve as research tools, provide proof-of-concept that pTDP is a valid target for therapeutic intervention, and support future development of TTBK1 selective kinase inhibitors for treating ALS.

Agency
National Institute of Health (NIH)
Institute
Veterans Affairs (VA)
Type
Non-HHS Research Projects (I01)
Project #
5I01BX003755-04
Application #
9898277
Study Section
Neurobiology E (NURE)
Project Start
2017-04-01
Project End
2021-03-31
Budget Start
2020-04-01
Budget End
2021-03-31
Support Year
4
Fiscal Year
2020
Total Cost
Indirect Cost
Name
VA Puget Sound Healthcare System
Department
Type
DUNS #
020232971
City
Seattle
State
WA
Country
United States
Zip Code
98108