PTK2/FAK regulates UPS impairment via SQSTM1/p62 phosphorylation in TARDBP/TDP-43 proteinopathies

Autophagy. 2020 Aug;16(8):1396-1412. doi: 10.1080/15548627.2019.1686729. Epub 2019 Nov 5.

Abstract

TARDBP/TDP-43 (TAR DNA binding protein) proteinopathies are a common feature in a variety of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), frontotemporal lobar degeneration (FTLD), and Alzheimer disease (AD). However, the molecular mechanisms underlying TARDBP-induced neurotoxicity are largely unknown. In this study, we demonstrated that TARDBP proteinopathies induce impairment in the ubiquitin proteasome system (UPS), as evidenced by an accumulation of ubiquitinated proteins and a reduction in proteasome activity in neuronal cells. Through kinase inhibitor screening, we identified PTK2/FAK (PTK2 protein tyrosine kinase 2) as a suppressor of neurotoxicity induced by UPS impairment. Importantly, PTK2 inhibition significantly reduced ubiquitin aggregates and attenuated TARDBP-induced cytotoxicity in a Drosophila model of TARDBP proteinopathies. We further identified that phosphorylation of SQSTM1/p62 (sequestosome 1) at S403 (p-SQSTM1 [S403]), a key component in the autophagic degradation of poly-ubiquitinated proteins, is increased upon TARDBP overexpression and is dependent on the activation of PTK2 in neuronal cells. Moreover, expressing a non-phosphorylated form of SQSTM1 (SQSTM1S403A) significantly repressed the accumulation of insoluble poly-ubiquitinated proteins and neurotoxicity induced by TARDBP overexpression in neuronal cells. In addition, TBK1 (TANK binding kinase 1), a kinase that phosphorylates S403 of SQSTM1, was found to be involved in the PTK2-mediated phosphorylation of SQSTM1. Taken together, our data suggest that the PTK2-TBK1-SQSTM1 axis plays a critical role in the pathogenesis of TARDBP by regulating neurotoxicity induced by UPS impairment. Therefore, targeting the PTK2-TBK1-SQSTM1 axis may represent a novel therapeutic intervention for neurodegenerative diseases with TARDBP proteinopathies.Abbreviations: ALP: macroautophagy/autophagy lysosomal pathway; ALS: amyotrophic lateral sclerosis; ATXN2: ataxin 2; BafA1: bafilomycin A1; cCASP3: cleaved caspase 3; CSNK2: casein kinase 2; FTLD: frontotemporal lobar degeneration; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; OPTN: optineurin; PTK2/FAK: PTK2 protein tyrosine kinase 2; SQSTM1/p62: sequestosome 1; TARDBP/TDP-43: TAR DNA binding protein; TBK1: TANK binding kinase 1; ULK1: unc-51 like autophagy activating kinase 1; UPS: ubiquitin-proteasome system.

Keywords: Amyotrophic lateral sclerosis; PTK2/FAK; SQSTM1/p62; TARDBP/TDP-43; ubiquitin-proteasome system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy / drug effects
  • Behavior, Animal / drug effects
  • DNA-Binding Proteins / metabolism
  • Down-Regulation / drug effects
  • Drosophila melanogaster / metabolism
  • Focal Adhesion Kinase 1 / antagonists & inhibitors
  • Focal Adhesion Kinase 1 / genetics
  • Focal Adhesion Kinase 1 / metabolism*
  • Mice
  • Models, Biological
  • Mutation / genetics
  • Neurotoxins / toxicity
  • Phosphorylation / drug effects
  • Phosphoserine / metabolism
  • Protein Serine-Threonine Kinases / metabolism
  • Sequestosome-1 Protein / metabolism*
  • Solubility
  • TDP-43 Proteinopathies / metabolism*
  • Ubiquitinated Proteins / metabolism
  • Unfolded Protein Response* / drug effects

Substances

  • DNA-Binding Proteins
  • Neurotoxins
  • Sequestosome-1 Protein
  • TDP-43 protein, mouse
  • Ubiquitinated Proteins
  • Phosphoserine
  • Tbk1 protein, mouse
  • Focal Adhesion Kinase 1
  • Protein Serine-Threonine Kinases

Grants and funding

This research was supported by the Korea Brain Research Institute funded by Ministy of Science and ICT [grant number: 19-BR-02-03, 19-BR-02-04, 19-BR-01-01]; Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health and Welfare [grant number: HI14C1135, HI15C1928, HI18C1241]; Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT [grant number: NRF-2017R1C1B2007941, NRF-2017R1C1B1008825]; the DGIST R&D Program funded by the Ministry of Science and ICT [grant number: 16-BD-0402 to S.B.L]; Soonchunhyang University Research Fund[to Kiyoung Kim].