title: ALS-FTLD associated mutations of SQSTM1 impact on Keap1-Nrf2 signalling.
abstract: The transcription factor Nrf2 and its repressor protein Keap1 play key roles in the regulation of antioxidant stress responses and both Keap1-Nrf2 signalling and oxidative stress have been implicated in the pathogenesis of the ALS-FTLD spectrum of neurodegenerative disorders. The Keap1-binding partner and autophagy receptor SQSTM1/p62 has also recently been linked genetically to ALS-FTLD, with some missense mutations identified in patients mapping within or close to its Keap1-interacting region (KIR, residues 347-352). Here we report the effects on protein function of four different disease associated mutations of SQSTM1/p62 which affect the KIR region. Only mutations mapping precisely to the KIR (P348L and G351A) were associated with a loss of Keap1 binding in co-immunoprecipitations comparable to wild-type SQSTM1/p62. These selective effects on Keap1 recognition were entirely rational based on protein structural models. Consistent with impaired Keap1 binding, the P348L and G351A KIR mutants showed reduced ability to activate Nrf2 signalling compared to wild-type SQSTM1/p62 in antioxidant response element (ARE)-luciferase reporter assays. The results suggest that SQSTM1 mutations within the KIR of SQSTM1/p62 contribute to aetiology of some cases of ALS-FTLD through a mechanism involving aberrant expression or regulation of oxidative response genes.
authors.affiliation: School of Life Sciences, University of Nottingham, UK. Electronic address: alice.goode@nottingham.ac.uk.
authors.forename: Alice
authors.initials: A
authors.lastname: Goode
authors.affiliation: Harry Perkins Institute of Medical Research, University of Western Australia, Australia; Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia.
authors.forename: Sarah
authors.initials: S
authors.lastname: Rea
authors.affiliation: Harry Perkins Institute of Medical Research, University of Western Australia, Australia; Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia.
authors.forename: Melanie
authors.initials: M
authors.lastname: Sultana
authors.affiliation: School of Life Sciences, University of Nottingham, UK.
authors.forename: Barry
authors.initials: B
authors.lastname: Shaw
authors.affiliation: Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham, UK.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Searle
authors.affiliation: School of Life Sciences, University of Nottingham, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Layfield
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics*; D001665:Binding Sites; D057174:Frontotemporal Lobar Degeneration / Q000235:genetics*; D057809:HEK293 Cells; D006801:Humans; D000072019:Kelch-Like ECH-Associated Protein 1 / Q000378:metabolism*; D020125:Mutation, Missense; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D011485:Protein Binding; D020218:Response Elements; D000071456:Sequestosome-1 Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
chemical_list: C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein
keywords: ALS-FTLD; Keap1-Nrf2; Oxidative stress; SQSTM1/p62