title: Unraveling cellular phenotypes of novel TorsinA/TOR1A mutations.
abstract: A three-nucleotide (GAG) deletion (ΔE) in TorsinA (TOR1A) has been identified as the most common cause of dominantly inherited early-onset torsion dystonia (DYT1). TOR1A encodes a chaperone-like AAA+-protein localized in the endoplasmic reticulum. Currently, only three additional, likely mutations have been reported in single dystonia patients. Here, we report two new, putative TOR1A mutations (p.A14_P15del and p.E121K) that we examined functionally in comparison with wild-type (WT) protein and two known mutations (ΔE and p.R288Q). While inclusion formation is a characteristic feature for ΔE TOR1A, elevated levels of aggregates for other mutations were not observed when compared with WT TOR1A. WT and mutant TOR1A showed preferred degradation through the autophagy-lysosome pathway, which is most pronounced for p.A14_P15del, p.R288Q, and ΔE TOR1A. Notably, blocking of the autophagy pathway with bafilomycin resulted in a significant increase in inclusion formation in p.E121K TOR1A. In addition, all variants had an influence on protein stability. Although the p.A14_P15del mutation affects the proposed oligomerization domain of TOR1A, this mutation did not disturb the ability to dimerize. Our findings demonstrate functional changes for all four mutations on different levels. Thus, both diagnostic and research genetic screening of dystonia patients should not be limited to testing for the ∆E mutation.
authors.affiliation: Institute of Neurogenetics, University of Lübeck, Lübeck, Germany.
authors.forename: Franca
authors.initials: F
authors.lastname: Vulinovic
authors.forename: Katja
authors.initials: K
authors.lastname: Lohmann
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Rakovic
authors.forename: Philipp
authors.initials: P
authors.lastname: Capetian
authors.forename: Daniel
authors.initials: D
authors.lastname: Alvarez-Fischer
authors.forename: Alexander
authors.initials: A
authors.lastname: Schmidt
authors.forename: Anne
authors.initials: A
authors.lastname: Weißbach
authors.forename: Alev
authors.initials: A
authors.lastname: Erogullari
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Kaiser
authors.forename: Karin
authors.initials: K
authors.lastname: Wiegers
authors.forename: Andreas
authors.initials: A
authors.lastname: Ferbert
authors.forename: Arndt
authors.initials: A
authors.lastname: Rolfs
authors.forename: Christine
authors.initials: C
authors.lastname: Klein
authors.forename: Philip
authors.initials: P
authors.lastname: Seibler
mesh_terms: D000328:Adult; D017668:Age of Onset; D001343:Autophagy; D002460:Cell Line; D004422:Dystonia Musculorum Deformans / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D005260:Female; D005787:Gene Frequency; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D055503:Protein Multimerization; D055550:Protein Stability; D021381:Protein Transport; D059748:Proteolysis; D015398:Signal Transduction; D055815:Young Adult
chemical_list: D018832:Molecular Chaperones; C108175:TOR1A protein, human
keywords: DYT1; TOR1A; TorsinA; dystonia; endoplasmic reticulum; protein degradation; protein stability