title: Aggregate-prone R120GCRYAB triggers multifaceted modifications of the thioredoxin system.
abstract: OBJECTIVE
  The human mutation R120G in the αB-crystallin (CRYAB) causes a multisystemic disease that is characterized by hypertrophic cardiomyopathy and cytoplasmic protein aggregates. In transgenic mice, human R120GCRYAB (hR120GTg) expression in heart sequentially modifies the REDOX status, in part by the activation of the nuclear factor, erythroid derived 2, like 2 (Nrf2). Thioredoxin system (TS) components are NRF2 target genes, so it could be hypothesized that TS was affected in hR120GTg mice.
  
  
  RESULTS
  Transgenic hearts overexpressed thioredoxin 1 (Trx1), which was identified by isotope coded affinity tag-mass spectrometry, among hundreds of peptides displaying an increased reduced/oxidized ratio. Coupled to this higher level of reduced cysteines, the activity of thioredoxin reductase 1 (TrxR1) was augmented by 2.5-fold. Combining mutiple experimental approaches, the enzymatic regulation of TrxR1 by a histone deacetylase 3 (HDAC3)-dependent level of acetylation was confirmed. In vitro and in vivo functional tests established that TrxR1 activity is required to mitigate aggregate development, and this could be mediated by Bcl-2-associated athanogene 3 (BAG3) as a potential TS substrate.
  
  
  CONCLUSIONS
  This study uncovers the compartmentalized changes and the involvement of TS in the cardiac stress response elicited by misfolded proteins such as R120GCRYAB. Our work suggests that R120GCRYAB triggers a defensive pathway acting through the newly identified interacting partners HDAC3, TrxR1, and BAG3 to counter aggregate growth. Therefore, those interactors may function as modifier genes contributing to the variable onset and expressivity of such human diseases. Furthermore, our work underscores the potential organismal effects of pharmacological interventions targeting TS and HDAC.
authors.affiliation: 1 Laboratory of Cardiac Disease, Redox Signaling and Cell Regeneration, Division of Cardiology, University of Utah School of Medicine , Salt Lake City, Utah.
authors.forename: Soumyajit
authors.initials: S
authors.lastname: Banerjee Mustafi
authors.forename: Julianne H
authors.initials: JH
authors.lastname: Grose
authors.forename: Huali
authors.initials: H
authors.lastname: Zhang
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Pratt
authors.forename: Junichi
authors.initials: J
authors.lastname: Sadoshima
authors.forename: Elisabeth S
authors.initials: ES
authors.lastname: Christians
authors.forename: Ivor J
authors.initials: IJ
authors.lastname: Benjamin
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D002312:Cardiomyopathy, Hypertrophic / Q000235:genetics*; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D007553:Isotope Labeling; D013058:Mass Spectrometry; D051379:Mice; D008822:Mice, Transgenic; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D010084:Oxidation-Reduction; D066263:Protein Aggregation, Pathological / Q000235:genetics*; D054481:Thioredoxin Reductase 1 / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism; D038203:alpha-Crystallin B Chain / Q000235:genetics*; D000099186:Histone Deacetylase 3
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D006655:Histone Deacetylases; D051267:NF-E2-Related Factor 2; D054481:Thioredoxin Reductase 1; D013879:Thioredoxins; D038203:alpha-Crystallin B Chain; D000099186:Histone Deacetylase 3; C498806:Bag3 protein, mouse; C059215:CRYAB protein, human; C495636:Nfe2l2 protein, mouse; C515559:Txn1 protein, mouse; C516112:Txn2 protein, mouse; C516125:Txnrd1 protein, mouse