title: Reactive γ-ketoaldehydes promote protein misfolding and preamyloid oligomer formation in rapidly-activated atrial cells.
abstract: Rapid activation causes remodeling of atrial myocytes resembling that which occurs in experimental and human atrial fibrillation (AF). Using this cellular model, we previously observed transcriptional upregulation of proteins implicated in protein misfolding and amyloidosis. For organ-specific amyloidoses such as Alzheimer's disease, preamyloid oligomers (PAOs) are now recognized to be the primary cytotoxic species. In the setting of oxidative stress, highly-reactive lipid-derived mediators known as γ-ketoaldehydes (γ-KAs) have been identified that rapidly adduct proteins and cause PAO formation for amyloid β1-42 implicated in Alzheimer's. We hypothesized that rapid activation of atrial cells triggers oxidative stress with lipid peroxidation and formation of γ-KAs, which then rapidly crosslink proteins to generate PAOs. To investigate this hypothesis, rapidly-paced and control, spontaneously-beating atrial HL-1 cells were probed with a conformation-specific antibody recognizing PAOs. Rapid stimulation of atrial cells caused the generation of cytosolic PAOs along with a myocyte stress response (e.g., transcriptional upregulation of Nppa and Hspa1a), both of which were absent in control, unpaced cells. Rapid activation also caused the formation of superoxide and γ-KA adducts in atriomyocytes, while direct exposure of cells to γ-KAs resulted in PAO production. Increased cytosolic atrial natriuretic peptide (ANP), and the generation of ANP oligomers with exposure to γ-KAs and rapid atrial HL-1 cell stimulation, strongly suggest a role for ANP in PAO formation. Salicylamine (SA) is a small molecule scavenger of γ-KAs that can protect proteins from modification by these reactive compounds. PAO formation and transcriptional remodeling were inhibited when cells were stimulated in the presence of SA, but not with the antioxidant curcumin, which is incapable of scavenging γ-KAs. These results demonstrate that γ-KAs promote protein misfolding and PAO formation as a component of the atrial cell stress response to rapid activation, and they provide a potential mechanistic link between oxidative stress and atrial cell injury.
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Tatiana N
authors.initials: TN
authors.lastname: Sidorova
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Liudmila V
authors.initials: LV
authors.lastname: Yermalitskaya
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Mace
authors.affiliation: Departments of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: K Sam
authors.initials: KS
authors.lastname: Wells
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Olivier
authors.initials: O
authors.lastname: Boutaud
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Prinsen
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Sean S
authors.initials: SS
authors.lastname: Davies
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: L Jackson
authors.initials: LJ
authors.lastname: Roberts
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Dikalov
authors.affiliation: University of California, Irvine, Irvine, CA, USA.
authors.forename: Charles G
authors.initials: CG
authors.lastname: Glabe
authors.affiliation: Departments of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Venkataraman
authors.initials: V
authors.lastname: Amarnath
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: Joey V
authors.initials: JV
authors.lastname: Barnett
authors.affiliation: Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA. Electronic address: kathy.murray@vanderbilt.edu.
authors.forename: Katherine T
authors.initials: KT
authors.lastname: Murray
mesh_terms: D000447:Aldehydes / Q000494:pharmacology*; D000588:Amines / Q000494:pharmacology; D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D002304:Cardiac Pacing, Artificial; D002460:Cell Line; D003474:Curcumin / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D051379:Mice; D008954:Models, Biological; D018384:Oxidative Stress / Q000187:drug effects; D017510:Protein Folding / Q000187:drug effects*; D055503:Protein Multimerization; D013481:Superoxides / Q000378:metabolism
chemical_list: D000447:Aldehydes; D000588:Amines; D000682:Amyloid; D013481:Superoxides; D009320:Atrial Natriuretic Factor; D003474:Curcumin
keywords: Amyloidosis; Atrial HL-1 cells; Atrial natriuretic peptide; Levuglandin; Oxidant stress; Preamyloid oligomers; γ-ketoaldehyde