title: Probing mechanisms of axonopathy. Part I: Protein targets of 1,2-diacetylbenzene, the neurotoxic metabolite of aromatic solvent 1,2-diethylbenzene.
abstract: Motor neuron axonopathy in diseases such as amyotrophic lateral sclerosis can be modeled and probed with neurotoxic chemicals that induce similar patterns of pathology, such as axonal spheroids that represent focal accumulation of anterogradely transported neurofilaments (NFs). The aromatic gamma-diketone-like 1,2-diacetylbenzene (1,2-DAB), but not its 1,3-DAB isomer, reacts with epsilon-amino- or sulfyhydryl groups of (neuro)proteins, forms adducts, and causes NFs to accumulate at proximal sites of elongate motor axons. We exploit the protein-reactive properties of neurotoxic 1,2-DAB versus the nonprotein-reactive properties of non-neurotoxic 1,3-DAB to unveil proteomic changes associated with this type of pathology. We used two-dimensional differential in-gel electrophoresis (2D-DIGE), matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry to analyze the lumbosacral spinal cord proteome of adult Sprague-Dawley rats treated systemically with 20 mg/kg/day 1,2-DAB, equimolar dose of 1,3-DAB, or equivalent volume of vehicle (saline containing 2% acetone), 5 days a week, for 2 weeks. 1,2-DAB significantly altered the expression of protein disulfide isomerase, an enzyme involved in protein folding, and gelsolin, an actin-capping and -severing protein. Modifications of these two proteins have been incriminated in the pathogenesis of nerve fiber degeneration. Protein-reactive and neurotoxic 1,2-DAB appears to be excellent tool to dissect mechanisms of nerve fiber (axon) degeneration.
authors.affiliation: Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, 3181 S.W. Jackson Park Road, mail code L606, Portland, OR 97239, USA. tshalad@ohsu.edu
authors.forename: Desire
authors.initials: D
authors.lastname: Tshala-Katumbay
authors.forename: Victor
authors.initials: V
authors.lastname: Monterroso
authors.forename: Robert
authors.initials: R
authors.lastname: Kayton
authors.forename: Michael
authors.initials: M
authors.lastname: Lasarev
authors.forename: Mohammad
authors.initials: M
authors.lastname: Sabri
authors.forename: Peter
authors.initials: P
authors.lastname: Spencer
mesh_terms: D000098:Acetophenones / Q000633:toxicity*; D000818:Animals; D001369:Axons / Q000187:drug effects* / Q000473:pathology; D001555:Benzene Derivatives / Q000378:metabolism*; D001835:Body Weight / Q000187:drug effects; D015180:Electrophoresis, Gel, Two-Dimensional; D018260:Gelsolin / Q000032:analysis*; D008297:Male; D019704:Protein Disulfide-Isomerases / Q000032:analysis*; D040901:Proteomics; D051381:Rats; D017207:Rats, Sprague-Dawley; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013116:Spinal Cord / Q000737:chemistry / Q000187:drug effects* / Q000473:pathology
chemical_list: D000098:Acetophenones; D001555:Benzene Derivatives; D018260:Gelsolin; C064750:1,2-diethylbenzene; C048792:1,2-diacetylbenzene; D019704:Protein Disulfide-Isomerases