Synaptosomal toxicity and nucleophilic targets of 4-hydroxy-2-nonenal

Richard M. LoPachin, Brian C. Geohagen, Terrence Gavin

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

4-Hydroxy-2-nonenal (HNE) is an aldehyde by-product of lipid peroxidation that is presumed to play a primary role in certain neuropathogenic states (e.g., Alzheimer disease, spinal cord trauma). Although the molecular mechanism of neurotoxicity is unknown, proteomic analyses (e.g., tandem mass spectrometry) have demonstrated that this soft electrophile preferentially forms Michael-type adducts with cysteine sulfhydryl groups. In this study, we characterized HNE synaptosomal toxicity and evaluated the role of putative nucleophilic amino acid targets. Results show that HNE exposure of striatal synaptosomes inhibited 3H-dopamine membrane transport and vesicular storage. These concentration-dependent effects corresponded to parallel decreases in synaptosomal sulfhydryl content. Calculations of quantum mechanical parameters (softness, electrophilicity) that describe the interactions of an electrophile with its nucleophilic target indicated that the relative softness of HNE was directly related to both the second-order rate constant (k2) for sulfhydryl adduct formation and corresponding neurotoxic potency (IC50). Computation of additional quantum mechanical parameters that reflect the relative propensity of a nucleophile to interact with a given electrophile (chemical potential, nucleophilicity) indicated that the sulfhydryl thiolate state was the HNE target. In support of this, we showed that the rate of adduct formation was related to pH and that N-acetyl-L-cysteine, but not N-acetyl-L-lysine or β-alanyl-L-histidine, reduced in vitro HNE neurotoxicity. These data suggest that, like other type 2 alkenes, HNE produces nerve terminal toxicity by forming adducts with sulfhydryl thiolates on proteins involved in neurotransmission.

Original languageEnglish (US)
Pages (from-to)171-181
Number of pages11
JournalToxicological Sciences
Volume107
Issue number1
DOIs
StatePublished - 2009

Fingerprint

Toxicity
Corpus Striatum
Nucleophiles
Synaptosomes
Chemical potential
Acetylcysteine
Alkenes
Tandem Mass Spectrometry
4-hydroxy-2-nonenal
Spinal Cord Injuries
Histidine
Aldehydes
Synaptic Transmission
Proteomics
Lipid Peroxidation
Inhibitory Concentration 50
Lysine
Mass spectrometry
Cysteine
Byproducts

Keywords

  • α,β-unsaturated carbonyl
  • Acrolein
  • Alzheimer disease
  • Nerve terminal toxicity
  • Oxidative stress

ASJC Scopus subject areas

  • Toxicology

Cite this

Synaptosomal toxicity and nucleophilic targets of 4-hydroxy-2-nonenal. / LoPachin, Richard M.; Geohagen, Brian C.; Gavin, Terrence.

In: Toxicological Sciences, Vol. 107, No. 1, 2009, p. 171-181.

Research output: Contribution to journalArticle

LoPachin, Richard M. ; Geohagen, Brian C. ; Gavin, Terrence. / Synaptosomal toxicity and nucleophilic targets of 4-hydroxy-2-nonenal. In: Toxicological Sciences. 2009 ; Vol. 107, No. 1. pp. 171-181.
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abstract = "4-Hydroxy-2-nonenal (HNE) is an aldehyde by-product of lipid peroxidation that is presumed to play a primary role in certain neuropathogenic states (e.g., Alzheimer disease, spinal cord trauma). Although the molecular mechanism of neurotoxicity is unknown, proteomic analyses (e.g., tandem mass spectrometry) have demonstrated that this soft electrophile preferentially forms Michael-type adducts with cysteine sulfhydryl groups. In this study, we characterized HNE synaptosomal toxicity and evaluated the role of putative nucleophilic amino acid targets. Results show that HNE exposure of striatal synaptosomes inhibited 3H-dopamine membrane transport and vesicular storage. These concentration-dependent effects corresponded to parallel decreases in synaptosomal sulfhydryl content. Calculations of quantum mechanical parameters (softness, electrophilicity) that describe the interactions of an electrophile with its nucleophilic target indicated that the relative softness of HNE was directly related to both the second-order rate constant (k2) for sulfhydryl adduct formation and corresponding neurotoxic potency (IC50). Computation of additional quantum mechanical parameters that reflect the relative propensity of a nucleophile to interact with a given electrophile (chemical potential, nucleophilicity) indicated that the sulfhydryl thiolate state was the HNE target. In support of this, we showed that the rate of adduct formation was related to pH and that N-acetyl-L-cysteine, but not N-acetyl-L-lysine or β-alanyl-L-histidine, reduced in vitro HNE neurotoxicity. These data suggest that, like other type 2 alkenes, HNE produces nerve terminal toxicity by forming adducts with sulfhydryl thiolates on proteins involved in neurotransmission.",
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AB - 4-Hydroxy-2-nonenal (HNE) is an aldehyde by-product of lipid peroxidation that is presumed to play a primary role in certain neuropathogenic states (e.g., Alzheimer disease, spinal cord trauma). Although the molecular mechanism of neurotoxicity is unknown, proteomic analyses (e.g., tandem mass spectrometry) have demonstrated that this soft electrophile preferentially forms Michael-type adducts with cysteine sulfhydryl groups. In this study, we characterized HNE synaptosomal toxicity and evaluated the role of putative nucleophilic amino acid targets. Results show that HNE exposure of striatal synaptosomes inhibited 3H-dopamine membrane transport and vesicular storage. These concentration-dependent effects corresponded to parallel decreases in synaptosomal sulfhydryl content. Calculations of quantum mechanical parameters (softness, electrophilicity) that describe the interactions of an electrophile with its nucleophilic target indicated that the relative softness of HNE was directly related to both the second-order rate constant (k2) for sulfhydryl adduct formation and corresponding neurotoxic potency (IC50). Computation of additional quantum mechanical parameters that reflect the relative propensity of a nucleophile to interact with a given electrophile (chemical potential, nucleophilicity) indicated that the sulfhydryl thiolate state was the HNE target. In support of this, we showed that the rate of adduct formation was related to pH and that N-acetyl-L-cysteine, but not N-acetyl-L-lysine or β-alanyl-L-histidine, reduced in vitro HNE neurotoxicity. These data suggest that, like other type 2 alkenes, HNE produces nerve terminal toxicity by forming adducts with sulfhydryl thiolates on proteins involved in neurotransmission.

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