title: Enhanced autophagy from chronic toxicity of iron and mutant A53T α-synuclein: implications for neuronal cell death in Parkinson disease.
abstract: Parkinson disease (PD), a prevalent neurodegenerative motor disorder, is characterized by the rather selective loss of dopaminergic neurons and the presence of α-synuclein-enriched Lewy body inclusions in the substantia nigra of the midbrain. Although the etiology of PD remains incompletely understood, emerging evidence suggests that dysregulated iron homeostasis may be involved. Notably, nigral dopaminergic neurons are enriched in iron, the uptake of which is facilitated by the divalent metal ion transporter DMT1. To clarify the role of iron in PD, we generated SH-SY5Y cells stably expressing DMT1 either singly or in combination with wild type or mutant α-synuclein. We found that DMT1 overexpression dramatically enhances Fe(2+) uptake, which concomitantly promotes cell death. This Fe(2+)-mediated toxicity is aggravated by the presence of mutant α-synuclein expression, resulting in increased oxidative stress and DNA damage. Curiously, Fe(2+)-mediated cell death does not appear to involve apoptosis. Instead, the phenomenon seems to occur as a result of excessive autophagic activity. Accordingly, pharmacological inhibition of autophagy reverses cell death mediated by Fe(2+) overloading. Taken together, our results suggest a role for iron in PD pathogenesis and provide a mechanism underlying Fe(2+)-mediated cell death.
authors.affiliation: Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
authors.forename: Katherine C M
authors.initials: KC
authors.lastname: Chew
authors.forename: Eng-Tat
authors.initials: ET
authors.lastname: Ang
authors.forename: Yee Kit
authors.initials: YK
authors.lastname: Tai
authors.forename: Fai
authors.initials: F
authors.lastname: Tsang
authors.forename: Shun Qiang
authors.initials: SQ
authors.lastname: Lo
authors.forename: Elijah
authors.initials: E
authors.lastname: Ong
authors.forename: Wei-Yi
authors.initials: WY
authors.lastname: Ong
authors.forename: Han-Ming
authors.initials: HM
authors.lastname: Shen
authors.forename: Kah-Leong
authors.initials: KL
authors.lastname: Lim
authors.forename: Valina L
authors.initials: VL
authors.lastname: Dawson
authors.forename: Ted M
authors.initials: TM
authors.lastname: Dawson
authors.forename: Tuck Wah
authors.initials: TW
authors.lastname: Soong
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D027682:Cation Transport Proteins / Q000378:metabolism; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism / Q000633:toxicity*; D050505:Mutant Proteins / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects / Q000473:pathology* / Q000648:ultrastructure; D018384:Oxidative Stress / Q000187:drug effects; D010300:Parkinson Disease / Q000473:pathology*; D010588:Phagosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D051844:alpha-Synuclein / Q000633:toxicity*; D000099236:Solute Carrier Family 11, Member 2
chemical_list: D027682:Cation Transport Proteins; D045304:Cytochromes c; D007501:Iron; D050505:Mutant Proteins; D046988:Proteasome Endopeptidase Complex; D025801:Ubiquitin; D051844:alpha-Synuclein; D000099236:Solute Carrier Family 11, Member 2