Faculty Collaboration Database

1-Methyl-4-phenylpyridinium-induced apoptosis in cerebellar granule neurons is mediated by transferrin receptor iron-dependent depletion of tetrahydrobiopterin and neuronal nitric-oxide synthase-derived superoxide. J Biol Chem 2004 Apr 30;279(18):19099-112

Date

01/31/2004

Pubmed ID

14752097

DOI

10.1074/jbc.M400101200

Scopus ID

2-s2.0-2442504779 (requires institutional sign-in at Scopus site)   57 Citations

Abstract

In this study, we investigated the molecular mechanisms of toxicity of 1-methyl-4-phenylpyridinium (MPP(+)), an ultimate toxic metabolite of a mitochondrial neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, that causes Parkinson-like symptoms in experimental animals and humans. We used rat cerebellar granule neurons as a model cell system for investigating MPP(+) toxicity. Results show that MPP(+) treatment resulted in the generation of reactive oxygen species from inhibition of complex I of the mitochondrial respiratory chain, and inactivation of aconitase. This, in turn, stimulated transferrin receptor (TfR)-dependent iron signaling via activation of the iron-regulatory protein/iron-responsive element interaction. MPP(+) caused a time-dependent depletion of tetrahydrobiopterin (BH(4)) that was mediated by H(2)O(2) and transferrin iron. Depletion of BH(4) decreased the active, dimeric form of neuronal nitric-oxide synthase (nNOS). MPP(+)-mediated "uncoupling" of nNOS decreased *NO and increased superoxide formation. Pretreatment of cells with sepiapterin to promote BH(4) biosynthesis or cell-permeable iron chelator and TfR antibody to prevent iron-catalyzed BH(4) decomposition inhibited MPP(+) cytotoxicity. Preincubation of cerebellar granule neurons with nNOS inhibitor exacerbated MPP(+)-induced iron uptake, BH(4) depletion, proteasomal inactivation, and apoptosis. We conclude that MPP(+)-dependent aconitase inactivation, Tf-iron uptake, and oxidant generation result in the depletion of intracellular BH(4), leading to the uncoupling of nNOS activity. This further exacerbates reactive oxygen species-mediated oxidative damage and apoptosis. Implications of these results in unraveling the molecular mechanisms of neurodegenerative diseases (Parkinson's and Alzheimer's disease) are discussed.

Author List

Shang T, Kotamraju S, Kalivendi SV, Hillard CJ, Kalyanaraman B

Authors

Cecilia J. Hillard PhD Associate Dean, Center Director, Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin
Balaraman Kalyanaraman PhD Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

1-Methyl-4-phenylpyridinium
Aconitate Hydratase
Animals
Antioxidants
Apoptosis
Cerebellum
Electron Transport Complex I
Humans
Interneurons
Iron
Mitochondrial Proteins
Nitric Oxide Synthase
Nitric Oxide Synthase Type I
Parkinson Disease
Rats
Reactive Oxygen Species
Receptors, Transferrin
Signal Transduction
Superoxides