Journal Article

Involvment of Cytosolic and Mitochondrial GSK-3β in Mitochondrial Dysfunction and Neuronal Cell Death of MPTP/MPP+-Treated Neurons

Petit-Paitel, Agnès, Chabry, Joëlle, Brau, Frédéric, Cazareth, Julie

2009

Overview

Aberrant mitochondrial function appears to play a central role in dopaminergic neuronal loss in Parkinson's disease (PD). 1-methyl-4-phenylpyridinium iodide (MPP+), the active metabolite of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), is a selective inhibitor of mitochondrial complex I and is widely used in rodent and cell models to elicit neurochemical alterations associated with PD. Recent findings suggest that Glycogen Synthase Kinase-3β (GSK-3β), a critical activator of neuronal apoptosis, is involved in the dopaminergic cell death. In this study, the role of GSK-3β in modulating MPP+-induced mitochondrial dysfunction and neuronal death was examined in vivo, and in two neuronal cell models namely primary cultured and immortalized neurons. In both cell models, MPTP/MPP+ treatment caused cell death associated with time- and concentration-dependent activation of GSK-3β, evidenced by the increased level of the active form of the kinase, i.e. GSK-3β phosphorylated at tyrosine 216 residue. Using immunocytochemistry and subcellular fractionation techniques, we showed that GSK-3β partially localized within mitochondria in both neuronal cell models. Moreover, MPP+ treatment induced a significant decrease of the specific phospho-Tyr216-GSK-3β labeling in mitochondria concomitantly with an increase into the cytosol. Using two distinct fluorescent probes, we showed that MPP+ induced cell death through the depolarization of mitochondrial membrane potential. Inhibition of GSK-3β activity using well-characterized inhibitors, LiCl and kenpaullone, and RNA interference, prevented MPP+-induced cell death by blocking mitochondrial membrane potential changes and subsequent caspase-9 and -3 activation. These results indicate that GSK-3β is a critical mediator of MPTP/MPP+-induced neurotoxicity through its ability to regulate mitochondrial functions. Inhibition of GSK-3β activity might provide protection against mitochondrial stress-induced cell death.

• Publisher: Public Library of Science
• Subject: Aberration / Activation / Animal models / Apoptosis / Bipolar disorder / Brain / Caspase / Caspase-9 / Cell Biology/Cellular Death and Stress Responses / Cell Biology/Neuronal Signaling Mechanisms / Cell culture / Cell death / Cytosol / Depolarization / DNA probes / Dopamine / Dopamine receptors / Electron transport chain / Fluorescence / Fluorescent indicators / Fractionation / Gene expression / Glycogen / Glycogen synthase kinase 3 / Immunocytochemistry / Immunoglobulins / Inhibition / Iodides / Kinases / Life Sciences / Lithium chloride / Membrane potential / Metabolites / Mitochondria / Mortality / Movement disorders / MPP / Neurodegenerative diseases / Neurological Disorders/Movement Disorders / Neurological Disorders/Neuropharmacology / Neurons / Neuroscience/Neurobiology of Disease and Regeneration / Neuroscience/Neuronal Signaling Mechanisms / Neurotoxicity / Oxidative stress / Parkinson's disease / Pathogenesis / Permeability / Phosphorylation / Psychiatry / Ribonucleic acid / RNA / Rodents / Signal transduction / Tyrosine