lithium-chloride and Parkinson-Disease

Topics: Aged; Antiparkinson Agents; Female; Follow-Up Studies; Humans; Levodopa; Lithium Chloride; Male; Middle Aged; Parkinson Disease

Hyperphosphorylated tau protein is the main component of neurofibrillary tangles found in Alzheimer's disease and Parkinson's disease (PD). Mutations in DJ-1 have been identified as the causative gene for Parkinson's disease 7 (PARK7)-linked PD. DJ-1L166P and DJ-1D149A, two types of DJ-1 mutations, are most commonly studied as the loss-of-function mutations responsible for early-onset familial PD. Whether mutations in DJ-1 result in tauopathy is as yet unknown. In this study, we found that the L166P and D149A mutant isoforms of DJ-1 associated with familial PD cause tau phosphorylation at Ser202, Ser262, and PHF1 (396/404) sites in neuroblastoma 2a cells. Glycogen synthase kinase (GSK)-3β phosphorylation at serine 9 (Ser9) decreases around 50 % in DJ-1L166P- or DJ-1D149A-transfected cells, while there is no change in total levels of GSK-3β. Our results also indicate that overexpression of DJ-1L166P or DJ-1D149A leads to a significant decrease in the level of phosphorylation of Akt at Thr308, which plays a critical role in phosphorylating GSK-3β at Ser9 and inhibiting its kinase activity. Importantly, insulin, the activator for Akt, effectively attenuates the reduced phosphorylation level of GSK-3β at Ser9 induced by DJ-1L166P. Neither the expression of cyclin-dependent kinase 5 nor the level of PP2A activity was found to have changed, suggesting that the familial PD-associated DJ-1L166P and DJ-1D149A mutations increase tau phosphorylation by increasing the activity of GSK-3β. Finally, we found that administration of lithium chloride, a well-known GSK-3β inhibitor, resulted in decreased levels of phosphorylated tau in DJ-1L166P-transfected cells.

Topics: Animals; Cell Line, Tumor; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Lithium Chloride; Mice; Mutation, Missense; Oncogene Proteins; Parkinson Disease; Peroxiredoxins; Phosphorylation; Protein Deglycase DJ-1; Proto-Oncogene Proteins c-akt; tau Proteins

Dopaminergic neurons are lost mainly through apoptosis in Parkinson's disease. Insulin like growth factor-1 (IGF-1) inhibits apoptosis in a wide variety of tissues. Here we have shown that IGF-1 protects PC12 cells from toxic effects of 1-methyl-4-phenylpyridiniumion (MPP(+)). Treatment of PC12 cells with recombinant human IGF-1 significantly decreased apoptosis caused by MPP(+) as measured by acridine orange/ethidium bromide staining. IGF-1 treatment induced sustained phosphorylation of glycogen synthase kinase-3beta (GSK-3beta) as shown by western blot analysis. The anti-apoptotic effect of IGF-1 was abrogated by LY294002, which indirectly inhibits phosphorylation of GSK-3beta. Lithium chloride (LiCl), a known inhibitor of GSK-3beta, also blocked MPP(+)-induced apoptosis. Finally, although IGF-1 enhanced phosphorylation of extracellular signal-regulated kinases ERK1 and 2 (ERK1/2), PD98059, a specific inhibitor of ERK1/2, did not alter the survival effect of IGF-1. Thus, our findings indicate that IGF-1 protects PC12 cells exposed to MPP(+) from apoptosis via the GSK-3beta signaling pathway.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Animals; Apoptosis; Blotting, Western; Cell Survival; Chromones; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Flavonoids; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Insulin-Like Growth Factor I; Lithium Chloride; Morpholines; Neurotoxins; Parkinson Disease; PC12 Cells; Protein Kinase Inhibitors; Rats; Recombinant Proteins

The causes of sporadic Parkinson's disease (PD) are poorly understood. 6-Hydroxydopamine (6-OHDA), a PD mimetic, is widely used to model this neurodegenerative disorder in vitro and in vivo; however, the underlying mechanisms remain incompletely elucidated. We demonstrate here that 6-OHDA evoked endoplasmic reticulum (ER) stress, which was characterized by an up-regulation in the expression of GRP78 and GADD153 (Chop), cleavage of procaspase-12, and phosphorylation of eukaryotic initiation factor-2 alpha in a human dopaminergic neuronal cell line (SH-SY5Y) and cultured rat cerebellar granule neurons (CGNs). Glycogen synthase kinase-3 beta (GSK3beta) responds to ER stress, and its activity is regulated by phosphorylation. 6-OHDA significantly inhibited phosphorylation of GSK3beta at Ser9, whereas it induced hyperphosphorylation of Tyr216 with little effect on GSK3beta expression in SH-SY5Y cells and PC12 cells (a rat dopamine cell line), as well as CGNs. Furthermore, 6-OHDA decreased the expression of cyclin D1, a substrate of GSK3beta, and dephosphorylated Akt, the upstream signaling component of GSK3beta. Protein phosphatase 2A (PP2A), an ER stress-responsive phosphatase, was involved in 6-OHDA-induced GSK3beta dephosphorylation (Ser9). Blocking GSK3beta activity by selective inhibitors (lithium, TDZD-8, and L803-mts) prevented 6-OHDA-induced cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP), DNA fragmentations and cell death. With a tetracycline (Tet)-controlled TrkB inducible system, we demonstrated that activation of TrkB in SH-SY5Y cells alleviated 6-OHDA-induced GSK3beta dephosphorylation (Ser9) and ameliorated 6-OHDA neurotoxicity. TrkB activation also protected CGNs against 6-OHDA-induced damage. Although antioxidants also offered neuroprotection, they had little effect on 6-OHDA-induced GSK3beta activation. These results suggest that GSK3beta is a critical intermediate in pro-apoptotic signaling cascades that are associated with neurodegenerative diseases, thus providing a potential target site amenable to pharmacological intervention.

Topics: Animals; Apoptosis; Brain-Derived Neurotrophic Factor; CCAAT-Enhancer-Binding Proteins; Cells, Cultured; Cerebellar Cortex; Cyclin D1; Endoplasmic Reticulum Chaperone BiP; Enzyme Inhibitors; Eukaryotic Initiation Factor-2; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Heat-Shock Proteins; Humans; Lithium Chloride; Molecular Chaperones; Nerve Degeneration; Nerve Tissue Proteins; Neurons; Oxidopamine; Parkinson Disease; PC12 Cells; Phosphoprotein Phosphatases; Phosphorylation; Protein Phosphatase 2; Protein Processing, Post-Translational; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Rats; Receptor, trkB; Signal Transduction; Thiadiazoles; Transcription Factor CHOP; Transcription Factors