[Oxidative stress and Parkinson's disease: mechanisms and perspectives of treatment]

The Neuroprotective Effect of Steroid Receptor Coactivator-Interacting Protein (SIP) in Astrocyte Model of 1-Methyl-4-Phenylpyridinium (MPP⁺)-Induced Parkinson's Disease

Background

The purpose of this study was to investigate the role and mechanism of steroid receptor coactivator-interacting protein (SIP) in an astrocyte model of 1-methyl-4-phenylpyridinium (MPP⁺)-induced Parkinson’s disease.

Material/Methods

To perform our study, a Parkinson’s disease cell model was established by treating the rat glioblastoma cell line C6 with MPP⁺. SIP was overexpressed in C6 cells using SIP-plasmid. Cell viability and apoptosis were analyzed using MTT assay and flow cytometer respectively. Tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels were detected using enzyme linked immunosorbent assay and quantitative reverse transcription PCR. Besides, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production, and superoxide dismutase (SOD) enzyme activity were determined in the present study. For protein and mRNA detection, western blot assay, and qRT-PCR were performed respectively.

Results

SIP was decreased in MPP⁺-induced C6 cells. SIP overexpression relieved MPP⁺-induced cytotoxicity of C6 cells, displayed as increased cell viability and reduced cell apoptosis and reduced LDH release. Besides, SIP inhibited MPP⁺-induced inflammatory response and oxidative stress, evidenced by decreased levels of inflammatory factors (TNF-α and IL-1β), reduced ROS generation and enhanced SOD activity. Moreover, MPP⁺-induced nuclear factor-κB activation was inhibited by SIP overexpression.

Conclusions

SIP was downregulated in Parkinson’s disease and it played a protective role in the development Parkinson’s disease, thus may be a promising target for Parkinson’s disease treatment.

Tectorigenin attenuates the MPP+-induced SH-SY5Y cell damage, indicating a potential beneficial role in Parkinson's disease by oxidative stress inhibition

Tectorigenin is a plant isoflavonoid primarily derived from the flowers of Pueraria thomsonii Benth. Although various biological properties of tectorigenin have been reported, such as its antioxidant activity, the effects of tectorigenin on the cellular models of Parkinson's disease have not yet been elucidated. The aims of the current study were to investigate whether tectorigenin prevents neurotoxicity induced by MPP⁺ (also known as 1-methyl-4-phenylpyridinium) in SH-SY5Y cells and to elucidate the underlying protective mechanism. Cell viability and lactate dehydrogenase release were measured. The morphological changes of apoptotic cells were observed by Hoechst 33258 staining. Caspase-3, superoxide dismutase, catalase and glutathione peroxidase activity was measured using commercially available ELISA kits. The expression of cytochrome c, Bax, Bcl-2 and NADPH oxidase were detected by western blot analysis. The results indicated that treatment with MPP⁺ causes a significant decrease in the viability of cells and an increase in apoptosis, as evidenced by the upregulation of apoptotic cells, caspase-3 activity and cytochrome c expression. By contrast, these effects were all reversed by pretreatment with tectorigenin in SH-SY5Y cells. Tectorigenin also inhibited the MPP⁺-induced changes of Bax and Bcl-2 levels. In addition, pretreatment with tectorigenin mitigated the MPP⁺-caused increases in the levels of reactive oxygen species and NADPH oxidase protein in SH-SY5Y cells. Simultaneously, tectorigenin abolished the downregulation of antioxidant enzymes, including superoxide dismutase, catalase and glutathione peroxidase, that was induced by MPP⁺. In conclusion, the present study data indicate that the neuroprotective effect of tectorigenin against MPP⁺-induced cytotoxicity and apoptosis may be involved in attenuating oxidative stress and enhancing antioxidant defense.

Atp13a2 Deficiency Aggravates Astrocyte-Mediated Neuroinflammation via NLRP3 Inflammasome Activation

AIM

Atp13a2 (Park9) gene encodes a transmembrane lysosomal P5-type ATPase (ATP13A2), and its missense or truncation mutations leads to lysosomal dysfunction and consequently results in neuronal death in the pathogenesis of Parkinson's disease (PD). Nevertheless, the roles of ATP13A2 in the biological features of astrocytes, especially in the regulation of PD-related neuroinflammation, have not been investigated.

METHODS

We cultured primary neurons and astrocytes from mouse midbrain to investigate the mechanisms for astrocyte ATP13A2-regulated lysosomal function and neuroinflammation following 1-methyl-4-phenylpyridinium (MPP(+) ) treatment.

RESULTS

We found that astrocytes expressed considerable levels of ATP13A2 and deficiency of ATP13A2 in astrocyte-induced intense inflammation, which exacerbated dopaminergic neuron damage after exposure to MPP(+) . Notably, lack of ATP13A2 increased lysosomal membrane permeabilization and cathepsin B release, which in turn exacerbated activation of nod-like receptor protein 3 (NLRP3) inflammasome to produce excess IL-1β from astrocytes. Furthermore, overexpression of ATP13A2 reversed MPP(+) -induced cathepsin B release and NLRP3 inflammasome activation in astrocytes.

CONCLUSIONS

Our results have revealed a novel role of ATP13A2 in modulating astrocyte-mediated neuroinflammation via NLRP3 inflammasome activation, thus bringing to light of a direct link between astrocyte lysosome and neuroinflammation in the pathological model of PD.