Astaxanthin Suppresses MPP~+-induced Oxidative Damage In PC12Cells Through A Sp1/NR1Signaling Pathway

Background: PD is a high incidence of neurodegenerative diseases in elderlypeople, and oxidatie stress plays an important role in PD pathogenesis mechanism.Brain is a high oxygen metabolism rate tissue, and lack of antioxidant protectionmechanism. Sp1is a member of the Sp family of transcription factors that bind at GCboxes to regulate gene expression.Sp1is usually an activator of transcription, upregulating downstream geneexpression, and controlling cell growth and apoptosis. It is linked to the occurrenceand progression of many diseases, including autoimmune disorder and malignanttumor. N-Methyl-D-aspartate (NMDA) receptors mediate fast excitatory synaptictransmission in the central nervous system and play a major role in neuronal processessuch as synaptic plasticity, learning and memory. Overactivation of NMDA receptorscan lead to neuronal degeneration thought to underlie various neurodegenerativedisorders. The formation of functional NMDA receptors (NMDARs) requires anessential subunit NR1. During oxidative stress, Sp1is upregulated, havingdownstream effects on NMDA receptor subunit expression. Antioxidants couldattenuate the expression of Sp1and NR1. Maybe, Sp1/NR1is importmant in PD.In recent years, it found that astaxanthin plays an an important role inantioxidation、antiradical and antiapoptotic, and can through the blood brain barriersmoothly. Sp1/NR1cell signaling pathways was not been reported in PC12cells.Therefore, to research the mechanism of ATX protect PC12cell damage by MPP~+will provide a new idea to protect and treatment of PD.Objective：To investigate astaxanthin(ATX) neuroprotection, and its mechanism, ona1-methyl-4-phenyl-pyridine ion (MPP~+)-induced cell model of Parkinson’sdisease.Methods: Mature, differentiated PC12cells treated with MPP~+were used as an invitro cell model. The MTT assay was used to investigate cell viability after ATX treatment, and western blot analysis was used to observe Sp1and NR1proteinexpression, real-time PCR was used to monitor Sp1and NR1mRNA，and cellimmunofluorescence was used to determine the location of Sp1and NR1protein andthe nuclear translocation of Sp1.Results: PC12cell viability was significantly reduced by MPP~+treatment. Theexpression of Sp1and NR1mRNA and protein were increased, compared with thecontrol (P<0.01). Following cotreatment with ATX and MPP~+, cell viability wassignificantly increased, and Sp1and NR1mRNA and protein were decreased,compared with the MPP~+groups (P<0.01). In addition，mithracycin A protected PC12cells from oxidative stress caused by MPP~+by specifically inhibiting the expressionof Sp1. Moreover, cell immunofluorescence revealed that Sp1expressed in both thecytoplam and nuclei of PC12cells, whereas NR1was expressed only in theendochylema.Conclusion: ATX inhibited oxidative stress induced by MPP~+in PC12cells, via theSP1/NR1signaling pathway. And MIT could protect PC12cells in some degree.