Objective To investigate the effect of very-long-chain saturated fatty acids on Tau protein phosphorylation and membrane fluidity in human neuroblastoma SH-SY5Y cells,and to explore its role in the pathogenesis of Alzheimer's disease(AD).Methods Human neuroblastoma SH-SY5Y cells in logarithmic growth phase were randomly divided into control group,C22∶0 group,and C24:0 group.Cells in the control group were routinely cultured,while cells in the C22:0 and C24:0 groups were treated with culture medium containing 10 μmol·L-1very-long-chain saturated fatty acids C22:0 and C24:0,respectively.After 24 hours of incubation,cells were collected.The expression levels of total Tau protein,phosphorylated Tau protein at serine 396 site(p-Tau-ser396),glycogen synthase kinase 3β(GSK-3β),and phosphorylated GSK-3 β protein at serine 9 site(p-GSK-3β-Ser9)in cells of each group were detected by using Western blot.The malondialdehyde(MDA)level in cells of each group was determined by using the thiobarbituric acid method.The fluorescence recovery rate and diffusion coefficient of cell membranes were measured by using fluorescence recovery after photobleaching technique,and the fluidity of cell membranes was evaluated.Results The total Tau protein level in SH-SY5Y cells showed no statistically significant difference among the three groups(F=1.807,P＞0.05).However,there was a statistically significant difference in the level of p-Tau-ser396 in SH-SY5Y cells among the three groups(F=18.397,P＜0.05).Specifically,the level of p-Tau-ser396 in SH-SY5Y cells in the C22:0 and C24:0 groups was significantly higher than that in the control group(P＜0.05),and the level of p-Tau-ser396 in SH-SY5Y cells in the C24:0 group was significantly higher than that in the C22:0 group(P＜0.05).There was no statistically significant difference in the GSK-3 β protein level in SH-SY5Y cells among the three groups(F=0.351,P＞0.05).However,there was a statistically significant difference in the level of p-GSK-3β-Ser9 in SH-SY5Y cells among the three groups(F=13.330,P＜0.05).Specifically,the level of p-GSK-3β-ser9 in SH-SY5Y cells in the C22:0 and C24:0 groups was significantly lower than that in the control group(P＜0.05),and there was no statistically significant difference in the level of p-GSK-3β-ser9 in SH-SY5Y cells between the C22:0 group and C24:0 group(P＞0.05).The MDA level in SH-SY5Y cells in the C24:0 group was significantly higher than that in the control group and C22:0 group(P＜0.05);there was no statistically significant difference in the MDA level in SH-SY5Y cells between the control group and C22:0 group(P＞0.05).The fluorescence recovery rate and diffusion coefficient of SH-SY5Y cells in the C22:0 and C24:0 groups showed a decreasing trend compared to the control group,but there was no statistically significant difference in the fluorescence recovery rate and diffusion coefficient of SH-SY5Y cells among the three groups(F=3.891,3.649,P＞0.05).Conclusion Very-long-chain saturated fatty acids C22:0 and C24:0 can promote hyperphosphorylation of Tau protein,induce cellular oxidative damage,and tend to reduce the fluidity cell membranes.Very-long-chain saturated fatty acids may be one of the factors that cause the onset of AD.
very-long-chain saturated fatty acidsAlzheimer's diseaseTau protein phosphorylationmembrane fluidity
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