Effects of β-amyloid on the Expression of Forkhead Protein O3a and Postsynaptic Density Protein 95
10.13471/j.cnki.j.sun.yat-sen.univ(med.sci).2021.0505
- VernacularTitle:β-淀粉样蛋白对叉头蛋白O3a和突触后致密蛋白95的影响
- Author:
Bo NIU
1
;
Xin-yi WANG
1
;
Jiang-ping XU
1
;
Hai-tao WANG
1
Author Information
1. Department of Neuropharmacology， School of Pharmaceutical Sciences， Southern Medical University， Guangzhou 510515， China
- Publication Type:Journal Article
- Keywords:
β-amyloid;
fork box protein O3a;
postsynaptic dense protein 95;
protein kinase B;
Alzheimer's disease
- From:
Journal of Sun Yat-sen University(Medical Sciences)
2021;42(5):676-685
- CountryChina
- Language:Chinese
-
Abstract:
ObjectiveTo understand the mechanism of β-amyloid （Aβ）-induced neurotoxicity， this study aimed to investigate the effects and possible pathways of Aβ on apoptosis-related nuclear transcription forkhead protein O3a （FoxO3a） and postsynaptic density protein 95 （PSD95）. MethodsPC12 cells and neurons were treated with gradient concentrations （5， 10， 20 μmol/L） of Aβ25-35 for 24 h， and the alterations of FoxO3a and PSD95 were detected by RT-PCR and Western blot. Immunofluorescence assay was used to detect the level of PSD95 in PC12 cells and the subcellular localization of FoxO3a in the cells. Then in rats injected with Aβ25-35 and APP/PS1 transgenic mice， the changes of PSD95 and FoxO3a in brain tissue were investigated. Western Blot was used to detect the effects of Aβ on the phosphorylation of FoxO3a and protein kinase B （AKT） in vitro and in vivo. ResultsCompared with cells in the normal control group， the protein levels of PSD95 in the cells treated with Aβ25-35 at the dosage of 20 μmol/L were down-regulated to （45.09±1.61）% （P=0.054 0）. Correspondingly， the protein levels of FoxO3a were increased to （228.70±20.44）% （F=17.48， P=0.021 0） when the cells were treated with 20 μmol/L of Aβ25-35. In the primary cultured neurons， similar results were obtained. In addition， the results of immunofluorescence showed that Aβ25-35 promoted the nuclear translocation of FoxO3a. The residence time of Aβ25-35-injected group was （24.35 ±1.29） s （F=2.843， P=0.098） and the number of crossings was 2.53±0.49 （F=3.459， P=0.014 9） of rats in the water maze test. There was significant difference between the CTL group and Aβ25-35-injected group （P<0.05）. The RT-PCR assay showed that the mRNA level of PSD95 in the hippocampus of rats treated with Aβ25-35 was decreased to （58.40±8.28）% （F=1.193， P=0.010 1） of that in the CTL group， and the mRNA expression of FoxO3a was increased to （140.90±7.45）% （F=2.378， P=0.049 6）. In the brain tissue of 7-month-old APP/PS1 transgenic mice， the mRNA and protein levels of PSD95 were down-regulated to （60.89 ±1.53）% （F=20.05， P=0.008 8） and （59.63±13.55）% （F=8.496， P=0.044 5）. Meanwhile the mRNA and protein levels of FoxO3a were up-regulated to （172.4±4.87）% （F=2.351， P=0.000 4） and （235.00 ± 39.03）% （F=2.754， P=0.032 0）， respectively. After treatment with 20 μmol/L Aβ25-35 for different times （5， 10， 20， 40 min）， the phosphorylation of FoxO3a and AKT in PC12 cells was decreased with time. The levels of phosphorylated AKT and FoxO3a in the brain tissue of APP/PS1 transgenic mice were decreased to （65.75±3.51）% （F=6.362， P=0.023 6） and （46.62 ± 9.64）% （F=8.562， P=0.007 9） when compared with mice in the control group. ConclusionsAβ can up-regulate the expression of nuclear transcription FoxO3a and down-regulate the change of PSD95 in both in vitro cell models and in vivo animal models. The possible mechanism is to reduce the phosphorylation level of FoxO3a and increase the expression of FoxO3a by dephosphorylating AKT.
