IntroductionPresenilin-1 (PS1) is a macromolecular protein found on the endoplasmic reticulum and Golgi apparatus. It is a transmembrane protein, which can form a complex with APP in cells and participate in the transport and post-synthesis processing of APP. Human-type progerin1,2 has anti-apoptotic effects, while mutant progerin-1 is easily cleaved by caspases and can increase amyloid in neurons.
Presenilin-1 (PS-1) is a macromolecular protein on the endoplasmic reticulum and Golgi apparatus, consisting of 467 amino acid residues, and the chromosomal localization of its gene is 14q243。Progerin-1 in the human brain increases with age, affecting the memory of older adults. Mutations in the PS-1 gene, which encodes the protein, are thought to be closely related to the pathogenesis of Alzheimer's disease.
Biological structure
Progerin-1 is composed of 467 amino acid residues, and its gene is chromosomely localized at 14q24 3。
There are genetic polymorphisms in the PS1 gene, and 2 alleles are common. Allele 1 is a at the 3rd end of its exon 8, intron 16 is A, and allele 2 is C.
If PCR (polymerase chain reaction) is performed with appropriate primers, the PS1 PCR product is cleaved with the restriction enzyme BamH1. The product of allele 1 can be cleaved at that site, while the product of allele 2 is not, which can be distinguished. The incidence of AD is higher in the 1 1 genotype than in the 1 2 or 2 2 genotype.
Research
Effect of Presenilin-1 (PS1) overexpression on tau phosphorylation: Different PS1 plasmids were transfected on NC-108 cells, and the effects of overexpression of presenilin-1 on tau phosphorylation were observed by immunodouble standard, immunoblotting, immunocytochemistry, MTT, Western blot and other methods.
ResultsThe immuno-labeling showed that ps1 was mainly distributed in neurons and coexisted with phosphorylated tau protein in the brains of patients with sporadic AD. Western blotting showed that phosphorylated tau protein was increased in NG-108 cells transfected with wild-type PS1 group and familial Familial Alzheimer Disease (FAD)-mutant progerin-1 (MPS1) plasmid group compared with the empty plasmid group. The MTT method did not detect a significant difference between the transfected cells in these two groups and the control group.
The transfection group of PS1-EGFP plasmid was observed by confocal microscopy, and it was found that PS1-EGFP was mainly distributed on the surface of the cell membrane or organelles in the early 12 h after transfection, and then PS1-EGFP was mainly diffusely distributed in the cytoplasm.
At the same time, immunocytochemistry showed that there was obvious phosphorylation of tau protein in some ps1-egfp-transfected cells, and these phosphorylated tau proteins could form aggregates with ps1-egfp protein. After administration of the phosphatase inhibitor gangtanic acid, PS1-EGFP-transfected cells contained more phosphorylated tau protein than untransfected cells. ConclusionsWild-type PS1 may be involved in the pathological changes of tau protein in sporadic Alzheimer's disease.