Objective To study the effects of TYRO protein kinase-binding protein (TYROBP) deficiency on learning behavior, glia activation and pro-inflammatory cycokines, and Tau phosphorylation of a new Alzheimer's disease (AD) mouse model carrying a PSEN1 p.G378E mutation.Methods A new AD mouse model carrying PSEN1 p.G378E mutation was built based on our previously found AD family which might be ascribed to the PSEN1 mutation, and then crossed with TYROBP deficient mice to produce the heterozygous hybrid mice (PSEN1^G378E/WT; Tyrobp^+/-) and the homozygous hybrid mice (PSEN1^G378E/G378E; Tyrobp^-/-). Water maze test was used to detect spatial learning and memory ability of mice. After the mice were sacrificed, the hippocampus was excised for further analysis. Immunofluorescence was used to identify the cell that expresses TYROBP and the number of microglia and astrocyte. Western blot was used to detect the expression levels of Tau and phosphorylated Tau (p-Tau), and ELISA to measure the levels of pro-inflammatory cytokines. Results Our results showed that TYROBP specifically expressed in the microglia of mouse hippocampus. Absence of TYROBP in PSEN1^G378E mutation mouse model prevented the deterioration of learning behavior, decreased the numbers of microglia and astrocytes, and the levels of interleukin-6, interleukin-1β and tumor necrosis factor-α in the hippocampus (all P < 0.05). The ratios of AT8/Tau5, PHF1/Tau5, pT181/Tau5, pT231/Tau5 and p-ERK/ERK were all higher in homozygous hybrid mice (PSEN1^G378E/G378E; Tyrobp^-/- mice) compared with PSEN1^G378E/G378E mice (all P < 0.05). Conclusions TYROBP deficiency might play a protective role in the modulation of neuroinflammation of AD. However, the relationship between neuroinflammation processes involving microglia and astrocyte activation, and release of pro-inflammatory cytokines, and p-Tau pathology needs further study.
Mice ; Animals ; Alzheimer Disease/genetics* ; Neuroinflammatory Diseases ; Hippocampus/pathology* ; Mutation ; Cytokines/pharmacology* ; Disease Models, Animal ; tau Proteins/pharmacology* ; Amyloid beta-Peptides/metabolism* ; Adaptor Proteins, Signal Transducing/pharmacology*

Alzheimer's disease (AD) is the most common form of dementia among the elderly, characterized by amyloid plaques, neurofibrillary tangles, and neuroinflammation in the brain, as well as impaired cognitive behaviors. A sex difference in the prevalence of AD has been noted, while sex differences in the cerebral pathology and relevant molecular mechanisms are not well clarified. In the present study, we systematically investigated the sex differences in pathological characteristics and cognitive behavior in 12-month-old male and female APP/PS1/tau triple-transgenic AD mice (3×Tg-AD mice) and examined the molecular mechanisms. We found that female 3×Tg-AD mice displayed more prominent amyloid plaques, neurofibrillary tangles, neuroinflammation, and spatial cognitive deficits than male 3×Tg-AD mice. Furthermore, the expression levels of hippocampal protein kinase A-cAMP response element-binding protein (PKA-CREB) and p38-mitogen-activated protein kinases (MAPK) also showed sex difference in the AD mice, with a significant increase in the levels of p-PKA/p-CREB and a decrease in the p-p38 in female, but not male, 3×Tg-AD mice. We suggest that an estrogen deficiency-induced PKA-CREB-MAPK signaling disorder in 12-month-old female 3×Tg-AD mice might be involved in the serious pathological and cognitive damage in these mice. Therefore, sex differences should be taken into account in investigating AD biomarkers and related target molecules, and estrogen supplementation or PKA-CREB-MAPK stabilization could be beneficial in relieving the pathological damage in AD and improving the cognitive behavior of reproductively-senescent females.
Alzheimer Disease ; metabolism ; pathology ; psychology ; Amyloid beta-Protein Precursor ; genetics ; metabolism ; Animals ; Cyclic AMP Response Element-Binding Protein ; metabolism ; Cyclic AMP-Dependent Protein Kinases ; metabolism ; Disease Models, Animal ; Female ; Hippocampus ; metabolism ; pathology ; Humans ; Inflammation ; metabolism ; pathology ; psychology ; Male ; Maze Learning ; physiology ; Mice, Inbred C57BL ; Mice, Transgenic ; Neurofibrillary Tangles ; metabolism ; pathology ; Plaque, Amyloid ; metabolism ; pathology ; psychology ; Presenilin-1 ; genetics ; metabolism ; Sex Characteristics ; Spatial Memory ; physiology ; p38 Mitogen-Activated Protein Kinases ; metabolism ; tau Proteins ; genetics ; metabolism

OBJECTIVETo explore the relations among apolipoprotein E4, Tau protein and glycogen synthase kinase 3β (GSK-3β).

METHODSU87 cells were transfected with pIRES-EGFP (control) or the recombinant plasmids ApoE4/pIRES-EGFP or ApoE3/pIRES-EGFP, and the expression levels of p-Tau/Tau and GSK-3β in the cells were examined with Western blotting. To further confirm the effect of ApoE on GSK-3β and p-Tau expressions, a short interfering RNA (siRNA) targeting ApoE (ApoE-siRNA) was transfected into U87 cells via Lipofectamine 2000 and the protein expressions were examined 24 h later.

RESULTSCompared with those in the control group, the expressions levels of both GSK-3β and p-Tau/Tau increased significantly in the cells transfected with ApoE4 and ApoE3 plasmids (P<0.01), and the ApoE4 plasmid produced a more potent effect than the ApoE3 plasmid on the protein expressions (P<0.01). ApoE knockdown resulted in significantly reduced expressions of GSK-3β (P<0.001) and p-Tau (P<0.01) in the cells.

CONCLUSIONApoE4 can enhance Tau phosphorylation though upregulating GSK-3β, which sheds light on a new role of ApoE4 in Alzheimer's disease.

Alzheimer Disease ; genetics ; Apolipoprotein E3 ; genetics ; Apolipoprotein E4 ; genetics ; Cell Line ; Gene Silencing ; Glycogen Synthase Kinase 3 beta ; genetics ; metabolism ; Humans ; Phosphorylation ; RNA, Small Interfering ; genetics ; Transfection ; tau Proteins ; metabolism

Mammalian cells remove misfolded proteins using various proteolytic systems, including the ubiquitin (Ub)-proteasome system (UPS), chaperone mediated autophagy (CMA) and macroautophagy. The majority of misfolded proteins are degraded by the UPS, in which Ub-conjugated substrates are deubiquitinated, unfolded and cleaved into small peptides when passing through the narrow chamber of the proteasome. The substrates that expose a specific degradation signal, the KFERQ sequence motif, can be delivered to and degraded in lysosomes via the CMA. Aggregation-prone substrates resistant to both the UPS and the CMA can be degraded by macroautophagy, in which cargoes are segregated into autophagosomes before degradation by lysosomal hydrolases. Although most misfolded and aggregated proteins in the human proteome can be degraded by cellular protein quality control, some native and mutant proteins prone to aggregation into beta-sheet-enriched oligomers are resistant to all known proteolytic pathways and can thus grow into inclusion bodies or extracellular plaques. The accumulation of protease-resistant misfolded and aggregated proteins is a common mechanism underlying protein misfolding disorders, including neurodegenerative diseases such as Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD), prion diseases and Amyotrophic Lateral Sclerosis (ALS). In this review, we provide an overview of the proteolytic pathways in neurons, with an emphasis on the UPS, CMA and macroautophagy, and discuss the role of protein quality control in the degradation of pathogenic proteins in neurodegenerative diseases. Additionally, we examine existing putative therapeutic strategies to efficiently remove cytotoxic proteins from degenerating neurons.
Alzheimer Disease/drug therapy/metabolism ; Amyloid beta-Peptides/metabolism ; Amyotrophic Lateral Sclerosis/drug therapy/metabolism ; Animals ; Autophagy/drug effects ; DNA-Binding Proteins/metabolism ; Humans ; Huntington Disease/drug therapy/genetics/metabolism ; Lysosomes/metabolism ; Molecular Targeted Therapy ; Mutation ; Nerve Tissue Proteins/genetics/metabolism ; Neurodegenerative Diseases/drug therapy/*metabolism ; Parkinson Disease/drug therapy/metabolism ; PrPSc Proteins/metabolism ; Prion Diseases/drug therapy/metabolism ; Proteasome Endopeptidase Complex/metabolism ; Proteolysis ; Proteostasis Deficiencies/metabolism ; Superoxide Dismutase/metabolism ; Ubiquitin/metabolism ; alpha-Synuclein/metabolism ; tau Proteins/metabolism

The receptor for advanced glycation end products (RAGE) has been reported to have a pivotal role in the pathogenesis of Alzheimer's disease (AD). This study investigated RAGE levels in the hippocampus and cortex of a triple transgenic mouse model of AD (3xTg-AD) using western blotting and immunohistochemical double-labeling to assess cellular localization. Analysis of western blots showed that there were no differences in the hippocampal and cortical RAGE levels in 10-month-old adult 3xTg-AD mice, but significant increases in RAGE expression were found in the 22- to 24-month-old aged 3xTg-AD mice compared with those of age-matched controls. RAGE-positive immunoreactivity was observed primarily in neurons of aged 3xTg-AD mice with very little labeling in non-neuronal cells, with the notable exception of RAGE presence in astrocytes in the hippocampal area CA1. In addition, RAGE signals were co-localized with the intracellular amyloid precursor protein (APP)/amyloid beta (Abeta) but not with the extracellular APP/Abeta. In aged 3xTg-AD mice, expression of human tau was observed in the hippocampal area CA1 and co-localized with RAGE signals. The increased presence of RAGE in the 3xTg-AD animal model showing critical aspects of AD neuropathology indicates that RAGE may contribute to cellular dysfunction in the AD brain.
Advanced Glycosylation End Product-Specific Receptor ; Alzheimer Disease/genetics/*metabolism ; Amyloid beta-Peptides/metabolism ; Animals ; Astrocytes/*metabolism ; CA1 Region, Hippocampal/growth & development/metabolism/pathology ; Humans ; Mice ; Mice, Transgenic ; Neurons/*metabolism ; Receptors, Immunologic/genetics/*metabolism ; tau Proteins/genetics/metabolism

Alzheimer disease (AD) is a common neurodegenerative disease. Drosophila has been regard as one of the ideal models for Alzheimer because of its unique advantage on genetic manipulation. AD transgenic drosophila models not only help to elucidate the pathogenesis of Alzheimer disease, but also provide potential screening models for drugs to treat the disease. In this review, we summarize the recent research progress using AD transgenic drosophila.
Alzheimer Disease ; etiology ; genetics ; metabolism ; Amyloid beta-Peptides ; metabolism ; Animals ; Animals, Genetically Modified ; genetics ; Disease Models, Animal ; Drosophila ; genetics ; Drug Evaluation, Preclinical ; Gene Transfer Techniques ; Humans ; Phosphorylation ; tau Proteins ; metabolism

OBJECTIVETo construct a prokaryotic expression vector of human tau multiepitope peptide for examining the immunogenicity of a TauP1/P2 DNA vaccine in mice using the expressed product.

METHODSThe coding sequence of Tau multiepitope peptide gene was amplified from the plasmid pVAX1-Tau by PCR and inserted into the prokaryotic expression vector pGEX-4T-2 to construct the recombinant plasmid pGEX-4T-2-TauP1/P2. The positive recombinants were transformed into E.coli BL21 cells, and the expression of fusion protein GST-TauP1/P2 was induced by IPTG and identified by SDS-PAGE. Mice was immunized with TauP1/P2 DNA vaccine and the production of the specific antibodies was detected by Dot-blot analysis using the purified fusion protein.

RESULTSA gene fragment 300 bp in length was amplified. Enzyme digestion and DNA sequencing verified correct construction of the prokaryotic expression plasmid pGEX-4T-2-TauP1/P2. The expression of target fusion protein GST-TauP1/P2 was detected by SDS-PAGE. Specific antibodies against TauP1/P2 were detected in the serum of mice immunized with the DNA vaccine using GST-TauP1/P2 fusion protein.

CONCLUSIONThe constructed prokaryotic expression plasmid of human Tau multiepitope peptide is capable of expressing the target fusion protein, which specifically recognizes the specific antibodies against TauP1/P2 in mice immunized with TauP1/P2 DNA vaccine.

Animals ; Epitopes ; immunology ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Humans ; Mice ; Mice, Inbred C57BL ; Peptides ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Vaccines, DNA ; biosynthesis ; immunology ; tau Proteins ; biosynthesis ; genetics ; immunology

BACKGROUNDNeuropathologically, Alzheimer disease (AD) is characterized by the presence of extracellular plaques enriched in beta-amyloid peptides; however, the mechanism by which it results in the neurotoxicity is uncertain. The purpose of this study was to investigate whether it would prompt the progress of Alzheimer disease via enhancement of aberrant phosphorylated tau that results from its increased kinase gene expression.

METHODSTwenty-four male rats were divided into three groups, and each group had 8 rats: control, sham-operated, and Abeta(25-35) injected AD model groups. AD rat models were created by unilateral injections of Abeta(25-35) into the amygdala. The hyperphosphorylated tau protein was estimated by immunohistochemistry with paired helical filament-1 (PHF-1) antibody and paired helical filament-tau (AT8) antibody. The expressions of glycogen synthase kinase-3beta (GSK-3beta) and p38 mitogen-activated protein kinase (P(38)MAPK) mRNA were observed by in situ hybridization.

RESULTSCompared with the control and sham-operated groups, the evaluation of paired AT8 and paired helical filament-1 (PHF-1) in the cortexes and hippocampus of the AD model group showed the numbers of AT8 and PHF-1 positive cells, as well as the optical density (OD) values of the proteins were significantly higher (AT8: in CA2: 0.318 +/- 0.037 vs. 0.135 +/- 0.028, 0.136 +/- 0.031; in frontal cortex: 0.278 +/- 0.040 vs. 0.130 +/- 0.028, 0.190 +/- 0.037. PHF-1: in CA2: 0.386 +/- 0.034 vs. 0.139 +/- 0.010, 0.193 +/- 0.041; in frontal cortex: 0.395 +/- 0.050 vs. 0.159 +/- 0.030, 0.190 +/- 0.044, respectively, P < 0.01); the number of GSK-3beta mRNA and P(38)MAPK mRNA positive cells of the AD model group, as well as the OD values, also increased significantly in the cortexes, hippocampus (GSK-3beta-mRNA: in CA2: 0.384 +/- 0.012 vs. 0.190 +/- 0.015, 0.258 +/- 0.064; in frontal cortex: 0.398 +/- 0.018 vs. 0.184 +/- 0.031, 0.218 +/- 0.049. P(38)MAPK mRNA: in CA2: 0.409 +/- 0.038 vs. 0.161 +/- 0.041, 0.189 +/- 0.035; in frontal cortex: 0.423 +/- 0.070 vs. 0.160 +/- 0.032, 0.203 +/- 0.053, respectively, P < 0.01).

CONCLUSIONUnilateral injection of Abeta(25-35) into the rat amygdala increases the generation of aberrant phosphorylated tau by increasing GSK-3beta and P(38)MAPK gene expression, that accelerates the process of Alzhemer's disease.

Amygdala ; drug effects ; metabolism ; Amyloid beta-Peptides ; pharmacology ; Animals ; Antibodies, Monoclonal ; metabolism ; Glycogen Synthase Kinase 3 ; genetics ; Glycogen Synthase Kinase 3 beta ; Immunohistochemistry ; In Situ Hybridization ; Male ; Peptide Fragments ; pharmacology ; Phosphorylation ; drug effects ; Rats ; Rats, Sprague-Dawley ; p38 Mitogen-Activated Protein Kinases ; genetics ; tau Proteins ; metabolism

OBJECTIVETo study the effect of Panax notoginseng saponins (PNS) on (synaptophysin, syp) and tau gene expression in the brain tissue in senescence accelerated mouse prone 8 (SAMP 8).

METHODSAMP8 were randomly divided into 4 groups: PNS 23.38, 93.50 mg x kg(-1) group, huperzin A 0.038 6 mg x kg(-1) x d(-1) group and blank control group; the drug groups were treated with the designed drugs respectively per day by intragastric administration for 4 consecutive weeks, and double distilled water was given to blank control group. After treatment, the mRNA content of tau and syp were assayed by reverse transcription (RT) and real-time polymerase chain reaction (real-time PCR).

RESULTCompared with blank control group, the syp mRNA contents were increased in PNS groups (P < 0.05 or P < 0.01), and the tau mRNA content were not significant difference in all groups.

CONCLUSIONThis study suggests that PNS can up-regulate syp gene expression at transcriptional level in the brain of SAMP 8.

Aging ; drug effects ; metabolism ; Animals ; Brain ; drug effects ; metabolism ; Gene Expression ; drug effects ; genetics ; Mice ; Panax notoginseng ; chemistry ; Protein Tyrosine Phosphatase, Non-Receptor Type 11 ; genetics ; metabolism ; Saponins ; pharmacology ; tau Proteins ; genetics ; metabolism

Alzheimer Disease ; genetics ; metabolism ; therapy ; Humans ; tau Proteins ; genetics ; metabolism