OBJECTIVESTo investigate the neuroprotective function of alpha7 nicotinic receptor (nAChR) and its roles in the pathogenesis of Alzheimer's disease (AD).

METHODSpecific RNA interference to alpha7 nAChR mRNA expression was performed by gene specific small interference RNA (siRNA). SH-SY5Y cells were transfected with the siRNA or treated with 20 micromol/L 3-[2, 4-dimethoxybenzylidene] anabaseine (DMXB), an alpha7 nAChR agonist. After 48 hrs culture, levels of alpha7 nAChR mRNA and protein were monitored by RT-PCR and Western blotting, respectively. In the second experiment, SH-SYSY cells treated with siRNA or DMXB were exposed to 1 micromol/L Abeta(25-35), followed by protein analysis of alpha-form of secreted beta-amyloid precursor peptide (alphaAPPs), and total APP was assayed by Western blotting. In addition, lipid peroxidation and MTT [3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] reduction were measured by spectrophotometry.

RESULTIn RNA interference group, as compared with controls, alpha7 nAChR mRNA and protein levels were decreased with inhibitory efficiency by 80% and 69%, respectively, along with a decrease in protein levels of alphaAPP and reduction of MTT. However the product of lipid peroxidation was increased. There was an enhanced gene inhibition of alpha7 nAChR by Abeta. While cells treated with DMXB, the alpha7 nAChR protein was increased by 23% as compared with that of the control, along with decrease of alphaAPP and ERK 1/2 at the protein level. The enhanced expression of alpha7 nAChR reduced the neurotoxic effects resulted from Abeta.

CONCLUSIONThe findings indicate that alpha7 nAChR may play a significant neuroprotective role by enhancing cleavage of APP, improving antioxidant defenses and limiting the toxicity of Abeta, which has been implied in the pathogenesis of AD.

Acetylcholine ; pharmacology ; Alzheimer Disease ; pathology ; physiopathology ; Amyloid beta-Peptides ; metabolism ; toxicity ; Amyloid beta-Protein Precursor ; pharmacology ; Cells, Cultured ; Humans ; Lipid Peroxidation ; Neurons ; drug effects ; pathology ; Neuroprotective Agents ; pharmacology ; Nicotinic Agonists ; pharmacology ; Protease Nexins ; RNA Interference ; RNA, Messenger ; drug effects ; metabolism ; RNA, Small Interfering ; pharmacology ; Receptors, Cell Surface ; Receptors, Nicotinic ; metabolism ; physiology ; alpha7 Nicotinic Acetylcholine Receptor

OBJECTIVETo investigate the genetic polymorphisms of rs2229338 and rs12218 loci of serum amyloid protein A1 (SAA1) gene in healthy Chinese Han and Uighur populations of Xinjiang.

METHODSThe genotypes of the SAA1 gene were detected in 316 Uighur and 362 Han healthy individuals by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).

RESULTSThe genotype distributions of both populations were in the Hardy-Weinberg equilibrium (both P>0.05). The frequencies of AA, AG and GG genotypes of the rs2229338 locus were 76.6%, 23.4%, and 0 in the Uighurs, and 91.7%, 7.7% and 0.6% in the Hans. There was significant difference in distribution of genotypes between the two populations (P<0.01). The frequencies of CC, CT and TT genotypes of the rs12218 locus were 10.1%, 47.5%, and 42.4% in Uighurs, and 3.3%, 34.3% and 62.4% in Hans. There was also significant difference in distribution of genotypes between the two populations (P<0.01). The A-C and G-T haplotypes were more frequent in the Uighur but the A-T haplotype was more common in the Han population, respectively (both P<0.01).

CONCLUSIONThe mutational frequencies of the tagging SNPs in rs2229338 and rs12218 loci of theSAA1 gene in the Uighurs may be higher than those in Hans.

Alleles ; Amyloid ; genetics ; metabolism ; Asian Continental Ancestry Group ; genetics ; Ethnic Groups ; genetics ; Gene Frequency ; ethics ; Genotype ; Haplotypes ; ethics ; genetics ; Humans ; Polymorphism, Genetic ; Polymorphism, Restriction Fragment Length ; genetics ; Polymorphism, Single Nucleotide ; Protease Nexins ; genetics ; Serum Amyloid A Protein ; genetics

The multiple-step cleavage of amyloid precursor protein (APP) generates amyloid-β peptides (Aβ), highly toxic molecules causing Alzheimer's disease (AD). The nonspecific cleavage between the transmembrane region of APP (APPTM) and γ-secretase is the key step of Aβ generation. Reconstituting APPTM under physiologically-relevant conditions is crucial to investigate how it interacts with γ-secretase and for future AD drug discovery. Although producing recombinant APPTM was reported before, the large scale purification was hindered by the use of biological protease in the presence of membrane protein. Here, we expressed recombinant APPTM in Escherichia coli using the pMM-LR6 vector and recovered the fusion protein from inclusion bodies. By combining Ni-NTA chromatography, cyanogen bromide cleavage, and reverse phase high performance liquid chromatography (RP-HPLC), isotopically-labeled APPTM was obtained in high yield and high purity. The reconstitution of APPTM into dodecylphosphocholine (DPC) micelle generated mono dispersed 2D ¹⁵N-¹H HSQC spectra in high quality. We successfully established an efficient and reliable method for the expression, purification and reconstruction of APPTM, which may facilitate future investigation of APPTM and its complex in more native like membrane mimetics such as bicelle and nanodiscs.
Humans ; Amyloid beta-Protein Precursor/chemistry* ; Micelles ; Amyloid Precursor Protein Secretases/metabolism* ; Magnetic Resonance Spectroscopy ; Recombinant Proteins

Extracellular accumulation of amyloid beta protein (Abeta) plays a central role in Alzheimer's disease (AD). Some metals, such as copper, lead, and aluminum can affect the Abeta accumulation in the brain. However, the effect of mercury on Abeta accumulation in the brain is not clear. Thus, this study was proposed to estimate whether mercury concentration affects Abeta accumulation in PC12 cells. We treated 10, 100, and 1000 nM HgCl2 (Hg) or CH3HgCl2 (MeHg) for 48 hr in PC12 cells. After treatment, Abeta40 in culture medium increased in a dose- and time-dependent manner. Hg and MeHg increased amyloid precursor protein (APP), which is related to Abeta production. Neprilysin (NEP) levels in PC12 cells were decreased by Hg and MeHg treatment. These results suggested that Hg induced Abeta accumulation through APP overproduction and reduction of NEP.
Aluminum ; Alzheimer Disease ; Amyloid beta-Peptides ; Amyloid Precursor Protein Secretases ; Amyloid* ; Animals ; Brain ; Copper ; Mercuric Chloride ; Metals ; Neprilysin ; PC12 Cells*

Alzheimer's disease (AD) is characterized pathologically by cholinergic deficits, extracelluar amyloid deposit, intra-neuronal neurofibrillary tangles, gliosis and neuronal and synaptic loss. The primary therapeutic approach has been cholinergic augumentation by chlolinesterase inhibitors, which at best modestly improve cognitive function. Several recent advances have provided new insights and possibilities in defining therapeutic targets for AD. Research on the underlying pathophysiological dysfunction finally disclose more disease specific processes. Of particular importance is the identification and characterization of the secretases involved in endoproteolytic processing of beta-amyloid precursor protein, the precursor of the amyloid beta-peptide (A beta). It is generally accepted that A beta has pivotal role in the pathogenesis of AD, and that reducing brain A beta levels may be a disease modifying strategy. By inhibiting one or both amyloidogenic secretase and immunization with A beta, neuropathological features of AD can be prevented or alleviated.
Alzheimer Disease* ; Amyloid beta-Peptides ; Amyloid Precursor Protein Secretases ; Brain ; Gliosis ; Immunization ; Neurofibrillary Tangles ; Neurons ; Plaque, Amyloid ; Presenilins

Increased neuronal apoptosis is an important pathological feature of Alzheimer's disease (AD). The Bcl-2-interacting mediator of cell death (Bim) mediates amyloid-beta (Aβ)-induced neuronal apoptosis. Naturally-occurring antibodies against Bim (NAbs-Bim) exist in human blood, with their levels and functions unknown in AD. In this study, we found that circulating NAbs-Bim were decreased in AD patients. Plasma levels of NAbs-Bim were negatively associated with brain amyloid burden and positively associated with cognitive functions. Furthermore, NAbs-Bim purified from intravenous immunoglobulin rescued the behavioral deficits and ameliorated Aβ deposition, tau hyperphosphorylation, microgliosis, and neuronal apoptosis in APP/PS1 mice. In vitro investigations demonstrated that NAbs-Bim were neuroprotective against AD through neutralizing Bim-directed neuronal apoptosis and the amyloidogenic processing of amyloid precursor protein. These findings indicate that the decrease of NAbs-Bim might contribute to the pathogenesis of AD and immunotherapies targeting Bim hold promise for the treatment of AD.
Alzheimer Disease/pathology* ; Amyloid beta-Peptides/metabolism* ; Amyloid beta-Protein Precursor/metabolism* ; Animals ; Disease Models, Animal ; Humans ; Mice ; Mice, Transgenic

OBJECTIVE: To compare the clinical efficacy of abdominal acupoint thread embedding therapy based on "brain-intestinal connection" combined with donepezil hydrochloride tablets and oral donepezil hydrochloride tablets alone for mild-to-moderate Alzheimer's disease (AD) and observe its effects on amyloid precursor protein (APP) and β-amyloid protein METHODS: Sixty patients with AD were randomly divided into an observation group (30 cases, 3 cases dropped off) and a control group (30 cases, 3 cases dropped off). The patients in the control group were treated with donepezil hydrochloride tablets (5 mg per day); based on the treatment in the control group, the patients in the observation group were treated with abdominal acupoint thread embedding therapy at Zhongwan (CV 12), Xiawan (CV 10), Huaroumen (ST 24), Wailing (ST 26), Daheng (SP 15), etc., once every 10 days. Both groups were treated for 2 months. The mini-mental state examination (MMSE), Alzheimer's disease assessment scale-cognitive subscale (ADAS-Cog), activity of daily living scale (ADL), neuropsychiatric inventory questionnaire (NPI) as well as the serum levels of APP and Aβ RESULTS: After treatment, the MMSE scores in the two groups were higher than those before treatment ( CONCLUSION The abdominal acupoint thread embedding therapy based on the theory of "brain-intestinal connection" combined with donepezil hydrochloride tablets can improve cognitive function, self-care ability of daily life and mental behavior, and reduce the serum levels of APP and Aβ
Acupuncture Points ; Alzheimer Disease/drug therapy* ; Amyloid beta-Peptides ; Amyloid beta-Protein Precursor ; Brain ; Donepezil ; Humans ; Peptide Fragments

Amyloid beta (Aβ) plaques are one of the hallmarks of Alzheimer's disease (AD). However, currently available anti-amyloid therapies fail to show effectiveness in the treatment of AD in humans. It has been found that there are different types of Aβ plaque (diffuse and focal types) in the postmortem human brain. In this study, we aimed to investigate the correlations among different types of Aβ plaque and AD-related neuropathological and cognitive changes based on a postmortem human brain bank in China. The results indicated that focal plaques, but not diffuse plaques, significantly increased with age in the human hippocampus. We also found that the number of focal plaques was positively correlated with the severity of AD-related neuropathological changes (measured by the "ABC" scoring system) and cognitive decline (measured by the Everyday Cognitive Insider Questionnaire). Furthermore, most of the focal plaques were co-localized with neuritic plaques (identified by Bielschowsky silver staining) and accompanied by microglial and other inflammatory cells. Our findings suggest the potential of using focal-type but not general Aβ plaques as biomarkers for the neuropathological evaluation of AD.
Alzheimer Disease/pathology* ; Amyloid beta-Peptides/metabolism* ; Amyloid beta-Protein Precursor ; Brain/pathology* ; Cognitive Dysfunction/pathology* ; Hippocampus/metabolism* ; Humans ; Neuroinflammatory Diseases ; Plaque, Amyloid/pathology*

Silent information regulator 1 (SIRT1) is one of the seven mammalian proteins of the sirtuin family of NAD⁺-dependent deacetylases. SIRT1 plays a pivotal role in neuroprotection and ongoing research has uncovered a mechanism by which SIRT1 may exert a neuroprotective effect on Alzheimer's disease (AD). Growing evidence demonstrates that SIRT1 regulates many pathological processes including amyloid-β precursor protein (APP) processing, neuroinflammation, neurodegeneration, and mitochondrial dysfunction. SIRT1 has recently received enormous attention, and pharmacological or transgenic approaches to activate the sirtuin pathway have shown promising results in the experimental models of AD. In the present review, we delineate the role of SIRT1 in AD from a disease-centered perspective and provides an up-to-date overview of the SIRT1 modulators and their potential as effective therapeutics in AD.
Animals ; Alzheimer Disease ; Amyloid beta-Protein Precursor ; Animals, Genetically Modified ; Sirtuin 1 ; Sirtuins ; Humans

Amyloid beta-Protein Precursor ; Angiotensin II ; Anti-Inflammatory Agents/pharmacology* ; Antioxidants/pharmacology* ; HaCaT Cells ; Humans