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1.
Mol Psychiatry ; 27(8): 3533-3543, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35418601

RESUMO

Liver-generated plasma apolipoprotein E (apoE) does not enter the brain but nonetheless correlates with Alzheimer's disease (AD) risk and AD biomarker levels. Carriers of APOEε4, the strongest genetic AD risk factor, exhibit lower plasma apoE and altered brain integrity already at mid-life versus non-APOEε4 carriers. Whether altered plasma liver-derived apoE or specifically an APOEε4 liver phenotype promotes neurodegeneration is unknown. Here we investigated the brains of Fah-/-, Rag2-/-, Il2rg-/- mice on the Non-Obese Diabetic (NOD) background (FRGN) with humanized-livers of an AD risk-associated APOE ε4/ε4 versus an APOE ε2/ε3 genotype. Reduced endogenous mouse apoE levels in the brains of APOE ε4/ε4 liver mice were accompanied by various changes in markers of synaptic integrity, neuroinflammation and insulin signaling. Plasma apoE4 levels were associated with unfavorable changes in several of the assessed markers. These results propose a previously unexplored role of the liver in the APOEε4-associated risk of neurodegenerative disease.


Assuntos
Doença de Alzheimer , Doenças Neurodegenerativas , Animais , Camundongos , Apolipoproteína E4/genética , Camundongos Endogâmicos NOD , Apolipoproteínas E/genética , Encéfalo/metabolismo , Doença de Alzheimer/genética , Genótipo , Biomarcadores , Fígado/metabolismo
2.
J Alzheimers Dis ; 81(1): 339-354, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33814450

RESUMO

BACKGROUND: Altered cerebral glucose metabolism, especially prominent in APOE ɛ4 carriers, occurs years prior to symptoms in Alzheimer's disease (AD). We recently found an association between a higher ratio of plasma apolipoprotein E4 (apoE4) over apoE3, and cerebral glucose hypometabolism in cognitively healthy APOE ɛ3/ɛ4 subjects. Plasma apoE does not cross the blood-brain barrier, hence we speculate that apoE is linked to peripheral glucose metabolism which is known to affect glucose metabolism in the brain. OBJECTIVE: Explore potential associations between levels of plasma insulin and glucose with previously acquired plasma apoE, cerebral metabolic rate of glucose (CMRgl), gray matter volume, and neuropsychological test scores. METHODS: Plasma insulin and glucose levels were determined by ELISA and a glucose oxidase assay whereas apoE levels were earlier quantified by mass-spectrometry in 128 cognitively healthy APOE ɛ3/ɛ4 subjects. Twenty-five study subjects had previously undergone FDG-PET and structural MRI. RESULTS: Lower plasma apoE3 associated with higher plasma glucose but not insulin in male subjects and subjects with a body mass index above 25. Negative correlations were found between plasma glucose and CMRgl in the left prefrontal and bilateral occipital regions. These associations may have functional implications since glucose levels in turn were negatively associated with neuropsychological test scores. CONCLUSION: Plasma apoE3 but not apoE4 may be involved in insulin-independent processes governing plasma glucose levels. Higher plasma glucose, which negatively affects brain glucose metabolism, was associated with lower plasma apoE levels in APOE ɛ3/ɛ4 subjects. High plasma glucose and low apoE levels may be a hazardous combination leading to an increased risk of AD.


Assuntos
Apolipoproteína E3/sangue , Apolipoproteína E4/genética , Glicemia/análise , Idoso , Doença de Alzheimer/sangue , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Apolipoproteína E3/genética , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Feminino , Substância Cinzenta/diagnóstico por imagem , Substância Cinzenta/metabolismo , Heterozigoto , Humanos , Insulina/sangue , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos
3.
J Alzheimers Dis ; 71(4): 1217-1231, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31524156

RESUMO

The APOEɛ4 gene variant is the strongest genetic risk factor for Alzheimer's disease (AD), whereas APOEɛ3 conventionally is considered as 'risk neutral' although APOEɛ3-carriers also develop AD. Previous studies have shown that the apolipoprotein E3 (apoE3) isoform occurs as monomers, homodimers and heterodimers with apolipoprotein A-II in human body fluids and brain tissue, but the relevance of a plasma apoE3 monomer/dimer profile to AD is unknown. Here we assessed the distribution of monomers, homodimers and heterodimers in plasma from control subjects and patients with mild cognitive impairment (MCI) and AD with either a homozygous APOEɛ3 (n = 31 control subjects, and n = 14 MCI versus n = 5 AD patients) or APOEɛ4 genotype (n = 1 control subject, n = 21 MCI and n = 7 AD patients). Total plasma apoE levels were lower in APOEɛ4-carriers and overall correlated significantly to CSF Aß42, p(Thr181)-tau and t-tau levels. Apolipoprotein E dimers were only observed in the APOEɛ3-carriers and associated with total plasma apoE levels, negatively correlated to apoE monomers, but were unrelated to plasma homocysteine levels. Importantly, the APOEɛ3-carrying AD patients versus controls exhibited a significant decrease in apoE homodimers (17.8±9.6% versus 26.7±6.3%, p = 0.025) paralleled by an increase in apoE monomers (67.8±18.3% versus 48.5±11.2%, p = 0.008). In the controls, apoE monomers and heterodimers were significantly associated with plasma triglycerides; the apoE heterodimers were also associated with levels of high-density lipoprotein cholesterol. The physiological relevance of apoE dimer formation needs to be further investigated, though the distribution of apoE in monomers and dimers appears to be of relevance to AD in APOEɛ3 subjects.


Assuntos
Apolipoproteína E3 , Homocisteína/sangue , Proteínas tau/líquido cefalorraquidiano , Idoso , Doença de Alzheimer/sangue , Apolipoproteína A-II/metabolismo , Apolipoproteína E3/sangue , Apolipoproteína E3/genética , Apolipoproteína E4/sangue , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Disfunção Cognitiva/sangue , Feminino , Homozigoto , Humanos , Masculino , Estrutura Quaternária de Proteína
4.
PLoS One ; 12(3): e0173888, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28323844

RESUMO

Fe65 is an adaptor protein involved in both processing and signaling of the Alzheimer-associated amyloid-ß precursor protein, APP. Here, the subcellular localization was further investigated using TAP-tagged Fe65 constructs expressed in human neuroblastoma cells. Our results indicate that PTB2 rather than the WW domain is important for the nuclear localization of Fe65. Electrophoretic mobility shift of Fe65 caused by phosphorylation was not detected in the nuclear fraction, suggesting that phosphorylation could restrict nuclear localization of Fe65. Furthermore, both ADAM10 and γ-secretase inhibitors decreased nuclear Fe65 in a similar way indicating an important role also of α-secretase in regulating nuclear translocation.


Assuntos
Precursor de Proteína beta-Amiloide/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Nucleares/metabolismo , Proteína ADAM10/antagonistas & inibidores , Proteína ADAM10/metabolismo , Transporte Ativo do Núcleo Celular , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/química , Precursor de Proteína beta-Amiloide/genética , Linhagem Celular , Ensaio de Desvio de Mobilidade Eletroforética , Humanos , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/metabolismo , Mutagênese , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/genética , Neurônios/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/genética , Fosforilação , Domínios e Motivos de Interação entre Proteínas , Processamento de Proteína Pós-Traducional , Proteólise , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Deleção de Sequência
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