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1.
Med Mol Morphol ; 54(1): 31-40, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32572622

RESUMO

In the present study, we examined morphology and function of hippocampus in the APC1638T/1638T mouse. Expression levels of the APC mRNA and protein were both identical in the hippocampus of the APC+/+ and APC1638T/1638T mice. The dentate gyrus of the APC1638T/1638T hippocampus was thicker, and has more densely-populated granule cells in the APC1638T/1638T mouse hippocampus. Immunoelectron microscopy revealed co-localization of APC with alpha-amino-3- hydroxy-5-methyl- isoxazole-4-propionate receptor (AMPA-R) and with PSD-95 at post-synapse in the APC+/+ hippocampus, while APC1638T was co-localized with neither AMPA-R nor PSD-95 in the APC1638T/1638T hippocampus. By immunoprecipitation assay, full-length APC expressed in the APC +/+ mouse was co-immunoprecipitated with AMPA-R and PSD-95. In contrast, APC1638T expressed in the APC1638T/1638T mouse was not co-immunoprecipitated with AMPA-R and PSD-95. In the hippocampal CA1 region of the APC1638T/1638T mouse, c-Fos expression after electric foot shock was decreased compared with the APC+/+ mouse. The present study showed some abnormalities on morphology of the hippocampus caused by a truncated APC (APC1638T). Also, our findings suggest that failure in APC binding to AMPA-R and PSD-95 may bring about less activities of hippocampal neurons in the APC1638T/1638T mouse.


Assuntos
Proteína da Polipose Adenomatosa do Colo/metabolismo , Hipocampo/patologia , Proteína da Polipose Adenomatosa do Colo/análise , Proteína da Polipose Adenomatosa do Colo/genética , Animais , Proteína 4 Homóloga a Disks-Large/análise , Proteína 4 Homóloga a Disks-Large/metabolismo , Camundongos , Camundongos Transgênicos , Microscopia Imunoeletrônica , Mutação , Receptores de AMPA/análise , Receptores de AMPA/metabolismo
2.
Med Mol Morphol ; 52(1): 1-7, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29687167

RESUMO

There are several theories regarding the etiologies of Alzheimer disease (AD). Considering that all genes responsible for familial AD are amyloid protein precursor (APP) or APP metabolizing enzymes, surely aberrant APP metabolism is crucial to pathogenesis of AD. BRI2, a type II transmembrane protein, binds APP and inhibits all α, ß, and γ pathways of APP proteolysis. Crossing AD model mice with BRI2 transgenic or BRI2 knockout mice confirmed that BRI2 is an anti-Alzheimer gene. Mutations of BRI2 are known to cause rare familial dementias in human. Analysis of knock-in mice harboring the disease mutation revealed the memory defect in the mice, attributable to loss of protective function of BRI2. Further studies are needed to decipher this anti-Alzheimer mechanism of BRI2 to develop a novel therapeutic application for AD. In this review, after describing basic assumptions in AD study, we focus on BRI2 as an anti-Alzheimer gene.


Assuntos
Doença de Alzheimer/metabolismo , Modelos Animais de Doenças , Proteínas de Membrana/genética , Proteínas Adaptadoras de Transdução de Sinal , Doença de Alzheimer/genética , Animais , Catarata , Ataxia Cerebelar , Surdez , Demência , Humanos , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Mutação
3.
Med Mol Morphol ; 51(4): 227-236, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29923125

RESUMO

Adenomatous polyposis coli (APC) is a large protein with multiple binding partners, suggesting diverse functions besides its well-known role in the destruction of ß-catenin. To elucidate these complex functions, it is crucial to evaluate the precise subcellular distribution of APC within a cell and tissue. However, most of the commercially available anti-APC antibodies can only be used for limited applications, resulting in the use of independently generated antibodies. This has led to various discrepancies between studies as a common antibody has not been established. In this study, we generated an antibody against the c-terminal domain of human APC, designated APC-C antibody, and evaluated its specificity and application in various immunological methods. Our data indicate that this novel APC-C antibody is a specific and versatile antibody that can be used in western blotting, immunoprecipitation, immunocytochemistry, and immunohistochemistry. Widespread use of this APC antibody will help enhance our understanding of APC's function in both normal and cancer cell biology.


Assuntos
Proteína da Polipose Adenomatosa do Colo/imunologia , Anticorpos , Western Blotting , Humanos , Imuno-Histoquímica , Imunoprecipitação
4.
Med Mol Morphol ; 50(2): 94-102, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28070680

RESUMO

The adenomatous polyposis coli (APC) is a multifunctional protein as well as a tumor suppressor. To determine the functions of the C-terminal domain of APC, we explored APC 1638T/1638T (APC1638T) mice that express a truncated APC lacking the C-terminal domain. The APC1638T mice were tumor free and exhibited growth retardation. In the present study, we compared small intestinal crypt-villus cells homeostasis in APC +/+ (WT) mice and APC1638T mice. The body weight of APC1638T mice was significantly smaller than that of WT mice at all ages. The length of small intestine of APC1638T mice was significantly shorter than that of WT mice. The crypt-villus axis was significantly elongated, and the number of intestinal epithelial cells also increased in APC1638T mice compared with those in WT mice. However, the number of intestinal epithelial cells per 100 µm of villi was not different between WT and APC1638T mice. Migration and proliferation of intestinal epithelial cells in APC1638T mice were faster than that in WT mice. The population of Goblet cells, Paneth cells, and enteroendocrine cells was significantly altered in APC1638T mice. These results indicate that C-terminal domain of APC has a role in the regulation of intestinal epithelium homeostasis.


Assuntos
Proteína da Polipose Adenomatosa do Colo/genética , Células Enteroendócrinas/patologia , Células Caliciformes/patologia , Mucosa Intestinal/patologia , Intestino Delgado/patologia , Celulas de Paneth/patologia , Proteína da Polipose Adenomatosa do Colo/metabolismo , Animais , Sequência de Bases , Tamanho Corporal , Contagem de Células , Movimento Celular , Proliferação de Células , Células Enteroendócrinas/metabolismo , Feminino , Expressão Gênica , Células Caliciformes/metabolismo , Mucosa Intestinal/metabolismo , Intestino Delgado/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Celulas de Paneth/metabolismo , Domínios Proteicos , Deleção de Sequência
5.
FEBS J ; 283(8): 1475-87, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26896672

RESUMO

Translocated in liposarcoma/fused in sarcoma (TLS/FUS) is an RNA-binding protein that regulates the splicing pattern of mRNA transcripts and is known to cause a type of familial amyotrophic lateral sclerosis (ALS). In the absence of TLS, Mammalian enabled (Mena), an actin-regulatory protein and a target of TLS, undergoes preferential alternative splicing. In the present study, we show that the ablation of TLS dysregulates the subcellular location and functions of Mena. When TLS knockout (KO) mouse embryonic fibroblasts (MEFs) were transfected with wild-type Mena, it no longer accumulated at focal adhesions and peripheral structures, whereas the localization of the alternatively spliced form was maintained. Additionally, the ability of Mena to suppress the motility of cells was lost in TLS KO MEFs. Moreover, Mena failed to promote neurite outgrowth in TLS KO primary neurons. Taken together, TLS is intimately involved in the local cytoskeletal dynamics surrounding Mena in both fibroblasts and neurons. The robust change in cytoskeletal dynamics, as indicated by the dysregulation of Mena in TLS KO cells, provides a new insight into the pathogenesis of certain types of ALS.


Assuntos
Citoesqueleto de Actina/fisiologia , Proteínas do Citoesqueleto/metabolismo , Embrião de Mamíferos/metabolismo , Fibroblastos/metabolismo , Neurônios/metabolismo , Proteína FUS de Ligação a RNA/fisiologia , Sequência de Aminoácidos , Animais , Western Blotting , Diferenciação Celular , Células Cultivadas , Proteínas do Citoesqueleto/genética , Embrião de Mamíferos/citologia , Feminino , Fibroblastos/citologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas dos Microfilamentos , Microscopia de Fluorescência , Dados de Sequência Molecular , Mutação , Neurônios/citologia , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
6.
J Biomed Biotechnol ; 2012: 728178, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22619496

RESUMO

A dominant mutation in the ITM2B/BRI2 gene causes familial Danish dementia (FDD) in humans. To model FDD in animal systems, a knock-in approach was recently implemented in mice expressing a wild-type and mutant allele, which bears the FDD-associated mutation. Since these FDD(KI) mice show behavioural alterations and impaired synaptic function, we characterized their synaptosomal proteome via two-dimensional differential in-gel electrophoresis. After identification by nanoliquid chromatography coupled to electrospray-linear ion trap tandem mass spectrometry, the differentially expressed proteins were classified according to their gene ontology descriptions and their predicted functional interactions. The Dlg4/Psd95 scaffold protein and additional signalling proteins, including protein phosphatases, were revealed by STRING analysis as potential players in the altered synaptic function of FDD(KI) mice. Immunoblotting analysis finally demonstrated the actual downregulation of the synaptosomal scaffold protein Dlg4/Psd95 and of the dual-specificity phosphatase Dusp3 in the synaptosomes of FDD(KI) mice.


Assuntos
Catarata/metabolismo , Ataxia Cerebelar/metabolismo , Surdez/metabolismo , Demência/metabolismo , Modelos Animais de Doenças , Proteoma/análise , Animais , Western Blotting , Eletroforese em Gel Bidimensional , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteômica , Reprodutibilidade dos Testes , Espectrometria de Massas por Ionização por Electrospray
7.
EMBO Mol Med ; 4(3): 171-9, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22170863

RESUMO

A mutation in the BRI2/ITM2b gene causes loss of BRI2 protein leading to familial Danish dementia (FDD). BRI2 deficiency of FDD provokes an increase in amyloid-ß precursor protein (APP) processing since BRI2 is an inhibitor of APP proteolysis, and APP mediates the synaptic/memory deficits in FDD. APP processing is linked to Alzheimer disease (AD) pathogenesis, which is consistent with a common mechanism involving toxic APP metabolites in both dementias. We show that inhibition of APP cleavage by ß-secretase rescues synaptic/memory deficits in a mouse model of FDD. ß-cleavage of APP yields amino-terminal-soluble APPß (sAPPß) and ß-carboxyl-terminal fragments (ß-CTF). Processing of ß-CTF by γ-secretase releases amyloid-ß (Aß), which is assumed to cause AD. However, inhibition of γ-secretase did not ameliorate synaptic/memory deficits of FDD mice. These results suggest that sAPPß and/or ß-CTF, rather than Aß, are the toxic species causing dementia, and indicate that reducing ß-cleavage of APP is an appropriate therapeutic approach to treating human dementias. Our data and the failures of anti-Aß therapies in humans advise against targeting γ-secretase cleavage of APP and/or Aß.


Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Catarata/enzimologia , Catarata/psicologia , Ataxia Cerebelar/enzimologia , Ataxia Cerebelar/psicologia , Surdez/enzimologia , Surdez/psicologia , Demência/enzimologia , Demência/psicologia , Memória , Plasticidade Neuronal , Proteínas Adaptadoras de Transdução de Sinal , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Peptídeos beta-Amiloides/genética , Animais , Catarata/genética , Catarata/fisiopatologia , Ataxia Cerebelar/genética , Ataxia Cerebelar/fisiopatologia , Surdez/genética , Surdez/fisiopatologia , Demência/genética , Demência/fisiopatologia , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Proteólise , Sinapses/fisiologia
8.
J Alzheimers Dis ; 27(2): 385-91, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21841249

RESUMO

An autosomal dominant mutation in the BRI2/ITM2B gene causes Familial Danish Dementia (FDD). We have generated a mouse model of FDD, called FDDKI, genetically congruous to the human disease. These mice carry one mutant and one wild type Bri2/Itm2b allele, like FDD patients. Analysis of FDDKI mice and samples from human patients has shown that the Danish mutation causes loss of Bri2 protein. FDDKI mice show synaptic plasticity and memory impairments. BRI2 is a physiological interactor of amyloid-ß protein precursor (AßPP), a gene associated with Alzheimer's disease, which inhibits processing of AßPP. AßPP/Bri2 complexes are reduced in synaptic membranes of FDDKI mice. Consequently, AßPP metabolites derived from processing of AßPP by ß-, α-, and γ-secretases are increased in Danish dementia mice. AßPP haplodeficiency prevents memory and synaptic dysfunctions, consistent with a role for AßPP-metabolites in the pathogenesis of memory and synaptic deficits. This genetic suppression provides compelling evidence that AßPP and BRI2 functionally interact. Here, we have investigated whether AßPP processing is altered in FDD patients' brain samples. We find that the levels of several AßPP metabolites, including Aß, are significantly increased in the brain sample derived from an FDD patient. Our data are consistent with the findings in FDDKI mice, and support the hypothesis that the neurological effects of the Danish form of BRI2 are caused by toxic AßPP metabolites, suggesting that Familial Danish and Alzheimer's dementias share common pathogenic mechanisms.


Assuntos
Precursor de Proteína beta-Amiloide/biossíntese , Catarata/metabolismo , Ataxia Cerebelar/metabolismo , Surdez/metabolismo , Demência/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Doença de Alzheimer/etiologia , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/efeitos adversos , Precursor de Proteína beta-Amiloide/genética , Química Encefálica/genética , Catarata/etiologia , Catarata/genética , Ataxia Cerebelar/etiologia , Ataxia Cerebelar/genética , Surdez/etiologia , Surdez/genética , Demência/etiologia , Demência/genética , Humanos , Proteínas de Membrana/efeitos adversos , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Processamento de Proteína Pós-Traducional/genética , Regulação para Cima/genética
9.
EMBO J ; 30(12): 2501-9, 2011 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-21587206

RESUMO

An autosomal dominant mutation in the BRI2/ITM2B gene causes familial Danish dementia (FDD). Analysis of FDD(KI) mice, a mouse model of FDD genetically congruous to the human disease since they carry one mutant and one wild-type Bri2/Itm2b allele, has shown that the Danish mutation causes loss of Bri2 protein, synaptic plasticity and memory impairments. BRI2 is a physiological interactor of Aß-precursor protein (APP), a gene associated with Alzheimer disease, which inhibits processing of APP. Here, we show that APP/Bri2 complexes are reduced in synaptic membranes of FDD(KI) mice. Consequently, APP metabolites derived from processing of APP by ß-, α- and γ-secretases are increased in Danish dementia mice. APP haplodeficiency prevents memory and synaptic dysfunctions, consistent with a role for APP metabolites in the pathogenesis of memory and synaptic deficits. This genetic suppression provides compelling evidence that APP and BRI2 functionally interact, and that the neurological effects of the Danish form of BRI2 only occur when sufficient levels of APP are supplied by two alleles. This evidence establishes a pathogenic sameness between familial Danish and Alzheimer's dementias.


Assuntos
Peptídeos beta-Amiloides/genética , Demência/genética , Triagem de Portadores Genéticos , Proteínas de Membrana/genética , Transtornos da Memória/genética , Fragmentos de Peptídeos/genética , Proteínas Adaptadoras de Transdução de Sinal , Doença de Alzheimer/genética , Animais , Dinamarca , Modelos Animais de Doenças , Técnicas de Introdução de Genes , Humanos , Masculino , Proteínas de Membrana/metabolismo , Transtornos da Memória/prevenção & controle , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Mutantes Quiméricas/genética , Mutação
10.
Neurobiol Aging ; 32(8): 1400-8, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19748705

RESUMO

Processing of the amyloid-ß (Aß) precursor protein (APP) has been extensively studied since it leads to production of Aß peptides. Toxic forms of Aß aggregates are considered the cause of Alzheimer's disease (AD). On the other end, BRI2 is implicated in APP processing and Aß production. We have investigated the precise mechanism by which BRI2 modulates APP cleavages and have found that BRI2 forms a mature BRI2 polypeptide that is transported to the plasma membrane and endosomes where it interacts with mature APP. Notably, immature forms of APP and BRI2 fail to interact. Mature BRI2 inhibits APP processing by α-, ß- and γ-secretases on the plasma membrane and in endocytic compartments. Thus, BRI2 is a specific inhibitor that reduces secretases' access to APP in the intracellular compartments where APP is normally processed.


Assuntos
Doença de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/fisiologia , Membrana Celular/metabolismo , Glicoproteínas de Membrana/biossíntese , Processamento de Proteína Pós-Traducional , Vesículas Transportadoras/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Doença de Alzheimer/enzimologia , Doença de Alzheimer/genética , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Membrana Celular/enzimologia , Membrana Celular/genética , Fibroblastos/citologia , Fibroblastos/metabolismo , Células HEK293 , Células HeLa , Humanos , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/fisiologia , Camundongos , Vesículas Transportadoras/enzimologia , Vesículas Transportadoras/genética
11.
Proc Natl Acad Sci U S A ; 107(48): 20822-7, 2010 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-21098268

RESUMO

According to the prevailing "amyloid cascade hypothesis," genetic dementias such as Alzheimer's disease and familial Danish dementia (FDD) are caused by amyloid deposits that trigger tauopathy, neurodegeneration, and behavioral/cognitive alterations. To efficiently reproduce amyloid lesions, murine models of human dementias invariably use transgenic expression systems. However, recent FDD transgenic models showed that Danish amyloidosis does not cause memory defects, suggesting that other mechanisms cause Danish dementia. We studied an animal knock-in model of FDD (FDD(KI/+)) genetically congruous with human cases. FDD(KI/+) mice present reduced Bri2 levels, impaired synaptic plasticity and severe hippocampal memory deficits. These animals show no cerebral lesions that are reputed characteristics of human dementia, such as tangles or amyloid plaques. Bri2(+/-) mice exhibit synaptic and memory deficits similar to FDD(KI/+) mice, and memory loss of FDD(KI/+) mice is prevented by expression of WT BRI2, indicating that Danish dementia is caused by loss of BRI2 function. Together, the data suggest that clinical dementia in Danish patients occurs via a loss of function mechanism and not as a result of amyloidosis and tauopathy.


Assuntos
Amiloide/metabolismo , Transtornos da Memória/complicações , Transtornos da Memória/fisiopatologia , Plasticidade Neuronal/fisiologia , Transdução de Sinais , Sinapses/patologia , Proteínas Adaptadoras de Transdução de Sinal , Amiloidose/complicações , Amiloidose/patologia , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/fisiopatologia , Catarata/complicações , Catarata/patologia , Catarata/fisiopatologia , Ataxia Cerebelar/complicações , Ataxia Cerebelar/patologia , Ataxia Cerebelar/fisiopatologia , Surdez/complicações , Surdez/patologia , Surdez/fisiopatologia , Demência/complicações , Demência/patologia , Demência/fisiopatologia , Células HeLa , Humanos , Potenciação de Longa Duração/fisiologia , Glicoproteínas de Membrana , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Mutação/genética , Sinapses/metabolismo
12.
PLoS One ; 4(11): e7900, 2009 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-19924302

RESUMO

BACKGROUND: Mutations in the integral membrane protein 2B, also known as BRI(2), a type II trans-membrane domain protein cause two autosomal dominant neurodegenerative diseases, Familial British and Danish Dementia. In these conditions, accumulation of a C-terminal peptide (ABri and ADan) cleaved off from the mutated precursor protein by the pro-protein convertase furin, leads to amyloid deposition in the walls of blood vessels and parenchyma of the brain. Recent advances in the understanding of the generation of amyloid in Alzheimer's disease has lead to the finding that BRI(2) interacts with the Amyloid Precursor Protein (APP), decreasing the efficiency of APP processing to generate Abeta. The interaction between the two precursors, APP and BRI(2), and possibly between Abeta and ABri or ADan, could be important in influencing the rate of amyloid production or the tendency of these peptides to aggregate. METHODOLOGY/PRINCIPAL FINDINGS: We have generated the first BRI(2) Danish Knock-In (FDD(KI)) murine model of FDD, expressing the pathogenic decamer duplication in exon 6 of the BRI(2) gene. FDD(KI) mice do not show any evident abnormal phenotype, with normal brain histology and no detectable amyloid deposition in blood vessel walls or parenchyma. CONCLUSIONS/SIGNIFICANCE: This new murine mouse model will be important to further understand the interaction between APP and BRI(2), and to provide insights into the molecular basis of FDD.


Assuntos
Demência/metabolismo , Camundongos Transgênicos , Mutação , Doenças Neurodegenerativas/metabolismo , Precursor de Proteína beta-Amiloide , Animais , Encéfalo/patologia , Primers do DNA/química , Demência/genética , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Peptídeos/química , Fenótipo , Estrutura Terciária de Proteína
13.
Mol Neurodegener ; 4: 41, 2009 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-19849849

RESUMO

BACKGROUND: Alzheimer disease (AD) is characterized by senile plaques, which are mainly composed of beta amyloid (Abeta) peptides. Abeta is cleaved off from amyloid precursor protein (APP) with consecutive proteolytic processing by beta-secretase and gamma-secretase. RESULTS: Here, we show that CD74, the invariant chain of class II major histocompatibility complex, interacts with APP and serves as a negative regulator of Abeta. CD74 resembles other APP interacters such as BRI2 and BRI3, since all of them reduce the level of Abeta. However, unlike BRIs, CD74 does not reduce the secretion of sAPPalpha or sAPPbeta. Interestingly, in HeLa cells, over expression of CD74 steers APP, but not Notch, to large vacuoles created by CD74. CONCLUSION: Taken together, we propose that CD74 inhibits Abeta production by interacting with and derailing normal trafficking of APP.

14.
J Biol Chem ; 284(23): 15815-25, 2009 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-19366692

RESUMO

Alzheimer disease (AD) is characterized by senile plaques, which are mainly composed of beta amyloid (Abeta) peptides. Abeta is cleaved off from amyloid precursor protein (APP) with consecutive proteolytic processing: beta-secretase, followed by gamma-secretase. Here, we show that BRI3, a member of the BRI gene family that includes the familial British and Danish dementia gene BRI2, interacts with APP and serves as an endogenous negative regulator of Abeta production. BRI3 colocalizes with APP along neuritis in differentiated N2a cells; endogenous BRI3-APP complexes are readily detectable in mouse brain extract; reducing endogenous BRI3 levels by RNA interference results in increased Abeta secretion. BRI3 resembles BRI2, because BRI3 overexpression reduces both alpha- and beta-APP cleavage. We propose that BRI3 inhibits the various processing of APP by blocking the access of alpha- and beta-secretases to APP. However, unlike BRI2, the binding of BRI3 to the beta-secretase cleaved APP C-terminal fragment is negligible and BRI3 does not cause the massive accumulation of this APP fragment, suggesting that, unlike BRI2, BRI3 is a poor gamma-cleavage inhibitor. Competitive inhibition of APP processing by BRI3 may provide a new approach to AD therapy and prevention.


Assuntos
Amiloide/antagonistas & inibidores , Demência/genética , Proteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Doença de Alzheimer/genética , Doença de Alzheimer/prevenção & controle , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Linhagem Celular , Clonagem Molecular , Códon de Terminação , Primers do DNA , Células HeLa , Humanos , Rim , Glicoproteínas de Membrana , Proteínas de Membrana/genética , Camundongos , Pessoa de Meia-Idade , Mutação , Proteínas do Tecido Nervoso/genética , Ligação Proteica , Transfecção
15.
J Neurosci ; 28(35): 8668-76, 2008 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-18753367

RESUMO

Genetic alterations of amyloid beta-peptide (Abeta) production caused by mutations in the Abeta precursor protein (APP) cause familial Alzheimer's disease (AD). Mutations in BRI2, a gene of undefined function, are linked to familial British and Danish dementias, which are pathologically and clinically similar to Alzheimer's disease. We report that BRI2 is a physiological suppressor of Abeta production. BRI2 restrict docking of gamma-secretase to APP and access of alpha- and beta-secretases to their cleavage APP sequences. Alterations of BRI2 by gene targeting or transgenic expression regulate Abeta levels and AD pathology in mouse models of AD. Competitive inhibition of APP processing by BRI2 may provide a new approach to AD therapy and prevention.


Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Proteínas de Membrana/fisiologia , Proteínas Adaptadoras de Transdução de Sinal , Peptídeos beta-Amiloides/metabolismo , Animais , Encéfalo/metabolismo , Linhagem Celular , Inibidores Enzimáticos/farmacologia , Ensaio de Imunoadsorção Enzimática/métodos , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Humanos , Glicoproteínas de Membrana , Proteínas de Membrana/genética , Camundongos , Camundongos Transgênicos , Mutação/fisiologia , Ligação Proteica/efeitos dos fármacos , Transfecção/métodos
17.
J Biol Chem ; 280(32): 28912-6, 2005 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-15983050

RESUMO

Alzheimer disease (AD), the most common senile dementia, is characterized by amyloid plaques, vascular amyloid, neurofibrillary tangles, and progressive neurodegeneration. Amyloid is mainly composed by amyloid-beta (A(beta)) peptides, which are derive from processing of the beta-amyloid precursor protein (APP), better named amyloid-beta precursor protein (A(beta)PP), by secretases. The A(beta)PP intracellular domain (AID), which is released together with A(beta), has signaling function, since it modulates apoptosis and transcription. Despite its biological and pathological importance, the mechanisms regulating A(beta)PP processing are poorly understood. As cleavage of other gamma-secretase substrates is regulated by membrane bound proteins, we have postulated the existence of integral membrane proteins that bind A(beta)PP and regulate its processing. Here, we show that BRI2, a type II membrane protein, interacts with A(beta)PP. Interestingly, 17 amino acids corresponding to the NH2-terminal portion of A(beta) are necessary for this interaction. Moreover, BRI2 expression regulates A(beta)PP processing resulting in reduced A(beta) and AID levels. Altogether, these findings characterize the BRI2-A(beta)PP interaction as a regulatory mechanism of A(beta)PP processing that inhibits A(beta) production. Notably, BRI2 mutations cause familial British (FBD) and Danish dementias (FDD) that are clinically and pathologically similar to AD. Finding that BRI2 pathogenic mutations alter the regulatory function of BRI2 on A(beta)PP processing would define dysregulation of A(beta)PP cleavage as a pathogenic mechanism common to AD, FDD, and FBD.


Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/genética , Precursor de Proteína beta-Amiloide/genética , Amiloide/metabolismo , Amiloide/fisiologia , Proteínas Adaptadoras de Transdução de Sinal , Apoptose , Encéfalo/metabolismo , Linhagem Celular , Membrana Celular/metabolismo , Citoplasma/metabolismo , Demência/metabolismo , Ensaio de Imunoadsorção Enzimática , Células HeLa , Humanos , Ligantes , Luciferases/metabolismo , Glicoproteínas de Membrana , Proteínas de Membrana , Mutação , Peptídeos/química , Plasmídeos/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Transdução de Sinais , Transcrição Gênica , Transfecção , Técnicas do Sistema de Duplo-Híbrido
18.
Mol Neurobiol ; 30(2): 185-200, 2004 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-15475626

RESUMO

Alzheimer's disease is characterized pathologically by senile plaques in the brain. The major component of senile plaques is amyloid-beta (Abeta), which is cleaved from Alzheimer's Abeta protein precursor (AbetaPP). Recently, information regarding the cytoplasmic tail of AbetaPP has started to emerge, opening up various insights into the physiological roles of AbetaPP and its pathological role in Alzheimer's disease. The cytoplasmic domain of AbetaPP shares the evolutionarily conserved GYENPTY motif, which binds to a number of adaptor proteins containing the phosphotyrosine interaction domain (PID). Among the PID-containing proteins, this article focuses on four groups of adaptor proteins of AbetaPP: Fe65, X11, mDab1, and c-Jun N-terminal kinase-interacting protein 1b/islet-brain 1.


Assuntos
Doença de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Citoplasma/metabolismo , Doença de Alzheimer/genética , Sequência de Aminoácidos , Precursor de Proteína beta-Amiloide/genética , Animais , Citoplasma/genética , Humanos , Dados de Sequência Molecular
19.
Nat Cell Biol ; 6(2): 146-53, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14743220

RESUMO

NF-kappa B/Rel transcription factors control apoptosis, also known as programmed cell death. This control is crucial for oncogenesis, cancer chemo-resistance and for antagonizing tumour necrosis factor alpha (TNFalpha)-induced killing. With regard to TNFalpha, the anti-apoptotic activity of NF-kappa B involves suppression of the c-Jun N-terminal kinase (JNK) cascade. Using an unbiased screen, we have previously identified Gadd45 beta/Myd118, a member of the Gadd45 family of inducible factors, as a pivotal mediator of this suppressive activity of NF-kappa B. However, the mechanisms by which Gadd45 beta inhibits JNK signalling are not understood. Here, we identify MKK7/JNKK2--a specific and essential activator of JNK--as a target of Gadd45 beta, and in fact, of NF-kappa B itself. Gadd45 beta binds to MKK7 directly and blocks its catalytic activity, thereby providing a molecular link between the NF-kappa B and JNK pathways. Importantly, Gadd45 beta is required to antagonize TNFalpha-induced cytotoxicity, and peptides disrupting the Gadd45 beta/MKK7 interaction hinder the ability of Gadd45 beta, as well as of NF-kappa B, to suppress this cytotoxicity. These findings establish a basis for the NF-kappa B control of JNK activation and identify MKK7 as a potential target for anti-inflammatory and anti-cancer therapy.


Assuntos
Antígenos de Diferenciação/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Transdução de Sinais/fisiologia , Sequência de Aminoácidos , Animais , Apoptose/fisiologia , Células Cultivadas , Ativação Enzimática , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno , MAP Quinase Quinase 7 , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Peptídeos/genética , Peptídeos/metabolismo , Ligação Proteica , Alinhamento de Sequência , Fator de Necrose Tumoral alfa/metabolismo
20.
J Biol Chem ; 278(40): 38601-6, 2003 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-12893827

RESUMO

Proteolytic processing of amyloid beta protein precursor (AbetaPP) generates peptides that regulate normal cell signaling and are implicated in Alzheimer's disease pathogenesis. AbetaPP processing also occurs in nerve processes where AbetaPP is transported from the cell body by kinesin-I, a microtubule motor composed of two kinesin heavy chain and two kinesin light chain (Klc) subunits. AbetaPP transport is supposedly mediated by the direct AbetaPP-Klc1 interaction. Here we demonstrate that the AbetaPP-Klc1 interaction is not direct but is mediated by JNK-interacting protein 1 (JIP1). The phosphotyrosine binding domain of JIP1 binds the cytoplasmic tail of AbetaPP, whereas the JIP1 C-terminal region interacts with the tetratrico-peptide repeats of Klc1. We also show that JIP1 does not bridge the AbetaPP gene family member AbetaPP-like protein 2, APLP2, to Klc1. These results support a model where JIP1 mediates the interaction of AbetaPP to the motor protein kinesin-I and that this JIP1 function is unique for AbetaPP relative to its family member APLP2. Our data suggest that kinesin-I-dependent neuronal AbetaPP transport, which controls AbetaPP processing, may be regulated by JIP1.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/química , Proteínas de Transporte/química , Proteínas Associadas aos Microtúbulos/química , Proteínas do Tecido Nervoso/química , Sequência de Aminoácidos , Proteínas de Transporte/metabolismo , Linhagem Celular , Membrana Celular/metabolismo , Citoplasma/metabolismo , Vetores Genéticos , Glutationa Transferase/metabolismo , Proteínas de Fluorescência Verde , Humanos , Cinesinas , Proteínas Luminescentes/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Modelos Biológicos , Dados de Sequência Molecular , Peptídeos/química , Fosfotirosina/química , Plasmídeos/metabolismo , Testes de Precipitina , Ligação Proteica , Precursores de Proteínas , Estrutura Terciária de Proteína , Transporte Proteico , Proteínas Recombinantes de Fusão/química , Transdução de Sinais , Transfecção , Técnicas do Sistema de Duplo-Híbrido
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