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1.
Mol Cell Neurosci ; 57: 54-62, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24128662

RESUMO

Neuronal damage in HIV-associated Neurocognitive Disorders (HAND) has been linked to inflammation induced by soluble factors released by HIV-infected, and non-infected, activated macrophages/microglia (HIV M/M) in the brain. It has been suggested that aberrant neuronal cell cycle activation determines cell fate in response to these toxic factors. We have previously shown increased expression of cell cycle proteins such as E2F1 and phosphorylated pRb in HAND midfrontal cortex in vivo and in primary neurons exposed to HIV M/M supernatants in vitro. In addition, we have previously shown that MDMx (also referred to as MDM4), a negative regulator of E2F1, was decreased in the brain in a primate model of HIV-induced CNS neurodegeneration. Thus, we hypothesized that MDMx provides indirect neuroprotection from HIV-induced neurodegeneration in our in vitro model. In this report, we found significant reductions in MDMx protein levels in the mid-frontal cortex of patients with HAND. In addition, treatment of primary rat neuroglial cultures with HIV M/M led to NMDA receptor- and calpain-dependent degradation of MDMx and decreased neuronal survival, while overexpression of MDMx conferred partial protection from HIV M/M toxicity in vitro. Further, our results demonstrate that MDMx is a novel and direct calpain substrate. Finally, blocking MDMx activity led to neuronal death in vitro in the absence of toxic stimulus, which was reversed by calpain inhibition. Overall, our results indicate that MDMx plays a pro-survival role in neurons, and that strategies to stabilize and/or induce MDMx can provide neuroprotection in HAND and in other neurodegenerative diseases where calpain activation contributes to neuropathogenesis.


Assuntos
Complexo AIDS Demência/metabolismo , Calpaína/metabolismo , Lobo Frontal/metabolismo , Neuroglia/metabolismo , Neurônios/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Complexo AIDS Demência/imunologia , Complexo AIDS Demência/patologia , Animais , Proteínas de Ciclo Celular , Morte Celular , Células Cultivadas , Meios de Cultivo Condicionados/toxicidade , Lobo Frontal/patologia , HIV-1/imunologia , HIV-1/patogenicidade , Humanos , Ativação de Macrófagos , Macrófagos/imunologia , Macrófagos/virologia , Neuroglia/efeitos dos fármacos , Neuroglia/patologia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Proteínas Nucleares/genética , Proteólise , Proteínas Proto-Oncogênicas/genética , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/metabolismo
2.
J Mol Biol ; 432(8): 2633-2650, 2020 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-32105735

RESUMO

Lysosomal dysfunction is considered pathogenic in Alzheimer disease (AD). Loss of presenilin-1 (PSEN1) function causing AD impedes acidification via defective vacuolar ATPase (vATPase) V0a1 subunit delivery to lysosomes. We report that isoproterenol (ISO) and related ß2-adrenergic agonists reacidify lysosomes in PSEN1 Knock out (KO) cells and fibroblasts from PSEN1 familial AD patients, which restores lysosomal proteolysis, calcium homeostasis, and normal autophagy flux. We identify a novel rescue mechanism involving Portein Kinase A (PKA)-mediated facilitation of chloride channel-7 (ClC-7) delivery to lysosomes which reverses markedly lowered chloride (Cl-) content in PSEN1 KO lysosomes. Notably, PSEN1 loss of function impedes Endoplasmic Reticulum (ER)-to-lysosome delivery of ClC-7. Transcriptomics of PSEN1-deficient cells reveals strongly downregulated ER-to-lysosome transport pathways and reversibility by ISO, thus accounting for lysosomal Cl- deficits that compound pH elevation due to deficient vATPase and its rescue by ß2-adrenergic agonists. Our findings uncover a broadened PSEN1 role in lysosomal ion homeostasis and novel pH modulation of lysosomes through ß2-adrenergic regulation of ClC-7, which can potentially be modulated therapeutically.


Assuntos
Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Canais de Cloreto/metabolismo , Retículo Endoplasmático/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Lisossomos/efeitos dos fármacos , Mutação , Presenilina-1/fisiologia , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Animais , Cálcio/metabolismo , Cloretos/metabolismo , Retículo Endoplasmático/metabolismo , Fibroblastos/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Lisossomos/metabolismo , Camundongos , Camundongos Knockout , Presenilina-1/genética , Receptores Adrenérgicos beta 2/química
3.
Free Radic Biol Med ; 114: 40-51, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28988799

RESUMO

Individuals with Down syndrome (DS) have an increased risk of early-onset Alzheimer's Disease (AD), largely owing to a triplication of the APP gene, located on chromosome 21. In DS and AD, defects in endocytosis and lysosomal function appear at the earliest stages of disease development and progress to widespread failure of intraneuronal waste clearance, neuritic dystrophy and neuronal cell death. The same genetic factors that cause or increase AD risk are also direct causes of endosomal-lysosomal dysfunction, underscoring the essential partnership between this dysfunction and APP metabolites in AD pathogenesis. The appearance of APP-dependent endosome anomalies in DS beginning in infancy and evolving into the full range of AD-related endosomal-lysosomal deficits provides a unique opportunity to characterize the earliest pathobiology of AD preceding the classical neuropathological hallmarks. Facilitating this characterization is the authentic recapitulation of this endosomal pathobiology in peripheral cells from people with DS and in trisomy mouse models. Here, we review current research on endocytic-lysosomal dysfunction in DS and AD, the emerging importance of APP/ßCTF in initiating this dysfunction, and the potential roles of additional trisomy 21 genes in accelerating endosomal-lysosomal impairment in DS. Collectively, these studies underscore the growing value of investigating DS to probe the biological origins of AD as well as to understand and ameliorate the developmental disability of DS.


Assuntos
Doença de Alzheimer/patologia , Autofagia , Síndrome de Down/patologia , Endossomos/metabolismo , Lisossomos/metabolismo , Doença de Alzheimer/metabolismo , Animais , Síndrome de Down/metabolismo , Endossomos/patologia , Humanos , Lisossomos/patologia
4.
Ageing Res Rev ; 32: 75-88, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27197071

RESUMO

Autophagy and endocytosis deliver unneeded cellular materials to lysosomes for degradation. Beyond processing cellular waste, lysosomes release metabolites and ions that serve signaling and nutrient sensing roles, linking the functions of the lysosome to various pathways for intracellular metabolism and nutrient homeostasis. Each of these lysosomal behaviors is influenced by the intraluminal pH of the lysosome, which is maintained in the low acidic range by a proton pump, the vacuolar ATPase (v-ATPase). New reports implicate altered v-ATPase activity and lysosomal pH dysregulation in cellular aging, longevity, and adult-onset neurodegenerative diseases, including forms of Parkinson disease and Alzheimer disease. Genetic defects of subunits composing the v-ATPase or v-ATPase-related proteins occur in an increasingly recognized group of familial neurodegenerative diseases. Here, we review the expanding roles of the v-ATPase complex as a platform regulating lysosomal hydrolysis and cellular homeostasis. We discuss the unique vulnerability of neurons to persistent low level lysosomal dysfunction and review recent clinical and experimental studies that link dysfunction of the v-ATPase complex to neurodegenerative diseases across the age spectrum.


Assuntos
Envelhecimento/fisiologia , Lisossomos , Doenças Neurodegenerativas/metabolismo , ATPases Vacuolares Próton-Translocadoras/metabolismo , Autofagia/fisiologia , Restrição Calórica , Humanos , Lisossomos/enzimologia , Lisossomos/metabolismo , Transdução de Sinais/fisiologia
5.
Neurosci Lett ; 609: 182-8, 2015 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-26477779

RESUMO

MDMx/MDM4 is a negative regulator of the p53 tumor suppressor protein and is necessary for survival in dividing cells. MDMx is also expressed in postmitotic neurons, with prosurvival roles that are independent of its extensively described roles in carcinogenesis. We and others have shown a role for MDMx loss in neuronal death in vitro and in vivo in several neurodegenerative diseases. Further, we have recently shown that MDMx is targeted for proteolytic degradation by calcium-dependent proteases, calpains, in neurons in vitro, and that MDMx overexpression provided partial neuroprotection in a model of HIV-associated neurodegeneration. Here, we assessed whether amyloid ß (Aß)-induced MDMx degradation occurred in Alzheimer's Disease (AD) models. Our data shows an age-dependent reduction in MDMx levels in cholinergic neurons within the cortex of adult mice expressing the swedish mutant of the amyloid precursor protein, APP in the Tg2576 murine model of AD. In vitro, Aß treatment of primary cortical neurons led to the caspase-dependent MDMx degradation. Our findings suggest that MDMx degradation associated with neuronal death occurs via caspase activation in neurons, and that the progressive loss of MDMx protein represents a potential mechanism of Aß-induced neuronal death during disease progression in AD.


Assuntos
Caspases/metabolismo , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Envelhecimento/metabolismo , Peptídeos beta-Amiloides/farmacologia , Precursor de Proteína beta-Amiloide/genética , Animais , Células Cultivadas , Feminino , Camundongos , Camundongos Mutantes , Degeneração Neural/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fragmentos de Peptídeos/farmacologia
6.
Neuroreport ; 23(18): 1052-8, 2012 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-23111339

RESUMO

Necrosis and apoptosis are well established as two primary cell death pathways. Mixed neuroglial cultures are commonly used to study cell death mechanisms in neural cells. However, the ages of these cultures vary across studies and little attention has been paid to how cell death processes may change as the cultures mature. To clarify whether neuroglial culture age affects cell death mechanisms, we treated 1- and 3-week-old neuroglial cultures with either the excitotoxic stimulus, N-methyl-D-aspartate (NMDA), or with the oxidative stressor, hydrogen peroxide (H2O2). Although NMDA is known to be toxic only in cultures that are at least 2 weeks old, H2O2 is toxic in cultures of all ages. Here, we confirm that, in 1-week-old neuroglial cultures, NMDA does not induce toxicity, whereas H2O2 induces both calpain-mediated and caspase-mediated neuronal death. In 3-week-old cultures, both NMDA and H2O2 trigger calpain-mediated, but not caspase-mediated, neuronal death. Further, we observed a decrease in caspase-3 levels and an increase in calpain levels in untreated neuroglial cultures as they aged. The findings presented here show that neuronal cell death mechanisms vary with culture age and highlight the necessity of considering culture age when interpreting neural cell culture data.


Assuntos
Calpaína/fisiologia , Caspases/fisiologia , Córtex Cerebral/enzimologia , Fatores Etários , Animais , Animais Recém-Nascidos , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Células Cultivadas , Senescência Celular/efeitos dos fármacos , Córtex Cerebral/citologia , Córtex Cerebral/efeitos dos fármacos , Relação Dose-Resposta a Droga , Peróxido de Hidrogênio/farmacologia , N-Metilaspartato/farmacologia , Ratos , Ratos Sprague-Dawley
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