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1.
J Biol Chem ; 291(22): 11647-56, 2016 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-27008863

RESUMO

The biological underpinnings and the pathological lesions of psychiatric disorders are centuries-old questions that have yet to be understood. Recent studies suggest that schizophrenia and related disorders likely have their origins in perturbed neurodevelopment and can result from a large number of common genetic variants or multiple, individually rare genetic alterations. It is thus conceivable that key neurodevelopmental pathways underline the various genetic changes and the still unknown pathological lesions in schizophrenia. Here, we report that mice defective of the nicastrin subunit of γ-secretase in oligodendrocytes have hypomyelination in the central nervous system. These mice have altered dopamine signaling and display profound abnormal phenotypes reminiscent of schizophrenia. In addition, we identify an association of the nicastrin gene with a human schizophrenia cohort. These observations implicate γ-secretase and its mediated neurodevelopmental pathways in schizophrenia and provide support for the "myelination hypothesis" of the disease. Moreover, by showing that schizophrenia and obsessive-compulsive symptoms could be modeled in animals wherein a single genetic factor is altered, our work provides a biological basis that schizophrenia with obsessive-compulsive disorder is a distinct subtype of schizophrenia.


Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Comportamento Compulsivo , Glicoproteínas de Membrana/metabolismo , Bainha de Mielina/metabolismo , Oligodendroglia/metabolismo , Esquizofrenia/metabolismo , Secretases da Proteína Precursora do Amiloide/genética , Animais , Feminino , Humanos , Masculino , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Knockout , Pessoa de Meia-Idade , Esquizofrenia/genética
2.
J Neurosci ; 33(21): 9202-13, 2013 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-23699531

RESUMO

Progranulin (PGRN) is a secreted glycoprotein expressed in neurons and glia that is implicated in neuronal survival on the basis that mutations in the GRN gene causing haploinsufficiency result in a familial form of frontotemporal dementia (FTD). Recently, a direct interaction between PGRN and tumor necrosis factor receptors (TNFR I/II) was reported and proposed to be a mechanism by which PGRN exerts anti-inflammatory activity, raising the possibility that aberrant PGRN-TNFR interactions underlie the molecular basis for neuroinflammation in frontotemporal lobar degeneration pathogenesis. Here, we report that we find no evidence for a direct physical or functional interaction between PGRN and TNFRs. Using coimmunoprecipitation and surface plasmon resonance (SPR) we replicated the interaction between PGRN and sortilin and that between TNF and TNFRI/II, but not the interaction between PGRN and TNFRs. Recombinant PGRN or transfection of a cDNA encoding PGRN did not antagonize TNF-dependent NFκB, Akt, and Erk1/2 pathway activation; inflammatory gene expression; or secretion of inflammatory factors in BV2 microglia and bone marrow-derived macrophages (BMDMs). Moreover, PGRN did not antagonize TNF-induced cytotoxicity on dopaminergic neuroblastoma cells. Last, co-addition or pre-incubation with various N- or C-terminal-tagged recombinant PGRNs did not alter lipopolysaccharide-induced inflammatory gene expression or cytokine secretion in any cell type examined, including BMDMs from Grn+/- or Grn-/- mice. Therefore, the neuroinflammatory phenotype associated with PGRN deficiency in the CNS is not a direct consequence of the loss of TNF antagonism by PGRN, but may be a secondary response by glia to disrupted interactions between PGRN and Sortilin and/or other binding partners yet to be identified.


Assuntos
Citocinas/metabolismo , Regulação da Expressão Gênica/imunologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Receptores do Fator de Necrose Tumoral/metabolismo , Transdução de Sinais/fisiologia , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Análise de Variância , Animais , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Meios de Cultivo Condicionados/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Granulinas , Humanos , Imunoprecipitação , Peptídeos e Proteínas de Sinalização Intercelular/deficiência , Peptídeos e Proteínas de Sinalização Intercelular/genética , Isoquinolinas/metabolismo , Lipopolissacarídeos/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/imunologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/efeitos dos fármacos , Microglia/metabolismo , NF-kappa B/metabolismo , Progranulinas , Ligação Proteica/genética , Receptores do Fator de Necrose Tumoral/genética , Proteínas Recombinantes/farmacologia , Transdução de Sinais/efeitos dos fármacos , Ressonância de Plasmônio de Superfície , Transfecção
3.
J Biol Chem ; 288(12): 8627-8635, 2013 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-23364791

RESUMO

Progranulin is a secreted glycoprotein, and the GRN gene is mutated in some cases of frontotemporal dementia. Progranulin has also been implicated in cell growth, wound healing, inflammation, and cancer. We investigated the molecular nature of secreted progranulin and provide evidence that progranulin exists as a homodimer. Although recombinant progranulin has a molecular mass of ∼85 kDa by SDS-PAGE, it elutes in fractions corresponding to ∼170-180 kDa by gel-filtration chromatography. Additionally, recombinant progranulin can be intermolecularly cross-linked, yielding a complex corresponding to a dimer (∼180 kDa), and progranulins containing different epitope tags physically interact. In plasma, progranulin similarly forms complexes of ∼180-190 kDa. Although progranulin partially co-fractionated with high density lipoproteins (HDL) by gel-filtration chromatography, we found no evidence that progranulin in mouse or human plasma is a component of HDL either by ultracentrifugation or by lipid binding assays. We conclude that circulating progranulin exists as a dimer and is not likely a component of HDL.


Assuntos
Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Lipoproteínas HDL/sangue , Animais , Apolipoproteína A-I/metabolismo , Células HEK293 , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/sangue , Peptídeos e Proteínas de Sinalização Intercelular/isolamento & purificação , Lipoproteínas HDL/isolamento & purificação , Camundongos , Camundongos Knockout , Progranulinas , Domínios e Motivos de Interação entre Proteínas , Estrutura Quaternária de Proteína , Proteínas Recombinantes/sangue , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo
4.
Nat Commun ; 15(1): 6125, 2024 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-39033178

RESUMO

Heterozygous loss-of-function mutations in the GRN gene are a major cause of hereditary frontotemporal dementia. The mechanisms linking frontotemporal dementia pathogenesis to progranulin deficiency are not well understood, and there is currently no treatment. Our strategy to prevent the onset and progression of frontotemporal dementia in patients with GRN mutations is to utilize small molecule positive regulators of GRN expression to boost progranulin levels from the remaining functional GRN allele, thus restoring progranulin levels back to normal within the brain. This work describes a series of blood-brain-barrier-penetrant small molecules which significantly increase progranulin protein levels in human cellular models, correct progranulin protein deficiency in Grn+/- mouse brains, and reverse lysosomal proteome aberrations, a phenotypic hallmark of frontotemporal dementia, more efficiently than the previously described small molecule suberoylanilide hydroxamic acid. These molecules will allow further elucidation of the cellular functions of progranulin and its role in frontotemporal dementia and will also serve as lead structures for further drug development.


Assuntos
Demência Frontotemporal , Haploinsuficiência , Lisossomos , Progranulinas , Proteoma , Progranulinas/metabolismo , Progranulinas/genética , Animais , Humanos , Demência Frontotemporal/genética , Demência Frontotemporal/metabolismo , Demência Frontotemporal/tratamento farmacológico , Proteoma/metabolismo , Camundongos , Lisossomos/metabolismo , Lisossomos/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/efeitos dos fármacos , Vorinostat/farmacologia
5.
J Biol Chem ; 287(39): 32298-306, 2012 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-22859297

RESUMO

GRN mutations cause frontotemporal lobar degeneration with TDP-43-positive inclusions. The mechanism of pathogenesis is haploinsufficiency. Recently, homozygous GRN mutations were detected in two patients with neuronal ceroid lipofuscinosis, a lysosomal storage disease. It is unknown whether the pathogenesis of these two conditions is related. Progranulin is cleaved into smaller peptides called granulins. Progranulin and granulins are attributed with roles in cancer, inflammation, and neuronal physiology. Cell surface receptors for progranulin, but not granulin peptides, have been reported. Revealing the cell surface receptors and the intracellular functions of granulins and progranulin is crucial for understanding their contributions to neurodegeneration.


Assuntos
Degeneração Lobar Frontotemporal/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Mutação , Proteínas do Tecido Nervoso/metabolismo , Lipofuscinoses Ceroides Neuronais/metabolismo , Proteólise , Animais , Degeneração Lobar Frontotemporal/genética , Homozigoto , Humanos , Inflamação/genética , Inflamação/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/genética , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Proteínas do Tecido Nervoso/genética , Lipofuscinoses Ceroides Neuronais/genética , Progranulinas
6.
J Biol Chem ; 286(2): 1204-15, 2011 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-21051541

RESUMO

TAR DNA-binding protein 43 (TDP-43) is associated with a spectrum of neurodegenerative diseases. Although TDP-43 resembles heterogeneous nuclear ribonucleoproteins, its RNA targets and physiological protein partners remain unknown. Here we identify RNA targets of TDP-43 from cortical neurons by RNA immunoprecipitation followed by deep sequencing (RIP-seq). The canonical TDP-43 binding site (TG)(n) is 55.1-fold enriched, and moreover, a variant with adenine in the middle, (TG)(n)TA(TG)(m), is highly abundant among reads in our TDP-43 RIP-seq library. TDP-43 RNA targets can be divided into three different groups: those primarily binding in introns, in exons, and across both introns and exons. TDP-43 RNA targets are particularly enriched for Gene Ontology terms related to synaptic function, RNA metabolism, and neuronal development. Furthermore, TDP-43 binds to a number of RNAs encoding for proteins implicated in neurodegeneration, including TDP-43 itself, FUS/TLS, progranulin, Tau, and ataxin 1 and -2. We also identify 25 proteins that co-purify with TDP-43 from rodent brain nuclear extracts. Prominent among them are nuclear proteins involved in pre-mRNA splicing and RNA stability and transport. Also notable are two neuron-enriched proteins, methyl CpG-binding protein 2 and polypyrimidine tract-binding protein 2 (PTBP2). A PTBP2 consensus RNA binding motif is enriched in the TDP-43 RIP-seq library, suggesting that PTBP2 may co-regulate TDP-43 RNA targets. This work thus reveals the protein and RNA components of the TDP-43-containing ribonucleoprotein complexes and provides a framework for understanding how dysregulation of TDP-43 in RNA metabolism contributes to neurodegeneration.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Neurônios/fisiologia , Estabilidade de RNA/fisiologia , RNA Mensageiro/metabolismo , Proteinopatias TDP-43/metabolismo , Animais , Córtex Cerebral/citologia , Proteínas de Ligação a DNA/química , Biblioteca Gênica , Genômica , Células HeLa , Humanos , Camundongos , Peso Molecular , Neurônios/citologia , Proteômica , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , Ratos
7.
J Biol Chem ; 286(18): 16101-8, 2011 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-21454553

RESUMO

Progranulin (GRN) haploinsufficiency is a frequent cause of familial frontotemporal dementia, a currently untreatable progressive neurodegenerative disease. By chemical library screening, we identified suberoylanilide hydroxamic acid (SAHA), a Food and Drug Administration-approved histone deacetylase inhibitor, as an enhancer of GRN expression. SAHA dose-dependently increased GRN mRNA and protein levels in cultured cells and restored near-normal GRN expression in haploinsufficient cells from human subjects. Although elevation of secreted progranulin levels through a post-transcriptional mechanism has recently been reported, this is, to the best of our knowledge, the first report of a small molecule enhancer of progranulin transcription. SAHA has demonstrated therapeutic potential in other neurodegenerative diseases and thus holds promise as a first generation drug for the prevention and treatment of frontotemporal dementia.


Assuntos
Demência Frontotemporal/tratamento farmacológico , Inibidores de Histona Desacetilases/farmacologia , Ácidos Hidroxâmicos/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular/biossíntese , Transcrição Gênica/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Relação Dose-Resposta a Droga , Demência Frontotemporal/metabolismo , Células HEK293 , Humanos , Progranulinas , Vorinostat
8.
Biol Chem ; 393(7): 589-94, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22944662

RESUMO

From the earliest stages of embryogenesis and throughout life, transcriptional regulation is carefully orchestrated in order to generate, shape, and reshape the central nervous system (CNS). TAR DNA-binding protein 43 (TDP-43) is identified as a regulator of essential transcriptional events in the CNS. Evidence for its importance comes from the identification of TDP-43 protein aggregates and genetic mutations in patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Efforts are being made to learn more about the biological function of TDP-43 and gain a better understanding of its role in neurodegeneration. TDP-43 RNA targets and protein interactions have now been identified, and in vivo evidence shows that TDP-43 is essential in CNS development and function. This review will highlight aspects of these findings.


Assuntos
Encéfalo/fisiologia , Encéfalo/fisiopatologia , Proteínas de Ligação a DNA/metabolismo , Doenças Neurodegenerativas/metabolismo , Medula Espinal/fisiologia , Medula Espinal/fisiopatologia , Animais , Encéfalo/crescimento & desenvolvimento , Encéfalo/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Humanos , Doenças Neurodegenerativas/fisiopatologia , RNA/metabolismo , Ribonucleoproteínas/metabolismo , Medula Espinal/crescimento & desenvolvimento , Medula Espinal/metabolismo
9.
J Cardiovasc Pharmacol ; 60(3): 283-92, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22653417

RESUMO

The modulation of cardiac functions by nitric oxide (NO) was established. This study examined the influences of phosphodiesterase (PDE) inhibitors on the action of NO in the different regions of the rat heart. NO donor diethylamine nonoate (DEA/NO) (0.1-100 µM) decreased functions of the right atrium. DEA/NO-induced depression of the developed tension of the right atrium was inhibited by [erythro-9-(2-hydroxy-3-nonyl)adenine] (PDE2 inhibitor), augmented by milrinone (PDE3 inhibitor), and upturned by rolipram (PDE4 inhibitor). A DEA/NO-induced decrease in the resting tension was inhibited by vinpocetine (PDE1 inhibitor) and [erythro-9-(2-hydroxy-3-nonyl)adenine] but reversed by rolipram. The decreased sinus rate by DEA/NO was prevented by vinpocetine and rolipram. DEA/NO increased cyclic guanosine monophosphate and cyclic adenosine monophosphate (cAMP) concentrations in the right atrium, and rolipram enhanced increased cAMP level. DEA/NO had no effect on the contraction of the papillary muscle. However, unchanged contraction under DEA/NO stimulation was decreased by vinpocetine, milrinone, and rolipram. DEA/NO increased cyclic guanosine monophosphate concentration but has no effect on cAMP in the papillary muscle. However, in the presence of vinpocetine and milrinone, DEA/NO reduced cAMP level. The PDE5 inhibitor sildenafil has no effect on DEA/NO actions. This study indicates that a variety of PDE activities in different regions of the rat heart shapes the action of NO on the myocardium.


Assuntos
Coração/efeitos dos fármacos , Coração/fisiologia , Miocárdio/enzimologia , Óxido Nítrico/antagonistas & inibidores , Inibidores de Fosfodiesterase/farmacologia , Diester Fosfórico Hidrolases/metabolismo , Animais , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Feminino , Masculino , Óxido Nítrico/fisiologia , Doadores de Óxido Nítrico/farmacologia , Técnicas de Cultura de Órgãos , Piperazinas/farmacologia , Purinas/farmacologia , Ratos , Ratos Wistar , Rolipram/farmacologia , Citrato de Sildenafila , Sulfonas/farmacologia , Resultado do Tratamento
10.
Transl Psychiatry ; 12(1): 139, 2022 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-35379782

RESUMO

Major depressive disorder (MDD) is a common, disabling, and heterogeneous condition that responds unpredictably to current treatments. We previously showed an association between depressive symptoms and plasma concentrations of two cholesterol precursors, desmosterol and 7-dehydrocholesterol (7DHC). Here, we measured total cholesterol and sterol concentrations with mass spectrometry in postmortem brain samples from depressed and control subjects. Mean (±SEM) desmosterol concentration was 8.9 ± 0.97 ng/mg in the depressed versus 10.7 ± 0.72 ng/mg in the control group. The mean of the posterior probability distribution for the difference in desmosterol concentration between the two groups was 2.36 (95% highest density interval [HDI] 0.59-4.17). Mean 7DHC concentrations, 12.5 ± 4.1 ng/mg in the depressed versus 5.4 ± 0.74 ng/mg in the control group, were unlikely to be different (95% HDI, [-1.37-0.34]). We found that presence of trazodone in the peri-mortem toxicology screen accounted for the observed difference in desmosterol concentrations. We also observed extremely high 7DHC levels in all 4 subjects who had taken trazodone. Trazodone has been recently found to inhibit 7-dehydrocholesterol reductase and alter sterol concentrations in rodents, cell culture, human fibroblasts, and blood. In this study, we demonstrate for the first time that trazodone alters human brain sterol composition. Given congenital deficiency of 7-dehydrocholesterol reductase results in Smith-Lemli-Opitz syndrome, our findings support the hypothesis that this commonly used medication may have previously unappreciated risks.


Assuntos
Transtorno Depressivo Maior , Trazodona , Encéfalo , Desidrocolesteróis , Desmosterol , Humanos , Trazodona/farmacologia
11.
Eur J Pharmacol ; 844: 118-129, 2019 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-30529467

RESUMO

Phosphodiesterase enzymes (PDEs) are responsible for the adjustment of cyclic nucleotide levels. Alterations in PDE expressions in different tissues cause conflicts between functional and clinical effects of PDE inhibitors. Therefore, the aim of this study was to investigate the gene and protein expressions and the functional role of PDEs in atrium and ventricle of rat heart. The expressions of PDEs were examined in cardiac intact tissues and enzymatically isolated cells. The effects of PDE1-5 inhibitors (vinpocetine, EHNA, milrinone, rolipram, sildenafil, and IBMX) on basal and isoprenaline-stimulated contractions and sinus rate were recorded in the isolated spontaneously beating right atrium and electrically stimulated left papillary muscles. The mRNA and protein levels of PDEs were significantly different in atrial and ventricular intact tissues and isolated myocytes. Atrial contractions were increased with vinpocetine while suppressed by EHNA, milrinone, rolipram, sildenafil and IBMX. Milrinone, sildenafil and IBMX increased the heart rate whereas vinpocetine caused negative chronotropy. Papillary muscle contractions have been increased only with the vinpocetine and IBMX. Both the expression and the action of PDE-1-5 show atrial and ventricular differences. Therefore, these differences should be taken into account in the experimental or therapeutic approaches of the heart.


Assuntos
Função Atrial , Músculos Papilares/fisiologia , Diester Fosfórico Hidrolases/fisiologia , Função Ventricular , Animais , Função Atrial/efeitos dos fármacos , Feminino , Átrios do Coração/metabolismo , Ventrículos do Coração/metabolismo , Masculino , Miócitos Cardíacos/fisiologia , Inibidores de Fosfodiesterase/farmacologia , Ratos Wistar , Função Ventricular/efeitos dos fármacos
12.
PLoS One ; 12(9): e0184382, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28886149

RESUMO

Convergent evidence strongly suggests major depressive disorder is heterogeneous in its etiology and clinical characteristics. Depression biomarkers hold potential for identifying etiological subtypes, improving diagnostic accuracy, predicting treatment response, and personalization of treatment. Human plasma contains numerous sterols that have not been systematically studied. Changes in cholesterol concentrations have been implicated in suicide and depression, suggesting plasma sterols may be depression biomarkers. Here, we investigated associations between plasma levels of 34 sterols (measured by mass spectrometry) and scores on the Quick Inventory of Depressive Symptomatology-Self Report (QIDS-SR16) scale in 3117 adult participants in the Dallas Heart Study, an ethnically diverse, population-based cohort. We built a random forest model using feature selection from a pool of 43 variables including demographics, general health indicators, and sterol concentrations. This model comprised 19 variables, 13 of which were sterol concentrations, and explained 15.5% of the variation in depressive symptoms. Desmosterol concentrations below the fifth percentile (1.9 ng/mL, OR 1.9, 95% CI 1.2-2.9) were significantly associated with depressive symptoms of at least moderate severity (QIDS-SR16 score ≥10.5). This is the first study reporting a novel association between plasma concentrations cholesterol precursors and depressive symptom severity.


Assuntos
Depressão/sangue , Depressão/diagnóstico , Esteróis/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores , Depressão/epidemiologia , Feminino , Humanos , Lipoproteínas/sangue , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Razão de Chances , Vigilância da População , Índice de Gravidade de Doença , Fatores Socioeconômicos , Texas , Adulto Jovem
13.
Cell Rep ; 20(11): 2565-2574, 2017 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-28903038

RESUMO

Defective lysosomal function defines many neurodegenerative diseases, such as neuronal ceroid lipofuscinoses (NCL) and Niemann-Pick type C (NPC), and is implicated in Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD-TDP) with progranulin (PGRN) deficiency. Here, we show that PGRN is involved in lysosomal homeostasis and lipid metabolism. PGRN deficiency alters lysosome abundance and morphology in mouse neurons. Using an unbiased lipidomic approach, we found that brain lipid composition in humans and mice with PGRN deficiency shows disease-specific differences that distinguish them from normal and other pathologic groups. PGRN loss leads to an accumulation of polyunsaturated triacylglycerides, as well as a reduction of diacylglycerides and phosphatidylserines in fibroblast and enriched lysosome lipidomes. Transcriptomic analysis of PGRN-deficient mouse brains revealed distinct expression patterns of lysosomal, immune-related, and lipid metabolic genes. These findings have implications for the pathogenesis of FTLD-TDP due to PGRN deficiency and suggest lysosomal dysfunction as an underlying mechanism.


Assuntos
Peptídeos e Proteínas de Sinalização Intercelular/deficiência , Metabolismo dos Lipídeos , Metaboloma , Transcriptoma/genética , Animais , Análise Discriminante , Embrião de Mamíferos/patologia , Feminino , Fibroblastos/metabolismo , Fibroblastos/patologia , Perfilação da Expressão Gênica , Granulinas , Hipocampo/patologia , Hipocampo/ultraestrutura , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Lipídeos/isolamento & purificação , Fígado/metabolismo , Fígado/patologia , Lisossomos/metabolismo , Lisossomos/ultraestrutura , Camundongos , Camundongos Mutantes , Neurônios/metabolismo , Neurônios/ultraestrutura , Progranulinas
14.
Nat Commun ; 7: 11992, 2016 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-27356620

RESUMO

Progranulin (GRN) loss-of-function mutations leading to progranulin protein (PGRN) haploinsufficiency are prevalent genetic causes of frontotemporal dementia. Reports also indicated PGRN-mediated neuroprotection in models of Alzheimer's and Parkinson's disease; thus, increasing PGRN levels is a promising therapeutic for multiple disorders. To uncover novel PGRN regulators, we linked whole-genome sequence data from 920 individuals with plasma PGRN levels and identified the prosaposin (PSAP) locus as a new locus significantly associated with plasma PGRN levels. Here we show that both PSAP reduction and overexpression lead to significantly elevated extracellular PGRN levels. Intriguingly, PSAP knockdown increases PGRN monomers, whereas PSAP overexpression increases PGRN oligomers, partly through a protein-protein interaction. PSAP-induced changes in PGRN levels and oligomerization replicate in human-derived fibroblasts obtained from a GRN mutation carrier, further supporting PSAP as a potential PGRN-related therapeutic target. Future studies should focus on addressing the relevance and cellular mechanism by which PGRN oligomeric species provide neuroprotection.


Assuntos
Demência Frontotemporal/genética , Peptídeos e Proteínas de Sinalização Intercelular/genética , Saposinas/genética , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Animais , Demência Frontotemporal/metabolismo , Técnicas de Silenciamento de Genes , Haploinsuficiência , Células HeLa , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Camundongos , Camundongos Knockout , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Polimorfismo de Nucleotídeo Único , Progranulinas , Mapas de Interação de Proteínas
15.
Brain Res ; 1462: 16-25, 2012 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-22405725

RESUMO

The RNA-binding protein TDP-43 is strongly linked to neurodegeneration. Not only are mutations in the gene encoding TDP-43 associated with ALS and FTLD, but this protein is also a major constituent of pathological intracellular inclusions in these diseases. Recent studies have significantly expanded our understanding of TDP-43 physiology. TDP-43 is now known to play important roles in neuronal RNA metabolism. It binds to and regulates the splicing and stability of numerous RNAs encoding proteins involved in neuronal development, synaptic function and neurodegeneration. Thus, a loss of these essential functions is an attractive hypothesis regarding the role of TDP-43 in neurodegeneration. Moreover, TDP-43 is an aggregation-prone protein and, given the role of toxic protein aggregates in neurodegeneration, a toxic gain-of-function mechanism is another rational hypothesis. Importantly, ALS related mutations modulate the propensity of TDP-43 to aggregate in cell culture. Several recent studies have documented that cytoplasmic TDP-43 aggregates co-localize with stress granule markers. Stress granules are cytoplasmic inclusions that repress translation of a subset of RNAs in times of cellular stress, and several proteins implicated in neurodegeneration (i.e. Ataxin-2 and SMN) interact with stress granules. Thus, understanding the interplay between TDP-43 aggregation, stress granules and the effect of ALS-associated TDP-43 mutations may be the key to understanding the role of TDP-43 in neurodegeneration. We propose two models of TDP-43 aggregate formation. The "independent model" stipulates that TDP-43 aggregation is independent of stress granule formation, in contrast to the "precursor model" which presents the idea that stress granule formation contributes to a TDP-43 aggregate "seed" and that chronic stress leads to concentration-dependent TDP-43 aggregation. This article is part of a Special Issue entitled: RNA-Binding Proteins.


Assuntos
Grânulos Citoplasmáticos/patologia , Proteínas de Ligação a DNA/metabolismo , Doenças Neurodegenerativas/patologia , Proteinopatias TDP-43/patologia , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Animais , Proteínas de Ligação a DNA/genética , Degeneração Lobar Frontotemporal/genética , Degeneração Lobar Frontotemporal/patologia , Humanos , Corpos de Inclusão/patologia , RNA/metabolismo , Transdução de Sinais/genética
16.
Mol Cell Biol ; 31(5): 1098-108, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21173160

RESUMO

TDP-43, or TAR DNA-binding protein 43, is a pathological marker of a spectrum of neurodegenerative disorders, including amyotrophic lateral sclerosis and frontotemporal lobar degeneration with ubiquitin-positive inclusions. TDP-43 is an RNA/DNA-binding protein implicated in transcriptional and posttranscriptional regulation. Recent work also suggests that TDP-43 associates with cytoplasmic stress granules, which are transient structures that form in response to stress. In this study, we establish sorbitol as a novel physiological stressor that directs TDP-43 to stress granules in Hek293T cells and primary cultured glia. We quantify the association of TDP-43 with stress granules over time and show that stress granule association and size are dependent on the glycine-rich region of TDP-43, which harbors the majority of pathogenic mutations. Moreover, we establish that cells harboring wild-type and mutant TDP-43 have distinct stress responses: mutant TDP-43 forms significantly larger stress granules, and is incorporated into stress granules earlier, than wild-type TDP-43; in striking contrast, wild-type TDP-43 forms more stress granules over time, but the granule size remains relatively unchanged. We propose that mutant TDP-43 alters stress granule dynamics, which may contribute to the progression of TDP-43 proteinopathies.


Assuntos
Grânulos Citoplasmáticos/metabolismo , Proteínas de Ligação a DNA/metabolismo , Estresse Oxidativo , Sorbitol/farmacologia , Sequência de Aminoácidos , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/metabolismo , Animais , Bioensaio , Linhagem Celular , Células Cultivadas , Proteínas de Ligação a DNA/genética , Humanos , Camundongos , Dados de Sequência Molecular , Mutação , Neuroglia/efeitos dos fármacos , Neuroglia/metabolismo , Pressão Osmótica , Ratos , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/metabolismo
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