Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
1.
EMBO J ; 28(4): 372-82, 2009 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-19153604

RESUMO

Deubiquitinating enzymes (DUBs) control the ubiquitination status of proteins in various cellular pathways. Regulation of the activity of DUBs, which is critically important to cellular homoeostasis, can be achieved at the level of gene expression, protein complex formation, or degradation. Here, we report that ubiquitination also directly regulates the activity of a DUB, ataxin-3, a polyglutamine disease protein implicated in protein quality control pathways. Ubiquitination enhances ubiquitin (Ub) chain cleavage by ataxin-3, but does not alter its preference for K63-linked Ub chains. In cells, ubiquitination of endogenous ataxin-3 increases when the proteasome is inhibited, when excess Ub is present, or when the unfolded protein response is induced, suggesting that the cellular functions of ataxin-3 in protein quality control are modulated through ubiquitination. Ataxin-3 is the first reported DUB in which ubiquitination directly regulates catalytic activity. We propose a new function for protein ubiquitination in regulating the activity of certain DUBs and perhaps other enzymes.


Assuntos
Proteínas do Tecido Nervoso/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Repressoras/metabolismo , Ubiquitina/fisiologia , Animais , Ataxina-3 , Encéfalo/metabolismo , Células COS , Catálise , Chlorocebus aethiops , Regulação da Expressão Gênica , Homeostase , Humanos , Doença de Machado-Joseph/metabolismo , Modelos Biológicos , Desnaturação Proteica , Dobramento de Proteína , Processamento de Proteína Pós-Traducional , Ubiquitina/química
2.
Life Sci Alliance ; 6(8)2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37221017

RESUMO

mTORC1 is the key rheostat controlling the cellular metabolic state. Of the various inputs to mTORC1, the most potent effector of intracellular nutrient status is amino acid supply. Despite an established role for MAP4K3 in promoting mTORC1 activation in the presence of amino acids, the signaling pathway by which MAP4K3 controls mTORC1 activation remains unknown. Here, we examined the process of MAP4K3 regulation of mTORC1 and found that MAP4K3 represses the LKB1-AMPK pathway to achieve robust mTORC1 activation. When we sought the regulatory link between MAP4K3 and LKB1 inhibition, we discovered that MAP4K3 physically interacts with the master nutrient regulatory factor sirtuin-1 (SIRT1) and phosphorylates SIRT1 to repress LKB1 activation. Our results reveal the existence of a novel signaling pathway linking amino acid satiety with MAP4K3-dependent suppression of SIRT1 to inactivate the repressive LKB1-AMPK pathway and thereby potently activate the mTORC1 complex to dictate the metabolic disposition of the cell.


Assuntos
Proteínas Quinases Ativadas por AMP , Sirtuína 1 , Transdução de Sinais , Aminoácidos , Alvo Mecanístico do Complexo 1 de Rapamicina
4.
Nat Med ; 24(4): 427-437, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29505030

RESUMO

Spinal bulbar muscular atrophy (SBMA) is a motor neuron disease caused by toxic gain of function of the androgen receptor (AR). Previously, we found that co-regulator binding through the activation function-2 (AF2) domain of AR is essential for pathogenesis, suggesting that AF2 may be a potential drug target for selective modulation of toxic AR activity. We screened previously identified AF2 modulators for their ability to rescue toxicity in a Drosophila model of SBMA. We identified two compounds, tolfenamic acid (TA) and 1-[2-(4-methylphenoxy)ethyl]-2-[(2-phenoxyethyl)sulfanyl]-1H-benzimidazole (MEPB), as top candidates for rescuing lethality, locomotor function and neuromuscular junction defects in SBMA flies. Pharmacokinetic analyses in mice revealed a more favorable bioavailability and tissue retention of MEPB compared with TA in muscle, brain and spinal cord. In a preclinical trial in a new mouse model of SBMA, MEPB treatment yielded a dose-dependent rescue from loss of body weight, rotarod activity and grip strength. In addition, MEPB ameliorated neuronal loss, neurogenic atrophy and testicular atrophy, validating AF2 modulation as a potent androgen-sparing strategy for SBMA therapy.


Assuntos
Atrofia Muscular Espinal/patologia , Degeneração Neural/patologia , Receptores Androgênicos/química , Receptores Androgênicos/metabolismo , Animais , Benzimidazóis/farmacologia , Benzimidazóis/uso terapêutico , Proteínas Correpressoras/metabolismo , Modelos Animais de Doenças , Drosophila melanogaster , Células HEK293 , Humanos , Masculino , Camundongos Transgênicos , Atrofia Muscular Espinal/tratamento farmacológico , Degeneração Neural/tratamento farmacológico , Fenótipo , Projetos Piloto , Domínios Proteicos , Expansão das Repetições de Trinucleotídeos/genética , ortoaminobenzoatos/farmacologia , ortoaminobenzoatos/uso terapêutico
5.
Neuron ; 81(3): 536-543, 2014 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-24507191

RESUMO

The RNA-binding protein TDP-43 regulates RNA metabolism at multiple levels, including transcription, RNA splicing, and mRNA stability. TDP-43 is a major component of the cytoplasmic inclusions characteristic of amyotrophic lateral sclerosis and some types of frontotemporal lobar degeneration. The importance of TDP-43 in disease is underscored by the fact that dominant missense mutations are sufficient to cause disease, although the role of TDP-43 in pathogenesis is unknown. Here we show that TDP-43 forms cytoplasmic mRNP granules that undergo bidirectional, microtubule-dependent transport in neurons in vitro and in vivo and facilitate delivery of target mRNA to distal neuronal compartments. TDP-43 mutations impair this mRNA transport function in vivo and in vitro, including in stem cell-derived motor neurons from ALS patients bearing any one of three different TDP-43 ALS-causing mutations. Thus, TDP-43 mutations that cause ALS lead to partial loss of a novel cytoplasmic function of TDP-43.


Assuntos
Esclerose Lateral Amiotrófica/patologia , Transporte Axonal/genética , Proteínas de Ligação a DNA/genética , Neurônios Motores/metabolismo , Mutação/genética , RNA Mensageiro/metabolismo , Esclerose Lateral Amiotrófica/genética , Animais , Animais Geneticamente Modificados , Células Cultivadas , Córtex Cerebral/citologia , Drosophila , Proteínas de Drosophila/genética , Humanos , Fator 4 Semelhante a Kruppel , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Proteínas Luminescentes/genética , Camundongos , Mitocôndrias/metabolismo , Neurônios Motores/ultraestrutura , Fator 3 de Transcrição de Octâmero/genética , Fator 3 de Transcrição de Octâmero/metabolismo , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo
6.
Nat Neurosci ; 17(5): 664-666, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24686783

RESUMO

MATR3 is an RNA- and DNA-binding protein that interacts with TDP-43, a disease protein linked to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Using exome sequencing, we identified mutations in MATR3 in ALS kindreds. We also observed MATR3 pathology in ALS-affected spinal cords with and without MATR3 mutations. Our data provide more evidence supporting the role of aberrant RNA processing in motor neuron degeneration.


Assuntos
Esclerose Lateral Amiotrófica/genética , Saúde da Família , Predisposição Genética para Doença/genética , Mutação/genética , Proteínas Associadas à Matriz Nuclear/genética , Proteínas de Ligação a RNA/genética , Idoso , Idoso de 80 Anos ou mais , Esclerose Lateral Amiotrófica/patologia , Biologia Computacional , Análise Mutacional de DNA , Proteínas de Ligação a DNA/metabolismo , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Exame Neurológico , Proteínas Associadas à Matriz Nuclear/metabolismo , Proteínas de Ligação a RNA/metabolismo , Medula Espinal/metabolismo , Medula Espinal/patologia
7.
Neuron ; 78(1): 65-80, 2013 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-23498974

RESUMO

Mutations in VCP cause multisystem degeneration impacting the nervous system, muscle, and/or bone. Patients may present with ALS, Parkinsonism, frontotemporal dementia, myopathy, Paget's disease, or a combination of these. The disease mechanism is unknown. We developed a Drosophila model of VCP mutation-dependent degeneration. The phenotype is reminiscent of PINK1 and parkin mutants, including a pronounced mitochondrial defect. Indeed, VCP interacts genetically with the PINK1/parkin pathway in vivo. Paradoxically, VCP complements PINK1 deficiency but not parkin deficiency. The basis of this paradox is resolved by mechanistic studies in vitro showing that VCP recruitment to damaged mitochondria requires Parkin-mediated ubiquitination of mitochondrial targets. VCP recruitment coincides temporally with mitochondrial fission, and VCP is required for proteasome-dependent degradation of Mitofusins in vitro and in vivo. Further, VCP and its adaptor Npl4/Ufd1 are required for clearance of damaged mitochondria via the PINK1/Parkin pathway, and this is impaired by pathogenic mutations in VCP.


Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas de Drosophila/metabolismo , Mitocôndrias/genética , Neurônios/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Proteínas Adaptadoras de Transporte Vesicular , Adenosina Trifosfatases/genética , Animais , Animais Geneticamente Modificados , Carbonil Cianeto m-Clorofenil Hidrazona/farmacologia , Proteínas de Ciclo Celular/genética , Células Cultivadas , Drosophila , Proteínas de Drosophila/genética , Embrião de Mamíferos , Inibidores Enzimáticos/farmacologia , GTP Fosfo-Hidrolases/metabolismo , Gânglios Espinais/citologia , Regulação da Expressão Gênica/genética , Proteínas de Choque Térmico HSP72/genética , Humanos , Imunoprecipitação , Técnicas In Vitro , Peptídeos e Proteínas de Sinalização Intracelular , Leupeptinas/farmacologia , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Microscopia Eletrônica de Transmissão , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Mutação/genética , Junção Neuromuscular/genética , Junção Neuromuscular/metabolismo , Neurônios/ultraestrutura , Proteínas Nucleares/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Fosfatases/genética , Proteínas/metabolismo , Ionóforos de Próton/farmacologia , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/farmacologia , Fatores de Tempo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Transfecção , Ubiquitina-Proteína Ligases/genética , Ubiquitinação/genética , Proteína com Valosina
8.
J Biol Chem ; 283(39): 26436-43, 2008 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-18599482

RESUMO

Ubiquitin chain complexity in cells is likely regulated by a diverse set of deubiquitinating enzymes (DUBs) with distinct ubiquitin chain preferences. Here we show that the polyglutamine disease protein, ataxin-3, binds and cleaves ubiquitin chains in a manner suggesting that it functions as a mixed linkage, chain-editing enzyme. Ataxin-3 cleaves ubiquitin chains through its amino-terminal Josephin domain and binds ubiquitin chains through a carboxyl-terminal cluster of ubiquitin interaction motifs neighboring the pathogenic polyglutamine tract. Ataxin-3 binds both Lys(48)- or Lys(63)-linked chains yet preferentially cleaves Lys(63) linkages. Ataxin-3 shows even greater activity toward mixed linkage polyubiquitin, cleaving Lys(63) linkages in chains that contain both Lys(48) and Lys(63) linkages. The ubiquitin interaction motifs regulate the specificity of this activity by restricting what can be cleaved by the protease domain, demonstrating that linkage specificity can be determined by elements outside the catalytic domain of a DUB. These findings establish ataxin-3 as a novel DUB that edits topologically complex chains.


Assuntos
Encefalopatias Metabólicas Congênitas/enzimologia , Transtornos Heredodegenerativos do Sistema Nervoso/enzimologia , Proteínas do Tecido Nervoso/metabolismo , Proteínas Nucleares/metabolismo , Peptídeos/metabolismo , Proteínas Repressoras/metabolismo , Ubiquitina Tiolesterase/metabolismo , Ubiquitina/metabolismo , Motivos de Aminoácidos/genética , Ataxina-3 , Encefalopatias Metabólicas Congênitas/genética , Linhagem Celular , Transtornos Heredodegenerativos do Sistema Nervoso/genética , Humanos , Proteínas do Tecido Nervoso/genética , Proteínas Nucleares/genética , Peptídeos/genética , Estrutura Terciária de Proteína/genética , Proteínas Repressoras/genética , Ubiquitina/genética , Ubiquitina Tiolesterase/genética
9.
J Biol Chem ; 282(40): 29348-58, 2007 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-17693639

RESUMO

Ataxin-3, a deubiquitinating enzyme, is the disease protein in spinocerebellar ataxia type 3, one of many neurodegenerative disorders caused by polyglutamine expansion. Little is known about the cellular regulation of ataxin-3. This is an important issue, since growing evidence links disease protein context to pathogenesis in polyglutamine disorders. Expanded ataxin-3, for example, is more neurotoxic in fruit fly models when its active site cysteine is mutated (1). We therefore sought to determine the influence of ataxin-3 enzymatic activity on various cellular properties. Here we present evidence that the catalytic activity of ataxin-3 regulates its cellular turnover, ubiquitination, and subcellular distribution. Cellular protein levels of catalytically inactive ataxin-3 were much higher than those of active ataxin-3, in part reflecting slower degradation. In vitro studies revealed that inactive ataxin-3 was more slowly degraded by the proteasome and that this degradation occurred independent of ubiquitination. Slower degradation of inactive ataxin-3 correlated with reduced interaction with the proteasome shuttle protein, VCP/p97. Enzymatically active ataxin-3 also showed a greater tendency to concentrate in the nucleus, where it colocalized with the proteasome in subnuclear foci. Taken together, these and other findings suggest that the catalytic activity of this disease-linked deubiquitinating enzyme regulates several of its cellular properties, which in turn may influence disease pathogenesis.


Assuntos
Proteínas do Tecido Nervoso/metabolismo , Proteínas Nucleares/metabolismo , Peptídeos/genética , Peptídeos/metabolismo , Proteínas Repressoras/metabolismo , Animais , Ataxina-3 , Células COS , Catálise , Linhagem Celular , Chlorocebus aethiops , Glutationa Transferase/metabolismo , Humanos , Modelos Biológicos , Proteínas do Tecido Nervoso/fisiologia , Proteínas Nucleares/fisiologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Repressoras/fisiologia , Ubiquitina/química , Ubiquitina/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA