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1.
PLoS Biol ; 17(2): e3000134, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30735499

RESUMO

Microglia are resident immune cells that play critical roles in maintaining the normal physiology of the central nervous system (CNS). Remarkably, microglia have an intrinsic capacity to repopulate themselves after acute ablation. However, the underlying mechanisms that drive such restoration remain elusive. Here, we characterized microglial repopulation both spatially and temporally following removal via treatment with the colony stimulating factor 1 receptor (CSF1R) inhibitor PLX5622. We show that microglia were replenished via self-renewal, with no contribution from nonmicroglial lineages, including Nestin+ progenitors and the circulating myeloid population. Interestingly, spatial analyses with dual-color labeling revealed that newborn microglia recolonized the parenchyma by forming distinctive clusters that maintained stable territorial boundaries over time, indicating the proximal expansive nature of adult microgliogenesis and the stability of microglia tiling. Temporal transcriptome profiling at different repopulation stages revealed that adult newborn microglia gradually regain steady-state maturity from an immature state that is reminiscent of the neonatal stage and follow a series of maturation programs, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation, interferon immune activation, and apoptosis. Importantly, we show that the restoration of microglial homeostatic density requires NF-κB signaling as well as apoptotic egress of excessive cells. In summary, our study reports key events that take place from microgliogenesis to homeostasis reestablishment.


Assuntos
Envelhecimento/genética , Encéfalo/metabolismo , Homeostase/genética , Microglia/metabolismo , NF-kappa B/genética , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/genética , Envelhecimento/metabolismo , Animais , Animais Recém-Nascidos , Apoptose/efeitos dos fármacos , Apoptose/genética , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Interferons/genética , Interferons/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/citologia , Microglia/efeitos dos fármacos , NF-kappa B/metabolismo , Nestina/genética , Nestina/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Neurogênese/efeitos dos fármacos , Neurogênese/genética , Compostos Orgânicos/toxicidade , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/antagonistas & inibidores , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/metabolismo , Receptores do Fator de Crescimento Derivado de Plaquetas/genética , Receptores do Fator de Crescimento Derivado de Plaquetas/metabolismo , Regeneração/genética , Transdução de Sinais , Transcriptoma
2.
Proc Natl Acad Sci U S A ; 115(48): E11388-E11396, 2018 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-30413620

RESUMO

Located within the brain's ventricles, the choroid plexus produces cerebrospinal fluid and forms an important barrier between the central nervous system and the blood. For unknown reasons, the choroid plexus produces high levels of the protein klotho. Here, we show that these levels naturally decline with aging. Depleting klotho selectively from the choroid plexus via targeted viral vector-induced knockout in Klothoflox/flox mice increased the expression of multiple proinflammatory factors and triggered macrophage infiltration of this structure in young mice, simulating changes in unmanipulated old mice. Wild-type mice infected with the same Cre recombinase-expressing virus did not show such alterations. Experimental depletion of klotho from the choroid plexus enhanced microglial activation in the hippocampus after peripheral injection of mice with lipopolysaccharide. In primary cultures, klotho suppressed thioredoxin-interacting protein-dependent activation of the NLRP3 inflammasome in macrophages by enhancing fibroblast growth factor 23 signaling. We conclude that klotho functions as a gatekeeper at the interface between the brain and immune system in the choroid plexus. Klotho depletion in aging or disease may weaken this barrier and promote immune-mediated neuropathogenesis.


Assuntos
Envelhecimento/imunologia , Encéfalo/imunologia , Plexo Corióideo/imunologia , Glucuronidase/imunologia , Envelhecimento/genética , Animais , Feminino , Glucuronidase/genética , Hipocampo/imunologia , Humanos , Proteínas Klotho , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/imunologia
3.
Proc Natl Acad Sci U S A ; 115(40): 10172-10177, 2018 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-30232263

RESUMO

Alzheimer's disease (AD), the most common form of dementia, is characterized by the abnormal accumulation of amyloid plaques and hyperphosphorylated tau aggregates, as well as microgliosis. Hemizygous missense variants in Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) are associated with elevated risk for developing late-onset AD. These variants are hypothesized to result in loss of function, mimicking TREM2 haploinsufficiency. However, the consequences of TREM2 haploinsufficiency on tau pathology and microglial function remain unknown. We report the effects of partial and complete loss of TREM2 on microglial function and tau-associated deficits. In vivo imaging revealed that microglia from aged TREM2-haploinsufficient mice show a greater impairment in their injury response compared with microglia from aged TREM2-KO mice. In transgenic mice expressing mutant human tau, TREM2 haploinsufficiency, but not complete loss of TREM2, increased tau pathology. In addition, whereas complete TREM2 deficiency protected against tau-mediated microglial activation and atrophy, TREM2 haploinsufficiency elevated expression of proinflammatory markers and exacerbated atrophy at a late stage of disease. The differential effects of partial and complete loss of TREM2 on microglial function and tau pathology provide important insights into the critical role of TREM2 in AD pathogenesis.


Assuntos
Doença de Alzheimer , Haploinsuficiência , Hemizigoto , Glicoproteínas de Membrana , Microglia/metabolismo , Mutação de Sentido Incorreto , Receptores Imunológicos , Envelhecimento/genética , Envelhecimento/metabolismo , Envelhecimento/patologia , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Animais , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Microglia/patologia , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo
4.
Hum Mol Genet ; 27(2): 322-337, 2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29161404

RESUMO

Members of the conserved ubiquilin (UBQLN) family of ubiquitin (Ub) chaperones harbor an antipodal UBL (Ub-like)-UBA (Ub-associated) domain arrangement and participate in proteasome and autophagosome-mediated protein degradation. Mutations in a proline-rich-repeat region (PRR) of UBQLN2 cause amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD); however, neither the normal functions of the PRR nor impacts of ALS-associated mutations within it are well understood. In this study, we show that ALS mutations perturb UBQLN2 solubility and folding in a mutation-specific manner. Biochemical impacts of ALS mutations were additive, transferable to UBQLN1, and resulted in enhanced Ub association. A Drosophila melanogaster model for UBQLN2-associated ALS revealed that both wild-type and ALS-mutant UBQLN2 alleles disrupted Ub homeostasis; however, UBQLN2ALS mutants exhibited age-dependent aggregation and caused toxicity phenotypes beyond those seen for wild-type UBQLN2. Although UBQLN2 toxicity was not correlated with aggregation in the compound eye, aggregation-prone UBQLN2 mutants elicited climbing defects and neuromuscular junctions (NMJ) abnormalities when expressed in neurons. An UBA domain mutation that abolished Ub binding also diminished UBQLN2 toxicity, implicating Ub binding in the underlying pathomechanism. We propose that ALS-associated mutations in UBQLN2 disrupt folding and that both aggregated species and soluble oligomers instigate neuron autonomous toxicity through interference with Ub homeostasis.


Assuntos
Esclerose Lateral Amiotrófica/genética , Proteínas de Transporte/genética , Proteínas de Ciclo Celular/genética , Mutação , Ubiquitinas/genética , Proteínas Adaptadoras de Transdução de Sinal , Sequência de Aminoácidos , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologia , Animais , Animais Geneticamente Modificados , Proteínas Relacionadas à Autofagia , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ligação a DNA/genética , Modelos Animais de Doenças , Proteínas de Drosophila , Drosophila melanogaster , Demência Frontotemporal/genética , Frequência do Gene , Genes Reguladores , Células HEK293 , Humanos , Corpos de Inclusão/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteólise , Ubiquitinas/metabolismo
5.
Proc Natl Acad Sci U S A ; 114(19): 5029-5034, 2017 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-28438992

RESUMO

Frontotemporal dementia (FTD) is the second most common dementia before 65 years of age. Haploinsufficiency in the progranulin (GRN) gene accounts for 10% of all cases of familial FTD. GRN mutation carriers have an increased risk of autoimmune disorders, accompanied by elevated levels of tissue necrosis factor (TNF) α. We examined behavioral alterations related to obsessive-compulsive disorder (OCD) and the role of TNFα and related signaling pathways in FTD patients with GRN mutations and in mice lacking progranulin (PGRN). We found that patients and mice with GRN mutations displayed OCD and self-grooming (an OCD-like behavior in mice), respectively. Furthermore, medium spiny neurons in the nucleus accumbens, an area implicated in development of OCD, display hyperexcitability in PGRN knockout mice. Reducing levels of TNFα in PGRN knockout mice abolished excessive self-grooming and the associated hyperexcitability of medium spiny neurons of the nucleus accumbens. In the brain, PGRN is highly expressed in microglia, which are a major source of TNFα. We therefore deleted PGRN specifically in microglia and found that it was sufficient to induce excessive grooming. Importantly, excessive grooming in these mice was prevented by inactivating nuclear factor κB (NF-κB) in microglia/myeloid cells. Our findings suggest that PGRN deficiency leads to excessive NF-κB activation in microglia and elevated TNFα signaling, which in turn lead to hyperexcitability of medium spiny neurons and OCD-like behavior.


Assuntos
Demência Frontotemporal/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/deficiência , Microglia/metabolismo , NF-kappa B/metabolismo , Transtorno Obsessivo-Compulsivo/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Idoso , Idoso de 80 Anos ou mais , Animais , Modelos Animais de Doenças , Feminino , Demência Frontotemporal/genética , Demência Frontotemporal/patologia , Granulinas , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Masculino , Camundongos , Camundongos Knockout , Microglia/patologia , NF-kappa B/genética , Transtorno Obsessivo-Compulsivo/genética , Transtorno Obsessivo-Compulsivo/patologia , Progranulinas , Fator de Necrose Tumoral alfa/genética
6.
Hum Mol Genet ; 24(3): 757-72, 2015 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-25281658

RESUMO

Pathological aggregation and mutation of the 43-kDa TAR DNA-binding protein (TDP-43) are strongly implicated in the pathogenesis amyotrophic lateral sclerosis and frontotemporal lobar degeneration. TDP-43 neurotoxicity has been extensively modeled in mice, zebrafish, Caenorhabditis elegans and Drosophila, where selective expression of TDP-43 in motoneurons led to paralysis and premature lethality. Through a genetic screen aimed to identify genetic modifiers of TDP-43, we found that the Drosophila dual leucine kinase Wallenda (Wnd) and its downstream kinases JNK and p38 influenced TDP-43 neurotoxicity. Reducing Wnd gene dosage or overexpressing its antagonist highwire partially rescued TDP-43-associated premature lethality. Downstream of Wnd, the JNK and p38 kinases played opposing roles in TDP-43-associated neurodegeneration. LOF alleles of the p38b gene as well as p38 inhibitors diminished TDP-43-associated premature lethality, whereas p38b GOF caused phenotypic worsening. In stark contrast, disruptive alleles of Basket (Bsk), the Drosophila homologue of JNK, exacerbated longevity shortening, whereas overexpression of Bsk extended lifespan. Among possible mechanisms, we found motoneuron-directed expression of TDP-43 elicited oxidative stress and innate immune gene activation that were exacerbated by p38 GOF and Bsk LOF, respectively. A key pathologic role for innate immunity in TDP-43-associated neurodegeneration was further supported by the finding that genetic suppression of the Toll/Dif and Imd/Relish inflammatory pathways dramatically extended lifespan of TDP-43 transgenic flies. We propose that oxidative stress and neuroinflammation are intrinsic components of TDP-43-associated neurodegeneration and that the balance between cytoprotective JNK and cytotoxic p38 signaling dictates phenotypic outcome to TDP-43 expression in Drosophila.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Proteinopatias TDP-43/imunologia , Proteinopatias TDP-43/patologia , Animais , Animais Geneticamente Modificados , Drosophila melanogaster/imunologia , Genes Letais , Humanos , Imunidade Inata , MAP Quinase Quinase Quinases/metabolismo , Sistema de Sinalização das MAP Quinases , Estresse Oxidativo , Proteinopatias TDP-43/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
7.
Biochem Biophys Res Commun ; 462(1): 1-7, 2015 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-25839658

RESUMO

Escherichia Coli GnsA is a regulator of phosphatidylethanolamine synthesis and functions as a suppressor of both a secG null mutation and fabA6 mutations. GnsA may also be a toxin with the cognate antitoxin YmcE. Here we report the crystal structure of GnsA to 1.8 Å. GnsA forms a V shaped hairpin structure that is tightly associated into a homodimer. Our comprehensive structural study suggests that GnsA is structurally similar to an outer membrane protein, suggesting a function of protein binding.


Assuntos
Proteínas de Escherichia coli/química , Multimerização Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , Eletroforese em Gel de Poliacrilamida , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Ligação Proteica
8.
Hum Mol Genet ; 21(22): 4845-56, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-22872699

RESUMO

Cytosolic aggregation of the nuclear RNA-binding protein (RBP) TDP-43 (43 kDa TAR DNA-binding domain protein) is a suspected direct or indirect cause of motor neuron deterioration in amyotrophic lateral sclerosis (ALS). In this study, we implemented a high-content, genome-wide RNAi screen to identify pathways controlling TDP-43 nucleocytoplasmic shuttling. We identified ∼60 genes whose silencing increased the cytosolic localization of TDP-43, including nuclear pore complex components and regulators of G2/M cell cycle transition. In addition, we identified the type 1 inositol-1,4,5-trisphosphate (IP3) receptor (ITPR1), an IP3-gated, endoplasmic reticulum (ER)-resident Ca(2+) channel, as a strong modulator of TDP-43 nucleocytoplasmic shuttling. Knockdown or chemical inhibition of ITPR1 induced TDP-43 nuclear export in immortalized cells and primary neurons and strongly potentiated the recruitment of TDP-43 to Ubiquilin-positive autophagosomes, suggesting that diminished ITPR1 function leads to autophagosomal clearance of TDP-43. The functional significance of the TDP-43-ITPR1 genetic interaction was tested in Drosophila, where mutant alleles of ITPR1 were found to significantly extended lifespan and mobility of flies expressing TDP-43 under a motor neuron driver. These combined findings implicate IP3-gated Ca(2+) as a key regulator of TDP-43 nucleoplasmic shuttling and proteostasis and suggest pharmacologic inhibition of ITPR1 as a strategy to combat TDP-43-induced neurodegeneration in vivo.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Proteínas de Ligação a DNA/toxicidade , Drosophila/genética , Drosophila/metabolismo , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Células HeLa , Ensaios de Triagem em Larga Escala , Humanos , Receptores de Inositol 1,4,5-Trifosfato/genética , Masculino , Mutação , Fagossomos/metabolismo , Transporte Proteico , Interferência de RNA
9.
Nat Neurosci ; 26(3): 416-429, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36635496

RESUMO

Loss-of-function variants of TREM2 are associated with increased risk of Alzheimer's disease (AD), suggesting that activation of this innate immune receptor may be a useful therapeutic strategy. Here we describe a high-affinity human TREM2-activating antibody engineered with a monovalent transferrin receptor (TfR) binding site, termed antibody transport vehicle (ATV), to facilitate blood-brain barrier transcytosis. Upon peripheral delivery in mice, ATV:TREM2 showed improved brain biodistribution and enhanced signaling compared to a standard anti-TREM2 antibody. In human induced pluripotent stem cell (iPSC)-derived microglia, ATV:TREM2 induced proliferation and improved mitochondrial metabolism. Single-cell RNA sequencing and morphometry revealed that ATV:TREM2 shifted microglia to metabolically responsive states, which were distinct from those induced by amyloid pathology. In an AD mouse model, ATV:TREM2 boosted brain microglial activity and glucose metabolism. Thus, ATV:TREM2 represents a promising approach to improve microglial function and treat brain hypometabolism found in patients with AD.


Assuntos
Doença de Alzheimer , Células-Tronco Pluripotentes Induzidas , Humanos , Animais , Camundongos , Microglia , Barreira Hematoencefálica , Distribuição Tecidual , Anticorpos , Encéfalo , Modelos Animais de Doenças , Glicoproteínas de Membrana , Receptores Imunológicos/genética
10.
J Biol Chem ; 286(14): 12766-74, 2011 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-21324900

RESUMO

The mammalian circadian clock component PERIOD2 (PER2) plays a critical role in circadian rhythm entrainment. Recently, a missense mutation at a putative phosphorylation site in hPER2, Ser-662, was identified in patients that suffer from familial advanced sleep phase syndrome (FASPS). Patients with FASPS display abnormal sleep-wake patterns characterized by a lifelong pattern of sleep onset in the early evening and offset in the early morning. Although the phosphorylation of PER2 is strongly implied from functional studies, it has not been possible to study the site-specific phosphorylation of PER2 on Ser-662, and the biochemical functions of this residue are unclear. Here, we used phospho-specific antibodies to show that PER2 is phosphorylated on Ser-662 and flanking casein kinase (CK) sites in vivo. The phosphorylation of PER2 was carried out by the combined activities of casein kinase 1δ (CK1 δ) and casein kinase 1ε (CK1ε) and was antagonized by protein phosphatase 1. PER2 phosphorylation was rapidly induced in response to circadian entrainment of mammalian cell lines and occurred in both cytosolic and nuclear compartments. Importantly, we found that the pool of Ser-662-phosphorylated PER2 proteins was more stable than the pool of total PER2 molecules, implying that the FASPS phosphorylation cluster antagonizes PER2 degradation. Consistent with this idea, a Ser-662→Ala mutation that abrogated PER2 phosphorylation significantly reduced its half-life, whereas a phosphomimetic Ser-662→Asp substitution led to an elevation in half-life. Our combined findings provide new insights into PER2 regulation and the biochemical basis of FASPS.


Assuntos
Caseína Quinase I/metabolismo , Proteínas Circadianas Period/metabolismo , Transtornos do Sono do Ritmo Circadiano/metabolismo , Animais , Linhagem Celular , Ritmo Circadiano/genética , Humanos , Immunoblotting , Camundongos , Células NIH 3T3 , Fosfoproteínas Fosfatases/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo
11.
Nat Commun ; 13(1): 1969, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35413950

RESUMO

Activation of microglia is a prominent pathological feature in tauopathies, including Alzheimer's disease. How microglia activation contributes to tau toxicity remains largely unknown. Here we show that nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, activated by tau, drives microglial-mediated tau propagation and toxicity. Constitutive activation of microglial NF-κB exacerbated, while inactivation diminished, tau seeding and spreading in young PS19 mice. Inhibition of NF-κB activation enhanced the retention while reduced the release of internalized pathogenic tau fibrils from primary microglia and rescued microglial autophagy deficits. Inhibition of microglial NF-κB in aged PS19 mice rescued tau-mediated learning and memory deficits, restored overall transcriptomic changes while increasing neuronal tau inclusions. Single cell RNA-seq revealed that tau-associated disease states in microglia were diminished by NF-κB inactivation and further transformed by constitutive NF-κB activation. Our study establishes a role for microglial NF-κB signaling in mediating tau spreading and toxicity in tauopathy.


Assuntos
Microglia , NF-kappa B , Tauopatias , Proteínas tau , Animais , Camundongos , Microglia/metabolismo , Microglia/patologia , NF-kappa B/metabolismo , Tauopatias/metabolismo , Tauopatias/patologia , Proteínas tau/metabolismo
12.
Nat Neurosci ; 25(9): 1149-1162, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35953545

RESUMO

Microglia are emerging as key drivers of neurological diseases. However, we lack a systematic understanding of the underlying mechanisms. Here, we present a screening platform to systematically elucidate functional consequences of genetic perturbations in human induced pluripotent stem cell-derived microglia. We developed an efficient 8-day protocol for the generation of microglia-like cells based on the inducible expression of six transcription factors. We established inducible CRISPR interference and activation in this system and conducted three screens targeting the 'druggable genome'. These screens uncovered genes controlling microglia survival, activation and phagocytosis, including neurodegeneration-associated genes. A screen with single-cell RNA sequencing as the readout revealed that these microglia adopt a spectrum of states mirroring those observed in human brains and identified regulators of these states. A disease-associated state characterized by osteopontin (SPP1) expression was selectively depleted by colony-stimulating factor-1 (CSF1R) inhibition. Thus, our platform can systematically uncover regulators of microglial states, enabling their functional characterization and therapeutic targeting.


Assuntos
Células-Tronco Pluripotentes Induzidas , Microglia , Encéfalo/metabolismo , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Microglia/metabolismo , Fagocitose/genética
13.
Nucleic Acids Res ; 37(13): 4371-84, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19465398

RESUMO

HMGA proteins are not translated in normal human somatic cells, but are present in high copy numbers in pluripotent embryonic stem cells and most neoplasias. Correlations between the degree of malignancy, patient prognostic index and HMGA levels have been firmly established. Intriguingly, HMGA2 is also found in rare tumor-inducing cells which are resistant to chemotherapy. Here, we demonstrate that HMGA1a/b and HMGA2 possess intrinsic dRP and AP site cleavage activities, and that lysines and arginines in the AT-hook DNA-binding domains function as nucleophiles. We also show that HMGA2 can be covalently trapped at genomic abasic sites in cancer cells. By employing a variety of cell-based assays, we provide evidence that the associated lyase activities promote cellular resistance against DNA damage that is targeted by base excision repair (BER) pathways, and that this protection directly correlates with the level of HMGA2 expression. In addition, we demonstrate an interaction between human AP endonuclease 1 and HMGA2 in cancer cells, which supports our conclusion that HMGA2 can be incorporated into the cellular BER machinery. Our study thus identifies an unexpected role for HMGA2 in DNA repair in cancer cells which has important clinical implications for disease diagnosis and therapy.


Assuntos
Antineoplásicos/toxicidade , Dano ao DNA , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Proteína HMGA2/metabolismo , Neoplasias/enzimologia , Fósforo-Oxigênio Liases/metabolismo , Motivos AT-Hook , Linhagem Celular Tumoral , Reparo do DNA , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/química , Resistencia a Medicamentos Antineoplásicos , Genoma Humano , Proteína HMGA2/química , Humanos , Hidroxiureia/toxicidade , Metanossulfonato de Metila/toxicidade , Mutagênicos/toxicidade , Neoplasias/tratamento farmacológico , Neoplasias/genética
14.
Elife ; 92020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-33054973

RESUMO

Microglia are the resident myeloid cells in the central nervous system (CNS). The majority of microglia rely on CSF1R signaling for survival. However, a small subset of microglia in mouse brains can survive without CSF1R signaling and reestablish the microglial homeostatic population after CSF1R signaling returns. Using single-cell transcriptomic analysis, we characterized the heterogeneous microglial populations under CSF1R inhibition, including microglia with reduced homeostatic markers and elevated markers of inflammatory chemokines and proliferation. Importantly, MAC2/Lgals3 was upregulated under CSF1R inhibition, and shared striking similarities with microglial progenitors in the yolk sac and immature microglia in early embryos. Lineage-tracing studies revealed that these MAC2+ cells were of microglial origin. MAC2+ microglia were also present in non-treated adult mouse brains and exhibited immature transcriptomic signatures indistinguishable from those that survived CSF1R inhibition, supporting the notion that MAC2+ progenitor-like cells are present among adult microglia.


Assuntos
Encéfalo/metabolismo , Galectina 3/genética , Camundongos/fisiologia , Microglia/metabolismo , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/genética , Transdução de Sinais/genética , Animais , Feminino , Galectina 3/metabolismo , Homeostase , Masculino , Camundongos/genética , Camundongos Endogâmicos C57BL , Receptores de Fator Estimulador das Colônias de Granulócitos e Macrófagos/metabolismo
15.
Sci Rep ; 10(1): 13688, 2020 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-32792571

RESUMO

Patients with frontotemporal dementia (FTD) resulting from granulin (GRN) haploinsufficiency have reduced levels of progranulin and exhibit dysregulation in inflammatory and lysosomal networks. Microglia produce high levels of progranulin, and reduction of progranulin in microglia alone is sufficient to recapitulate inflammation, lysosomal dysfunction, and hyperproliferation in a cell-autonomous manner. Therefore, targeting microglial dysfunction caused by progranulin insufficiency represents a potential therapeutic strategy to manage neurodegeneration in FTD. Limitations of current progranulin-enhancing strategies necessitate the discovery of new targets. To identify compounds that can reverse microglial defects in Grn-deficient mouse microglia, we performed a compound screen coupled with high throughput sequencing to assess key transcriptional changes in inflammatory and lysosomal pathways. Positive hits from this initial screen were then further narrowed down based on their ability to rescue cathepsin activity, a critical biochemical readout of lysosomal capacity. The screen identified nor-binaltorphimine dihydrochloride (nor-BNI) and dibutyryl-cAMP, sodium salt (DB-cAMP) as two phenotypic modulators of progranulin deficiency. In addition, nor-BNI and DB-cAMP also rescued cell cycle abnormalities in progranulin-deficient cells. These data highlight the potential of a transcription-based platform for drug screening, and advance two novel lead compounds for FTD.


Assuntos
Bucladesina/farmacologia , Cisteína Proteases/metabolismo , Demência Frontotemporal/genética , Perfilação da Expressão Gênica/métodos , Microglia/citologia , Naltrexona/análogos & derivados , Progranulinas/deficiência , Animais , Ciclo Celular/efeitos dos fármacos , Células Cultivadas , Modelos Animais de Doenças , Demência Frontotemporal/tratamento farmacológico , Demência Frontotemporal/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Técnicas de Inativação de Genes , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lisossomos/genética , Lisossomos/metabolismo , Camundongos , Microglia/efeitos dos fármacos , Microglia/metabolismo , Modelos Biológicos , Naltrexona/farmacologia , Análise de Sequência de RNA , Bibliotecas de Moléculas Pequenas/farmacologia
16.
Nat Neurosci ; 23(2): 167-171, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31873194

RESUMO

Sex is a key modifier of neurological disease outcomes. Microglia are implicated in neurological diseases and modulated by microRNAs, but it is unknown whether microglial microRNAs have sex-specific influences on disease. We show in mice that microglial microRNA expression differs in males and females and that loss of microRNAs leads to sex-specific changes in the microglial transcriptome and tau pathology. These findings suggest that microglial microRNAs influence tau pathogenesis in a sex-specific manner.


Assuntos
Encéfalo/patologia , MicroRNAs/metabolismo , Microglia/metabolismo , Caracteres Sexuais , Tauopatias/patologia , Animais , Encéfalo/metabolismo , Feminino , Masculino , Camundongos , Microglia/patologia , Tauopatias/metabolismo , Transcriptoma , Proteínas tau/metabolismo
17.
Acta Crystallogr F Struct Biol Commun ; 70(Pt 3): 335-8, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24598921

RESUMO

The bacterial type VI secretion system (T6SS), a dynamic organelle, participates in microbial competition by transporting toxic effector molecules to neighbouring cells to kill competitors. TsiV3, a recently defined T6SS immunity protein in Vibrio cholerae, possesses self-protection against killing by T6SS predatory cells by directly binding to and inhibiting their effector protein VgrG-3. Structural information about TsiV3 could help to illuminate its specific mechanism. In this study, TsiV3 from V. cholerae was cloned, expressed and crystallized and single-crystal X-ray diffraction data sets were collected to a resolution of 2.55 Å. Specifically, the crystal belonged to space group P212121, with unit-cell parameters a = 73.3, b = 78.12, c = 106.18 Å. Matthews coefficient calculations indicated that the crystal may contain six TsiV3 molecules in one asymmetric unit, with a VM value of 2.25 Å(3) Da(-1) and a solvent content of 45.42%.


Assuntos
Proteínas de Bactérias/química , Vibrio cholerae , Proteínas de Bactérias/isolamento & purificação , Sistemas de Secreção Bacterianos , Cromatografia de Afinidade , Cristalização , Cristalografia por Raios X
18.
PLoS One ; 8(2): e57214, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23468938

RESUMO

Cytosolic aggregation of the nuclear RNA-binding protein TDP-43 is a histopathologic signature of degenerating neurons in amyotrophic lateral sclerosis (ALS), and mutations in the TARDBP gene encoding TDP-43 cause dominantly inherited forms of this condition. To understand the relationship between TDP-43 misregulation and neurotoxicity, we and others have used Drosophila as a model system, in which overexpression of either wild-type TDP-43 or its ALS-associated mutants in neurons is sufficient to induce neurotoxicity, paralysis, and early death. Using microarrays, we have examined gene expression patterns that accompany TDP-43-induced neurotoxicity in the fly system. Constitutive expression of TDP-43 in the Drosophila compound eye elicited widespread gene expression changes, with strong upregulation of cell cycle regulatory genes and genes functioning in the Notch intercellular communication pathway. Inducible expression of TDP-43 specifically in neurons elicited significant expression differences in a more restricted set of genes. Genes that were upregulated in both paradigms included SpindleB and the Notch target Hey, which appeared to be a direct TDP-43 target. Mutations that diminished activity of Notch or disrupted the function of downstream Notch target genes extended the lifespan of TDP-43 transgenic flies, suggesting that Notch activation was deleterious in this model. Finally, we showed that mutation of the nucleoporin Nup50 increased the lifespan of TDP-43 transgenic flies, suggesting that nuclear events contribute to TDP-43-dependent neurotoxicity. The combined findings identified pathways whose deregulation might contribute to TDP-43-induced neurotoxicity in Drosophila.


Assuntos
Proteínas de Ligação a DNA/toxicidade , Drosophila/efeitos dos fármacos , Sistema Nervoso/efeitos dos fármacos , Proteínas de Ligação a RNA/toxicidade , Animais , Animais Geneticamente Modificados , Apoptose , Proteínas de Ligação a DNA/genética , Drosophila/genética , Sistema Nervoso/metabolismo , Proteínas de Ligação a RNA/genética
19.
PLoS One ; 5(8): e12173, 2010 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-20730097

RESUMO

Activating transcription factor 1 (ATF1) and the closely related proteins CREB (cyclic AMP resonse element binding protein) and CREM (cyclic AMP response element modulator) constitute a subfamily of bZIP transcription factors that play critical roles in the regulation of cellular growth, metabolism, and survival. Previous studies demonstrated that CREB is phosphorylated on a cluster of conserved Ser residues, including Ser-111 and Ser-121, in response to DNA damage through the coordinated actions of the ataxia-telangiectasia-mutated (ATM) protein kinase and casein kinases 1 and 2 (CK1/2). Here, we show that DNA damage-induced phosphorylation by ATM is a general feature of CREB and ATF1. ATF1 harbors a conserved ATM/CK cluster that is constitutively and stoichiometrically phosphorylated by CK1 and CK2 in asynchronously growing cells. Exposure to DNA damage further induced ATF1 phosphorylation on Ser-51 by ATM in a manner that required prior phosphorylation of the upstream CK residues. Hyperphosphorylated ATF1 showed a 4-fold reduced affinity for CREB-binding protein. We further show that PP2A, in conjunction with its targeting subunit B56gamma, antagonized ATM and CK1/2-dependent phosphorylation of CREB and ATF1 in cellulo. Finally, we show that CK sites in CREB are phosphorylated during cellular growth and that phosphorylation of these residues reduces the threshold of DNA damage required for ATM-dependent phosphorylation of the inhibitory Ser-121 residue. These studies define overlapping and distinct modes of CREB and ATF1 regulation by phosphorylation that may ensure concerted changes in gene expression mediated by these factors.


Assuntos
Fator 1 Ativador da Transcrição/metabolismo , Sequência Conservada , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Dano ao DNA , Proteína Fosfatase 2/metabolismo , Fator 1 Ativador da Transcrição/química , Sequência de Aminoácidos , Animais , Proteínas Mutadas de Ataxia Telangiectasia , Proteína de Ligação a CREB/química , Proteína de Ligação a CREB/metabolismo , Caseína Quinase I/metabolismo , Caseína Quinase II/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proliferação de Células , Meios de Cultivo Condicionados/farmacologia , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Evolução Molecular , Regulação Enzimológica da Expressão Gênica , Células HeLa , Humanos , Camundongos , Dados de Sequência Molecular , Fosforilação/efeitos dos fármacos , Fosforilação/efeitos da radiação , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Estrutura Terciária de Proteína , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Serina/metabolismo , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo
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