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1.
EMBO J ; 38(14): e101293, 2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31304631

RESUMO

Whether epigenetic factors such as DNA methylation and microRNAs interact to control adult hippocampal neurogenesis is not fully understood. Here, we show that Down syndrome critical region 1 (DSCR1) protein plays a key role in adult hippocampal neurogenesis by modulating two epigenetic factors: TET1 and miR-124. We find that DSCR1 mutant mice have impaired adult hippocampal neurogenesis. DSCR1 binds to TET1 introns to regulate splicing of TET1, thereby modulating TET1 level. Furthermore, TET1 controls the demethylation of the miRNA-124 promoter to modulate miR-124 expression. Correcting the level of TET1 in DSCR1 knockout mice is sufficient to prevent defective adult neurogenesis. Importantly, restoring DSCR1 level in a Down syndrome mouse model effectively rescued adult neurogenesis and learning and memory deficits. Our study reveals that DSCR1 plays a critical upstream role in epigenetic regulation of adult neurogenesis and provides insights into potential therapeutic strategy for treating cognitive defects in Down syndrome.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Síndrome de Down/genética , Hipocampo/citologia , MicroRNAs/genética , Oxigenases de Função Mista/genética , Proteínas Musculares/metabolismo , Proteínas Proto-Oncogênicas/genética , Splicing de RNA , Animais , Células Cultivadas , Proteínas de Ligação a DNA/genética , Modelos Animais de Doenças , Síndrome de Down/metabolismo , Epigênese Genética , Técnicas de Silenciamento de Genes , Hipocampo/metabolismo , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Proteínas Musculares/genética , Mutação , Neurogênese , Regiões Promotoras Genéticas
2.
BMC Biol ; 20(1): 12, 2022 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-34996455

RESUMO

BACKGROUND: The establishment and maintenance of functional neural connections relies on appropriate distribution and localization of mitochondria in neurites, as these organelles provide essential energy and metabolites. In particular, mitochondria are transported to axons and support local energy production to maintain energy-demanding neuronal processes including axon branching, growth, and regeneration. Additionally, local protein synthesis is required for structural and functional changes in axons, with nuclear-encoded mitochondrial mRNAs having been found localized in axons. However, it remains unclear whether these mRNAs are locally translated and whether the potential translated mitochondrial proteins are involved in the regulation of mitochondrial functions in axons. Here, we aim to further understand the purpose of such compartmentalization by focusing on the role of mitochondrial initiation factor 3 (mtIF3), whose nuclear-encoded transcripts have been shown to be present in axonal growth cones. RESULTS: We demonstrate that brain-derived neurotrophic factor (BDNF) induces local translation of mtIF3 mRNA in axonal growth cones. Subsequently, mtIF3 protein is translocated into axonal mitochondria and promotes mitochondrial translation as assessed by our newly developed bimolecular fluorescence complementation sensor for the assembly of mitochondrial ribosomes. We further show that BDNF-induced axonal growth requires mtIF3-dependent mitochondrial translation in distal axons. CONCLUSION: We describe a previously unknown function of mitochondrial initiation factor 3 (mtIF3) in axonal protein synthesis and development. These findings provide insight into the way neurons adaptively control mitochondrial physiology and axonal development via local mtIF3 translation.


Assuntos
Axônios , Fator Neurotrófico Derivado do Encéfalo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Neurônios/fisiologia , Fatores de Iniciação de Peptídeos/metabolismo , Biossíntese de Proteínas
3.
EMBO J ; 37(5)2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29440227

RESUMO

In neuronal development, dynamic rearrangement of actin promotes axonal growth cone extension, and spatiotemporal translation of local mRNAs in response to guidance cues directs axonal growth cone steering, where cofilin plays a critical role. While regulation of cofilin activity is well studied, regulatory mechanism for cofilin mRNA translation in neurons is unknown. In eukaryotic cells, proteins can be synthesized by cap-dependent or cap-independent mechanism via internal ribosome entry site (IRES)-mediated translation. IRES-mediated translation has been reported in various pathophysiological conditions, but its role in normal physiological environment is poorly understood. Here, we report that 5'UTR of cofilin mRNA contains an IRES element, and cofilin is predominantly translated by IRES-mediated mechanism in neurons. Furthermore, we show that IRES-mediated translation of cofilin is required for both axon extension and axonal growth cone steering. Our results provide new insights into the function of IRES-mediated translation in neuronal development.


Assuntos
Axônios/fisiologia , Cofilina 1/genética , Cones de Crescimento/fisiologia , Sítios Internos de Entrada Ribossomal/genética , Neurogênese/genética , Regiões 5' não Traduzidas/genética , Animais , Encéfalo/embriologia , Sistemas CRISPR-Cas , Linhagem Celular , Proliferação de Células/genética , Cofilina 1/metabolismo , Camundongos , Biossíntese de Proteínas/genética , RNA Mensageiro/genética
4.
J Pathol ; 255(3): 296-310, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34312845

RESUMO

Highly developed meningeal lymphatics remove waste products from the brain. Disruption of meningeal lymphatic vessels in a mouse model of amyloid pathology (5XFAD) accelerates the accumulation of amyloid plaques in the meninges and brain, and causes learning and memory deficits, suggesting that clearance of toxic wastes by lymphatic vessels plays a key role in neurodegenerative diseases. Here, we discovered that DSCR1 (Down syndrome critical region 1, known also as RCAN1, regulator of calcineurin 1) facilitates the drainage of waste products by increasing the coverage of dorsal meningeal lymphatic vessels. Furthermore, upregulation of DSCR1 in 5XFAD mice diminishes Aß pathology in the brain and improves memory defects. Surgical ligation of cervical lymphatic vessels afferent to dcLN blocks the beneficial effects of DSCR1 on Aß accumulation and cognitive function. Interestingly, intracerebroventricular delivery of AAV1-DSCR1 to 5XFAD mice is sufficient to rebuild the meningeal lymphatic system and re-establish cognitive performance. Collectively, our data indicate that DSCR1 facilitates the growth of dorsal meningeal lymphatics to improve drainage efficiency and protect against Alzheimer's disease (AD) pathologies, further highlighting that improving meningeal lymphatic function is a feasible treatment strategy for AD. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.


Assuntos
Doença de Alzheimer/patologia , Proteínas de Ligação ao Cálcio/metabolismo , Dura-Máter/metabolismo , Vasos Linfáticos , Proteínas Musculares/metabolismo , Placa Amiloide/patologia , Animais , Sistema Glinfático/metabolismo , Camundongos , Camundongos Transgênicos , Regulação para Cima
5.
Proc Natl Acad Sci U S A ; 116(32): 16074-16079, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31332012

RESUMO

Translocation of the endoplasmic reticulum (ER) and mitochondria to the site of axon injury has been shown to facilitate axonal regeneration; however, the existence and physiological importance of ER-mitochondria tethering in the injured axons are unknown. Here, we show that a protein linking ER to mitochondria, the glucose regulated protein 75 (Grp75), is locally translated at axon injury site following axotomy, and that overexpression of Grp75 in primary neurons increases ER-mitochondria tethering to promote regrowth of injured axons. We find that increased ER-mitochondria tethering elevates mitochondrial Ca2+ and enhances ATP generation, thereby promoting regrowth of injured axons. Furthermore, intrathecal delivery of lentiviral vector encoding Grp75 to an animal with sciatic nerve crush injury enhances axonal regeneration and functional recovery. Together, our findings suggest that increased ER-mitochondria tethering at axonal injury sites may provide a therapeutic strategy for axon regeneration.


Assuntos
Axônios/metabolismo , Retículo Endoplasmático/metabolismo , Mitocôndrias/metabolismo , Regeneração Nervosa , Trifosfato de Adenosina/metabolismo , Animais , Cálcio/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Biossíntese de Proteínas , Nervo Isquiático/lesões , Nervo Isquiático/patologia , Canal de Ânion 1 Dependente de Voltagem/metabolismo
6.
J Neurosci ; 38(20): 4666-4677, 2018 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-29686046

RESUMO

Mitochondrial Ca2+ uptake is gated by the mitochondrial calcium uniplex, which is comprised of mitochondrial calcium uniporter (MCU), the Ca2+ pore-forming subunit of the complex, and its regulators. Ca2+ influx through MCU affects both mitochondrial function and movement in neurons, but its direct role in mitochondrial movement has not been explored. In this report, we show a link between MCU and Miro1, a membrane protein known to regulate mitochondrial movement. We find that MCU interacts with Miro1 through MCU's N-terminal domain, previously thought to be the mitochondrial targeting sequence. Our results show that the N-terminus of MCU has a transmembrane domain that traverses the outer mitochondrial membrane, which is dispensable for MCU localization into mitochondria. However, this domain is required for Miro1 interaction and is critical for Miro1 directed movement. Together, our findings reveal Miro1 as a new component of the MCU complex, and that MCU is an important regulator of mitochondrial transport.SIGNIFICANCE STATEMENT Mitochondrial calcium level is critical for mitochondrial metabolic activity and mitochondrial transport in neurons. While it has been established that calcium influx into mitochondria is modulated by mitochondrial calcium uniporter (MCU) complex, how MCU regulates mitochondrial movement still remains unclear. Here, we discover that the N-terminus of MCU plays a different role than previously thought; it is not required for mitochondrial targeting but is essential for interaction with Miro1, an outer mitochondrial membrane protein important for mitochondrial movement. Furthermore, we show that MCU-Miro1 interaction is required to maintain mitochondrial transport. Our data identify that Miro1 is a novel component of the mitochondrial calcium uniplex and demonstrate that coupling between MCU and Miro1 as a novel mechanism modulating both mitochondrial Ca2+ uptake and mitochondrial transport.


Assuntos
Canais de Cálcio/fisiologia , Mitocôndrias/fisiologia , Proteínas Mitocondriais/metabolismo , Neurônios/fisiologia , Proteínas rho de Ligação ao GTP/fisiologia , Animais , Axônios/metabolismo , Transporte Biológico Ativo/genética , Transporte Biológico Ativo/fisiologia , Cálcio/metabolismo , Canais de Cálcio/genética , Canais de Cálcio/metabolismo , Células Cultivadas , Feminino , Cinética , Camundongos , Camundongos Endogâmicos C57BL , Membranas Mitocondriais/fisiologia , Gravidez , Proteínas rho de Ligação ao GTP/genética
7.
EMBO J ; 31(18): 3655-66, 2012 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-22863780

RESUMO

Most common genetic factors known to cause intellectual disability are Down syndrome and Fragile X syndrome. However, the underlying cellular and molecular mechanisms of intellectual disability remain unclear. Recently, dendritic spine dysmorphogenesis and impaired local protein synthesis are posited to contribute to the cellular mechanisms of intellectual disability. Here, we show that Down syndrome critical region1 (DSCR1) interacts with Fragile X mental retardation protein (FMRP) and regulates both dendritic spine morphogenesis and local protein synthesis. Interestingly, decreasing the level of FMRP restores the DSCR1-induced changes in dendritic spine morphology. Our results imply that DSCR1 is a novel regulator of FMRP and that Fragile X syndrome and Down syndrome may share disturbances in common pathways that regulate dendritic spine morphology and local protein synthesis.


Assuntos
Espinhas Dendríticas/metabolismo , Proteína do X Frágil da Deficiência Intelectual/fisiologia , Regulação da Expressão Gênica , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Proteínas Musculares/fisiologia , Animais , Região CA1 Hipocampal , Proteínas de Ligação ao Cálcio , Proteínas de Ligação a DNA , Síndrome de Down/genética , Síndrome de Down/metabolismo , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/metabolismo , Células HEK293 , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional/métodos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Morfogênese , Proteínas Musculares/metabolismo , Neurônios/metabolismo , Fosforilação , RNA Interferente Pequeno/metabolismo
8.
Proc Natl Acad Sci U S A ; 108(37): 15456-61, 2011 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-21876166

RESUMO

The proper distribution of mitochondria is particularly vital for neurons because of their polarized structure and high energy demand. Mitochondria in axons constantly move in response to physiological needs, but signals that regulate mitochondrial movement are not well understood. Aside from producing ATP, Ca(2+) buffering is another main function of mitochondria. Activities of many enzymes in mitochondria are also Ca(2+)-dependent, suggesting that intramitochondrial Ca(2+) concentration is important for mitochondrial functions. Here, we report that mitochondrial motility in axons is actively regulated by mitochondrial matrix Ca(2+). Ca(2+) entry through the mitochondrial Ca(2+) uniporter modulates mitochondrial transport, and mitochondrial Ca(2+) content correlates inversely with the speed of mitochondrial movement. Furthermore, the miro1 protein plays a role in Ca(2+) uptake into the mitochondria, which subsequently affects mitochondrial movement.


Assuntos
Axônios/metabolismo , Sinalização do Cálcio , Cálcio/metabolismo , Mitocôndrias/metabolismo , Animais , Canais de Cálcio/metabolismo , Motivos EF Hand , Humanos , Camundongos , Proteínas Mitocondriais/química , Proteínas Mitocondriais/metabolismo , Movimento , Mutação/genética
9.
Neurobiol Dis ; 56: 1-5, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23578490

RESUMO

Fragile X Syndrome (FXS) is a heritable form of mental retardation caused by a non-coding trinucleotide expansion of the FMR1 gene leading to loss of expression of this RNA binding protein. Mutations in this gene are strongly linked to enhanced Group I metabotropic glutamate receptor (mGluR) signaling. A recent report found that mGluR5-dependent endogenous cannabinoid signaling is enhanced in hippocampal slices from fmr1 knockout mice, suggesting a link between FXS and cannabinoid signaling. Alterations in cannabinoid signaling have an impact on learning and memory and may therefore be linked to some aspects of the FXS phenotype. We have used autaptic hippocampal neurons cultured from fmr1 knockout mice to further explore the interaction between endocannabinoid signaling and FMRP. These neurons express several robust forms of retrograde endocannabinoid signaling including depolarization induced suppression of excitation (DSE) and a metabotropic form (MSE) that results from Group I mGluR activation. We now report that young fmr1 neurons exhibit considerably enhanced DSE, likely via increased production of 2-AG, rather than enhanced mGluR-MSE. We find that depolarizations as brief as 50ms, which do not ordinarily produce DSE, routinely inhibited glutamate release. Furthermore, as neuronal cultures mature, CB1-receptor signaling strongly desensitizes. Our results suggest that loss of FMRP broadly affects the endocannabinoid signaling system, possibly through local 2-AG over production. Furthermore, the net effect of the loss of FMRP may actually be diminished cannabinoid signaling due to receptor desensitization as an adaptation to 2-AG overproduction.


Assuntos
Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Hipocampo/fisiopatologia , Neurônios/fisiologia , Receptor CB1 de Canabinoide/fisiologia , Sinapses/fisiologia , Adenosina/análogos & derivados , Adenosina/farmacologia , Animais , Baclofeno/farmacologia , Interpretação Estatística de Dados , Fenômenos Eletrofisiológicos , Potenciais Pós-Sinápticos Excitadores/genética , Potenciais Pós-Sinápticos Excitadores/fisiologia , Proteína do X Frágil da Deficiência Intelectual/fisiologia , Síndrome do Cromossomo X Frágil/fisiopatologia , Agonistas GABAérgicos/farmacologia , Metoxi-Hidroxifenilglicol/análogos & derivados , Metoxi-Hidroxifenilglicol/farmacologia , Camundongos , Camundongos Knockout , Receptor CB1 de Canabinoide/genética , Receptores de Glutamato Metabotrópico/biossíntese , Receptores de Glutamato Metabotrópico/genética
10.
PLoS Genet ; 6(12): e1001240, 2010 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-21170301

RESUMO

Fragile X Tremor Ataxia Syndrome (FXTAS) is a common inherited neurodegenerative disorder caused by expansion of a CGG trinucleotide repeat in the 5'UTR of the fragile X syndrome (FXS) gene, FMR1. The expanded CGG repeat is thought to induce toxicity as RNA, and in FXTAS patients mRNA levels for FMR1 are markedly increased. Despite the critical role of FMR1 mRNA in disease pathogenesis, the basis for the increase in FMR1 mRNA expression is unknown. Here we show that overexpressing any of three histone deacetylases (HDACs 3, 6, or 11) suppresses CGG repeat-induced neurodegeneration in a Drosophila model of FXTAS. This suppression results from selective transcriptional repression of the CGG repeat-containing transgene. These findings led us to evaluate the acetylation state of histones at the human FMR1 locus. In patient-derived lymphoblasts and fibroblasts, we determined by chromatin immunoprecipitation that there is increased acetylation of histones at the FMR1 locus in pre-mutation carriers compared to control or FXS derived cell lines. These epigenetic changes correlate with elevated FMR1 mRNA expression in pre-mutation cell lines. Consistent with this finding, histone acetyltransferase (HAT) inhibitors repress FMR1 mRNA expression to control levels in pre-mutation carrier cell lines and extend lifespan in CGG repeat-expressing Drosophila. These findings support a disease model whereby the CGG repeat expansion in FXTAS promotes chromatin remodeling in cis, which in turn increases expression of the toxic FMR1 mRNA. Moreover, these results provide proof of principle that HAT inhibitors or HDAC activators might be used to selectively repress transcription at the FMR1 locus.


Assuntos
Modelos Animais de Doenças , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/enzimologia , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/patologia , Inativação Gênica , Histona Desacetilases/metabolismo , Repetições de Trinucleotídeos , Acetilação , Adulto , Idoso de 80 Anos ou mais , Animais , Regulação para Baixo , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Inibidores Enzimáticos/farmacologia , Olho/enzimologia , Olho/inervação , Olho/patologia , Proteína do X Frágil da Deficiência Intelectual/genética , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Síndrome do Cromossomo X Frágil/tratamento farmacológico , Síndrome do Cromossomo X Frágil/enzimologia , Histona Acetiltransferases/antagonistas & inibidores , Desacetilase 6 de Histona , Histona Desacetilases/genética , Histonas/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade
11.
Mol Cells ; 46(6): 374-386, 2023 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-37077029

RESUMO

Thermal stress induces dynamic changes in nuclear proteins and relevant physiology as a part of the heat shock response (HSR). However, how the nuclear HSR is fine-tuned for cellular homeostasis remains elusive. Here, we show that mitochondrial activity plays an important role in nuclear proteostasis and genome stability through two distinct HSR pathways. Mitochondrial ribosomal protein (MRP) depletion enhanced the nucleolar granule formation of HSP70 and ubiquitin during HSR while facilitating the recovery of damaged nuclear proteins and impaired nucleocytoplasmic transport. Treatment of the mitochondrial proton gradient uncoupler masked MRP-depletion effects, implicating oxidative phosphorylation in these nuclear HSRs. On the other hand, MRP depletion and a reactive oxygen species (ROS) scavenger non-additively decreased mitochondrial ROS generation during HSR, thereby protecting the nuclear genome from DNA damage. These results suggest that suboptimal mitochondrial activity sustains nuclear homeostasis under cellular stress, providing plausible evidence for optimal endosymbiotic evolution via mitochondria-to-nuclear communication.


Assuntos
Resposta ao Choque Térmico , Proteostase , Humanos , Espécies Reativas de Oxigênio/metabolismo , Resposta ao Choque Térmico/genética , Proteínas de Choque Térmico HSP70/metabolismo , Mitocôndrias/metabolismo , Proteínas Nucleares/metabolismo , Instabilidade Genômica
12.
Proc Natl Acad Sci U S A ; 106(40): 17117-22, 2009 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-19805187

RESUMO

At the neuronal level of Down syndrome (DS) brains, there are evidences of altered shape, number, and density of synapses, as well as aberrant endocytosis associated with accumulation of enlarged endosomes, suggesting that proteins involved in synaptic vesicle recycling may play key roles in DS neurons. However, the exact mechanism underlying those anomalies is not well understood. We hypothesize that overexpression of three genes, dap160/itsn1, synj/synj1, and nla/dscr1, located on human chromosome 21 play important roles in DS neurons. Here, we systematically investigate the effects of multiple gene overexpression on synaptic morphology and endocytosis to identify possible dominant gene or genes. We found that overexpression of individual genes lead to abnormal synaptic morphology, but all three genes are necessary to cause impaired vesicle recycling and affect locomotor vigor. Furthermore, we report that dap160 overexpression alters the subcellular distribution of synaptojanin, and overexpression of nla regulates the phosphoinositol 5' phosphatase activity of synaptojanin. These findings imply that restoring the level of any one of these genes may reduce endocytic defects seen in DS.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Terminações Pré-Sinápticas/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Animais Geneticamente Modificados , Western Blotting , Proteínas de Ligação ao Cálcio , Cromossomos Humanos Par 21/genética , Proteínas de Ligação a DNA , Síndrome de Down/genética , Síndrome de Down/metabolismo , Síndrome de Down/fisiopatologia , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/fisiologia , Endocitose , Potenciais Evocados , Potenciais Pós-Sinápticos Excitadores , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Larva/genética , Larva/metabolismo , Larva/fisiologia , Modelos Biológicos , Atividade Motora/fisiologia , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Proteínas do Tecido Nervoso/genética , Neurônios/metabolismo , Neurônios/fisiologia , Monoéster Fosfórico Hidrolases/genética , Terminações Pré-Sinápticas/fisiologia , Regulação para Cima , Proteínas de Transporte Vesicular/genética
13.
Proc Natl Acad Sci U S A ; 105(25): 8673-8, 2008 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-18562277

RESUMO

Increased expression of the histone deacetylase sir2 has been reported to extend the life span of diverse organisms including yeast, Caenorhabditis elegans, and Drosophila melanogaster. A small molecule activator of Sir2, resveratrol, has also been suggested to extend the fitness and survival of these simple model organisms as well as mice fed high calorie diets. However, other studies in yeast have shown that Sir2 itself may prevent life extension, and high expression levels of Sir2 can be toxic to yeast and mouse cells. This conflicting evidence highlights the importance of understanding the mechanisms by which Sir2 expression or activation affects survival of organisms. To investigate the downstream signaling pathways affected by Sir2 in Drosophila, we generated transgenic flies expressing sir2. Here, we show that overexpression of sir2 in Drosophila promotes caspase-dependent but p53-independent apoptosis that is mediated by the JNK and FOXO signaling pathways. Furthermore, we find that a loss-of-function sir2 mutant partially prevents apoptosis induced by UV irradiation in the eye. Together, these results suggest that Sir2 normally participates in the regulation of cell survival and death in Drosophila.


Assuntos
Apoptose , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Histona Desacetilases/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Sistema de Sinalização das MAP Quinases , Sirtuínas/metabolismo , Animais , Morte Celular , Sobrevivência Celular , Drosophila/embriologia , Fatores de Transcrição Forkhead/metabolismo , Imuno-Histoquímica , Fenótipo , Raios Ultravioleta
14.
BMB Rep ; 53(1): 3-9, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31818361

RESUMO

The mitochondrial genome encodes 13 proteins that are components of the oxidative phosphorylation system (OXPHOS), suggesting that precise regulation of these genes is crucial for maintaining OXPHOS functions, including ATP production, calcium buffering, cell signaling, ROS production, and apoptosis. Furthermore, heteroplasmy or mis-regulation of gene expression in mitochondria frequently is associated with human mitochondrial diseases. Thus, various approaches have been developed to investigate the roles of genes encoded by the mitochondrial genome. In this review, we will discuss a wide range of techniques available for investigating the mitochondrial genome, mitochondrial transcription, and mitochondrial translation, which provide a useful guide to understanding mitochondrial gene expression. [BMB Reports 2020; 53(1): 3-9].


Assuntos
DNA Mitocondrial/genética , Proteínas Mitocondriais/metabolismo , RNA Mitocondrial/metabolismo , Animais , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , DNA Mitocondrial/metabolismo , Humanos , Hibridização in Situ Fluorescente , MicroRNAs/genética , MicroRNAs/metabolismo , Proteínas Mitocondriais/química , Biossíntese de Proteínas/efeitos dos fármacos , Biossíntese de Proteínas/genética , Nucleases dos Efetores Semelhantes a Ativadores de Transcrição/metabolismo , Transcrição Gênica
15.
Nat Neurosci ; 8(11): 1577-85, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16222229

RESUMO

Mitochondrial dysfunction has emerged as a common theme that underlies numerous neurological disorders, including Down syndrome. Down syndrome cultures and tissues show mitochondrial damage such as impaired mitochondrial enzyme activities, defective mitochondrial DNA repairs and accumulation of toxic free radicals, but the cause of mitochondrial dysfunction remains elusive. Here we demonstrate that the Drosophila melanogaster homolog of human Down syndrome critical region gene 1 (DSCR1), nebula (also known as sarah, sra), has a crucial role in the maintenance of mitochondrial function and integrity. We report that nebula protein is located in the mitochondria. An alteration in the abundance of nebula affects mitochondrial enzyme activities, mitochondrial DNA content, and the number and size of mitochondria. Furthermore, nebula interacts with the ADP/ATP translocator and influences its activity. These results identify nebula/DSCR1 as a regulator of mitochondrial function and integrity and further suggest that an increased level of DSCR1 may contribute to the mitochondrial dysfunction seen in Down syndrome.


Assuntos
Proteínas de Drosophila/química , Glicoproteínas de Membrana/fisiologia , Mitocôndrias/fisiologia , Trifosfato de Adenosina/metabolismo , Fatores Etários , Animais , Animais Geneticamente Modificados , Western Blotting/métodos , Encéfalo/metabolismo , Calcineurina/metabolismo , DNA Mitocondrial/metabolismo , Desmocolinas , Proteínas de Drosophila/genética , Drosophila melanogaster/química , Humanos , Imuno-Histoquímica/métodos , Imunoprecipitação/métodos , Larva , Glicoproteínas de Membrana/genética , Microscopia Eletrônica de Transmissão/métodos , Microscopia Imunoeletrônica/métodos , Mitocôndrias/ultraestrutura , Translocases Mitocondriais de ADP e ATP/metabolismo , Mutação , Neurópilo/metabolismo , Neurópilo/ultraestrutura , Células Fotorreceptoras de Invertebrados/ultraestrutura , Prostaglandina-Endoperóxido Sintases/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Frações Subcelulares/metabolismo , Succinato Desidrogenase/metabolismo
16.
Mol Cell Biol ; 39(4)2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30478144

RESUMO

Fragile X syndrome (FXS) caused by loss of fragile X mental retardation protein (FMRP), is the most common cause of inherited intellectual disability. Numerous studies show that FMRP is an RNA binding protein that regulates translation of its binding targets and plays key roles in neuronal functions. However, the regulatory mechanism for FMRP expression is incompletely understood. Conflicting results regarding internal ribosome entry site (IRES)-mediated fmr1 translation have been reported. Here, we unambiguously demonstrate that the fmr1 gene, which encodes FMRP, exploits both IRES-mediated translation and canonical cap-dependent translation. Furthermore, we find that heterogeneous nuclear ribonucleoprotein Q (hnRNP Q) acts as an IRES-transacting factor (ITAF) for IRES-mediated fmr1 translation in neurons. We also show that semaphorin 3A (Sema3A)-induced axonal growth cone collapse is due to upregulation of hnRNP Q and subsequent IRES-mediated expression of FMRP. These data elucidate the regulatory mechanism of FMRP expression and its role in axonal growth cone collapse.


Assuntos
Proteína do X Frágil da Deficiência Intelectual/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas/metabolismo , Neurônios/metabolismo , Animais , Linhagem Celular , Proteína do X Frágil da Deficiência Intelectual/genética , Síndrome do Cromossomo X Frágil/genética , Síndrome do Cromossomo X Frágil/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas/genética , Sítios Internos de Entrada Ribossomal , Camundongos , Camundongos Endogâmicos C57BL , Biossíntese de Proteínas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
17.
Curr Biol ; 15(17): 1578-82, 2005 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-16139214

RESUMO

The loss of dopaminergic neurons in the substantia nigra is the pathological hallmark of Parkinson's disease (PD). While the etiology of sporadic PD remains elusive, an inherited form of early-onset familial PD is linked to mutations of DJ-1. To understand the biological function of DJ-1 and its relevance to the pathogenesis of PD, we investigated the function of DJ-1 using Drosophila. Drosophila possesses two homologs of human DJ-1: DJ-1alpha and DJ-1beta. We found that DJ-1alpha is expressed predominantly in the testis, while DJ-1beta is ubiquitously present in most tissues, resembling the expression pattern of human DJ-1. Loss-of-function DJ-1beta mutants demonstrated an extended survival of dopaminergic neurons and resistance to paraquat stress, but showed acute sensitivity to hydrogen peroxide treatment. We showed a compensatory upregulation of DJ-1alpha expression in the brain of the DJ-1beta mutant and demonstrated that overexpression of DJ-1alpha in dopaminergic neurons is sufficient to confer protection against paraquat insult. These results suggest that Drosophila homologs of DJ-1 play critical roles in the survival of dopaminergic neurons and response to oxidative stress.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Estresse Oxidativo/genética , Sequência de Aminoácidos , Animais , Western Blotting , Encéfalo/metabolismo , Dopamina/metabolismo , Drosophila/genética , Proteínas de Drosophila/genética , Perfilação da Expressão Gênica , Peróxido de Hidrogênio/toxicidade , Imuno-Histoquímica , Dados de Sequência Molecular , Mutação/genética , Proteínas do Tecido Nervoso/genética , Neurônios/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Paraquat/toxicidade , Proteína Desglicase DJ-1 , Alinhamento de Sequência
18.
FEBS Lett ; 582(5): 715-9, 2008 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-18258192

RESUMO

In Friedreich's ataxia, reduction of the mitochondria protein frataxin results in the accumulation of iron and reactive oxygen species, which leads to oxidative damage, neurodegeneration and a diminished lifespan. Recent studies propose that frataxin might play a role in the antioxidative process. Here we show that overexpression of Drosophila frataxin in the mitochondria of female transgenic animals increases antioxidant capability, resistance to oxidative stress insults, and longevity. This suggests that Drosophila frataxin may function to protect the mitochondria from oxidative stresses and the ensuing cellular damage.


Assuntos
Drosophila melanogaster/metabolismo , Expressão Gênica , Proteínas de Ligação ao Ferro/genética , Longevidade , Mitocôndrias/metabolismo , Estresse Oxidativo , Animais , Animais Geneticamente Modificados , Antioxidantes , Drosophila melanogaster/genética , Regulação da Expressão Gênica , Proteínas de Ligação ao Ferro/metabolismo , RNA Mensageiro , Frataxina
19.
Mol Cells ; 41(12): 1000-1007, 2018 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-30590907

RESUMO

Mitochondria and endoplasmic reticulum (ER) are essential organelles in eukaryotic cells, which play key roles in various biological pathways. Mitochondria are responsible for ATP production, maintenance of Ca2+ homeostasis and regulation of apoptosis, while ER is involved in protein folding, lipid metabolism as well as Ca2+ homeostasis. These organelles have their own functions, but they also communicate via mitochondrial-associated ER membrane (MAM) to provide another level of regulations in energy production, lipid process, Ca2+ buffering, and apoptosis. Hence, defects in MAM alter cell survival and death. Here, we review components forming the molecular junctions of MAM and how MAM regulates cellular functions. Furthermore, we discuss the effects of impaired ER-mitochondrial communication in various neurodegenerative diseases.


Assuntos
Retículo Endoplasmático/metabolismo , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Doenças Neurodegenerativas/metabolismo , Humanos , Doenças Neurodegenerativas/patologia
20.
Mol Cell Biol ; 23(20): 7210-21, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14517291

RESUMO

The tyrosine phosphorylation sites of the Disabled 1 (Dab1) docking protein are essential for the transmission of the Reelin signal, which regulates neuronal placement. Here we identify Nck beta as a phosphorylation-dependent, Dab1-interacting protein. The SH2 domain of Nck beta but not Nck alpha binds Dab1 phosphorylated on the Reelin-regulated site, Y220, or on Y232. Nck beta is coexpressed with Dab1 in the developing brain and in cultured neurons, where Reelin stimulation leads to the redistribution of Nck beta from the cell soma into neuronal processes. We found that tyrosine-phosphorylated Dab1 in synergy with Nck beta disrupts the actin cytoskeleton in transfected cells. In Drosophila melanogaster, exogenous expression of mouse Dab1 causes tyrosine phosphorylation site-dependent morphological changes in the compound eye. This phenotype is enhanced by overexpression of the Drosophila Nck protein Dock, suggesting a conserved interaction between the Disabled and Nck family members. We suggest a model in which Dab1 phosphorylation leads to the recruitment of Nck beta to the membrane, where it acts to remodel the actin cytoskeleton.


Assuntos
Proteínas de Transporte/metabolismo , Moléculas de Adesão Celular Neuronais/metabolismo , Proteínas de Drosophila , Proteínas da Matriz Extracelular/metabolismo , Proteínas do Tecido Nervoso/fisiologia , Neurônios/metabolismo , Tirosina/metabolismo , Actinas/metabolismo , Animais , Linhagem Celular , Citoesqueleto/metabolismo , Drosophila melanogaster/metabolismo , Humanos , Imuno-Histoquímica , Camundongos , Microscopia Eletrônica de Varredura , Fosforilação , Plasmídeos/metabolismo , Testes de Precipitina , Ligação Proteica , Estrutura Terciária de Proteína , Ratos , Proteína Reelina , Serina Endopeptidases , Fatores de Tempo , Técnicas do Sistema de Duplo-Híbrido , Domínios de Homologia de src
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