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1.
Mol Cell ; 67(4): 608-621.e6, 2017 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-28757210

RESUMO

Transcription is a source of genetic instability that can notably result from the formation of genotoxic DNA:RNA hybrids, or R-loops, between the nascent mRNA and its template. Here we report an unexpected function for introns in counteracting R-loop accumulation in eukaryotic genomes. Deletion of endogenous introns increases R-loop formation, while insertion of an intron into an intronless gene suppresses R-loop accumulation and its deleterious impact on transcription and recombination in yeast. Recruitment of the spliceosome onto the mRNA, but not splicing per se, is shown to be critical to attenuate R-loop formation and transcription-associated genetic instability. Genome-wide analyses in a number of distant species differing in their intron content, including human, further revealed that intron-containing genes and the intron-richest genomes are best protected against R-loop accumulation and subsequent genetic instability. Our results thereby provide a possible rationale for the conservation of introns throughout the eukaryotic lineage.


Assuntos
DNA Fúngico/genética , Instabilidade Genômica , Íntrons , Ácidos Nucleicos Heteroduplexes/genética , RNA Fúngico/genética , Transcrição Gênica , Candida glabrata/genética , Candida glabrata/metabolismo , Linhagem Celular , Biologia Computacional , Cryptococcus neoformans/genética , Cryptococcus neoformans/metabolismo , Dano ao DNA , DNA Fúngico/química , DNA Fúngico/metabolismo , Bases de Dados Genéticas , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Genótipo , Humanos , Conformação de Ácido Nucleico , Ácidos Nucleicos Heteroduplexes/química , Ácidos Nucleicos Heteroduplexes/metabolismo , Fenótipo , Splicing de RNA , RNA Fúngico/química , RNA Fúngico/metabolismo , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Spliceossomos/genética , Spliceossomos/metabolismo , Relação Estrutura-Atividade
2.
EMBO J ; 39(17): e104337, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32677087

RESUMO

Integration of transposable elements into the genome is mutagenic. Mechanisms targeting integrations into relatively safe locations, hence minimizing deleterious consequences for cell fitness, have emerged during evolution. In budding yeast, integration of the Ty1 LTR retrotransposon upstream of RNA polymerase III (Pol III)-transcribed genes requires interaction between Ty1 integrase (IN1) and AC40, a subunit common to Pol I and Pol III. Here, we identify the Ty1 targeting domain of IN1 that ensures (i) IN1 binding to Pol I and Pol III through AC40, (ii) IN1 genome-wide recruitment to Pol I- and Pol III-transcribed genes, and (iii) Ty1 integration only at Pol III-transcribed genes, while IN1 recruitment by AC40 is insufficient to target Ty1 integration into Pol I-transcribed genes. Swapping the targeting domains between Ty5 and Ty1 integrases causes Ty5 integration at Pol III-transcribed genes, indicating that the targeting domain of IN1 alone confers Ty1 integration site specificity.


Assuntos
Integrases/metabolismo , RNA Polimerase III/metabolismo , RNA Polimerase I/metabolismo , RNA de Transferência/genética , Retroelementos , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Integrases/genética , RNA Polimerase I/genética , RNA Polimerase III/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética
3.
PLoS Genet ; 17(11): e1009889, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34723966

RESUMO

Beyond their canonical function in nucleocytoplasmic exchanges, nuclear pore complexes (NPCs) regulate the expression of protein-coding genes. Here, we have implemented transcriptomic and molecular methods to specifically address the impact of the NPC on retroelements, which are present in multiple copies in genomes. We report a novel function for the Nup84 complex, a core NPC building block, in specifically restricting the transcription of LTR-retrotransposons in yeast. Nup84 complex-dependent repression impacts both Copia and Gypsy Ty LTR-retrotransposons, all over the S. cerevisiae genome. Mechanistically, the Nup84 complex restricts the transcription of Ty1, the most active yeast retrotransposon, through the tethering of the SUMO-deconjugating enzyme Ulp1 to NPCs. Strikingly, the modest accumulation of Ty1 RNAs caused by Nup84 complex loss-of-function is sufficient to trigger an important increase of Ty1 cDNA levels, resulting in massive Ty1 retrotransposition. Altogether, our study expands our understanding of the complex interactions between retrotransposons and the NPC, and highlights the importance for the cells to keep retrotransposons under tight transcriptional control.


Assuntos
Poro Nuclear/metabolismo , Retroelementos , Transcrição Gênica , Genes Fúngicos , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , RNA Fúngico/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
4.
Curr Genet ; 67(3): 347-357, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33590295

RESUMO

Transposable elements are ubiquitous in genomes. Their successful expansion depends in part on their sites of integration in their host genome. In Saccharomyces cerevisiae, evolution has selected various strategies to target the five Ty LTR-retrotransposon families into gene-poor regions in a genome, where coding sequences occupy 70% of the DNA. The integration of Ty1/Ty2/Ty4 and Ty3 occurs upstream and at the transcription start site of the genes transcribed by RNA polymerase III, respectively. Ty5 has completely different integration site preferences, targeting heterochromatin regions. Here, we review the history that led to the identification of the cellular tethering factors that play a major role in anchoring Ty retrotransposons to their preferred sites. We also question the involvement of additional factors in the fine-tuning of the integration site selection, with several studies converging towards an importance of the structure and organization of the chromatin.


Assuntos
DNA Fúngico/genética , Evolução Molecular , Genoma Fúngico/genética , Retroelementos/genética , Humanos , Saccharomyces cerevisiae/genética
5.
Cell Mol Life Sci ; 73(1): 217-36, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26202697

RESUMO

Membrane-type 5-matrix metalloproteinase (MT5-MMP) is a proteinase mainly expressed in the nervous system with emerging roles in brain pathophysiology. The implication of MT5-MMP in Alzheimer's disease (AD), notably its interplay with the amyloidogenic process, remains elusive. Accordingly, we crossed the genetically engineered 5xFAD mouse model of AD with MT5-MMP-deficient mice and examined the impact of MT5-MMP deficiency in bigenic 5xFAD/MT5-MMP(-/-) mice. At early stages (4 months) of the pathology, the levels of amyloid beta peptide (Aß) and its amyloid precursor protein (APP) C-terminal fragment C99 were largely reduced in the cortex and hippocampus of 5xFAD/MT5-MMP(-/-), compared to 5xFAD mice. Reduced amyloidosis in bigenic mice was concomitant with decreased glial reactivity and interleukin-1ß (IL-1ß) levels, and the preservation of long-term potentiation (LTP) and spatial learning, without changes in the activity of α-, ß- and γ-secretases. The positive impact of MT5-MMP deficiency was still noticeable at 16 months of age, as illustrated by reduced amyloid burden and gliosis, and a better preservation of the cortical neuronal network and synaptophysin levels in bigenic mice. MT5-MMP expressed in HEKswe cells colocalized and co-immunoprecipitated with APP and significantly increased the levels of Aß and C99. MT5-MMP also promoted the release of a soluble APP fragment of 95 kDa (sAPP95) in HEKswe cells. sAPP95 levels were significantly reduced in brain homogenates of 5xFAD/MT5-MMP(-/-) mice, supporting altogether the idea that MT5-MMP influences APP processing. MT5-MMP emerges as a new pro-amyloidogenic regulator of APP metabolism, whose deficiency alleviates amyloid pathology, neuroinflammation and cognitive decline.


Assuntos
Doença de Alzheimer/enzimologia , Doença de Alzheimer/fisiopatologia , Hipocampo/enzimologia , Hipocampo/fisiopatologia , Metaloproteinases da Matriz Associadas à Membrana/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Secretases da Proteína Precursora do Amiloide/análise , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/análise , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/análise , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Cognição , Feminino , Deleção de Genes , Células HEK293 , Hipocampo/metabolismo , Hipocampo/patologia , Humanos , Potenciação de Longa Duração , Masculino , Metaloproteinases da Matriz Associadas à Membrana/análise , Metaloproteinases da Matriz Associadas à Membrana/genética , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Aprendizagem Espacial
6.
Nucleic Acids Res ; 43(8): 4249-61, 2015 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-25845599

RESUMO

Several nuclear pore-associated factors, including the SUMO-protease Ulp1, have been proposed to prevent the export of intron-containing messenger ribonucleoparticles (mRNPs) in yeast. However, the molecular mechanisms of this nuclear pore-dependent mRNA quality control, including the sumoylated targets of Ulp1, have remained unidentified. Here, we demonstrate that the apparent 'pre-mRNA leakage' phenotype arising upon ULP1 inactivation is shared by sumoylation mutants of the THO complex, an early mRNP biogenesis factor. Importantly, we establish that alteration of THO complex activity differentially impairs the expression of intronless and intron-containing reporter genes, rather than triggering bona fide 'pre-mRNA leakage'. Indeed, we show that the presence of introns within THO target genes attenuates the effect of THO inactivation on their transcription. Epistasis analyses further clarify that different nuclear pore components influence intron-containing gene expression at distinct stages. Ulp1, whose maintenance at nuclear pores depends on the Nup84 complex, impacts on THO-dependent gene expression, whereas the nuclear basket-associated Mlp1/Pml39 proteins prevent pre-mRNA export at a later stage, contributing to mRNA quality control. Our study thus highlights the multiplicity of mechanisms by which nuclear pores contribute to gene expression, and further provides the first evidence that intronic sequences can alleviate early mRNP biogenesis defects.


Assuntos
Cisteína Endopeptidases/metabolismo , Regulação Fúngica da Expressão Gênica , Íntrons , Complexo de Proteínas Formadoras de Poros Nucleares/fisiologia , RNA Mensageiro/metabolismo , Proteínas de Ligação a DNA/genética , Mutação , Poro Nuclear/enzimologia , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Precursores de RNA/metabolismo , Ribonucleoproteínas/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Sumoilação , Transcrição Gênica
7.
J Neuroinflammation ; 13(1): 290, 2016 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-27832801

RESUMO

BACKGROUND: The heterogeneity of endothelial cell types underlies their remarkable ability to sub-specialize and provide specific requirements for a given vascular bed. Here, we compared rat microvascular endothelial cells (MECs) derived from the brain and spinal cord in both basal and inflammatory conditions. METHODS: We used whole rat genome microarrays to compare, at different time points, basal and TNF-α-induced gene expression of rat MECs from in vitro models of the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB). Validation at both messenger RNA (mRNA) and protein levels was performed on freshly extracted microvessels (MVs) from the brain and spinal cord (BMVs and SCMVs, respectively), as these were considered the closest in vivo tissues to cultured MECs. RESULTS: Most of the genes encoding adhesion/tight junction molecules and known endothelial markers were similarly expressed in brain and spinal cord MECs (BMECs and SCMECs, respectively). However, one striking finding was the higher expression of several Hox genes, which encode transcription factors involved in positional identity. The differential expression of Hoxa9 and Hoxb7 at the mRNA levels as well as protein levels was confirmed in BMVs and SCMVs. Although the TNF-α response was in general higher in BMECs than in SCMECs at 12 h, the opposite was observed at 48 h. Furthermore, we found that expression of Tnfrsf1a and Tnfrsf1b encoding the TNF receptor super-family member 1a/TNFR1 and 1b/TNFR2, respectively, were constitutively higher in BMVs compared to SCMVs. However, only Tnfrsf1b was induced in SCMECs in response to TNF-α at 24 and 48 h. CONCLUSIONS: Our results support a role for HOX members in defining the positional identities of MECs in vivo. Our data also suggest that the delayed transcriptional activation upon TNF-α treatment in SCMECs results from the requirement of the TNF-induced expression of Tnfrsf1b. In contrast, its high basal expression in BMECs might be sufficient to confer an immediate and efficient TNF-α response.


Assuntos
Encéfalo/citologia , Células Endoteliais/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Proteínas de Homeodomínio/metabolismo , Medula Espinal/citologia , Fator de Necrose Tumoral alfa/farmacologia , Animais , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Citocinas/metabolismo , Perfilação da Expressão Gênica , Proteínas de Homeodomínio/genética , Análise em Microsséries , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Receptores Tipo II do Fator de Necrose Tumoral/genética , Receptores Tipo II do Fator de Necrose Tumoral/metabolismo , Fatores de Tempo
8.
J Virol ; 88(18): 10655-61, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24991007

RESUMO

UNLABELLED: Whether NF-κB promoter transactivation by the human T-cell leukemia virus type 1 (HTLV-1) Tax protein requires Tax SUMOylation is still a matter of debate. In this study, we revisited the role of Tax SUMOylation using a strategy based on the targeting of Ubc9, the unique E2 SUMO-conjugating enzyme. We show that either a catalytically inactive form of Ubc9 (Ubc9-C93S) or Ubc9 small interfering RNA (siRNA) dramatically reduces Tax conjugation to endogenous SUMO-1 or SUMO-2/3, demonstrating that as expected, Tax SUMOylation is under the control of the catalytic activity of Ubc9. We further report that a non-SUMOylated Tax protein produced in 293T cells is still able to activate either a transfected or an integrated NF-κB reporter promoter and to induce expression of an NF-κB-regulated endogenous gene. Importantly, blocking Ubc9 activity in T cells also results in the production of a non-SUMOylated Tax that is still fully functional for the activation of a NF-κB promoter. These results provide the definitive evidence that Tax SUMOylation is not required for NF-κB-driven gene induction. IMPORTANCE: Human T-cell leukemia virus type 1 is able to transform CD4(+) T lymphocytes. The viral oncoprotein Tax plays a key role in this process by promoting cell proliferation and survival, mainly through permanent activation of the NF-κB pathway. Elucidating the molecular mechanisms involved in NF-κB pathway activation by Tax is therefore a key issue to understand HTLV-1-mediated transformation. Tax SUMOylation was initially proposed to be critical for Tax-induced NF-κB promoter activation, which was challenged by our later observation that a low-level-SUMOylated Tax mutant was still functional for activation of NF-κB promoters. To clarify the role of Tax SUMOylation, we set up a new approach based on the inhibition of the SUMOylation machinery in Tax-expressing cells. We show that blocking the SUMO-conjugating enzyme Ubc9 abolishes Tax SUMOylation and that a non-SUMOylated Tax still activates NF-κB promoters in either adherent cells or T cells.


Assuntos
Produtos do Gene tax/metabolismo , Infecções por HTLV-I/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , NF-kappa B/genética , Ativação Transcricional , Produtos do Gene tax/genética , Infecções por HTLV-I/enzimologia , Infecções por HTLV-I/genética , Infecções por HTLV-I/virologia , Vírus Linfotrópico T Tipo 1 Humano/genética , Humanos , NF-kappa B/metabolismo , Regiões Promotoras Genéticas , Sumoilação , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo
9.
J Virol ; 87(2): 1123-36, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23135727

RESUMO

Permanent activation of the NF-κB pathway by the human T cell leukemia virus type 1 (HTLV-1) Tax (Tax1) viral transactivator is a key event in the process of HTLV-1-induced T lymphocyte immortalization and leukemogenesis. Although encoding a Tax transactivator (Tax2) that activates the canonical NF-κB pathway, HTLV-2 does not cause leukemia. These distinct pathological outcomes might be related, at least in part, to distinct NF-κB activation mechanisms. Tax1 has been shown to be both ubiquitinated and SUMOylated, and these two modifications were originally proposed to be required for Tax1-mediated NF-κB activation. Tax1 ubiquitination allows recruitment of the IKK-γ/NEMO regulatory subunit of the IKK complex together with Tax1 into centrosome/Golgi-associated cytoplasmic structures, followed by activation of the IKK complex and RelA/p65 nuclear translocation. Herein, we compared the ubiquitination, SUMOylation, and acetylation patterns of Tax2 and Tax1. We show that, in contrast to Tax1, Tax2 conjugation to endogenous ubiquitin and SUMO is barely detectable while both proteins are acetylated. Importantly, Tax2 is neither polyubiquitinated on lysine residues nor ubiquitinated on its N-terminal residue. Consistent with these observations, Tax2 conjugation to ubiquitin and Tax2-mediated NF-κB activation is not affected by overexpression of the E2 conjugating enzyme Ubc13. We further demonstrate that a nonubiquitinable, non-SUMOylable, and nonacetylable Tax2 mutant retains a significant ability to activate transcription from a NF-κB-dependent promoter after partial activation of the IKK complex and induction of RelA/p65 nuclear translocation. Finally, we also show that Tax2 does not interact with TRAF6, a protein that was shown to positively regulate Tax1-mediated activation of the NF-κB pathway.


Assuntos
Produtos do Gene tax/metabolismo , Vírus Linfotrópico T Tipo 2 Humano/patogenicidade , NF-kappa B/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Sumoilação , Ubiquitina/metabolismo , Acetilação , Células HeLa , Humanos , Células Jurkat , Processamento de Proteína Pós-Traducional
10.
Retrovirology ; 9: 77, 2012 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-23009398

RESUMO

BACKGROUND: The Tax protein encoded by Human T-lymphotropic virus type 1 (HTLV-1) is a powerful activator of the NF-κB pathway, a property critical for HTLV-1-induced immortalization of CD4⁺ T lymphocytes. Tax permanently stimulates this pathway at a cytoplasmic level by activating the IκB kinase (IKK) complex and at a nuclear level by enhancing the binding of the NF-κB factor RelA to its cognate promoters and by forming nuclear bodies, believed to represent transcriptionally active structures. In previous studies, we reported that Tax ubiquitination and SUMOylation play a critical role in Tax localization and NF-κB activation. Indeed, analysis of lysine Tax mutants fused or not to ubiquitin or SUMO led us to propose a two-step model in which Tax ubiquitination first intervenes to activate IKK while Tax SUMOylation is subsequently required for promoter activation within Tax nuclear bodies. However, recent studies showing that ubiquitin or SUMO can modulate Tax activities in either the nucleus or the cytoplasm and that SUMOylated Tax can serve as substrate for ubiquitination suggested that Tax ubiquitination and SUMOylation may mediate redundant rather than successive functions. RESULTS: In this study, we analyzed the properties of a new Tax mutant that is properly ubiquitinated, but defective for both nuclear body formation and SUMOylation. We report that reducing Tax SUMOylation and nuclear body formation do not alter the ability of Tax to activate IKK, induce RelA nuclear translocation, and trigger gene expression from a NF-κB promoter. Importantly, potent NF-κB promoter activation by Tax despite low SUMOylation and nuclear body formation is also observed in T cells, including CD4⁺ primary T lymphocytes. Moreover, we show that Tax nuclear bodies are hardly observed in HTLV-1-infected T cells. Finally, we provide direct evidence that the degree of NF-κB activation by Tax correlates with the level of Tax ubiquitination, but not SUMOylation. CONCLUSIONS: These data reveal that the formation of Tax nuclear bodies, previously associated to transcriptional activities in Tax-transfected cells, is dispensable for NF-κB promoter activation, notably in CD4⁺ T cells. They also provide the first evidence that Tax SUMOylation is not a key determinant for Tax-induced NF-κB activation.


Assuntos
Produtos do Gene tax/metabolismo , Espaço Intranuclear/metabolismo , NF-kappa B/metabolismo , Regiões Promotoras Genéticas , Processamento de Proteína Pós-Traducional , Ativação Transcricional , Substituição de Aminoácidos , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/virologia , Linhagem Celular , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Produtos do Gene tax/genética , Genes Reporter , Interações Hospedeiro-Patógeno , Vírus Linfotrópico T Tipo 1 Humano/metabolismo , Vírus Linfotrópico T Tipo 1 Humano/fisiologia , Humanos , Quinase I-kappa B/metabolismo , Luciferases de Renilla/biossíntese , Luciferases de Renilla/genética , Microscopia Confocal , NF-kappa B/fisiologia , Ligação Proteica , Transporte Proteico , Proteínas Recombinantes de Fusão/metabolismo , Proteína SUMO-1/metabolismo , Transdução de Sinais , Sumoilação , Transcrição Gênica , Ubiquitinação
11.
Mob DNA ; 13(1): 26, 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36401307

RESUMO

BACKGROUND: Transposable elements are ubiquitous and play a fundamental role in shaping genomes during evolution. Since excessive transposition can be mutagenic, mechanisms exist in the cells to keep these mobile elements under control. Although many cellular factors regulating the mobility of the retrovirus-like transposon Ty1 in Saccharomyces cerevisiae have been identified in genetic screens, only very few of them interact physically with Ty1 integrase (IN). RESULTS: Here, we perform a proteomic screen to establish Ty1 IN interactome. Among the 265 potential interacting partners, we focus our study on the conserved CK2 kinase. We confirm the interaction between IN and CK2, demonstrate that IN is a substrate of CK2 in vitro and identify the modified residues. We find that Ty1 IN is phosphorylated in vivo and that these modifications are dependent in part on CK2. No significant change in Ty1 retromobility could be observed when we introduce phospho-ablative mutations that prevent IN phosphorylation by CK2 in vitro. However, the absence of CK2 holoenzyme results in a strong stimulation of Ty1 retrotransposition, characterized by an increase in Ty1 mRNA and protein levels and a high accumulation of cDNA. CONCLUSION: Our study shows that Ty1 IN is phosphorylated, as observed for retroviral INs and highlights an important role of CK2 in the regulation of Ty1 retrotransposition. In addition, the proteomic approach enabled the identification of many new Ty1 IN interacting partners, whose potential role in the control of Ty1 mobility will be interesting to study.

12.
Brief Funct Genomics ; 19(2): 101-110, 2020 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-32048721

RESUMO

The spatial organization of the genome contributes to essential functions such as transcription and chromosome integrity maintenance. The principles governing nuclear compartmentalization have been the focus of considerable research over the last decade. In these studies, the genome-nuclear structure interactions emerged as a main driver of this particular 3D genome organization. In this review, we describe the interactions between the genome and four major landmarks of the nucleus: the nuclear lamina, the nuclear pores, the pericentromeric heterochromatin and the nucleolus. We present the recent studies that identify sequences bound to these different locations and address the tethering mechanisms. We give an overview of the relevance of this organization in development and disease. Finally, we discuss the dynamic aspects and self-organizing properties that allow this complex architecture to be inherited.


Assuntos
Núcleo Celular/metabolismo , Lâmina Nuclear/metabolismo , Poro Nuclear/metabolismo , Animais , Humanos
13.
J Neurotrauma ; 35(15): 1765-1780, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29357739

RESUMO

The transplantation of olfactory ecto-mesenchymal stem cells (OEMSCs) could be a helpful therapeutic strategy for spinal cord repair. Using an acute rat model of high cervical contusion that provokes a persistent hemidiaphragmatic and foreleg paralysis, we evaluated the therapeutic effect of a delayed syngeneic transplantation (two days post-contusion) of OEMSCs within the injured spinal cord. Respiratory function was assessed using diaphragmatic electromyography and neuroelectrophysiological recordings of phrenic nerves (innervating the diaphragm). Locomotor function was evaluated using the ladder-walking locomotor test. Cellular reorganization in the injured area was also studied using immunohistochemical and microscopic techniques. We report a substantial improvement in breathing movements, in activities of the ipsilateral phrenic nerve and ipsilateral diaphragm, and also in locomotor abilities four months post-transplantation with nasal OEMSCs. Moreover, in the grafted spinal cord, axonal disorganization and inflammation were reduced. Some grafted stem cells adopted a neuronal phenotype, and axonal sparing was observed in the injury site. The therapeutic effect on the supraspinal command is presumably because of both neuronal replacements and beneficial paracrine effects on the injury area. Our study provides evidence that nasal OEMSCs could be a first step in clinical application, particularly in patients with reduced breathing/locomotor movements.


Assuntos
Transplante de Células-Tronco Mesenquimais/métodos , Recuperação de Função Fisiológica/fisiologia , Respiração , Traumatismos da Medula Espinal/fisiopatologia , Regeneração da Medula Espinal/fisiologia , Animais , Diafragma/inervação , Mucosa Nasal/citologia , Ratos , Ratos Endogâmicos F344
14.
Nat Commun ; 9(1): 1341, 2018 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-29632298

RESUMO

Transposable elements are in a constant arms race with the silencing mechanisms of their host genomes. One silencing mechanism commonly used by many eukaryotes is dependent on cytosine methylation, a covalent modification of DNA deposited by C5 cytosine methyltransferases (DNMTs). Here, we report how two distantly related eukaryotic lineages, dinoflagellates and charophytes, have independently incorporated DNMTs into the coding regions of distinct retrotransposon classes. Concomitantly, we show that dinoflagellates of the genus Symbiodinium have evolved cytosine methylation patterns unlike any other eukaryote, with most of the genome methylated at CG dinucleotides. Finally, we demonstrate the ability of retrotransposon DNMTs to methylate CGs de novo, suggesting that retrotransposons could self-methylate retrotranscribed DNA. Together, this is an example of how retrotransposons incorporate host-derived genes involved in DNA methylation. In some cases, this event could have implications for the composition and regulation of the host epigenomic environment.


Assuntos
Carofíceas/enzimologia , Carofíceas/genética , DNA (Citosina-5-)-Metiltransferases/genética , DNA (Citosina-5-)-Metiltransferases/metabolismo , Dinoflagellida/enzimologia , Dinoflagellida/genética , Retroelementos , Metilação de DNA/genética , Epigênese Genética , Evolução Molecular , Inativação Gênica , Filogenia
15.
Nat Commun ; 9(1): 1811, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29717194

RESUMO

The original version of this Article contained an error in the spelling of the author Hongfei Li, which was incorrectly given as Fei Hong. This has now been corrected in both the PDF and HTML versions of the Article.

17.
Cell Discov ; 3: 17040, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29071121

RESUMO

The Set1 family of histone H3 lysine 4 (H3K4) methyltransferases is highly conserved from yeast to human. Here we show that the Set1 complex (Set1C) directly binds RNA in vitro through the regions that comprise the double RNA recognition motifs (dRRM) and N-SET domain within Set1 and its subunit Spp1. To investigate the functional relevance of RNA binding, we performed UV RNA crosslinking (CRAC) for Set1 and RNA polymerase II in parallel with ChIP-seq experiments. Set1 binds nascent transcripts through its dRRM. RNA binding is important to define the appropriate topology of Set1C distribution along transcription units and correlates with the efficient deposition of the H3K4me3 mark. In addition, we uncovered that Set1 binds to different classes of RNAs to levels that largely exceed the levels of binding to the general population of transcripts, suggesting the Set1 persists on these RNAs after transcription. This class includes RNAs derived from SET1, Ty1 retrotransposons, specific transcription factors genes and snRNAs (small nuclear RNAs). We propose that Set1 modulates adaptive responses, as exemplified by the post-transcriptional inhibition of Ty1 retrotransposition.

18.
Front Mol Neurosci ; 9: 163, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28119565

RESUMO

We previously reported that deficiency of membrane-type five matrix metalloproteinase (MT5-MMP) prevents amyloid pathology in the cortex and hippocampus of 5xFAD mice, and ameliorates the functional outcome. We have now investigated whether the integrity of another important area affected in Alzheimer's disease (AD), the frontal cortex, was also preserved upon MT5-MMP deficiency in 4-month old mice at prodromal stages of the pathology. We used the olfactory H-maze (OHM) to show that learning impairment associated with dysfunctions of the frontal cortex in 5xFAD was prevented in bigenic 5xFAD/MT5-MMP-/- mice. The latter exhibited concomitant drastic reductions of amyloid beta peptide (Aß) assemblies (soluble, oligomeric and fibrillary) and its immediate precursor, C99. Simultaneously, astrocyte reactivity and tumor necrosis factor alpha (TNF-α) levels were also lowered. Moreover, MT5-MMP deficiency induced a decrease in N-terminal soluble fragments of amyloid precursor protein (APP), including soluble APPα (sAPPα), sAPPß and the MT5-MMP-linked fragment of 95 kDa, sAPP95. However, the lack of MT5-MMP did not affect the activity of ß- and γ-secretases. In cultured HEKswe cells, transiently expressed MT5-MMP localized to early endosomes and increased the content of APP and Aß40 in these organelles, as well as Aß levels in cell supernatants. This is the first evidence that the pro-amyloidogenic features of MT5-MMP lie, at least in part, on the ability of the proteinase to promote trafficking into one of the amyloidogenic subcellular loci. Together, our data further support the pathogenic role of MT5-MMP in AD and that its inhibition improves the functional and pathological outcomes, in this case in the frontal cortex. These data also support the idea that MT5-MMP could become a novel therapeutic target in AD.

19.
Nucleus ; 6(6): 455-61, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26709543

RESUMO

Nuclear pore complexes (NPCs) have been shown to regulate distinct steps of the gene expression process, from transcription to mRNA export. In particular, mRNAs expressed from intron-containing genes are surveyed by a specific NPC-dependent quality control pathway ensuring that unspliced mRNAs are retained within the nucleus. In this Extra View, we summarize the different approaches that have been developed to evaluate the contribution of various NPC components to the expression of intron-containing genes. We further present the mechanistic models that could account for pre-mRNA retention at the nuclear side of NPCs. Finally, we discuss the possibility that other stages of intron-containing gene expression could be regulated by nuclear pores, in particular through the regulation of mRNA biogenesis factors by the NPC-associated SUMO protease Ulp1.


Assuntos
Núcleo Celular/metabolismo , Poro Nuclear/metabolismo , Cisteína Endopeptidases/metabolismo , Íntrons , Modelos Moleculares , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , RNA Mensageiro/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Sumoilação , Transcrição Gênica
20.
Aging Dis ; 6(5): 400-5, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26425394

RESUMO

Aging can lead to decline in cognition, notably due to neurodegenerative processes overwhelming the brain over time. As people live longer, numerous concerns are rightfully raised toward long-term slowly incapacitating diseases with no cure, such as Alzheimer's disease. Since the early 2000's, the role of neuroinflammation has been scrutinized for its potential role in the development of diverse neurodegenerative diseases notably because of its slow onset and chronic nature in aging. Despite the lack of success yet, treatment of chronic neuroinflammation could help alleviate process implicated in neurodegenerative disease. A growing number of studies including our own have aimed at the endocannabinoid system and unfolded unique effects of this system on neuroinflammation, neurogenesis and hallmarks of Alzheimer's disease and made it a reasonable target in the context of normal and pathological brain aging.

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