Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 33
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Nat Metab ; 6(7): 1294-1309, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38858597

RESUMO

Downregulation of the urea cycle enzyme argininosuccinate synthase (ASS1) in multiple tumors is associated with a poor prognosis partly because of the metabolic diversion of cytosolic aspartate for pyrimidine synthesis, supporting proliferation and mutagenesis owing to nucleotide imbalance. Here, we find that prolonged loss of ASS1 promotes DNA damage in colon cancer cells and fibroblasts from subjects with citrullinemia type I. Following acute induction of DNA damage with doxorubicin, ASS1 expression is elevated in the cytosol and the nucleus with at least a partial dependency on p53; ASS1 metabolically restrains cell cycle progression in the cytosol by restricting nucleotide synthesis. In the nucleus, ASS1 and ASL generate fumarate for the succination of SMARCC1, destabilizing the chromatin-remodeling complex SMARCC1-SNF5 to decrease gene transcription, specifically in a subset of the p53-regulated cell cycle genes. Thus, following DNA damage, ASS1 is part of the p53 network that pauses cell cycle progression, enabling genome maintenance and survival. Loss of ASS1 contributes to DNA damage and promotes cell cycle progression, likely contributing to cancer mutagenesis and, hence, adaptability potential.


Assuntos
Argininossuccinato Sintase , Núcleo Celular , Citosol , Dano ao DNA , Proteína Supressora de Tumor p53 , Humanos , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/genética , Citosol/metabolismo , Argininossuccinato Sintase/metabolismo , Argininossuccinato Sintase/genética , Núcleo Celular/metabolismo , Ciclo Celular/genética
2.
Sci Immunol ; 9(91): eabq6930, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38215193

RESUMO

The thymus is a primary lymphoid organ that is essential for the establishment of adaptive immunity through generation of immunocompetent T cells. In response to various stress signals, the thymus undergoes acute but reversible involution. However, the mechanisms governing its recovery are incompletely understood. Here, we used a dexamethasone-induced acute thymic involution mouse model to investigate how thymic hematopoietic cells (excluding T cells) contribute to thymic regeneration. scRNA-seq analysis revealed marked transcriptional and cellular changes in various thymic populations and highlighted thymus-resident innate lymphoid cells type 2 (ILC2) as a key cell type involved in the response to damage. We identified that ILC2 are activated by the alarmins IL-25 and IL-33 produced in response to tissue damage by thymic tuft cells and fibroblasts, respectively. Moreover, using mouse models deficient in either tuft cells and/or IL-33, we found that these alarmins are required for effective thymus regeneration after dexamethasone-induced damage. We also demonstrate that upon their damage-dependent activation, thymic ILC2 produce several effector molecules linked to tissue regeneration, such as amphiregulin and IL-13, which in turn promote thymic epithelial cell differentiation. Collectively, our study elucidates a previously undescribed role for thymic tuft cells and fibroblasts in thymus regeneration through activation of the type 2 immune response.


Assuntos
Imunidade Inata , Interleucina-33 , Camundongos , Animais , Linfócitos , Células em Tufo , Alarminas , Modelos Animais de Doenças , Fibroblastos , Dexametasona/farmacologia
3.
Methods Mol Biol ; 2713: 481-503, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-37639143

RESUMO

Macrophages represent a broad spectrum of distinct, but closely related tissue-resident immune cells. This presents a major challenge for the study of functional aspects of these cells using classical Cre recombinase-mediated conditional mutagenesis in mice, since single promoter-driven Cre transgenic models often display limited specificity toward their intended target. The advent of CRISPR/Cas9 technology has now provided a time- and cost-effective method to explore the full potential of binary transgenic, intersectional genetics. Specifically, the use of two promoters driving inactive Cre fragments that, when co-expressed, dimerize and only then gain recombinase activity allows the characterization and manipulation of genetically defined tissue macrophage subpopulations. Here, we will elaborate on the use of this protocol to capitalize on these recent technological advances in mouse genetics and discuss their strengths and pitfalls to improve the study of tissue macrophage subpopulations in physiology and pathophysiology.


Assuntos
Técnicas de Transferência de Genes , Macrófagos , Animais , Camundongos , Animais Geneticamente Modificados , Dimerização , Mutagênese
4.
bioRxiv ; 2023 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-38077050

RESUMO

Decreased intra-tumor heterogeneity (ITH) correlates with increased patient survival and immunotherapy response. However, even highly homogenous tumors may display variability in their aggressiveness, and how immunologic-factors impinge on their aggressiveness remains understudied. Here we studied the mechanisms responsible for the immune-escape of murine tumors with low ITH. We compared the temporal growth of homogeneous, genetically-similar single-cell clones that are rejected vs. those that are not-rejected after transplantation in-vivo using single-cell RNA sequencing and immunophenotyping. Non-rejected clones showed high infiltration of tumor-associated-macrophages (TAMs), lower T-cell infiltration, and increased T-cell exhaustion compared to rejected clones. Comparative analysis of rejection-associated gene expression programs, combined with in-vivo CRISPR knockout screens of candidate mediators, identified Mif (macrophage migration inhibitory factor) as a regulator of immune rejection. Mif knockout led to smaller tumors and reversed non-rejection-associated immune composition, particularly, leading to the reduction of immunosuppressive macrophage infiltration. Finally, we validated these results in melanoma patient data.

5.
Nature ; 622(7981): 164-172, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37674082

RESUMO

Development of immunocompetent T cells in the thymus is required for effective defence against all types of pathogens, including viruses, bacteria and fungi. To this end, T cells undergo a very strict educational program in the thymus, during which both non-functional and self-reactive T cell clones are eliminated by means of positive and negative selection1.Thymic epithelial cells (TECs) have an indispensable role in these processes, and previous studies have shown the notable heterogeneity of these cells2-7. Here, using multiomic analysis, we provide further insights into the functional and developmental diversity of TECs in mice, and reveal a detailed atlas of the TEC compartment according to cell transcriptional states and chromatin landscapes. Our analysis highlights unconventional TEC subsets that are similar to functionally well-defined parenchymal populations, including endocrine cells, microfold cells and myocytes. By focusing on the endocrine and microfold TEC populations, we show that endocrine TECs require Insm1 for their development and are crucial to maintaining thymus cellularity in a ghrelin-dependent manner; by contrast, microfold TECs require Spib for their development and are essential for the generation of thymic IgA+ plasma cells. Collectively, our study reveals that medullary TECs have the potential to differentiate into various types of molecularly distinct and functionally defined cells, which not only contribute to the induction of central tolerance, but also regulate the homeostasis of other thymus-resident populations.


Assuntos
Tolerância a Antígenos Próprios , Linfócitos T , Timo , Animais , Camundongos , Diferenciação Celular , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Tolerância a Antígenos Próprios/imunologia , Tolerância a Antígenos Próprios/fisiologia , Linfócitos T/classificação , Linfócitos T/citologia , Linfócitos T/imunologia , Timo/citologia , Timo/imunologia , Tecido Parenquimatoso , Células Musculares , Células Endócrinas , Cromatina , Transcrição Gênica , Grelina
6.
Front Immunol ; 13: 849701, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35911772

RESUMO

Breast tumors and their derived circulating cancer cells express the leukocyte ß2 integrin ligand Intercellular adhesion molecule 1 (ICAM-1). We found that elevated ICAM-1 expression in breast cancer cells results in a favorable outcome and prolonged survival of breast cancer patients. We therefore assessed the direct in vivo contribution of ICAM-1 expressed by breast cancer cells to breast tumorigenesis and lung metastasis in syngeneic immunocompetent mice hosts using spontaneous and experimental models of the lung metastasis of the C57BL/6-derived E0771 cell line, a luminal B breast cancer subtype. Notably, the presence of ICAM-1 on E0771 did not alter tumor growth or the leukocyte composition in the tumor microenvironment. Interestingly, the elimination of Tregs led to the rapid killing of primary tumor cells independently of tumor ICAM-1 expression. The in vivo elimination of a primary E0771 tumor expressing the ovalbumin (OVA) model neoantigen by the OVA-specific OVA-tcr-I mice (OT-I) transgenic cytotoxic T lymphocytes (CTLs) also took place normally in the absence of ICAM-1 expression by E0771 breast cancer target cells. The whole lung imaging of these cells by light sheet microscopy (LSM) revealed that both Wild type (WT)- and ICAM-1-deficient E0771 cells were equally disseminated from resected tumors and accumulated inside the lung vasculature at similar magnitudes. ICAM-1-deficient breast cancer cells developed, however, much larger metastatic lesions than their control counterparts. Strikingly, the vast majority of these cells gave rise to intravascular tumor colonies both in spontaneous and experimental metastasis models. In the latter model, ICAM-1 expressing E0771- but not their ICAM-1-deficient counterparts were highly susceptible to elimination by neutrophils adoptively transferred from E0771 tumor-bearing donor mice. Ex vivo, neutrophils derived from tumor-bearing mice also killed cultured E0771 cells via ICAM-1-dependent interactions. Collectively, our results are a first indication that ICAM-1 expressed by metastatic breast cancer cells that expand inside the lung vasculature is involved in innate rather than in adaptive cancer cell killing. This is also a first indication that the breast tumor expression of ICAM-1 is not required for CTL-mediated killing but can function as a suppressor of intravascular breast cancer metastasis to lungs.


Assuntos
Neoplasias Pulmonares , Linfócitos T Citotóxicos , Animais , Linhagem Celular Tumoral , Molécula 1 de Adesão Intercelular/metabolismo , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Endogâmicos C57BL , Ovalbumina , Microambiente Tumoral
7.
Sci Immunol ; 7(74): eabn8144, 2022 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-36026441

RESUMO

FOXN1 is a transcription factor critical for the development of both thymic epithelial cell (TEC) and hair follicle cell (HFC) compartments. However, mechanisms controlling its expression remain poorly understood. To address this question, we performed thorough analyses of the evolutionary conservation and chromatin status of the Foxn1 locus in different tissues and states and identified several putative cis-regulatory regions unique to TECs versus HFCs. Furthermore, experiments using genetically modified mice with specific deletions in the Foxn1 locus and additional bioinformatic analyses helped us identify key regions and transcription factors involved in either positive or negative regulation of Foxn1 in both TECs and HFCs. Specifically, we identified SIX1 and FOXN1 itself as key factors inducing Foxn1 expression in embryonic and neonatal TECs. Together, our data provide important mechanistic insights into the transcriptional regulation of the Foxn1 gene in TEC versus HFC and highlight the role of FOXN1 in its autoregulation.


Assuntos
Células Epiteliais , Regulação da Expressão Gênica , Animais , Camundongos , Proteínas de Ligação a RNA , Timo
8.
Nat Commun ; 13(1): 2800, 2022 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-35589715

RESUMO

The TP53 gene is mutated in approximately 60% of all colorectal cancer (CRC) cases. Over 20% of all TP53-mutated CRC tumors carry missense mutations at position R175 or R273. Here we report that CRC tumors harboring R273 mutations are more prone to progress to metastatic disease, with decreased survival, than those with R175 mutations. We identify a distinct transcriptional signature orchestrated by p53R273H, implicating activation of oncogenic signaling pathways and predicting worse outcome. These features are shared also with the hotspot mutants p53R248Q and p53R248W. p53R273H selectively promotes rapid CRC cell spreading, migration, invasion and metastasis. The transcriptional output of p53R273H is associated with preferential binding to regulatory elements of R273 signature genes. Thus, different TP53 missense mutations contribute differently to cancer progression. Elucidation of the differential impact of distinct TP53 mutations on disease features may make TP53 mutational information more actionable, holding potential for better precision-based medicine.


Assuntos
Neoplasias Colorretais , Proteína Supressora de Tumor p53 , Neoplasias Colorretais/genética , Genes p53 , Humanos , Mutação , Fenótipo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
9.
J Biol Chem ; 298(5): 101806, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35271851

RESUMO

Grass pea (Lathyrus sativus L.) is a grain legume commonly grown in Asia and Africa for food and forage. It is a highly nutritious and robust crop, capable of surviving both droughts and floods. However, it produces a neurotoxic compound, ß-N-oxalyl-L-α,ß-diaminopropionic acid (ß-ODAP), which can cause a severe neurological disorder when consumed as a primary diet component. While the catalytic activity associated with ß-ODAP formation was demonstrated more than 50 years ago, the enzyme responsible for this activity has not been identified. Here, we report on the identity, activity, 3D structure, and phylogenesis of this enzyme-ß-ODAP synthase (BOS). We show that BOS belongs to the benzylalcohol O-acetyltransferase, anthocyanin O-hydroxycinnamoyltransferase, anthranilate N-hydroxycinnamoyl/benzoyltransferase, deacetylvindoline 4-O-acetyltransferase superfamily of acyltransferases and is structurally similar to hydroxycinnamoyl transferase. Using molecular docking, we propose a mechanism for its catalytic activity, and using heterologous expression in tobacco leaves (Nicotiana benthamiana), we demonstrate that expression of BOS in the presence of its substrates is sufficient for ß-ODAP production in vivo. The identification of BOS may pave the way toward engineering ß-ODAP-free grass pea cultivars, which are safe for human and animal consumption.


Assuntos
Diamino Aminoácidos , Lathyrus/enzimologia , Neurotoxinas , Acetiltransferases , Diamino Aminoácidos/metabolismo , Simulação de Acoplamento Molecular
10.
EMBO J ; 40(20): e107158, 2021 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-34515347

RESUMO

Nucleolin is a multifunctional RNA Binding Protein (RBP) with diverse subcellular localizations, including the nucleolus in all eukaryotic cells, the plasma membrane in tumor cells, and the axon in neurons. Here we show that the glycine arginine rich (GAR) domain of nucleolin drives subcellular localization via protein-protein interactions with a kinesin light chain. In addition, GAR sequences mediate plasma membrane interactions of nucleolin. Both these modalities are in addition to the already reported involvement of the GAR domain in liquid-liquid phase separation in the nucleolus. Nucleolin transport to axons requires the GAR domain, and heterozygous GAR deletion mice reveal reduced axonal localization of nucleolin cargo mRNAs and enhanced sensory neuron growth. Thus, the GAR domain governs axonal transport of a growth controlling RNA-RBP complex in neurons, and is a versatile localization determinant for different subcellular compartments. Localization determination by GAR domains may explain why GAR mutants in diverse RBPs are associated with neurodegenerative disease.


Assuntos
Nucléolo Celular/metabolismo , Gânglios Espinais/metabolismo , Cinesinas/metabolismo , Neurônios/metabolismo , Fosfoproteínas/química , Proteínas de Ligação a RNA/química , Nervo Isquiático/metabolismo , Sequência de Aminoácidos , Animais , Transporte Axonal/genética , Linhagem Celular Tumoral , Nucléolo Celular/ultraestrutura , Gânglios Espinais/citologia , Expressão Gênica , Células HEK293 , Células HeLa , Humanos , Cinesinas/genética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Mutação , Neurônios/citologia , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Cultura Primária de Células , Domínios Proteicos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Nervo Isquiático/citologia , Nucleolina
11.
Front Microbiol ; 12: 688199, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34566902

RESUMO

Programmed cell death (PCD) in marine microalgae was suggested to be one of the mechanisms that facilitates bloom demise, yet its molecular components in phytoplankton are unknown. Phytoplankton are completely lacking any of the canonical components of PCD, such as caspases, but possess metacaspases. Metacaspases were shown to regulate PCD in plants and some protists, but their roles in algae and other organisms are still elusive. Here, we identified and biochemically characterized a type III metacaspase from the model diatom Phaeodactylum tricornutum, termed PtMCA-IIIc. Through expression of recombinant PtMCA-IIIc in E. coli, we revealed that PtMCA-IIIc exhibits a calcium-dependent protease activity, including auto-processing and cleavage after arginine. Similar metacaspase activity was detected in P. tricornutum cell extracts. PtMCA-IIIc overexpressing cells exhibited higher metacaspase activity, while CRISPR/Cas9-mediated knockout cells had decreased metacaspase activity compared to WT cells. Site-directed mutagenesis of cysteines that were predicted to form a disulfide bond decreased recombinant PtMCA-IIIc activity, suggesting its enhancement under oxidizing conditions. One of those cysteines was oxidized, detected in redox proteomics, specifically in response to lethal concentrations of hydrogen peroxide and a diatom derived aldehyde. Phylogenetic analysis revealed that this cysteine-pair is unique and widespread among diatom type III metacaspases. The characterization of a cell death associated protein in diatoms provides insights into the evolutionary origins of PCD and its ecological significance in algal bloom dynamics.

12.
Life Sci Alliance ; 3(4)2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32132179

RESUMO

Angiogenesis and lymphangiogenesis are key processes during embryogenesis as well as under physiological and pathological conditions. Vascular endothelial growth factor C (VEGFC), the ligand for both VEGFR2 and VEGFR3, is a central lymphangiogenic regulator that also drives angiogenesis. Here, we report that members of the highly conserved BACH (BTB and CNC homology) family of transcription factors regulate VEGFC expression, through direct binding to its promoter. Accordingly, down-regulation of bach2a hinders blood vessel formation and impairs lymphatic sprouting in a Vegfc-dependent manner during zebrafish embryonic development. In contrast, BACH1 overexpression enhances intratumoral blood vessel density and peritumoral lymphatic vessel diameter in ovarian and lung mouse tumor models. The effects on the vascular compartment correlate spatially and temporally with BACH1 transcriptional regulation of VEGFC expression. Altogether, our results uncover a novel role for the BACH/VEGFC signaling axis in lymphatic formation during embryogenesis and cancer, providing a novel potential target for therapeutic interventions.


Assuntos
Fatores de Transcrição de Zíper de Leucina Básica/genética , Proteínas de Grupos de Complementação da Anemia de Fanconi/genética , Neovascularização Fisiológica/fisiologia , Fator C de Crescimento do Endotélio Vascular/genética , Proteínas de Peixe-Zebra/genética , Moduladores da Angiogênese/metabolismo , Animais , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Linhagem Celular Tumoral , Proteínas de Grupos de Complementação da Anemia de Fanconi/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento/genética , Humanos , Linfangiogênese/fisiologia , Vasos Linfáticos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Nus , Morfogênese , Transdução de Sinais , Fator C de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 3 de Fatores de Crescimento do Endotélio Vascular/genética , Peixe-Zebra/embriologia , Proteínas de Peixe-Zebra/metabolismo
13.
Proc Natl Acad Sci U S A ; 116(33): 16489-16496, 2019 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-31346085

RESUMO

SLAMF9 belongs to the conserved lymphocytic activation molecule family (SLAMF). Unlike other SLAMs, which have been extensively studied, the role of SLAMF9 in the immune system remained mostly unexplored. By generating CRISPR/Cas9 SLAMF9 knockout mice, we analyzed the role of this receptor in plasmacytoid dendritic cells (pDCs), which preferentially express the SLAMF9 transcript and protein. These cells display a unique capacity to produce type I IFN and bridge between innate and adaptive immune response. Analysis of pDCs in SLAMF9-/- mice revealed an increase of immature pDCs in the bone marrow and enhanced accumulation of pDCs in the lymph nodes. In the periphery, SLAMF9 deficiency resulted in lower levels of the transcription factor SpiB, elevation of pDC survival, and attenuated IFN-α and TNF-α production. To define the role of SLAMF9 during inflammation, pDCs lacking SLAMF9 were followed during induced experimental autoimmune encephalomyelitis. SLAMF9-/- mice demonstrated attenuated disease and delayed onset, accompanied by a prominent increase of immature pDCs in the lymph node, with a reduced costimulatory potential and enhanced infiltration of pDCs into the central nervous system. These results suggest the crucial role of SLAMF9 in pDC differentiation, homeostasis, and function in the steady state and during experimental autoimmune encephalomyelitis.


Assuntos
Células Dendríticas/metabolismo , Doença , Saúde , Homeostase , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Animais , Medula Óssea/metabolismo , Diferenciação Celular , Regulação da Expressão Gênica , Linfonodos/metabolismo , Ativação Linfocitária/imunologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores CCR5/metabolismo , Família de Moléculas de Sinalização da Ativação Linfocitária/deficiência , Transcriptoma/genética
14.
Arterioscler Thromb Vasc Biol ; 39(8): 1602-1613, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31189431

RESUMO

OBJECTIVE: The early embryo implantation is characterized by enhanced uterine vascular permeability at the site of blastocyst attachment, followed by extracellular-matrix remodeling and angiogenesis. Two TG (transglutaminase) isoenzymes, TG2 (tissue TG) and FXIII (factor XIII), catalyze covalent cross-linking of the extracellular-matrix. However, their specific role during embryo implantation is not fully understood. Approach and Results: For mapping the distribution as well as the enzymatic activities of TG2 and FXIII towards blood-borne and resident extracellular-matrix substrates, we synthetized selective and specific low molecular weight substrate analogs for each of the isoenzymes. The implantation sites were challenged by genetically modifying the trophoblast cells in the outer layer of blastocysts, to either overexpress or deplete TG2 or FXIII, and the angiogenic response was studied by dynamic contrast-enhanced-magnetic resonance imaging. Dynamic contrast-enhanced-magnetic resonance imaging revealed a decrease in the permeability of decidual vasculature surrounding embryos in which FXIII were overexpressed in trophoblast cell. Reduction in decidual blood volume fraction was demonstrated when either FXIII or TG2 were overexpressed in embryonic trophoblast cell and was elevated when trophoblast cell was depleted of FXIII. These results were corroborated by histological analysis. CONCLUSIONS: In this study, we report on the isoenzyme-specific roles of TG2 and FXIII during the early days of mouse pregnancy and further reveal their involvement in decidual angiogenesis. Our results reveal an important magnetic resonance imaging-detectable function of embryo-derived TG2 and FXIII on regulating maternal angiogenesis during embryo implantation in mice.Visual Overview: An online visual overview is available for this article.


Assuntos
Implantação do Embrião/fisiologia , Fator XIII/fisiologia , Proteínas de Ligação ao GTP/fisiologia , Imageamento por Ressonância Magnética/métodos , Neovascularização Fisiológica/fisiologia , Transglutaminases/fisiologia , Animais , Feminino , Fibrinogênio/fisiologia , Camundongos , Gravidez , Proteína 2 Glutamina gama-Glutamiltransferase
15.
Nat Commun ; 9(1): 1596, 2018 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-29686286

RESUMO

Anorexia nervosa (AN) is a devastating eating disorder characterized by self-starvation that mainly affects women. Its etiology is unknown, which impedes successful treatment options leading to a limited chance of full recovery. Here, we show that gestation is a vulnerable window that can influence the predisposition to AN. By screening placental microRNA expression of naive and prenatally stressed (PNS) fetuses and assessing vulnerability to activity-based anorexia (ABA), we identify miR-340 as a sexually dimorphic regulator involved in prenatal programming of ABA. PNS caused gene-body hypermethylation of placental miR-340, which is associated with reduced miR-340 expression and increased protein levels of several target transcripts, GR, Cry2 and H3F3b. MiR-340 is linked to the expression of several nutrient transporters both in mice and human placentas. Using placenta-specific lentiviral transgenes and embryo transfer, we demonstrate the key role miR-340 plays in the mechanism involved in early life programming of ABA.


Assuntos
Anorexia Nervosa/genética , MicroRNAs/metabolismo , Placenta/metabolismo , Efeitos Tardios da Exposição Pré-Natal/genética , Adulto , Animais , Linhagem Celular Tumoral , Modelos Animais de Doenças , Transferência Embrionária , Feminino , Regulação da Expressão Gênica no Desenvolvimento/genética , Predisposição Genética para Doença , Humanos , Masculino , Troca Materno-Fetal , Camundongos , Camundongos Endogâmicos ICR , Camundongos Transgênicos , MicroRNAs/genética , Atividade Motora , Gravidez , Análise de Sequência de RNA , Fatores Sexuais
16.
Plant Cell Environ ; 40(10): 2381-2392, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28755442

RESUMO

The potato (Solanum tuberosum L.) tuber is a swollen underground stem that can sprout in an apical dominance (AD) pattern. Bromoethane (BE) induces loss of AD and the accumulation of vegetative vacuolar processing enzyme (S. tuberosum vacuolar processing enzyme [StVPE]) in the tuber apical meristem (TAM). Vacuolar processing enzyme activity, induced by BE, is followed by programmed cell death in the TAM. In this study, we found that the mature StVPE1 (mVPE) protein exhibits specific activity for caspase 1, but not caspase 3 substrates. Optimal activity of mVPE was achieved at acidic pH, consistent with localization of StVPE1 to the vacuole, at the edge of the TAM. Downregulation of StVPE1 by RNA interference resulted in reduced stem branching and retained AD in tubers treated with BE. Overexpression of StVPE1 fused to green fluorescent protein showed enhanced stem branching after BE treatment. Our data suggest that, following stress, induction of StVPE1 in the TAM induces AD loss and stem branching.


Assuntos
Apoptose , Cisteína Endopeptidases/metabolismo , Meristema/citologia , Meristema/enzimologia , Solanum tuberosum/enzimologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Caspase 1/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Inativação Gênica/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Hidrocarbonetos Bromados/farmacologia , Concentração de Íons de Hidrogênio , Meristema/efeitos dos fármacos , Meristema/genética , Tubérculos/efeitos dos fármacos , Tubérculos/enzimologia , Tubérculos/genética , Solanum tuberosum/efeitos dos fármacos , Solanum tuberosum/genética
17.
EMBO J ; 36(15): 2280-2295, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28607003

RESUMO

Cellular senescence is a permanent state of cell cycle arrest that protects the organism from tumorigenesis and regulates tissue integrity upon damage and during tissue remodeling. However, accumulation of senescent cells in tissues during aging contributes to age-related pathologies. A deeper understanding of the mechanisms regulating the viability of senescent cells is therefore required. Here, we show that the CDK inhibitor p21 (CDKN1A) maintains the viability of DNA damage-induced senescent cells. Upon p21 knockdown, senescent cells acquired multiple DNA lesions that activated ataxia telangiectasia mutated (ATM) and nuclear factor (NF)-κB kinase, leading to decreased cell survival. NF-κB activation induced TNF-α secretion and JNK activation to mediate death of senescent cells in a caspase- and JNK-dependent manner. Notably, p21 knockout in mice eliminated liver senescent stellate cells and alleviated liver fibrosis and collagen production. These findings define a novel pathway that regulates senescent cell viability and fibrosis.


Assuntos
Caspases/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Dano ao DNA , Regulação da Expressão Gênica , Sistema de Sinalização das MAP Quinases , Animais , Linhagem Celular , Sobrevivência Celular , Humanos , Camundongos
18.
Nat Immunol ; 18(2): 161-172, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27941786

RESUMO

Aire is a transcriptional regulator that induces promiscuous expression of thousands of genes encoding tissue-restricted antigens (TRAs) in medullary thymic epithelial cells (mTECs). While the target genes of Aire are well characterized, the transcriptional programs that regulate its own expression have remained elusive. Here we comprehensively analyzed both cis-acting and trans-acting regulatory mechanisms and found that the Aire locus was insulated by the global chromatin organizer CTCF and was hypermethylated in cells and tissues that did not express Aire. In mTECs, however, Aire expression was facilitated by concurrent eviction of CTCF, specific demethylation of exon 2 and the proximal promoter, and the coordinated action of several transcription activators, including Irf4, Irf8, Tbx21, Tcf7 and Ctcfl, which acted on mTEC-specific accessible regions in the Aire locus.


Assuntos
Células Epiteliais/imunologia , Redes Reguladoras de Genes , Linfócitos T/fisiologia , Timo/imunologia , Fatores de Transcrição/metabolismo , Animais , Apresentação de Antígeno/genética , Autoantígenos/metabolismo , Fator de Ligação a CCCTC , Diferenciação Celular , Células Cultivadas , Seleção Clonal Mediada por Antígeno , Metilação de DNA , Regulação da Expressão Gênica , Fatores Reguladores de Interferon/genética , Fatores Reguladores de Interferon/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Especificidade de Órgãos/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Proteínas com Domínio T/genética , Proteínas com Domínio T/metabolismo , Timo/citologia , Fatores de Transcrição/genética , Proteína AIRE
19.
Aging (Albany NY) ; 8(2): 328-44, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26878797

RESUMO

Cellular senescence is a stress response mechanism that limits tumorigenesis and tissue damage. Induction of cellular senescence commonly coincides with an immunogenic phenotype that promotes self-elimination by components of the immune system, thereby facilitating tumor suppression and limiting excess fibrosis during wound repair. The mechanisms by which senescent cells regulate their immune surveillance are not completely understood. Here we show that ligands of an activating Natural Killer (NK) cell receptor (NKG2D), MICA and ULBP2 are consistently up-regulated following induction of replicative senescence, oncogene-induced senescence and DNA damage - induced senescence. MICA and ULBP2 proteins are necessary for efficient NK-mediated cytotoxicity towards senescent fibroblasts. The mechanisms regulating the initial expression of NKG2D ligands in senescent cells are dependent on a DNA damage response, whilst continuous expression of these ligands is regulated by the ERK signaling pathway. In liver fibrosis, the accumulation of senescent activated stellate cells is increased in mice lacking NKG2D receptor leading to increased fibrosis. Overall, our results provide new insights into the mechanisms regulating the expression of immune ligands in senescent cells and reveal the importance of NKG2D receptor-ligand interaction in protecting against liver fibrosis.


Assuntos
Senescência Celular/imunologia , Vigilância Imunológica/imunologia , Subfamília K de Receptores Semelhantes a Lectina de Células NK/imunologia , Animais , Citometria de Fluxo , Imunofluorescência , Humanos , Células Matadoras Naturais , Ligantes , Cirrose Hepática/imunologia , Camundongos , Camundongos Knockout
20.
ISME J ; 10(7): 1742-54, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26784355

RESUMO

The cosmopolitan coccolithophore Emiliania huxleyi is a unicellular eukaryotic alga responsible for vast blooms in the ocean. These blooms have immense impact on large biogeochemical cycles and are terminated by a specific large double-stranded DNA E. huxleyi virus (EhV, Phycodnaviridae). EhV infection is accompanied by induction of hallmarks of programmed cell death and production of reactive oxygen species (ROS). Here we characterized alterations in ROS metabolism and explored its role during infection. Transcriptomic analysis of ROS-related genes predicted an increase in glutathione (GSH) and H2O2 production during infection. In accordance, using biochemical assays and specific fluorescent probes we demonstrated the overproduction of GSH during lytic infection. We also showed that H2O2 production, rather than superoxide, is the predominant ROS during the onset of the lytic phase of infection. Using flow cytometry, confocal microscopy and multispectral imaging flow cytometry, we showed that the profound co-production of H2O2 and GSH occurred in the same subpopulation of cells but at different subcellular localization. Positively stained cells for GSH and H2O2 were highly infected compared with negatively stained cells. Inhibition of ROS production by application of a peroxidase inhibitor or an H2O2 scavenger inhibited host cell death and reduced viral production. We conclude that viral infection induced remodeling of the host antioxidant network that is essential for a successful viral replication cycle. This study provides insight into viral replication strategy and suggests the use of specific cellular markers to identify and quantify the extent of active viral infection during E. huxleyi blooms in the ocean.


Assuntos
Antioxidantes/metabolismo , Haptófitas/virologia , Interações Hospedeiro-Patógeno , Phycodnaviridae/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Replicação Viral , Glutationa/metabolismo , Haptófitas/fisiologia , Peróxido de Hidrogênio/metabolismo , Oceanos e Mares , Oxirredução
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA