Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.782
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
Cell ; 184(4): 1032-1046.e18, 2021 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-33571428

RESUMO

Human immunodeficiency virus (HIV-1) remains a major health threat. Viral capsid uncoating and nuclear import of the viral genome are critical for productive infection. The size of the HIV-1 capsid is generally believed to exceed the diameter of the nuclear pore complex (NPC), indicating that capsid uncoating has to occur prior to nuclear import. Here, we combined correlative light and electron microscopy with subtomogram averaging to capture the structural status of reverse transcription-competent HIV-1 complexes in infected T cells. We demonstrated that the diameter of the NPC in cellulo is sufficient for the import of apparently intact, cone-shaped capsids. Subsequent to nuclear import, we detected disrupted and empty capsid fragments, indicating that uncoating of the replication complex occurs by breaking the capsid open, and not by disassembly into individual subunits. Our data directly visualize a key step in HIV-1 replication and enhance our mechanistic understanding of the viral life cycle.


Assuntos
Capsídeo/metabolismo , HIV-1/metabolismo , Poro Nuclear/metabolismo , Transporte Ativo do Núcleo Celular , Capsídeo/ultraestrutura , Microscopia Crioeletrônica , Células HEK293 , Infecções por HIV/virologia , HIV-1/ultraestrutura , Humanos , Modelos Biológicos , Poro Nuclear/ultraestrutura , Poro Nuclear/virologia , Transcrição Reversa , Vírion/metabolismo , Internalização do Vírus , Fatores de Poliadenilação e Clivagem de mRNA/metabolismo
2.
Cell ; 178(3): 653-671.e19, 2019 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-31348890

RESUMO

Nociceptin and its receptor are widely distributed throughout the brain in regions associated with reward behavior, yet how and when they act is unknown. Here, we dissected the role of a nociceptin peptide circuit in reward seeking. We generated a prepronociceptin (Pnoc)-Cre mouse line that revealed a unique subpopulation of paranigral ventral tegmental area (pnVTA) neurons enriched in prepronociceptin. Fiber photometry recordings during progressive ratio operant behavior revealed pnVTAPnoc neurons become most active when mice stop seeking natural rewards. Selective pnVTAPnoc neuron ablation, inhibition, and conditional VTA nociceptin receptor (NOPR) deletion increased operant responding, revealing that the pnVTAPnoc nucleus and VTA NOPR signaling are necessary for regulating reward motivation. Additionally, optogenetic and chemogenetic activation of this pnVTAPnoc nucleus caused avoidance and decreased motivation for rewards. These findings provide insight into neuromodulatory circuits that regulate motivated behaviors through identification of a previously unknown neuropeptide-containing pnVTA nucleus that limits motivation for rewards.


Assuntos
Motivação/efeitos dos fármacos , Peptídeos Opioides/farmacologia , Recompensa , Área Tegmentar Ventral/metabolismo , Potenciais de Ação , Animais , Comportamento Animal/efeitos dos fármacos , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios/fisiologia , Técnicas de Patch-Clamp , Precursores de Proteínas/genética , Receptores Opioides/agonistas , Receptores Opioides/deficiência , Receptores Opioides/genética , Receptor de Nociceptina , Nociceptina
3.
Nature ; 611(7935): 312-319, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36261521

RESUMO

Infectious diseases are among the strongest selective pressures driving human evolution1,2. This includes the single greatest mortality event in recorded history, the first outbreak of the second pandemic of plague, commonly called the Black Death, which was caused by the bacterium Yersinia pestis3. This pandemic devastated Afro-Eurasia, killing up to 30-50% of the population4. To identify loci that may have been under selection during the Black Death, we characterized genetic variation around immune-related genes from 206 ancient DNA extracts, stemming from two different European populations before, during and after the Black Death. Immune loci are strongly enriched for highly differentiated sites relative to a set of non-immune loci, suggesting positive selection. We identify 245 variants that are highly differentiated within the London dataset, four of which were replicated in an independent cohort from Denmark, and represent the strongest candidates for positive selection. The selected allele for one of these variants, rs2549794, is associated with the production of a full-length (versus truncated) ERAP2 transcript, variation in cytokine response to Y. pestis and increased ability to control intracellular Y. pestis in macrophages. Finally, we show that protective variants overlap with alleles that are today associated with increased susceptibility to autoimmune diseases, providing empirical evidence for the role played by past pandemics in shaping present-day susceptibility to disease.


Assuntos
DNA Antigo , Predisposição Genética para Doença , Imunidade , Peste , Seleção Genética , Yersinia pestis , Humanos , Aminopeptidases/genética , Aminopeptidases/imunologia , Peste/genética , Peste/imunologia , Peste/microbiologia , Peste/mortalidade , Yersinia pestis/imunologia , Yersinia pestis/patogenicidade , Seleção Genética/imunologia , Europa (Continente)/epidemiologia , Europa (Continente)/etnologia , Imunidade/genética , Conjuntos de Dados como Assunto , Londres/epidemiologia , Dinamarca/epidemiologia
4.
Nature ; 598(7882): 646-651, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34646022

RESUMO

µ-Opioid peptide receptor (MOPR) stimulation alters respiration, analgesia and reward behaviour, and can induce substance abuse and overdose1-3. Despite its evident importance, the endogenous mechanisms for MOPR regulation of consummatory behaviour have remained unknown4. Here we report that endogenous MOPR regulation of reward consumption in mice acts through a specific dorsal raphe to nucleus accumbens projection. MOPR-mediated inhibition of raphe terminals is necessary and sufficient to determine consummatory response, while select enkephalin-containing nucleus accumbens ensembles are engaged prior to reward consumption, suggesting that local enkephalin release is the source of the endogenous MOPR ligand. Selective modulation of nucleus accumbens enkephalin neurons and CRISPR-Cas9-mediated disruption of enkephalin substantiate this finding. These results isolate a fundamental endogenous opioid circuit for state-dependent consumptive behaviour and suggest alternative mechanisms for opiate modulation of reward.


Assuntos
Analgésicos Opioides/farmacologia , Núcleo Accumbens/fisiologia , Receptores Opioides mu/fisiologia , Recompensa , Animais , Encefalinas , Feminino , Masculino , Camundongos , Camundongos Knockout
5.
Nature ; 589(7841): 287-292, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33268892

RESUMO

Cardiovascular disease (CVD) is the leading cause of mortality in the world, with most CVD-related deaths resulting from myocardial infarction or stroke. The main underlying cause of thrombosis and cardiovascular events is atherosclerosis, an inflammatory disease that can remain asymptomatic for long periods. There is an urgent need for therapeutic and diagnostic options in this area. Atherosclerotic plaques contain autoantibodies1,2, and there is a connection between atherosclerosis and autoimmunity3. However, the immunogenic trigger and the effects of the autoantibody response during atherosclerosis are not well understood3-5. Here we performed high-throughput single-cell analysis of the atherosclerosis-associated antibody repertoire. Antibody gene sequencing of more than 1,700 B cells from atherogenic Ldlr-/- and control mice identified 56 antibodies expressed by in-vivo-expanded clones of B lymphocytes in the context of atherosclerosis. One-third of the expanded antibodies were reactive against atherosclerotic plaques, indicating that various antigens in the lesion can trigger antibody responses. Deep proteomics analysis identified ALDH4A1, a mitochondrial dehydrogenase involved in proline metabolism, as a target antigen of one of these autoantibodies, A12. ALDH4A1 distribution is altered during atherosclerosis, and circulating ALDH4A1 is increased in mice and humans with atherosclerosis, supporting the potential use of ALDH4A1 as a disease biomarker. Infusion of A12 antibodies into Ldlr-/- mice delayed plaque formation and reduced circulating free cholesterol and LDL, suggesting that anti-ALDH4A1 antibodies can protect against atherosclerosis progression and might have therapeutic potential in CVD.


Assuntos
1-Pirrolina-5-Carboxilato Desidrogenase/imunologia , Aterosclerose/imunologia , Aterosclerose/prevenção & controle , Autoanticorpos/imunologia , Autoantígenos/imunologia , 1-Pirrolina-5-Carboxilato Desidrogenase/sangue , Animais , Aterosclerose/sangue , Aterosclerose/diagnóstico , Autoanticorpos/sangue , Autoanticorpos/genética , Autoantígenos/sangue , Autoimunidade , Linfócitos B/imunologia , Biomarcadores/sangue , Colesterol/sangue , Dieta Hiperlipídica , Modelos Animais de Doenças , Progressão da Doença , Humanos , Lipoproteínas LDL/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Placa Aterosclerótica/imunologia , Placa Aterosclerótica/patologia , Placa Aterosclerótica/prevenção & controle , Proteômica , Receptores de LDL/deficiência , Receptores de LDL/genética , Análise de Célula Única
6.
Nat Methods ; 20(2): 284-294, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36690741

RESUMO

Cryo-electron tomograms capture a wealth of structural information on the molecular constituents of cells and tissues. We present DeePiCt (deep picker in context), an open-source deep-learning framework for supervised segmentation and macromolecular complex localization in cryo-electron tomography. To train and benchmark DeePiCt on experimental data, we comprehensively annotated 20 tomograms of Schizosaccharomyces pombe for ribosomes, fatty acid synthases, membranes, nuclear pore complexes, organelles, and cytosol. By comparing DeePiCt to state-of-the-art approaches on this dataset, we show its unique ability to identify low-abundance and low-density complexes. We use DeePiCt to study compositionally distinct subpopulations of cellular ribosomes, with emphasis on their contextual association with mitochondria and the endoplasmic reticulum. Finally, applying pre-trained networks to a HeLa cell tomogram demonstrates that DeePiCt achieves high-quality predictions in unseen datasets from different biological species in a matter of minutes. The comprehensively annotated experimental data and pre-trained networks are provided for immediate use by the community.


Assuntos
Mitocôndrias , Ribossomos , Humanos , Células HeLa , Tomografia com Microscopia Eletrônica/métodos , Retículo Endoplasmático , Processamento de Imagem Assistida por Computador/métodos
7.
Nature ; 586(7831): 796-800, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32879490

RESUMO

Nuclear pore complexes (NPCs) fuse the inner and outer membranes of the nuclear envelope. They comprise hundreds of nucleoporins (Nups) that assemble into multiple subcomplexes and form large central channels for nucleocytoplasmic exchange1,2. How this architecture facilitates messenger RNA export, NPC biogenesis and turnover remains poorly understood. Here we combine in situ structural biology and integrative modelling with correlative light and electron microscopy and molecular perturbation to structurally analyse NPCs in intact Saccharomyces cerevisiae cells within the context of nuclear envelope remodelling. We find an in situ conformation and configuration of the Nup subcomplexes that was unexpected from the results of previous in vitro analyses. The configuration of the Nup159 complex appears critical to spatially accommodate its function as an mRNA export platform, and as a mediator of NPC turnover. The omega-shaped nuclear envelope herniae that accumulate in nup116Δ cells3 conceal partially assembled NPCs lacking multiple subcomplexes, including the Nup159 complex. Under conditions of starvation, herniae of a second type are formed that cytoplasmically expose NPCs. These results point to a model of NPC turnover in which NPC-containing vesicles bud off from the nuclear envelope before degradation by the autophagy machinery. Our study emphasizes the importance of investigating the structure-function relationship of macromolecular complexes in their cellular context.


Assuntos
Microscopia Crioeletrônica , Poro Nuclear/metabolismo , Poro Nuclear/ultraestrutura , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/ultraestrutura , Autofagia , Modelos Moleculares , Poro Nuclear/química , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Tomografia
8.
Nucleic Acids Res ; 52(7): e38, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38407446

RESUMO

The Infinium BeadChip is the most widely used DNA methylome assay technology for population-scale epigenome profiling. However, the standard workflow requires over 200 ng of input DNA, hindering its application to small cell-number samples, such as primordial germ cells. We developed experimental and analysis workflows to extend this technology to suboptimal input DNA conditions, including ultra-low input down to single cells. DNA preamplification significantly enhanced detection rates to over 50% in five-cell samples and ∼25% in single cells. Enzymatic conversion also substantially improved data quality. Computationally, we developed a method to model the background signal's influence on the DNA methylation level readings. The modified detection P-value calculation achieved higher sensitivities for low-input datasets and was validated in over 100 000 public diverse methylome profiles. We employed the optimized workflow to query the demethylation dynamics in mouse primordial germ cells available at low cell numbers. Our data revealed nuanced chromatin states, sex disparities, and the role of DNA methylation in transposable element regulation during germ cell development. Collectively, we present comprehensive experimental and computational solutions to extend this widely used methylation assay technology to applications with limited DNA.


Assuntos
Metilação de DNA , Análise de Célula Única , Animais , Feminino , Humanos , Masculino , Camundongos , Ilhas de CpG , DNA/genética , DNA/metabolismo , Epigenômica/métodos , Células Germinativas/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Análise de Célula Única/métodos
9.
Nat Chem Biol ; 19(8): 1004-1012, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37322153

RESUMO

5-methylcytosine (5mC) is the most important DNA modification in mammalian genomes. The ideal method for 5mC localization would be both nondestructive of DNA and direct, without requiring inference based on detection of unmodified cytosines. Here we present direct methylation sequencing (DM-Seq), a bisulfite-free method for profiling 5mC at single-base resolution using nanogram quantities of DNA. DM-Seq employs two key DNA-modifying enzymes: a neomorphic DNA methyltransferase and a DNA deaminase capable of precise discrimination between cytosine modification states. Coupling these activities with deaminase-resistant adapters enables accurate detection of only 5mC via a C-to-T transition in sequencing. By comparison, we uncover a PCR-related underdetection bias with the hybrid enzymatic-chemical TET-assisted pyridine borane sequencing approach. Importantly, we show that DM-Seq, unlike bisulfite sequencing, unmasks prognostically important CpGs in a clinical tumor sample by not confounding 5mC with 5-hydroxymethylcytosine. DM-Seq thus offers an all-enzymatic, nondestructive, faithful and direct method for the reading of 5mC alone.


Assuntos
5-Metilcitosina , Metilação de DNA , Animais , Citosina , DNA/genética , Análise de Sequência de DNA/métodos , Mamíferos/genética
10.
Immunity ; 45(6): 1205-1218, 2016 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-28002729

RESUMO

Inflammation triggers the differentiation of Ly6Chi monocytes into microbicidal macrophages or monocyte-derived dendritic cells (moDCs). Yet, it is unclear whether environmental inflammatory cues control the polarization of monocytes toward each of these fates or whether specialized monocyte progenitor subsets exist before inflammation. Here, we have shown that naive monocytes are phenotypically heterogeneous and contain an NR4A1- and Flt3L-independent, CCR2-dependent, Flt3+CD11c-MHCII+PU.1hi subset. This subset acted as a precursor for FcγRIII+PD-L2+CD209a+, GM-CSF-dependent moDCs but was distal from the DC lineage, as shown by fate-mapping experiments using Zbtb46. By contrast, Flt3-CD11c-MHCII-PU.1lo monocytes differentiated into FcγRIII+PD-L2-CD209a-iNOS+ macrophages upon microbial stimulation. Importantly, Sfpi1 haploinsufficiency genetically distinguished the precursor activities of monocytes toward moDCs or microbicidal macrophages. Indeed, Sfpi1+/- mice had reduced Flt3+CD11c-MHCII+ monocytes and GM-CSF-dependent FcγRIII+PD-L2+CD209a+ moDCs but generated iNOS+ macrophages more efficiently. Therefore, intercellular disparities of PU.1 expression within naive monocytes segregate progenitor activity for inflammatory iNOS+ macrophages or moDCs.


Assuntos
Diferenciação Celular/imunologia , Células Dendríticas/imunologia , Macrófagos/imunologia , Monócitos/imunologia , Transferência Adotiva , Animais , Antígenos Ly/imunologia , Separação Celular , Células Dendríticas/citologia , Citometria de Fluxo , Macrófagos/citologia , Camundongos , Monócitos/citologia , Óxido Nítrico Sintase Tipo II/imunologia , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase
11.
Nature ; 568(7753): 541-545, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30971820

RESUMO

Osteoclasts are multinucleated giant cells that resorb bone, ensuring development and continuous remodelling of the skeleton and the bone marrow haematopoietic niche. Defective osteoclast activity leads to osteopetrosis and bone marrow failure1-9, whereas excess activity can contribute to bone loss and osteoporosis10. Osteopetrosis can be partially treated by bone marrow transplantation in humans and mice11-18, consistent with a haematopoietic origin of osteoclasts13,16,19 and studies that suggest that they develop by fusion of monocytic precursors derived from haematopoietic stem cells in the presence of CSF1 and RANK ligand1,20. However, the developmental origin and lifespan of osteoclasts, and the mechanisms that ensure maintenance of osteoclast function throughout life in vivo remain largely unexplored. Here we report that osteoclasts that colonize fetal ossification centres originate from embryonic erythro-myeloid progenitors21,22. These erythro-myeloid progenitor-derived osteoclasts are required for normal bone development and tooth eruption. Yet, timely transfusion of haematopoietic-stem-cell-derived monocytic cells in newborn mice is sufficient to rescue bone development in early-onset autosomal recessive osteopetrosis. We also found that the postnatal maintenance of osteoclasts, bone mass and the bone marrow cavity involve iterative fusion of circulating blood monocytic cells with long-lived osteoclast syncytia. As a consequence, parabiosis or transfusion of monocytic cells results in long-term gene transfer in osteoclasts in the absence of haematopoietic-stem-cell chimerism, and can rescue an adult-onset osteopetrotic phenotype caused by cathepsin K deficiency23,24. In sum, our results identify the developmental origin of osteoclasts and a mechanism that controls their maintenance in bones after birth. These data suggest strategies to rescue osteoclast deficiency in osteopetrosis and to modulate osteoclast activity in vivo.


Assuntos
Células-Tronco Hematopoéticas/citologia , Osteoclastos/citologia , Osteoclastos/metabolismo , Osteopetrose/genética , Animais , Animais Recém-Nascidos , Desenvolvimento Ósseo , Feminino , Genes Recessivos , Masculino , Camundongos , Osteopetrose/patologia , Erupção Dentária
12.
Nature ; 576(7786): 223-227, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31802005

RESUMO

NASA's Parker Solar Probe mission1 recently plunged through the inner heliosphere of the Sun to its perihelia, about 24 million kilometres from the Sun. Previous studies farther from the Sun (performed mostly at a distance of 1 astronomical unit) indicate that solar energetic particles are accelerated from a few kiloelectronvolts up to near-relativistic energies via at least two processes: 'impulsive' events, which are usually associated with magnetic reconnection in solar flares and are typically enriched in electrons, helium-3 and heavier ions2, and 'gradual' events3,4, which are typically associated with large coronal-mass-ejection-driven shocks and compressions moving through the corona and inner solar wind and are the dominant source of protons with energies between 1 and 10 megaelectronvolts. However, some events show aspects of both processes and the electron-proton ratio is not bimodally distributed, as would be expected if there were only two possible processes5. These processes have been very difficult to resolve from prior observations, owing to the various transport effects that affect the energetic particle population en route to more distant spacecraft6. Here we report observations of the near-Sun energetic particle radiation environment over the first two orbits of the probe. We find a variety of energetic particle events accelerated both locally and remotely including by corotating interaction regions, impulsive events driven by acceleration near the Sun, and an event related to a coronal mass ejection. We provide direct observations of the energetic particle radiation environment in the region just above the corona of the Sun and directly explore the physics of particle acceleration and transport.

13.
PLoS Genet ; 18(8): e1010328, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35913999

RESUMO

FOXO transcription factors have been shown to regulate longevity in model organisms and are associated with longevity in humans. To gain insight into how FOXO functions to increase lifespan, we examined the subcellular localization of DAF-16 in C. elegans. We show that DAF-16 is localized to endosomes and that this endosomal localization is increased by the insulin-IGF signaling (IIS) pathway. Endosomal localization of DAF-16 is modulated by endosomal trafficking proteins. Disruption of the Rab GTPase activating protein TBC-2 increases endosomal localization of DAF-16, while inhibition of TBC-2 targets, RAB-5 or RAB-7 GTPases, decreases endosomal localization of DAF-16. Importantly, the amount of DAF-16 that is localized to endosomes has functional consequences as increasing endosomal localization through mutations in tbc-2 reduced the lifespan of long-lived daf-2 IGFR mutants, depleted their fat stores, and DAF-16 target gene expression. Overall, this work identifies endosomal localization as a mechanism regulating DAF-16 FOXO, which is important for its functions in metabolism and aging.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Proteínas Ativadoras de GTPase/metabolismo , Longevidade , Animais , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Fatores de Transcrição Forkhead/genética , Proteínas Ativadoras de GTPase/genética , Humanos , Insulina/metabolismo , Longevidade/genética , Mutação , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
14.
Proc Natl Acad Sci U S A ; 119(39): e2206292119, 2022 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-36122222

RESUMO

Understanding the pathways by which simple RNA viruses self-assemble from their coat proteins and RNA is of practical and fundamental interest. Although RNA-protein interactions are thought to play a critical role in the assembly, our understanding of their effects is limited because the assembly process is difficult to observe directly. We address this problem by using interferometric scattering microscopy, a sensitive optical technique with high dynamic range, to follow the in vitro assembly kinetics of more than 500 individual particles of brome mosaic virus (BMV)-for which RNA-protein interactions can be controlled by varying the ionic strength of the buffer. We find that when RNA-protein interactions are weak, BMV assembles by a nucleation-and-growth pathway in which a small cluster of RNA-bound proteins must exceed a critical size before additional proteins can bind. As the strength of RNA-protein interactions increases, the nucleation time becomes shorter and more narrowly distributed, but the time to grow a capsid after nucleation is largely unaffected. These results suggest that the nucleation rate is controlled by RNA-protein interactions, while the growth process is driven less by RNA-protein interactions and more by protein-protein interactions and intraprotein forces. The nucleated pathway observed with the plant virus BMV is strikingly similar to that previously observed with bacteriophage MS2, a phylogenetically distinct virus with a different host kingdom. These results raise the possibility that nucleated assembly pathways might be common to other RNA viruses.


Assuntos
Bromovirus , Vírus de RNA , Bromovirus/genética , Bromovirus/metabolismo , Capsídeo/metabolismo , Vírus de RNA/genética , RNA Viral/genética , RNA Viral/metabolismo , Vírion/genética , Vírion/metabolismo
15.
Nano Lett ; 24(22): 6553-6559, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38775731

RESUMO

New approaches such as selective area growth (SAG), where crystal growth is lithographically controlled, allow the integration of bottom-up grown semiconductor nanomaterials in large-scale classical and quantum nanoelectronics. This calls for assessment and optimization of the reproducibility between individual components. We quantify the structural and electronic statistical reproducibility within large arrays of nominally identical selective area growth InAs nanowires. The distribution of structural parameters is acquired through comprehensive atomic force microscopy studies and transmission electron microscopy. These are compared to the statistical distributions of the cryogenic electrical properties of 256 individual SAG nanowire field effect transistors addressed using cryogenic multiplexer circuits. Correlating measurements between successive thermal cycles allows distinguishing between the contributions of surface impurity scattering and fixed structural properties to device reproducibility. The results confirm the potential of SAG nanomaterials, and the methodologies for quantifying statistical metrics are essential for further optimization of reproducibility.

16.
Biochemistry ; 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-39352075

RESUMO

The protein periostin is a matricellular protein that is expressed in connective tissue. It is composed of five globular domains arranged in an elongated structure with an extensive disordered C-terminal tail. Periostin contains 11 cysteine residues, of which one is unpaired and the rest form five intramolecular disulfide bonds. Periostin plays an important role during wound healing and is also involved in driving the inflammatory state in atopic diseases. This study provides a comprehensive biochemical characterization of periostin in human skin and in dermal and pulmonary fibroblasts in vitro. Through the application of Western blotting, co-immunoprecipitation, and LC-MS/MS, we show for the first time that periostin is a disulfide-bonded homodimer and engages in a novel disulfide-bonded complex with fibronectin both in vivo and in vitro. This inherent characteristic of periostin holds the potential to redefine our approach to exploring and understanding its functional role in future research endeavors.

17.
J Biol Chem ; 299(4): 103023, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36805338

RESUMO

Raf kinase inhibitor protein (RKIP) is a multifunctional modulator of intracellular signal transduction. Although most of its functions have been considered cytosolic, we show here that the localization of RKIP is primarily nuclear in both growing and quiescent Madin-Darby canine kidney epithelial cells and in Cal-51 and BT-20 human breast cancer cells. We have identified a putative bipartite nuclear localization signal (NLS) in RKIP that maps to the surface of the protein surrounding a known regulatory region. Like classical NLS sequences, the putative NLS of RKIP is rich in arginine and lysine residues. Deletion of and point mutations in the putative NLS lead to decreased nuclear localization. Point mutation of all the basic residues in the putative NLS of RKIP particularly strongly reduces nuclear localization. We found consistent results in reexpression experiments with wildtype or mutant RKIP in RKIP-silenced cells. A fusion construct of the putative NLS of RKIP alone to a heterologous reporter protein leads to nuclear localization of the fusion protein, demonstrating that this sequence alone is sufficient for import into the nucleus. We found that RKIP interacts with the nuclear transport factor importin α in BT-20 and MDA-MB-231 human breast cancer cells, suggesting importin-mediated active nuclear translocation. Evaluating the biological function of nuclear localization of RKIP, we found that the presence of the putative NLS is important for the role of RKIP in mitotic checkpoint regulation in MCF-7 human breast cancer cells. Taken together, these findings suggest that a bipartite NLS in RKIP interacts with importin α for active transport of RKIP into the nucleus and that this process may be involved in the regulation of mitotic progression.


Assuntos
Sinais de Localização Nuclear , Proteína de Ligação a Fosfatidiletanolamina , alfa Carioferinas , Animais , Cães , Humanos , Transporte Ativo do Núcleo Celular , alfa Carioferinas/genética , alfa Carioferinas/metabolismo , Núcleo Celular/metabolismo , Sinais de Localização Nuclear/genética , Sinais de Localização Nuclear/metabolismo , Proteína de Ligação a Fosfatidiletanolamina/genética , Proteína de Ligação a Fosfatidiletanolamina/metabolismo , Células Madin Darby de Rim Canino
18.
Plant J ; 116(1): 38-57, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37329210

RESUMO

Cassava's storage roots represent one of the most important sources of nutritional carbohydrates worldwide. Particularly, smallholder farmers in sub-Saharan Africa depend on this crop plant, where resilient and yield-improved varieties are of vital importance to support steadily increasing populations. Aided by a growing understanding of the plant's metabolism and physiology, targeted improvement concepts already led to visible gains in recent years. To expand our knowledge and to contribute to these successes, we investigated storage roots of eight cassava genotypes with differential dry matter content from three successive field trials for their proteomic and metabolic profiles. At large, the metabolic focus in storage roots transitioned from cellular growth processes toward carbohydrate and nitrogen storage with increasing dry matter content. This is reflected in higher abundance of proteins related to nucleotide synthesis, protein turnover, and vacuolar energization in low starch genotypes, while proteins involved in sugar conversion and glycolysis were more prevalent in high dry matter genotypes. This shift in metabolic orientation was underlined by a clear transition from oxidative- to substrate-level phosphorylation in high dry matter genotypes. Our analyses highlight metabolic patterns that are consistently and quantitatively associated with high dry matter accumulation in cassava storage roots, providing fundamental understanding of cassava's metabolism as well as a data resource for targeted genetic improvement.


Assuntos
Manihot , Amido , Amido/metabolismo , Manihot/metabolismo , Proteômica , Fosforilação , Verduras/metabolismo , Genótipo , Estresse Oxidativo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo
19.
J Am Chem Soc ; 146(11): 7431-7438, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38446768

RESUMO

Wet-chemical oxidation of graphite in a mixture of sulfuric acid with a strong oxidizer, such as potassium permanganate, leads to the formation of graphene oxide with hydroxyl and epoxide groups as the major functional groups. Nevertheless, the reaction mechanism remains unclear and the source of oxygen is a subject of debate. It could theoretically originate from the oxidizer, water, or sulfuric acid. In this study, we employed 18O and 17O labeled reagents to experimentally elucidate the reaction mechanism and, thus, determine the origin of oxo-functional groups. Our findings reveal the multifaceted roles of sulfuric acid, acting as a dispersion medium, a dehydrating agent for potassium permanganate, and an intercalant. Additionally, it significantly acts as a source of oxygen next to manganese oxides. Through 17O solid-state magic-angle spinning (MAS) NMR experiments, we exclude water as a direct reaction partner during oxygenation. With labeling experiments, we conclude on mechanistic insights, which may be exploited for the synthesis of novel graphene derivatives.

20.
N Engl J Med ; 384(21): 2002-2013, 2021 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-33974366

RESUMO

BACKGROUND: Severe combined immunodeficiency due to adenosine deaminase (ADA) deficiency (ADA-SCID) is a rare and life-threatening primary immunodeficiency. METHODS: We treated 50 patients with ADA-SCID (30 in the United States and 20 in the United Kingdom) with an investigational gene therapy composed of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) transduced ex vivo with a self-inactivating lentiviral vector encoding human ADA. Data from the two U.S. studies (in which fresh and cryopreserved formulations were used) at 24 months of follow-up were analyzed alongside data from the U.K. study (in which a fresh formulation was used) at 36 months of follow-up. RESULTS: Overall survival was 100% in all studies up to 24 and 36 months. Event-free survival (in the absence of reinitiation of enzyme-replacement therapy or rescue allogeneic hematopoietic stem-cell transplantation) was 97% (U.S. studies) and 100% (U.K. study) at 12 months; 97% and 95%, respectively, at 24 months; and 95% (U.K. study) at 36 months. Engraftment of genetically modified HSPCs persisted in 29 of 30 patients in the U.S. studies and in 19 of 20 patients in the U.K. study. Patients had sustained metabolic detoxification and normalization of ADA activity levels. Immune reconstitution was robust, with 90% of the patients in the U.S. studies and 100% of those in the U.K. study discontinuing immunoglobulin-replacement therapy by 24 months and 36 months, respectively. No evidence of monoclonal expansion, leukoproliferative complications, or emergence of replication-competent lentivirus was noted, and no events of autoimmunity or graft-versus-host disease occurred. Most adverse events were of low grade. CONCLUSIONS: Treatment of ADA-SCID with ex vivo lentiviral HSPC gene therapy resulted in high overall and event-free survival with sustained ADA expression, metabolic correction, and functional immune reconstitution. (Funded by the National Institutes of Health and others; ClinicalTrials.gov numbers, NCT01852071, NCT02999984, and NCT01380990.).


Assuntos
Agamaglobulinemia/terapia , Terapia Genética/métodos , Vetores Genéticos , Transplante de Células-Tronco Hematopoéticas , Lentivirus/genética , Imunodeficiência Combinada Severa/terapia , Adenosina Desaminase/deficiência , Adolescente , Criança , Pré-Escolar , Terapia Genética/efeitos adversos , Humanos , Lactente , Contagem de Linfócitos , Intervalo Livre de Progressão , Estudos Prospectivos , Transplante Autólogo
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa