Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.654
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Cell ; 186(24): 5308-5327.e25, 2023 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-37922900

RESUMO

Mammalian oocytes are filled with poorly understood structures called cytoplasmic lattices. First discovered in the 1960s and speculated to correspond to mammalian yolk, ribosomal arrays, or intermediate filaments, their function has remained enigmatic to date. Here, we show that cytoplasmic lattices are sites where oocytes store essential proteins for early embryonic development. Using super-resolution light microscopy and cryoelectron tomography, we show that cytoplasmic lattices are composed of filaments with a high surface area, which contain PADI6 and subcortical maternal complex proteins. The lattices associate with many proteins critical for embryonic development, including proteins that control epigenetic reprogramming of the preimplantation embryo. Loss of cytoplasmic lattices by knocking out PADI6 or the subcortical maternal complex prevents the accumulation of these proteins and results in early embryonic arrest. Our work suggests that cytoplasmic lattices enrich maternally provided proteins to prevent their premature degradation and cellular activity, thereby enabling early mammalian development.


Assuntos
Oócitos , Proteínas , Gravidez , Animais , Feminino , Oócitos/metabolismo , Proteínas/metabolismo , Embrião de Mamíferos/metabolismo , Citoesqueleto , Ribossomos , Desenvolvimento Embrionário , Mamíferos
2.
Cell ; 171(1): 179-187.e10, 2017 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-28890085

RESUMO

Expression of many disease-related aggregation-prone proteins results in cytotoxicity and the formation of large intracellular inclusion bodies. To gain insight into the role of inclusions in pathology and the in situ structure of protein aggregates inside cells, we employ advanced cryo-electron tomography methods to analyze the structure of inclusions formed by polyglutamine (polyQ)-expanded huntingtin exon 1 within their intact cellular context. In primary mouse neurons and immortalized human cells, polyQ inclusions consist of amyloid-like fibrils that interact with cellular endomembranes, particularly of the endoplasmic reticulum (ER). Interactions with these fibrils lead to membrane deformation, the local impairment of ER organization, and profound alterations in ER membrane dynamics at the inclusion periphery. These results suggest that aberrant interactions between fibrils and endomembranes contribute to the deleterious cellular effects of protein aggregation. VIDEO ABSTRACT.


Assuntos
Doença de Huntington/patologia , Corpos de Inclusão/patologia , Neurônios/patologia , Neurônios/ultraestrutura , Peptídeos/metabolismo , Amiloide/química , Animais , Microscopia Crioeletrônica , Retículo Endoplasmático/metabolismo , Retículo Endoplasmático/patologia , Feminino , Células HeLa , Humanos , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Corpos de Inclusão/química , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Transmissão , Mutação , Agregação Patológica de Proteínas , Tomografia/métodos
3.
Mol Cell ; 84(10): 1980-1994.e8, 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38759629

RESUMO

Aggregation of proteins containing expanded polyglutamine (polyQ) repeats is the cytopathologic hallmark of a group of dominantly inherited neurodegenerative diseases, including Huntington's disease (HD). Huntingtin (Htt), the disease protein of HD, forms amyloid-like fibrils by liquid-to-solid phase transition. Macroautophagy has been proposed to clear polyQ aggregates, but the efficiency of aggrephagy is limited. Here, we used cryo-electron tomography to visualize the interactions of autophagosomes with polyQ aggregates in cultured cells in situ. We found that an amorphous aggregate phase exists next to the radially organized polyQ fibrils. Autophagosomes preferentially engulfed this amorphous material, mediated by interactions between the autophagy receptor p62/SQSTM1 and the non-fibrillar aggregate surface. In contrast, amyloid fibrils excluded p62 and evaded clearance, resulting in trapping of autophagic structures. These results suggest that the limited efficiency of autophagy in clearing polyQ aggregates is due to the inability of autophagosomes to interact productively with the non-deformable, fibrillar disease aggregates.


Assuntos
Amiloide , Autofagossomos , Autofagia , Proteína Huntingtina , Doença de Huntington , Peptídeos , Agregados Proteicos , Proteína Sequestossoma-1 , Peptídeos/metabolismo , Peptídeos/química , Peptídeos/genética , Humanos , Proteína Huntingtina/metabolismo , Proteína Huntingtina/genética , Proteína Huntingtina/química , Autofagossomos/metabolismo , Autofagossomos/ultraestrutura , Proteína Sequestossoma-1/metabolismo , Proteína Sequestossoma-1/genética , Amiloide/metabolismo , Amiloide/química , Amiloide/genética , Doença de Huntington/metabolismo , Doença de Huntington/genética , Doença de Huntington/patologia , Microscopia Crioeletrônica , Animais , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/genética
4.
Cell ; 163(7): 1692-701, 2015 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-26687357

RESUMO

Vesicular nucleo-cytoplasmic transport is becoming recognized as a general cellular mechanism for translocation of large cargoes across the nuclear envelope. Cargo is recruited, enveloped at the inner nuclear membrane (INM), and delivered by membrane fusion at the outer nuclear membrane. To understand the structural underpinning for this trafficking, we investigated nuclear egress of progeny herpesvirus capsids where capsid envelopment is mediated by two viral proteins, forming the nuclear egress complex (NEC). Using a multi-modal imaging approach, we visualized the NEC in situ forming coated vesicles of defined size. Cellular electron cryo-tomography revealed a protein layer showing two distinct hexagonal lattices at its membrane-proximal and membrane-distant faces, respectively. NEC coat architecture was determined by combining this information with integrative modeling using small-angle X-ray scattering data. The molecular arrangement of the NEC establishes the basic mechanism for budding and scission of tailored vesicles at the INM.


Assuntos
Transporte Ativo do Núcleo Celular , Capsídeo/metabolismo , Membrana Nuclear/metabolismo , Membrana Nuclear/ultraestrutura , Vesículas Transportadoras/ultraestrutura , Animais , Capsídeo/ultraestrutura , Chlorocebus aethiops , Microscopia Crioeletrônica , Tomografia com Microscopia Eletrônica , Herpesvirus Humano 1/metabolismo , Herpesvirus Suídeo 1/metabolismo , Membrana Nuclear/química , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Dímeros de Pirimidina , Espalhamento a Baixo Ângulo , Vesículas Transportadoras/metabolismo , Células Vero , Proteínas Virais/química , Proteínas Virais/metabolismo
5.
Nature ; 2024 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-39415007

RESUMO

The taste system controls many insect behaviours, yet little is known about how tastants are encoded in mosquitoes or how they regulate critical behaviours. Here we examine how taste stimuli are encoded by Aedes albopictus mosquitoes-a highly invasive disease vector-and how these cues influence biting, feeding and egg laying. We find that neurons of the labellum, the major taste organ of the head, differentially encode a wide variety of human and other cues. We identify three functional classes of taste sensilla with an expansive coding capacity. In addition to excitatory responses, we identify prevalent inhibitory responses, which are predictive of biting behaviour. Certain bitter compounds suppress physiological and behavioural responses to sugar, suggesting their use as potent stop signals against appetitive cues. Complex cues, including human sweat, nectar and egg-laying site water, elicit distinct response profiles from the neuronal repertoire. We identify key tastants on human skin and in sweat that synergistically promote biting behaviours. Transcriptomic profiling identifies taste receptors that could be targeted to disrupt behaviours. Our study sheds light on key features of the taste system that suggest new ways of manipulating chemosensory function and controlling mosquito vectors.

6.
Immunity ; 53(1): 217-232.e5, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32668225

RESUMO

B cells are capable of a wide range of effector functions including antibody secretion, antigen presentation, cytokine production, and generation of immunological memory. A consistent strategy for classifying human B cells by using surface molecules is essential to harness this functional diversity for clinical translation. We developed a highly multiplexed screen to quantify the co-expression of 351 surface molecules on millions of human B cells. We identified differentially expressed molecules and aligned their variance with isotype usage, VDJ sequence, metabolic profile, biosynthesis activity, and signaling response. Based on these analyses, we propose a classification scheme to segregate B cells from four lymphoid tissues into twelve unique subsets, including a CD45RB+CD27- early memory population, a class-switched CD39+ tonsil-resident population, and a CD19hiCD11c+ memory population that potently responds to immune activation. This classification framework and underlying datasets provide a resource for further investigations of human B cell identity and function.


Assuntos
Subpopulações de Linfócitos B/classificação , Subpopulações de Linfócitos B/imunologia , Isotipos de Imunoglobulinas/metabolismo , Proteínas de Membrana/metabolismo , 5'-Nucleotidase/metabolismo , Apirase/metabolismo , Antígeno CD11c/metabolismo , Feminino , Proteínas Ligadas por GPI/metabolismo , Humanos , Memória Imunológica/imunologia , Antígenos Comuns de Leucócito/metabolismo , Pessoa de Meia-Idade , Transdução de Sinais/imunologia , Receptor fas/metabolismo
7.
Nature ; 614(7946): 48-53, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36725994

RESUMO

Scattering of high energy particles from nucleons probes their structure, as was done in the experiments that established the non-zero size of the proton using electron beams1. The use of charged leptons as scattering probes enables measuring the distribution of electric charges, which is encoded in the vector form factors of the nucleon2. Scattering weakly interacting neutrinos gives the opportunity to measure both vector and axial vector form factors of the nucleon, providing an additional, complementary probe of their structure. The nucleon transition axial form factor, FA, can be measured from neutrino scattering from free nucleons, νµn → µ-p and [Formula: see text], as a function of the negative four-momentum transfer squared (Q2). Up to now, FA(Q2) has been extracted from the bound nucleons in neutrino-deuterium scattering3-9, which requires uncertain nuclear corrections10. Here we report the first high-statistics measurement, to our knowledge, of the [Formula: see text] cross-section from the hydrogen atom, using the plastic scintillator target of the MINERvA11 experiment, extracting FA from free proton targets and measuring the nucleon axial charge radius, rA, to be 0.73 ± 0.17 fm. The antineutrino-hydrogen scattering presented here can access the axial form factor without the need for nuclear theory corrections, and enables direct comparisons with the increasingly precise lattice quantum chromodynamics computations12-15. Finally, the tools developed for this analysis and the result presented are substantial advancements in our capabilities to understand the nucleon structure in the weak sector, and also help the current and future neutrino oscillation experiments16-20 to better constrain neutrino interaction models.

8.
N Engl J Med ; 390(15): 1382-1393, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38587239

RESUMO

BACKGROUND: The effects of temporary mechanical circulatory support with a microaxial flow pump on mortality among patients with ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock remains unclear. METHODS: In an international, multicenter, randomized trial, we assigned patients with STEMI and cardiogenic shock to receive a microaxial flow pump (Impella CP) plus standard care or standard care alone. The primary end point was death from any cause at 180 days. A composite safety end point was severe bleeding, limb ischemia, hemolysis, device failure, or worsening aortic regurgitation. RESULTS: A total of 360 patients underwent randomization, of whom 355 were included in the final analysis (179 in the microaxial-flow-pump group and 176 in the standard-care group). The median age of the patients was 67 years, and 79.2% were men. Death from any cause occurred in 82 of 179 patients (45.8%) in the microaxial-flow-pump group and in 103 of 176 patients (58.5%) in the standard-care group (hazard ratio, 0.74; 95% confidence interval [CI], 0.55 to 0.99; P = 0.04). A composite safety end-point event occurred in 43 patients (24.0%) in the microaxial-flow-pump group and in 11 (6.2%) in the standard-care group (relative risk, 4.74; 95% CI, 2.36 to 9.55). Renal-replacement therapy was administered to 75 patients (41.9%) in the microaxial-flow-pump group and to 47 patients (26.7%) in the standard-care group (relative risk, 1.98; 95% CI, 1.27 to 3.09). CONCLUSIONS: The routine use of a microaxial flow pump with standard care in the treatment of patients with STEMI-related cardiogenic shock led to a lower risk of death from any cause at 180 days than standard care alone. The incidence of a composite of adverse events was higher with the use of the microaxial flow pump. (Funded by the Danish Heart Foundation and Abiomed; DanGer Shock ClinicalTrials.gov number, NCT01633502.).


Assuntos
Coração Auxiliar , Infarto do Miocárdio com Supradesnível do Segmento ST , Choque Cardiogênico , Idoso , Feminino , Humanos , Masculino , Coração Auxiliar/efeitos adversos , Incidência , Choque Cardiogênico/etiologia , Choque Cardiogênico/mortalidade , Choque Cardiogênico/cirurgia , Infarto do Miocárdio com Supradesnível do Segmento ST/complicações , Infarto do Miocárdio com Supradesnível do Segmento ST/mortalidade , Infarto do Miocárdio com Supradesnível do Segmento ST/terapia , Resultado do Tratamento , Circulação Assistida/efeitos adversos , Circulação Assistida/instrumentação , Circulação Assistida/métodos
9.
Immunity ; 48(2): 380-395.e6, 2018 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-29426702

RESUMO

Individual reports suggest that the central nervous system (CNS) contains multiple immune cell types with diverse roles in tissue homeostasis, immune defense, and neurological diseases. It has been challenging to map leukocytes across the entire brain, and in particular in pathology, where phenotypic changes and influx of blood-derived cells prevent a clear distinction between reactive leukocyte populations. Here, we applied high-dimensional single-cell mass and fluorescence cytometry, in parallel with genetic fate mapping systems, to identify, locate, and characterize multiple distinct immune populations within the mammalian CNS. Using this approach, we revealed that microglia, several subsets of border-associated macrophages and dendritic cells coexist in the CNS at steady state and exhibit disease-specific transformations in the immune microenvironment during aging and in models of Alzheimer's disease and multiple sclerosis. Together, these data and the described framework provide a resource for the study of disease mechanisms, potential biomarkers, and therapeutic targets in CNS disease.


Assuntos
Envelhecimento/imunologia , Sistema Nervoso Central/imunologia , Leucócitos/imunologia , Macrófagos/imunologia , Animais , Células Dendríticas/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Microglia/imunologia , Doenças Neurodegenerativas/etiologia , Doenças Neurodegenerativas/imunologia , Análise de Célula Única
10.
Nature ; 584(7821): 364-367, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32814887

RESUMO

The centre of the Milky Way hosts several high-energy processes that have strongly affected the inner regions of our Galaxy. Activity from the super-massive black hole at the Galactic Centre, which is coincident with the radio source Sagittarius A*, and stellar feedback from the inner molecular ring1 expel matter and energy from the disk in the form of a galactic wind2. Multiphase gas has been observed within this outflow, including hot highly ionized3,4 (temperatures of about 106 kelvin), warm ionized5,6 (104 to 105 kelvin) and cool atomic7,8 (103 to 104 kelvin) gas. However, so far there has been no evidence of the cold dense molecular phase (10 to 100 kelvin). Here we report observations of molecular gas outflowing from the centre of our Galaxy. This cold material is associated with atomic hydrogen clouds travelling in the nuclear wind8. The morphology and the kinematics of the molecular gas, resolved on a scale of about one parsec, indicate that these clouds are mixing with the warmer medium and are possibly being disrupted. The data also suggest that the mass of the molecular gas outflow is not negligible and could affect the rate of star formation in the central regions of the Galaxy. The presence of this cold, dense and high-velocity gas is puzzling, because neither Sagittarius A* at its current level of activity nor star formation in the inner Galaxy seems to be a viable source for this material.

11.
Proc Natl Acad Sci U S A ; 119(31): e2202070119, 2022 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-35881803

RESUMO

A contemporary research agenda in behavioral economics and neuroeconomics aims to identify individual differences and (neuro)psychological correlates of rationality. This research has been widely received in important interdisciplinary and field outlets. However, the psychometric reliability of such measurements of rationality has been presumed without enough methodological scrutiny. Drawing from multiple original and published datasets (in total over 1,600 participants), we unequivocally show that contemporary measurements of rationality have moderate to poor reliability according to common standards. Further analyses of the variance components, as well as a allowing participants to revise previous choices, suggest that this is driven by low between-subject variance rather than high measurement error. As has been argued previously for other behavioral measurements, this poses a challenge to the predominant correlational research designs and the search for sociodemographic or neural predictors. While our results draw a sobering picture of the prospects of contemporary measurements of rationality, they are not necessarily surprising from a theoretical perspective, which we outline in our discussion.


Assuntos
Tomada de Decisões , Economia Comportamental , Características Humanas , Psicometria , Humanos , Reprodutibilidade dos Testes
12.
Plant J ; 114(3): 683-698, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36840368

RESUMO

In this work, we identified and functionally characterized the strawberry (Fragaria × ananassa) R2R3 MYB transcription factor FaMYB123. As in most genes associated with organoleptic properties of ripe fruit, FaMYB123 expression is ripening-related, receptacle-specific, and antagonistically regulated by ABA and auxin. Knockdown of FaMYB123 expression by RNAi in ripe strawberry fruit receptacles downregulated the expression of enzymes involved in the late steps of anthocyanin/flavonoid biosynthesis. Transgenic fruits showed a parallel decrease in the contents of total anthocyanin and flavonoid, especially malonyl derivatives of pelargonidin and cyanidins. The decrease was concomitant with accumulation of proanthocyanin, propelargonidins, and other condensed tannins associated mainly with green receptacles. Potential coregulation between FaMYB123 and FaMYB10, which may act on different sets of genes for the enzymes involved in anthocyanin production, was explored. FaMYB123 and FabHLH3 were found to interact and to be involved in the transcriptional activation of FaMT1, a gene responsible for the malonylation of anthocyanin components during ripening. Taken together, these results demonstrate that FaMYB123 regulates the late steps of the flavonoid pathway in a specific manner. In this study, a new function for an R2R3 MYB transcription factor, regulating the expression of a gene that encodes a malonyltransferase, has been elucidated.


Assuntos
Fragaria , Proantocianidinas , Antocianinas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Flavonoides/metabolismo , Proantocianidinas/metabolismo , Flavonóis/metabolismo , Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fragaria/genética , Fragaria/metabolismo
13.
J Am Chem Soc ; 146(42): 28895-28905, 2024 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-39381921

RESUMO

Colloidal quantum dots (QDs) with a wide color gamut and high luminescent efficiency are promising for next-generation electronic and photonic devices. However, precise and scalable patterning of QDs without degrading their properties and their integration into commercially relevant devices, such as digitally addressable QD light-emitting diode (QLED) displays, remain challenging. Here, we develop electronically optimized diazirine-based cross-linkers for nondestructive, direct photopatterning of QDs and, ultimately, building the active-matrix QLED displays. The key to the cross-linker design is the introduction of electron-donating substituents that permit the formation of ground-state singlet carbenes for air-stable and benign QD photopatterning. Under ambient conditions, these cross-linkers enable the patterning of heavy metal-free QDs at a resolution of over 13,000 pixels per inch using commercial i-line photolithography. The patterned QD layers fully preserved their optical and optoelectronic properties. Pixelated electroluminescent devices with patterned InP/ZnSe/ZnS QD layers show a peak external quantum efficiency of 15.3% and a maximum luminance of about 40,000 cd m-2, outperforming those made by existing QD patterning approaches. We further show the seamless integration of patterned QLEDs with thin-film transistor circuits and the fabrication of dual-color active-matrix displays. These results underscore the importance of designing photochemistry for QD patterning, and promise the implementation of direct photopatterning methods in manufacturing commercial QLED displays and other integrated QD device platforms.

14.
Int J Cancer ; 155(5): 785-799, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-38783577

RESUMO

Management of multiple primary lung cancer (MPLC) remains challenging, partly due to its increasing incidence, especially with the significant rise in cases of multiple lung nodules caused by low-dose computed tomography screening. Moreover, the indefinite pathogenesis, diagnostic criteria, and treatment selection add to the complexity. In recent years, there have been continuous efforts to dissect the molecular characteristics of MPLC and explore new diagnostic approaches as well as treatment modalities, which will be reviewed here, with a focus on newly emerging evidence and future perspectives, hope to provide new insights into the management of MPLC and serve as inspiration for future research related to MPLC.


Assuntos
Neoplasias Pulmonares , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/terapia , Neoplasias Pulmonares/patologia , Neoplasias Primárias Múltiplas/patologia , Neoplasias Primárias Múltiplas/terapia , Tomografia Computadorizada por Raios X/métodos
15.
N Engl J Med ; 384(2): 105-116, 2021 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-33185990

RESUMO

BACKGROUND: The selective cardiac myosin activator omecamtiv mecarbil has been shown to improve cardiac function in patients with heart failure with a reduced ejection fraction. Its effect on cardiovascular outcomes is unknown. METHODS: We randomly assigned 8256 patients (inpatients and outpatients) with symptomatic chronic heart failure and an ejection fraction of 35% or less to receive omecamtiv mecarbil (using pharmacokinetic-guided doses of 25 mg, 37.5 mg, or 50 mg twice daily) or placebo, in addition to standard heart-failure therapy. The primary outcome was a composite of a first heart-failure event (hospitalization or urgent visit for heart failure) or death from cardiovascular causes. RESULTS: During a median of 21.8 months, a primary-outcome event occurred in 1523 of 4120 patients (37.0%) in the omecamtiv mecarbil group and in 1607 of 4112 patients (39.1%) in the placebo group (hazard ratio, 0.92; 95% confidence interval [CI], 0.86 to 0.99; P = 0.03). A total of 808 patients (19.6%) and 798 patients (19.4%), respectively, died from cardiovascular causes (hazard ratio, 1.01; 95% CI, 0.92 to 1.11). There was no significant difference between groups in the change from baseline on the Kansas City Cardiomyopathy Questionnaire total symptom score. At week 24, the change from baseline for the median N-terminal pro-B-type natriuretic peptide level was 10% lower in the omecamtiv mecarbil group than in the placebo group; the median cardiac troponin I level was 4 ng per liter higher. The frequency of cardiac ischemic and ventricular arrhythmia events was similar in the two groups. CONCLUSIONS: Among patients with heart failure and a reduced ejection, those who received omecamtiv mecarbil had a lower incidence of a composite of a heart-failure event or death from cardiovascular causes than those who received placebo. (Funded by Amgen and others; GALACTIC-HF ClinicalTrials.gov number, NCT02929329; EudraCT number, 2016-002299-28.).


Assuntos
Miosinas Cardíacas/metabolismo , Cardiotônicos/uso terapêutico , Insuficiência Cardíaca Sistólica/tratamento farmacológico , Ureia/análogos & derivados , Idoso , Idoso de 80 Anos ou mais , Miosinas Cardíacas/efeitos dos fármacos , Cardiotônicos/efeitos adversos , Cardiotônicos/farmacologia , Doenças Cardiovasculares/mortalidade , Feminino , Insuficiência Cardíaca Sistólica/metabolismo , Insuficiência Cardíaca Sistólica/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Contração Miocárdica/efeitos dos fármacos , Volume Sistólico , Ureia/efeitos adversos , Ureia/farmacologia , Ureia/uso terapêutico
16.
PLoS Pathog ; 18(8): e1010575, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35925870

RESUMO

Human Cytomegalovirus (HCMV) can infect a variety of cell types by using virions of varying glycoprotein compositions. It is still unclear how this diversity is generated, but spatio-temporally separated envelopment and egress pathways might play a role. So far, one egress pathway has been described in which HCMV particles are individually enveloped into small vesicles and are subsequently exocytosed continuously. However, some studies have also found enveloped virus particles inside multivesicular structures but could not link them to productive egress or degradation pathways. We used a novel 3D-CLEM workflow allowing us to investigate these structures in HCMV morphogenesis and egress at high spatio-temporal resolution. We found that multiple envelopment events occurred at individual vesicles leading to multiviral bodies (MViBs), which subsequently traversed the cytoplasm to release virions as intermittent bulk pulses at the plasma membrane to form extracellular virus accumulations (EVAs). Our data support the existence of a novel bona fide HCMV egress pathway, which opens the gate to evaluate divergent egress pathways in generating virion diversity.


Assuntos
Citomegalovirus , Montagem de Vírus , Citoplasma/metabolismo , Humanos , Vírion
17.
Appl Environ Microbiol ; 90(2): e0136923, 2024 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-38236067

RESUMO

The degree of cyclization, or ring index (RI), in archaeal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids was long thought to reflect homeoviscous adaptation to temperature. However, more recent experiments show that other factors (e.g., pH, growth phase, and energy flux) can also affect membrane composition. The main objective of this study was to investigate the effect of carbon and energy metabolism on membrane cyclization. To do so, we cultivated Acidianus sp. DS80, a metabolically flexible and thermoacidophilic archaeon, on different electron donor, acceptor, and carbon source combinations (S0/Fe3+/CO2, H2/Fe3+/CO2, H2/S0/CO2, or H2/S0/glucose). We show that differences in energy and carbon metabolism can result in over a full unit of change in RI in the thermoacidophile Acidianus sp. DS80. The patterns in RI correlated with the normalized electron transfer rate between the electron donor and acceptor and did not always align with thermodynamic predictions of energy yield. In light of this, we discuss other factors that may affect the kinetics of cellular energy metabolism: electron transfer chain (ETC) efficiency, location of ETC reaction components (cytoplasmic vs. extracellular), and the physical state of electron donors and acceptors (gas vs. solid). Furthermore, the assimilation of a more reduced form of carbon during heterotrophy appears to decrease the demand for reducing equivalents during lipid biosynthesis, resulting in lower RI. Together, these results point to the fundamental role of the cellular energy state in dictating GDGT cyclization, with those cells experiencing greater energy limitation synthesizing more cyclized GDGTs.IMPORTANCESome archaea make unique membrane-spanning lipids with different numbers of five- or six-membered rings in the core structure, which modulate membrane fluidity and permeability. Changes in membrane core lipid composition reflect the fundamental adaptation strategies of archaea in response to stress, but multiple environmental and physiological factors may affect the needs for membrane fluidity and permeability. In this study, we tested how Acidianus sp. DS80 changed its core lipid composition when grown with different electron donor/acceptor pairs. We show that changes in energy and carbon metabolisms significantly affected the relative abundance of rings in the core lipids of DS80. These observations highlight the need to better constrain metabolic parameters, in addition to environmental factors, which may influence changes in membrane physiology in Archaea. Such consideration would be particularly important for studying archaeal lipids from habitats that experience frequent environmental fluctuations and/or where metabolically diverse archaea thrive.


Assuntos
Acidianus , Acidianus/metabolismo , Glicerol/metabolismo , Dióxido de Carbono/metabolismo , Lipídeos de Membrana/metabolismo , Archaea/metabolismo , Metabolismo Energético
18.
J Card Fail ; 30(6): 755-763, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38215932

RESUMO

BACKGROUND: Omecamtiv mecarbil improves outcomes in patients with heart failure and reduced ejection fraction (HFrEF). We examined the relationship between baseline troponin levels, change in troponin levels over time and the treatment effect of omecamtiv mecarbil in patients enrolled in the Global Approach to Lowering Adverse Cardiac Outcomes through Improving Contractility in Heart Failure (GALACTIC-HF) trial (NCT02929329). METHODS: GALACTIC-HF was a double-blind, placebo-controlled trial that randomized 8256 patients with symptomatic HFrEF to omecamtiv mecarbil or placebo. High-sensitivity troponin I (cTnI) was measured serially at a core laboratory. We analyzed the relationship between both baseline cTnI and change in cTnI concentrations with clinical outcomes and the treatment effect of omecamtiv mecarbil. RESULTS: Higher baseline cTnI concentrations were associated with a risk of adverse outcomes (hazard ratio for the primary endpoint of time to first HF event or CV death = 1.30; 95% CI 1.28, 1.33; P < 0.001 per doubling of baseline cTnI). Although the incidence of safety outcomes was higher in patients with higher baseline cTnI, there was no difference between treatment groups. Treatment with omecamtiv mecarbil led to a modest increase in cTnI that was related to plasma concentrations of omecamtiv mecarbil, and it peaked at 6 weeks. An increase in troponin from baseline to week 6 was associated with an increased risk of the primary endpoint (P < 0.001), which was similar, regardless of treatment assignment (P value for interaction = 0.2). CONCLUSIONS: In a cohort of patients with HFrEF, baseline cTnI concentrations were strongly associated with adverse clinical outcomes. Although cTnI concentrations were higher in patients treated with omecamtiv mecarbil, we did not find a differential effect of omecamtiv mecarbil on either safety or efficacy based on baseline cTnI status or change in cTnI.


Assuntos
Biomarcadores , Insuficiência Cardíaca , Volume Sistólico , Troponina I , Humanos , Masculino , Método Duplo-Cego , Feminino , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/sangue , Pessoa de Meia-Idade , Idoso , Troponina I/sangue , Resultado do Tratamento , Volume Sistólico/efeitos dos fármacos , Biomarcadores/sangue , Ureia/análogos & derivados , Ureia/uso terapêutico , Ureia/farmacologia , Carbamatos/uso terapêutico
19.
J Exp Bot ; 2024 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-39387692

RESUMO

Adenine metabolism is important for common bean (Phaseolus vulgaris L) productivity since this legume uses ureides derived from the oxidation of purine nucleotides, as their primary nitrogen storage molecules. Purine nucleotides are produced from de novo synthesis or through salvage pathways. Adenine phosphoribosyl transferase (APRT) is the enzyme dedicated to adenine nucleobase salvage for nucleotide synthesis, but it also acts on the inactivation of cytokinin bases. In common bean, the APRT enzyme is encoded by four genes. Gene expression analysis, biochemical properties and subcellular location suggest functional differences among the common bean APRT isoforms. CRISPR/Cas9 targeted downregulation of two of the four PvAPRTs followed by metabolomics and physiological analyses of targeted hairy roots reveals that, although the two proteins have redundant functions, PvAPRT1 mostly participates in the salvage of adenine, whereas PvAPRT5 is the predominant form in the regulation of cytokinin homeostasis and stress responses with a high impact in root and nodule growth.

20.
Tumour Biol ; 46(s1): S219-S232, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-37840518

RESUMO

BACKGROUND: Despite successful response to first line therapy, patients with small-cell lung cancer (SCLC) often suffer from early relapses and disease progression. OBJECTIVE: To investigate the relevance of serum tumor markers for estimation of prognosis at several time points during the course of disease. METHODS: In a prospective, single-center study, serial assessments of progastrin-releasing peptide (ProGRP), neuron-specific enolase (NSE), cytokeratin-19 fragments (CYFRA 21-1) and carcino-embryogenic antigen (CEA) were performed during and after chemotherapy in 232 SCLC patients, and correlated with therapy response and overall survival (OS). RESULTS: ProGRP, NSE and CYFRA 21-1 levels decreased quickly after the first chemotherapy cycle and correlated well with the radiological response. Either as single markers or in combination they provided valuable prognostic information regarding OS at all timepoints investigated: prior to first-line therapy, after two treatment cycles in patients with successful response to first-line therapy, and prior to the start of second-line therapy. Furthermore, they were useful for continuous monitoring during and after therapy and often indicated progressive disease several months ahead of radiological changes. CONCLUSIONS: The results indicate the great potential of ProGRP, NSE and CYFRA 21-1 for estimating prognosis and monitoring of SCLC patients throughout the course of the disease.


Assuntos
Antineoplásicos , Neoplasias Pulmonares , Carcinoma de Pequenas Células do Pulmão , Humanos , Carcinoma de Pequenas Células do Pulmão/tratamento farmacológico , Queratina-19 , Neoplasias Pulmonares/patologia , Biomarcadores Tumorais , Prognóstico , Estudos Prospectivos , Fragmentos de Peptídeos , Antígenos de Neoplasias , Fosfopiruvato Hidratase/uso terapêutico , Antineoplásicos/uso terapêutico , Proteínas Recombinantes
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA