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1.
Nat Immunol ; 25(5): 755-763, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38641718

RESUMO

T cell infiltration into tumors is a favorable prognostic feature, but most solid tumors lack productive T cell responses. Mechanisms that coordinate T cell exclusion are incompletely understood. Here we identify hepatocyte activation via interleukin-6/STAT3 and secretion of serum amyloid A (SAA) proteins 1 and 2 as important regulators of T cell surveillance of extrahepatic tumors. Loss of STAT3 in hepatocytes or SAA remodeled the tumor microenvironment with infiltration by CD8+ T cells, while interleukin-6 overexpression in hepatocytes and SAA signaling via Toll-like receptor 2 reduced the number of intratumoral dendritic cells and, in doing so, inhibited T cell tumor infiltration. Genetic ablation of SAA enhanced survival after tumor resection in a T cell-dependent manner. Likewise, in individuals with pancreatic ductal adenocarcinoma, long-term survivors after surgery demonstrated lower serum SAA levels than short-term survivors. Taken together, these data define a fundamental link between liver and tumor immunobiology wherein hepatocytes govern productive T cell surveillance in cancer.


Assuntos
Linfócitos T CD8-Positivos , Hepatócitos , Interleucina-6 , Fator de Transcrição STAT3 , Proteína Amiloide A Sérica , Proteína Amiloide A Sérica/metabolismo , Proteína Amiloide A Sérica/genética , Hepatócitos/metabolismo , Hepatócitos/imunologia , Animais , Humanos , Camundongos , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Interleucina-6/metabolismo , Fator de Transcrição STAT3/metabolismo , Microambiente Tumoral/imunologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Evasão Tumoral , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Neoplasias Pancreáticas/imunologia , Neoplasias Pancreáticas/metabolismo , Transdução de Sinais , Carcinoma Ductal Pancreático/imunologia , Carcinoma Ductal Pancreático/patologia , Linfócitos do Interstício Tumoral/imunologia , Linfócitos do Interstício Tumoral/metabolismo , Linhagem Celular Tumoral
2.
Cell ; 183(3): 620-635.e22, 2020 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-33035454

RESUMO

Hippocampal activity represents many behaviorally important variables, including context, an animal's location within a given environmental context, time, and reward. Using longitudinal calcium imaging in mice, multiple large virtual environments, and differing reward contingencies, we derived a unified probabilistic model of CA1 representations centered on a single feature-the field propensity. Each cell's propensity governs how many place fields it has per unit space, predicts its reward-related activity, and is preserved across distinct environments and over months. Propensity is broadly distributed-with many low, and some very high, propensity cells-and thus strongly shapes hippocampal representations. This results in a range of spatial codes, from sparse to dense. Propensity varied ∼10-fold between adjacent cells in salt-and-pepper fashion, indicating substantial functional differences within a presumed cell type. Intracellular recordings linked propensity to cell excitability. The stability of each cell's propensity across conditions suggests this fundamental property has anatomical, transcriptional, and/or developmental origins.


Assuntos
Hipocampo/anatomia & histologia , Hipocampo/fisiologia , Animais , Comportamento Animal/fisiologia , Fenômenos Biofísicos , Cálcio/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Modelos Neurológicos , Células Piramidais/fisiologia , Recompensa , Análise e Desempenho de Tarefas , Fatores de Tempo
3.
Cell ; 173(6): 1468-1480.e9, 2018 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-29731167

RESUMO

The cell wall, a defining feature of plants, provides a rigid structure critical for bonding cells together. To overcome this physical constraint, plants must process cell wall linkages during growth and development. However, little is known about the mechanism guiding cell-cell detachment and cell wall remodeling. Here, we identify two neighboring cell types in Arabidopsis that coordinate their activities to control cell wall processing, thereby ensuring precise abscission to discard organs. One cell type produces a honeycomb structure of lignin, which acts as a mechanical "brace" to localize cell wall breakdown and spatially limit abscising cells. The second cell type undergoes transdifferentiation into epidermal cells, forming protective cuticle, demonstrating de novo specification of epidermal cells, previously thought to be restricted to embryogenesis. Loss of the lignin brace leads to inadequate cuticle formation, resulting in surface barrier defects and susceptible to infection. Together, we show how plants precisely accomplish abscission.


Assuntos
Arabidopsis/fisiologia , Parede Celular/metabolismo , Lignina/metabolismo , Proteínas de Arabidopsis/metabolismo , Diferenciação Celular , Membrana Celular/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Mutação , NADPH Oxidases/metabolismo , Plantas Geneticamente Modificadas/fisiologia , Pseudomonas syringae , Propriedades de Superfície
4.
Nature ; 619(7968): 78-86, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37407684

RESUMO

The paper-folding mechanism has been widely adopted in building of reconfigurable macroscale systems because of its unique capabilities and advantages in programming variable shapes and stiffness into a structure1-5. However, it has barely been exploited in the construction of molecular-level systems owing to the lack of a suitable design principle, even though various dynamic structures based on DNA self-assembly6-9 have been developed10-23. Here we propose a method to harness the paper-folding mechanism to create reconfigurable DNA origami structures. The main idea is to build a reference, planar wireframe structure24 whose edges follow a crease pattern in paper folding so that it can be folded into various target shapes. We realized several paper-like folding and unfolding patterns using DNA strand displacement25 with high yield. Orthogonal folding, repeatable folding and unfolding, folding-based microRNA detection and fluorescence signal control were demonstrated. Stimuli-responsive folding and unfolding triggered by pH or light-source change were also possible. Moreover, by employing hierarchical assembly26 we could expand the design space and complexity of the paper-folding mechanism in a highly programmable manner. Because of its high programmability and scalability, we expect that the proposed paper-folding-based reconfiguration method will advance the development of complex molecular systems.


Assuntos
DNA , Conformação de Ácido Nucleico , DNA/química , MicroRNAs/análise , MicroRNAs/química , Fluorescência , Concentração de Íons de Hidrogênio
5.
Mol Cell ; 81(18): 3820-3832.e7, 2021 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-34233158

RESUMO

A metabolic imbalance between lipid synthesis and degradation can lead to hepatic lipid accumulation, a characteristic of patients with non-alcoholic fatty liver disease (NAFLD). Here, we report that high-fat-diet-induced sterol regulatory element-binding protein (SREBP)-1c, a key transcription factor that regulates lipid biosynthesis, impairs autophagic lipid catabolism via altered H2S signaling. SREBP-1c reduced cystathionine gamma-lyase (CSE) via miR-216a, which in turn decreased hepatic H2S levels and sulfhydration-dependent activation of Unc-51-like autophagy-activating kinase 1 (ULK1). Furthermore, Cys951Ser mutation of ULK1 decreased autolysosome formation and promoted hepatic lipid accumulation in mice, suggesting that the loss of ULK1 sulfhydration was directly associated with the pathogenesis of NAFLD. Moreover, silencing of CSE in SREBP-1c knockout mice increased liver triglycerides, confirming the connection between CSE, autophagy, and SREBP-1c. Overall, our results uncover a 2-fold mechanism for SREBP-1c-driven hepatic lipid accumulation through reciprocal activation and inhibition of hepatic lipid biosynthesis and degradation, respectively.


Assuntos
Proteína Homóloga à Proteína-1 Relacionada à Autofagia/metabolismo , Fígado Gorduroso/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Animais , Autofagia , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/genética , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/fisiologia , Linhagem Celular Tumoral , Dieta Hiperlipídica/efeitos adversos , Fígado Gorduroso/fisiopatologia , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Metabolismo dos Lipídeos/fisiologia , Lipídeos/fisiologia , Lipogênese , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Hepatopatia Gordurosa não Alcoólica/metabolismo , Transdução de Sinais/fisiologia , Proteína de Ligação a Elemento Regulador de Esterol 1/genética , Proteína de Ligação a Elemento Regulador de Esterol 1/fisiologia , Triglicerídeos/metabolismo
6.
Nature ; 604(7904): 134-140, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35130559

RESUMO

The SARS-CoV-2 virus has infected more than 261 million people and has led to more than 5 million deaths in the past year and a half1 ( https://www.who.org/ ). Individuals with SARS-CoV-2 infection typically develop mild-to-severe flu-like symptoms, whereas infection of a subset of individuals leads to severe-to-fatal clinical outcomes2. Although vaccines have been rapidly developed to combat SARS-CoV-2, there has been a dearth of antiviral therapeutics. There is an urgent need for therapeutics, which has been amplified by the emerging threats of variants that may evade vaccines. Large-scale efforts are underway to identify antiviral drugs. Here we screened approximately 18,000 drugs for antiviral activity using live virus infection in human respiratory cells and validated 122 drugs with antiviral activity and selectivity against SARS-CoV-2. Among these candidates are 16 nucleoside analogues, the largest category of clinically used antivirals. This included the antivirals remdesivir and molnupiravir, which have been approved for use in COVID-19. RNA viruses rely on a high supply of nucleoside triphosphates from the host to efficiently replicate, and we identified a panel of host nucleoside biosynthesis inhibitors as antiviral. Moreover, we found that combining pyrimidine biosynthesis inhibitors with antiviral nucleoside analogues synergistically inhibits SARS-CoV-2 infection in vitro and in vivo against emerging strains of SARS-CoV-2, suggesting a clinical path forward.


Assuntos
Antivirais , Avaliação Pré-Clínica de Medicamentos , Nucleosídeos , Pirimidinas , SARS-CoV-2 , Monofosfato de Adenosina/análogos & derivados , Alanina/análogos & derivados , Antivirais/farmacologia , COVID-19/virologia , Linhagem Celular , Citidina/análogos & derivados , Humanos , Hidroxilaminas , Nucleosídeos/análogos & derivados , Nucleosídeos/farmacologia , Pirimidinas/farmacologia , SARS-CoV-2/efeitos dos fármacos , Tratamento Farmacológico da COVID-19
7.
EMBO J ; 42(19): e113481, 2023 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-37575012

RESUMO

The NLRP3 inflammasome plays a key role in responding to pathogens, and endogenous damage and mitochondria are intensively involved in inflammasome activation. The NLRP3 inflammasome forms multiprotein complexes and its sequential assembly is important for its activation. Here, we show that NLRP3 is ubiquitinated by the mitochondria-associated E3 ligase, MARCH5. Myeloid cell-specific March5 conditional knockout (March5 cKO) mice failed to secrete IL-1ß and IL-18 and exhibited an attenuated mortality rate upon LPS or Pseudomonas aeruginosa challenge. Macrophages derived from March5 cKO mice also did not produce IL-1ß and IL-18 after microbial infection. Mechanistically, MARCH5 interacts with the NACHT domain of NLRP3 and promotes K27-linked polyubiquitination on K324 and K430 residues of NLRP3. Ubiquitination-defective NLRP3 mutants on K324 and K430 residues are not able to bind to NEK7, nor form NLRP3 oligomers leading to abortive ASC speck formation and diminished IL-1ß production. Thus, MARCH5-dependent NLRP3 ubiquitination on the mitochondria is required for NLRP3-NEK7 complex formation and NLRP3 oligomerization. We propose that the E3 ligase MARCH5 is a regulator of NLRP3 inflammasome activation on the mitochondria.


Assuntos
Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Animais , Camundongos , Inflamassomos/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Interleucina-18/metabolismo , Ubiquitinação , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Caspase 1/metabolismo
8.
N Engl J Med ; 391(8): 710-721, 2024 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-39167807

RESUMO

BACKGROUND: Belzutifan, a hypoxia-inducible factor 2α inhibitor, showed clinical activity in clear-cell renal-cell carcinoma in early-phase studies. METHODS: In a phase 3, multicenter, open-label, active-controlled trial, we enrolled participants with advanced clear-cell renal-cell carcinoma who had previously received immune checkpoint and antiangiogenic therapies and randomly assigned them, in a 1:1 ratio, to receive 120 mg of belzutifan or 10 mg of everolimus orally once daily until disease progression or unacceptable toxic effects occurred. The dual primary end points were progression-free survival and overall survival. The key secondary end point was the occurrence of an objective response (a confirmed complete or partial response). RESULTS: A total of 374 participants were assigned to belzutifan, and 372 to everolimus. At the first interim analysis (median follow-up, 18.4 months), the median progression-free survival was 5.6 months in both groups; at 18 months, 24.0% of the participants in the belzutifan group and 8.3% in the everolimus group were alive and free of progression (two-sided P = 0.002, which met the prespecified significance criterion). A confirmed objective response occurred in 21.9% of the participants (95% confidence interval [CI], 17.8 to 26.5) in the belzutifan group and in 3.5% (95% CI, 1.9 to 5.9) in the everolimus group (P<0.001, which met the prespecified significance criterion). At the second interim analysis (median follow-up, 25.7 months), the median overall survival was 21.4 months in the belzutifan group and 18.1 months in the everolimus group; at 18 months, 55.2% and 50.6% of the participants, respectively, were alive (hazard ratio for death, 0.88; 95% CI, 0.73 to 1.07; two-sided P = 0.20, which did not meet the prespecified significance criterion). Grade 3 or higher adverse events of any cause occurred in 61.8% of the participants in the belzutifan group (grade 5 in 3.5%) and in 62.5% in the everolimus group (grade 5 in 5.3%). Adverse events led to discontinuation of treatment in 5.9% and 14.7% of the participants, respectively. CONCLUSIONS: Belzutifan showed a significant benefit over everolimus with respect to progression-free survival and objective response in participants with advanced clear-cell renal-cell carcinoma who had previously received immune checkpoint and antiangiogenic therapies. Belzutifan was associated with no new safety signals. (Funded by Merck Sharp and Dohme, a subsidiary of Merck; LITESPARK-005 ClinicalTrials.gov number, NCT04195750.).


Assuntos
Antineoplásicos , Carcinoma de Células Renais , Everolimo , Indenos , Neoplasias Renais , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Antineoplásicos/uso terapêutico , Antineoplásicos/efeitos adversos , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/mortalidade , Everolimo/administração & dosagem , Everolimo/efeitos adversos , Estimativa de Kaplan-Meier , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/mortalidade , Intervalo Livre de Progressão , Indenos/administração & dosagem , Indenos/efeitos adversos , Administração Oral , Fatores de Transcrição Hélice-Alça-Hélice Básicos/antagonistas & inibidores , Adulto Jovem , Resultado do Tratamento
9.
N Engl J Med ; 390(15): 1359-1371, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38631003

RESUMO

BACKGROUND: Adjuvant pembrolizumab therapy after surgery for renal-cell carcinoma was approved on the basis of a significant improvement in disease-free survival in the KEYNOTE-564 trial. Whether the results regarding overall survival from the third prespecified interim analysis of the trial would also favor pembrolizumab was uncertain. METHODS: In this phase 3, double-blind, placebo-controlled trial, we randomly assigned (in a 1:1 ratio) participants with clear-cell renal-cell carcinoma who had an increased risk of recurrence after surgery to receive pembrolizumab (at a dose of 200 mg) or placebo every 3 weeks for up to 17 cycles (approximately 1 year) or until recurrence, the occurrence of unacceptable toxic effects, or withdrawal of consent. A significant improvement in disease-free survival according to investigator assessment (the primary end point) was shown previously. Overall survival was the key secondary end point. Safety was a secondary end point. RESULTS: A total of 496 participants were assigned to receive pembrolizumab and 498 to receive placebo. As of September 15, 2023, the median follow-up was 57.2 months. The disease-free survival benefit was consistent with that in previous analyses (hazard ratio for recurrence or death, 0.72; 95% confidence interval [CI], 0.59 to 0.87). A significant improvement in overall survival was observed with pembrolizumab as compared with placebo (hazard ratio for death, 0.62; 95% CI, 0.44 to 0.87; P = 0.005). The estimated overall survival at 48 months was 91.2% in the pembrolizumab group, as compared with 86.0% in the placebo group; the benefit was consistent across key subgroups. Pembrolizumab was associated with a higher incidence of serious adverse events of any cause (20.7%, vs. 11.5% with placebo) and of grade 3 or 4 adverse events related to pembrolizumab or placebo (18.6% vs. 1.2%). No deaths were attributed to pembrolizumab therapy. CONCLUSIONS: Adjuvant pembrolizumab was associated with a significant and clinically meaningful improvement in overall survival, as compared with placebo, among participants with clear-cell renal-cell carcinoma at increased risk for recurrence after surgery. (Funded by Merck Sharp and Dohme, a subsidiary of Merck; KEYNOTE-564 ClinicalTrials.gov number, NCT03142334.).


Assuntos
Antineoplásicos Imunológicos , Carcinoma de Células Renais , Neoplasias Renais , Humanos , Adjuvantes Imunológicos/administração & dosagem , Adjuvantes Imunológicos/efeitos adversos , Adjuvantes Imunológicos/uso terapêutico , Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais Humanizados/efeitos adversos , Anticorpos Monoclonais Humanizados/uso terapêutico , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/mortalidade , Carcinoma de Células Renais/cirurgia , Método Duplo-Cego , Neoplasias Renais/tratamento farmacológico , Neoplasias Renais/mortalidade , Neoplasias Renais/cirurgia , Antineoplásicos Imunológicos/administração & dosagem , Antineoplásicos Imunológicos/efeitos adversos , Antineoplásicos Imunológicos/uso terapêutico , Intervalo Livre de Doença , Terapia Combinada , Análise de Sobrevida
10.
Proc Natl Acad Sci U S A ; 121(25): e2310433121, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38857402

RESUMO

Pleasure and pain are two fundamental, intertwined aspects of human emotions. Pleasurable sensations can reduce subjective feelings of pain and vice versa, and we often perceive the termination of pain as pleasant and the absence of pleasure as unpleasant. This implies the existence of brain systems that integrate them into modality-general representations of affective experiences. Here, we examined representations of affective valence and intensity in an functional MRI (fMRI) study (n = 58) of sustained pleasure and pain. We found that the distinct subpopulations of voxels within the ventromedial and lateral prefrontal cortices, the orbitofrontal cortex, the anterior insula, and the amygdala were involved in decoding affective valence versus intensity. Affective valence and intensity predictive models showed significant decoding performance in an independent test dataset (n = 62). These models were differentially connected to distinct large-scale brain networks-the intensity model to the ventral attention network and the valence model to the limbic and default mode networks. Overall, this study identified the brain representations of affective valence and intensity across pleasure and pain, promoting a systems-level understanding of human affective experiences.


Assuntos
Encéfalo , Imageamento por Ressonância Magnética , Dor , Prazer , Humanos , Prazer/fisiologia , Masculino , Feminino , Dor/fisiopatologia , Dor/psicologia , Adulto , Encéfalo/fisiologia , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Adulto Jovem , Tonsila do Cerebelo/fisiologia , Tonsila do Cerebelo/diagnóstico por imagem , Emoções/fisiologia , Córtex Pré-Frontal/fisiologia , Córtex Pré-Frontal/diagnóstico por imagem , Afeto/fisiologia
11.
Proc Natl Acad Sci U S A ; 121(14): e2400868121, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38547066

RESUMO

Partial cystectomy procedures for urinary bladder-related dysfunction involve long recovery periods, during which urodynamic studies (UDS) intermittently assess lower urinary tract function. However, UDS are not patient-friendly, they exhibit user-to-user variability, and they amount to snapshots in time, limiting the ability to collect continuous, longitudinal data. These procedures also pose the risk of catheter-associated urinary tract infections, which can progress to ascending pyelonephritis due to prolonged lower tract manipulation in high-risk patients. Here, we introduce a fully bladder-implantable platform that allows for continuous, real-time measurements of changes in mechanical strain associated with bladder filling and emptying via wireless telemetry, including a wireless bioresorbable strain gauge validated in a benchtop partial cystectomy model. We demonstrate that this system can reproducibly measure real-time changes in a rodent model up to 30 d postimplantation with minimal foreign body response. Studies in a nonhuman primate partial cystectomy model demonstrate concordance of pressure measurements up to 8 wk compared with traditional UDS. These results suggest that our system can be used as a suitable alternative to UDS for long-term postoperative bladder recovery monitoring.


Assuntos
Bexiga Urinária , Infecções Urinárias , Animais , Humanos , Bexiga Urinária/cirurgia , Urodinâmica/fisiologia , Próteses e Implantes , Cistectomia
12.
Nature ; 583(7818): 785-789, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32690938

RESUMO

An exciton is the bosonic quasiparticle of electron-hole pairs bound by the Coulomb interaction1. Bose-Einstein condensation of this exciton state has long been the subject of speculation in various model systems2,3, and examples have been found more recently in optical lattices and two-dimensional materials4-9. Unlike these conventional excitons formed from extended Bloch states4-9, excitonic bound states from intrinsically many-body localized states are rare. Here we show that a spin-orbit-entangled exciton state appears below the Néel temperature of 150 kelvin in NiPS3, an antiferromagnetic van der Waals material. It arises intrinsically from the archetypal many-body states of the Zhang-Rice singlet10,11, and reaches a coherent state assisted by the antiferromagnetic order. Using configuration-interaction theory, we determine the origin of the coherent excitonic excitation to be a transition from a Zhang-Rice triplet to a Zhang-Rice singlet. We combine three spectroscopic tools-resonant inelastic X-ray scattering, photoluminescence and optical absorption-to characterize the exciton and to demonstrate an extremely narrow excitonic linewidth below 50 kelvin. The discovery of the spin-orbit-entangled exciton in antiferromagnetic NiPS3 introduces van der Waals magnets as a platform to study coherent many-body excitons.

13.
Nature ; 582(7813): 520-524, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32581378

RESUMO

Fundamental studies of chemical reactions often consider the molecular dynamics along a reaction coordinate using a calculated or suggested potential energy surface1-5. But fully mapping such dynamics experimentally, by following all nuclear motions in a time-resolved manner-that is, the motions of wavepackets-is challenging and has not yet been realized even for the simple stereotypical bimolecular reaction6-8: A-B + C â†’ A + B-C. Here we track the trajectories of these vibrational wavepackets during photoinduced bond formation of the gold trimer complex [Au(CN)2-]3 in an aqueous monomer solution, using femtosecond X-ray liquidography9-12 with X-ray free-electron lasers13,14. In the complex, which forms when three monomers A, B and C cluster together through non-covalent interactions15,16, the distance between A and B is shorter than that between B and C. Tracking the wavepacket in three-dimensional nuclear coordinates reveals that within the first 60 femtoseconds after photoexcitation, a covalent bond forms between A and B to give A-B + C. The second covalent bond, between B and C, subsequently forms within 360 femtoseconds to give a linear and covalently bonded trimer complex A-B-C. The trimer exhibits harmonic vibrations that we map and unambiguously assign to specific normal modes using only the experimental data. In principle, more intense X-rays could visualize the motion not only of highly scattering atoms such as gold but also of lighter atoms such as carbon and nitrogen, which will open the door to the direct tracking of the atomic motions involved in many chemical reactions.

14.
Nucleic Acids Res ; 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39217466

RESUMO

PARP inhibitors (PARPi) show selective efficacy in tumors with homologous recombination repair (HRR)-defects but the activation mechanism of HRR pathway in PARPi-treated cells remains enigmatic. To unveil it, we searched for the mediator bridging PARP1 to ATM pathways by screening 211 human ubiquitin-related proteins. We discovered TRIM44 as a crucial mediator that recruits the MRN complex to damaged chromatin, independent of PARP1 activity. TRIM44 binds PARP1 and regulates the ubiquitination-PARylation balance of PARP1, which facilitates timely recruitment of the MRN complex for DSB repair. Upon exposure to PARPi, TRIM44 shifts its binding from PARP1 to the MRN complex via its ZnF UBP domain. Knockdown of TRIM44 in cells significantly enhances the sensitivity to olaparib and overcomes the resistance to olaparib induced by 53BP1 deficiency. These observations emphasize the central role of TRIM44 in tethering PARP1 to the ATM-mediated repair pathway. Suppression of TRIM44 may enhance PARPi effectiveness and broaden their use even to HR-proficient tumors.

15.
Proc Natl Acad Sci U S A ; 120(14): e2221438120, 2023 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-36972448

RESUMO

Converting anthropogenic CO2 to value-added products using renewable energy has received much attention to achieve a sustainable carbon cycle. CO2 electrolysis has been extensively investigated, but the products have been limited to some C1-3 products. Here, we report the integration of CO2 electrolysis with microbial fermentation to directly produce poly-3-hydroxybutyrate (PHB), a microbial polyester, from gaseous CO2 on a gram scale. This biohybrid system comprises electrochemical conversion of CO2 to formate on Sn catalysts deposited on a gas diffusion electrode (GDE) and subsequent conversion of formate to PHB by Cupriavidus necator cells in a fermenter. The electrolyzer and the electrolyte solution were optimized for this biohybrid system. In particular, the electrolyte solution containing formate was continuously circulated through both the CO2 electrolyzer and the fermenter, resulting in the efficient accumulation of PHB in C. necator cells, reaching a PHB content of 83% of dry cell weight and producing 1.38 g PHB using 4 cm2 Sn GDE. This biohybrid system was further modified to enable continuous PHB production operated at a steady state by adding fresh cells and removing PHB. The strategies employed for developing this biohybrid system will be useful for establishing other biohybrid systems producing chemicals and materials directly from gaseous CO2.

16.
Proc Natl Acad Sci U S A ; 120(30): e2219972120, 2023 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-37463206

RESUMO

Current theory for surface tension-dominant jumps on water, created for small- and medium-sized water strider species and used in bioinspired engineering, predicts that jumping individuals are able to match their downward leg movement speed to their size and morphology such that they maximize the takeoff speed and minimize the takeoff delay without breaking the water surface. Here, we use empirical observations and theoretical modeling to show that large species (heavier than ~80 mg) could theoretically perform the surface-dominated jumps according to the existing model, but they do not conform to its predictions, and switch to using surface-breaking jumps in order to achieve jumping performance sufficient for evading attacks from underwater predators. This illustrates how natural selection for avoiding predators may break the theoretical scaling relationship between prey size and its jumping performance within one physical mechanism, leading to an evolutionary shift to another mechanism that provides protection from attacking predators. Hence, the results are consistent with a general idea: Natural selection for the maintenance of adaptive function of a specific behavior performed within environmental physical constraints leads to size-specific shift to behaviors that use a new physical mechanism that secure the adaptive function.


Assuntos
Movimento , Água , Humanos , Tamanho Corporal , Tensão Superficial , Fenômenos Biomecânicos , Locomoção
17.
Proc Natl Acad Sci U S A ; 120(12): e2220649120, 2023 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-36920925

RESUMO

Subthreshold depolarization enhances neurotransmitter release evoked by action potentials and plays a key role in modulating synaptic transmission by combining analog and digital signals. This process is known to be Ca2+ dependent. However, the underlying mechanism of how small changes in basal Ca2+ caused by subthreshold depolarization can regulate transmitter release triggered by a large increase in local Ca2+ is not well understood. This study aimed to investigate the source and signaling mechanisms of Ca2+ that couple subthreshold depolarization with the enhancement of glutamate release in hippocampal cultures and CA3 pyramidal neurons. Subthreshold depolarization increased presynaptic Ca2+ levels, the frequency of spontaneous release, and the amplitude of evoked release, all of which were abolished by blocking L-type Ca2+ channels. A high concentration of intracellular Ca2+ buffer or blockade of calmodulin abolished depolarization-induced increases in transmitter release. Estimation of the readily releasable pool size using hypertonic sucrose showed depolarization-induced increases in readily releasable pool size, and this increase was abolished by the blockade of calmodulin. Our results provide mechanistic insights into the modulation of transmitter release by subthreshold potential change and highlight the role of L-type Ca2+ channels in coupling subthreshold depolarization to the activation of Ca2+-dependent signaling molecules that regulate transmitter release.


Assuntos
Canais de Cálcio Tipo L , Cálcio , Potenciais Evocados , Ácido Glutâmico , Potenciais da Membrana , Canais de Cálcio Tipo L/metabolismo , Ácido Glutâmico/metabolismo , Calmodulina/metabolismo , Cálcio/metabolismo , Terminações Pré-Sinápticas/metabolismo , Neurotransmissores/metabolismo , Animais , Ratos , Células Cultivadas , Hipocampo/citologia , Neurônios/metabolismo , Ratos Sprague-Dawley , Transmissão Sináptica
18.
Nat Mater ; 23(7): 984-992, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38486095

RESUMO

Unlike proteins, which have a wealth of validated structural data, experimentally or computationally validated DNA origami datasets are limited. Here we present a graph neural network that can predict the three-dimensional conformation of DNA origami assemblies both rapidly and accurately. We develop a hybrid data-driven and physics-informed approach for model training, designed to minimize not only the data-driven loss but also the physics-informed loss. By employing an ensemble strategy, the model can successfully infer the shape of monomeric DNA origami structures almost in real time. Further refinement of the model in an unsupervised manner enables the analysis of supramolecular assemblies consisting of tens to hundreds of DNA blocks. The proposed model enables an automated inverse design of DNA origami structures for given target shapes. Our approach facilitates the real-time virtual prototyping of DNA origami, broadening its design space.


Assuntos
DNA , Redes Neurais de Computação , Conformação de Ácido Nucleico , DNA/química
19.
Nat Mater ; 23(2): 290-300, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37845321

RESUMO

Measuring cellular and tissue mechanics inside intact living organisms is essential for interrogating the roles of force in physiological and disease processes. Current agents for studying the mechanobiology of intact, living organisms are limited by poor light penetration and material stability. Magnetomotive ultrasound is an emerging modality for real-time in vivo imaging of tissue mechanics. Nonetheless, it has poor sensitivity and spatiotemporal resolution. Here we describe magneto-gas vesicles (MGVs), protein nanostructures based on gas vesicles and magnetic nanoparticles that produce differential ultrasound signals in response to varying mechanical properties of surrounding tissues. These hybrid nanomaterials significantly improve signal strength and detection sensitivity. Furthermore, MGVs enable non-invasive, long-term and quantitative measurements of mechanical properties within three-dimensional tissues and in vivo fibrosis models. Using MGVs as novel contrast agents, we demonstrate their potential for non-invasive imaging of tissue elasticity, offering insights into mechanobiology and its application to disease diagnosis and treatment.


Assuntos
Nanopartículas , Nanoestruturas , Diagnóstico por Imagem/métodos , Proteínas/química , Acústica , Nanopartículas/química
20.
Nat Mater ; 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39198713

RESUMO

Novel two-dimensional semiconductor crystals can exhibit diverse physical properties beyond their inherent semiconducting attributes, making their pursuit paramount. Memristive properties, as exemplars of these attributes, are predominantly manifested in wide-bandgap materials. However, simultaneously harnessing semiconductor properties alongside memristive characteristics to produce memtransistors is challenging. Herein we prepared a class of semiconducting III-V-derived van der Waals crystals, specifically the HxA1-xBX form, exhibiting memristive characteristics. To identify candidates for the material synthesis, we conducted a systematic high-throughput screening, leading us to 44 prospective III-V candidates; of these, we successfully synthesized ten, including nitrides, phosphides, arsenides and antimonides. These materials exhibited intriguing characteristics such as electrochemical polarization and memristive phenomena while retaining their semiconductive attributes. We demonstrated the gate-tunable synaptic and logic functions within single-gate memtransistors, capitalizing on the synergistic interplay between the semiconducting and memristive properties of our two-dimensional crystals. Our approach guides the discovery of van der Waals materials with unique properties from unconventional crystal symmetries.

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