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The intricate network of the brain's neurons and synapses poses unparalleled challenges for research, distinct from other biological studies. This is particularly true when dissecting how neurons and their functional units work at a cell biological level. While traditional microscopy has been foundational, it was unable to reveal the deeper complexities of neural interactions. However, an imaging renaissance has transformed our capabilities. Advancements in light and electron microscopy, combined with correlative imaging, now achieve unprecedented resolutions, uncovering the most nuanced neural structures. Maximizing these tools requires more than just technical proficiency. It is crucial to align research aims, allocate resources wisely, and analyze data effectively. At the heart of this evolution is interdisciplinary collaboration, where various experts come together to translate detailed imagery into significant biological insights. This review navigates the latest developments in microscopy, underscoring both the promise of and prerequisites for bending this powerful tool set to understanding neuronal cell biology.
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Microscopia , Neurônios , Neurônios/fisiologia , Animais , Humanos , Microscopia/métodos , Biologia Celular , Encéfalo/fisiologia , Sinapses/fisiologiaRESUMO
Alzheimer's disease has a higher incidence in older women, with a spike in cognitive decline that tracks with visceral adiposity, dysregulated energy homeostasis and bone loss during the menopausal transition1,2. Inhibiting the action of follicle-stimulating hormone (FSH) reduces body fat, enhances thermogenesis, increases bone mass and lowers serum cholesterol in mice3-7. Here we show that FSH acts directly on hippocampal and cortical neurons to accelerate amyloid-ß and Tau deposition and impair cognition in mice displaying features of Alzheimer's disease. Blocking FSH action in these mice abrogates the Alzheimer's disease-like phenotype by inhibiting the neuronal C/EBPß-δ-secretase pathway. These data not only suggest a causal role for rising serum FSH levels in the exaggerated Alzheimer's disease pathophysiology during menopause, but also reveal an opportunity for treating Alzheimer's disease, obesity, osteoporosis and dyslipidaemia with a single FSH-blocking agent.
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Doença de Alzheimer , Hormônio Foliculoestimulante , Idoso , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Animais , Densidade Óssea , Cognição , Feminino , Hormônio Foliculoestimulante/metabolismo , Humanos , Camundongos , TermogêneseRESUMO
RIP1 and RIP3 kinases are central players in TNF-induced programmed necrosis. Here, we report that the RIP homotypic interaction motifs (RHIMs) of RIP1 and RIP3 mediate the assembly of heterodimeric filamentous structures. The fibrils exhibit classical characteristics of ß-amyloids, as shown by Thioflavin T (ThT) and Congo red (CR) binding, circular dichroism, infrared spectroscopy, X-ray diffraction, and solid-state NMR. Structured amyloid cores are mapped in RIP1 and RIP3 that are flanked by regions of mobility. The endogenous RIP1/RIP3 complex isolated from necrotic cells binds ThT, is ultrastable, and has a fibrillar core structure, whereas necrosis is partially inhibited by ThT, CR, and another amyloid dye, HBX. Mutations in the RHIMs of RIP1 and RIP3 that are defective in the interaction compromise cluster formation, kinase activation, and programmed necrosis in vivo. The current study provides insight into the structural changes that occur when RIP kinases are triggered to execute different signaling outcomes and expands the realm of amyloids to complex formation and signaling.
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Necrose/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Transdução de Sinais , Sequência de Aminoácidos , Amiloide/química , Humanos , Dados de Sequência Molecular , Domínios e Motivos de Interação entre Proteínas , Proteína Serina-Treonina Quinases de Interação com Receptores/química , Alinhamento de SequênciaRESUMO
Adeno-associated virus (AAV) serotypes from primates are being developed and clinically used as vectors for human gene therapy. However, the evolutionary mechanism of AAV variants is far from being understood, except that genetic recombination plays an important role. Furthermore, little is known about the interaction between AAV and its natural hosts, human and nonhuman primates. In this study, natural AAV capsid genes were subjected to systemic evolutionary analysis with a focus on selection drives during the diversification of AAV lineages. A number of positively selected sites were identified from these AAV lineages with functional relevance implied by their localization on the AAV structures. The selection drives of the two AAV2 capsid sites were further investigated in a series of biological experiments. These observations did not support the evolution of the site 410 of the AAV2 capsid driven by selection pressure from the human CD4+ T-cell response. However, positive selection on site 548 of the AAV2 capsid was directly related to host humoral immunity because of the profound effects of mutations at this site on the immune evasion of AAV variants from human neutralizing antibodies at both the individual and population levels. Overall, this work provides a novel interpretation of the genetic diversity and evolution of AAV lineages in their natural hosts, which may contribute to their further engineering and application in human gene therapy.
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Proteínas do Capsídeo , Dependovirus , Evolução Molecular , Seleção Genética , Dependovirus/genética , Dependovirus/imunologia , Humanos , Animais , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/imunologia , Variação Genética , Terapia GenéticaRESUMO
Working memory (WM) maintenance relies on multiple brain regions and inter-regional communications. The hippocampus and entorhinal cortex (EC) are thought to support this operation. Besides, EC is the main gateway for information between the hippocampus and neocortex. However, the circuit-level mechanism of this interaction during WM maintenance remains unclear in humans. To address these questions, we recorded the intracranial electroencephalography from the hippocampus and EC while patients (N = 13, six females) performed WM tasks. We found that WM maintenance was accompanied by enhanced theta/alpha band (2-12â Hz) phase synchronization between the hippocampus to the EC. The Granger causality and phase slope index analyses consistently showed that WM maintenance was associated with theta/alpha band-coordinated unidirectional influence from the hippocampus to the EC. Besides, this unidirectional inter-regional communication increased with WM load and predicted WM load during memory maintenance. These findings demonstrate that WM maintenance in humans engages the hippocampal-entorhinal circuit, with the hippocampus influencing the EC in a load-dependent manner.
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Hipocampo , Memória de Curto Prazo , Feminino , Humanos , Encéfalo , Eletrocorticografia , Córtex Entorrinal , Eletroencefalografia , Ritmo TetaRESUMO
The volume of ribonucleic acid (RNA)-seq data has increased exponentially, providing numerous new insights into various biological processes. However, due to significant practical challenges, such as data heterogeneity, it is still difficult to ensure the quality of these data when integrated. Although some quality control methods have been developed, sample consistency is rarely considered and these methods are susceptible to artificial factors. Here, we developed MassiveQC, an unsupervised machine learning-based approach, to automatically download and filter large-scale high-throughput data. In addition to the read quality used in other tools, MassiveQC also uses the alignment and expression quality as model features. Meanwhile, it is user-friendly since the cutoff is generated from self-reporting and is applicable to multimodal data. To explore its value, we applied MassiveQC to Drosophila RNA-seq data and generated a comprehensive transcriptome atlas across 28 tissues from embryogenesis to adulthood. We systematically characterized fly gene expression dynamics and found that genes with high expression dynamics were likely to be evolutionarily young and expressed at late developmental stages, exhibiting high nonsynonymous substitution rates and low phenotypic severity, and they were involved in simple regulatory programs. We also discovered that human and Drosophila had strong positive correlations in gene expression in orthologous organs, revealing the great potential of the Drosophila system for studying human development and disease.
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Drosophila melanogaster , Transcriptoma , Humanos , Animais , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Perfilação da Expressão Gênica/métodos , RNA/genética , RNA-Seq , Análise de Sequência de RNA , Sequenciamento de Nucleotídeos em Larga Escala/métodos , DrosophilaRESUMO
Congenital cytomegalovirus (cCMV) is the leading infectious cause of neurologic defects in newborns with particularly severe sequelae in the setting of primary CMV infection in the first trimester of pregnancy. The majority of cCMV cases worldwide occur after non-primary infection in CMV-seropositive women; yet the extent to which pre-existing natural CMV-specific immunity protects against CMV reinfection or reactivation during pregnancy remains ill-defined. We previously reported on a novel nonhuman primate model of cCMV in rhesus macaques where 100% placental transmission and 83% fetal loss were seen in CD4+ T lymphocyte-depleted rhesus CMV (RhCMV)-seronegative dams after primary RhCMV infection. To investigate the protective effect of preconception maternal immunity, we performed reinfection studies in CD4+ T lymphocyte-depleted RhCMV-seropositive dams inoculated in late first / early second trimester gestation with RhCMV strains 180.92 (n = 2), or RhCMV UCD52 and FL-RhCMVΔRh13.1/SIVgag, a wild-type-like RhCMV clone with SIVgag inserted as an immunological marker, administered separately (n = 3). An early transient increase in circulating monocytes followed by boosting of the pre-existing RhCMV-specific CD8+ T lymphocyte and antibody response was observed in the reinfected dams but not in control CD4+ T lymphocyte-depleted dams. Emergence of SIV Gag-specific CD8+ T lymphocyte responses in macaques inoculated with the FL-RhCMVΔRh13.1/SIVgag virus confirmed reinfection. Placental transmission was detected in only one of five reinfected dams and there were no adverse fetal sequelae. Viral whole genome, short-read, deep sequencing analysis confirmed transmission of both reinfection RhCMV strains across the placenta with ~30% corresponding to FL-RhCMVΔRh13.1/SIVgag and ~70% to RhCMV UCD52, consistent with the mixed human CMV infections reported in infants with cCMV. Our data showing reduced placental transmission and absence of fetal loss after non-primary as opposed to primary infection in CD4+ T lymphocyte-depleted dams indicates that preconception maternal CMV-specific CD8+ T lymphocyte and/or humoral immunity can protect against cCMV infection.
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Infecções por Citomegalovirus , Citomegalovirus , Recém-Nascido , Animais , Feminino , Gravidez , Humanos , Citomegalovirus/genética , Macaca mulatta , Reinfecção , Placenta , Imunidade InataRESUMO
In multicellular eukaryotes, autophagy is a conserved process that delivers cellular components to the vacuole or lysosome for recycling during development and stress responses. Induction of autophagy activates AUTOPHAGY-RELATED PROTEIN 1 (ATG1) and ATG13 to form a protein kinase complex that initiates autophagosome formation. However, the detailed molecular mechanism underlying the regulation of this protein complex in plants remains unclear. Here, we determined that in Arabidopsis thaliana, the regulatory proteins 14-3-3λ and 14-3-3κ redundantly modulate autophagy dynamics by facilitating SEVEN IN ABSENTIA OF ARABIDOPSIS THALIANA (SINAT)-mediated proteolysis of ATG13a and ATG13b. 14-3-3λ and 14-3-3κ directly interacted with SINATs and ATG13a/b in vitro and in vivo. Compared to wild-type (WT), the 14-3-3λ 14-3-3κ double mutant showed increased tolerance to nutrient starvation, delayed leaf senescence, and enhanced starvation-induced autophagic vesicles. Moreover, 14-3-3s were required for SINAT1-mediated ubiquitination and degradation of ATG13a. Consistent with their roles in ATG degradation, the 14-3-3λ 14-3-3κ double mutant accumulated higher levels of ATG1a/b/c and ATG13a/b than the WT upon nutrient deprivation. Furthermore, the specific association of 14-3-3s with phosphorylated ATG13a was crucial for ATG13a stability and formation of the ATG1-ATG13 complex. Thus, our findings demonstrate that 14-3-3λ and 14-3-3κ function as molecular adaptors to regulate autophagy by modulating the homeostasis of phosphorylated ATG13.
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Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas 14-3-3/genética , Proteínas 14-3-3/metabolismo , Autofagia/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas Relacionadas à Autofagia/genética , Proteínas Relacionadas à Autofagia/metabolismo , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
The sequence space accessible to evolving proteins can be enhanced by cellular chaperones that assist biophysically defective clients in navigating complex folding landscapes. It is also possible, at least in theory, for proteostasis mechanisms that promote strict quality control to greatly constrain accessible protein sequence space. Unfortunately, most efforts to understand how proteostasis mechanisms influence evolution rely on artificial inhibition or genetic knockdown of specific chaperones. The few experiments that perturb quality control pathways also generally modulate the levels of only individual quality control factors. Here, we use chemical genetic strategies to tune proteostasis networks via natural stress response pathways that regulate the levels of entire suites of chaperones and quality control mechanisms. Specifically, we upregulate the unfolded protein response (UPR) to test the hypothesis that the host endoplasmic reticulum (ER) proteostasis network shapes the sequence space accessible to human immunodeficiency virus-1 (HIV-1) envelope (Env) protein. Elucidating factors that enhance or constrain Env sequence space is critical because Env evolves extremely rapidly, yielding HIV strains with antibody- and drug-escape mutations. We find that UPR-mediated upregulation of ER proteostasis factors, particularly those controlled by the IRE1-XBP1s UPR arm, globally reduces Env mutational tolerance. Conserved, functionally important Env regions exhibit the largest decreases in mutational tolerance upon XBP1s induction. Our data indicate that this phenomenon likely reflects strict quality control endowed by XBP1s-mediated remodeling of the ER proteostasis environment. Intriguingly, and in contrast, specific regions of Env, including regions targeted by broadly neutralizing antibodies, display enhanced mutational tolerance when XBP1s is induced, hinting at a role for host proteostasis network hijacking in potentiating antibody escape. These observations reveal a key function for proteostasis networks in decreasing instead of expanding the sequence space accessible to client proteins, while also demonstrating that the host ER proteostasis network profoundly shapes the mutational tolerance of Env in ways that could have important consequences for HIV adaptation.
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Infecções por HIV , Proteostase , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático/genética , Infecções por HIV/metabolismo , Humanos , Chaperonas Moleculares/metabolismo , Resposta a Proteínas não DobradasRESUMO
During the COVID-19 pandemic, forecasting COVID-19 trends to support planning and response was a priority for scientists and decision makers alike. In the United States, COVID-19 forecasting was coordinated by a large group of universities, companies, and government entities led by the Centers for Disease Control and Prevention and the US COVID-19 Forecast Hub (https://covid19forecasthub.org). We evaluated approximately 9.7 million forecasts of weekly state-level COVID-19 cases for predictions 1-4 weeks into the future submitted by 24 teams from August 2020 to December 2021. We assessed coverage of central prediction intervals and weighted interval scores (WIS), adjusting for missing forecasts relative to a baseline forecast, and used a Gaussian generalized estimating equation (GEE) model to evaluate differences in skill across epidemic phases that were defined by the effective reproduction number. Overall, we found high variation in skill across individual models, with ensemble-based forecasts outperforming other approaches. Forecast skill relative to the baseline was generally higher for larger jurisdictions (e.g., states compared to counties). Over time, forecasts generally performed worst in periods of rapid changes in reported cases (either in increasing or decreasing epidemic phases) with 95% prediction interval coverage dropping below 50% during the growth phases of the winter 2020, Delta, and Omicron waves. Ideally, case forecasts could serve as a leading indicator of changes in transmission dynamics. However, while most COVID-19 case forecasts outperformed a naïve baseline model, even the most accurate case forecasts were unreliable in key phases. Further research could improve forecasts of leading indicators, like COVID-19 cases, by leveraging additional real-time data, addressing performance across phases, improving the characterization of forecast confidence, and ensuring that forecasts were coherent across spatial scales. In the meantime, it is critical for forecast users to appreciate current limitations and use a broad set of indicators to inform pandemic-related decision making.
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COVID-19 , Previsões , Pandemias , SARS-CoV-2 , COVID-19/epidemiologia , COVID-19/transmissão , Humanos , Previsões/métodos , Estados Unidos/epidemiologia , Pandemias/estatística & dados numéricos , Biologia Computacional , Modelos EstatísticosRESUMO
Sustained attention, as the basis of general cognitive ability, naturally varies across different time scales, spanning from hours, e.g. from wakefulness to drowsiness state, to seconds, e.g. trial-by-trail fluctuation in a task session. Whether there is a unified mechanism underneath such trans-scale variability remains unclear. Here we show that fluctuation of cortical excitation/inhibition (E/I) is a strong modulator to sustained attention in humans across time scales. First, we observed the ability to attend varied across different brain states (wakefulness, postprandial somnolence, sleep deprived), as well as within any single state with larger swings. Second, regardless of the time scale involved, we found highly attentive state was always linked to more balanced cortical E/I characterized by electroencephalography (EEG) features, while deviations from the balanced state led to temporal decline in attention, suggesting the fluctuation of cortical E/I as a common mechanism underneath trans-scale attentional variability. Furthermore, we found the variations of both sustained attention and cortical E/I indices exhibited fractal structure in the temporal domain, exhibiting features of self-similarity. Taken together, these results demonstrate that sustained attention naturally varies across different time scales in a more complex way than previously appreciated, with the cortical E/I as a shared neurophysiological modulator.
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Atenção , Córtex Cerebral , Eletroencefalografia , Vigília , Humanos , Atenção/fisiologia , Masculino , Feminino , Adulto Jovem , Adulto , Vigília/fisiologia , Córtex Cerebral/fisiologia , Inibição Neural/fisiologia , Fatores de Tempo , Excitabilidade Cortical/fisiologia , Privação do Sono/fisiopatologiaRESUMO
Uncovering the neural mechanisms of ostracism experience (including its subclasses of excluded and ignored experiences) is important. However, the resting-state functional brain substrates responsible for individual differences in ostracism experience and its negative effects remain largely undefined. This study explored these issues in a sample of 198 Chinese college students by assessing the amplitude of low-frequency fluctuations and functional connectivity. The findings indicated a positive correlation between ignored experience and the amplitude of low-frequency fluctuations in the right superior frontal gyrus and the functional connectivity between the right superior frontal gyrus and left cerebellum posterior lobe. Additionally, a negative correlation was found between ignored experience and the functional connectivity between the right superior frontal gyrus and the bilateral insula as well as the bilateral inferior parietal lobule. Moreover, the mediation analysis demonstrated that the effects of the functional connectivities of right superior frontal gyrus-left cerebellum posterior lobe and right superior frontal gyrus-right inferior parietal lobule on revenge intention were mediated by ignored experience. Our study offers novel insights into the neural correlates of both individual variations in ignored experience and its typical deleterious effect. These results could deepen our understanding of individual differences in negative experiences and inspire the development of targeted interventions for social stress from the perspective of the brain.
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Individualidade , Imageamento por Ressonância Magnética , Humanos , Imageamento por Ressonância Magnética/métodos , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Lobo Parietal/diagnóstico por imagemRESUMO
Delta-secretase, a lysosomal asparagine endopeptidase (AEP), simultaneously cleaves both APP and tau, controlling the onset of pathogenesis of Alzheimer's disease (AD). However, how this protease is post-translationally regulated remains unclear. Here we report that serine-arginine protein kinase 2 (SRPK2) phosphorylates delta-secretase and enhances its enzymatic activity. SRPK2 phosphorylates serine 226 on delta-secretase and accelerates its autocatalytic cleavage, leading to its cytoplasmic translocation and escalated enzymatic activities. Delta-secretase is highly phosphorylated in human AD brains, tightly correlated with SRPK2 activity. Overexpression of a phosphorylation mimetic (S226D) in young 3xTg mice strongly promotes APP and tau fragmentation and facilitates amyloid plaque deposits and neurofibrillary tangle (NFT) formation, resulting in cognitive impairment. Conversely, viral injection of the non-phosphorylatable mutant (S226A) into 5XFAD mice decreases APP and tau proteolytic cleavage, attenuates AD pathologies, and reverses cognitive defects. Our findings support that delta-secretase phosphorylation by SRPK2 plays a critical role in aggravating AD pathogenesis.
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Doença de Alzheimer/enzimologia , Secretases da Proteína Precursora do Amiloide/metabolismo , Encéfalo/enzimologia , Processamento de Proteína Pós-Traducional , Proteínas Serina-Treonina Quinases/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/fisiopatologia , Doença de Alzheimer/psicologia , Secretases da Proteína Precursora do Amiloide/genética , Animais , Comportamento Animal , Encéfalo/patologia , Encéfalo/fisiopatologia , Cognição , Modelos Animais de Doenças , Predisposição Genética para Doença , Células HEK293 , Células HeLa , Humanos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Emaranhados Neurofibrilares/metabolismo , Emaranhados Neurofibrilares/patologia , Fenótipo , Fosforilação , Placa Amiloide , Proteínas Serina-Treonina Quinases/genética , Transporte Proteico , Interferência de RNA , Serina , Especificidade por Substrato , Fatores de Tempo , Transfecção , Proteínas tau/genética , Proteínas tau/metabolismoRESUMO
Microglia regulate synaptic function in various ways, including the microglial displacement of the surrounding GABAergic synapses, which provides important neuroprotection from certain diseases. However, the physiological role and underlying mechanisms of microglial synaptic displacement remain unclear. In this study, we observed that microglia exhibited heterogeneity during the displacement of GABAergic synapses surrounding neuronal soma in different cortical regions under physiological conditions. Through three-dimensional reconstruction, in vitro co-culture, two-photon calcium imaging, and local field potentials recording, we found that IL-1ß negatively modulated microglial synaptic displacement to coordinate regional heterogeneity in the motor cortex, which impacted the homeostasis of the neural network and improved motor learning ability. We used the Cre-Loxp system and found that IL-1R1 on glutamatergic neurons, rather than that on microglia or GABAergic neurons, mediated the negative effect of IL-1ß on synaptic displacement. This study demonstrates that IL-1ß is critical for the regional heterogeneity of synaptic displacement by coordinating different actions of neurons and microglia via IL-1R1, which impacts both neural network homeostasis and motor learning ability. It provides a theoretical basis for elucidating the physiological role and mechanism of microglial displacement of GABAergic synapses.
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Aprendizagem , Microglia , Cálcio , Neurônios GABAérgicos , Interleucina-1beta , SinapsesRESUMO
Fecundity is arguably one of the most important life history traits, as it is closely tied to fitness. Most arthropods are recognized for their extreme reproductive capacity. For example, a single female of the oriental fruit fly Bactrocera dorsalis, a highly invasive species that is one of the most destructive agricultural pests worldwide, can lay more than 3000 eggs during its life span. The ovary is crucial for insect reproduction and its development requires further investigation at the molecular level. We report here that miR-309a is a regulator of ovarian development in B. dorsalis. Our bioinformatics and molecular studies have revealed that miR-309a binds the transcription factor pannier (GATA-binding factor A/pnr), and this activates yolk vitellogenin 2 (Vg 2) and vitellogenin receptor (VgR) advancing ovarian development. We further show that miR-309a is under the control of juvenile hormone (JH) and independent from 20-hydroxyecdysone. Thus, we identified a JH-controlled miR-309a/pnr axis that regulates Vg2 and VgR to control the ovarian development. This study has further enhanced our understanding of molecular mechanisms governing ovarian development and insect reproduction. It provides a background for identifying targets for controlling important Dipteran pests.
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MicroRNAs , Tephritidae , Animais , Drosophila/metabolismo , Ecdisterona/metabolismo , Feminino , Hormônios Juvenis/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Tephritidae/genética , Tephritidae/metabolismo , Fatores de Transcrição/metabolismo , Vitelogeninas/genética , Vitelogeninas/metabolismoRESUMO
Myofibrils within skeletal muscle are composed of sarcomeres that generate force by contraction when their myosin-rich thick filaments slide past actin-based thin filaments. Although mutations in components of the sarcomere are a major cause of human disease, the highly complex process of sarcomere assembly is not fully understood. Current models of thin filament assembly highlight a central role for filament capping proteins, which can be divided into three protein families, each ascribed with separate roles in thin filament assembly. CapZ proteins have been shown to bind the Z-disc protein α-actinin to form an anchoring complex for thin filaments and actin polymerisation. Subsequent thin filaments extension dynamics are thought to be facilitated by Leiomodins (Lmods) and thin filament assembly is concluded by Tropomodulins (Tmods) that specifically cap the pointed end of thin filaments. To study thin filament assembly in vivo, single and compound loss-of-function zebrafish mutants within distinct classes of capping proteins were analysed. The generated lmod3- and capza1b-deficient zebrafish exhibited aspects of the pathology caused by variations in their human orthologs. Although loss of the analysed main capping proteins of the skeletal muscle, capza1b, capza1a, lmod3 and tmod4, resulted in sarcomere defects, residual organised sarcomeres were formed within the assessed mutants, indicating that these proteins are not essential for the initial myofibril assembly. Furthermore, detected similarity and location of myofibril defects, apparent at the peripheral ends of myofibres of both Lmod3- and CapZα-deficient mutants, suggest a function in longitudinal myofibril growth for both proteins, which is molecularly distinct to the function of Tmod4.
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Proteína de Capeamento de Actina CapZ/metabolismo , Doenças Musculares , Miofibrilas , Actinas/genética , Actinas/metabolismo , Animais , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Doenças Musculares/genética , Doenças Musculares/metabolismo , Miofibrilas/genética , Miofibrilas/metabolismo , Tropomodulina/genética , Tropomodulina/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/metabolismoRESUMO
The ability of molecules to move and rearrange in the solid state accounts for the polymorphic transition and stimuli-responsive properties of molecular crystals. However, how the crystal structure determines the molecular motion ability remains poorly understood. Here, we report that a three-dimensional (3D) supramolecular gear network in the green-emissive polymorph 1G of a dialkylamino-substituted anthracene-pentiptycene π-system (1) enables an unusual bifurcated polymorphic transition into a yellow-emissive polymorph (1Y) and a new green-emissive polymorph (1G*) via 3D correlated supramolecular rotation. The 90° forward correlated rotation causes the molecular conformation between the octyl and the anthracene units to change from syn to anti, the ladder-like supramolecular columns to constrict, and the gear network to disengage. This cooperative molecular motion is marked by the gradual formation of an intermediate state (1I) across the entire crystal from 170 to 230 °C, which then undergoes bifurcated (forward or backward rotation) and irreversible transitions to form polymorphs 1Y and 1G* at 230-235 °C. Notably, 1G* is similar to 1G but lacks gear engagement, preventing its transformation into 1Y. Nevertheless, 1G can be restored by grinding 1Y or 1G* or fuming with dichloromethane (DCM) vapor. This work illustrates the correlation between the crystal structure and solid-state molecular motion behavior and demonstrates how a 3D molecular gear system efficiently transmits thermal energy to drive the polymorphic transition and induce fluorochromism through significant conformational and packing changes.
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Controlling product selectivity in successive reactions of the same type is challenging owing to the comparable thermodynamic and kinetic properties of the reactions involved. Here, the synergistic interaction of the two phosphoryl groups in bisphosphine dioxides (BPDOs) with a bromo-phosphonium cation was studied experimentally to provide a practical tool for substrate-catalyst recognition. As the eventual result, we have developed a phosphonium-catalyzed monoreduction of chiral BPDOs to access an array of synthetically useful bisphosphine monoxides (BPMOs) with axial, spiro, and planar chirality, which are otherwise challenging to synthesize before. The reaction features excellent selectivity and impressive reactivity. It proceeds under mild conditions, avoiding the use of superstoichiometric amounts of additives and metal catalysts to simplify the synthetic procedure. The accessibility and scalability of the reaction allowed for the rapid construction of a ligand library for optimization of asymmetric Heck-type cyclization, laying the foundation for a broad range of applications of chiral BPMOs in catalysis.
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The diversity of leaf characteristics, particularly leaf color, underscores a pivotal area of inquiry within plant science. The synthesis and functionality of chlorophyll, crucial for photosynthesis, largely dictate leaf coloration, with varying concentrations imparting different shades of green. Complex gene interactions regulate the synthesis and degradation of chlorophyll, and disruptions in these pathways can result in abnormal chlorophyll production, thereby affecting leaf pigmentation. This study focuses on Bambusa multiplex f. silverstripe, a natural variant distinguished by a spectrum of leaf colors, such as green, white, and green-white, attributed to genetic variations influencing gene expression. By examining the physiological and molecular mechanisms underlying chlorophyll anomalies and genetic factors in Silverstripe, this research sheds light on the intricate gene interactions and regulatory networks that contribute to leaf color diversity. The investigation includes the measurement of photosynthetic pigments and nutrient concentrations across different leaf color types, alongside transcriptomic analyses for identifying differentially expressed genes. The role of key genes in pathways such as ALA biosynthesis, chlorophyll synthesis, photosynthesis, and sugar metabolism is explored, offering critical insights for advancing research and plant breeding practices.
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BACKGROUND: Liver kinase B1 (LKB1) is frequently mutated in lung adenocarcinoma, and its loss contributes to tumor progression. METHODS: To identify LKB1 downstream genes that promote lung adenocarcinoma aggressiveness, we performed bioinformatical analysis using publicly available datasets. RESULTS: Rab3B was upregulated in LKB1-depleted lung adenocarcinoma cells and suppressed by LKB1 overexpression. CREB protein was enriched at the promoter of Rab3B in lung cancer cells. Silencing of CREB abrogated the upregulation of Rab3B upon LKB1 loss. Immunohistochemistry revealed the elevated expression of Rab3B in lung adenocarcinomas relative to adjacent normal tissues. Upregulation of Rab3B was significantly associated with lymph node metastasis, advanced tumor stage, and reduced overall survival in lung adenocarcinoma patients. Knockdown of Rab3B suppressed and overexpression of Rab3B promoted the proliferation, colony formation, and migration of lung adenocarcinoma cells in vitro. In a mouse xenograft model, Rab3B depletion restrained and Rab3B overexpression augmented the growth of lung adenocarcinoma tumors. Mechanistically, Rab3B interacted with DDX6 and enhanced its protein stability. Ectopic expression of DDX6 significantly promoted the proliferation, colony formation, and migration of lung adenocarcinoma cells. DDX6 knockdown phenocopied the effects of Rab3B depletion on lung adenocarcinoma cells. Additionally, DDX6 overexpression partially rescued the aggressive phenotype of Rab3B-depleted lung adenocarcinoma cells. CONCLUSION: LKB1 deficiency promotes Rab3B upregulation via a CREB-dependent manner. Rab3B interacts with and stabilizes DDX6 protein to accelerate lung adenocarcinoma progression. The Rab3B-DDX6 axis may be potential therapeutic target for lung adenocarcinoma.