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Under defined differentiation conditions, human embryonic stem cells (hESCs) can be directed toward a mesendoderm (ME) or neuroectoderm (NE) fate, the first decision during hESC differentiation. Coupled with lineage-specific G1 lengthening, a divergent ciliation pattern emerged within the first 24 hr of induced lineage specification, and these changes heralded a neuroectoderm decision before any neural precursor markers were expressed. By day 2, increased ciliation in NE precursors induced autophagy that resulted in the inactivation of Nrf2 and thereby relieved transcriptional activation of OCT4 and NANOG. Nrf2 binds directly to upstream regions of these pluripotency genes to promote their expression and repress NE derivation. Nrf2 suppression was sufficient to rescue poorly neurogenic iPSC lines. Only after these events had been initiated did neural precursor markers get expressed at day 4. Thus, we have identified a primary cilium-autophagy-Nrf2 (PAN) control axis coupled to cell-cycle progression that directs hESCs toward NE.
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Autofagia , Cilios/metabolismo , Células Madre Embrionarias/citología , Factor 2 Relacionado con NF-E2/metabolismo , Ciclo Celular , Proteínas de Homeodominio/genética , Humanos , Proteína Homeótica Nanog , Placa Neural/metabolismo , Factor 3 de Transcripción de Unión a Octámeros/genética , Células Madre Pluripotentes/metabolismoRESUMEN
OBJECTIVE: Limited palatal muscle resection (LPMR) is a modified palatal surgical technique to correct retropalatal obstruction without complications. This study aims to determine the associated factors affecting the success and cure rate of LPMR in patients with obstructive sleep apnea (OSA), thus guiding patient selection and improving surgical outcome. METHODS: Thirty-five OSA patients underwent LPMR were enrolled. All patients received routine physical examination, preoperative drug-induced sleep endoscopy (DISE), and polysomnography (PSG). Clinical, polysomnographic, cephalometric variables, and DISE findings were evaluated. These measurements were compared between the surgical success and failure group based on the results of preoperative and postoperative PSG. Furthermore, we compared the cured and non-cured groups in the surgical success group. RESULTS: Among 35 patients, the overall success rate was 57 % with a cure rate of 31.4 %. Patients with Friedman stage II had a significantly higher success rate (p = 0.032). According to DISE results, tongue base obstruction affected the surgical outcome (p < 0.001). The success rate was 100 % in the no tongue base obstruction during DISE, 72.2 % in the partial obstruction, and 9.1 % in the total obstruction. Tonsil size is also helpful in predicting surgical success rate (p = 0.041). Furthermore, patients with mild AHI were more likely to be surgical cures. when compared with patients with severe AHI (p = 0.044). CONCLUSION: Patients with larger tonsil size and no tongue base obstruction during DISE may have a higher chance of surgical success with LPMR. The lower AHI may be predictors of surgical cure after LPMR.
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Músculos Palatinos , Apnea Obstructiva del Sueño , Humanos , Músculos Palatinos/cirugía , Apnea Obstructiva del Sueño/diagnóstico , Apnea Obstructiva del Sueño/cirugía , Hueso Paladar/cirugía , Endoscopía/métodos , Resultado del Tratamiento , SueñoRESUMEN
Gold-catalyzed enantioselective thioallylation of propiolates proved effective in delivering highly enantio-enriched α-allyl-ß-thioacrylates. In this work, we report a revised mechanism for this process based on the new mechanistic experiments and kinetic data in the presence of a competitive inhibitor. The employment of thioethers as nucleophiles inevitably involves their competitive binding to the only catalytic site of the Au(I) catalyst, which may inhibit the activity. We developed a modified Hammett plot in the presence of a dummy thioether inhibitor, which revealed a true kinetic profile, excluding the effect of inhibition. A revised mechanism suggested that the conjugate addition of thioethers to the Au(I)-activated alkynes is the turnover-limiting step, and the subsequent [3,3]-rearrangement occurs quickly, suggesting the efficacy of the sulfonium-based approach in accelerating Claisen rearrangement. In addition, the enantioselectivity was suggested to be determined during the sigmatropic rearrangement by discriminating the prochiral olefin faces of the allyl group in the σ-bound Au(I) complex.
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Ketone bodies (KBs), such as acetoacetate and ß-hydroxybutyrate, serve as crucial alternative energy sources during glucose deficiency. KBs, generated through ketogenesis in the liver, are metabolized into acetyl-CoA in extrahepatic tissues, entering the tricarboxylic acid cycle and electron transport chain for ATP production. Reduced glucose metabolism and mitochondrial dysfunction correlate with increased neuronal death and brain damage during cerebral ischemia and neurodegeneration. Both KBs and the ketogenic diet (KD) demonstrate neuroprotective effects by orchestrating various cellular processes through metabolic and signaling functions. They enhance mitochondrial function, mitigate oxidative stress and apoptosis, and regulate epigenetic and post-translational modifications of histones and non-histone proteins. Additionally, KBs and KD contribute to reducing neuroinflammation and modulating autophagy, neurotransmission systems, and gut microbiome. This review aims to explore the current understanding of the molecular mechanisms underpinning the neuroprotective effects of KBs and KD against brain damage in cerebral ischemia and neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease.
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Lesiones Encefálicas , Dieta Cetogénica , Enfermedades Neurodegenerativas , Fármacos Neuroprotectores , Humanos , Cuerpos Cetónicos , Neuroprotección , Fármacos Neuroprotectores/uso terapéutico , Infarto CerebralRESUMEN
Muscle atrophy, also known as muscle wasting, is the thinning of muscle mass due to muscle disuse, aging, or diseases such as cancer or neurological problems. Muscle atrophy is closely related to the quality of life and has high morbidity and mortality. However, therapeutic options for muscle atrophy are limited, so studies to develop therapeutic agents for muscle loss are always required. For this study, we investigated how orally administered specific collagen peptides (CP) affect muscle atrophy and elucidated its molecular mechanism using an in vivo model. We treated mice with dexamethasone (DEX) to induce a muscular atrophy phenotype and then administered CP (0.25 and 0.5 g/kg) for four weeks. In a microcomputed tomography analysis, CP (0.5 g/kg) intake significantly increased the volume of calf muscles in mice with DEX-induced muscle atrophy. In addition, the administration of CP (0.25 and 0.5 g/kg) restored the weight of the gluteus maximus and the fiber cross-sectional area (CSA) of the pectoralis major and calf muscles, which were reduced by DEX. CP significantly inhibited the mRNA expression of myostatin and the phosphorylation of Smad2, but it did not affect TGF-ß, BDNF, or FNDC5 gene expression. In addition, AKT/mTOR, a central pathway for muscle protein synthesis and related to myostatin signaling, was enhanced in the groups that were administered CP. Finally, CP decreased serum albumin levels and increased TNF-α gene expression. Collectively, our in vivo results demonstrate that CP can alleviate muscle wasting through a multitude of mechanisms. Therefore, we propose CP as a supplement or treatment to prevent muscle atrophy.
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Colágeno , Atrofia Muscular , Miostatina , Animales , Ratones , Dexametasona/efectos adversos , Fibronectinas/metabolismo , Músculo Esquelético/metabolismo , Atrofia Muscular/inducido químicamente , Atrofia Muscular/metabolismo , Microtomografía por Rayos X , Colágeno/farmacologíaRESUMEN
The link between single-cell variation and population-level fate choices lacks a mechanistic explanation despite extensive observations of gene expression and epigenetic variation among individual cells. Here, we found that single human embryonic stem cells (hESCs) have different and biased differentiation potentials toward either neuroectoderm or mesendoderm depending on their G1 lengths before the onset of differentiation. Single-cell variation in G1 length operates in a dynamic equilibrium that establishes a G1 length probability distribution for a population of hESCs and predicts differentiation outcome toward neuroectoderm or mesendoderm lineages. Although sister stem cells generally share G1 lengths, a variable proportion of cells have asymmetric G1 lengths, which maintains the population dispersion. Environmental Wingless-INT (WNT) levels can control the G1 length distribution, apparently as a means of priming the fate of hESC populations once they undergo differentiation. As a downstream mechanism, global 5-hydroxymethylcytosine levels are regulated by G1 length and thereby link G1 length to differentiation outcomes of hESCs. Overall, our findings suggest that intrapopulation heterogeneity in G1 length underlies the pluripotent differentiation potential of stem cell populations.
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Diferenciación Celular , Células Madre Embrionarias/fisiología , Fase G1 , Proteínas Wnt/fisiología , Línea Celular , HumanosRESUMEN
Loratadine is an anti-histamine routinely used for treating allergies. However, recent findings have shown that Loratadine may also have anti-inflammatory functions, while their exact mechanisms have not yet been fully uncovered. In this paper, we investigated whether Loratadine can be utilized as an anti-inflammatory drug through a series of in vitro and in vivo experiments using a murine macrophage cell line and an acute gastritis mouse model. Loratadine was found to dramatically reduce the expression of pro-inflammatory genes, including MMP1, MMP3, and MMP9, and inhibit AP-1 transcriptional activation, as demonstrated by the luciferase assay. Therefore, we decided to further explore its role in the AP-1 signaling pathway. The expression of c-Jun and c-Fos, AP-1 subunits, was repressed by Loratadine and, correspondingly, the expression of p-JNK, p-MKK7, and p-TAK1 was also inhibited. In addition, Loratadine was able to reduce gastric bleeding in acute gastritis-induced mice; Western blotting using the stomach samples showed reduced p-c-Fos protein levels. Loratadine was shown to effectively suppress inflammation by specifically targeting TAK1 and suppressing consequent AP-1 signaling pathway activation and inflammatory cytokine production.
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Gastritis , Factor de Transcripción AP-1 , Animales , Antiinflamatorios/efectos adversos , Gastritis/inducido químicamente , Antagonistas de los Receptores Histamínicos/uso terapéutico , Loratadina/farmacología , Loratadina/uso terapéutico , Ratones , Células RAW 264.7 , Factor de Transcripción AP-1/metabolismoRESUMEN
Compound C (CompC), an inhibitor of AMP-activated protein kinase, reduces the viability of various renal carcinoma cells. The molecular mechanism underlying anti-proliferative effect was investigated by flow cytometry and western blot analysis in Renca cells. Its effect on the growth of Renca xenografts was also examined in a syngeneic BALB/c mouse model. Subsequent results demonstrated that CompC reduced platelet-derived growth factor receptor signaling pathways and increased ERK1/2 activation as well as reactive oxygen species (ROS) production. CompC also increased the level of active Wee1 tyrosine kinase (P-Ser642-Wee1) and the inactive form of Cdk1 (P-Tyr15-Cdk1) while reducing the level of active histone H3 (P-Ser10-H3). ROS-dependent ERK1/2 activation and sequential alterations in Wee1, Cdk1, and histone H3 might be responsible for the CompC-induced G2/M cell cycle arrest and cell viability reduction. In addition, CompC reduced the adhesion, migration, and invasion of Renca cells in the in vitro cell systems, and growth of Renca xenografts in the BALB/c mouse model. Taken together, the inhibition of in vivo tumor growth by CompC may be attributed to the blockage of cell cycle progression, adhesion, migration, and invasion of tumor cells. These findings suggest the therapeutic potential of CompC against tumor development and progression.
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Carcinoma de Células Renales , Neoplasias Renales , Animales , Carcinoma de Células Renales/patología , División Celular , Modelos Animales de Enfermedad , Histonas , Humanos , Neoplasias Renales/metabolismo , Ratones , Ratones Endogámicos BALB C , Especies Reactivas de Oxígeno/metabolismoRESUMEN
A gold(I)-catalyzed enantioselective thioallylation of propiolates with allyl sulfides is described. The key mechanistic element is a sulfonium-induced Claisen rearrangement which helps minimize the allyl dissociation and render higher enantioselectivity. This protocol features remarkable scope of the allyl moiety, allowing enantiocontrolled synthesis of all-carbon quaternary centers, and exhibits exceptional functional group compatibility with many Lewis bases and π-bonds. This intermolecular variant of Claisen rearrangement forges both C-S and C-C bonds concomitantly, providing efficient access to interesting optically active organosulfur compounds which can be transformed further through the vinyl sulfide as a functional handle. The rate of the reaction was zeroth order with respect to allyl sulfides, which suggested a reversible inhibition, providing a resting state for the catalyst. The Hammett plot displayed a correlation with σp values, suggesting a turnover-limiting sigmatropic rearrangement where decreased electron-density on sulfur accelerated the rearrangement.
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Protein arginine methyltransferase 1 (PRMT1) is the most predominant PRMT and is type I, meaning it generates monomethylarginine and asymmetric dimethylarginine. PRMT1 has functions in oxidative stress, inflammation and cancers, and modulates diverse diseases; consequently, numerous trials to develop PRMT1 inhibitors have been attempted. One selective PRMT1 inhibitor is N,N'-(Sulfonyldi-4,1-phenylene)bis(2-chloroacetamide), also named TC-E 5003 (TC-E). In this study, we investigated whether TC-E regulated inflammatory responses. Nitric oxide (NO) production was evaluated by the Griess assay and the inflammatory gene expression was determined by conducting RT-PCR. Western blot analyzing was carried out for inflammatory signaling exploration. TC-E dramatically reduced lipopolysaccharide (LPS)-induced NO production and the expression of inflammatory genes (inducible NO synthase (iNOS), cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α and interleukin (IL)-6) as determined using RT-PCR. TC-E downregulated the nuclear translocation of the nuclear factor (NF)-κB subunits p65 and p50 and the activator protein (AP)-1 transcriptional factor c-Jun. Additionally, TC-E directly regulated c-Jun gene expression following LPS treatment. In NF-κB signaling, the activation of IκBα and Src was attenuated by TC-E. Taken together, these data show that TC-E modulates the lipopolysaccharide (LPS)-induced AP-1 and NF-κB signaling pathways and could possibly be further developed as an anti-inflammatory compound.
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Acetamidas/farmacología , Antiinflamatorios/farmacología , Lipopolisacáridos/efectos adversos , Proteína-Arginina N-Metiltransferasas/antagonistas & inhibidores , Receptor Toll-Like 4/metabolismo , Acetamidas/química , Animales , Antiinflamatorios/química , Línea Celular , Ciclooxigenasa 2/genética , Ciclooxigenasa 2/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Células HEK293 , Humanos , Interleucina-6/genética , Interleucina-6/metabolismo , Ratones , Estructura Molecular , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo II/genética , Óxido Nítrico Sintasa de Tipo II/metabolismo , Estrés Oxidativo/efectos de los fármacos , Células RAW 264.7 , Transducción de Señal/efectos de los fármacos , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
We report the presence of co-occurring extracellular action potentials (eAPs) from cultured mouse hippocampal neurons among groups of planar electrodes on multielectrode arrays (MEAs). The invariant sequences of eAPs among coactive electrode groups, repeated co-occurrences, and short interelectrode latencies are consistent with action potential propagation in unmyelinated axons. Repeated eAP codetection by multiple electrodes was widespread in all our data records. Codetection of eAPs confirms they result from the same neuron and allows these eAPs to be isolated from all other spikes independently of spike sorting algorithms. We averaged co-occurring events and revealed additional electrodes with eAPs that would otherwise be below detection threshold. We used these eAP cohorts to explore the temperature sensitivity of action potential propagation and the relationship between voltage-gated sodium channel density and propagation velocity. The sequence of eAPs among coactive electrodes "fingerprints" neurons giving rise to these events and identifies them within neuronal ensembles. We used this property and the noninvasive nature of extracellular recording to monitor changes in excitability at multiple points in single axonal arbors simultaneously over several hours, demonstrating independence of axonal segments. Over several weeks, we recorded changes in interelectrode propagation latencies and ongoing changes in excitability in different regions of single axonal arbors. Our work illustrates how repeated eAP co-occurrences can be used to extract physiological data from single axons with low-density MEAs. However, repeated eAP co-occurrences lead to oversampling spikes from single neurons and thus can confound traditional spike-train analysis. NEW & NOTEWORTHY We studied action potential propagation in single axons using low-density multielectrode arrays. We unambiguously identified the neuronal sources of propagating action potentials and recorded extracellular action potentials from several positions within single axonal arbors. We found a surprisingly high density of axonal voltage-gated sodium channels responsible for a high propagation safety factor. Our experiments also demonstrate that excitability in different segments of single axons is regulated independently on timescales from hours to weeks.
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Potenciales de Acción , Axones/fisiología , Técnicas de Placa-Clamp/métodos , Análisis de Matrices Tisulares/métodos , Animales , Células Cultivadas , Hipocampo/citología , Masculino , Ratones , Ratones Endogámicos C57BL , Canales de Sodio/metabolismo , TemperaturaRESUMEN
Williams syndrome (WS) is a neurodevelopmental disorder caused by a genomic deletion of â¼28 genes that results in a cognitive and behavioral profile marked by overall intellectual impairment with relative strength in expressive language and hypersocial behavior. Advancements in protocols for neuron differentiation from induced pluripotent stem cells allowed us to elucidate the molecular circuitry underpinning the ontogeny of WS. In patient-derived stem cells and neurons, we determined the expression profile of the Williams-Beuren syndrome critical region-deleted genes and the genome-wide transcriptional consequences of the hemizygous genomic microdeletion at chromosome 7q11.23. Derived neurons displayed disease-relevant hallmarks and indicated novel aberrant pathways in WS neurons including over-activated Wnt signaling accompanying an incomplete neurogenic commitment. We show that haploinsufficiency of the ATP-dependent chromatin remodeler, BAZ1B, which is deleted in WS, significantly contributes to this differentiation defect. Chromatin-immunoprecipitation (ChIP-seq) revealed BAZ1B target gene functions are enriched for neurogenesis, neuron differentiation and disease-relevant phenotypes. BAZ1B haploinsufficiency caused widespread gene expression changes in neural progenitor cells, and together with BAZ1B ChIP-seq target genes, explained 42% of the transcriptional dysregulation in WS neurons. BAZ1B contributes to regulating the balance between neural precursor self-renewal and differentiation and the differentiation defect caused by BAZ1B haploinsufficiency can be rescued by mitigating over-active Wnt signaling in neural stem cells. Altogether, these results reveal a pivotal role for BAZ1B in neurodevelopment and implicate its haploinsufficiency as a likely contributor to the neurological phenotypes in WS.
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Regulación del Desarrollo de la Expresión Génica , Haploinsuficiencia , Células Madre Pluripotentes Inducidas/metabolismo , Neurogénesis , Neuronas/metabolismo , Factores de Transcripción/genética , Síndrome de Williams/metabolismo , Deleción Cromosómica , Cromosomas Humanos Par 7 , Femenino , Humanos , Células Madre Pluripotentes Inducidas/fisiología , Transducción de Señal , Transcripción Genética , Transcriptoma , Síndrome de Williams/genética , Síndrome de Williams/fisiopatologíaRESUMEN
Nuclear factor, erythroid 2-like 2 (Nrf2) is a master transcription factor for cellular defense against endogenous and exogenous stresses by regulating expression of many antioxidant and detoxification genes. Here, we show that Nrf2 acts as a key pluripotency gene and a regulator of proteasome activity in human embryonic stem cells (hESCs). Nrf2 expression is highly enriched in hESCs and dramatically decreases upon differentiation. Nrf2 inhibition impairs both the self-renewal ability of hESCs and re-establishment of pluripotency during cellular reprogramming. Nrf2 activation can delay differentiation. During early hESC differentiation, Nrf2 closely colocalizes with OCT4 and NANOG. As an underlying mechanism, our data show that Nrf2 regulates proteasome activity in hESCs partially through proteasome maturation protein (POMP), a proteasome chaperone, which in turn controls the proliferation of self-renewing hESCs, three germ layer differentiation and cellular reprogramming. Even modest proteasome inhibition skews the balance of early differentiation toward mesendoderm at the expense of an ectodermal fate by decreasing the protein level of cyclin D1 and delaying the degradation of OCT4 and NANOG proteins. Taken together, our findings suggest a new potential link between environmental stress and stemness with Nrf2 and the proteasome coordinately positioned as key mediators.
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Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Factor 2 Relacionado con NF-E2/metabolismo , Células Madre Pluripotentes/citología , Células Madre Pluripotentes/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Ciclo Celular , Proliferación Celular , Reprogramación Celular , Células HEK293 , Humanos , Chaperonas Moleculares/metabolismo , Células Madre Multipotentes/citología , Células Madre Multipotentes/metabolismoRESUMEN
The burgeoning demand for plant-based meat analogs (PBMAs) stems from environmental, health, and ethical concerns, yet replicating the sensory attributes of animal meat remains challenging. This comprehensive review explores recent innovations in PBMA ingredients and methodologies, emphasizing advancements in texture, flavor, and nutritional profiles. It chronicles the transition from soy-based first-generation products to more diversified second- and third-generation PBMAs, showcasing the utilization of various plant proteins and advanced processing techniques to enrich sensory experiences. The review underscores the crucial role of proteins, polysaccharides, and fats in mimicking meat's texture and flavor and emphasizes research on new plant-based sources to improve product quality. Addressing challenges like production costs, taste, texture, and nutritional adequacy is vital for enhancing consumer acceptance and fostering a more sustainable food system.
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An enantioselective Cu(I)-catalyzed coupling of N-carboxyindoles with various 2-naphthols and phenols for the synthesis of axially chiral arylindoles has been developed. Our mechanistic studies, bolstered by experimental evidence and DFT calculations, reveal a novel closed-shell mechanism involving outer-sphere attack of N-carboxyindoles on the Cu-bound naphthols. This mechanism allows for unprecedented diversity of 2-naphthols and phenols in C-H arylation. Enantiocontrol is achieved through center-to-axis chirality transfer via a key dearomatized naphthol intermediate, which prevents undesired epimerization of the C-C axis.
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ETHNOPHARMACOLOGICAL RELEVANCE: Panax ginseng (P. ginseng) C.A. Meyer. Has been studied for decades for its various biological activities, especially in terms of immune-regulatory properties. Traditionally, it has been known that root, leaves, and fruits of P. ginseng were eaten for improving body's Qi and homeostasis. Also, these were used to protect body from various types of infectious diseases. However, molecular mechanisms of immunomodulatory activities of ginseng berries have not been systemically studied as often as other parts of the plant. AIM OF THE STUDY: The aim of this research is to discover the regulatory effects of P. ginseng berries, more importantly, their ginsenosides, on innate immune responses and to elucidate the molecular mechanism. MATERIALS AND METHODS: Ginseng berry concentrate (GBC) was orally injected into BALB/c mice for 30 days, and spleens were extracted for evaluation of immune-regulatory effects. Murine macrophage RAW264.7 cells were used for detailed molecular mechanism studies. Splenic natural killer (NK) cells were isolated using the magnetic-activated cell sorting (MACS) system, and the cytotoxic activity of isolated NK cells was measured using a lactate dehydrogenase (LDH) release assay. The splenic immune cell population was determined by flow-cytometry. NF-κB promoter activity was assessed by in vitro luciferase assay. Expression of inflammatory proteins and cytokines of the spleen and RAW264.7 cells were evaluated using western blotting and real-time PCR, respectively. RESULTS: The GBC enhanced cytotoxic activity of NK cells and the immune-regulation-related splenic cell population. Moreover, GBC promoted NF-κB promoter activity and stimulated the NF-κB signaling cascade. In spleen and RAW264.7 cells, expression of pro-inflammatory cytokines was increased upon GBC application, while expression of anti-inflammatory cytokines decreased. CONCLUSIONS: These results suggest that P. ginseng berry can stimulate innate immune responses and help maintain a balanced immune condition, mostly due to the action of its key ginsenoside Re, along with other protopanaxadiol- and protopanaxatriol-type ginsenosides. Such finding will provide a new insight into the field of well-being diet research as well as non-chemical immune modulator, by providing nature-derived and plant-based bioactive materials.
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Citocinas , Frutas , Ginsenósidos , Células Asesinas Naturales , Macrófagos , Ratones Endogámicos BALB C , FN-kappa B , Panax , Regulación hacia Arriba , Animales , Panax/química , Ginsenósidos/farmacología , FN-kappa B/metabolismo , Ratones , Células RAW 264.7 , Citocinas/metabolismo , Células Asesinas Naturales/efectos de los fármacos , Células Asesinas Naturales/metabolismo , Células Asesinas Naturales/inmunología , Regulación hacia Arriba/efectos de los fármacos , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Macrófagos/inmunología , Transducción de Señal/efectos de los fármacos , Bazo/efectos de los fármacos , Bazo/citología , Bazo/inmunología , Extractos Vegetales/farmacología , MasculinoRESUMEN
Dynamic changes in mechanical microenvironments, such as cell crowding, regulate lineage fates as well as cell proliferation. Although regulatory mechanisms for contact inhibition of proliferation have been extensively studied, it remains unclear how cell crowding induces lineage specification. Here we found that a well-known oncogene, ETS variant transcription factor 4 (ETV4), serves as a molecular transducer that links mechanical microenvironments and gene expression. In a growing epithelium of human embryonic stem cells, cell crowding dynamics is translated into ETV4 expression, serving as a pre-pattern for future lineage fates. A switch-like ETV4 inactivation by cell crowding derepresses the potential for neuroectoderm differentiation in human embryonic stem cell epithelia. Mechanistically, cell crowding inactivates the integrin-actomyosin pathway and blocks the endocytosis of fibroblast growth factor receptors (FGFRs). The disrupted FGFR endocytosis induces a marked decrease in ETV4 protein stability through ERK inactivation. Mathematical modelling demonstrates that the dynamics of cell density in a growing human embryonic stem cell epithelium precisely determines the spatiotemporal ETV4 expression pattern and, consequently, the timing and geometry of lineage development. Our findings suggest that cell crowding dynamics in a stem cell epithelium drives spatiotemporal lineage specification using ETV4 as a key mechanical transducer.
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Diferenciación Celular , Linaje de la Célula , Células Madre Embrionarias Humanas , Proteínas Proto-Oncogénicas c-ets , Factores de Transcripción , Humanos , Proteínas Proto-Oncogénicas c-ets/metabolismo , Proteínas Proto-Oncogénicas c-ets/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Células Madre Embrionarias Humanas/metabolismo , Células Madre Embrionarias Humanas/citología , Endocitosis , Proliferación Celular , Integrinas/metabolismo , Integrinas/genética , Transducción de Señal , Mecanotransducción CelularRESUMEN
Intracellular transport among organellar compartments occurs in two general ways, by membrane-bound carriers or membrane contacts. Specific circumstances that involve the coordination of these two modes of transport remain to be defined. Studying Coat Protein I (COPI) transport, we find that phosphatidylcholine with short acyl chains (sPC) is delivered through membrane contact from the endoplasmic reticulum (ER) to sites of COPI vesicle formation at the Golgi to support the fission stage. Phosphatidylinositol transfer protein beta (PITPß) plays a key role in this process, with the elucidation of this role advancing a new understanding of how PITPß acts, providing a mechanistic understanding of a specific circumstance when vesicular transport requires membrane contact, and contributing to a basic understanding of how transport carriers in a model intracellular pathway are formed.
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In utero injection of a retroviral vector into the embryonic telencephalon aided by ultrasound backscatter microscopy permits introduction of a gene of interest at an early stage of development. In this study, we compared the tissue distribution of gene expression in adult mice injected with retroviral vectors at different embryonic ages in utero. Following ultrasound image-guided gene delivery (UIGD) into the embryonic telencephalon, adult mice were subjected to whole-body luciferase imaging and immunohistochemical analysis at 6 weeks and 1 year postinjection. Luciferase activity was observed in a wide range of tissues in animals injected at embryonic age 9.5 (E9.5), whereas animals injected at E10.5 showed brain-localized reporter gene expression. These results suggest that mouse embryonic brain creates a closed and impermeable structure around E10. Therefore, by injecting a transgene before or after E10, transgene expression can be manipulated to be local or systemic. Our results also provide information that widens the applicability of UIGD beyond neuroscience studies.
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Encéfalo/embriología , Técnicas de Transferencia de Gen , Vectores Genéticos , Retroviridae/genética , Transgenes , Ultrasonografía/métodos , Animales , Encéfalo/metabolismo , Embrión de Mamíferos , Terapias Fetales/métodos , Expresión Génica , Humanos , Luciferasas/genética , Ratones , MicroinyeccionesRESUMEN
Sulfonium-Claisen rearrangement leveraged by the gold-catalyzed formation of allyl sulfonium intermediates has enabled an exceptional level of regio- and enantiocontrol for the synthesis of skipped 1,4-dienes. However, the application of cinnamyl thioether derivatives to the sulfonium-Claisen rearrangement has been unsuccessful so far due to the extensive dissociation of the cinnamyl cation. By fine-tuning bisphosphine ligands, we were able to engage cinnamyl thioethers in the [3,3]-sigmatropic rearrangement, delivering the desired 1,4-dienes in a highly enantioselective manner and in good yields. The resulting products could be transformed into optically active 2-chromanones and 4H-chromenes having a vinyl moiety.