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Background: The role of irreversible airway inflammatory damage in chronic obstructive pulmonary disease (COPD) progression is evident. Autophagy is an essential process in the cellular material metabolic cycle, and a family of resistant vegetative molecules may be involved in the COPD autophagic process. In this study, we investigated the mechanism of resistin-like molecule ß (RELMß) in COPD smoking-induced autophagy. Methods: Firstly, the expression differences of RELMß and autophagy markers between COPD and control groups were analyzed in the Gene Expression Omnibus (GEO) datasets and clinical specimens. Secondly, in vitro and in vivo experiments were conducted using immunoblotting, immunofluorescence, immunohistochemistry, and other methods to investigate the mechanism by which RELMß promotes airway inflammation through autophagy in a cigarette smoke extract-induced 16HBE cell inflammation model and a cigarette smoke-induced COPD-like mouse model. In addition, immunoprecipitation was used to analyze the binding of RELMß to the membrane protein TLR4. Results: The expression of RELMß and autophagy genes p62 and LC3B in lung tissue of COPD patients was significantly increased. RELMß can mediate the activation of autophagy in 16HBE cells, and through autophagy, it increases the expression of inflammatory cytokines in a cigarette smoke extract-induced 16HBE cell inflammation model. RELMß promotes cigarette smoke-induced COPD-like mouse airway inflammation through autophagy, and RELMß can mediate signal transduction through the cell membrane receptor TLR4. Conclusion: The RELMß binds to TLR4 to encourage signal transduction and that RELMß can promote inflammation in smoky COPD lungs through autophagy.
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The trachea tube is the exclusive route to allow gas exchange between the external environment and the lungs. Recent studies have shown the critical role of mesenchymal cells in tracheal tubulogenesis. Improved methods for studying the dynamics of the tracheal mesenchyme development are needed to investigate the cellular and molecular mechanisms during tracheal tubulogenesis. Here, we describe a detailed protocol for a systematic analysis of tracheal tube development to enable observing tracheal smooth muscle (SM) and cartilage ring formation. We describe immunostaining, confocal and stereomicroscopy imaging, and quantitative methods to study the process of tracheal SM and cartilage ring development, including SM cell alignment, polarization, and changes in cell shape as well as mesenchymal condensation. The technologies and approaches described here not only improve analysis of the patterning of the developing trachea but also help uncover the mechanisms underlying airway disease. This protocol also provides a useful technique to analyze cell organization, polarity, and nuclear shape in other organ systems.
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Cardiopulmonary complications are major drivers of mortality caused by the SARS-CoV-2 virus. Interleukin-18, an inflammasome-induced cytokine, has emerged as a novel mediator of cardiopulmonary pathologies but its regulation via SARS-CoV-2 signaling remains unknown. Based on a screening panel, IL-18 was identified amongst 19 cytokines to stratify mortality and hospitalization burden in patients hospitalized with COVID-19. Supporting clinical data, administration of SARS-CoV-2 Spike 1 (S1) glycoprotein or receptor-binding domain (RBD) proteins into human angiotensin-converting enzyme 2 (hACE2) transgenic mice induced cardiac fibrosis and dysfunction associated with higher NF-κB phosphorylation (pNF-κB) and cardiopulmonary-derived IL-18 and NLRP3 expression. IL-18 inhibition via IL-18BP resulted in decreased cardiac pNF-κB and improved cardiac fibrosis and dysfunction in S1- or RBD-exposed hACE2 mice. Through in vivo and in vitro work, both S1 and RBD proteins induced NLRP3 inflammasome and IL-18 expression by inhibiting mitophagy and increasing mitochondrial reactive oxygenation species. Enhancing mitophagy prevented Spike protein-mediated IL-18 expression. Moreover, IL-18 inhibition reduced Spike protein-mediated pNF-κB and EC permeability. Overall, the link between reduced mitophagy and inflammasome activation represents a novel mechanism during COVID-19 pathogenesis and suggests IL-18 and mitophagy as potential therapeutic targets.
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COVID-19 , Glicoproteína de la Espiga del Coronavirus , Humanos , Ratones , Animales , Glicoproteína de la Espiga del Coronavirus/metabolismo , SARS-CoV-2/metabolismo , COVID-19/genética , Inflamasomas/genética , Inflamasomas/metabolismo , Interleucina-18/genética , Proteína con Dominio Pirina 3 de la Familia NLR/genética , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Mitofagia/genética , Inflamación/genética , Inflamación/metabolismo , CitocinasRESUMEN
Although previous studies have revealed that synonymous mutations contribute to various human diseases, distinguishing deleterious synonymous mutations from benign ones is still a challenge in medical genomics. Recently, computational tools have been introduced to predict the harmfulness of synonymous mutations. However, most of these computational tools rely on balanced training sets without considering abundant negative samples that could result in deficient performance. In this study, we propose a computational model that uses a selective ensemble to predict deleterious synonymous mutations (seDSM). We construct several candidate base classifiers for the ensemble using balanced training subsets randomly sampled from the imbalanced benchmark training sets. The diversity measures of the base classifiers are calculated by the pairwise diversity metrics, and the classifiers with the highest diversities are selected for integration using soft voting for synonymous mutation prediction. We also design two strategies for filling in missing values in the imbalanced dataset and constructing models using different pairwise diversity metrics. The experimental results show that a selective ensemble based on double fault with the ensemble strategy EKNNI for filling in missing values is the most effective scheme. Finally, using 40-dimensional biology features, we propose a novel model based on a selective ensemble for predicting deleterious synonymous mutations (seDSM). seDSM outperformed other state-of-the-art methods on the independent test sets according to multiple evaluation indicators, indicating that it has an outstanding predictive performance for deleterious synonymous mutations. We hope that seDSM will be useful for studying deleterious synonymous mutations and advancing our understanding of synonymous mutations. The source code of seDSM is freely accessible at https://github.com/xialab-ahu/seDSM.git.
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Genómica , Mutación Silenciosa , Humanos , Genómica/métodos , Programas Informáticos , AlgoritmosRESUMEN
The tracheal epithelium is a primary target for pulmonary diseases as it provides a conduit for air flow between the environment and the lung lobes. The cellular and molecular mechanisms underlying airway epithelial cell proliferation and differentiation remain poorly understood. Hedgehog (HH) signaling orchestrates communication between epithelial and mesenchymal cells in the lung, where it modulates stromal cell proliferation, differentiation and signaling back to the epithelium. Here, we reveal a previously unreported autocrine function of HH signaling in airway epithelial cells. Epithelial cell depletion of the ligand sonic hedgehog (SHH) or its effector smoothened (SMO) causes defects in both epithelial cell proliferation and differentiation. In cultured primary human airway epithelial cells, HH signaling inhibition also hampers cell proliferation and differentiation. Epithelial HH function is mediated, at least in part, through transcriptional activation, as HH signaling inhibition leads to downregulation of cell type-specific transcription factor genes in both the mouse trachea and human airway epithelial cells. These results provide new insights into the role of HH signaling in epithelial cell proliferation and differentiation during airway development.
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Comunicación Autocrina/fisiología , Diferenciación Celular , Proliferación Celular , Proteínas Hedgehog/metabolismo , Transducción de Señal/genética , Animales , Células Cultivadas , Regulación hacia Abajo , Embrión de Mamíferos/citología , Embrión de Mamíferos/metabolismo , Células Epiteliales/citología , Células Epiteliales/metabolismo , Proteínas Hedgehog/deficiencia , Proteínas Hedgehog/genética , Humanos , Pulmón/crecimiento & desarrollo , Pulmón/metabolismo , Pulmón/patología , Ratones , Ratones Noqueados , Receptor Smoothened/deficiencia , Receptor Smoothened/genética , Receptor Smoothened/metabolismo , Tráquea/citología , Tráquea/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Treatments for pulmonary fibrosis (PF) are ineffective because its molecular pathogenesis and therapeutic targets are unclear. Here, we show that the expression of low-density lipoprotein receptor (LDLR) was significantly decreased in alveolar type II (ATII) and fibroblast cells, whereas it was increased in endothelial cells from systemic sclerosis-related PF (SSc-PF) patients and idiopathic PF (IPF) patients compared with healthy controls. However, the plasma levels of low-density lipoprotein (LDL) increased in SSc-PF and IPF patients. The disrupted LDL-LDLR metabolism was also observed in four mouse PF models. Upon bleomycin (BLM) treatment, Ldlr-deficient (Ldlr-/-) mice exhibited remarkably higher LDL levels, abundant apoptosis, increased fibroblast-like endothelial and ATII cells and significantly earlier and more severe fibrotic response compared to wild-type mice. In vitro experiments revealed that apoptosis and TGF-ß1 production were induced by LDL, while fibroblast-like cell accumulation and ET-1 expression were induced by LDLR knockdown. Treatment of fibroblasts with LDL or culture medium derived from LDL-pretreated endothelial or epithelial cells led to obvious fibrotic responses in vitro. Similar results were observed after LDLR knockdown operation. These results suggest that disturbed LDL-LDLR metabolism contributes in various ways to the malfunction of endothelial and epithelial cells, and fibroblasts during pulmonary fibrogenesis. In addition, pharmacological restoration of LDLR levels by using a combination of atorvastatin and alirocumab inhibited BLM-induced LDL elevation, apoptosis, fibroblast-like cell accumulation and mitigated PF in mice. Therefore, LDL-LDLR may serve as an important mediator in PF, and LDLR enhancing strategies may have beneficial effects on PF.
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Lipoproteínas LDL/genética , Fibrosis Pulmonar/etiología , Receptores de LDL/metabolismo , Animales , Modelos Animales de Enfermedad , Lipoproteínas LDL/efectos de los fármacos , Ratones , Ratones Endogámicos C57BL/genética , Ratones Endogámicos C57BL/metabolismo , Fibrosis Pulmonar/genéticaRESUMEN
The current COVID-19 pandemic, caused by SARS-CoV-2, poses a serious public health threat. Effective therapeutic and prophylactic treatments are urgently needed. Angiotensin-converting enzyme 2 (ACE2) is a functional receptor for SARS-CoV-2, which binds to the receptor binding domain (RBD) of SARS-CoV-2 spike protein. Here, we developed recombinant human ACE2-Fc fusion protein (hACE2-Fc) and a hACE2-Fc mutant with reduced catalytic activity. hACE2-Fc and the hACE2-Fc mutant both efficiently blocked entry of SARS-CoV-2, SARS-CoV, and HCoV-NL63 into hACE2-expressing cells and inhibited SARS-CoV-2 S protein-mediated cell-cell fusion. hACE2-Fc also neutralized various SARS-CoV-2 strains with enhanced infectivity including D614G and V367F mutations, as well as the emerging SARS-CoV-2 variants, B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617.1 (Kappa), and B.1.617.2 (Delta), demonstrating its potent and broad-spectrum antiviral effects. In addition, hACE2-Fc proteins protected HBE from SARS-CoV-2 infection. Unlike RBD-targeting neutralizing antibodies, hACE2-Fc treatment did not induce the development of escape mutants. Furthermore, both prophylactic and therapeutic hACE2-Fc treatments effectively protected mice from SARS-CoV-2 infection, as determined by reduced viral replication, weight loss, histological changes, and inflammation in the lungs. The protection provided by hACE2 showed obvious dose-dependent efficacy in vivo. Pharmacokinetic data indicated that hACE2-Fc has a relative long half-life in vivo compared to soluble ACE2, which makes it an excellent candidate for prophylaxis and therapy for COVID-19 as well as for SARS-CoV and HCoV-NL63 infections.
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Severe COVID-19 patient airways plugged by MUC5AC-containing mucus exhibit hyperplasia of goblet cells, and hypoplasia of multiciliated cells and club cells, as well as significantly reduced CC16 and MUC5B levels, and increased IL-13 levels https://bit.ly/2M2NcdO.
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Cardiovascular disease is a serious threat to human health and a leading cause of mortality worldwide. Recent years have witnessed exciting progress in the understanding of heart formation and development, enabling cardiac biologists to make significant advance in the field of therapeutic heart regeneration. Most of our understanding of heart development and regeneration, including the genes and signaling pathways, are driven by pioneering works in non-mammalian model organisms, such as fruit fly, fish, frog, and chicken. Compared to mammalian animal models, non-mammalian model organisms have special advantages in high-throughput applications such as disease modeling, drug discovery, and cardiotoxicity screening. Genetically engineered animals of cardiovascular diseases provide valuable tools to investigate the molecular and cellular mechanisms of pathogenesis and to evaluate therapeutic strategies. A large number of congenital heart diseases (CHDs) non-mammalian models have been established and tested for the genes and signaling pathways involved in the diseases. Here, we reviewed the mechanisms of heart development and regeneration revealed by these models, highlighting the advantages of non-mammalian models as tools for cardiac research. The knowledge from these animal models will facilitate therapeutic discoveries and ultimately serve to accelerate translational medicine.
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BACKGROUND: Coronavirus disease 2019 (COVID-19) has been a global pandemic disease, with more than 4 million cases and nearly 300,000 deaths. Little is known about COVID-19 in patients with chronic obstructive pulmonary disease (COPD). We aimed to evaluate the influence of preexisting COPD on the progress and outcomes of COVID-19. METHODS: This was a multicenter, retrospective, observational study. We enrolled 1,048 patients aged 40 years and above, including 50 patients with COPD and 998 patients without COPD, and with COVID-19 confirmed via high-throughput sequencing or real-time reverse transcription-polymerase chain reaction, between December 11, 2019 and February 20, 2020. We collected data of demographics, pathologic test results, radiologic imaging, and treatments. The primary outcomes were composite endpoints determined by admission to an intensive care unit, the use of mechanical ventilation, or death. RESULTS: Compared with patients who had COVID-19 but not COPD, those with COPD had higher rates of fatigue (56.0% vs. 40.2%), dyspnea (66.0% vs. 26.3%), diarrhea (16.0% vs. 3.6%), and unconsciousness (8.0% vs. 1.7%) and a significantly higher proportion of increased activated partial thromboplastin time (23.5% vs. 5.2%) and D-dimer (65.9% vs. 29.3%), as well as ground-glass opacities (77.6% vs. 60.3%), local patchy shadowing (61.2% vs. 41.4%), and interstitial abnormalities (51.0% vs. 19.8%) on chest computed tomography. Patients with COPD were more likely to develop bacterial or fungal coinfection (20.0% vs. 5.9%), acute respiratory distress syndrome (ARDS) (20.0% vs. 7.3%), septic shock (14.0% vs. 2.3%), or acute renal failure (12.0% vs. 1.3%). Patients with COPD and COVID-19 had a higher risk of reaching the composite endpoints [hazard ratio (HR): 2.17, 95% confidence interval (CI): 1.40-3.38; P=0.001] or death (HR: 2.28, 95% CI: 1.15-4.51; P=0.019), after adjustment. CONCLUSIONS: In this study, patients with COPD who developed COVID-19 showed a higher risk of admission to the intensive care unit, mechanical ventilation, or death.
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Goblet cell metaplasia and mucus hypersecretion are observed in many pulmonary diseases, including asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. However, the regulation of goblet cell differentiation remains unclear. Here, we identify a regulator of this process in an N-ethyl-N-nitrosourea (ENU) screen for modulators of postnatal lung development; Ryk mutant mice exhibit lung inflammation, goblet cell hyperplasia, and mucus hypersecretion. RYK functions as a WNT coreceptor, and, in the developing lung, we observed high RYK expression in airway epithelial cells and moderate expression in mesenchymal cells as well as in alveolar epithelial cells. From transcriptomic analyses and follow-up studies, we found decreased WNT/ß-catenin signaling activity in the mutant lung epithelium. Epithelial-specific Ryk deletion causes goblet cell hyperplasia and mucus hypersecretion but not inflammation, while club cell-specific Ryk deletion in adult stages leads to goblet cell hyperplasia and mucus hypersecretion during regeneration. We also found that the airway epithelium of COPD patients often displays goblet cell metaplastic foci, as well as reduced RYK expression. Altogether, our findings reveal that RYK plays important roles in maintaining the balance between airway epithelial cell populations during development and repair, and that defects in RYK expression or function may contribute to the pathogenesis of human lung diseases.
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Diferenciación Celular/fisiología , Células Caliciformes , Pulmón , Proteínas Tirosina Quinasas Receptoras/metabolismo , Vía de Señalización Wnt/fisiología , Células A549 , Animales , Células Caliciformes/citología , Células Caliciformes/metabolismo , Células Caliciformes/fisiología , Humanos , Hiperplasia/metabolismo , Hiperplasia/patología , Pulmón/citología , Pulmón/crecimiento & desarrollo , Pulmón/metabolismo , Ratones , Moco/metabolismo , Neumonía/metabolismo , Neumonía/patología , Enfermedad Pulmonar Obstructiva Crónica/metabolismo , Enfermedad Pulmonar Obstructiva Crónica/patología , beta Catenina/metabolismoRESUMEN
Centriolar satellites are non-membrane cytoplasmic granules that deliver proteins to centrosome during centrosome biogenesis and ciliogenesis. Centriolar satellites are highly dynamic during cell cycle or ciliogenesis and how they are regulated remains largely unknown. We report here that sorting nexin 17 (SNX17) regulates the homeostasis of a subset of centriolar satellite proteins including PCM1, CEP131, and OFD1 during serum-starvation-induced ciliogenesis. Mechanistically, SNX17 recruits the deubiquitinating enzyme USP9X to antagonize the mindbomb 1 (MIB1)-induced ubiquitination and degradation of PCM1. SNX17 deficiency leads to enhanced degradation of USP9X as well as PCM1 and disrupts ciliogenesis upon serum starvation. On the other hand, SNX17 is dispensable for the homeostasis of PCM1 and USP9X in serum-containing media. These findings reveal a SNX17/USP9X mediated pathway essential for the homeostasis of centriolar satellites under serum starvation, and provide insight into the mechanism of USP9X in ciliogenesis, which may lead to a better understating of USP9X-deficiency-related human diseases such as X-linked mental retardation and neurodegenerative diseases.
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Autoantígenos/metabolismo , Proteínas de Ciclo Celular/metabolismo , Cilios/fisiología , Medio de Cultivo Libre de Suero/farmacología , Nexinas de Clasificación/metabolismo , Ubiquitina Tiolesterasa/metabolismo , Ubiquitina-Proteína Ligasas/antagonistas & inhibidores , Diferenciación Celular/genética , Células Cultivadas , Cilios/efectos de los fármacos , Medio de Cultivo Libre de Suero/química , Células HEK293 , Humanos , Unión Proteica , Procesamiento Proteico-Postraduccional/genética , Proteolisis , Nexinas de Clasificación/genética , Ubiquitina Tiolesterasa/genética , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación/genéticaRESUMEN
Epithelial tubes, comprised of polarised epithelial cells around a lumen, are crucial for organ function. However, the molecular mechanisms underlying tube formation remain largely unknown. Here, we report on the function of fibrillin (FBN)2, an extracellular matrix (ECM) glycoprotein, as a critical regulator of tracheal tube formation.We performed a large-scale forward genetic screen in mouse to identify regulators of respiratory organ development and disease. We identified Fbn2 mutants which exhibit shorter and narrowed tracheas as well as defects in tracheal smooth muscle cell alignment and polarity.We found that FBN2 is essential for elastic fibre formation and Fibronectin accumulation around tracheal smooth muscle cells. These processes appear to be regulated at least in part through inhibition of p38-mediated upregulation of matrix metalloproteinases (MMPs), as pharmacological decrease of p38 phosphorylation or MMP activity partially attenuated the Fbn2 mutant tracheal phenotypes. Analysis of human tracheal tissues indicates that a decrease in ECM proteins, including FBN2 and Fibronectin, is associated with tracheomalacia.Our findings provide novel insights into the role of ECM homeostasis in mesenchymal cell polarisation during tracheal tubulogenesis.
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Matriz Extracelular/metabolismo , Fibrilina-2/metabolismo , Músculo Liso/embriología , Miocitos del Músculo Liso/citología , Tráquea/embriología , Animales , Embrión de Mamíferos , Femenino , Fibrilina-2/genética , Fibronectinas/metabolismo , Regulación del Desarrollo de la Expresión Génica , Homeostasis , Masculino , Ratones , Ratones Endogámicos C57BL , Músculo Liso/citología , Fenotipo , Fosforilación , Transducción de Señal , Tráquea/citologíaRESUMEN
Impaired alveolar formation and maintenance are features of many pulmonary diseases that are associated with significant morbidity and mortality. In a forward genetic screen for modulators of mouse lung development, we identified the non-muscle myosin II heavy chain gene, Myh10. Myh10 mutant pups exhibit cyanosis and respiratory distress, and die shortly after birth from differentiation defects in alveolar epithelium and mesenchyme. From omics analyses and follow up studies, we find decreased Thrombospondin expression accompanied with increased matrix metalloproteinase activity in both mutant lungs and cultured mutant fibroblasts, as well as disrupted extracellular matrix (ECM) remodeling. Loss of Myh10 specifically in mesenchymal cells results in ECM deposition defects and alveolar simplification. Notably, MYH10 expression is downregulated in the lung of emphysema patients. Altogether, our findings reveal critical roles for Myh10 in alveologenesis at least in part via the regulation of ECM remodeling, which may contribute to the pathogenesis of emphysema.
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Matriz Extracelular/metabolismo , Enfermedades Pulmonares/metabolismo , Cadenas Pesadas de Miosina/deficiencia , Miosina Tipo IIB no Muscular/deficiencia , Secuencia de Aminoácidos , Animales , Regulación hacia Abajo/genética , Enfisema/patología , Etilnitrosourea , Femenino , Enfermedades Pulmonares/patología , Masculino , Metaloproteinasa 2 de la Matriz/metabolismo , Mesodermo/metabolismo , Ratones Endogámicos C57BL , Mutagénesis/genética , Mutación Missense/genética , Cadenas Pesadas de Miosina/química , Cadenas Pesadas de Miosina/genética , Cadenas Pesadas de Miosina/metabolismo , Miosina Tipo IIB no Muscular/química , Miosina Tipo IIB no Muscular/genética , Miosina Tipo IIB no Muscular/metabolismo , Organogénesis , Fenotipo , Alveolos Pulmonares/embriología , Alveolos Pulmonares/metabolismo , Regulación hacia Arriba/genéticaRESUMEN
The transition-metal-free synthesis of unsymmetrical and highly functionalized triarylmethanes through arylation of the situ generated o-QMs from diarylmethyl p-tolyl sulfones with aryl zinc reagents is described. Alkyl zinc reagents are also well tolerated in this reaction. Additionally, the straightforward synthesis of the analogue of the antituberculosis agent A and the key precursor of the anti-breast-cancer agent B are achieved by this strategy.
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Antibacterianos/química , Hidrocarburos Aromáticos/química , Sulfonas/química , Zinc/química , Alquilación , Catálisis , Indicadores y Reactivos/químicaRESUMEN
Tubulogenesis is essential for the formation and function of internal organs. One such organ is the trachea, which allows gas exchange between the external environment and the lungs. However, the cellular and molecular mechanisms underlying tracheal tube development remain poorly understood. Here, we show that the potassium channel KCNJ13 is a critical modulator of tracheal tubulogenesis. We identify Kcnj13 in an ethylnitrosourea forward genetic screen for regulators of mouse respiratory organ development. Kcnj13 mutants exhibit a shorter trachea as well as defective smooth muscle (SM) cell alignment and polarity. KCNJ13 is essential to maintain ion homeostasis in tracheal SM cells, which is required for actin polymerization. This process appears to be mediated, at least in part, through activation of the actin regulator AKT, as pharmacological increase of AKT phosphorylation ameliorates the Kcnj13-mutant trachea phenotypes. These results provide insight into the role of ion homeostasis in cytoskeletal organization during tubulogenesis.
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Morfogénesis/genética , Músculo Liso/metabolismo , Miocitos del Músculo Liso/metabolismo , Canales de Potasio de Rectificación Interna/genética , Proteínas Proto-Oncogénicas c-akt/genética , Tráquea/metabolismo , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/ultraestructura , Animales , Polaridad Celular , Embrión de Mamíferos , Femenino , Regulación del Desarrollo de la Expresión Génica , Transporte Iónico , Ratones Noqueados , Músculo Liso/citología , Miocitos del Músculo Liso/citología , Fosforilación , Polimerizacion , Canales de Potasio de Rectificación Interna/deficiencia , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Tráquea/citología , Tráquea/crecimiento & desarrolloRESUMEN
UNLABELLED: Sorting nexin (SNX) family proteins are best characterized for their abilities to regulate protein trafficking during processes such as endocytosis of membrane receptors, endosomal sorting, and protein degradation, but their in vivo functions remain largely unknown. We started to investigate the biological functions of SNXs using the zebrafish model. In this study, we demonstrated that SNX7 was essential for embryonic liver development. Hepatoblasts were specified normally, and the proliferation of these cells was not affected when SNX7 was knocked down by gene-specific morpholinos; however, they underwent massive apoptosis during the early budding stage. SNX7 mainly regulated the survival of cells in the embryonic liver and did not affect the viability of cells in other endoderm-derived organs. We further demonstrated that down-regulation of SNX7 by short interfering RNAs induced apoptosis in cell culture. At the molecular level, the cellular FLICE-like inhibitory protein (c-FLIP)/caspase 8 pathway was activated when SNX7 was down-regulated. Furthermore, overexpression of c-FLIP(S) was able to rescue the SNX7 knockdown-induced liver defect. CONCLUSION: SNX7 is a liver-enriched antiapoptotic protein that is indispensable for the survival of hepatoblasts during zebrafish early embryogenesis.
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Apoptosis , Hígado/embriología , Nexinas de Clasificación/fisiología , Pez Cebra/embriología , Animales , Caspasa 8/fisiología , Proliferación Celular , Supervivencia Celular , Nexinas de Clasificación/genéticaRESUMEN
BACKGROUND: Notch is one of the most important signaling pathways involved in cell fate determination. Activation of the Notch pathway requires the binding of a membrane-bound ligand to the Notch receptor in the adjacent cell which induces proteolytic cleavages and the activation of the receptor. A unique feature of the Notch signaling is that processes such as modification, endocytosis or recycling of the ligand have been reported to play critical roles during Notch signaling, however, the underlying molecular mechanism appears context-dependent and often controversial. RESULTS: Here we identified SNX17 as a novel regulator of the Notch pathway. SNX17 is a sorting nexin family protein implicated in vesicular trafficking and we find it is specifically required in the ligand-expressing cells for Notch signaling. Mechanistically, SNX17 regulates the protein level of Jag1a on plasma membrane by binding to Jag1a and facilitating the retromer-dependent recycling of the ligand. In zebrafish, inhibition of this SNX17-mediated Notch signaling pathway results in defects in neurogenesis as well as pancreas development. CONCLUSIONS: Our results reveal that SNX17, by acting as a cargo-specific adaptor, promotes the retromer dependent recycling of Jag1a and Notch signaling and this pathway is involved in cell fate determination during zebrafish neurogenesis and pancreas development.
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Sorting nexins (SNXs) are phosphoinositide-binding proteins implicated in the sorting of various membrane proteins in vitro, but the in vivo functions of them remain largely unknown. We reported previously that SNX10 is a unique member of the SNX family genes in that it has vacuolation activity in cells. We investigate the biological function of SNX10 by loss-of-function assay in this study and demonstrate that SNX10 is required for the formation of primary cilia in cultured cells. In zebrafish, SNX10 is involved in ciliogenesis in the Kupffer's vesicle and essential for left-right patterning of visceral organs. Mechanistically, SNX10 interacts with V-ATPase complex and targets it to the centrosome where ciliogenesis is initiated. Like SNX10, V-ATPase regulates ciliogenesis in vitro and in vivo and does so synergistically with SNX10. We further discover that SNX10 and V-ATPase regulate the ciliary trafficking of Rab8a, which is a critical regulator of ciliary membrane extension. These results identify an SNX10/V-ATPase-regulated vesicular trafficking pathway that is crucial for ciliogenesis, and reveal that SNX10/V-ATPase, through the regulation of cilia formation in various organs, play an essential role during early embryonic development.
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Nexinas de Clasificación/metabolismo , ATPasas de Translocación de Protón Vacuolares/metabolismo , Proteínas de Pez Cebra/metabolismo , Animales , Tipificación del Cuerpo , Línea Celular Tumoral , Centrosoma/fisiología , Cilios/fisiología , Desarrollo Embrionario , Humanos , Morfogénesis , Unión Proteica , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Nexinas de Clasificación/antagonistas & inhibidores , Nexinas de Clasificación/genética , ATPasas de Translocación de Protón Vacuolares/antagonistas & inhibidores , ATPasas de Translocación de Protón Vacuolares/genética , Vacuolas/metabolismo , Vacuolas/fisiología , Pez Cebra , Proteínas de Pez Cebra/antagonistas & inhibidores , Proteínas de Pez Cebra/genética , Proteínas de Unión al GTP rab/metabolismoRESUMEN
OBJECTIVE: To establish a SPE-HPLC method for the determination and pharmacokinetic study of evodiamine and rutacarpine in rat plasma. METHOD: A Kromasil C18 column (4.6 mm x 250 mm, 5 microm) was used with acetonitrile-water-tetrahydrofuran-acetic acid (51:48:1:0.1) as a mobile phase and at a flow rate of 1 mL x min(-1), and the UV detection was at 225 nm. The column temperature was 35 degrees C. After the analytes were extracted from the plasma of rats by solid phase extraction (SPE), the content of evodiamine and rutaecarpine was measuared by HPLC method using halcinonide as an internal standard solution. RESULT: After transdermal administration to rats, the pharmacokinetic behavior of evodiamine and rutaecarpine belongs to the one-compartment model. The main pharmacokinetic parameters was as follows: K(a) 0.224 h(-1) and 0.220 h(-1), K(e) 0.114 h(-1) and 0.118 h(-1), C(max) 0.211 mg x L(-1) and 0.272 mg x L(-1), T(peak) 6.132 h and 6.102 h, respectively. CONCLUSION: The method in this study is simple, rapid and sensitive. It is proved to be suitable for pharmacokinetic study of evodiamine and rutaecarpine.