RESUMEN
Electromagnetic wave (EMW)-absorbing materials, manufactured with composites of magnetic particles, are essential for maintaining a high complex permeability and modulated permittivity for impedance matching. However, commonly available EMW-absorbing materials are unsatisfactory owing to their low complex permeability in the high-frequency band. Herein, we report a thin, flexible EMW-absorbing membrane comprising shape-modulated FeCo nanobelts/boron nitride nanoparticles, which enables enhanced complex permeability in the S, C, and X bands (2-12 GHz). The boron nitride nanoparticles that are introduced to the FeCo nanobelts demonstrate control of the complex permittivity, leading to an effective impedance matching close to 1, consequently resulting in a high reflection loss value of -42.2 dB at 12.0 GHz with only 1.6 mm thickness. In addition, the incorporation of boron nitride nanoparticles improves the thermal conductivity for the heat dissipation of the absorbed electromagnetic wave energy. Overall, the comprehensive study of nanomaterial preparation and shape modulation technologies can lead to the fabrication of an excellent EMW-absorbing flexible composite membrane.
RESUMEN
Despite the importance of glucose and amino acids for energy metabolism, interactions between the two nutrients are not well understood. We provide evidence for a role of leucyl-tRNA synthetase 1 (LARS1) in glucose-dependent control of leucine usage. Upon glucose starvation, LARS1 was phosphorylated by Unc-51 like autophagy activating kinase 1 (ULK1) at the residues crucial for leucine binding. The phosphorylated LARS1 showed decreased leucine binding, which may inhibit protein synthesis and help save energy. Leucine that is not used for anabolic processes may be available for catabolic pathway energy generation. The LARS1-mediated changes in leucine utilization might help support cell survival under glucose deprivation. Thus, depending on glucose availability, LARS1 may help regulate whether leucine is used for protein synthesis or energy production.
Asunto(s)
Metabolismo Energético , Glucosa/metabolismo , Leucina-ARNt Ligasa/metabolismo , Leucina/metabolismo , Animales , Homólogo de la Proteína 1 Relacionada con la Autofagia/genética , Homólogo de la Proteína 1 Relacionada con la Autofagia/metabolismo , Fibroblastos , Células HEK293 , Células HeLa , Humanos , Lisosomas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones , Proteínas de Unión al GTP Monoméricas/metabolismo , Fosforilación , Transducción de SeñalRESUMEN
A fundamental question in biology is how vertebrates evolved and differ from invertebrates, and little is known about differences in the regulation of translation in the two systems. Herein, we identify a threonyl-tRNA synthetase (TRS)-mediated translation initiation machinery that specifically interacts with eIF4E homologous protein, and forms machinery that is structurally analogous to the eIF4F-mediated translation initiation machinery via the recruitment of other translation initiation components. Biochemical and RNA immunoprecipitation analyses coupled to sequencing suggest that this machinery emerged as a gain-of-function event in the vertebrate lineage, and it positively regulates the translation of mRNAs required for vertebrate development. Collectively, our findings demonstrate that TRS evolved to regulate vertebrate translation initiation via its dual role as a scaffold for the assembly of initiation components and as a selector of target mRNAs. This work highlights the functional significance of aminoacyl-tRNA synthetases in the emergence and control of higher order organisms.
Asunto(s)
Iniciación de la Cadena Peptídica Traduccional , Treonina-ARNt Ligasa/metabolismo , Secuencia de Aminoácidos , Animales , Vasos Sanguíneos/crecimiento & desarrollo , Vasos Sanguíneos/metabolismo , Factor 4E Eucariótico de Iniciación , Factor 4F Eucariótico de Iniciación/metabolismo , Factor 4G Eucariótico de Iniciación/metabolismo , Células HEK293 , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Humanos , Ratones Endogámicos C57BL , Unión Proteica , Proteínas de Unión a Caperuzas de ARN/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Especificidad de la Especie , Treonina-ARNt Ligasa/química , Vertebrados/crecimiento & desarrollo , Vertebrados/metabolismo , Pez CebraRESUMEN
Asparaginyl-tRNA synthetase (NRS) is not only essential in protein translation but also associated with autoimmune diseases. Particularly, patients with antibodies that recognize NRS often develop interstitial lung disease (ILD). However, the underlying mechanism of how NRS is recognized by immune cells and provokes inflammatory responses is not well-understood. Here, we found that the crystal structure of the unique N-terminal extension domain of human NRS (named as UNE-N, where -N denotes NRS) resembles that of the chemotactic N-terminal domain of NRS from a filarial nematode, Brugia malayi, which recruits and activates specific immune cells by interacting with CXC chemokine receptor 1 and 2. UNE-N induced migration of CC chemokine receptor 3 (CCR3)-expressing cells. The chemokine activity of UNE-N was significantly reduced by suppressing CCR3 expression with CCR3-targeting siRNA, and the loop3 region of UNE-N was shown to interact mainly with the extracellular domains of CCR3 in nuclear magnetic resonance perturbation experiments. Based on these results, evolutionarily acquired UNE-N elicits chemokine activities that would promote NRS-CCR3-mediated proinflammatory signaling in ILD.
Asunto(s)
Aspartato-ARNt Ligasa/química , Inflamación/genética , Enfermedades Pulmonares Intersticiales/genética , Aminoacil-ARN de Transferencia/química , Receptores CCR3/química , Animales , Aspartato-ARNt Ligasa/genética , Aspartato-ARNt Ligasa/inmunología , Brugia Malayi/química , Brugia Malayi/patogenicidad , Quimiocinas/química , Quimiocinas/genética , Quimiocinas/inmunología , Cristalografía por Rayos X , Humanos , Inflamación/inmunología , Inflamación/patología , Enfermedades Pulmonares Intersticiales/inmunología , Enfermedades Pulmonares Intersticiales/patología , Dominios Proteicos , Aminoacil-ARN de Transferencia/genética , Aminoacil-ARN de Transferencia/inmunología , Receptores CCR3/genética , Receptores CCR3/inmunologíaRESUMEN
Mucin1 (MUC1), a heterodimeric oncoprotein, containing tandem repeat structures with a high proportion of threonine, is aberrantly overexpressed in many human cancers including pancreatic cancer. Since the overall survival rate of pancreatic cancer patients has remained low for several decades, novel therapeutic approaches are highly needed. Intestinal mucin has been known to be affected by dietary threonine supply since de novo synthesis of mucin proteins is sensitive to luminal threonine concentration. However, it is unknown whether biosynthesis of MUC1 is regulated by threonine in human cancers. In this study, data provided suggests that threonine starvation reduces the level of MUC1 and inhibits the migration of MUC1-expressing pancreatic cancer cells. Interestingly, knockdown of threonyl-tRNA synthetase (TRS), an enzyme that catalyzes the ligation of threonine to its cognate tRNA, also suppresses MUC1 levels but not mRNA levels. The inhibitors of TRS decrease the level of MUC1 protein and prohibit the migration of MUC1-expressing pancreatic cancer cells. In addition, a positive correlation between TRS and MUC1 levels is observed in human pancreatic cancer cells. Concurrent with these results, the bioinformatics data indicate that co-expression of both TRS and MUC1 is correlated with the poor survival of pancreatic cancer patients. Taken together, these findings suggest a role for TRS in controlling MUC1-mediated cancer cell migration and provide insight into targeting TRS as a novel therapeutic approach to pancreatic cancer treatment.
Asunto(s)
Mucina-1/biosíntesis , Neoplasias Pancreáticas/patología , Treonina-ARNt Ligasa/metabolismo , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Alcoholes Grasos/farmacología , Regulación Neoplásica de la Expresión Génica , Humanos , Mucina-1/metabolismo , Neoplasias Pancreáticas/mortalidad , Análisis de Supervivencia , Treonina/metabolismo , Treonina/farmacología , Treonina-ARNt Ligasa/antagonistas & inhibidores , Treonina-ARNt Ligasa/genética , Análisis de Matrices TisularesRESUMEN
Leucyl-tRNA synthetase (LRS) is known to function as leucine sensor in the mammalian target of rapamycin complex 1 (mTORC1) pathway. However, the pathophysiological significance of its activity is not well understood. Here, we demonstrate that the leucine sensor function for mTORC1 activation of LRS can be decoupled from its catalytic activity. We identified compounds that inhibit the leucine-dependent mTORC1 pathway by specifically inhibiting the GTPase activating function of LRS, while not affecting the catalytic activity. For further analysis, we selected one compound, BC-LI-0186, which binds to the RagD interacting site of LRS, thereby inhibiting lysosomal localization of LRS and mTORC1 activity. It also effectively suppressed the activity of cancer-associated MTOR mutants and the growth of rapamycin-resistant cancer cells. These findings suggest new strategies for controlling tumor growth that avoid the resistance to existing mTOR inhibitors resulting from cancer-associated MTOR mutations.Leucyl-tRNA synthetase (LRS) is a leucine sensor of the mTORC1 pathway. Here, the authors identify inhibitors of the GTPase activating function of LRS, not affecting its catalytic activity, and demonstrate that the leucine sensor function of LRS can be a new target for mTORC1 inhibition.
Asunto(s)
Leucina-ARNt Ligasa/metabolismo , Leucina/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Proteínas de Unión al GTP Monoméricas/metabolismo , Neoplasias/enzimología , Animales , Antineoplásicos/farmacología , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Humanos , Leucina-ARNt Ligasa/genética , Diana Mecanicista del Complejo 1 de la Rapamicina/genética , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Proteínas de Unión al GTP Monoméricas/genética , Neoplasias/genética , Neoplasias/metabolismo , Unión Proteica/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Sirolimus/farmacologíaRESUMEN
A series of leucinol analogs were investigated as leucyl-tRNA synthetase-targeted mTORC1 inhibitors. Among them, compound 5, (S)-4-isobutyloxazolidin-2-one, showed the most potent inhibition on the mTORC1 pathway in a concentration-dependent manner. Compound 5 inhibited downstream phosphorylation of mTORC1 by blocking leucine-sensing ability of LRS, without affecting the catalytic activity of LRS. In addition, compound 5 exhibited cytotoxicity against rapamycin-resistant colon cancer cells, suggesting that LRS has the potential to serve as a novel therapeutic target.
Asunto(s)
Isoleucina-ARNt Ligasa/antagonistas & inhibidores , Leucina/análogos & derivados , Complejos Multiproteicos/antagonistas & inhibidores , Oxazolidinonas/farmacología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Línea Celular Tumoral , Células HEK293 , Humanos , Leucina/síntesis química , Leucina/farmacología , Diana Mecanicista del Complejo 1 de la Rapamicina , Oxazolidinonas/síntesis química , Fosforilación , Proteínas Quinasas S6 Ribosómicas/metabolismo , Sirolimus/farmacología , EstereoisomerismoRESUMEN
Ten compounds, including a new guaiane-type sesquiterpene lactone, were isolated from the aerial parts of Artemisia scoparia. The structure of the new compound was determined to be 5-hydroxyguaia-3(4),11(13),10(14)-trien-6α,12-olide, named scoparanolide. Six known sesquiterpene lactones [estafiatone, 3ß,4α-dihydroxyguaia-11(13),10(14)-dien-6α,12-olide, estafiatin, preeupatundin, 3ß-hydroxycostunolide, and ludovicin B] and three known coumarin derivatives (scopoletin, scoparone, and isofraxidin) were identified by nuclear magnetic resonance and electrospray ionization mass spectroscopy. Six known sesquiterpene lactones were found for the first time in this plant. The angiotensin I-converting enzyme inhibitory activities of coumarin derivatives and scopoletins were significantly higher compared to those of sesquiterpene lactones and quercetin.
RESUMEN
The polyketide natural product borrelidin displays antibacterial, antifungal, antimalarial, anticancer, insecticidal and herbicidal activities through the selective inhibition of threonyl-tRNA synthetase (ThrRS). How borrelidin simultaneously attenuates bacterial growth and suppresses a variety of infections in plants and animals is not known. Here we show, using X-ray crystal structures and functional analyses, that a single molecule of borrelidin simultaneously occupies four distinct subsites within the catalytic domain of bacterial and human ThrRSs. These include the three substrate-binding sites for amino acid, ATP and tRNA associated with aminoacylation, and a fourth 'orthogonal' subsite created as a consequence of binding. Thus, borrelidin competes with all three aminoacylation substrates, providing a potent and redundant mechanism to inhibit ThrRS during protein synthesis. These results highlight a surprising natural design to achieve the quadrivalent inhibition of translation through a highly conserved family of enzymes.
Asunto(s)
Proteínas de Escherichia coli/metabolismo , Treonina-ARNt Ligasa/metabolismo , Aminoacilación de ARN de Transferencia , Secuencia de Aminoácidos , Sitios de Unión , Dominio Catalítico , Cristalografía por Rayos X , Escherichia coli , Proteínas de Escherichia coli/antagonistas & inhibidores , Alcoholes Grasos/metabolismo , Humanos , Organismos Modificados Genéticamente , Treonina-ARNt Ligasa/antagonistas & inhibidores , Treonina-ARNt Ligasa/genética , Levaduras/genéticaRESUMEN
Amino acids are required for activation of the mammalian target of rapamycin (mTOR) kinase, which regulates protein translation, cell size, and autophagy. However, the amino acid sensor that directly couples intracellular amino acid-mediated signaling to mTORC1 is unknown. Here we show that leucyl-tRNA synthetase (LRS) plays a critical role in amino acid-induced mTORC1 activation by sensing intracellular leucine concentration and initiating molecular events leading to mTORC1 activation. Mutation of LRS amino acid residues important for leucine binding renders the mTORC1 pathway insensitive to intracellular levels of amino acids. We show that LRS directly binds to Rag GTPase, the mediator of amino acid signaling to mTORC1, in an amino acid-dependent manner and functions as a GTPase-activating protein (GAP) for Rag GTPase to activate mTORC1. This work demonstrates that LRS is a key mediator for amino acid signaling to mTORC1.
Asunto(s)
Leucina-ARNt Ligasa/metabolismo , Leucina/metabolismo , Proteínas/metabolismo , Transducción de Señal , Secuencia de Aminoácidos , Animales , Autofagia , Línea Celular , Tamaño de la Célula , Humanos , Leucina-ARNt Ligasa/química , Lisosomas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina , Datos de Secuencia Molecular , Complejos Multiproteicos , Biosíntesis de Proteínas , Proteínas/química , Alineación de Secuencia , Serina-Treonina Quinasas TORRESUMEN
Heat shock proteins have been implicated as endogenous activators for dendritic cells (DCs). Chronic expression of heat shock protein gp96 on cell surfaces induces significant DC activations and systemic lupus erythematosus (SLE)-like phenotypes in mice. However, its potential as a therapeutic target against SLE remains to be evaluated. In this work, we conducted chemical approach to determine whether SLE-like phenotypes can be compromised by controlling surface translocation of gp96. From screening of chemical library, we identified a compound that binds and suppresses surface presentation of gp96 by facilitating its oligomerization and retrograde transport to endoplasmic reticulum. In vivo administration of this compound reduced maturation of DCs, populations of antigen presenting cells, and activated B and T cells. The chemical treatment also alleviated the SLE-associated symptoms such as glomerulonephritis, proteinuria, and accumulation of anti-nuclear and -DNA antibodies in the SLE model mice resulting from chronic surface exposure of gp96. These results suggest that surface translocation of gp96 can be chemically controlled and gp96 as a potential therapeutic target to treat autoimmune disease like SLE.