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How early events in effector T cell (TEFF) subsets tune memory T cell (TMEM) responses remains incompletely understood. Here, we systematically investigated metabolic factors in fate determination of TEFF and TMEM cells using in vivo pooled CRISPR screening, focusing on negative regulators of TMEM responses. We found that amino acid transporters Slc7a1 and Slc38a2 dampened the magnitude of TMEM differentiation, in part through modulating mTORC1 signaling. By integrating genetic and systems approaches, we identified cellular and metabolic heterogeneity among TEFF cells, with terminal effector differentiation associated with establishment of metabolic quiescence and exit from the cell cycle. Importantly, Pofut1 (protein-O-fucosyltransferase-1) linked GDP-fucose availability to downstream Notch-Rbpj signaling, and perturbation of this nutrient signaling axis blocked terminal effector differentiation but drove context-dependent TEFF proliferation and TMEM development. Our study establishes that nutrient uptake and signaling are key determinants of T cell fate and shape the quantity and quality of TMEM responses.
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Aminoácidos/metabolismo , Linfocitos T CD8-positivos/citología , Memoria Inmunológica , Transducción de Señal , Sistemas de Transporte de Aminoácidos/metabolismo , Animales , Linfocitos T CD8-positivos/inmunología , Sistemas CRISPR-Cas , Ciclo Celular , Diferenciación Celular , Modelos Animales de Enfermedad , Femenino , Técnicas de Sustitución del Gen , Coriomeningitis Linfocítica/inmunología , Masculino , Ratones , Ratones Transgénicos , Células Precursoras de Linfocitos T/citologíaRESUMEN
Ascorbate plays an indispensable role in plants, functioning as both an antioxidant and a cellular redox buffer. It is widely acknowledged that the ascorbate biosynthesis in the photosynthetic tissues of land plants is governed by light-mediated regulation of the D-mannose/L-galactose (D-Man/L-Gal) pathway. At the core of this light-dependent regulation lies the VTC2 gene, encoding the rate-limiting enzyme GDP-L-Gal phosphorylase. The VTC2 expression is regulated by signals via the photosynthetic electron transport system. In this study, we directed our attention to the liverwort Marchantia polymorpha, representing one of the basal land plants, enabling us to conduct an in-depth analysis of its ascorbate biosynthesis. The M. polymorpha genome harbors a solitary gene for each enzyme involved in the D-Man/L-Gal pathway, including VTC2, along with three lactonase orthologs, which may be involved in the alternative ascorbate biosynthesis pathway. Through supplementation experiments with potential precursors, we observed that only L-Gal exhibited effectiveness in ascorbate biosynthesis. Furthermore, the generation of VTC2-deficient mutants through genome editing unveiled the inability of thallus regeneration in the absence of L-Gal supplementation, thereby revealing the importance of the D-Man/L-Gal pathway in ascorbate biosynthesis within M. polymorpha. Interestingly, gene expression analyses unveiled a distinct characteristic of M. polymorpha, where none of the genes associated with the D-Man/L-Gal pathway, including VTC2, showed upregulation in response to light, unlike other known land plants. This study sheds light on the exceptional nature of M. polymorpha as a land plant that has evolved distinctive mechanisms concerning ascorbate biosynthesis and its regulation.
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Marchantia , Humanos , Marchantia/genética , Marchantia/metabolismo , Galactosa/metabolismo , Manosa/metabolismo , Antioxidantes/metabolismo , Estrés Oxidativo , Plantas/metabolismo , Regulación de la Expresión Génica de las PlantasRESUMEN
Ascorbate is a major plant metabolite that plays crucial roles in various processes, from reactive oxygen scavenging to epigenetic regulation. However, to what extent and how ascorbate modulates metabolism is largely unknown. We investigated the consequences of chloroplastic and total cellular ascorbate-deficiencies by studying chloroplastic ascorbate-transporter mutant lines lacking PHOSPHATE TRANSPORTER 4; 4 (PHT4; 4) , and the ascorbate-deficient vtc2-4 mutant of Arabidopsis (Arabidopsis thaliana). Under regular growth conditions, both ascorbate deficiencies caused minor alterations in photosynthesis, with no apparent signs of oxidative damage. In contrast, metabolomics analysis revealed global and largely overlapping alterations in the metabolome profiles of both ascorbate-deficiency mutants, suggesting that chloroplastic ascorbate modulates plant metabolism. We observed significant alterations in amino acid metabolism, particularly in arginine metabolism, activation of nucleotide salvage pathways, and changes in secondary metabolism. In addition, proteome-wide analysis of thermostability revealed that ascorbate may interact with enzymes involved in arginine metabolism, the Calvin-Benson cycle, and several photosynthetic electron transport components. Overall, our results suggest that, independently of oxidative stress, chloroplastic ascorbate modulates the activity of diverse metabolic pathways in vascular plants and may act as an internal metabolic signal.
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This paper provides a picture of how societies in the G7 countries have responded to the COVID-19 pandemic. Our point of departure is to examine the effects of the pandemic in terms of four fundamental normative sources for well-being: Solidarity (S; willingness for social cooperation), Agency (A; empowerment to shape one's prospects through one's own efforts), GDP (G), and Environmental Performance (E)-SAGE for short. The normative foundations of SAGE are communitarianism, classical liberalism, materialistic utilitarianism, and ecoethics. We find that although G and E responded predictably and uniformly to the pandemic (such as G declining and carbon emissions improving), the societal responses were strikingly different. Societies that are cohesive and empowered (high S and A) may be expected to cope with the pandemic better than those that are fragmented and disempowered (low S and A). Furthermore, the pandemic has had diverse effects on S and A; while some societies became cohering and empowering (rising S and A), others became fragmenting and disempowering (falling S and A), and yet others became fragmenting and empowering. We also show that most G7 countries experienced greater tribalization (measured as the difference between inward S and outward S) during the pandemic. These trends are a matter of concern since they suggest that the willingness and perceived ability to address collective challenges collectively have waned. The analysis also suggests that governments' social policies may have an important role to play alongside economic and health policies in coping with the pandemic.
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COVID-19 , Pandemias , Política Pública , Conducta Social , Adaptación Psicológica , COVID-19/economía , COVID-19/psicología , Conducta Cooperativa , Empoderamiento , Producto Interno Bruto , Humanos , Responsabilidad SocialRESUMEN
Slc35c1 encodes an antiporter that transports GDP-fucose into the Golgi and returns GMP to the cytoplasm. The closely related gene Slc35c2 encodes a putative GDP-fucose transporter and promotes Notch fucosylation and Notch signaling in cultured cells. Here, we show that HEK293T cells lacking SLC35C1 transferred reduced amounts of O-fucose to secreted epidermal growth factor-like repeats from NOTCH1 or secreted thrombospondin type I repeats from thrombospondin 1. However, cells lacking SLC35C2 did not exhibit reduced fucosylation of these epidermal growth factor-like repeats or thrombospondin type I repeats. To investigate SLC35C2 functions in vivo, WW6 embryonic stem cells were targeted for Slc35c2. Slc35c2[-/-] mice were viable and fertile and exhibited no evidence of defective Notch signaling during skeletal or T cell development. By contrast, mice with inactivated Slc35c1 exhibited perinatal lethality and marked skeletal defects in late embryogenesis, typical of defective Notch signaling. Compound Slc35c1[-/-]Slc35c2[-/-] mutants were indistinguishable in skeletal phenotype from Slc35c1[-/-] embryos and neonates. Double mutants did not exhibit the exacerbated skeletal defects predicted if SLC35C2 was functionally important for Notch signaling in vivo. In addition, NOTCH1 immunoprecipitated from Slc35c1[-/-]Slc35c2[-/-] neonatal lung carried fucose detected by binding of Aleuria aurantia lectin. Given that the absence of both SLC35C1, a known GDP-fucose transporter, and SLC35C2, a putative GDP-fucose transporter, did not lead to afucosylated NOTCH1 nor to the severe Notch signaling defects and embryonic lethality expected if all GDP-fucose transport were abrogated, at least one more mechanism of GDP-fucose transport into the secretory pathway must exist in mammals.
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Fucosa , Proteínas de Transporte de Monosacáridos , Proteínas de Transporte de Nucleótidos , Animales , Femenino , Humanos , Ratones , Embarazo , Factor de Crecimiento Epidérmico , Fucosa/metabolismo , Células HEK293 , Proteínas de Transporte de Monosacáridos/genética , Proteínas de Neoplasias , Proteínas de Transporte de Nucleótidos/genética , Trombospondinas/metabolismo , Ratones Noqueados , Receptor Notch1/metabolismo , Transducción de SeñalRESUMEN
Ascorbate is involved in numerous vital processes, in particular in response to abiotic but also biotic stresses whose frequency and amplitude increase with climate change. Ascorbate levels vary greatly depending on species, tissues, or stages of development, but also in response to stress. Since its discovery, the ascorbate biosynthetic pathway has been intensely studied and it appears that GDP-l-galactose phosphorylase (GGP) is the enzyme with the greatest role in the control of ascorbate biosynthesis. Like other enzymes of this pathway, its expression is induced by various environmental and also developmental factors. Although mRNAs encoding it are among the most abundant in the transcriptome, the protein is only present in very small quantities. In fact, GGP translation is repressed by a negative feedback mechanism involving a small open reading frame located upstream of the coding sequence (uORF). Moreover, its activity is inhibited by a PAS/LOV type photoreceptor, the action of which is counteracted by blue light. Consequently, this multi-level regulation of GGP would allow fine control of ascorbate synthesis. Indeed, experiments varying the expression of GGP have shown that it plays a central role in response to stress. This new understanding will be useful for developing varieties adapted to future environmental conditions.
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Ácido Ascórbico , Monoéster Fosfórico Hidrolasas , Ácido Ascórbico/biosíntesis , Ácido Ascórbico/metabolismo , Regulación de la Expresión Génica de las Plantas , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genéticaRESUMEN
Ascorbate (vitamin C) is one of the most abundant primary metabolites in plants. Its complex chemistry enables it to function as an antioxidant, as a free radical scavenger, and as a reductant for iron and copper. Ascorbate biosynthesis occurs via the mannose/l-galactose pathway in green plants, and the evidence for this pathway being the major route is reviewed. Ascorbate accumulation is leaves is responsive to light, reflecting various roles in photoprotection. GDP-l-galactose phosphorylase (GGP) is the first dedicated step in the pathway and is important in controlling ascorbate synthesis. Its expression is determined by a combination of transcription and translation. Translation is controlled by an upstream open reading frame (uORF) which blocks translation of the main GGP-coding sequence, possibly in an ascorbate-dependent manner. GGP associates with a PAS-LOV protein, inhibiting its activity, and dissociation is induced by blue light. While low ascorbate mutants are susceptible to oxidative stress, they grow nearly normally. In contrast, mutants lacking ascorbate do not grow unless rescued by supplementation. Further research should investigate possible basal functions of ascorbate in severely deficient plants involving prevention of iron overoxidation in 2-oxoglutarate-dependent dioxygenases and iron mobilization during seed development and germination.
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Ácido Ascórbico , Plantas , Ácido Ascórbico/metabolismo , Ácido Ascórbico/biosíntesis , Plantas/metabolismo , Plantas/genética , Regulación de la Expresión Génica de las Plantas , Vías BiosintéticasRESUMEN
This Special Issue was assembled to mark the 25th anniversary of the proposal of the d -mannose/ l -galactose (Smirnoff-Wheeler) ascorbate biosynthesis pathway in plants ( Wheeler et al., 1998 ). The issue aims to assess the current state of knowledge and to identify outstanding questions about ascorbate metabolism and functions in plants.
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Ácido Ascórbico , Plantas , Ácido Ascórbico/metabolismo , Plantas/metabolismoRESUMEN
l-Ascorbic acid (AsA, vitamin C) is a pivotal dietary nutrient with multifaceted importance in living organisms. In plants, the Smirnoff-Wheeler pathway is the primary route for AsA biosynthesis, and understanding the mechanistic details behind its component enzymes has implications for plant biology, nutritional science, and biotechnology. As part of an initiative to determine the structures of all six core enzymes of the pathway, the present study focuses on three of them in the model species Myrciaria dubia (camu-camu): GDP-d-mannose 3',5'-epimerase (GME), l-galactose dehydrogenase (l-GalDH), and l-galactono-1,4-lactone dehydrogenase (l-GalLDH). We provide insights into substrate and cofactor binding and the conformational changes they induce. The MdGME structure reveals a distorted substrate in the active site, pertinent to the catalytic mechanism. Mdl-GalDH shows that the way in which NAD+ association affects loop structure over the active site is not conserved when compared with its homologue in spinach. Finally, the structure of Mdl-GalLDH is described for the first time. This allows for the rationalization of previously identified residues which play important roles in the active site or in the formation of the covalent bond with FAD. In conclusion, this study enhances our understanding of AsA biosynthesis in plants, and the information provided should prove useful for biotechnological applications.
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Ácido Ascórbico , Frutas , Myrtaceae , Proteínas de Plantas , Ácido Ascórbico/metabolismo , Ácido Ascórbico/biosíntesis , Frutas/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/química , Myrtaceae/metabolismo , Myrtaceae/genética , Galactosa Deshidrogenasas/metabolismo , Galactosa Deshidrogenasas/genética , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/metabolismo , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/genéticaRESUMEN
Spatialization and analysis of the gross domestic product of second and tertiary industries (GDP23) can effectively depict the socioeconomic status of regional development. However, existing studies mainly conduct GDP spatialization using nighttime light data; few studies specifically concentrated on the spatialization and analysis of GDP23 in a built-up area by combining multi-source remote sensing images. In this study, the NPP-VIIRS-like dataset and Sentinel-2 multi-spectral remote sensing images in six years were combined to precisely spatialize and analyze the variation patterns of the GDP23 in the built-up area of Zibo city, China. Sentinel-2 images and the random forest (RF) classification method based on PIE-Engine cloud platform were employed to extract built-up areas, in which the NPP-VIIRS-like dataset and comprehensive nighttime light index were used to indicate the nighttime light magnitudes to construct models to spatialize GDP23 and analyze their change patterns during the study period. The results found that (1) the RF classification method can accurately extract the built-up area with an overall accuracy higher than 0.90; the change patterns of built-up areas varied among districts and counties, with Yiyuan county being the only administrative region with an annual expansion rate of more than 1%. (2) The comprehensive nighttime light index is a viable indicator of GDP23 in the built-up area; the fitted model exhibited an R2 value of 0.82, and the overall relative errors of simulated GDP23 and statistical GDP23 were below 1%. (3) The year 2018 marked a significant turning point in the trajectory of GDP23 development in the study area; in 2018, Zhoucun district had the largest decrease in GDP23 at -52.36%. (4) GDP23 gradation results found that Zhangdian district exhibited the highest proportion of high GDP23 (>9%), while the proportions of low GDP23 regions in the remaining seven districts and counties all exceeded 60%. The innovation of this study is that the GDP23 in built-up areas were first precisely spatialized and analyzed using the NPP-VIIRS-like dataset and Sentinel-2 images. The findings of this study can serve as references for formulating improved city planning strategies and sustainable development policies.
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This study utilized comprehensive graphical, descriptive and econometric methods to provide empirical answers to the nexus between government health expenditures and neonatal mortality in China. Secondary data from 2000 to 2021 was extracted from the World Development Indicators, after which it was analyzed empirically with the following results; in the past two decades, the incidence of neonatal death has reduced by 85%. Meanwhile, domestic general government health expenditure per capita ranged between $326.2 and $9.4 during the period with a mean value of $138. Average neonatal mortality rate recorded an approximately 10 deaths per 1000 live births, while government health expenditures and neonatal mortality showed a significant negative relationship in China. Therefore, this study confirms that China has been able to meet the SDG 3 with evidence indicating that this may be due to increased government health expenditure.
Cette étude a utilisé des méthodes graphiques, descriptives et économétriques complètes pour fournir des réponses empiriques au lien entre les dépenses publiques de santé et la mortalité néonatale en Chine. Les données secondaires de 2000 à 2021 ont été extraites des indicateurs de développement dans le monde, après quoi elles ont été analysées empiriquement avec les résultats suivants : au cours des deux dernières décennies, l'incidence des décès néonatals a diminué de 85 %. Dans le même temps, les dépenses de santé des administrations publiques nationales par habitant ont varié entre 326,2 et 9,4 dollars au cours de la période, avec une valeur moyenne de 138 dollars. Le taux de mortalité néonatale moyen a enregistré environ 10 décès pour 1 000 naissances vivantes, tandis que les dépenses publiques de santé et la mortalité néonatale ont montré une relation négative significative en Chine. Par conséquent, cette étude confirme que la Chine a été en mesure d'atteindre l'ODD 3 avec des preuves indiquant que cela pourrait être dû à l'augmentation des dépenses publiques de santé.
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Gastos en Salud , Mortalidad Infantil , Desarrollo Sostenible , Humanos , Gastos en Salud/estadística & datos numéricos , China/epidemiología , Mortalidad Infantil/tendencias , Recién Nacido , Lactante , Femenino , GobiernoRESUMEN
P2X7 receptors are nonselective cation channels that are activated by extracellular ATP and play important roles in inflammation. They differ from other P2X family members by a large intracellular C-terminus that mediates diverse signaling processes that are little understood. A recent cryo-EM study revealed that the C-terminus of the P2X7 receptor forms a unique cytoplasmic ballast domain that possesses a GDP-binding site as well as a dinuclear Zn2+ site. However, the molecular basis for the regulatory function of the ballast domain as well as the interplay between the various ligands remain unclear. Here, we successfully expressed a soluble trimeric P2X7 ballast domain (P2X7BD) and characterized its ligand binding properties using a biophysical approach. We identified calmodulin (CaM)-binding regions within the ballast domain and found that binding of Ca2+-CaM and GDP to P2X7BD have opposite effects on its stability. Small-angle X-ray scattering experiments indicate that Ca2+-CaM binding disrupts the trimeric state of P2X7BD. Our results provide a possible framework for the intracellular regulation of the P2X7 receptor.
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Calmodulina , Receptores Purinérgicos P2X7 , Calmodulina/metabolismo , Receptores Purinérgicos P2X7/genética , Receptores Purinérgicos P2X7/metabolismo , Unión Proteica , Sitios de Unión , Dominios ProteicosRESUMEN
Mutations in the SLC35C1 gene encoding the Golgi GDP-fucose transporter are known to cause leukocyte adhesion deficiency II. However, improvement of fucosylation in leukocyte adhesion deficiency II patients treated with exogenous fucose suggests the existence of an SLC35C1-independent route of GDP-fucose transport, which remains a mystery. To investigate this phenomenon, we developed and characterized a human cell-based model deficient in SLC35C1 activity. The resulting cells were cultured in the presence/absence of exogenous fucose and mannose, followed by examination of fucosylation potential and nucleotide sugar levels. We found that cells displayed low but detectable levels of fucosylation in the absence of SLC35C1. Strikingly, we show that defects in fucosylation were almost completely reversed upon treatment with millimolar concentrations of fucose. Furthermore, we show that even if fucose was supplemented at nanomolar concentrations, it was still incorporated into glycans by these knockout cells. We also found that the SLC35C1-independent transport preferentially utilized GDP-fucose from the salvage pathway over the de novo biogenesis pathway as a source of this substrate. Taken together, our results imply that the Golgi systems of GDP-fucose transport discriminate between substrate pools obtained from different metabolic pathways, which suggests a functional connection between nucleotide sugar transporters and nucleotide sugar synthases.
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Fucosa , Guanosina Difosfato Fucosa , Síndrome de Deficiencia de Adhesión del Leucocito/terapia , Fucosa/metabolismo , Aparato de Golgi/metabolismo , Guanosina Difosfato Fucosa/metabolismo , Humanos , Proteínas de Transporte de Membrana/metabolismo , Proteínas de Transporte de Monosacáridos/genética , Proteínas de Transporte de Monosacáridos/metabolismo , Polisacáridos/metabolismoRESUMEN
Leukocyte adhesion deficiency (LAD) is an immunodeficiency caused by defects in the adhesion of leukocytes (especially neutrophils) to the blood vessel wall. As a result, patients with LAD suffer from severe bacterial infections and impaired wound healing, accompanied by neutrophilia. In LAD-I, characterized directly after birth by delayed separation of the umbilical cord, mutations are found in ITGB2, the gene that encodes the ß subunit (CD18) of the ß2 integrins. In the rare LAD-II disease, the fucosylation of selectin ligands is disturbed, caused by mutations in SLC35C1, the gene that encodes a GDP-fucose transporter of the Golgi system. LAD-II patients lack the H and Lewis Lea and Leb blood group antigens. Finally, in LAD-III, the conformational activation of the hematopoietically expressed ß integrins is disturbed, leading to leukocyte and platelet dysfunction. This last syndrome is caused by mutations in FERMT3, encoding the kindlin-3 protein in all blood cells, involved in the regulation of ß integrin conformation. This article contains an update of the mutations that we consider to be relevant for the various forms of LAD.
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Síndrome de Deficiencia de Adhesión del Leucocito , Humanos , Adhesión Celular/genética , Síndrome de Deficiencia de Adhesión del Leucocito/genética , Antígenos CD18/genética , Antígenos CD18/metabolismo , Leucocitos , MutaciónRESUMEN
BACKGROUND: LFucose is a rare sugar that has beneficial biological activities, and its industrial production is mainly achieved with brown algae through acidic/enzymatic fucoidan hydrolysis and a cumbersome purification process. Fucoidan is synthesized through the condensation of a key substance, guanosine 5'diphosphate (GDP)Lfucose. Therefore, a more direct approach for biomanufacturing Lfucose could be the enzymatic degradation of GDPLfucose. However, no native enzyme is known to efficiently catalyze this reaction. Therefore, it would be a feasible solution to engineering an enzyme with similar function to hydrolyze GDPLfucose. RESULTS: Herein, we constructed a de novo Lfucose synthetic route in Bacillus subtilis by introducing heterologous GDPLfucose synthesis pathway and engineering GDPmannose mannosyl hydrolase (WcaH). WcaH displays a high binding affinity but low catalytic activity for GDPLfucose, therefore, a substrate simulationbased structural analysis of the catalytic center was employed for the rational design and mutagenesis of selected positions on WcaH to enhance its GDPLfucosesplitting efficiency. Enzyme mutants were evaluated in vivo by inserting them into an artificial metabolic pathway that enabled B. subtilis to yield Lfucose. WcaHR36Y/N38R was found to produce 1.6 g/L Lfucose during shakeflask growth, which was 67.3% higher than that achieved by wildtype WcaH. The accumulated Lfucose concentration in a 5 L bioreactor reached 6.4 g/L. CONCLUSIONS: In this study, we established a novel microbial engineering platform for the fermentation production of Lfucose. Additionally, we found an efficient GDPmannose mannosyl hydrolase mutant for Lfucose biosynthesis that directly hydrolyzes GDPLfucose. The engineered strain system established in this study is expected to provide new solutions for Lfucose or its high valueadded derivatives production.
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Hidrolasas , Manosa , Hidrolasas/metabolismo , Manosa/metabolismo , Fucosa/metabolismo , Bacillus subtilis/genética , Reactores Biológicos , Fermentación , Ingeniería MetabólicaRESUMEN
Cell division control protein 42 homolog (Cdc42), which controls a variety of cellular functions including rearrangements of the cell cytoskeleton, cell differentiation and proliferation, is a potential cancer therapeutic target. As an endogenous negative regulator of Cdc42, the Rho GDP dissociation inhibitor 1 (RhoGDI1) can prevent the GDP/GTP exchange of Cdc42 to maintain Cdc42 into an inactive state. To investigate the inhibition mechanism of Cdc42 through RhoGDI1 at the atomic level, we performed molecular dynamics (MD) simulations. Without RhoGDI1, Cdc42 has more flexible conformations, especially in switch regions which are vital for binding GDP/GTP and regulators. In the presence of RhoGDI1, it not only can change the intramolecular interactions of Cdc42 but also can maintain the switch regions into a closed conformation through extensive interactions with Cdc42. These results which are consistent with findings of biochemical and mutational studies provide deep structural insights into the inhibition mechanisms of Cdc42 by RhoGDI1. These findings are beneficial for the development of novel therapies targeting Cdc42-related cancers.
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Simulación de Dinámica Molecular , Inhibidor alfa de Disociación del Nucleótido Guanina rho , Proteína de Unión al GTP cdc42 , Diferenciación Celular , Guanosina TrifosfatoRESUMEN
Heterotrimeric guanine nucleotide-binding proteins (G proteins) are composed of α, ß, and γ subunits, and Gα has a GDP/GTP-binding pocket. When a guanine nucleotide exchange factor (GEF) interacts with Gα, GDP is released, and GTP interacts to Gα. The GTP-bound activated Gα dissociates from GEF and Gßγ, mediating the induction of various intracellular signaling pathways. Depending on the sequence similarity and cellular function, Gα subunits are subcategorized into four subfamilies: Gαi/o, Gαs, Gαq/11, and Gα12/13. Although the Gαi/o subtype family proteins, Gαi3 and GαoA, share similar sequences and functions, they differ in their GDP/GTP turnover profiles, with GαoA possessing faster rates than Gαi3. The structural factors responsible for these differences remain unknown. In this study, we employed hydrogen/deuterium exchange mass spectrometry and mutational studies to investigate the factors responsible for these functional differences. The Gα subunit consists of a Ras-like domain (RD) and an α-helical domain (AHD). The RD has GTPase activity and receptor-binding and effector-binding regions; however, the function of the AHD has not yet been extensively studied. In this study, the chimeric construct containing the RD of Gαi3 and the AHD of GαoA showed a GDP/GTP turnover profile similar to that of GαoA, suggesting that the AHD is the major regulator of the GDP/GTP turnover profile. Additionally, site-directed mutagenesis revealed the importance of the N-terminal part of αA and αA/αB loops in the AHD for the GDP/GTP exchange. These results suggest that the AHD regulates the nucleotide exchange rate within the Gα subfamily.
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Subunidades alfa de la Proteína de Unión al GTP Gi-Go , Proteínas de Unión al GTP Heterotriméricas , Subunidades alfa de la Proteína de Unión al GTP Gi-Go/metabolismo , Factores de Intercambio de Guanina Nucleótido/genética , Factores de Intercambio de Guanina Nucleótido/metabolismo , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Proteínas de Unión al GTP Heterotriméricas/metabolismoRESUMEN
The KEOPS complex is an evolutionarily conserved protein complex in all three domains of life (Bacteria, Archaea, and Eukarya). In budding yeast Saccharomyces cerevisiae, the KEOPS complex (ScKEOPS) consists of five subunits, which are Kae1, Bud32, Cgi121, Pcc1, and Gon7. The KEOPS complex is an ATPase and is required for tRNA N6-threonylcarbamoyladenosine modification, telomere length maintenance, and efficient DNA repair. Here, recombinant ScKEOPS full complex and Kae1-Pcc1-Gon7 and Bud32-Cgi121 subcomplexes were purified and their biochemical activities were examined. KEOPS was observed to have ATPase and GTPase activities, which are predominantly attributed to the Bud32 subunit, as catalytically dead Bud32, but not catalytically dead Kae1, largely eliminated the ATPase/GTPase activity of KEOPS. In addition, KEOPS could hydrolyze ADP to adenosine or GDP to guanosine, and produce PPi, indicating that KEOPS is an ADP/GDP nucleotidase. Further mutagenesis characterization of Bud32 and Kae1 subunits revealed that Kae1, but not Bud32, is responsible for the ADP/GDP nucleotidase activity. In addition, the Kae1V309D mutant exhibited decreased ADP/GDP nucleotidase activity in vitro and shortened telomeres in vivo, but showed only a limited defect in t6A modification, suggesting that the ADP/GDP nucleotidase activity of KEOPS contributes to telomere length regulation.
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Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Adenosina Trifosfatasas/metabolismo , Adenosina Difosfato/metabolismo , GTP Fosfohidrolasas/metabolismoRESUMEN
This study examines the effects of long-run civil wars on healthcare, which is an important component of human capital development and their causality nexus in Afghanistan using the MVAR (modified vector autoregressive) approach and the Granger non-causality model covering data period 2002Q3-2020Q4. The primary results support a significant long-run relationship between variables, while the results of the MVAR model indicate the per capita cost of war, per capita GDP, and age dependency ratio have significantly positive impacts on per capita health expenditures, whereas child mortality rate and crude death rate have negative impacts. The results of the Granger non-causality approach demonstrate that there is a statistically significant bidirectional causality nexus between per capita health expenditure, per capita cost of war, per capita GDP, child mortality rate, crude death rate, and age dependency ratio, while it also supports the existence of strong and significant interconnectivity and multidimensionality between per capita cost of war and per capita health expenditure, with a significantly strong feedback response from the control variables. Important policy implications sourced from the key findings are also discussed.
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Mortalidad del Niño , Gastos en Salud , Niño , Humanos , Afganistán , Causalidad , Conflictos ArmadosRESUMEN
AIM: In view of the long-standing recognition that gross domestic product (GDP) does not capture the unremunerated work largely conducted by women upon which societal well-being depends, to discuss the implications for GDP of maternal, newborn, child and adolescent health (MNCAH), and its influences on health, well-being and prosperity across the life course and across generations. METHODS: A wide-ranging discussion of the informal think-tank The Venice Forum was held over two days, with inputs from invited experts in person and online. RESULTS: There was consensus that a strong case could be made for inclusion of unremunerated work largely conducted by women as a positive contribution to GDP in view of its impact on future health and prosperity, and conversely exclusion from GDP of outputs from industries which harm health. CONCLUSION: Taken with the current challenges from COVID, climate change and conflict, there is a compelling need to redefine economic progress through equitable models and metrics that incorporate short-/medium-/long-term societal value of activities that improve MNCAH.