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1.
Yakugaku Zasshi ; 140(10): 1199-1206, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32999198

RESUMO

Potential risks to the fetus or infant should be considered prior to medication during pregnancy and lactation. It is essential to evaluate the exposure levels of drugs and their related factors in addition to toxicological effects. Epilepsy is one of the most common neurological complications in pregnancy; some women continue to use antiepileptic drugs (AEDs) to control seizures. Benzodiazepines (BZDs) are widely prescribed for several women who experience symptoms such as anxiety and insomnia during the postpartum period. In this review, we describe the 1) transport mechanisms of AEDs across the placenta and the effects of these drugs on placental transporters, and 2) the transfer of BZDs into breast milk. Our findings indicated that carrier systems were involved in the uptake of gabapentin (GBP) and lamotrigine (LTG) in placental trophoblast cell lines. SLC7A5 was the main contributor to GBP transport in placental cells. LTG was transported by a carrier that was sensitive to chloroquine, imipramine, quinidine, and verapamil. Short-term exposure to 16 AEDs had no effect on folic acid uptake in placental cells. However, long-term exposure to valproic acid (VPA) affected the expression of folate carriers (FOLR1, SLC46A1). Furthermore, VPA administration changed the expression levels of various transporters in rat placenta, suggesting that sensitivity to VPA differed across gestational stages. Lastly, we developed a method for quantifying eight BZDs in human breast milk and plasma using LC/MS/MS, and successfully applied it to quantify alprazolam in breast milk and plasma donated by a lactating woman.


Assuntos
Anticonvulsivantes/metabolismo , Benzodiazepinas/metabolismo , Transporte Biológico/genética , Aleitamento Materno , Gabapentina/metabolismo , Lactação/metabolismo , Lamotrigina/metabolismo , Transportador 1 de Aminoácidos Neutros Grandes/fisiologia , Troca Materno-Fetal , Leite Humano/metabolismo , Placenta/metabolismo , Ácido Valproico/metabolismo , Anticonvulsivantes/efeitos adversos , Benzodiazepinas/efeitos adversos , Benzodiazepinas/uso terapêutico , Linhagem Celular , Epilepsia/tratamento farmacológico , Feminino , Receptor 1 de Folato/genética , Receptor 1 de Folato/metabolismo , Gabapentina/efeitos adversos , Expressão Gênica/efeitos dos fármacos , Humanos , Lamotrigina/efeitos adversos , Gravidez , Complicações na Gravidez/tratamento farmacológico , Transportador de Folato Acoplado a Próton/genética , Transportador de Folato Acoplado a Próton/metabolismo , Ácido Valproico/efeitos adversos
2.
Nat Commun ; 11(1): 4055, 2020 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-32792504

RESUMO

Although metastasis is the most common cause of cancer deaths, metastasis-intrinsic dependencies remain largely uncharacterized. We previously reported that metastatic pancreatic cancers were dependent on the glucose-metabolizing enzyme phosphogluconate dehydrogenase (PGD). Surprisingly, PGD catalysis was constitutively elevated without activating mutations, suggesting a non-genetic basis for enhanced activity. Here we report a metabolic adaptation that stably activates PGD to reprogram metastatic chromatin. High PGD catalysis prevents transcriptional up-regulation of thioredoxin-interacting protein (TXNIP), a gene that negatively regulates glucose import. This allows glucose consumption rates to rise in support of PGD, while simultaneously facilitating epigenetic reprogramming through a glucose-fueled histone hyperacetylation pathway. Restoring TXNIP normalizes glucose consumption, lowers PGD catalysis, reverses hyperacetylation, represses malignant transcripts, and impairs metastatic tumorigenesis. We propose that PGD-driven suppression of TXNIP allows pancreatic cancers to avidly consume glucose. This renders PGD constitutively activated and enables metaboloepigenetic selection of additional traits that increase fitness along glucose-replete metastatic routes.


Assuntos
Cromatina/metabolismo , Glucose/metabolismo , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Animais , Transporte Biológico/genética , Transporte Biológico/fisiologia , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Reprogramação Celular/genética , Reprogramação Celular/fisiologia , Imunoprecipitação da Cromatina , Epigênese Genética/genética , Camundongos , Camundongos Nus , Neoplasias Pancreáticas/genética , Fosfogluconato Desidrogenase/genética , Fosfogluconato Desidrogenase/metabolismo , Tiorredoxinas/genética , Tiorredoxinas/metabolismo
3.
PLoS Genet ; 16(8): e1008966, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776922

RESUMO

The vacuole of the yeast Saccharomyces cerevisiae plays an important role in nutrient storage. Arginine, in particular, accumulates in the vacuole of nitrogen-replete cells and is mobilized to the cytosol under nitrogen starvation. The arginine import and export systems involved remain poorly characterized, however. Furthermore, how their activity is coordinated by nitrogen remains unknown. Here we characterize Vsb1 as a novel vacuolar membrane protein of the APC (amino acid-polyamine-organocation) transporter superfamily which, in nitrogen-replete cells, is essential to active uptake and storage of arginine into the vacuole. A shift to nitrogen starvation causes apparent inhibition of Vsb1-dependent activity and mobilization of stored vacuolar arginine to the cytosol. We further show that this arginine export involves Ypq2, a vacuolar protein homologous to the human lysosomal cationic amino acid exporter PQLC2 and whose activity is detected only in nitrogen-starved cells. Our study unravels the main arginine import and export systems of the yeast vacuole and suggests that they are inversely regulated by nitrogen.


Assuntos
Arginina/metabolismo , Nitrogênio/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Aminoácidos/genética , Transporte Biológico/genética , Humanos , Membranas Intracelulares/metabolismo , Lisossomos/genética , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Saccharomyces cerevisiae/metabolismo , Vacúolos/genética , Vacúolos/metabolismo
4.
Int J Food Microbiol ; 330: 108783, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-32659523

RESUMO

The contamination of Aspergillus carbonarius causes decreases and great decay of agricultural products, and threatens the human and animal health by producing mycotoxins, especially ochratoxin A. Bacillus subtilis has been proved to efficiently inhibit the growth of A. carbonarius. Revealing the major active compound and the mechanisms for the antifungal of B. subtilis are essential to enhance its antifungal activity and control the quality of antifungal products made of it. In this study, we determined that iturin A is the major compound that inhibits Aspergillus carbonarius, a widespread fungal pathogen of grape and other fruits. Iturin A significantly inhibited growth and ochratoxin A production of A. carbonarius with minimal inhibitory concentrations (MICs) of 10 µg/mL and 0.312 µg/mL, respectively. Morphological observations revealed that iturin A caused swelling of the fungal cells and thinning of the cell wall and membrane at 1/2 MIC, whereas it inhibited fungal spore germination and caused mitochondrial swelling at higher concentrations. A differential transcriptomic analysis indicated that the mechanisms used by iturin A to inhibit A. carbonarius were to downregulate the expression of genes related to cell membrane, transport, osmotic pressure, oxidation-reduction processes, and energy metabolism. Among the down-regulated genes, those related to the transport capacity were most significantly influenced, including the increase of energy-related transport pathways and decrease of other pathways. Notably, the genes related to taurine and hypotaurine metabolism were also decreased, indicating iturin A potentially cause the occurrence of osmotic imbalance in A. carbonarius, which may be the intrinsic cause for the swelling of fungal cells and mitochondria. Overall, iturin A produced by B. subtilis played important roles to inhibit A. carbonarius via changing the fungal cell structure and causing perturbations to energy, transport and osmotic pressure metabolisms in fungi. The results indicated a new direction for researches on the mechanisms for lipopeptides and provided useful information to develop more efficient antifungal agents, which are important to agriculture and biomedicine.


Assuntos
Antifúngicos/farmacologia , Aspergillus/efeitos dos fármacos , Aspergillus/metabolismo , Bacillus subtilis/metabolismo , Peptídeos Cíclicos/farmacologia , Antifúngicos/metabolismo , Aspergillus/genética , Aspergillus/crescimento & desenvolvimento , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/genética , Metabolismo Energético/efeitos dos fármacos , Metabolismo Energético/genética , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Micotoxinas/metabolismo , Pressão Osmótica/efeitos dos fármacos , Peptídeos Cíclicos/metabolismo , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/metabolismo , Transcriptoma
5.
Am J Physiol Cell Physiol ; 319(2): C359-C370, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32520610

RESUMO

SLC4A11 is the only member of the SLC4 family that transports protons rather than bicarbonate. SLC4A11 is expressed in corneal endothelial cells, and its mutation causes corneal endothelial dystrophy, although the mechanism of pathogenesis is unknown. We previously demonstrated that the magnitude of the H+ conductance (Gm) mediated by SLC4A11 is increased by rises in intracellular as well as extracellular pH (pHi and pHe). To better understand this feature and whether it is altered in disease, we studied the pH dependence of wild-type and mutant mouse Slc4a11 expressed in Xenopus oocytes. Using voltage-clamp circuitry in conjunction with a H+-selective microelectrode and a microinjector loaded with NaHCO3, we caused incremental rises in oocyte pHi and measured the effect on Gm. We find that the rise of Gm has a steeper pHi dependence at pHe =8.50 than at pHe =7.50. Data gathered at pHe =8.50 can be fit to the Hill equation enabling the calculation of a pK value that reports pHi dependence. We find that mutation of lysine residues that are close to the first transmembrane span (TM1) causes an alkaline shift in pK. Furthermore, two corneal-dystrophy-causing mutations close to the extracellular end of TM1, E399K and T401K (E368K and T370K in mouse), cause an acidic shift in pK, while a third mutation in the fourth intracellular loop, R804H (R774H in mouse), causes an alkaline shift in pK. This is the first description of determinants of SLC4A11 pH dependence and the first indication that a shift in pH dependence could modify disease expressivity in some cases of corneal dystrophy.


Assuntos
Proteínas de Transporte de Ânions/genética , Transporte Biológico/genética , Distrofias Hereditárias da Córnea/genética , Lisina/genética , Simportadores/genética , Animais , Animais Geneticamente Modificados/genética , Animais Geneticamente Modificados/metabolismo , Bicarbonatos/metabolismo , Distrofias Hereditárias da Córnea/metabolismo , Distrofias Hereditárias da Córnea/patologia , Modelos Animais de Doenças , Epitélio Posterior/metabolismo , Epitélio Posterior/patologia , Regulação da Expressão Gênica/genética , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Transporte de Íons/genética , Lisina/metabolismo , Camundongos , Mutação/genética , Oócitos/metabolismo , Oócitos/patologia , Sódio , Xenopus/genética
6.
Appl Environ Microbiol ; 86(16)2020 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-32503905

RESUMO

The purple nonsulfur bacterium Rhodopseudomonas palustris TIE-1 can produce useful biochemicals such as bioplastics and biobutanol. Production of such biochemicals requires intracellular electron availability, which is governed by the availability and the transport of essential metals such as iron (Fe). Because of the distinct chemical properties of ferrous [Fe(II)] and ferric iron [Fe(III)], different systems are required for their transport and storage in bacteria. Although Fe(III) transport systems are well characterized, we know much less about Fe(II) transport systems except for the FeoAB system. Iron transporters can also import manganese (Mn). We studied Fe and Mn transport by five putative Fe transporters in TIE-1 under metal-replete, metal-depleted, oxic, and anoxic conditions. We observed that by overexpressing feoAB, efeU, and nramp1AB, the intracellular concentrations of Fe and Mn can be enhanced in TIE-1 under oxic and anoxic conditions, respectively. The deletion of a single gene/operon does not attenuate Fe or Mn uptake in TIE-1 regardless of the growth conditions used. This indicates that genetically dissimilar yet functionally redundant Fe transporters in TIE-1 can complement each other. Relative gene expression analysis shows that feoAB and efeU are expressed during Fe and Mn depletion under both oxic and anoxic conditions. The promoters of these transporter genes contain a combination of Fur and Fnr boxes, suggesting that their expression is regulated by both Fe and oxygen availability. The findings from this study will help us modulate intracellular Fe and Mn concentrations, ultimately improving TIE-1's ability to produce desirable biomolecules.IMPORTANCE Rhodopseudomonas palustris TIE-1 is a metabolically versatile bacterium that can use various electron donors, including Fe(II) and poised electrodes, for photoautotrophic growth. TIE-1 can produce useful biomolecules, such as biofuels and bioplastics, under various growth conditions. Production of such reduced biomolecules is controlled by intracellular electron availability, which, in turn, is mediated by various iron-containing proteins in the cell. Several putative Fe transporters exist in TIE-1's genome. Some of these transporters can also transport Mn, part of several important cellular enzymes. Therefore, understanding the ability to transport and respond to various levels of Fe and Mn under different conditions is important to improve TIE-1's ability to produce useful biomolecules. Our data suggest that by overexpressing Fe transporter genes via plasmid-based expression, we can increase the import of Fe and Mn in TIE-1. Future work will leverage these data to improve TIE-1 as an attractive microbial chassis and future biotechnological workhorse.


Assuntos
Proteínas de Bactérias/genética , Ferro/metabolismo , Manganês/metabolismo , Proteínas de Membrana Transportadoras/genética , Família Multigênica , Rodopseudomonas/genética , Proteínas de Bactérias/metabolismo , Transporte Biológico/genética , Proteínas de Membrana Transportadoras/metabolismo , Rodopseudomonas/metabolismo
7.
PLoS One ; 15(5): e0226453, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32379825

RESUMO

Membrane transporters carry key metabolites across the cell membrane and, from a resource standpoint, are hypothesized to be produced when necessary. The expression of membrane transporters in metabolic pathways is often upregulated by the transporter substrate. In E. coli, such systems include for example the lacY, araFGH, and xylFGH genes, which encode for lactose, arabinose, and xylose transporters, respectively. As a case study of a minimal system, we build a generalizable physical model of the xapABR genetic circuit, which features a regulatory feedback loop via membrane transport (positive feedback) and enzymatic degradation (negative feedback) of an inducer. Dynamical systems analysis and stochastic simulations show that the membrane transport makes the model system bistable in certain parameter regimes. Thus, it serves as a genetic "on-off" switch, enabling the cell to only produce a set of metabolic enzymes when the corresponding metabolite is present in large amounts. We find that the negative feedback from the degradation enzyme does not significantly disturb the positive feedback from the membrane transporter. We investigate hysteresis in the switching and discuss the role of cooperativity and multiple binding sites in the model circuit. Fundamentally, this work explores how a stable genetic switch for a set of enzymes is obtained from transcriptional auto-activation of a membrane transporter through its substrate.


Assuntos
Adaptação Fisiológica/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Redes Reguladoras de Genes , Genes de Troca , Modelos Biológicos , Sítios de Ligação , Transporte Biológico/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Retroalimentação Fisiológica , Regulação Bacteriana da Expressão Gênica , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Pentosiltransferases/genética , Pentosiltransferases/metabolismo , Regiões Promotoras Genéticas , RNA Mensageiro/metabolismo , Ribonucleosídeos/metabolismo , Processos Estocásticos , Transativadores/genética , Transativadores/metabolismo , Transcrição Genética
8.
PLoS Genet ; 16(5): e1008763, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32384077

RESUMO

The ACK family tyrosine kinase SID-3 is involved in the endocytic uptake of double-stranded RNA. Here we identified SID-3 as a previously unappreciated recycling regulator in the Caenorhabditis elegans intestine. The RAB-10 effector EHBP-1 is required for the endosomal localization of SID-3. Accordingly, animals with loss of SID-3 phenocopied the recycling defects observed in ehbp-1 and rab-10 single mutants. Moreover, we detected sequential protein interactions between EHBP-1, SID-3, NCK-1, and DYN-1. In the absence of SID-3, DYN-1 failed to localize at tubular recycling endosomes, and membrane tubules breaking away from endosomes were mostly absent, suggesting that SID-3 acts synergistically with the downstream DYN-1 to promote endosomal tubule fission. In agreement with these observations, overexpression of DYN-1 significantly increased recycling transport in SID-3-deficient cells. Finally, we noticed that loss of RAB-10 or EHBP-1 compromised feeding RNAi efficiency in multiple tissues, implicating basolateral recycling in the transport of RNA silencing signals. Taken together, our study demonstrated that in C. elegans intestinal epithelia, SID-3 acts downstream of EHBP-1 to direct fission of recycling endosomal tubules in concert with NCK-1 and DYN-1.


Assuntos
Proteínas de Caenorhabditis elegans/fisiologia , Citocinese/genética , Dinaminas/fisiologia , Endocitose/fisiologia , Endossomos/metabolismo , Proteínas Tirosina Quinases/fisiologia , Proteínas de Transporte Vesicular/fisiologia , Animais , Animais Geneticamente Modificados , Transporte Biológico/genética , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Endocitose/genética , Estudo de Associação Genômica Ampla , Transdução de Sinais/genética , Proteínas rab de Ligação ao GTP/metabolismo
9.
Proc Natl Acad Sci U S A ; 117(18): 9857-9864, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32300017

RESUMO

Vitamin A has diverse biological functions and is essential for human survival at every point from embryogenesis to adulthood. Vitamin A and its derivatives have been used to treat human diseases including vision diseases, skin diseases, and cancer. Both insufficient and excessive vitamin A uptake are detrimental, but how its transport is regulated is poorly understood. STRA6 is a multitransmembrane domain cell-surface receptor and mediates vitamin A uptake from plasma retinol binding protein (RBP). STRA6 can mediate both cellular vitamin A influx and efflux, but what regulates these opposing activities is unknown. To answer this question, we purified and identified STRA6-associated proteins in a native mammalian cell type that takes up vitamin A through STRA6 using mass spectrometry. We found that the major protein repeatedly identified as STRA6-associated protein is calmodulin, consistent with the cryogenic electron microscopy (cryo-EM) study of zebrafish STRA6 associated with calmodulin. Using radioactivity-based, high-performance liquid chromatography (HPLC)-based and real-time fluorescence techniques, we found that calmodulin profoundly affects STRA6's vitamin A transport activity. Increased calcium/calmodulin promotes cellular vitamin A efflux and suppresses vitamin A influx through STRA6. Further mechanistic studies revealed that calmodulin enhances the binding of apo-RBP to STRA6, and this enhancement is much more pronounced for apo-RBP than holo-RBP. This study revealed that calmodulin regulates STRA6's vitamin A influx or efflux activity by modulating its preferential interaction with apo-RBP or holo-RBP. This molecular mechanism of regulating vitamin A transport may point to new directions to treat human diseases associated with insufficient or excessive vitamin A uptake.


Assuntos
Transporte Biológico/genética , Calmodulina/genética , Proteínas de Membrana/genética , Proteínas Plasmáticas de Ligação ao Retinol/genética , Vitamina A/metabolismo , Animais , Apoproteínas/genética , Apoproteínas/metabolismo , Cálcio/metabolismo , Bovinos , Linhagem Celular , Cromatografia Líquida de Alta Pressão , Microscopia Crioeletrônica , Humanos , Proteínas de Membrana/metabolismo , Ligação Proteica/genética , Receptores de Superfície Celular/genética , Proteínas Plasmáticas de Ligação ao Retinol/metabolismo , Vitamina A/genética , Peixe-Zebra/genética
10.
BMC Plant Biol ; 20(1): 133, 2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32234010

RESUMO

BACKGROUND: Genes associated with arsenite uptake and transport in rice plants (i.e., OsLsi1, OsLsi2, OsLsi3, OsLsi6 and OsABCC1) have been identified to date. However, their expression over time during the whole growth period of rice under arsenite stress conditions is still poorly understood. In this study, the dynamics of gene expression associated with arsenite transport and arsenic concentrations in different organs of rice were investigated to determine the critical period(s) of arsenite uptake and translocation regulated by gene expression during the whole growth period. RESULTS: The relative expression of OsLsi2 and OsLsi1 in the roots was upregulated and reached its highest value (2-∆∆Ct = 4.04 and 1.19, respectively) at the jointing stage (9 weeks after transplantation), in which the arsenic concentration in roots also was the highest at 144 mg/kg. A range from 45.1 to 61.2% of total arsenic accumulated in the roots during seedling to heading stages (3-16 weeks), which was mainly associated with the relatively high expression of OsABCC1 (1.50-7.68), resulting in arsenic located in the vacuoles of roots. Subsequently, the As translocation factor from root to shoot increased over time from heading to milky ripe (16-20 weeks), and 74.3% of the arsenic accumulated in shoots at the milk stage. Such an increase in arsenic accumulation in shoots was likely related to the findings that (i) OsABCC1 expression in roots was suppressed to 0.14-0.75 in 18-20 weeks; (ii) OsLsi3 and OsABCC1 expression in nodes I, II, and III was upregulated to 4.01-25.8 and 1.59-2.36, respectively, in 16-20 weeks; and (iii) OsLsi6 and OsABCC1 expression in leaves and husks was significantly upregulated to 2.03-5.26 at 18 weeks. CONCLUSIONS: The jointing stage is the key period for the expression of arsenite-transporting genes in roots, and the heading to milky ripe stages are the key period for the expression of arsenite-transporting genes in shoots, both of which should be considered for regulation during safe rice production in arsenic-contaminated paddy soil.


Assuntos
Arsênico/metabolismo , Arsenitos/metabolismo , Expressão Gênica/efeitos dos fármacos , Oryza/metabolismo , Arsênico/toxicidade , Arsenitos/toxicidade , Transporte Biológico/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Oryza/genética , Oryza/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/metabolismo , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade
11.
Proc Natl Acad Sci U S A ; 117(18): 10067-10078, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32321831

RESUMO

Disorders of oxygen transport are commonly attributed to inadequate carrying capacity (anemia) but may also relate to inefficient gas exchange by red blood cells (RBCs), a process that is poorly characterized yet assumed to be rapid. Without direct measurements of gas exchange at the single-cell level, the barriers to O2 transport and their relationship with hematological disorders remain ill defined. We developed a method to track the flow of O2 in individual RBCs by combining ultrarapid solution switching (to manipulate gas tension) with single-cell O2 saturation fluorescence microscopy. O2 unloading from RBCs was considerably slower than previously estimated in acellular hemoglobin solutions, indicating the presence of diffusional barriers in intact cells. Rate-limiting diffusion across cytoplasm was demonstrated by osmotically induced changes to hemoglobin concentration (i.e., diffusive tortuosity) and cell size (i.e., diffusion pathlength) and by comparing wild-type cells with hemoglobin H (HbH) thalassemia (shorter pathlength and reduced tortuosity) and hereditary spherocytosis (HS; expanded pathlength). Analysis of the distribution of O2 unloading rates in HS RBCs identified a subpopulation of spherocytes with greatly impaired gas exchange. Tortuosity imposed by hemoglobin was verified by demonstrating restricted diffusivity of CO2, an acidic gas, from the dissipative spread of photolytically uncaged H+ ions across cytoplasm. Our findings indicate that cytoplasmic diffusion, determined by pathlength and tortuosity, is a major barrier to efficient gas handling by RBCs. Consequently, changes in RBC shape and hemoglobin concentration, which are common manifestations of hematological disorders, can have hitherto unrecognized and clinically significant implications on gas exchange.


Assuntos
Transporte Biológico/genética , Eritrócitos/metabolismo , Gases/sangue , Oxigênio/sangue , Adulto , Idoso , Dióxido de Carbono/sangue , Citoplasma/metabolismo , Feminino , Voluntários Saudáveis , Hemoglobinas/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Célula Única
12.
Biochim Biophys Acta Gen Subj ; 1864(7): 129581, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32114025

RESUMO

BACKGROUND: In Gram-negative bacteria, type Va and Vc autotransporters are proteins that contain both a secreted virulence factor (the "passenger" domain) and a ß-barrel that aids its export. While it is known that the folding and insertion of the ß-barrel domain utilize the ß-barrel assembly machinery (BAM) complex, how the passenger domain is secreted and folded across the membrane remains to be determined. The hairpin model states that passenger domain secretion occurs independently through the fully-formed and membrane-inserted ß-barrel domain via a hairpin folding intermediate. In contrast, the BamA-assisted model states that the passenger domain is secreted through a hybrid of BamA, the essential subunit of the BAM complex, and the ß-barrel domain of the autotransporter. METHODS: To ascertain the models' plausibility, we have used molecular dynamics to simulate passenger domain secretion for two autotransporters, EspP and YadA. RESULTS: We observed that each protein's ß-barrel is unable to accommodate the secreting passenger domain in a hairpin configuration without major structural distortions. Additionally, the force required for secretion through EspP's ß-barrel is more than that through the BamA ß-barrel. CONCLUSIONS: Secretion of autotransporters most likely occurs through an incompletely formed ß-barrel domain of the autotransporter in conjunction with BamA. GENERAL SIGNIFICANCE: Secretion of virulence factors is a process used by practically all pathogenic Gram-negative bacteria. Understanding this process is a necessary step towards limiting their infectious capacity.


Assuntos
Proteínas da Membrana Bacteriana Externa/genética , Proteínas de Escherichia coli/genética , Modelos Moleculares , Dobramento de Proteína , Sistemas de Secreção Tipo V/genética , Proteínas da Membrana Bacteriana Externa/ultraestrutura , Transporte Biológico/genética , Escherichia coli/genética , Escherichia coli/ultraestrutura , Proteínas de Escherichia coli/ultraestrutura , Humanos , Serina Endopeptidases/genética , Serina Endopeptidases/ultraestrutura
13.
Nat Chem Biol ; 16(4): 469-478, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32152546

RESUMO

Solute carriers (SLCs) are the largest family of transmembrane transporters in humans and are major determinants of cellular metabolism. Several SLCs have been shown to be required for the uptake of chemical compounds into cellular systems, but systematic surveys of transporter-drug relationships in human cells are currently lacking. We performed a series of genetic screens in a haploid human cell line against 60 cytotoxic compounds representative of the chemical space populated by approved drugs. By using an SLC-focused CRISPR-Cas9 library, we identified transporters whose absence induced resistance to the drugs tested. This included dependencies involving the transporters SLC11A2/SLC16A1 for artemisinin derivatives and SLC35A2/SLC38A5 for cisplatin. The functional dependence on SLCs observed for a significant proportion of the screened compounds suggests a widespread role for SLCs in the uptake and cellular activity of cytotoxic drugs and provides an experimentally validated set of SLC-drug associations for a number of clinically relevant compounds.


Assuntos
Resistência a Medicamentos/genética , Proteínas Carreadoras de Solutos/metabolismo , Sistemas de Transporte de Aminoácidos Neutros/genética , Sistemas de Transporte de Aminoácidos Neutros/metabolismo , Antineoplásicos , Fenômenos Bioquímicos , Transporte Biológico/genética , Transporte Biológico/fisiologia , Sistemas CRISPR-Cas , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Resistência a Medicamentos/fisiologia , Testes Genéticos , Humanos , Transportadores de Ácidos Monocarboxílicos/genética , Transportadores de Ácidos Monocarboxílicos/metabolismo , Proteínas de Transporte de Monossacarídeos/genética , Proteínas de Transporte de Monossacarídeos/metabolismo , Transporte Proteico/fisiologia , Proteínas Carreadoras de Solutos/fisiologia , Simportadores/genética , Simportadores/metabolismo
14.
Int J Mol Sci ; 21(4)2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-32070009

RESUMO

Following photosynthesis, sucrose is translocated to sink organs, where it provides the primary source of carbon and energy to sustain plant growth and development. Sugar transporters from the SWEET (sugar will eventually be exported transporter) family are rate-limiting factors that mediate sucrose transport across concentration gradients, sustain yields, and participate in reproductive development, plant senescence, stress responses, as well as support plant-pathogen interaction, the focus of this study. We identified 25 SWEET genes in the walnut genome and distinguished each by its individual gene structure and pattern of expression in different walnut tissues. Their chromosomal locations, cis-acting motifs within their 5' regulatory elements, and phylogenetic relationship patterns provided the first comprehensive analysis of the SWEET gene family of sugar transporters in walnut. This family is divided into four clades, the analysis of which suggests duplication and expansion of the SWEET gene family in Juglans regia. In addition, tissue-specific gene expression signatures suggest diverse possible functions for JrSWEET genes. Although these are commonly used by pathogens to harness sugar products from their plant hosts, little was known about their role during Xanthomonas arboricola pv. juglandis (Xaj) infection. We monitored the expression profiles of the JrSWEET genes in different tissues of "Chandler" walnuts when challenged with pathogen Xaj417 and concluded that SWEET-mediated sugar translocation from the host is not a trigger for walnut blight disease development. This may be directly related to the absence of type III secretion system-dependent transcription activator-like effectors (TALEs) in Xaj417, which suggests different strategies are employed by this pathogen to promote susceptibility to this major aboveground disease of walnuts.


Assuntos
Juglans/genética , Proteínas de Membrana Transportadoras/genética , Doenças das Plantas/genética , Proteínas de Plantas/genética , Transporte Biológico/genética , Regulação da Expressão Gênica de Plantas/genética , Genoma de Planta/genética , Juglans/microbiologia , Proteínas de Membrana Transportadoras/classificação , Família Multigênica/genética , Filogenia , Desenvolvimento Vegetal/genética , Doenças das Plantas/microbiologia , Sistemas de Secreção Tipo III/genética , Xanthomonas/genética , Xanthomonas/patogenicidade
15.
Fluids Barriers CNS ; 17(1): 17, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32046769

RESUMO

BACKGROUND: Cerebrospinal fluid (CSF) is mainly produced by the choroid plexus (CP) located in brain ventricles. Although derived from blood plasma, it is nearly protein-free (~ 250-fold less) and contains about 2-20-fold less free amino acids, with the exception of glutamine (Gln) which is nearly equal. The aim of this study was to determine which amino acid transporters are expressed in mouse CP epithelium in order to gain understanding about how this barrier maintains the observed amino acid concentration gradient. METHODS: Expression of amino acid transporters was assessed in isolated choroid plexuses (CPs) by qRT-PCR followed by localization studies using immunofluorescence with specific antibodies. The impact of LAT2 (Slc7a8) antiporter deletion on CSF amino acids was determined. RESULTS: The purity of isolated choroid plexuses was tested on the mRNA level using specific markers, in particular transthyretin (Ttr) that was enriched 330-fold in CP compared to cerebral tissue. In a first experimental round, 14 out of 32 Slc amino acid transporters tested on the mRNA level by qPCR were selected for further investigation. Out of these, five were considered highly expressed, SNAT1 (Slc38a1), SNAT3 (Slc38a3), LAT2 (Slc7a8), ASC1 (Slc7a10) and SIT1 (Slc6a20b). Three of them were visualized by immunofluorescence: SNAT1 (Slc38a1), a neutral amino acid-Na+ symporter, found at the blood side basolateral membrane of CP epithelium, while SNAT3 (Slc38a3), an amino acid-Na+ symporter and H+ antiporter, as well as LAT2 (Slc7a8), a neutral amino acid antiporter, were localized at the CSF-facing luminal membrane. In a LAT2 knock-out mouse model, CSF Gln was unchanged, whereas other amino acids normally 2-20-fold lower than in plasma, were increased, in particular the LAT2 uptake substrates leucine (Leu), valine (Val) and tryptophan (Trp) and some other amino acids such as glutamate (Glu), glycine (Gly) and proline (Pro). CONCLUSION: These results suggest that Gln is actively transported by SNAT1 from the blood into CP epithelial cells and then released luminally into CSF via SNAT3 and LAT2. Its efflux via LAT2 may drive the reuptake from the CSF of essential amino acid substrates of this antiporter and thereby participates to maintaining the amino acid gradient between plasma and CSF.


Assuntos
Sistema y+ de Transporte de Aminoácidos/metabolismo , Sistemas de Transporte de Aminoácidos Neutros/metabolismo , Aminoácidos/líquido cefalorraquidiano , Células Epiteliais/metabolismo , Cadeias Leves da Proteína-1 Reguladora de Fusão/metabolismo , Homeostase , Sistema y+ de Transporte de Aminoácidos/genética , Animais , Transporte Biológico/genética , Transporte Biológico/fisiologia , Células Cultivadas , Plexo Corióideo/metabolismo , Feminino , Cadeias Leves da Proteína-1 Reguladora de Fusão/genética , Ácido Glutâmico/metabolismo , Homeostase/fisiologia , Masculino , Camundongos Knockout , Pré-Albumina/metabolismo
16.
Int J Mol Sci ; 21(4)2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32075298

RESUMO

Improving nitrogen use efficiency (NUE) is very important for crops throughout the world. Rice mainly utilizes ammonium as an N source, but it also has four NRT2 genes involved in nitrate transport. The OsNRT2.3b transporter is important for maintaining cellular pH under mixed N supplies. Overexpression of this transporter driven by a ubiquitin promoter in rice greatly improved yield and NUE. This strategy for improving the NUE of crops may also be important for other cereals such as wheat and barley, which also face the challenges of nutrient uptake balance. To test this idea, we constructed transgenic barley lines overexpressing OsNRT2.3b. These transgenic barley lines overexpressing the rice transporter exhibited improved growth, yield, and NUE. We demonstrated that NRT2 family members and the partner protein HvNAR2.3 were also up-regulated by nitrate treatment (0.2 mM) in the transgenic lines. This suggests that the expression of OsNRT2.3b and other HvNRT2 family members were all up-regulated in the transgenic barley to increase the efficiency of N uptake and usage. We also compared the ubiquitin (Ubi) and a phloem-specific (RSs1) promoter-driven expression of OsNRT2.3b. The Ubi promoter failed to improve nutrient uptake balance, whereas the RSs1 promoter succeed in increasing the N, P, and Fe uptake balance. The nutrient uptake enhancement did not include Mn and Mg. Surprisingly, we found that the choice of promoter influenced the barley phenotype, not only increasing NUE and grain yield, but also improving nutrient uptake balance.


Assuntos
Proteínas de Transporte de Ânions/genética , Transporte Biológico/genética , Hordeum/genética , Oryza/genética , Regulação da Expressão Gênica de Plantas , Hordeum/crescimento & desenvolvimento , Hordeum/metabolismo , Óxidos de Nitrogênio/metabolismo , Nutrientes/genética , Nutrientes/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Regiões Promotoras Genéticas/genética
17.
Infect Immun ; 88(5)2020 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-32094256

RESUMO

Peptidoglycan, the sugar-amino acid polymer that composes the bacterial cell wall, requires a significant expenditure of energy to synthesize and is highly immunogenic. To minimize the loss of an energetically expensive metabolite and avoid host detection, bacteria often recycle their peptidoglycan, transporting its components back into the cytoplasm, where they can be used for subsequent rounds of new synthesis. The peptidoglycan-recycling substrate binding protein (SBP) MppA, which is responsible for recycling peptidoglycan fragments in Escherichia coli, has not been annotated for most intracellular pathogens. One such pathogen, Chlamydia trachomatis, has a limited capacity to synthesize amino acids de novo and therefore must obtain oligopeptides from its host cell for growth. Bioinformatics analysis suggests that the putative C. trachomatis oligopeptide transporter OppABCDF (OppABCDF Ct ) encodes multiple SBPs (OppA1 Ct , OppA2 Ct , and OppA3 Ct ). Intracellular pathogens often encode multiple SBPs, while only one, OppA, is encoded in the E. coli opp operon. We hypothesized that the putative OppABCDF transporter of C. trachomatis functions in both oligopeptide transport and peptidoglycan recycling. We coexpressed the putative SBP genes (oppA1Ct , oppA2Ct , oppA3Ct ) along with oppBCDFCt in an E. coli mutant lacking the Opp transporter and determined that all three chlamydial OppA subunits supported oligopeptide transport. We also demonstrated the in vivo functionality of the chlamydial Opp transporter in C. trachomatis Importantly, we found that one chlamydial SBP, OppA3 Ct , possessed dual substrate recognition properties and is capable of transporting peptidoglycan fragments (tri-diaminopimelic acid) in E. coli and in C. trachomatis These findings suggest that Chlamydia evolved an oligopeptide transporter to facilitate the acquisition of oligopeptides for growth while simultaneously reducing the accumulation of immunostimulatory peptidoglycan fragments in the host cell cytosol. The latter property reflects bacterial pathoadaptation that dampens the host innate immune response to Chlamydia infection.


Assuntos
Chlamydia trachomatis/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Oligopeptídeos/metabolismo , Peptidoglicano/metabolismo , Aminoácidos/genética , Aminoácidos/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Transporte Biológico/genética , Transporte Biológico/fisiologia , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Linhagem Celular Tumoral , Parede Celular/genética , Parede Celular/metabolismo , Infecções por Chlamydia/metabolismo , Chlamydia trachomatis/genética , Citosol/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Genes Bacterianos/genética , Células HeLa , Humanos , Imunidade Inata/genética , Proteínas de Membrana Transportadoras/genética , Oligopeptídeos/genética , Óperon/genética , Peptidoglicano/genética
18.
Biosens Bioelectron ; 154: 112056, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32093894

RESUMO

Extracellular vesicles (EVs) are secreted by a variety of cells. They are known for their pertinent role in intercellular communication, and participation in different pathological processes, making them ideal candidate for utilization as a biomarker for diagnosis and treatment of diseases. In contemporary years, the concept of a well-established liquid biopsy technology, and detection and utilization of EVs as a biomarkers have received unprecedented attention. Many rapid and precise EVs detection methods have been proposed, however, majority of them detect EVs in a bulk. As the prevalent heterogeneity of single extracellular vesicle (SEV) plays an important role in the analysis of disease progression, therefore, to prevent information loss, increased attention has been paid to SEV detection with remarkable successes. Technologies like fluorescence labeling, micro imaging and microfluidic chip were successfully employed for EVs detection at SEV level. This review summarizes the recent advances in SEV detection methods, their potential targets, applications as well as concludes future prospects for developing new SEV detection strategies.


Assuntos
Biomarcadores/química , Técnicas Biossensoriais , Vesículas Extracelulares/química , Transporte Biológico/genética , Comunicação Celular/genética , Humanos , Biópsia Líquida/métodos , Microfluídica/métodos
19.
J Biol Chem ; 295(7): 1829-1842, 2020 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-31896576

RESUMO

The multispecific organic anion transporters, OAT1 (SLC22A6) and OAT3 (SLC22A8), the main kidney elimination pathways for many common drugs, are often considered to have largely-redundant roles. However, whereas examination of metabolomics data from Oat-knockout mice (Oat1 and Oat3KO) revealed considerable overlap, over a hundred metabolites were increased in the plasma of one or the other of these knockout mice. Many of these relatively unique metabolites are components of distinct biochemical and signaling pathways, including those involving amino acids, lipids, bile acids, and uremic toxins. Cheminformatics, together with a "logical" statistical and machine learning-based approach, identified a number of molecular features distinguishing these unique endogenous substrates. Compared with OAT1, OAT3 tends to interact with more complex substrates possessing more rings and chiral centers. An independent "brute force" approach, analyzing all possible combinations of molecular features, supported the logical approach. Together, the results suggest the potential molecular basis by which OAT1 and OAT3 modulate distinct metabolic and signaling pathways in vivo As suggested by the Remote Sensing and Signaling Theory, the analysis provides a potential mechanism by which "multispecific" kidney proximal tubule transporters exert distinct physiological effects. Furthermore, a strong metabolite-based machine-learning classifier was able to successfully predict unique OAT1 versus OAT3 drugs; this suggests the feasibility of drug design based on knockout metabolomics of drug transporters. The approach can be applied to other SLC and ATP-binding cassette drug transporters to define their nonredundant physiological roles and for analyzing the potential impact of drug-metabolite interactions.


Assuntos
Metabolômica , Proteína 1 Transportadora de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos Sódio-Independentes/metabolismo , Toxinas Biológicas/metabolismo , Trifosfato de Adenosina/genética , Animais , Ácidos e Sais Biliares/metabolismo , Transporte Biológico/genética , Humanos , Inativação Metabólica/genética , Túbulos Renais Proximais/metabolismo , Aprendizado de Máquina , Camundongos , Camundongos Knockout , Proteína 1 Transportadora de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos Sódio-Independentes/genética , Transdução de Sinais
20.
Biochim Biophys Acta Mol Cell Res ; 1867(7): 118641, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-31893523

RESUMO

Cilia are ubiquitous in mammalian cells. The formation and assembly of cilia depend on the normal functioning of the ciliary transport system. In recent years, various proteins involved in the intracellular transport of the cilium have attracted attention, as many diseases are caused by disorders in cilia formation. Intraflagellar transport 20 (IFT20) is a subunit of IFT complex B, which contains approximately 20 protein particles. Studies have shown that defects in IFT20 are associated with numerous system -related diseases, such as those of the urinary system, cardiovascular system, skeletal system, nervous system, immune system, reproductive system, and respiratory system. This review summarizes current research on IFT20.We describe studies related to the role of IFT20 in cilia formation and discuss new targets for treating diseases associated with ciliary dysplasia.


Assuntos
Transporte Biológico/genética , Proteínas de Transporte/genética , Cílios/genética , Ciliopatias/genética , Proteínas de Transporte/antagonistas & inibidores , Cílios/metabolismo , Ciliopatias/tratamento farmacológico , Ciliopatias/patologia , Humanos
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