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1.
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
2.
Expert Opin Drug Metab Toxicol ; 16(2): 149-164, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31951754

RESUMO

Introduction: Membrane transporters of the SLC and ABC families are abundantly expressed in the liver, where they control the transfer of drugs/drug metabolites across the sinusoidal and canalicular hepatocyte membranes and play a pivotal role in hepatic drug clearance. Noninvasive imaging methods, such as PET, SPECT or MRI, allow for measuring the activity of hepatic transporters in vivo, provided that suitable transporter imaging probes are available.Areas covered: We give an overview of the working principles of imaging-based assessment of hepatic transporter activity. We discuss different currently available PET/SPECT radiotracers and MRI contrast agents and their applications to measure hepatic transporter activity in health and disease. We cover mathematical modeling approaches to obtain quantitative parameters of transporter activity and provide a critical assessment of methodological limitations and challenges associated with this approach.Expert opinion: PET in combination with pharmacokinetic modeling can be potentially applied in drug development to study the distribution of new drug candidates to the liver and their clearance mechanisms. This approach bears potential to mechanistically assess transporter-mediated drug-drug interactions, to assess the influence of disease on hepatic drug disposition and to validate and refine currently available in vitro-in vivo extrapolation methods to predict hepatic clearance of drugs.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Fígado/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Animais , Transporte Biológico , Hepatócitos/metabolismo , Humanos , Imagem por Ressonância Magnética , Modelos Teóricos , Preparações Farmacêuticas/metabolismo , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada de Emissão de Fóton Único
3.
Chemosphere ; 241: 124968, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31606578

RESUMO

The solute carriers (SLCs) are membrane proteins that transport many endogenous and exogenous substances such as xenobiotic toxins. Bivalve mollusks, mainly feeding on microalgae, show marked capacity to accumulate paralytic shellfish toxins (PSTs), the most common and hazardous marine biotoxins produced by dinoflagellates. Exploring the SLCs related to PST accumulation in bivalve could benefit our understanding about the mechanisms of PST bioavailability in bivalve and the adaptations of these species. Herein, we provided the first systematic analysis of SLC genes in mollusks, which identified 673 SLCs (PySLCs, 48 subfamilies) in Yesso scallop (Patinopecten yessoensis), 510 (48 subfamilies) in Pacific oyster (Crassostrea gigas), and 350 (47 subfamilies) in gastropod owl limpet (Lottia gigantea). Significant expansion of subfamilies SLC5, SLC6, SLC16, and SLC23 in scallop, and SLC46 subfamily in both scallop and oyster were revealed. Different PySLC members were highly expressed in the developmental stages and adult tissues, and hepatopancreas harboured more specifically expressed PySLCs than other tissues/organs. After feeding the scallops with PST-producing dinoflagellate, 131 PySLCs were regulated and more than half of them were from the expanded subfamilies. The trend of expression fold change in regulated PySLCs was consistent with that of PST changes in hepatopancreas, implying the possible involvement of these PySLCs in PST transport and homeostasis. In addition, the PySLCs from the expanded subfamily were revealed to be under positive selection, which might be related to lineage-specific adaptation to the marine environments with algae derived biotoxins.


Assuntos
Dinoflagelados/patogenicidade , Regulação da Expressão Gênica/efeitos dos fármacos , Pectinidae/genética , Proteínas Carreadoras de Solutos/genética , Animais , Transporte Biológico , Dinoflagelados/metabolismo , Homeostase , Intoxicação por Frutos do Mar , Toxinas Biológicas/toxicidade
4.
Hum Genet ; 138(11-12): 1359-1377, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31679053

RESUMO

The human solute carrier (SLC) superfamily of transporters is comprised of over 400 membrane-bound proteins, and plays essential roles in a multitude of physiological and pharmacological processes. In addition, perturbation of SLC transporter function underlies numerous human diseases, which renders SLC transporters attractive drug targets. Common genetic polymorphisms in SLC genes have been associated with inter-individual differences in drug efficacy and toxicity. However, despite their tremendous clinical relevance, epidemiological data of these variants are mostly derived from heterogeneous cohorts of small sample size and the genetic SLC landscape beyond these common variants has not been comprehensively assessed. In this study, we analyzed Next-Generation Sequencing data from 141,456 individuals from seven major human populations to evaluate genetic variability, its functional consequences, and ethnogeographic patterns across the entire SLC superfamily of transporters. Importantly, of the 204,287 exonic single-nucleotide variants (SNVs) which we identified, 99.8% were present in less than 1% of analyzed alleles. Comprehensive computational analyses using 13 partially orthogonal algorithms that predict the functional impact of genetic variations based on sequence information, evolutionary conservation, structural considerations, and functional genomics data revealed that each individual genome harbors 29.7 variants with putative functional effects, of which rare variants account for 18%. Inter-ethnic variability was found to be extensive, and 83% of deleterious SLC variants were only identified in a single population. Interestingly, population-specific carrier frequencies of loss-of-function variants in SLC genes associated with recessive Mendelian disease recapitulated the ethnogeographic variation of the corresponding disorders, including cystinuria in Jewish individuals, type II citrullinemia in East Asians, and lysinuric protein intolerance in Finns, thus providing a powerful resource for clinical geneticists to inform about population-specific prevalence and allelic composition of Mendelian SLC diseases. In summary, we present the most comprehensive data set of SLC variability published to date, which can provide insights into inter-individual differences in SLC transporter function and guide the optimization of population-specific genotyping strategies in the bourgeoning fields of personalized medicine and precision public health.


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Proteínas de Membrana Transportadoras/genética , Família Multigênica , Polimorfismo Genético , Proteínas Carreadoras de Solutos/genética , Humanos
5.
Int J Mol Sci ; 20(21)2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31661895

RESUMO

Kinetic models have been employed to understand the logic of substrate transport through transporters of the Solute Carrier (SLC) family. All SLC transporters operate according to the alternate access model, which posits that substrate transport occurs in a closed loop of partial reactions (i.e., a transport cycle). Kinetic models can help to find realistic estimates for conformational transitions between individual states of the transport cycle. When constrained by experimental results, kinetic models can faithfully describe the function of a candidate transporter at a pre-steady state. In addition, we show that kinetic models can accurately predict the intra- and extracellular substrate concentrations maintained by the transporter at a steady state, even under the premise of loose coupling between the electrochemical gradient of the driving ion and of the substrate. We define the criteria for the design of a credible kinetic model of the SLC transporter. Parsimony is the guiding principle of kinetic modeling. We argue, however, that the level of acceptable parsimony is limited by the need to account for the substrate gradient established by a secondary active transporter, and for random order binding of co-substrates and substrate. Random order binding has consistently been observed in transporters of the SLC group.


Assuntos
Serotonina/metabolismo , Sódio/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Transporte Biológico , Íons/química , Cinética , Modelos Biológicos , Sódio/química , Termodinâmica
6.
Adv Exp Med Biol ; 1141: 1-12, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571163

RESUMO

Absorption, distribution, and excretion of drugs are involved in drug transport across plasma membrane, most of which are mediated by drug transporters. These drug transporters are generally divided into solute carrier (SLC) family and ATP-binding cassette (ABC) family. These transporters not only mediate transport of therapeutic drugs across membrane but also transport various kinds of endogenous compounds. Thus besides being participated in disposal of drug and its clinical efficacy/toxicity, these transporters also play vital roles in maintaining cell homeostasis via regulating transport of endogenous compounds. This chapter will outline classification of drug transporters, their roles in drug disposal/drug response, and remote communication between tissues/organs.


Assuntos
Transportadores de Cassetes de Ligação de ATP , Proteínas Carreadoras de Solutos , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Transporte Biológico , Comunicação Celular , Membrana Celular/metabolismo , Humanos , Preparações Farmacêuticas/metabolismo , Proteínas Carreadoras de Solutos/metabolismo
7.
Adv Exp Med Biol ; 1141: 101-202, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31571165

RESUMO

Solute carrier (SLC) family transporters utilize an electrochemical potential difference or an ion gradient generated by primary active transporters for transporting their substrates across biological membranes. These transporters are categorized as facilitated transporters or secondary active transporters. More than 300 SLC transporters have been identified. SLC transporters related to drug transport mainly include SLC21 gene subfamily (organic anion-transporting polypeptides, OATPs), SLC22A gene subfamily (organic anion transporters, OATs; organic cation transporters, OCTs; or organic cation/carnitine transporters, OCTNs), SLC15A gene subfamily (peptide transporters, PEPTs), and SLC47A gene subfamily (multidrug and toxin extrusion, MATEs). In general, OCTs transport organic cations, OATPs transport large and fairly hydrophobic organic anions, OATs transport the smaller and more hydrophilic organic anions, and PEPTs are responsible for the uptake of di-/tripeptides and peptide-like drugs. MATEs are responsible for efflux of organic cations. These transporters also transport some endogenous substances, indicating that the dysfunction of SLCs not only disrupts homeostasis but also largely impacts on the disposition of their substrate drugs. This chapter will discuss these SLC family transporters, with an emphasis on tissue distribution, substrate specificity, transporter physiology, and clinical significance.


Assuntos
Proteínas Carreadoras de Solutos , Animais , Cátions/metabolismo , Humanos , Peptídeos/metabolismo , Preparações Farmacêuticas/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Especificidade por Substrato , Distribuição Tecidual/fisiologia
8.
Am J Physiol Gastrointest Liver Physiol ; 317(6): G751-G762, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31509437

RESUMO

Organic anion transporting polypeptide (OATP) 1B3-1B7 (LST-3TM12) is a member of the OATP1B [solute carrier organic anion transporter (SLCO) 1B] family. This transporter is not only functional but also expressed in the membrane of the smooth endoplasmic reticulum of hepatocytes and enterocytes. OATP1B3-1B7 is a splice variant of SLCO1B3 in which the initial part is encoded by SLCO1B3, whereas the rest of the mRNA originates from the gene locus of SLCO1B7. In this study, we not only showed that SLCO1B3 and the mRNA encoding for OATP1B3-1B7 share the 5' untranslated region but also that silencing of an initial SLCO1B3 exon lowered the amount of SLCO1B3 and of SLCO1B7 mRNA in Huh-7 cells. To validate the assumption that both transcripts are regulated by the same promoter we tested the influence of the bile acid sensor farnesoid X receptor (FXR) on their transcription. Treatment of Huh-7 and HepaRG cells with activators of this known regulator of OATP1B3 not only increased SLCO1B3 but also OATP1B3-1B7 mRNA transcription. Applying a heterologous expression system, we showed that several bile acids interact with OATP1B3-1B7 and that taurocholic acid and lithocholic acid are OATP1B3-1B7 substrates. As OATP1B3-1B7 is located in the smooth endoplasmic reticulum, it may grant access to metabolizing enzymes. In accordance are our findings showing that the OATP1B3-1B7 inhibitor bromsulphthalein significantly reduced uptake of bile acids into human liver microsomes. Taken together, we report that OATP1B3-1B7 transcription can be modulated with FXR agonists and antagonists and that OATP1B3-1B7 transports bile acids.NEW & NOTEWORTHY Our study on the transcriptional regulation of the novel organic anion transporting polypeptide (OATP) 1B3-1B7 concludes that the promoter of solute carrier organic anion transporter (SLCO) 1B3 governs SLCO1B3-1B7 transcription. Moreover, the transcription of OATP1B3-1B7 can be modulated by farnesoid X receptor (FXR) agonists and antagonists. FXR is a major regulator in bile acid homeostasis that links OATP1B3-1B7 to this physiological function. Findings in transport studies with OATP1B3-1B7 suggest that this transporter interacts with the herein tested bile acids.


Assuntos
Ácidos e Sais Biliares/fisiologia , Isoxazóis/farmacologia , Transportadores de Ânions Orgânicos , Receptores Citoplasmáticos e Nucleares , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto , Proteínas Carreadoras de Solutos , Antineoplásicos/farmacologia , Transporte Biológico/fisiologia , Regulação da Expressão Gênica , Redes Reguladoras de Genes/fisiologia , Células HeLa , Células Hep G2 , Humanos , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores Citoplasmáticos e Nucleares/antagonistas & inibidores , Receptores Citoplasmáticos e Nucleares/genética , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/genética , Membro 1B3 da Família de Transportadores de Ânion Orgânico Carreador de Soluto/metabolismo , Proteínas Carreadoras de Solutos/genética , Proteínas Carreadoras de Solutos/metabolismo , Fatores de Transcrição , Ativação Transcricional
9.
Curr Drug Metab ; 20(9): 742-755, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31475894

RESUMO

BACKGROUND: Long-term intake of a high-fat diet is a crucial factor contributing to obesity, which has become a global public health problem. Progressive obesity subsequently leads to hepatic injury, renal damage and intestinal atrophy. Transporters expressed in the liver, kidney and intestine play important roles in the deposition of nutrients and drugs, but researchers have not clearly determined whether/how the expression of transporters changes after long-term administration of a High-Fat Diet (HFD). This study aims to explore the effects of the long-term administration of a HFD on the expression of drug transporters in the liver, kidney and intestine in mice and to provide useful information for medical applications in the clinic. METHODS: Male C57BL/6J mice were fed either a basal diet or HFD for 24 weeks, and oral glucose tolerance tests were performed after 3, 11 and 23 weeks. Serum was obtained to measure lipid metabolism, inflammatory mediators, renal function and hepatic function. Adipose tissues, kidney, pancreas and liver were collected for hematoxylin and eosin (H&E) staining after 4, 12 and 24 weeks. The mRNA and proteins expression of drug transporters in the liver, kidney and intestine were detected using real-time PCR and western blot, respectively. RESULTS: Compared with the control group, long-term HFD administration significantly increased the adipose index. The serum lipid levels, including Total Cholesterol (TC), Triglyceride (TG), and Low-Density Lipoprotein Cholesterol (LDL-C), as well as the levels of the inflammatory cytokines Interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) were significantly elevated in HFD-induced obese mice. H&E staining revealed pathological changes in the adipose cells, liver, kidney and pancreas from the obese group following the long-term administration of the HFD. The liver of the obese group presented increased mRNA expression of the efflux transporter Mrp2 and uptake transporter Oat2 at 24 weeks. The relative expression of Oat2 increased 4.08-fold and the protein expression of Oat2 was upregulated at 24 weeks in HFD-fed mice, while the mRNA expression of the uptake transporters Oct1, Oatp1b2 and Oatp1a4 decreased by 79%, 61% and 19%, respectively. The protein expression of Oct1 was significantly downregulated in obese mice at 12 weeks. The mRNA expression of the efflux transporter Mdr1a was significantly reduced in HFD-fed mice compared with the control group at 24 weeks. Western blot showed that the trend of protein level of Mdr1 was consistent with the mRNA expression. In the kidney, the level of the Oct2 mRNA increased 1.92- and 2.46-fold at 4 and 12 weeks in HFD-fed mice, respectively. The expression of the Oat1 and Oat3 mRNAs was markedly downregulated in the kidneys of mice with HFD-induced obesity at 4 weeks. The decrease of 72% and 21% in Mdr1a mRNA expression was observed in the obese model at 4 weeks and 12 weeks, respectively. Western blot showed that the protein levels of Mdr1 and Oat1 were consistent with the mRNA expression. The qPCR experiments showed a 2.87-fold increase in Bcrp mRNA expression at 24 weeks, and the expression of the Pept1 mRNA increased 2.84-fold in intestines of obese mice subjected to long-term administration of the HFD compared with control mice at 12 weeks. Western blot showed that the trend of protein levels of Mdr1 and Mrp2 were consistent with the mRNA expression. CONCLUSION: The expression of uptake and efflux transporters mRNAs and protein levels were altered in obese mice compared with control mice, providing scientific evidence for future medical applications in the clinic.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Rim/metabolismo , Fígado/metabolismo , Obesidade/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Tecido Adiposo , Animais , Intestinos/patologia , Rim/patologia , Fígado/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Modelos Animais , Obesidade/patologia , Pâncreas/patologia
10.
Nature ; 572(7771): 614-619, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31435015

RESUMO

Branched-chain amino acid (BCAA; valine, leucine and isoleucine) supplementation is often beneficial to energy expenditure; however, increased circulating levels of BCAA are linked to obesity and diabetes. The mechanisms of this paradox remain unclear. Here we report that, on cold exposure, brown adipose tissue (BAT) actively utilizes BCAA in the mitochondria for thermogenesis and promotes systemic BCAA clearance in mice and humans. In turn, a BAT-specific defect in BCAA catabolism attenuates systemic BCAA clearance, BAT fuel oxidation and thermogenesis, leading to diet-induced obesity and glucose intolerance. Mechanistically, active BCAA catabolism in BAT is mediated by SLC25A44, which transports BCAAs into mitochondria. Our results suggest that BAT serves as a key metabolic filter that controls BCAA clearance via SLC25A44, thereby contributing to the improvement of metabolic health.


Assuntos
Tecido Adiposo Marrom/metabolismo , Sistemas de Transporte de Aminoácidos/metabolismo , Aminoácidos de Cadeia Ramificada/metabolismo , Metabolismo Energético , Homeostase , Proteínas Mitocondriais/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Termogênese , Tecido Adiposo Marrom/citologia , Animais , Temperatura Baixa , Intolerância à Glucose/metabolismo , Humanos , Masculino , Camundongos , Mitocôndrias/metabolismo , Obesidade/metabolismo
11.
Artigo em Inglês | MEDLINE | ID: mdl-31422161

RESUMO

The circadian clock system drives many physiological processes, including plasma concentration of glucocorticoids and epithelial transport of some ions and nutrients. As glucocorticoids entrain the circadian rhythms in various peripheral organs, we examined whether adrenalectomy affects the expression and circadian rhythmicity of intestinal transporters of the solute carrier (SLC) and ATP-binding cassette (ABC) families, which participate in intestinal barriers for absorption of nutrients, nonnutrients and oral drugs. The rat jejunum showed rhythmic circadian profiles of Sglt1, Pept1, Nhe3, Mdr1 and Mrp2 but not Mct1, Oct1, Octn1, Oatp1, Cnt1 and Bcrp. With the exception of Pept1 and Mct1, adrenalectomy decreased the expression of all rhythmic and arrhythmic transporters including the amplitude of Sglt1 and Nhe3 rhythms but minimally affected the phases of rhythmic transporters except of Nhe3. Similarly, adrenalectomy downregulated the expression of rhythmic (Pparα, Hlf, Pgc1α) and arrhythmic (Hnf1ß, Hnf4α) transcription factors, which are known to regulate the expression of transporters. We conclude that endogenous corticosteroids have a profound effect on the expression of intestinal SLC and ABC transporters and their nuclear transcription factors. The circulating corticosteroids are necessary for maintaining upregulated expression of Sglt1, Oct1, Octn1, Oatp1, Cnt1, Nhe3, Mdr1, Bcrp, Mrp2, Pparα, Pgc1α, Hnf1ß, Hnf4α and Hlf and for maintaining the high amplitude of Sglt1, Nhe3, Pparα, Pgc1α and Hlf circadian rhythms. The study demonstrates that signals from the adrenal gland are necessary for maintaining the expression of arrhythmic and rhythmic intestinal transporters and that changes in the secretion of corticosteroids associated with stress might reorganize intestinal transport barriers.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Adrenalectomia/efeitos adversos , Jejuno/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Animais , Ritmo Circadiano , Masculino , Ratos , Ratos Wistar
12.
J Appl Genet ; 60(3-4): 305-317, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31286439

RESUMO

The solute carrier (SLC) group of membrane transport proteins is crucial for cells via their control of import and export of vital molecules across the cellular membrane. Defects in these transporters with narrow substrate specificities cause monogenic disorders, giving us essential clues of their precise roles in cellular functioning. The SLC5 family in particular has been linked to various human diseases, of mild and severe phenotype as well as high and low prevalence. In this review, we describe the effects on health of SLC5 dysfunction and dysregulation by summarizing findings in patients with transporter gene defects. Patients display a plethora of pathologies which include glucose/galactose malabsorption, familiar renal glycosuria, thyroid dyshormonogenesis, and distal hereditary motor neuronopathies. In addition, the therapeutic potential of intervening in transporter activities for treating common diseases such as diabetes and cancer is explored.


Assuntos
Diabetes Mellitus/genética , Transtornos do Metabolismo de Glucose/genética , Neoplasias/genética , Proteínas Carreadoras de Solutos/genética , Diabetes Mellitus/metabolismo , Transtornos do Metabolismo de Glucose/metabolismo , Humanos , Neoplasias/metabolismo , Proteínas de Transporte de Sódio-Glucose
13.
Protein Sci ; 28(9): 1703-1712, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31306516

RESUMO

APEX2, an engineered ascorbate peroxidase for high activity, is a powerful tool for proximity labeling applications. Owing to its lack of disulfides and the calcium-independent activity, APEX2 can be applied intracellularly for targeted electron microscopy imaging or interactome mapping when fusing to a protein of interest. However, APEX2 fusion is often deleterious to the protein expression, which seriously hampers its wide utility. This problem is especially compelling when APEX2 is fused to structurally delicate proteins, such as multi-pass membrane proteins. In this study, we found that a cysteine-free single mutant C32S of APEX2 dramatically improved the expression of fusion proteins in mammalian cells without compromising the enzyme activity. We fused APEX2 and APEX2C32S to four multi-transmembrane solute carriers (SLCs), SLC1A5, SLC6A5, SLC6A14, and SLC7A1, and compared their expressions in stable HEK293T cell lines. Except the SLC6A5 fusions expressing at decent levels for both APEX2 (70%) and APEX2C32S (73%), other three SLC proteins showed significantly better expression when fusing to APEX2C32S (69 ± 13%) than APEX2 (29 ± 15%). Immunofluorescence and western blot experiments showed correct plasma membrane localization and strong proximity labeling efficiency in all four SLC-APEX2C32S cells. Enzyme kinetic experiments revealed that APEX2 and APEX2C32S have comparable activities in terms of oxidizing guaiacol. Overall, we believe APEX2C32S is a superior fusion tag to APEX2 for proximity labeling applications, especially when mismatched disulfide bonding or poor expression is a concern.


Assuntos
DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , Endonucleases/genética , Enzimas Multifuncionais/genética , Mutação , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Carreadoras de Solutos/genética , Membrana Celular/metabolismo , Cisteína/genética , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Endonucleases/metabolismo , Expressão Gênica , Células HEK293 , Humanos , Enzimas Multifuncionais/metabolismo , Engenharia de Proteínas , Proteínas Carreadoras de Solutos/metabolismo
14.
Pharmacol Rep ; 71(4): 738-745, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31207436

RESUMO

BACKGROUND: Analysis of results and conclusions in studies dedicated to pathology of the liver are usually based on comparison of pathological liver specimens and control/reference (considered as healthy) tissues. There are two main sources of the control liver samples used as the reference livers, i.e. deceased organ donor livers and non-tumorous tissue from metastatic livers, which are also applied for drug transporter investigations. However, no information has yet been published on drug transporters in these two major types of reference livers. METHODS: We explored ABC (P-gp, MRP1, MRP2, MRP3, MRP4, BCRP, BSEP) and SLC (NTCP, MCT1, OCT1, OCT3, OAT2, OATP1B1, OATP1B3, OATP2B1) family transporters expression (qPCR) and protein abundance (LC-MS/MS) in healthy donors (n = 9) and metastatic (n = 13) livers. RESULTS: The analysis of mRNA content revealed significant differences in ABCB11, ABCC1, ABCG2, SLC10A1, SLC16A1, SLCO1B1 and SLCO2B1 gene expression between livers from organ donors and patients who underwent surgical resection of metastatic tumors. The protein abundance of NTCP was significantly higher, whereas of P-gp significantly lower in non-tumorous tissues from metastatic livers. Greater inter-individual variability in protein abundance of all studied transporters in subjects with metastatic colon cancer was also observed. CONCLUSIONS: The results suggest that final conclusions in liver pathology studies may depend on the reference liver tissue used, especially in gene expression studies.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Neoplasias Hepáticas/metabolismo , Fígado/metabolismo , Preparações Farmacêuticas/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Feminino , Humanos , Fígado/patologia , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/secundário , Masculino , Pessoa de Meia-Idade , Proteômica , Proteínas Carreadoras de Solutos/genética , Doadores de Tecidos
15.
Mol Pharmacol ; 96(2): 128-137, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31127008

RESUMO

Drug transporters play a crucial role in pharmacokinetics. One subfamily of transporters with proven clinical relevance are the OATP1B transporters. Recently we identified a new member of the OATP1B family named OATP1B3-1B7 (LST-3TM12). This functional transporter is encoded by SLCO1B3 and SLCO1B7 OATP1B3-1B7 is expressed in hepatocytes and is located in the membrane of the smooth endoplasmic reticulum (SER). One aim of this study was to test whether OATP1B3-1B7 interacts with commercial drugs. First, we screened a selection of OATP1B substrates for inhibition of OATP1B3-1B7-mediated transport of dehydroepiandrosterone sulfate and identified several inhibitors. One such inhibitor was ezetimibe, which not only inhibited OATP1B3-1B7 but is also a substrate, as its cellular content was significantly increased in cells heterologously expressing the transporter. In humans, ezetimibe is extensively metabolized by hepatic and intestinal uridine-5'-diphospho-glucuronosyltransferases (UGTs), the catalytic site of which is located within the SER lumen. After verification of OATP1B3-1B7 expression in the small intestine, we determined in microsomes whether SER access can be modulated by inhibitors of OATP1B3-1B7. We were able to show that these compounds significantly reduced accumulation in small intestinal and hepatic microsomes, which influenced the rate of ezetimibe ß-D-glucuronide formation as determined in microsomes treated with bromsulphthalein. Notably, this molecule not only inhibits the herein reported transporter but also other transport systems. In conclusion, we report that multiple drugs interact with OATP1B3-1B7; for ezetimibe, we were able to show that SER access and metabolism is significantly reduced by bromsulphthalein, which is an inhibitor of OATP1B3-1B7. SIGNIFICANCE STATEMENT: OATP1B3-1B3 (LST-3TM12) is a transporter that has yet to be fully characterized. We provide valuable insight into the interaction potential of this transporter with several marketed drugs. Ezetimibe, which interacted with OATP1B3-1B7, is highly metabolized by uridine-5'-diphospho-glucuronosyltransferases (UGTs), whose catalytic site is located within the smooth endoplasmic reticulum (SER) lumen. Through microsomal assays with ezetimibe and the transport inhibitor bromsulphthalein we investigated the interdependence of SER access and the glucuronidation rate of ezetimibe. These findings led us to the hypothesis that access or exit of drugs to the SER is orchestrated by SER transporters such as OATP1B3-1B7.


Assuntos
Retículo Endoplasmático Liso/química , Ezetimiba/farmacocinética , Transportadores de Ânions Orgânicos/metabolismo , Proteínas Carreadoras de Solutos/metabolismo , Sulfobromoftaleína/farmacologia , Transporte Biológico , Domínio Catalítico , Glucuronosiltransferase/química , Células HeLa , Humanos , Intestino Delgado/metabolismo , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo
16.
J Pharmacol Exp Ther ; 370(1): 72-83, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30975793

RESUMO

Hepatic uptake transporters [solute carriers (SLCs)], including organic anion transporting polypeptide (OATP) 1B1, OATP1B3, OATP2B1, sodium-dependent taurocholate cotransporting polypeptide (NTCP), and organic anion (OAT2) and organic cation (OCT1) transporters, play a key role in determining the systemic and liver exposure of chemically diverse drugs. Here, we established a phenotyping approach to quantify the contribution of the six SLCs, and passive diffusion, to the overall uptake using plated human hepatocytes (PHHs). First, selective inhibitor conditions were identified by screening about 20 inhibitors across the six SLCs using single-transfected human embryonic kidney 293 cells. Data implied rifamycin SV (20 µM) inhibits three OATPs, while rifampicin (5 µM) inhibits OATP1B1/1B3 only. Further, hepatitis B virus myristoylated-preS1 peptide (0.1 µM), quinidine (100 µM), and ketoprofen (100-300 µM) are relatively selective against NTCP, OCT1, and OAT2, respectively. Second, using these inhibitory conditions, the fraction transported (ft ) by the individual SLCs was characterized for 20 substrates with PHH. Generally, extended clearance classification system class 1A/3A (e.g., warfarin) and 1B/3B compounds (e.g., statins) showed predominant OAT2 and OATP1B1/1B3 contribution, respectively. OCT1-mediated uptake was prominent for class 2/4 compounds (e.g., metformin). Third, in vitro ft values were corrected using quantitative proteomics data to obtain "scaled ft " Fourth, in vitro-in vivo extrapolation of the scaled OATP1B1/1B3 ft was assessed, leveraging statin clinical drug-drug interaction data with rifampicin as the perpetrator. Finally, we outlined a novel stepwise strategy to implement phenotypic characterization of SLC-mediated hepatic uptake for new molecular entities and drugs in a drug discovery and development setting.


Assuntos
Hepatócitos/metabolismo , Fígado/citologia , Fígado/metabolismo , Preparações Farmacêuticas/metabolismo , Fenótipo , Proteínas Carreadoras de Solutos/metabolismo , Transporte Biológico/efeitos dos fármacos , Interações Medicamentosas , Células HEK293 , Hepatócitos/efeitos dos fármacos , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/metabolismo , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Fígado/efeitos dos fármacos , Rifampina/metabolismo , Rifampina/farmacologia
17.
Nutrients ; 11(4)2019 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-31010163

RESUMO

It is difficult to know if the cause for obesity is the type of sweetener, high fat (HF) content, or the combination of sweetener and fat. The purpose of the present work was to study different types of sweeteners; in particular, steviol glycosides (SG), glucose, fructose, sucrose, brown sugar, honey, SG + sucrose (SV), and sucralose on the functionality of the adipocyte. Male Wistar rats were fed for four months with different sweeteners or sweetener with HF added. Taste receptors T1R2 and T1R3 were differentially expressed in the tongue and intestine by sweeteners and HF. The combination of fat and sweetener showed an additive effect on circulating levels of GIP and GLP-1 except for honey, SG, and brown sugar. In adipose tissue, sucrose and sucralose stimulated TLR4, and c-Jun N-terminal (JNK). The combination of HF with sweeteners increased NFκB, with the exception of SG and honey. Honey kept the insulin signaling pathway active and the smallest adipocytes in white (WAT) and brown (BAT) adipose tissue and the highest expression of adiponectin, PPARγ, and UCP-1 in BAT. The addition of HF reduced mitochondrial branched-chain amino transferase (BCAT2) branched-chain keto acid dehydrogenase E1 (BCKDH) and increased branched chain amino acids (BCAA) levels by sucrose and sucralose. Our data suggests that the consumption of particular honey maintained functional adipocytes despite the consumption of a HF diet.


Assuntos
Tecido Adiposo/efeitos dos fármacos , Dieta Hiperlipídica , Açúcares da Dieta/farmacologia , Insulina/sangue , Edulcorantes/farmacologia , Papilas Gustativas/metabolismo , Receptor 4 Toll-Like/metabolismo , 3-Metil-2-Oxobutanoato Desidrogenase (Lipoamida)/sangue , Adiponectina/sangue , Tecido Adiposo/citologia , Animais , Gorduras na Dieta/administração & dosagem , Gorduras na Dieta/farmacologia , Mel , Incretinas/sangue , Inflamação/metabolismo , Masculino , Proteínas de Membrana Transportadoras/sangue , Proteínas Mitocondriais , Transportadores de Ácidos Monocarboxílicos , NF-kappa B/metabolismo , Obesidade/etiologia , Obesidade/metabolismo , PPAR gama/sangue , Ratos Wistar , Proteínas Carreadoras de Solutos , Stevia , Sacarose/análogos & derivados , Sacarose/farmacologia , Paladar , Transaminases , Proteína Desacopladora 1/sangue
18.
Cell Tissue Res ; 377(2): 167-176, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30868340

RESUMO

The solute carrier (SLC) group of membrane transport proteins includes about 400 members organized into more than 50 families. The SLC family that comprises nucleoside-sugar transporters is referred to as SLC35. One of the members of this family is SLC35F1. The function of SLC35F1 is still unknown; however, recent studies demonstrated that SLC35F1 mRNA is highly expressed in the brain and in the kidney. Therefore, we examine the distribution of Slc35f1 protein in the murine forebrain using immunohistochemistry. We could demonstrate that Slc35f1 is highly expressed in the adult mouse brain in a variety of different brain structures, including the cortex, hippocampus, amygdala, thalamus, basal ganglia, and hypothalamus. To examine the possible roles of Slc35f1 and its subcellular localization, we used an in vitro glioblastoma cell line expressing Slc35f1. Co-labeling experiments were performed to reveal the subcellular localization of Slc35f1. Our results indicate that Slc35f1 neither co-localizes with markers for the Golgi apparatus nor with markers for the endoplasmic reticulum. Time-lapse microscopy of living cells revealed that Slc35f1-positive structures are highly dynamic and resemble vesicles. Using super-resolution microscopy, these Slc35f1-positive spots clearly co-localize with the recycling endosome marker Rab11.


Assuntos
Encéfalo/metabolismo , Encéfalo/ultraestrutura , Proteínas Carreadoras de Solutos/metabolismo , Animais , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Células Tumorais Cultivadas , Proteínas rab de Ligação ao GTP/metabolismo
19.
Mol Pharm ; 16(5): 2069-2082, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-30916978

RESUMO

Huntington's disease (HD) is a neurodegenerative disease caused by polyglutamine expansion in the huntingtin protein. For drug candidates targeting HD, the ability to cross the blood-brain barrier (BBB) and reach the site of action in the central nervous system (CNS) is crucial for achieving pharmacological activity. To assess the permeability of selected compounds across the BBB, we utilized a two-dimensional model composed of primary porcine brain endothelial cells and rat astrocytes. Our objective was to use this in vitro model to rank and prioritize compounds for in vivo pharmacokinetic and brain penetration studies. The model was first characterized using a set of validation markers chosen based on their functional importance at the BBB. It was shown to fulfill the major BBB characteristics, including functional tight junctions, high transendothelial electrical resistance, expression, and activity of influx and efflux transporters. The in vitro permeability of 54 structurally diverse known compounds was determined and shown to have a good correlation with the in situ brain perfusion data in rodents. We used this model to investigate the BBB permeability of a series of new HD compounds from different chemical classes, and we found a good correlation with in vivo brain permeation, demonstrating the usefulness of the in vitro model for optimizing CNS drug properties and for guiding the selection of lead compounds in a drug discovery setting.


Assuntos
Barreira Hematoencefálica/metabolismo , Fármacos do Sistema Nervoso Central/uso terapêutico , Descoberta de Drogas/métodos , Doença de Huntington/tratamento farmacológico , Modelos Biológicos , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Astrócitos/metabolismo , Permeabilidade Capilar/fisiologia , Células Cultivadas , Córtex Cerebral/citologia , Técnicas de Cocultura , Impedância Elétrica , Células Endoteliais/metabolismo , Permeabilidade , Ratos , Ratos Sprague-Dawley , Proteínas Carreadoras de Solutos/metabolismo , Suínos , Junções Íntimas/metabolismo
20.
Semin Nephrol ; 39(2): 159-175, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30827339

RESUMO

The kidney plays a critical role in the elimination of many xenobiotics, and drug-induced kidney injury is a risk factor in drug discovery and development. In addition, accumulation of nephrotoxic compounds, a process often controlled by xenobiotic transporters, is often a prerequisite to kidney injury. Such adverse events are dependent on many transporters, particularly those in the solute carrier and adenosine triphosphate-binding cassette superfamilies. This review details the current understanding of how kidney transporters contribute to toxic outcomes and highlights critical knowledge gaps regarding species differences that account for some lack of predictivity between preclinical animal models and human beings. The basic classification, physiological roles, and species differences of solute carrier and adenosine triphosphate-binding cassette transporters is reviewed, along with mechanistic details for drug-induced kidney injury involving transporters. The use of preclinical data (in vitro and in vivo), clinical data, and conventional as well as emerging tools for studying kidney transporter function are summarized. Finally, we highlight some challenges and opportunities to improve experimental approaches to support preclinical and clinical studies of kidney transporters and their role in nephrotoxicity.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Lesão Renal Aguda/induzido quimicamente , Insuficiência Renal Crônica/induzido quimicamente , Proteínas Carreadoras de Solutos/metabolismo , Lesão Renal Aguda/metabolismo , Humanos , Túbulos Renais/metabolismo , Insuficiência Renal Crônica/metabolismo , Xenobióticos
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