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Mukhtar I, Anwar H, Iftikhar A, Hashem HE, Ali Q, Siddique F. Human targeted phenobarbital presents a poor substrate of gut microbiome deciphering new drug targets beyond pharmacokinetic curbs. BMC Pharmacol Toxicol 2022; 23:85. [DOI: 10.1186/s40360-022-00618-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 09/27/2022] [Indexed: 11/15/2022] Open
Abstract
Abstract
Background
The gut microbiome, a new organ of the body, can potentially alter the pharmacokinetics of orally administered drugs through microbial enzymes. However, absorption of orally administered non-antibiotic drugs by the gut microbiome, during drug-microbiome interaction, is barely addressed. Structural homology studies confirm similar membrane transport proteins in gut epithelial cells and the gut microbiome of the host that may compete for drug substrates with the host itself for its absorbance. Therefore, it is hypothesized that orally administered human targeted phenobarbital may interact and/or be uptake by the gut microbiome during its transit through the small intestine.
Methods
In the current in vivo study, thirty-six male Wistar albino rats were divided into six groups including one control and 5 treatment groups, each having an equal number of rats (n = 6). Phenobarbital was administered orally (single dose of 15 mg/kg bw) to treatment groups. Animals were subsequently sacrificed to harvest microbial mass pallets residing in the small intestine after 2, 3, 4, 5, and 6 h of phenobarbital administration. Phenobarbital absorbance by the microbiome in the microbial lysate was estimated through RP-HPLC–UV at a wavelength of 207 nm.
Results
Maximum phenobarbital absorbance (149.0 ± 5.93 µg) and drug absorbance per milligram of microbial mass (1.19 ± 0.05 µg) were found significantly higher at 4 h of post-administration in comparison to other groups. Percent dose recovery of phenobarbital was 5.73 ± 0.19% at 4 h while the maximum intestinal transit time was 5 h till the drug was absorbed by the microbes. Such results pronounce the idea of the existence of structural homology between membrane transporters of the gut microbiome and intestinal enterocytes of the host that may competitively absorb orally administered phenobarbital during transit in the small intestine. The docking studies revealed that the phenobarbital is a poor substrate for the gut microbiome.
Conclusion
Gut microbiome may competitively absorb the non-antibiotics such as phenobarbital as novel substrates due to the presence of structurally homologous transporting proteins as in enterocytes. This phenomenon suggests the microbiome as a potential candidate that can significantly alter the pharmacokinetics of drugs.
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Vacca F, Gomes AS, Murashita K, Cinquetti R, Roseti C, Barca A, Rønnestad I, Verri T, Bossi E. Functional characterization of Atlantic salmon (Salmo salar L.) PepT2 transporters. J Physiol 2022; 600:2377-2400. [PMID: 35413133 PMCID: PMC9321897 DOI: 10.1113/jp282781] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/16/2022] [Indexed: 11/24/2022] Open
Abstract
Abstract The high‐affinity/low‐capacity system Slc15a2 (PepT2) is responsible for the reuptake of di/tripeptides from the renal proximal tubule, but it also operates in many other tissues and organs. Information regarding PepT2 in teleost fish is limited and, to date, functional data are available from the zebrafish (Danio rerio) only. Here, we report the identification of two slc15a2 genes in the Atlantic salmon (Salmo salar) genome, namely slc15a2a and slc15a2b. The two encoded PepT2 proteins share 87% identity and resemble both structurally and functionally the canonical vertebrate PepT2 system. The mRNA tissue distribution analyses reveal a widespread distribution of slc15a2a transcripts, being more abundant in the brain and gills, while slc15a2b transcripts are mainly expressed in the kidney and the distal part of the gastrointestinal tract. The function of the two transporters was investigated by heterologous expression in Xenopus laevis oocytes and two‐electrode voltage‐clamp recordings of transport and presteady‐state currents. Both PepT2a and PepT2b in the presence of Gly‐Gln elicit pH‐dependent and Na+ independent inward currents. The biophysical and kinetic analysis of the recorded currents defined the transport properties, confirming that the two Atlantic salmon PepT2 proteins behave as high‐affinity/low‐capacity transporters. The recent structures and the previous kinetic schemes of rat and human PepT2 qualitatively account for the characteristics of the two Atlantic salmon proteins. This study is the first to report on the functional expression of two PepT2‐type transporters that operate in the same vertebrate organism as a result of (a) gene duplication process(es). Key points Two slc15a2‐type genes, slc15a2a and slc15a2b coding for PepT2‐type peptide transporters were found in the Atlantic salmon. slc15a2a
transcripts, widely distributed in the fish tissues, are abundant in the brain and gills, while slc15a2b transcripts are mainly expressed in the kidney and distal gastrointestinal tract. Amino acids involved in vertebrate Slc15 transport function are conserved in PepT2a and PepT2b proteins. Detailed kinetic analysis indicates that both PepT2a and PepT2b operate as high‐affinity transporters. The kinetic schemes and structures proposed for the mammalian models of PepT2 are suitable to explain the function of the two Atlantic salmon transporters.
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Affiliation(s)
- Francesca Vacca
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, Varese, I-21100, Italy
| | - Ana S Gomes
- Department of Biological Sciences, University of Bergen, Po. Box 7803, Bergen, NO-5020, Norway
| | - Koji Murashita
- Research Center for Aquaculture Systems, National Research Institute of Aquaculture, Japan Fisheries Research and Education Agency, Minami-ise, Mie, 516-0193, Japan
| | - Raffella Cinquetti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, Varese, I-21100, Italy
| | - Cristina Roseti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, Varese, I-21100, Italy
| | - Amilcare Barca
- Laboratory of Applied Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, via Provinciale Lecce-Monteroni, Lecce, I-73100, Italy
| | - Ivar Rønnestad
- Department of Biological Sciences, University of Bergen, Po. Box 7803, Bergen, NO-5020, Norway
| | - Tiziano Verri
- Laboratory of Applied Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, via Provinciale Lecce-Monteroni, Lecce, I-73100, Italy
| | - Elena Bossi
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, Varese, I-21100, Italy
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3
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Stauffer M, Jeckelmann JM, Ilgü H, Ucurum Z, Boggavarapu R, Fotiadis D. Peptide transporter structure reveals binding and action mechanism of a potent PEPT1 and PEPT2 inhibitor. Commun Chem 2022; 5:23. [PMID: 36697632 PMCID: PMC9814568 DOI: 10.1038/s42004-022-00636-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/27/2022] [Indexed: 01/28/2023] Open
Abstract
Inhibitors for membrane transporters have been shown to be indispensable as drugs and tool compounds. The proton-dependent oligopeptide transporters PEPT1 and PEPT2 from the SLC15 family play important roles in human and mammalian physiology. With Lys[Z(NO2)]-Val (LZNV), a modified Lys-Val dipeptide, a potent transport inhibitor for PEPT1 and PEPT2 is available. Here we present the crystal structure of the peptide transporter YePEPT in complex with LZNV. The structure revealed the molecular interactions for inhibitor binding and a previously undescribed mostly hydrophobic pocket, the PZ pocket, involved in interaction with LZNV. Comparison with a here determined ligand-free structure of the transporter unveiled that the initially absent PZ pocket emerges through conformational changes upon inhibitor binding. The provided biochemical and structural information constitutes an important framework for the mechanistic understanding of inhibitor binding and action in proton-dependent oligopeptide transporters.
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Affiliation(s)
- Mirko Stauffer
- grid.5734.50000 0001 0726 5157Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Jean-Marc Jeckelmann
- grid.5734.50000 0001 0726 5157Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Hüseyin Ilgü
- grid.5734.50000 0001 0726 5157Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Zöhre Ucurum
- grid.5734.50000 0001 0726 5157Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
| | - Rajendra Boggavarapu
- grid.5734.50000 0001 0726 5157Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland ,grid.67105.350000 0001 2164 3847Present Address: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH USA
| | - Dimitrios Fotiadis
- grid.5734.50000 0001 0726 5157Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bern, Switzerland
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4
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Zhu J, Mou Y, Ye S, Hu H, Wang R, Yang Q, Hu Y. Identification of a Six-Gene SLC Family Signature With Prognostic Value in Patients With Lung Adenocarcinoma. Front Cell Dev Biol 2022; 9:803198. [PMID: 34977043 PMCID: PMC8714960 DOI: 10.3389/fcell.2021.803198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/30/2021] [Indexed: 12/17/2022] Open
Abstract
Given the importance of solute carrier (SLC) proteins in maintaining cellular metabolic homeostasis and that their dysregulation contributes to cancer progression, here we constructed a robust SLC family signature for lung adenocarcinoma (LUAD) patient stratification. Transcriptomic profiles and relevant clinical information of LUAD patients were downloaded from the TCGA and GEO databases. SLC family genes differentially expressed between LUAD tissues and adjacent normal tissues were identified using limma in R. Of these, prognosis-related SLC family genes were further screened out and used to construct a novel SLC family-based signature in the training cohort. The accuracy of the prognostic signature was assessed in the testing cohort, the entire cohort, and the external GSE72094 cohort. Correlations between the prognostic signature and the tumor immune microenvironment and immune cell infiltrates were further explored. We found that seventy percent of SLC family genes (279/397) were differentially expressed between LUAC tissues and adjacent normal. Twenty-six genes with p-values < 0.05 in univariate Cox regression analysis and Kaplan-Meier survival analysis were regarded as prognosis-related SLC family genes, six of which were used to construct a prognostic signature for patient classification into high- and low-risk groups. Kaplan-Meier survival analysis in all internal and external cohorts revealed a better overall survival for patients in the low-risk group than those in the high-risk group. Univariate and multivariate Cox regression analyses indicated that the derived risk score was an independent prognostic factor for LUAD patients. Moreover, a nomogram based on the six-gene signature and clinicopathological factors was developed for clinical application. High-risk patients had lower stromal, immune, and ESTIMATE scores and higher tumor purities than those in the low-risk group. The proportions of infiltrating naive CD4 T cells, activated memory CD4 T cells, M0 macrophages, resting dendritic cells, resting mast cells, activated mast cells, and eosinophils were significantly different between the high- and low-risk prognostic groups. In all, the six-gene SLC family signature is of satisfactory accuracy and generalizability for predicting overall survival in patients with LUAD. Furthermore, this prognostics signature is related to tumor immune status and distinct immune cell infiltrates in the tumor microenvironment.
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Affiliation(s)
- Jing Zhu
- Department of Respiratory and Critical Care Medicine, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yong Mou
- Department of Respiratory and Critical Care Medicine, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shenglan Ye
- Department of Respiratory and Critical Care Medicine, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hongling Hu
- Department of Respiratory and Critical Care Medicine, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Rujuan Wang
- Department of Respiratory and Critical Care Medicine, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qing Yang
- Department of Respiratory and Critical Care Medicine, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yi Hu
- Department of Respiratory and Critical Care Medicine, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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5
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Prabhala BK, Rahman M, Nour-Eldin HH, Jørgensen FS, Mirza O. PTR2/POT/NPF transporters: what makes them tick? ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2020; 123:219-240. [PMID: 33485485 DOI: 10.1016/bs.apcsb.2020.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PTR2/POT/NPF are a family of primarily proton coupled transporters that belong to the major facilitator super family and are found across most kingdoms of life. They are involved in uptake of nutrients, hormones, ions and several orally administered drug molecules. A wealth of structural and functional data is available for this family; the similarity between the protein structural features have been discussed and investigated in detail on several occasions, however there are no reports on the unification of substrate information. In order to fill this gap, we have collected information about substrates across the entire PTR2/POT/NPF family in order to provide key insights into what makes a molecule a substrate and whether there are common features among confirmed substrates. This review will be of particular interest for researchers in the field trying to probe the mechanisms responsible for the different selectivity of these transporters at a molecular resolution, and to design novel substrates.
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Affiliation(s)
- Bala K Prabhala
- Institute of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Moazur Rahman
- School of Biological Sciences, University of the Punjab, Lahore, Punjab, Pakistan; Drug Discovery and Structural Biology Group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Punjab, Pakistan
| | - Hussam H Nour-Eldin
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Flemming Steen Jørgensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Osman Mirza
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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6
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Li Y, Yuan S, Yong X, zhao T, Liu J. Research progress on small peptides in Chinese Baijiu. J Funct Foods 2020. [DOI: 10.1016/j.jff.2020.104081] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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7
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Zheng S, Lin X, Wu H, Zhao C, Xu H. Synthesis, bioactivities and phloem uptake of dipeptide-chlorantraniliprole derivatives. BMC Chem 2020; 14:22. [PMID: 32259134 PMCID: PMC7106865 DOI: 10.1186/s13065-020-00673-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 03/09/2020] [Indexed: 11/10/2022] Open
Abstract
Phloem systemicity is a desirable property for insecticides to control sucking insects. However, the development of phloem systemic insecticides is challenging. One possible strategy is to link existed insecticides with endogenous substances so that the resulting conjugates can be transported by specific transporters into the phloem. In this study, novel dipeptide promoieties were introduced into chlorantraniliprole, which is an efficient and broad-spectrum anthranilic diamide insecticide without phloem mobility. Twenty-two new dipeptide-chlorantraniliprole conjugates have been synthesized. Systemic tests showed that all conjugates exhibited phloem mobility in Ricinus communis. In particular, compound 4g with alanyl-alanine dipeptide fragment was able to accumulate in phloem sap (114.49 ± 11.10 μM) in the form of its hydrolysis product 5g. Results of bioassay showed that conjugates 4g and 5g were able to exhibit comparable insecticidal activity against Plutella xylostella L. and Spodoptera exigua compared to its parent compound chlorantraniliprole. This work demonstrated that the dipeptide structures were able to contribute to the improvement of the uptake and phloem mobility of chlorantraniliprole, and two phloem mobile conjugates with satisfactory in vivo insecticidal effect was obtained as new candidates for high-efficient insecticides.
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Affiliation(s)
- Shijie Zheng
- 1State Key Laboratory for Conservation and Utilization of Subtropical Argo-Bioresources, South China Agricultural University, Guangzhou, Guangdong China.,2Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, 510642 China
| | - Xiaomin Lin
- 1State Key Laboratory for Conservation and Utilization of Subtropical Argo-Bioresources, South China Agricultural University, Guangzhou, Guangdong China.,2Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, 510642 China
| | - Hanxiang Wu
- 1State Key Laboratory for Conservation and Utilization of Subtropical Argo-Bioresources, South China Agricultural University, Guangzhou, Guangdong China.,2Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, 510642 China
| | - Chen Zhao
- 1State Key Laboratory for Conservation and Utilization of Subtropical Argo-Bioresources, South China Agricultural University, Guangzhou, Guangdong China.,2Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, 510642 China
| | - Hanhong Xu
- 1State Key Laboratory for Conservation and Utilization of Subtropical Argo-Bioresources, South China Agricultural University, Guangzhou, Guangdong China.,2Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, South China Agricultural University, Guangzhou, 510642 China
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8
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Solute carrier transporters: the metabolic gatekeepers of immune cells. Acta Pharm Sin B 2020; 10:61-78. [PMID: 31993307 PMCID: PMC6977534 DOI: 10.1016/j.apsb.2019.12.006] [Citation(s) in RCA: 107] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/29/2019] [Accepted: 10/31/2019] [Indexed: 02/06/2023] Open
Abstract
Solute carrier (SLC) transporters meditate many essential physiological functions, including nutrient uptake, ion influx/efflux, and waste disposal. In its protective role against tumors and infections, the mammalian immune system coordinates complex signals to support the proliferation, differentiation, and effector function of individual cell subsets. Recent research in this area has yielded surprising findings on the roles of solute carrier transporters, which were discovered to regulate lymphocyte signaling and control their differentiation, function, and fate by modulating diverse metabolic pathways and balanced levels of different metabolites. In this review, we present current information mainly on glucose transporters, amino-acid transporters, and metal ion transporters, which are critically important for mediating immune cell homeostasis in many different pathological conditions.
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Key Words
- 3-PG, 3-phosphoglyceric acid
- ABC, ATP-binding cassette
- AIF, apoptosis-inducing factor
- AP-1, activator protein 1
- ASCT2, alanine serine and cysteine transporter system 2
- ATP, adenosine triphosphate
- BCR, B cell receptor
- BMDMs, bone marrow-derived macrophages
- CD45R, a receptor-type protein tyrosine phosphatase
- CTL, cytotoxic T lymphocytes
- DC, dendritic cells
- EAATs, excitatory amino acid transporters
- ER, endoplasmic reticulum
- ERRα, estrogen related receptor alpha
- FFA, free fatty acids
- G-6-P, glucose 6-phosphate
- GLUT, glucose transporters
- GSH, glutathione
- Glucose
- Glutamine
- HIF-1α, hypoxia-inducible factor 1-alpha
- HIV-1, human immunodeficiency virus type 1
- Hk1, hexokinase-1
- IFNβ, interferon beta
- IFNγ, interferon gamma
- IKK, IκB kinase
- IKKβ, IκB kinase beta subunit
- IL, interleukin
- LDHA, lactate dehydrogenase A
- LPS, lipopolysaccharide
- Lymphocytes
- Lyn, tyrosine-protein kinase
- MAPK, mitogen-activated protein kinase
- MCT, monocarboxylate transporters
- MS, multiple sclerosis
- Metal ion
- NADPH, nicotinamide adenine dinucleotide phosphate
- NF-κB, nuclear factor kappa-light-chain-enhancer of activated B cells
- NO, nitric oxide
- NOD2, nucleotide-binding oligomerization domain containing 2
- PEG2, prostaglandin E2
- PI-3K/AKT, phosphatidylinositol-3-OH kinase/serine–threonine kinase
- PPP, pentose phosphate pathway
- Pfk, phosphofructokinase
- RA, rheumatoid arthritis
- RLR, RIG-I-like receptor
- ROS, reactive oxygen species
- SLC, solute carrier
- SLE, systemic lupus erythematosus
- SNAT, sodium-coupled neutral amino acid transporters
- STAT, signal transducers and activators of transcription
- Solute carrier
- TAMs, tumor-associated macrophages
- TCA, tricarboxylic acid
- TCR, T cell receptor
- TLR, toll-like receptor
- TNF, tumor necrosis factor
- TRPM7, transient receptor potential cation channel subfamily M member 7
- Teffs, effector T cells
- Th1/2/17, type 1/2/17 helper T cells
- Tregs, regulatory T cells
- VEGF, vascular endothelial growth factor
- ZIP, zrt/irt-like proteins
- iNOS, inducible nitric oxide synthase
- iTregs, induced regulatory T cells
- mTORC1, mammalian target of rapamycin complex 1
- α-KG, α-ketoglutaric acid
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9
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Wulff N, Ernst HA, Jørgensen ME, Lambertz S, Maierhofer T, Belew ZM, Crocoll C, Motawia MS, Geiger D, Jørgensen FS, Mirza O, Nour-Eldin HH. An Optimized Screen Reduces the Number of GA Transporters and Provides Insights Into Nitrate Transporter 1/Peptide Transporter Family Substrate Determinants. FRONTIERS IN PLANT SCIENCE 2019; 10:1106. [PMID: 31632416 PMCID: PMC6785635 DOI: 10.3389/fpls.2019.01106] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/13/2019] [Indexed: 05/17/2023]
Abstract
Based on recent in vitro data, a relatively large number of the plant nitrate transporter 1/peptide transporter family (NPF) proteins have been suggested to function as gibberellic acid (GA) transporters. Most GA transporting NPF proteins also appear to transport other structurally unrelated phytohormones or metabolites. Several of the GAs used in previous in vitro assays are membrane permeable weak organic acids whose movement across membranes are influenced by the pH-sensitive ion-trap mechanism. Moreover, a large proportion of in vitro GA transport activities have been demonstrated indirectly via long-term yeast-based GA-dependent growth assays that are limited to detecting transport of bioactive GAs. Thus, there is a need for an optimized transport assay for identifying and characterizing GA transport. Here, we develop an improved transport assay in Xenopus laevis oocytes, wherein we directly measure movement of six different GAs across oocyte membranes over short time. We show that membrane permeability of GAs in oocytes can be predicted based on number of oxygen atoms and that several GAs do not diffuse over membranes regardless of changes in pH values. In addition, we show that small changes in internal cellular pH can result in strongly altered distribution of membrane permeable phytohormones. This prompts caution when interpreting heterologous transport activities. We use our transport assay to screen all Arabidopsis thaliana NPF proteins for transport activity towards six GAs (two membrane permeable and four non-permeable). The results presented here, significantly reduce the number of bona fide NPF GA transporters in Arabidopsis and narrow the activity to fewer subclades within the family. Furthermore, to gain first insight into the molecular determinants of substrate specificities toward organic molecules transported in the NPF, we charted all surface exposed amino acid residues in the substrate-binding cavity and correlated them to GA transport. This analysis suggests distinct residues within the substrate-binding cavity that are shared between GA transporting NPF proteins; the potential roles of these residues in determining substrate specificity are discussed.
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Affiliation(s)
- Nikolai Wulff
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | | | - Morten Egevang Jørgensen
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- Julius-von-Sachs-Institute, Molecular Plant Physiology and Biophysics, University Würzburg, Würzburg, Germany
- Carlsberg Research Laboratory, Copenhagen, Denmark
| | - Sophie Lambertz
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Tobias Maierhofer
- Julius-von-Sachs-Institute, Molecular Plant Physiology and Biophysics, University Würzburg, Würzburg, Germany
| | - Zeinu Mussa Belew
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Christoph Crocoll
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Mohammed Saddik Motawia
- Center for Plant Plasticity, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Dietmar Geiger
- Julius-von-Sachs-Institute, Molecular Plant Physiology and Biophysics, University Würzburg, Würzburg, Germany
| | | | - Osman Mirza
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Hussam Hassan Nour-Eldin
- DynaMo Center, Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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10
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Dong A, Liu S, Li Y. Gap Junctions in the Nervous System: Probing Functional Connections Using New Imaging Approaches. Front Cell Neurosci 2018; 12:320. [PMID: 30283305 PMCID: PMC6156252 DOI: 10.3389/fncel.2018.00320] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 09/03/2018] [Indexed: 11/13/2022] Open
Abstract
Gap junctions are channels that physically connect adjacent cells, mediating the rapid exchange of small molecules, and playing an essential role in a wide range of physiological processes in nearly every system in the body, including the nervous system. Thus, altered function of gap junctions has been linked with a plethora of diseases and pathological conditions. Being able to measure and characterize the distribution, function, and regulation of gap junctions in intact tissue is therefore essential for understanding the physiological and pathophysiological roles that gap junctions play. In recent decades, several robust in vitro and in vivo methods have been developed for detecting and characterizing gap junctions. Here, we review the currently available methods with respect to invasiveness, signal-to-noise ratio, temporal resolution and others, highlighting the recently developed chemical tracers and hybrid imaging systems that use novel chemical compounds and/or genetically encoded enzymes, transporters, channels, and fluorescent proteins in order to map gap junctions. Finally, we discuss possible avenues for further improving existing techniques in order to achieve highly sensitive, cell type-specific, non-invasive measures of in vivo gap junction function with high throughput and high spatiotemporal resolution.
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Affiliation(s)
- Ao Dong
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Simin Liu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.,PKU-IDG/McGovern Institute for Brain Research, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Beijing, China
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11
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Li L, Weng Y, Wang W, Bai M, Lei H, Zhou H, Jiang H. Multiple organic cation transporters contribute to the renal transport of sulpiride. Biopharm Drug Dispos 2017; 38:526-534. [PMID: 28926871 DOI: 10.1002/bdd.2104] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 08/29/2017] [Accepted: 09/07/2017] [Indexed: 01/01/2023]
Abstract
Sulpiride, a selective dopamine D2 receptor blocker, is used widely for the treatment of schizophrenia, depression and gastric/duodenal ulcers. Because the great majority of sulpiride is positively charged at physiological pH 7.4, and ~70% of the dose recovered in urine is in the unchanged form after human intravenous administration of sulpiride, it is believed that transporters play an important role in the renal excretion of sulpiride. The aim of the present study was to explore which transporters contribute to the renal disposition of sulpiride. The results demonstrated that sulpiride was a substrate of human carnitine/organic cation transporter 1 (hOCTN1) and 2 (hOCTN2), human organic cation transporter 2 (hOCT2), human multidrug and toxin efflux extrusion protein 1 (hMATE1) and 2-K (hMATE2-K). Sulpiride accumulation from the basolateral (BL) to the apical (AP) side in MDCK-hOCT2/pcDNA3.1 cell monolayers was much greater than that in MDCK-hOCT2/hMATE1 cells, and cimetidine dramatically reduced the intracellular accumulation of sulpiride from BL to AP. In addition, the accumulation of sulpiride in mouse primary renal tubular cells (mPRTCs) was markedly reduced by inhibitors of Oct2 and Octns. The results implied that OCTN1, OCTN2, OCT2, MATE1 and MATE2-K probably contributed to the renal transfer of sulpiride, in which OCT2 mediated the uptake of sulpiride from the bloodstream to the proximal tubular cells, while MATEs contributed to the sulpiride efflux from the proximal tubular cells to the renal lumen, and OCTNs participated in both renal secretion and reabsorption.
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Affiliation(s)
- Liping Li
- Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yayun Weng
- Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Wei Wang
- Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Mengru Bai
- Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hongmei Lei
- Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hui Zhou
- Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Huidi Jiang
- Laboratory of Pharmaceutical Analysis and Drug Metabolism, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
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12
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Qiu D, Hu R, Li Y, Zhang M. Aromatic dipeptide Trp-Ala can be transported by Arabidopsis peptide transporters AtPTR1 and AtPTR5. Channels (Austin) 2017; 11:383-387. [PMID: 28418760 DOI: 10.1080/19336950.2017.1319024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Dipeptides with an aromatic residue at the N-terminal position induced lower inward currents or blocked leak currents in Xenopus oocytes expressing the proton-coupled peptide transporter AtPTR1 or AtPTR5 of Arabidopsis thaliana compared with dipeptides with an aromatic residue at the C-terminal position. Here, AtPTR1 and AtPTR5 were expressed in a yeast mutant of peptide transporter (ptr2) with tryptophan auxotrophy. Growth assays showed that Trp-Ala could be transported by both AtPTR1 and AtPTR5 as efficiently as Ala-Trp. Our data suggested that the previous finding in Xenopus oocytes might be an artifact of heterologous expression, and that AtPTR1 and AtPTR5 expressed in yeast could transport dipeptides with an aromatic residue at the N-terminal position.
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Affiliation(s)
- Diyang Qiu
- a Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement , Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences , Guangzhou , China.,b University of Chinese Academy of Sciences , Beijing , China
| | - Rui Hu
- a Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement , Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences , Guangzhou , China.,b University of Chinese Academy of Sciences , Beijing , China
| | - Ying Li
- c College of Horticulture and Landscape Architecture , Zhongkai University of Agriculture and Engineering , Guangzhou , China
| | - Mingyong Zhang
- a Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement , Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences , Guangzhou , China
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13
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Zhang C, Zhang Y, Wang Z, Chen S, Luo Y. Production and identification of antioxidant and angiotensin-converting enzyme inhibition and dipeptidyl peptidase IV inhibitory peptides from bighead carp (Hypophthalmichthys nobilis) muscle hydrolysate. J Funct Foods 2017. [DOI: 10.1016/j.jff.2017.05.032] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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14
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Hong M. Biochemical studies on the structure-function relationship of major drug transporters in the ATP-binding cassette family and solute carrier family. Adv Drug Deliv Rev 2017; 116:3-20. [PMID: 27317853 DOI: 10.1016/j.addr.2016.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 12/21/2022]
Abstract
Human drug transporters often play key roles in determining drug accumulation within cells. Their activities are often directly related to therapeutic efficacy, drug toxicity as well as drug-drug interactions. However, the progress for interpretation of their crystal structures is relatively slow. Hence, conventional biochemical studies together with computer modeling became useful manners to reveal essential structures of these membrane proteins. Over the years, quite a few structure-function relationship information had been obtained for members of the two major transporter families: the ATP-binding cassette family and the solute carrier family. Critical structural features of drug transporters include transmembrane domains, post-translational modification sites and domains for cell surface assembly and protein-protein interactions. Alterations at these important sites may affect protein stability, trafficking to the plasma membrane and/or ability of transporters to interact with substrates.
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15
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Symmetry and Structure in the POT Family of Proton Coupled Peptide Transporters. Symmetry (Basel) 2017. [DOI: 10.3390/sym9060085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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16
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Garai P, Chandra K, Chakravortty D. Bacterial peptide transporters: Messengers of nutrition to virulence. Virulence 2016; 8:297-309. [PMID: 27589415 DOI: 10.1080/21505594.2016.1221025] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Bacteria possess numerous peptide transporters for importing peptides as nutrients. However, these peptide transporters are now consistently reported to play a role in the virulence of various bacterial pathogens. Their ability to transport peptides has implications in antibacterial therapy as well. Therefore, it would be instrumental to have complete knowledge about the role of peptide transporters in mediating this cross connection between metabolism and pathogenesis. Studies on various peptide transporters in bacterial pathogens have improved our understanding of this field. In this review, we have given an overview of the functioning of bacterial peptide transporters and their contribution in virulence of major bacterial pathogens.
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Affiliation(s)
- Preeti Garai
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | - Kasturi Chandra
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | - Dipshikha Chakravortty
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
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17
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Abstract
Oligopeptide transporters serve important functions in nutrition and pharmacology. In particular, these transporters help maintain the homeostasis of peptides. The peptide-transporter PEPT2 is a high-affinity and low-capacity type oligopeptide transporter from the proton-coupled oligopeptide transporter family. PEPT2 has recently received attention because of its potential application in targeted drug delivery. PEPT2 is widely distributed in kidney, central nervous system, and lung of organisms. In general, all dipeptides, tripeptides, and peptide-like drugs such as β-lactam antibiotics and angiotensin-converting enzyme inhibitors could be mediated and transported as a substrate of PEPT2. The design of many extant drugs and prodrugs is based on the substrate structure of PEPT2 to accelerate absorption via peptide transporters. Thus, this paper summarizes the substrate features of PEPT2 to promote the rational design of drugs and prodrugs that target peptide transporters.
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Affiliation(s)
- Dongxin Zhao
- School of Chemistry and Chemical Engineering, Henan University of Technology
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18
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Samsudin F, Parker JL, Sansom MSP, Newstead S, Fowler PW. Accurate Prediction of Ligand Affinities for a Proton-Dependent Oligopeptide Transporter. Cell Chem Biol 2016; 23:299-309. [PMID: 27028887 PMCID: PMC4760754 DOI: 10.1016/j.chembiol.2015.11.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/22/2015] [Accepted: 11/04/2015] [Indexed: 12/04/2022]
Abstract
Membrane transporters are critical modulators of drug pharmacokinetics, efficacy, and safety. One example is the proton-dependent oligopeptide transporter PepT1, also known as SLC15A1, which is responsible for the uptake of the β-lactam antibiotics and various peptide-based prodrugs. In this study, we modeled the binding of various peptides to a bacterial homolog, PepTSt, and evaluated a range of computational methods for predicting the free energy of binding. Our results show that a hybrid approach (endpoint methods to classify peptides into good and poor binders and a theoretically exact method for refinement) is able to accurately predict affinities, which we validated using proteoliposome transport assays. Applying the method to a homology model of PepT1 suggests that the approach requires a high-quality structure to be accurate. Our study provides a blueprint for extending these computational methodologies to other pharmaceutically important transporter families. A hierarchical computational approach determines ligand affinities to transporters Lysine-containing dipeptides proposed to bind vertically like a tripeptide Experimental structures are vital for the accurate prediction of affinities A model of prodrug interactions to human PepT1 is suggested
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Affiliation(s)
- Firdaus Samsudin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Joanne L Parker
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
| | - Philip W Fowler
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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19
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Qiao M, Sanes JR. Genetic Method for Labeling Electrically Coupled Cells: Application to Retina. Front Mol Neurosci 2016; 8:81. [PMID: 26778956 PMCID: PMC4703850 DOI: 10.3389/fnmol.2015.00081] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 12/11/2015] [Indexed: 01/08/2023] Open
Abstract
Understanding how the nervous system functions requires mapping synaptic connections between neurons. Several methods are available for imaging neurons connected by chemical synapses, but few enable marking neurons connected by electrical synapses. Here, we demonstrate that a peptide transporter, Pept2, can be used for this purpose. Pept2 transports a gap junction-permeable fluorophore-coupled dipeptide, beta-alanine-lysine-N-7-amino-4-methyl coumarin-3-acid (βALA). Cre-dependent expression of pept2 in specific neurons followed by incubation in βALA labeled electrically coupled synaptic partners. Using this method, we analyze light-dependent modulation of electrical connectivity among retinal horizontal cells.
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Affiliation(s)
- Mu Qiao
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge MA, USA
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge MA, USA
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20
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Lu X, Chan T, Xu C, Zhu L, Zhou QT, Roberts KD, Chan HK, Li J, Zhou F. Human oligopeptide transporter 2 (PEPT2) mediates cellular uptake of polymyxins. J Antimicrob Chemother 2015; 71:403-12. [PMID: 26494147 DOI: 10.1093/jac/dkv340] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 09/20/2015] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES Polymyxins are a last-line therapy to treat MDR Gram-negative bacterial infections. Nephrotoxicity is the dose-limiting factor for polymyxins and recent studies demonstrated significant accumulation of polymyxins in renal tubular cells. However, little is known about the mechanism of polymyxin uptake into these cells. Oligopeptide transporter 2 (PEPT2) is a solute carrier transporter (SLC) expressed at the apical membrane of renal proximal tubular cells and facilitates drug reabsorption in the kidney. In this study, we examined the role of PEPT2 in polymyxin uptake into renal tubular cells. METHODS We investigated the inhibitory effects of colistin and polymyxin B on the substrate uptake mediated through 15 essential SLCs in overexpressing HEK293 cells. The inhibitory potency of both polymyxins on PEPT2-mediated substrate uptake was measured. Fluorescence imaging was employed to investigate PEPT2-mediated uptake of the polymyxin fluorescent probe MIPS-9541 and a transport assay was conducted with MIPS-9541 and [(3)H]polymyxin B1. RESULTS Colistin and polymyxin B potently inhibited PEPT2-mediated [(3)H]glycyl-sarcosine uptake (IC50 11.4 ± 3.1 and 18.3 ± 4.2 μM, respectively). In contrast, they had no or only mild inhibitory effects on the transport activity of the other 14 SLCs evaluated. MIPS-9541 potently inhibited PEPT2-mediated [(3)H]glycyl-sarcosine uptake (IC50 15.9 μM) and is also a substrate of PEPT2 (Km 74.9 μM). [(3)H]polymyxin B1 was also significantly taken up by PEPT2-expressing cells (Km 87.3 μM). CONCLUSIONS Our study provides the first evidence of PEPT2-mediated uptake of polymyxins and contributes to a better understanding of the accumulation of polymyxins in renal tubular cells.
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Affiliation(s)
- Xiaoxi Lu
- Faculty of Pharmacy, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Ting Chan
- Faculty of Pharmacy, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Chenghao Xu
- Faculty of Pharmacy, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Ling Zhu
- Retinal Therapeutics Research Group, Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia
| | - Qi Tony Zhou
- Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, IN 47907-2091, USA
| | - Kade D Roberts
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC 3052, Australia
| | - Hak-Kim Chan
- Faculty of Pharmacy, The University of Sydney, Camperdown, NSW 2006, Australia
| | - Jian Li
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC 3052, Australia
| | - Fanfan Zhou
- Faculty of Pharmacy, The University of Sydney, Camperdown, NSW 2006, Australia
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21
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Boggavarapu R, Jeckelmann JM, Harder D, Ucurum Z, Fotiadis D. Role of electrostatic interactions for ligand recognition and specificity of peptide transporters. BMC Biol 2015; 13:58. [PMID: 26246134 PMCID: PMC4527243 DOI: 10.1186/s12915-015-0167-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 07/15/2015] [Indexed: 11/10/2022] Open
Abstract
Background Peptide transporters are membrane proteins that mediate the cellular uptake of di- and tripeptides, and of peptidomimetic drugs such as β-lactam antibiotics, antiviral drugs and antineoplastic agents. In spite of their high physiological and pharmaceutical importance, the molecular recognition by these transporters of the amino acid side chains of short peptides and thus the mechanisms for substrate binding and specificity are far from being understood. Results The X-ray crystal structure of the peptide transporter YePEPT from the bacterium Yersinia enterocolitica together with functional studies have unveiled the molecular bases for recognition, binding and specificity of dipeptides with a charged amino acid residue at the N-terminal position. In wild-type YePEPT, the significant specificity for the dipeptides Asp-Ala and Glu-Ala is defined by electrostatic interaction between the in the structure identified positively charged Lys314 and the negatively charged amino acid side chain of these dipeptides. Mutagenesis of Lys314 into the negatively charged residue Glu allowed tuning of the substrate specificity of YePEPT for the positively charged dipeptide Lys-Ala. Importantly, molecular insights acquired from the prokaryotic peptide transporter YePEPT combined with mutagenesis and functional uptake studies with human PEPT1 expressed in Xenopus oocytes also allowed tuning of human PEPT1’s substrate specificity, thus improving our understanding of substrate recognition and specificity of this physiologically and pharmaceutically important peptide transporter. Conclusion This study provides the molecular bases for recognition, binding and specificity of peptide transporters for dipeptides with a charged amino acid residue at the N-terminal position. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0167-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rajendra Boggavarapu
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Jean-Marc Jeckelmann
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Daniel Harder
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Zöhre Ucurum
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland
| | - Dimitrios Fotiadis
- Institute of Biochemistry and Molecular Medicine, and Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland.
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22
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Takano M, Sugimoto N, Ehrhardt C, Yumoto R. Functional Expression of PEPT2 in the Human Distal Lung Epithelial Cell Line NCl-H441. Pharm Res 2015; 32:3916-26. [PMID: 26168863 DOI: 10.1007/s11095-015-1751-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 07/06/2015] [Indexed: 12/31/2022]
Abstract
PURPOSE The peptide transporter PEPT2 is expressed in alveolar type II epithelial cells. So far, however, no appropriate alveolar epithelial cell line for studying PEPT2 function has been known. In this study, we examined the functional expression of PEPT2 in the human distal lung epithelial cell line NCl-H441 (H441). METHODS Expression of PEPT2 mRNA and protein was examined in H441 cells. Transport function of PEPT2 was studied using glycylsarcosine (Gly-Sar) as a substrate. RESULTS Lamellar bodies were well developed in H441 cells and mRNA expression of type II cell markers and PEPT2 increased during time in culture. PEPT2 protein expression was confirmed in H441 cells, but not in A549 cells, by immunostaining and Western blotting. The uptake of Gly-Sar in H441 cells was inhibited by cefadroxil, and the cefadroxil-sensitive uptake was pH-dependent and peaked at pH 6.5. Gly-Sar uptake in H441 cells showed saturation kinetics with a Km value of 112.5 μM. In addition, apical-to-basal, but not basal-to-apical, transport of cephalexin across H441 cell monolayers was sensitive to cefadroxil. CONCLUSIONS PEPT2 is functionally expressed in H441 cells, making the cell line a good in vitro model to study PEPT2 function and its regulation in human distal lung.
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Affiliation(s)
- Mikihisa Takano
- Department of Pharmaceutics and Therapeutics, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan.
| | - Natsumi Sugimoto
- Department of Pharmaceutics and Therapeutics, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
| | - Carsten Ehrhardt
- School of Pharmacy and Pharmaceutical Sciences and Trinity Biomedical Sciences Institute, Trinity College Dublin, Panoz Institute, Dublin 2, Ireland
| | - Ryoko Yumoto
- Department of Pharmaceutics and Therapeutics, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8553, Japan
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Mitsuhashi J, Nakayama T, Narai-Kanayama A. Mechanism of papain-catalyzed synthesis of oligo-tyrosine peptides. Enzyme Microb Technol 2015; 75-76:10-7. [DOI: 10.1016/j.enzmictec.2015.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
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Karau A, Grayson I. Amino acids in human and animal nutrition. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2014; 143:189-228. [PMID: 24676880 DOI: 10.1007/10_2014_269] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Amino acids are key components of human and animal nutrition, both as part of a protein-containing diet, and as supplemented individual products. In the last 10 years there has been a marked move away from the extraction of amino acids from natural products, which has been replaced by efficient fermentation processes using nonanimal carbon sources. Today several amino acids are produced in fermentation plants with capacities of more than 100,000 tonnes to serve the requirements of animal feed and human nutrition. The main fermentative amino acids for animal nutrition are L-lysine, L-threonine, and L-tryptophan. DL-Methionine continues to be manufactured for animal feed use principally by chemical synthesis, and a pharmaceutical grade is manufactured by enzymatic resolution. Amino acids play an important role in medical nutrition, particularly in parenteral nutrition, where there are high purity requirements for infusion grade products. Amino acids are also appearing more often in dietary supplements, initially for performance athletes, but increasingly for the general population. As the understanding of the effects of the individual amino acids on the human metabolism is deepened, more specialized product mixtures are being offered to improve athletic performance and for body-building.
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Affiliation(s)
- Andreas Karau
- Evonik Industries AG, Business Line Health Care, Rodenbacher Chaussee 4, 63457, Hanau-Wolfgang, Germany,
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25
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Lyons JA, Parker JL, Solcan N, Brinth A, Li D, Shah STA, Caffrey M, Newstead S. Structural basis for polyspecificity in the POT family of proton-coupled oligopeptide transporters. EMBO Rep 2014; 15:886-93. [PMID: 24916388 PMCID: PMC4149780 DOI: 10.15252/embr.201338403] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
An enigma in the field of peptide transport is the structural basis for ligand promiscuity, as exemplified by PepT1, the mammalian plasma membrane peptide transporter. Here, we present crystal structures of di- and tripeptide-bound complexes of a bacterial homologue of PepT1, which reveal at least two mechanisms for peptide recognition that operate within a single, centrally located binding site. The dipeptide was orientated laterally in the binding site, whereas the tripeptide revealed an alternative vertical binding mode. The co-crystal structures combined with functional studies reveal that biochemically distinct peptide-binding sites likely operate within the POT/PTR family of proton-coupled symporters and suggest that transport promiscuity has arisen in part through the ability of the binding site to accommodate peptides in multiple orientations for transport.
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Affiliation(s)
- Joseph A Lyons
- Schools of Medicine and Biochemistry & Immunology, Trinity College Dublin, Dublin, Ireland
| | - Joanne L Parker
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Nicolae Solcan
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Alette Brinth
- Schools of Medicine and Biochemistry & Immunology, Trinity College Dublin, Dublin, Ireland
| | - Dianfan Li
- Schools of Medicine and Biochemistry & Immunology, Trinity College Dublin, Dublin, Ireland
| | - Syed T A Shah
- Schools of Medicine and Biochemistry & Immunology, Trinity College Dublin, Dublin, Ireland
| | - Martin Caffrey
- Schools of Medicine and Biochemistry & Immunology, Trinity College Dublin, Dublin, Ireland
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford, UK
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26
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Newstead S. Molecular insights into proton coupled peptide transport in the PTR family of oligopeptide transporters. Biochim Biophys Acta Gen Subj 2014; 1850:488-99. [PMID: 24859687 PMCID: PMC4331665 DOI: 10.1016/j.bbagen.2014.05.011] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 12/15/2022]
Abstract
Background Cellular uptake of small peptides is an important physiological process mediated by the PTR family of proton-coupled peptide transporters. In bacteria peptides can be used as a source of amino acids and nitrogen. Similarly in humans peptide transport is the principle route for the uptake and retention of dietary protein in the form of short di- and tri-peptides for cellular metabolism. Scope of the review Recent crystal structures of bacterial PTR family transporters, combined with biochemical studies of transport have revealed key molecular details underpinning ligand promiscuity and the mechanism of proton-coupled transport within the family. Major conclusions Pairs of salt bridge interactions between transmembrane helices work in tandem to orchestrate alternating access transport within the PTR family. Key roles for residues conserved between bacterial and eukaryotic homologues suggest a conserved mechanism of peptide recognition and transport that in some cases has been subtly modified in individual species. General significance Physiological studies on PepT1 and PepT2, the mammalian members of this family, have identified these transporters as being responsible for the uptake of many pharmaceutically important drug molecules, including antibiotics and antiviral medications and demonstrated their promiscuity can be used for improving the oral bioavailability of poorly absorbed compounds. The insights gained from recent structural studies combined with previous physiological and biochemical analyses are rapidly advancing our understanding of this medically important transporter superfamily. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins. Crystal structures of PTR family transporters Identification of mechanistically important salt bridge interactions. Conservation of key functional residues between bacterial and mammalian homologues. High resolution structural information on peptide binding.
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Affiliation(s)
- Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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27
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Analysing the substrate multispecificity of a proton-coupled oligopeptide transporter using a dipeptide library. Nat Commun 2014; 4:2502. [PMID: 24060756 PMCID: PMC3791473 DOI: 10.1038/ncomms3502] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 08/23/2013] [Indexed: 01/26/2023] Open
Abstract
Peptide uptake systems that involve members of the proton-coupled oligopeptide transporter (POT) family are conserved across all organisms. POT proteins have characteristic substrate multispecificity, with which one transporter can recognize as many as 8,400 types of di/tripeptides and certain peptide-like drugs. Here we characterize the substrate multispecificity of Ptr2p, a major peptide transporter of Saccharomyces cerevisiae, using a dipeptide library. The affinities (Ki) of di/tripeptides toward Ptr2p show a wide distribution range from 48 mM to 0.020 mM. This substrate multispecificity indicates that POT family members have an important role in the preferential uptake of vital amino acids. In addition, we successfully establish high performance ligand affinity prediction models (97% accuracy) using our comprehensive dipeptide screening data in conjunction with simple property indices for describing ligand molecules. Our results provide an important clue to the development of highly absorbable peptides and their derivatives including peptide-like drugs. Proton-coupled oligopeptide transporters (POTs) can recognize and mediate the uptake of up to 8,400 di/tripeptides or peptide-like drugs. Ito et al. comprehensively map the substrate specificity of the yeast POT Ptr2p, and use this information to construct models for the prediction of ligand affinity.
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Sahoo S, Aurich MK, Jonsson JJ, Thiele I. Membrane transporters in a human genome-scale metabolic knowledgebase and their implications for disease. Front Physiol 2014; 5:91. [PMID: 24653705 PMCID: PMC3949408 DOI: 10.3389/fphys.2014.00091] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 02/17/2014] [Indexed: 01/18/2023] Open
Abstract
Membrane transporters enable efficient cellular metabolism, aid in nutrient sensing, and have been associated with various diseases, such as obesity and cancer. Genome-scale metabolic network reconstructions capture genomic, physiological, and biochemical knowledge of a target organism, along with a detailed representation of the cellular metabolite transport mechanisms. Since the first reconstruction of human metabolism, Recon 1, published in 2007, progress has been made in the field of metabolite transport. Recently, we published an updated reconstruction, Recon 2, which significantly improved the metabolic coverage and functionality. Human metabolic reconstructions have been used to investigate the role of metabolism in disease and to predict biomarkers and drug targets. Given the importance of cellular transport systems in understanding human metabolism in health and disease, we analyzed the coverage of transport systems for various metabolite classes in Recon 2. We will review the current knowledge on transporters (i.e., their preferred substrates, transport mechanisms, metabolic relevance, and disease association for each metabolite class). We will assess missing coverage and propose modifications and additions through a transport module that is functional when combined with Recon 2. This information will be valuable for further refinements. These data will also provide starting points for further experiments by highlighting areas of incomplete knowledge. This review represents the first comprehensive overview of the transporters involved in central metabolism and their transport mechanisms, thus serving as a compendium of metabolite transporters specific for human metabolic reconstructions.
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Affiliation(s)
- Swagatika Sahoo
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Maike K Aurich
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
| | - Jon J Jonsson
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Iceland Reykjavik, Iceland ; Department of Genetics and Molecular Medicine, Landspitali, National University Hospital of Iceland Reykjavik, Iceland
| | - Ines Thiele
- Center for Systems Biology, University of Iceland Reykjavik, Iceland ; Molecular Systems Physiology Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg Belval, Luxembourg
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Xu Q, Wang C, Meng Q, Liu Q, Sun P, Sun H, Guo X, Liu K. The oligopeptide transporter 2-mediated reabsorption of entecavir in rat kidney. Eur J Pharm Sci 2014; 52:41-7. [DOI: 10.1016/j.ejps.2013.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/16/2013] [Accepted: 10/16/2013] [Indexed: 11/17/2022]
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Nardon C, Schmitt SM, Yang H, Zuo J, Fregona D, Dou QP. Gold(III)-dithiocarbamato peptidomimetics in the forefront of the targeted anticancer therapy: preclinical studies against human breast neoplasia. PLoS One 2014; 9:e84248. [PMID: 24392119 PMCID: PMC3879379 DOI: 10.1371/journal.pone.0084248] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 11/13/2013] [Indexed: 11/19/2022] Open
Abstract
Since the serendipitous discovery of cisplatin, platinum-based drugs have become well-established antitumor agents, despite the fact that their clinical use is limited by many severe side-effects. In order to both improve the chemotherapeutic index and broaden the therapeutic spectrum of current drugs, our most recent anti-neoplastic agents, Au(III) complexes, were designed as carrier-mediated delivery systems exploiting peptide transporters, which are up-regulated in some cancers. Among all, we focused on two compounds and tested them on human MDA-MB-231 (resistant to cisplatin) breast cancer cell cultures and xenografts, discovering the proteasome as a major target both in vitro and in vivo. 53% inhibition of breast tumor growth in mice was observed after 27 days of treatment at 1.0 mg kg−1 d−1, compared to control. Remarkably, if only the most responsive mice are taken into account, 85% growth inhibition, with some animals showing tumor shrinkage, was observed after 13 days. These results led us to file an international patent, recognizing this class of gold(III) peptidomimetics as suitable candidates for entering phase I clinical trials.
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Affiliation(s)
- Chiara Nardon
- Department of Chemical Sciences, University of Padova, Padova, Italy
- Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Departments of Oncology, Pharmacology and Pathology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
| | - Sara M. Schmitt
- Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Departments of Oncology, Pharmacology and Pathology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
| | - Huanjie Yang
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Jian Zuo
- Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Departments of Oncology, Pharmacology and Pathology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, Shandong, China
| | - Dolores Fregona
- Department of Chemical Sciences, University of Padova, Padova, Italy
- * E-mail: (DF); (QPD)
| | - Q. Ping Dou
- Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Departments of Oncology, Pharmacology and Pathology, School of Medicine, Wayne State University, Detroit, Michigan, United States of America
- * E-mail: (DF); (QPD)
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Nadeem Q, Can D, Shen Y, Felber M, Mahmood Z, Alberto R. Synthesis of tripeptide derivatized cyclopentadienyl complexes of technetium and rhenium as radiopharmaceutical probes. Org Biomol Chem 2014; 12:1966-74. [DOI: 10.1039/c3ob41866a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: transporters. Br J Pharmacol 2013; 170:1706-96. [PMID: 24528242 PMCID: PMC3892292 DOI: 10.1111/bph.12450] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Transporters are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Peptide transporter DtpA has two alternate conformations, one of which is promoted by inhibitor binding. Proc Natl Acad Sci U S A 2013; 110:E3978-86. [PMID: 24082128 DOI: 10.1073/pnas.1312959110] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Peptide transporters (PTRs) of the large PTR family facilitate the uptake of di- and tripeptides to provide cells with amino acids for protein synthesis and for metabolic intermediates. Although several PTRs have been structurally and functionally characterized, how drugs modulate peptide transport remains unclear. To obtain insight into this mechanism, we characterize inhibitor binding to the Escherichia coli PTR dipeptide and tripeptide permease A (DtpA), which shows substrate specificities similar to its human homolog hPEPT1. After demonstrating that Lys[Z-NO2]-Val, the strongest inhibitor of hPEPT1, also acts as a high-affinity inhibitor for DtpA, we used single-molecule force spectroscopy to localize the structural segments stabilizing the peptide transporter and investigated which of these structural segments change stability upon inhibitor binding. This characterization was done with DtpA embedded in the lipid membrane and exposed to physiologically relevant conditions. In the unbound state, DtpA adopts two main alternate conformations in which transmembrane α-helix (TMH) 2 is either stabilized (in ∼43% of DtpA molecules) or not (in ∼57% of DtpA molecules). The two conformations are understood to represent the inward- and outward-facing conformational states of the transporter. With increasing inhibitor concentration, the conformation characterized by a stabilized TMH 2 becomes increasingly prevalent, reaching ∼92% at saturation. Our measurements further suggest that Lys[Z-NO2]-Val interacts with discrete residues in TMH 2 that are important for ligand binding and substrate affinity. These interactions in turn stabilize TMH 2, thereby promoting the inhibited conformation of DtpA.
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Wang Z, Pal D, Patel A, Kwatra D, Mitra AK. Influence of overexpression of efflux proteins on the function and gene expression of endogenous peptide transporters in MDR-transfected MDCKII cell lines. Int J Pharm 2012; 441:40-9. [PMID: 23262422 DOI: 10.1016/j.ijpharm.2012.12.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 11/26/2012] [Accepted: 12/12/2012] [Indexed: 11/28/2022]
Abstract
The objective of this study is to delineate whether overexpression of human efflux transporters (P-gp, MRP2, and BCRP) in transfected MDCK cells affect the functional activities, and gene and protein expression of endogenous influx peptide transporter system (PepT). Real-time PCR, immunoblotting, uptake and permeability studies of [(3)H]Gly-Sar were conducted on transfected MDCKII and wild-type cells to investigate functional differences. Cellular [(3)H]Gly-Sar accumulation was significantly lower in transfected MDCKII cell lines compared to wild-type cells. Transport efficiency of apical peptide transporters was markedly reduced to around 25%, 30%, and 40% in P-gp-, MRP2-, and BCRP-overexpressed MDCK cell lines, respectively. With ascending cell-passage, transport efficiency was enhanced. A significantly higher Gly-Sar permeability was observed across parental cell-monolayers over transfected cells at all pHs. Levels of mRNA for both canine PepT1 and PepT2 were substantially reduced when efflux transporters overexpressed but enhanced when mRNA-levels of efflux genes diminished with ascending cell-passage of transfected cells. An inverse correlation was evident between endogenous PepT and exogenous efflux transporters in transfected MDCKII cells. Results of protein expression also supported these findings. Overexpression of MDR genes can affect endogenous PepT function which might be due to the phenomenon of transporter-compensation resulting in down-regulation of endogenous genes.
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Affiliation(s)
- Zhiying Wang
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, Health Sciences Building, 2464 Charlotte Street, Kansas City, MO 64108-2718, USA
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35
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Kadam RS, Vooturi SK, Kompella UB. Immunohistochemical and functional characterization of peptide, organic cation, neutral and basic amino acid, and monocarboxylate drug transporters in human ocular tissues. Drug Metab Dispos 2012; 41:466-74. [PMID: 23169611 DOI: 10.1124/dmd.112.045674] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Since there is paucity of information on solute transporters in human ocular tissues, the aim of this study was immunohistochemical and functional characterization of peptide transporters (PEPT), organic cation transporters (OCTs), neutral and basic amino acid transporters (ATB(0,+)), and monocarboxylate transporters (MCTs) in human ocular barriers. Immunohistochemical localization of transporters was achieved using 5-µm-thick paraffin-embedded sections of whole human eyes. In vitro transport studies were carried out across human cornea and sclera-choroid-retinal pigment epithelium (SCRPE) using a cassette of specific substrates in the presence and absence of inhibitors to determine the role of transporters in transtissue solute delivery. Immunohistochemistry showed the expression of PEPT-1, PEPT-2, ATB(0,+), OCT-1, OCT-2, MCT-1, and MCT-3 in human ocular tissues. PEPT-1, PEPT-2, OCT-1, MCT-1, and ATB(0,+) expression was evident in the cornea, conjunctiva, ciliary epithelium, and neural retina. Expression of PEPT-1, PEPT-2, and OCT-1 was evident in choroid tissue as well. OCT-2 expression could be seen in the corneal and conjunctival epithelia, whereas MCT-3 expression was confined to the RPE layer. OCT-2 expression was evident in conjunctival blood vessel walls, whereas PEPT-1, PEPT-2, and OCT-1 were expressed in the choroid. Preliminary transport studies indicated inward transport of Gly-Sar (PEPT substrate), 1-methyl-4-phenylpyridinium (MPP+) (OCT substrate), and l-tryptophan (ATB(0,+) substrate) across cornea as well as SCRPE. For phenylacetic acid (MCT substrate), transporter-mediated inward transport across the cornea and outward transport across SCRPE were evident. Thus, PEPT, OCT, and ATB(0,+) are influx transporters present in human ocular barriers, and they can potentially be used for transporter-guided retinal drug delivery after topical, transscleral, and systemic administrations.
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Affiliation(s)
- Rajendra S Kadam
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Khomane KS, Nandekar PP, Wahlang B, Bagul P, Shaikh N, Pawar YB, Meena CL, Sangamwar AT, Jain R, Tikoo K, Bansal AK. Mechanistic Insights into PEPT1-Mediated Transport of a Novel Antiepileptic, NP-647. Mol Pharm 2012; 9:2458-68. [DOI: 10.1021/mp200672d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Kailas S. Khomane
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Prajwal P. Nandekar
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Banrida Wahlang
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Pravin Bagul
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Naeem Shaikh
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Yogesh B. Pawar
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Chhuttan Lal Meena
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Abhay T. Sangamwar
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Rahul Jain
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - K. Tikoo
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
| | - Arvind K. Bansal
- Department
of Pharmaceutics, ‡Department of Pharmacoinformatics, §Department of Medicinal Chemistry, and ∥Department of
Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector-67,
SAS Nagar, Mohali, Punjab, India
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Alternating access mechanism in the POT family of oligopeptide transporters. EMBO J 2012; 31:3411-21. [PMID: 22659829 PMCID: PMC3419923 DOI: 10.1038/emboj.2012.157] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 05/03/2012] [Indexed: 01/16/2023] Open
Abstract
Proton-dependent oligopeptide transporters are required for the uptake of diet-derived peptides in all kingdoms of life. The crystal structure of a bacterial transporter in the inward open conformation, together with a published structure in an occluded conformation, reveals the peptide transport mechanism. Short chain peptides are actively transported across membranes as an efficient route for dietary protein absorption and for maintaining cellular homeostasis. In mammals, peptide transport occurs via PepT1 and PepT2, which belong to the proton-dependent oligopeptide transporter, or POT family. The recent crystal structure of a bacterial POT transporter confirmed that they belong to the major facilitator superfamily of secondary active transporters. Despite the functional characterization of POT family members in bacteria, fungi and mammals, a detailed model for peptide recognition and transport remains unavailable. In this study, we report the 3.3-Å resolution crystal structure and functional characterization of a POT family transporter from the bacterium Streptococcus thermophilus. Crystallized in an inward open conformation the structure identifies a hinge-like movement within the C-terminal half of the transporter that facilitates opening of an intracellular gate controlling access to a central peptide-binding site. Our associated functional data support a model for peptide transport that highlights the importance of salt bridge interactions in orchestrating alternating access within the POT family.
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Stvolinsky S, Toropova K, Gordeeva M, Kazey V, Sato T, Meguro K, Boldyrev A. Carnosine and its (S)-Trolox™ derivative protect animals against oxidative stress. Amino Acids 2012; 43:165-70. [DOI: 10.1007/s00726-012-1256-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/17/2012] [Indexed: 10/28/2022]
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Ingersoll SA, Ayyadurai S, Charania MA, Laroui H, Yan Y, Merlin D. The role and pathophysiological relevance of membrane transporter PepT1 in intestinal inflammation and inflammatory bowel disease. Am J Physiol Gastrointest Liver Physiol 2012; 302:G484-92. [PMID: 22194420 PMCID: PMC3311434 DOI: 10.1152/ajpgi.00477.2011] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 12/21/2011] [Indexed: 01/31/2023]
Abstract
Intestinal inflammation is characterized by epithelial disruption, leading to loss of barrier function and the recruitment of immune cells, including neutrophils. Although the mechanisms are not yet completely understood, interactions between environmental and immunological factors are thought to be critical in the initiation and progression of intestinal inflammation. In recent years, it has become apparent that the di/tripeptide transporter PepT1 may play an important role in the pathogenesis of such inflammation. In healthy individuals, PepT1 is primarily expressed in the small intestine and transports di/tripeptides for metabolic purposes. However, during chronic inflammation such as that associated with inflammatory bowel disease, PepT1 expression is upregulated in the colon, wherein the protein is normally expressed either minimally or not at all. Several recent studies have shown that PepT1 binds to and transports various bacterial di/tripeptides into colon cells, leading to activation of downstream proinflammatory responses via peptide interactions with innate immune receptors. In the present review, we examine the relationship between colonic PepT1-mediated peptide transport in the colon and activation of innate immune responses during disease. It is important to understand the mechanisms of PepT1 action during chronic intestinal inflammation to develop future therapies addressing inappropriate immune activation in the colon.
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Affiliation(s)
- Sarah A Ingersoll
- Center for Diagnostics & Therapeutics, Department of Biology, Georgia State University, Atlanta, 30302-5090, USA.
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Kouodom MN, Ronconi L, Celegato M, Nardon C, Marchiò L, Dou QP, Aldinucci D, Formaggio F, Fregona D. Toward the selective delivery of chemotherapeutics into tumor cells by targeting peptide transporters: tailored gold-based anticancer peptidomimetics. J Med Chem 2012; 55:2212-26. [PMID: 22309237 DOI: 10.1021/jm201480u] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Complexes [Au(III)X(2)(dtc-Sar-AA-O(t-Bu))] (AA = Gly, X = Br (1)/Cl (2); AA = Aib, X = Br (3)/Cl (4); AA = l-Phe, X = Br (5)/Cl (6)) were designed on purpose in order to obtain gold(III)-based anticancer peptidomimetics that might specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy, and the crystal structure of [Au(III)Br(2)(dtc-Sar-Aib-O(t-Bu))] (3) was solved and refined. According to in vitro cytotoxicity studies, the Aib-containing complexes 3 and 4 turned out to be the most effective toward all the human tumor cell lines evaluated (PC3, DU145, 2008, C13, and L540), reporting IC(50) values much lower than that of cisplatin. Remarkably, they showed no cross-resistance with cisplatin itself and were proved to inhibit tumor cell proliferation by inducing either apoptosis or late apoptosis/necrosis depending on the cell lines. Biological results are here reported and discussed in terms of the structure-activity relationship.
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Affiliation(s)
- Morelle Negom Kouodom
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, Padova 35131, Italy
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Guo X, Meng Q, Liu Q, Wang C, Mao Q, Sun H, Peng J, Kaku T, Liu K. Peptide cotransporter 1 in intestine and organic anion transporters in kidney are targets of interaction between JBP485 and lisinopril in rats. Drug Metab Pharmacokinet 2011; 27:232-41. [PMID: 22123131 DOI: 10.2133/dmpk.dmpk-11-rg-089] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to clarify the pharmacokinetic mechanism of interaction between JBP485 (cyclo-trans-4-L-hydroxyprolyl-L-serine, a dipeptide with antihepatitis activity) and lisinopril (an angiotensin-converting enzyme inhibitor) in vitro and in vivo. When JBP485 and lisinopril were administered orally simultaneously, the plasma concentrations of the two drugs were decreased significantly, but few changes were observed after simultaneous intravenous administration of the two drugs. The uptake of JBP485 and lisinopril in everted intestinal sacs and in HeLa cells transfected with human peptide cotransporter 1 (PEPT1), as well as absorption of JBP485 and lisinopril after jejunal perfusion were reduced after simultaneous drug administration, which suggested that the first target of drug interaction was PEPT1 in the intestine during the absorption process. The cumulative urinary excretions and renal clearance of the two drugs were decreased after intravenous co-administration, while uptakes of the two drugs in kidney slices and hOAT1/hOAT3-transfected HEK293 cells were decreased. These results indicated that the second target of drug-drug interaction was located in the kidney. These findings confirmed that the pharmacokinetic mechanism of interaction between JBP485 and lisinopril could be explained by their inhibition of the same transporters in the intestinal mucosa (PEPT1) and kidneys (OATs).
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Affiliation(s)
- Xinjin Guo
- Department of Clinical Pharmacology, College of Pharmacy, Dalian Medical University, Dalian, China
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42
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Newstead S. Towards a structural understanding of drug and peptide transport within the proton-dependent oligopeptide transporter (POT) family. Biochem Soc Trans 2011; 39:1353-8. [PMID: 21936814 DOI: 10.1042/bst0391353] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
One of the principal aims of modern drug design is the targeted delivery of drugs within the body, such as to the central nervous system, combined with their exclusion from the liver and kidneys, which break down foreign molecules and subsequently eliminate them. Many of the commonly prescribed drugs are transported into cells and across the plasma membrane via endogenous membrane transporters, whose principal roles are the uptake of essential nutrients for metabolism. In many cases, such drug transport is serendipitous as they are simply mistaken as 'natural' compounds. Many of these transporters could, however, be targeted more efficiently, improving drug absorption, distribution and retention. The molecular details of these drug-transporter interactions, however, are at best poorly understood, in large part through the absence of any high-resolution structural information. To address this issue, we recently determined the structure of a prokaryotic peptide transporter, PepTSo from Shewanella oneidensis, which shares a high degree of sequence similarity and functional characteristics with the human PepT1 and PepT2 proteins. PepT1 and PepT2 contribute significantly to the oral bioavailability and pharmacokinetic properties of a number of important drug families, including antibiotics, antivirals and anticancer agents. The crystal structure of PepTSo provides the first high-resolution model of a drug importer and provides the starting point for understanding drug and peptide transport within the human body.
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Affiliation(s)
- Simon Newstead
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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Pedretti A, De Luca L, Marconi C, Regazzoni L, Aldini G, Vistoli G. Fragmental modeling of hPepT2 and analysis of its binding features by docking studies and pharmacophore mapping. Bioorg Med Chem 2011; 19:4544-51. [DOI: 10.1016/j.bmc.2011.06.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 06/01/2011] [Accepted: 06/08/2011] [Indexed: 11/29/2022]
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Kramer W. Transporters, Trojan horses and therapeutics: suitability of bile acid and peptide transporters for drug delivery. Biol Chem 2011; 392:77-94. [PMID: 21194371 DOI: 10.1515/bc.2011.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Membrane transporters are major determinants for the pharmacokinetic, safety and efficacy behavior of drugs. Available technologies to study function and structure of transport proteins has strongly stimulated research in transporter biology and uncovered their importance for the drug discovery and development process, especially for drug absorption and disposition. Physiological transport systems are investigated as potential ferries to improve drug absorption and membrane permeation and to achieve organ-specific drug action. In particular, the bile acid transport systems in the liver and the small intestine and the oligopeptide transporters are of significant importance for molecular drug delivery.
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Affiliation(s)
- Werner Kramer
- Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, Gebäude G 879, Frankfurt/Main, Germany.
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Newstead S, Drew D, Cameron AD, Postis VLG, Xia X, Fowler PW, Ingram JC, Carpenter EP, Sansom MSP, McPherson MJ, Baldwin SA, Iwata S. Crystal structure of a prokaryotic homologue of the mammalian oligopeptide-proton symporters, PepT1 and PepT2. EMBO J 2011; 30:417-26. [PMID: 21131908 PMCID: PMC3025455 DOI: 10.1038/emboj.2010.309] [Citation(s) in RCA: 209] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 11/04/2010] [Indexed: 01/24/2023] Open
Abstract
PepT1 and PepT2 are major facilitator superfamily (MFS) transporters that utilize a proton gradient to drive the uptake of di- and tri-peptides in the small intestine and kidney, respectively. They are the major routes by which we absorb dietary nitrogen and many orally administered drugs. Here, we present the crystal structure of PepT(So), a functionally similar prokaryotic homologue of the mammalian peptide transporters from Shewanella oneidensis. This structure, refined using data up to 3.6 Å resolution, reveals a ligand-bound occluded state for the MFS and provides new insights into a general transport mechanism. We have located the peptide-binding site in a central hydrophilic cavity, which occludes a bound ligand from both sides of the membrane. Residues thought to be involved in proton coupling have also been identified near the extracellular gate of the cavity. Based on these findings and associated kinetic data, we propose that PepT(So) represents a sound model system for understanding mammalian peptide transport as catalysed by PepT1 and PepT2.
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Affiliation(s)
- Simon Newstead
- Division of Molecular Biosciences, Membrane Protein Crystallography Group, Imperial College London, London, UK.
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Hammes UZ, Meier S, Dietrich D, Ward JM, Rentsch D. Functional properties of the Arabidopsis peptide transporters AtPTR1 and AtPTR5. J Biol Chem 2010; 285:39710-7. [PMID: 20937801 DOI: 10.1074/jbc.m110.141457] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Arabidopsis di- and tripeptide transporters AtPTR1 and AtPTR5 were expressed in Xenopus laevis oocytes, and their selectivity and kinetic properties were determined by voltage clamping and by radioactive uptake. Dipeptide transport by AtPTR1 and AtPTR5 was found to be electrogenic and dependent on protons but not sodium. In the absence of dipeptides, both transporters showed proton-dependent leak currents that were inhibited by Phe-Ala (AtPTR5) and Phe-Ala, Trp-Ala, and Phe-Phe (AtPTR1). Phe-Ala was shown to reduce leak currents by binding to the substrate-binding site with a high apparent affinity. Inhibition of leak currents was only observed when the aromatic amino acids were present at the N-terminal position. AtPTR1 and AtPTR5 transport activity was voltage-dependent, and currents increased supralinearly with more negative membrane potentials and did not saturate. The voltage dependence of the apparent affinities differed between Ala-Ala, Ala-Lys, and Ala-Asp and was not conserved between the two transporters. The apparent affinity of AtPTR1 for these dipeptides was pH-dependent and decreased with decreasing proton concentration. In contrast to most proton-coupled transporters characterized so far, -I(max) increased at high pH, indicating that regulation of the transporter by pH overrides the importance of protons as co-substrate.
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Affiliation(s)
- Ulrich Z Hammes
- Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland
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Dipeptides in nutrition and therapy: cyanophycin-derived dipeptides as natural alternatives and their biotechnological production. Appl Microbiol Biotechnol 2010; 87:815-28. [DOI: 10.1007/s00253-010-2641-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 04/18/2010] [Accepted: 04/20/2010] [Indexed: 10/19/2022]
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Omkvist DH, Larsen SB, Nielsen CU, Steffansen B, Olsen L, Jørgensen FS, Brodin B. A quantitative structure-activity relationship for translocation of tripeptides via the human proton-coupled peptide transporter, hPEPT1 (SLC15A1). AAPS JOURNAL 2010; 12:385-96. [PMID: 20449699 DOI: 10.1208/s12248-010-9195-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 04/09/2010] [Indexed: 11/30/2022]
Abstract
The human intestinal proton-coupled peptide transporter, hPEPT1 (SLC15A1), has been identified as an absorptive transporter for both drug substances and prodrugs. An understanding of the prerequisites for transport has so far been obtained from models based on competition experiments. These models have limited value for predicting substrate translocation via hPEPT1. The aim of the present study was to investigate the requirements for translocation via hPEPT1. A set of 55 tripeptides was selected from a principal component analysis based on VolSurf descriptors using a statistical design. The majority of theses tripeptides have not previously been investigated. Translocation of the tripeptides via hPEPT1 was determined in a MDCK/hPEPT1 cell-based translocation assay measuring substrate-induced changes in fluorescence of a membrane potential-sensitive probe. Affinities for hPEPT1 of relevant tripeptides were determined by competition studies with [14C]Gly-Sar in MDCK/hPEPT1 cells. Forty tripeptides were found to be substrates for hPEPT1, having K(m)(app) values in the range 0.4-28 mM. Eight tripeptides were not able to cause a substrate-induced change in fluorescence in the translocation assay and seven tripeptides interacted with the probe itself. The conformationally restricted tripeptide Met-Pro-Pro was identified as a novel high-affinity inhibitor of hPEPT1. We also discovered the first tripeptide (Asp-Ile-Arg) that was neither a substrate nor an inhibitor of hPEPT1. To rationalise the requirements for transport, a quantitative structure-activity relationship model correlating K(m)(app) values with VolSurf descriptors was constructed. This is, to our knowledge, the first predictive model for the translocation of tripeptides via hPEPT1.
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Affiliation(s)
- Diana Højmark Omkvist
- Drug Transporters in ADME, Department of Pharmaceutics and Analytical Chemistry, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
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Brandsch M, Knütter I, Bosse-Doenecke E. Pharmaceutical and pharmacological importance of peptide transporters. J Pharm Pharmacol 2010; 60:543-85. [DOI: 10.1211/jpp.60.5.0002] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AbstractPeptide transport is currently a prominent topic in membrane research. The transport proteins involved are under intense investigation because of their physiological importance in protein absorption and also because peptide transporters are possible vehicles for drug delivery. Moreover, in many tissues peptide carriers transduce peptidic signals across membranes that are relevant in information processing. The focus of this review is on the pharmaceutical relevance of the human peptide transporters PEPT1 and PEPT2. In addition to their physiological substrates, both carriers transport many β-lactam antibiotics, valaciclovir and other drugs and prodrugs because of their sterical resemblance to di- and tripeptides. The primary structure, tissue distribution and substrate specificity of PEPT1 and PEPT2 have been well characterized. However, there is a dearth of knowledge on the substrate binding sites and the three-dimensional structure of these proteins. Until this pivotal information becomes available by X-ray crystallography, the development of new drug substrates relies on classical transport studies combined with molecular modelling. In more than thirty years of research, data on the interaction of well over 700 di- and tripeptides, amino acid and peptide derivatives, drugs and prodrugs with peptide transporters have been gathered. The aim of this review is to put the reports on peptide transporter-mediated drug uptake into perspective. We also review the current knowledge on pharmacogenomics and clinical relevance of human peptide transporters. Finally, the reader's attention is drawn to other known or proposed human peptide-transporting proteins.
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Affiliation(s)
- Matthias Brandsch
- Membrane Transport Group, Biozentrum of the Martin-Luther-University Halle-Wittenberg, D-06120 Halle, Germany
| | - Ilka Knütter
- Membrane Transport Group, Biozentrum of the Martin-Luther-University Halle-Wittenberg, D-06120 Halle, Germany
| | - Eva Bosse-Doenecke
- Institute of Biochemistry/Biotechnology, Faculty of Science I, Martin-Luther-University Halle-Wittenberg, D-06120 Halle, Germany
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Shigeoka AA, Kambo A, Mathison JC, King AJ, Hall WF, da Silva Correia J, Ulevitch RJ, McKay DB. Nod1 and nod2 are expressed in human and murine renal tubular epithelial cells and participate in renal ischemia reperfusion injury. THE JOURNAL OF IMMUNOLOGY 2010; 184:2297-304. [PMID: 20124104 DOI: 10.4049/jimmunol.0903065] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nucleotide-binding oligomerization domain (Nod) 1 and Nod2 are members of a family of intracellular innate sensors that participate in innate immune responses to pathogens and molecules released during the course of tissue injury, including injury induced by ischemia. Ischemic injury to the kidney is characterized by renal tubular epithelial apoptosis and inflammation. Among the best studied intracellular innate immune receptors known to contribute to apoptosis and inflammation are Nod1 and Nod2. Our study compared and contrasted the effects of renal ischemia in wild-type mice and mice deficient in Nod1, Nod2, Nod(1 x 2), and in their downstream signaling molecule receptor-interacting protein 2. We found that Nod1 and Nod2 were present in renal tubular epithelial cells in both mouse and human kidneys and that the absence of these receptors in mice resulted in protection from kidney ischemia reperfusion injury. Significant protection from kidney injury was seen with a deficiency of Nod2 and receptor-interacting protein 2, and the simultaneous deficiency of Nod1 and Nod2 provided even greater protection. We conclude that the intracellular sensors Nod1 and Nod2 play an important role in the pathogenesis of acute ischemic injury of the kidney, although possibly through different mechanisms.
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Affiliation(s)
- Alana A Shigeoka
- Department of Immunology and Microbial Sciences, The Scripps Research Institute, La Jolla, CA 92037, USA
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