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Wittern CI, Schröder S, Jensen O, Brockmöller J, Gebauer L. Comprehensive characterization of the OCT1 phenylalanine-244-alanine substitution reveals highly substrate-dependent effects on transporter function. J Biol Chem 2024; 300:107835. [PMID: 39342994 DOI: 10.1016/j.jbc.2024.107835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 09/09/2024] [Accepted: 09/18/2024] [Indexed: 10/01/2024] Open
Abstract
Organic cation transporters (OCTs) can transport structurally highly diverse substrates. The molecular basis of this extensive polyspecificity has been further elucidated by cryo-EM. Apparently, in addition to negatively charged amino acids, aromatic residues may contribute to substrate binding and substrate selectivity. In this study, we provide a comprehensive characterization of phenylalanine 244 in OCT1 function. We analyzed the uptake of 144 OCT1 substrates for the phenylalanine 244 to alanine substitution compared to WTOCT1. This substitution had highly substrate-specific effects ranging from transport reduced to 10% of WT activity up to 8-fold increased transport rates. Four percent of substrates showed strongly increased uptake (>200% of WT) whereas 39% showed strongly reduced transport (<50% of WT). Particularly with larger, more hydrophobic, and more aromatic substrates, the Phe244Ala substitution resulted in higher transport rates and lower inhibition of the transporter. In contrast, substrates with a lower molecular weight and less aromatic rings showed generally decreased uptake rates. A comparison of our data to available transport kinetic data demonstrates that generally, high-affinity low-capacity substrates show increased uptake by the Phe244Ala substitution, whereas low-affinity high-capacity substrates are characterized by reduced transport rates. Altogether, our study provides the first comprehensive characterization of the functional role of an aromatic amino acid within the substrate translocation pathway of OCT1. The pleiotropic function further highlights that phenylalanine 244 interacts in a highly specific manner with OCT1 substrates and inhibitors.
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Affiliation(s)
- Carla Isabel Wittern
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Sophie Schröder
- Department for Epigenetics and Systems Medicine in Neurodegenerative Diseases, German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany
| | - Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen, Germany.
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2
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Malani M, Hiremath MS, Sharma S, Jhunjhunwala M, Gayen S, Hota C, Nirmal J. Interaction of systemic drugs causing ocular toxicity with organic cation transporter: an artificial intelligence prediction. J Biomol Struct Dyn 2024; 42:5207-5218. [PMID: 37340665 DOI: 10.1080/07391102.2023.2226717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 06/09/2023] [Indexed: 06/22/2023]
Abstract
Chronic disease patients (cancer, arthritis, cardiovascular diseases) undergo long-term systemic drug treatment. Membrane transporters in ocular barriers could falsely recognize these drugs and allow their trafficking into the eye from systemic circulation. Hence, despite their pharmacological activity, these drugs accumulate and cause toxicity at the non-target site, such as the eye. Since around 40% of clinically used drugs are organic cation in nature, it is essential to understand the role of organic cation transporter (OCT1) in ocular barriers to facilitate the entry of systemic drugs into the eye. We applied machine learning techniques and computer simulation models (molecular dynamics and metadynamics) in the current study to predict the potential OCT1 substrates. Artificial intelligence models were developed using a training dataset of a known substrates and non-substrates of OCT1 and predicted the potential OCT1 substrates from various systemic drugs causing ocular toxicity. Computer simulation studies was performed by developing the OCT1 homology model. Molecular dynamic simulations equilibrated the docked protein-ligand complex. And metadynamics revealed the movement of substrates across the transporter with minimum free energy near the binding pocket. The machine learning model showed an accuracy of about 80% and predicted the potential substrates for OCT1 among systemic drugs causing ocular toxicity - not known earlier, such as cyclophosphamide, bupivacaine, bortezomib, sulphanilamide, tosufloxacin, topiramate, and many more. However, further invitro and invivo studies are required to confirm these predictions.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Manisha Malani
- Translational Pharmaceutics Research Laboratory, Birla Institute of Technology and Science-Pilani, Hyderabad, Telangana, India
| | - Manthan S Hiremath
- Translational Pharmaceutics Research Laboratory, Birla Institute of Technology and Science-Pilani, Hyderabad, Telangana, India
| | - Surbhi Sharma
- Department of Computer Science and Information Systems (CSIS), Birla Institute of Technology & Science-Pilani, Hyderabad, Telangana, India
| | - Manisha Jhunjhunwala
- Department of Computer Science and Information Systems (CSIS), Birla Institute of Technology & Science-Pilani, Hyderabad, Telangana, India
| | - Shovanlal Gayen
- Laboratory of Drug Design and Discovery, Department of Pharmaceutical Technology, Jadavpur University, Kolkata, West Bengal, India
| | - Chittaranjan Hota
- Department of Computer Science and Information Systems (CSIS), Birla Institute of Technology & Science-Pilani, Hyderabad, Telangana, India
| | - Jayabalan Nirmal
- Translational Pharmaceutics Research Laboratory, Birla Institute of Technology and Science-Pilani, Hyderabad, Telangana, India
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Wang Y, Jia X, Cong B. Advances in the mechanism of metformin with wide-ranging effects on regulation of the intestinal microbiota. Front Microbiol 2024; 15:1396031. [PMID: 38855769 PMCID: PMC11157079 DOI: 10.3389/fmicb.2024.1396031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 04/29/2024] [Indexed: 06/11/2024] Open
Abstract
Metformin is of great focus because of its high safety, low side effects, and various effects other than lowering blood sugar, such as anti-inflammation, anti-tumor, and anti-aging. Studies have shown that metformin has a modulating effect on the composition and function of the intestinal microbiota other than acting on the liver. However, the composition of microbiota is complex and varies to some extent between species and individuals, and the experimental design of each study is also different. Multiple factors present a major obstacle to better comprehending the effects of metformin on the gut microbiota. This paper reviews the regulatory effects of metformin on the gut microbiota, such as increasing the abundance of genus Akkermansia, enriching short-chain fatty acids (SCFAs)-producing bacterial genus, and regulating gene expression of certain genera. The intestinal microbiota is a large and vital ecosystem in the human body and is considered to be the equivalent of an "organ" of the human body, which is highly relevant to human health and disease status. There are a lot of evidences that the gut microbiota is responsible for metformin's widespread effects. However, there are only a few systematic studies on this mechanism, and the specific mechanism is still unclear. This paper aims to summarize the possible mechanism of metformin in relation to gut microbiota.
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Affiliation(s)
- Yue Wang
- College of Forensic Medicine, Hebei Key Laboratory of Forensic Medicine, Hebei Medical University, Shijiazhuang, China
- Research Unit of Digestive Tract Microecosystem Pharmacology and Toxicology, Chinese Academy of Medical Sciences, Beijing, China
| | - Xianxian Jia
- College of Forensic Medicine, Hebei Key Laboratory of Forensic Medicine, Hebei Medical University, Shijiazhuang, China
- Research Unit of Digestive Tract Microecosystem Pharmacology and Toxicology, Chinese Academy of Medical Sciences, Beijing, China
- Department of Pathogen Biology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Bin Cong
- College of Forensic Medicine, Hebei Key Laboratory of Forensic Medicine, Hebei Medical University, Shijiazhuang, China
- Research Unit of Digestive Tract Microecosystem Pharmacology and Toxicology, Chinese Academy of Medical Sciences, Beijing, China
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Redeker KEM, Schröder S, Dücker C, Brockmöller J, Gebauer L. Targeted mutagenesis of negatively charged amino acids outlining the substrate translocation path within the human organic cation transporter 3. Biochem Pharmacol 2024; 223:116188. [PMID: 38580166 DOI: 10.1016/j.bcp.2024.116188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/12/2024] [Accepted: 04/02/2024] [Indexed: 04/07/2024]
Abstract
Recently published cryo-EM structures of human organic cation transporters of the SLC22 family revealed seven, sequentially arranged glutamic and aspartic acid residues, which may be relevant for interactions with positively charged substrates. We analyzed the functional consequences of removing those negative charges by creating D155N, E232Q, D382N, E390Q, E451Q, E459Q, and D478N mutants of OCT3. E232Q, E459Q, and D478N resulted in a lack of localization in the outer cell membrane and no relevant uptake activity. However, D155N and E451Q showed a substrate-specific loss of transport activity, whereas E390Q had no remaining activity despite correct membrane localization. In contrast, D382N showed almost wild-type-like uptake. D155 is located at the entrance to the substrate binding pocket and could, therefore be involved in guiding cationic substrates towards the inside of the binding pocket. For E390, we confirm its critical function for transporter function as it was recently shown for the corresponding position in OCT1. Interestingly, E451 seems to be located at the bottom of the binding pocket in the outward-open confirmation of the transporter. Substrate-specific loss of transport activity of the E451Q variant suggests an essential role in the transport cycle of specific substances as part of an opportunistic binding site. In general, our study highlights the impact of the cryo-EM structures in guiding mutagenesis studies to understand the molecular level of transporter-ligand interactions, and it also confirms the importance of testing multiple substrates in mutagenesis studies of polyspecific OCTs.
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Affiliation(s)
- Kyra-Elisa M Redeker
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany.
| | - Sophie Schröder
- Department for Epigenetics and Systems Medicine in Neurodegenerative Diseases, German Center for Neurodegenerative Diseases (DZNE), D-37075 Göttingen, Germany
| | - Christof Dücker
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany
| | - Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, D-37075 Göttingen, Germany
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Meyer-Tönnies MJ, Tzvetkov MV. The end of the beginning in understanding SLC22 polyspecificity. Trends Pharmacol Sci 2023; 44:397-399. [PMID: 37117104 DOI: 10.1016/j.tips.2023.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 04/30/2023]
Abstract
SLC22 transporters involved in drug elimination and organ distribution are polyspecific. Now, the first cryo-EM structure of SLC22A3 (OCT3) is available from the Sitte and Korkhov groups. It paves the way for better understanding OCT3 function and for revealing the exact mechanisms conferring polyspecificity of the whole SLC22 family.
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Affiliation(s)
- Marleen Julia Meyer-Tönnies
- Department of General Pharmacology, Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany
| | - Mladen Vassilev Tzvetkov
- Department of General Pharmacology, Institute of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany.
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Damanhouri ZA, Alkreathy HM, Alharbi FA, Abualhamail H, Ahmad MS. A Review of the Impact of Pharmacogenetics and Metabolomics on the Efficacy of Metformin in Type 2 Diabetes. Int J Med Sci 2023; 20:142-150. [PMID: 36619226 PMCID: PMC9812811 DOI: 10.7150/ijms.77206] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 12/02/2022] [Indexed: 01/06/2023] Open
Abstract
Metformin is the most often prescribed drug for people with type 2 diabetes (T2D). More than 120 million patients with T2D use metformin worldwide. However, monotherapy fails to achieve glycemic control in a third of the treated patients. Genetics contribute to some of the inter-individual variations in glycemic response to metformin. Numerous pharmacogenetic studies have demonstrated that variations in genes related to pharmacokinetics and pharmacodynamics of metformin's encoding transporters are mainly associated with metformin response. The goal of this review is to evaluate the current state of metformin pharmacogenetics and metabolomics research, discuss the clinical and scientific issues that need to be resolved in order to increase our knowledge of patient response variability to metformin, and how to improve patient outcomes. Metformin's hydrophilic nature and absorption as well as its action mechanism and effectiveness on T2D initiation are discussed. The impacts of variations associated with various genes are analysed to identify and evaluate the effect of genetic polymorphisms on the therapeutic activity of metformin. The metabolic pattern of T2D and metformin is also indicated. This is to emphasise that studies of pharmacogenetics and metabolomics could expand our knowledge of metformin response in T2D.
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Affiliation(s)
- Zoheir A Damanhouri
- Pharmacology Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Huda M Alkreathy
- Pharmacology Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Fawaz A Alharbi
- Pharmacology Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Haneen Abualhamail
- Pharmacology Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Muhammad S Ahmad
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
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Nies AT, Schaeffeler E, Schwab M. Hepatic solute carrier transporters and drug therapy: Regulation of expression and impact of genetic variation. Pharmacol Ther 2022; 238:108268. [DOI: 10.1016/j.pharmthera.2022.108268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/25/2022] [Accepted: 08/15/2022] [Indexed: 11/30/2022]
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Cloning and Functional Characterization of Dog OCT1 and OCT2: Another Step in Exploring Species Differences in Organic Cation Transporters. Int J Mol Sci 2022; 23:ijms23095100. [PMID: 35563491 PMCID: PMC9102066 DOI: 10.3390/ijms23095100] [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: 03/28/2022] [Revised: 04/28/2022] [Accepted: 04/30/2022] [Indexed: 12/21/2022] Open
Abstract
OCT1 and OCT2 are polyspecific membrane transporters that are involved in hepatic and renal drug clearance in humans and mice. In this study, we cloned dog OCT1 and OCT2 and compared their function to the human and mouse orthologs. We used liver and kidney RNA to clone dog OCT1 and OCT2. The cloned and the publicly available RNA-Seq sequences differed from the annotated exon-intron structure of OCT1 in the dog genome CanFam3.1. An additional exon between exons 2 and 3 was identified and confirmed by sequencing in six additional dog breeds. Next, dog OCT1 and OCT2 were stably overexpressed in HEK293 cells and the transport kinetics of five drugs were analyzed. We observed strong differences in the transport kinetics between dog and human orthologs. Dog OCT1 transported fenoterol with 12.9-fold higher capacity but 14.3-fold lower affinity (higher KM) than human OCT1. Human OCT1 transported ipratropium with 5.2-fold higher capacity but 8.4-fold lower affinity than dog OCT1. Compared to human OCT2, dog OCT2 showed 10-fold lower transport of fenoterol and butylscopolamine. In conclusion, the functional characterization of dog OCT1 and OCT2 reported here may have implications when using dogs as pre-clinical models as well as for drug therapy in dogs.
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