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Mazza T, Scalise M, Console L, Galluccio M, Giangregorio N, Tonazzi A, Pochini L, Indiveri C. Carnitine traffic and human fertility. Biochem Pharmacol 2024; 230:116565. [PMID: 39368751 DOI: 10.1016/j.bcp.2024.116565] [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: 07/31/2024] [Revised: 09/18/2024] [Accepted: 10/01/2024] [Indexed: 10/07/2024]
Abstract
Carnitine is a vital molecule in human metabolism, prominently involved in fatty acid β-oxidation within mitochondria. Predominantly sourced from dietary intake, carnitine also derives from endogenous synthesis. This review delves into the complex network of carnitine transport and distribution, emphasizing its pivotal role in human fertility. Together with its role in fatty acid oxidation, carnitine modulates the acety-CoA/CoA ratio, influencing carbohydrate metabolism, lipid biosynthesis, and gene expression. The intricate regulation of carnitine homeostasis involves a network of membrane transporters, notably OCTN2, which is central in its absorption, reabsorption, and distribution. OCTN2 dysfunction, results in Primary Carnitine Deficiency (PCD), characterized by systemic carnitine depletion and severe clinical manifestations, including fertility issues. In the male reproductive system, carnitine is crucial for sperm maturation and motility. In the female reproductive system, carnitine supports mitochondrial function necessary for oocyte quality, folliculogenesis, and embryonic development. Indeed, deficiencies in carnitine or its transporters have been linked to asthenozoospermia, reduced sperm quality, and suboptimal fertility outcomes in couples. Moreover, the antioxidant properties of carnitine protect spermatozoa from oxidative stress and help in managing conditions like polycystic ovary syndrome (PCOS) and endometriosis, enhancing sperm viability and fertilization potential of oocytes. This review summarizes the key role of membrane transporters in guaranteeing carnitine homeostasis with a special focus on the implications in fertility and possible treatments of infertility and other related disorders.
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Affiliation(s)
- Tiziano Mazza
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, Arcavacata di Rende 87036, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, Arcavacata di Rende 87036, Italy
| | - Lara Console
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, Arcavacata di Rende 87036, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, Arcavacata di Rende 87036, Italy
| | - Nicola Giangregorio
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), via Amendola 122/O, Bari 70126, Italy
| | - Annamaria Tonazzi
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), via Amendola 122/O, Bari 70126, Italy
| | - Lorena Pochini
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, Arcavacata di Rende 87036, Italy; CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), via Amendola 122/O, Bari 70126, Italy.
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Via P. Bucci 4C, Arcavacata di Rende 87036, Italy; CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnology (IBIOM), via Amendola 122/O, Bari 70126, Italy.
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Pike B, Zhao J, Hicks JA, Wang F, Hagen R, Liu HC, Odle J, Lin X. Intestinal Carnitine Status and Fatty Acid Oxidation in Response to Clofibrate and Medium-Chain Triglyceride Supplementation in Newborn Pigs. Int J Mol Sci 2023; 24:ijms24076066. [PMID: 37047049 PMCID: PMC10094207 DOI: 10.3390/ijms24076066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/13/2023] [Accepted: 03/15/2023] [Indexed: 04/14/2023] Open
Abstract
To investigate the role of peroxisome proliferator-activated receptor alpha (PPARα) in carnitine status and intestinal fatty acid oxidation in neonates, a total of 72 suckled newborn piglets were assigned into 8 dietary treatments following a 2 (±0.35% clofibrate) × 4 (diets with: succinate+glycerol (Succ), tri-valerate (TC5), tri-hexanoate (TC6), or tri-2-methylpentanoate (TMPA)) factorial design. All pigs received experimental milk diets with isocaloric energy for 5 days. Carnitine statuses were evaluated, and fatty acid oxidation was measured in vitro using [1-14C]-palmitic acid (1 mM) as a substrate in absence or presence of L659699 (1.6 µM), iodoacetamide (50 µM), and carnitine (1 mM). Clofibrate increased concentrations of free (41%) and/or acyl-carnitine (44% and 15%) in liver and plasma but had no effects in the intestine. The effects on carnitine status were associated with the expression of genes involved in carnitine biosynthesis, absorption, and transportation. TC5 and TMPA stimulated the increased fatty acid oxidation rate induced by clofibrate, while TC6 had no effect on the increased fatty acid oxidation induced by clofibrate (p > 0.05). These results suggest that dietary clofibrate improved carnitine status and increased fatty acid oxidation. Propionyl-CoA, generated from TC5 and TMPA, could stimulate the increased fatty acid oxidation rate induced by clofibrate as anaplerotic carbon sources.
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Affiliation(s)
- Brandon Pike
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Jinan Zhao
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Julie A Hicks
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Feng Wang
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Rachel Hagen
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Hsiao-Ching Liu
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Jack Odle
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Xi Lin
- Laboratory of Developmental Nutrition, Department of Animal Sciences, North Carolina State University, Raleigh, NC 27695, USA
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Gyimesi G, Hediger MA. Transporter-Mediated Drug Delivery. Molecules 2023; 28:molecules28031151. [PMID: 36770817 PMCID: PMC9919865 DOI: 10.3390/molecules28031151] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/12/2023] [Accepted: 01/18/2023] [Indexed: 01/27/2023] Open
Abstract
Transmembrane transport of small organic and inorganic molecules is one of the cornerstones of cellular metabolism. Among transmembrane transporters, solute carrier (SLC) proteins form the largest, albeit very diverse, superfamily with over 400 members. It was recognized early on that xenobiotics can directly interact with SLCs and that this interaction can fundamentally determine their efficacy, including bioavailability and intertissue distribution. Apart from the well-established prodrug strategy, the chemical ligation of transporter substrates to nanoparticles of various chemical compositions has recently been used as a means to enhance their targeting and absorption. In this review, we summarize efforts in drug design exploiting interactions with specific SLC transporters to optimize their therapeutic effects. Furthermore, we describe current and future challenges as well as new directions for the advanced development of therapeutics that target SLC transporters.
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The Role of Organic Cation Transporters in the Pharmacokinetics, Pharmacodynamics and Drug-Drug Interactions of Tyrosine Kinase Inhibitors. Int J Mol Sci 2023; 24:ijms24032101. [PMID: 36768423 PMCID: PMC9917293 DOI: 10.3390/ijms24032101] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Tyrosine kinase inhibitors (TKIs) decisively contributed in revolutionizing the therapeutic approach to cancer, offering non-invasive, tolerable therapies for a better quality of life. Nonetheless, degree and duration of the response to TKI therapy vary depending on cancer molecular features, the ability of developing resistance to the drug, on pharmacokinetic alterations caused by germline variants and unwanted drug-drug interactions at the level of membrane transporters and metabolizing enzymes. A great deal of approved TKIs are inhibitors of the organic cation transporters (OCTs). A handful are also substrates of them. These transporters are polyspecific and highly expressed in normal epithelia, particularly the intestine, liver and kidney, and are, hence, arguably relevant sites of TKI interactions with other OCT substrates. Moreover, OCTs are often repressed in cancer cells and might contribute to the resistance of cancer cells to TKIs. This article reviews the OCT interactions with approved and in-development TKIs reported in vitro and in vivo and critically discusses the potential clinical ramifications thereof.
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Thanh LP, Jiang Q, Wichasit N, Batistel F, Parys C, Guyader J, Loor JJ. Alterations in Skeletal Muscle mRNA Abundance in Response to Ethyl-Cellulose Rumen-Protected Methionine during the Periparturient Period in Dairy Cows. Animals (Basel) 2022; 12:ani12131641. [PMID: 35804540 PMCID: PMC9264958 DOI: 10.3390/ani12131641] [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: 05/09/2022] [Revised: 06/17/2022] [Accepted: 06/23/2022] [Indexed: 11/16/2022] Open
Abstract
This study aimed to evaluate the effect of feeding ethyl cellulose rumen-protected methionine (RPM) on skeletal muscle mRNA abundance during the periparturient period. Sixty multiparous Holstein cows were used in a block design and assigned to either a control or RPM diet. The RPM was supplied from −28 to 60 days in milk (DIM) at a rate of 0.09% (prepartum) or 0.10% (postpartum) of dry matter (DM), ensuring a Lys:Met in the metabolizable protein of ~2.8:1. Muscle biopsies were collected at −21, 1, and 21 DIM. Thirty-five target genes associated with nutrient metabolism and biochemical pathways were measured via RT-qPCR. The mRNA abundance of genes associated with amino acid (AA) transport (SLC7A8, SLC43A2), carnitine transport (SLC22A5), insulin signaling (IRS1), and antioxidant response (NFE2L2) had diet × time effect (p < 0.05) due to greater abundance in RPM versus CON cows, especially at 1 and 21 DIM. Members of the AA transport (SLC7A8, SLC25A29, SCL38A9), fatty acid β-oxidation (ACADVL), vitamin transport (SLC5A6, SLC19A2), mTOR pathway (AKT1 and mTOR), antioxidant response (KEAP1, CUL3), CDP-Choline pathway and arginine metabolism had overall greater abundance (p < 0.05) in RPM versus CON cows. Overall, data indicate that RPM can alter nutrient metabolism in the skeletal muscle around parturition partly through alterations in mRNA abundance.
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Affiliation(s)
- Lam Phuoc Thanh
- Department of Animal Sciences, Can Tho University, Ninh Kieu, Can Tho 94000, Vietnam;
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801, USA; (Q.J.); (N.W.)
| | - Qianming Jiang
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801, USA; (Q.J.); (N.W.)
| | - Nithat Wichasit
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801, USA; (Q.J.); (N.W.)
- Department of Agricultural Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Fernanda Batistel
- Department of Animal Sciences, University of Florida, Gainesville, FL 32608, USA;
| | - Claudia Parys
- Evonik Operations GmbH, Hanau-Wolfgang, 63457 Essen, Germany; (C.P.); (J.G.)
| | - Jessie Guyader
- Evonik Operations GmbH, Hanau-Wolfgang, 63457 Essen, Germany; (C.P.); (J.G.)
| | - Juan J. Loor
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801, USA; (Q.J.); (N.W.)
- Correspondence:
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Yee SW, Giacomini KM. Emerging Roles of the Human Solute Carrier 22 Family. Drug Metab Dispos 2021; 50:DMD-MR-2021-000702. [PMID: 34921098 PMCID: PMC9488978 DOI: 10.1124/dmd.121.000702] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/22/2021] [Accepted: 12/08/2021] [Indexed: 11/22/2022] Open
Abstract
The human Solute Carrier 22 family (SLC22), also termed the organic ion transporter family, consists of 28 distinct multi-membrane spanning proteins, which phylogenetically cluster together according to their charge specificity for organic cations (OCTs), organic anions (OATs) and organic zwitterion/cations (OCTNs). Some SLC22 family members are well characterized in terms of their substrates, transport mechanisms and expression patterns, as well as their roles in human physiology and pharmacology, whereas others remain orphans with no known ligands. Pharmacologically, SLC22 family members play major roles as determinants of the absorption and disposition of many prescription drugs, and several including the renal transporters, OCT2, OAT1 and OAT3 are targets for many clinically important drug-drug interactions. In addition, mutations in some of these transporters (SLC22A5 (OCTN2) and SLC22A12 (URAT1) lead to rare monogenic disorders. Genetic polymorphisms in SLC22 transporters have been associated with common human disease, drug response and various phenotypic traits. Three members in this family were deorphaned in very recently: SLC22A14, SLC22A15 and SLC22A24, and found to transport specific compounds such as riboflavin (SLC22A14), anti-oxidant zwitterions (SLC22A15) and steroid conjugates (SLC22A24). Their physiologic and pharmacological roles need further investigation. This review aims to summarize the substrates, expression patterns and transporter mechanisms of individual SLC22 family members and their roles in human disease and drug disposition and response. Gaps in our understanding of SLC22 family members are described. Significance Statement In recent years, three members of the SLC22 family of transporters have been deorphaned and found to play important roles in the transport of diverse solutes. New research has furthered our understanding of the mechanisms, pharmacological roles, and clinical impact of SLC22 transporters. This minireview provides overview of SLC22 family members of their physiologic and pharmacologic roles, the impact of genetic variants in the SLC22 family on disease and drug response, and summary of recent studies deorphaning SLC22 family members.
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Affiliation(s)
- Sook Wah Yee
- Bioengineering and Therapeutic Sciences, Univerity of California, San Francisco, United States
| | - Kathleen M Giacomini
- Bioengineering and Therapeutic Sciences, Univerity of California, San Francisco, United States
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Sun D, Chen Q, Gai Z, Zhang F, Yang X, Hu W, Chen C, Yang G, Hörmann S, Kullak-Ublick GA, Visentin M. The Role of the Carnitine/Organic Cation Transporter Novel 2 in the Clinical Outcome of Patients With Locally Advanced Esophageal Carcinoma Treated With Oxaliplatin. Front Pharmacol 2021; 12:684545. [PMID: 34603016 PMCID: PMC8481660 DOI: 10.3389/fphar.2021.684545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/18/2021] [Indexed: 01/25/2023] Open
Abstract
Esophageal cancer is the ninth most common malignancy worldwide, ranking sixth in mortality. Platinum-based chemotherapy is commonly used for treating locally advanced esophageal cancer, yet it is ineffective in a large portion of patients. There is a need for reliable molecular markers with direct clinical application for a prospective selection of patients who can benefit from chemotherapy and patients in whom toxicity is likely to outweigh the benefit. The cytotoxic activity of platinum derivatives largely depends on the uptake and accumulation into cells, primarily by organic cation transporters (OCTs). The aim of the study was to investigate the impact of OCT expression on the clinical outcome of patients with esophageal cancer treated with oxaliplatin. Twenty patients with esophageal squamous cell carcinoma (SCC) were prospectively enrolled and surgical specimens used for screening OCT expression level by western blotting and/or immunostaining, and for culture of cancer cells. Sixty-seven patients with SCC who received oxaliplatin and for whom follow-up was available were retrospectively assessed for organic cation/carnitine transporter 2 (OCTN2) expression by real time RT-PCR and immunostaining. OCTN2 staining was also performed in 22 esophageal adenocarcinomas. OCTN2 function in patient-derived cancer cells was evaluated by assessing L-carnitine uptake and sensitivity to oxaliplatin. The impact of OCTN2 on oxaliplatin activity was also assessed in HEK293 cells overexpressing OCTN2. OCTN2 expression was higher in tumor than in normal tissues. In patient-derived cancer cells and HEK293 cells, the expression of OCTN2 sensitized to oxaliplatin. Patients treated with oxaliplatin who had high OCTN2 level in the tumor tissue had a reduced risk of recurrence and a longer survival time than those with low expression of OCTN2 in tumor tissue. In conclusion, OCTN2 is expressed in esophageal cancer and it is likely to contribute to the accumulation and cytotoxic activity of oxaliplatin in patients with esophageal carcinoma treated with oxaliplatin.
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Affiliation(s)
- Dongfeng Sun
- Department of Thoracic Surgery, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Emergency Medicine, Shandong Lung Cancer Institute, Shandong Institute of Respiratory Diseases, Jinan, China
| | - Qingfa Chen
- The Institute for Tissue Engineering and Regenerative Medicine, Liaocheng University/Liaocheng People's Hospital, Liaocheng, China
| | - Zhibo Gai
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Fengxia Zhang
- Department of Thoracic Surgery, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Emergency Medicine, Shandong Lung Cancer Institute, Shandong Institute of Respiratory Diseases, Jinan, China
| | - Xiaoqing Yang
- Department of Pathology, The First Affiliated Hospital of Shandong First Medical University and Shandong Provincial Qianfoshan Hospital, Jinan, China
| | - Wensi Hu
- Department of Thoracic Surgery, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Emergency Medicine, Shandong Lung Cancer Institute, Shandong Institute of Respiratory Diseases, Jinan, China
| | - Chengyu Chen
- Department of Thoracic Surgery, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Medicine and Health Key Laboratory of Emergency Medicine, Shandong Lung Cancer Institute, Shandong Institute of Respiratory Diseases, Jinan, China
| | - Guangjie Yang
- Department of Nuclear Medicine, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Severin Hörmann
- Department of Pathology and Molecular Pathology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gerd A Kullak-Ublick
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Michele Visentin
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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Gyawali A, Hyeon SJ, Ryu H, Kang YS. The Alteration of L-Carnitine Transport and Pretreatment Effect under Glutamate Cytotoxicity on Motor Neuron-Like NSC-34 Lines. Pharmaceutics 2021; 13:pharmaceutics13040551. [PMID: 33919926 PMCID: PMC8070968 DOI: 10.3390/pharmaceutics13040551] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/07/2021] [Accepted: 04/12/2021] [Indexed: 12/04/2022] Open
Abstract
L-Carnitine (LC) is essential for transporting fatty acids to the mitochondria for β-oxidation. This study was performed to examine the alteration of the LC transport system in wild type (WT, NSC-34/hSOD1WT) and mutant type (MT, NSC-34/hSOD1G93A) amyotrophic lateral sclerosis (ALS) models. The uptake of [3H]L-carnitine was dependent on time, temperature, concentration, sodium, pH, and energy in both cell lines. The Michaelis–Menten constant (Km) value as well as maximum transport velocity (Vmax) indicated that the MT cell lines showed the higher affinity and lower capacity transport system, compared to that of the WT cell lines. Additionally, LC uptake was inhibited by organic cationic compounds but unaffected by organic anions. OCTN1/slc22a4 and OCTN2/slc22a5 siRNA transfection study revealed both transporters are involved in LC transport in NSC-34 cell lines. Additionally, slc22a4 and slc22a5 was significantly decreased in mouse MT models compared with that in ALS WT littermate models in the immune-reactivity study. [3H]L-Carnitine uptake and mRNA expression pattern showed the pretreatment of LC and acetyl L-carnitine (ALC) attenuated glutamate induced neurotoxicity in NSC-34 cell lines. These findings indicate that LC and ALC supplementation can prevent the neurotoxicity and neuro-inflammation induced by glutamate in motor neurons.
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Affiliation(s)
- Asmita Gyawali
- College of Pharmacy and Drug Information Research Institute, Sookmyung Women’s University, Seoul 04310, Korea;
| | - Seung Jae Hyeon
- Laboratory for Brain Gene Regulation and Epigenetics, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea; (S.J.H.); (H.R.)
| | - Hoon Ryu
- Laboratory for Brain Gene Regulation and Epigenetics, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea; (S.J.H.); (H.R.)
| | - Young-Sook Kang
- College of Pharmacy and Drug Information Research Institute, Sookmyung Women’s University, Seoul 04310, Korea;
- Correspondence: ; Tel.: +82-2-710-9562; Fax: +82-2-710-9871
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Li X, Wang H, Zhu Y, Cao W, Song M, Wang Y, Hou H, Lang M, Guo X, Tan X, Han JJ, Wang W. Heritability Enrichment of Immunoglobulin G N-Glycosylation in Specific Tissues. Front Immunol 2021; 12:741705. [PMID: 34804021 PMCID: PMC8595136 DOI: 10.3389/fimmu.2021.741705] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 10/12/2021] [Indexed: 02/05/2023] Open
Abstract
Genome-wide association studies (GWAS) have identified over 60 genetic loci associated with immunoglobulin G (IgG) N-glycosylation; however, the causal genes and their abundance in relevant tissues are uncertain. Leveraging data from GWAS summary statistics for 8,090 Europeans, and large-scale expression quantitative trait loci (eQTL) data from the genotype-tissue expression of 53 types of tissues (GTEx v7), we derived a linkage disequilibrium score for the specific expression of genes (LDSC-SEG) and conducted a transcriptome-wide association study (TWAS). We identified 55 gene associations whose predicted levels of expression were significantly associated with IgG N-glycosylation in 14 tissues. Three working scenarios, i.e., tissue-specific, pleiotropic, and coassociated, were observed for candidate genetic predisposition affecting IgG N-glycosylation traits. Furthermore, pathway enrichment showed several IgG N-glycosylation-related pathways, such as asparagine N-linked glycosylation, N-glycan biosynthesis and transport to the Golgi and subsequent modification. Through phenome-wide association studies (PheWAS), most genetic variants underlying TWAS hits were found to be correlated with health measures (height, waist-hip ratio, systolic blood pressure) and diseases, such as systemic lupus erythematosus, inflammatory bowel disease, and Parkinson's disease, which are related to IgG N-glycosylation. Our study provides an atlas of genetic regulatory loci and their target genes within functionally relevant tissues, for further studies on the mechanisms of IgG N-glycosylation and its related diseases.
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Affiliation(s)
- Xingang Li
- Centre for Precision Health, Edith Cowan University, Joondalup, WA, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
| | - Hao Wang
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
- Beijing Key Laboratory of Clinical Epidemiology, School of Public Health, Capital Medical University, Beijing, China
| | - Yahong Zhu
- Beijing Lucidus Bioinformation Technology Co., Ltd., Beijing, China
| | - Weijie Cao
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
- Beijing Key Laboratory of Clinical Epidemiology, School of Public Health, Capital Medical University, Beijing, China
| | - Manshu Song
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
- Beijing Key Laboratory of Clinical Epidemiology, School of Public Health, Capital Medical University, Beijing, China
| | - Youxin Wang
- Beijing Key Laboratory of Clinical Epidemiology, School of Public Health, Capital Medical University, Beijing, China
| | - Haifeng Hou
- School of Public Health, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai’an, China
| | - Minglin Lang
- Chinese Academy of Sciences (CAS) Center for Excellence in Biotic Interactions, College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Xiuhua Guo
- Beijing Key Laboratory of Clinical Epidemiology, School of Public Health, Capital Medical University, Beijing, China
| | - Xuerui Tan
- The First Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Jingdong J. Han
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Center for Quantitative Biology (CQB), Peking University, Beijing, China
| | - Wei Wang
- Centre for Precision Health, Edith Cowan University, Joondalup, WA, Australia
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia
- Beijing Key Laboratory of Clinical Epidemiology, School of Public Health, Capital Medical University, Beijing, China
- School of Public Health, Shandong First Medical University & Shandong Academy of Medical Sciences, Tai’an, China
- The First Affiliated Hospital, Shantou University Medical College, Shantou, China
- *Correspondence: Wei Wang,
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Zhang L, Gui T, Console L, Scalise M, Indiveri C, Hausler S, Kullak-Ublick GA, Gai Z, Visentin M. Cholesterol stimulates the cellular uptake of L-carnitine by the carnitine/organic cation transporter novel 2 (OCTN2). J Biol Chem 2020; 296:100204. [PMID: 33334877 PMCID: PMC7948396 DOI: 10.1074/jbc.ra120.015175] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 12/14/2020] [Accepted: 12/17/2020] [Indexed: 12/19/2022] Open
Abstract
The carnitine/organic cation transporter novel 2 (OCTN2) is responsible for the cellular uptake of carnitine in most tissues. Being a transmembrane protein OCTN2 must interact with the surrounding lipid microenvironment to function. Among the main lipid species that constitute eukaryotic cells, cholesterol has highly dynamic levels under a number of physiopathological conditions. This work describes how plasma membrane cholesterol modulates OCTN2 transport of L-carnitine in human embryonic kidney 293 cells overexpressing OCTN2 (OCTN2-HEK293) and in proteoliposomes harboring human OCTN2. We manipulated the cholesterol content of intact cells, assessed by thin layer chromatography, through short exposures to empty and/or cholesterol-saturated methyl-β-cyclodextrin (mβcd), whereas free cholesterol was used to enrich reconstituted proteoliposomes. We measured OCTN2 transport using [3H]L-carnitine, and expression levels and localization by surface biotinylation and Western blotting. A 20-min preincubation with mβcd reduced the cellular cholesterol content and inhibited L-carnitine influx by 50% in comparison with controls. Analogously, the insertion of cholesterol in OCTN2-proteoliposomes stimulated L-carnitine uptake in a dose-dependent manner. Carnitine uptake in cells incubated with empty mβcd and cholesterol-saturated mβcd to preserve the cholesterol content was comparable with controls, suggesting that the mβcd effect on OCTN2 was cholesterol dependent. Cholesterol stimulated L-carnitine influx in cells by markedly increasing the affinity for L-carnitine and in proteoliposomes by significantly enhancing the affinity for Na+ and, in turn, the L-carnitine maximal transport capacity. Because of the antilipogenic and antioxidant features of L-carnitine, the stimulatory effect of cholesterol on L-carnitine uptake might represent a novel protective effect against lipid-induced toxicity and oxidative stress.
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Affiliation(s)
- Lu Zhang
- College of Traditional Chinese Medicine, Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China; Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Ting Gui
- College of Traditional Chinese Medicine, Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Lara Console
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria, Arcavacata di Rende, Italy
| | - Stephanie Hausler
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gerd A Kullak-Ublick
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland; Mechanistic Safety, CMO & Patient Safety, Global Drug Development, Novartis Pharma, Basel, Switzerland
| | - Zhibo Gai
- College of Traditional Chinese Medicine, Innovation Research Institute of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan, China; Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
| | - Michele Visentin
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
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Organic Cation Transporters in Human Physiology, Pharmacology, and Toxicology. Int J Mol Sci 2020; 21:ijms21217890. [PMID: 33114309 PMCID: PMC7660683 DOI: 10.3390/ijms21217890] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/13/2022] Open
Abstract
Individual cells and epithelia control the chemical exchange with the surrounding environment by the fine-tuned expression, localization, and function of an array of transmembrane proteins that dictate the selective permeability of the lipid bilayer to small molecules, as actual gatekeepers to the interface with the extracellular space. Among the variety of channels, transporters, and pumps that localize to cell membrane, organic cation transporters (OCTs) are considered to be extremely relevant in the transport across the plasma membrane of the majority of the endogenous substances and drugs that are positively charged near or at physiological pH. In humans, the following six organic cation transporters have been characterized in regards to their respective substrates, all belonging to the solute carrier 22 (SLC22) family: the organic cation transporters 1, 2, and 3 (OCT1–3); the organic cation/carnitine transporter novel 1 and 2 (OCTN1 and N2); and the organic cation transporter 6 (OCT6). OCTs are highly expressed on the plasma membrane of polarized epithelia, thus, playing a key role in intestinal absorption and renal reabsorption of nutrients (e.g., choline and carnitine), in the elimination of waste products (e.g., trimethylamine and trimethylamine N-oxide), and in the kinetic profile and therapeutic index of several drugs (e.g., metformin and platinum derivatives). As part of the Special Issue Physiology, Biochemistry, and Pharmacology of Transporters for Organic Cations, this article critically presents the physio-pathological, pharmacological, and toxicological roles of OCTs in the tissues in which they are primarily expressed.
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Abstract
The organic cation transporters (OCTs) OCT1, OCT2, OCT3, novel OCT (OCTN)1, OCTN2, multidrug and toxin exclusion (MATE)1, and MATE kidney-specific 2 are polyspecific transporters exhibiting broadly overlapping substrate selectivities. They transport organic cations, zwitterions, and some uncharged compounds and operate as facilitated diffusion systems and/or antiporters. OCTs are critically involved in intestinal absorption, hepatic uptake, and renal excretion of hydrophilic drugs. They modulate the distribution of endogenous compounds such as thiamine, L-carnitine, and neurotransmitters. Sites of expression and functions of OCTs have important impact on energy metabolism, pharmacokinetics, and toxicity of drugs, and on drug-drug interactions. In this work, an overview about the human OCTs is presented. Functional properties of human OCTs, including identified substrates and inhibitors of the individual transporters, are described. Sites of expression are compiled, and data on regulation of OCTs are presented. In addition, genetic variations of OCTs are listed, and data on their impact on transport, drug treatment, and diseases are reported. Moreover, recent data are summarized that indicate complex drug-drug interaction at OCTs, such as allosteric high-affinity inhibition of transport and substrate dependence of inhibitor efficacies. A hypothesis about the molecular mechanism of polyspecific substrate recognition by OCTs is presented that is based on functional studies and mutagenesis experiments in OCT1 and OCT2. This hypothesis provides a framework to imagine how observed complex drug-drug interactions at OCTs arise. Finally, preclinical in vitro tests that are performed by pharmaceutical companies to identify interaction of novel drugs with OCTs are discussed. Optimized experimental procedures are proposed that allow a gapless detection of inhibitory and transported drugs.
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Affiliation(s)
- Hermann Koepsell
- Institute of Anatomy and Cell Biology and Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, University of Würzburg, Würzburg, Germany
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13
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Wang G, Zhao L, Jiang Q, Sun Y, Zhao D, Sun M, He Z, Sun J, Wang Y. Intestinal OCTN2- and MCT1-targeted drug delivery to improve oral bioavailability. Asian J Pharm Sci 2020; 15:158-173. [PMID: 32256846 PMCID: PMC7118283 DOI: 10.1016/j.ajps.2020.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 12/08/2019] [Accepted: 02/12/2020] [Indexed: 12/18/2022] Open
Abstract
Various drug transporters are widely expressed throughout the intestine and play important roles in absorbing nutrients and drugs, thus providing high quality targets for the design of prodrugs or nanoparticles to facilitate oral drug delivery. In particular, intestinal carnitine/organic cation transporter 2 (OCTN2) and mono-carboxylate transporter protein 1 (MCT1) possess high transport capacities and complementary distributions. Therefore, we outline recent developments in transporter-targeted oral drug delivery with regard to the OCTN2 and MCT1 proteins in this review. First, basic information of the two transporters is reviewed, including their topological structures, characteristics and functions, expression and key features of their substrates. Furthermore, progress in transporter-targeting prodrugs and nanoparticles to increase oral drug delivery is discussed, including improvements in the oral absorption of anti-inflammatory drugs, antiepileptic drugs and anticancer drugs. Finally, the potential of a dual transporter-targeting strategy is discussed.
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Affiliation(s)
- Gang Wang
- Zhuang Yao Medicine Center of Engineering and Technology, Guang Xi University of Chinese Medicine, Nanning 530200, China
| | - Lichun Zhao
- Zhuang Yao Medicine Center of Engineering and Technology, Guang Xi University of Chinese Medicine, Nanning 530200, China.,School of Pharmacy, Guang Xi University of Chinese Medicine, Nanning 530200, China
| | - Qikun Jiang
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Yixin Sun
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Dongyang Zhao
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Mengchi Sun
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Zhonggui He
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Jin Sun
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Yang Wang
- School of Pharmacy, Guang Xi University of Chinese Medicine, Nanning 530200, China
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15
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Effect of lifelong carnitine supplementation on plasma and tissue carnitine status, hepatic lipid metabolism and stress signalling pathways and skeletal muscle transcriptome in mice at advanced age. Br J Nutr 2019; 121:1323-1333. [DOI: 10.1017/s0007114519000709] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
AbstractWhile strong evidence from clinical studies suggests beneficial effects of carnitine supplementation on metabolic health, serious safety concerns associated with carnitine supplementation have been raised from studies in mice. Considering that the carnitine doses in these mice studies were up to 100 times higher than those used in clinical studies, the present study aimed to address possible safety concerns associated with long-term supplementation of a carnitine dose used in clinical trials. Two groups of NMRI mice were fed either a control or a carnitine-supplemented diet (1 g/kg diet) from weaning to 19 months of age, and parameters of hepatic lipid metabolism and stress signalling and skeletal muscle gene expression were analysed in the mice at 19 months of age. Concentrations of free carnitine and acetylcarnitine in plasma and tissues were higher in the carnitine than in the control group (P<0·05). Plasma concentrations of free carnitine and acetylcarnitine were higher in mice at adult age (10 and 15 months) than at advanced age (19 months) (P<0·05). Hepatic mRNA and protein levels of genes involved in lipid metabolism and stress signalling and hepatic and plasma lipid concentrations did not differ between the carnitine and the control group. Skeletal muscle transcriptome analysis in 19-month-old mice revealed only a moderate regulation between carnitine and control group. Lifelong carnitine supplementation prevents an age-dependent impairment of plasma carnitine status, but safety concerns associated with long-term supplementation of carnitine at doses used in clinical trials can be considered as unfounded.
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16
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Ringseis R, Keller J, Eder K. Basic mechanisms of the regulation of L-carnitine status in monogastrics and efficacy of L-carnitine as a feed additive in pigs and poultry. J Anim Physiol Anim Nutr (Berl) 2018; 102:1686-1719. [PMID: 29992642 DOI: 10.1111/jpn.12959] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/20/2018] [Accepted: 06/22/2018] [Indexed: 12/19/2022]
Abstract
A great number of studies have investigated the potential of L-carnitine as feed additive to improve performance of different monogastric and ruminant livestock species, with, however, discrepant outcomes. In order to understand the reasons for these discrepant outcomes, it is important to consider the determinants of L-carnitine status and how L-carnitine status is regulated in the animal's body. While it is a long-known fact that L-carnitine is endogenously biosynthesized in certain tissues, it was only recently recognized that critical determinants of L-carnitine status, such as intestinal L-carnitine absorption, tissue L-carnitine uptake, endogenous L-carnitine synthesis and renal L-carnitine reabsorption, are regulated by specific nutrient sensing nuclear receptors. This review aims to give a more in-depth understanding of the basic mechanisms of the regulation of L-carnitine status in monogastrics taking into account the most recent evidence on nutrient sensing nuclear receptors and evaluates the efficacy of L-carnitine as feed additive in monogastric livestock by providing an up-to-date overview about studies with L-carnitine supplementation in pigs and poultry.
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Affiliation(s)
- Robert Ringseis
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-University Gießen, Gießen, Germany
| | - Janine Keller
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-University Gießen, Gießen, Germany
| | - Klaus Eder
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-University Gießen, Gießen, Germany
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17
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Suzuki A, Sakai Y, Hashimoto K, Osawa H, Tsuruoka S. Kinetics of carnitine concentration after switching from oral administration to intravenous injection in hemodialysis patients. Ren Fail 2018; 40:196-200. [PMID: 29616582 PMCID: PMC6014372 DOI: 10.1080/0886022x.2018.1455587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Carnitine has high dialyzability and is often deficient in dialysis patients. This deficiency is treated by either intravenous (IV) or oral supplementation of carnitine. In this study, the mode of carnitine administration was changed from oral to IV in 17 hemodialysis (HD) patients, and the treatment was discontinued after 1 year. We found that the levels of total carnitine (TC), free-carnitine (FC), and acyl-carnitine (AC) significantly increased after 3 months of switching to IV administration (p < .05). After discontinuation of carnitine administration, the TC, FC, and AC levels decreased before dialysis. The average FC value was maintained at the normal levels until 9 months, but fell below the normal values when measured at the 12th month of discontinuation. In conclusion, carnitine was maintained at significantly high levels despite the smaller dose by IV infusion as compared with that by oral administration. We therefore suggest that our results be considered while determining both the carnitine administration route and the administration period in dialysis patients under clinical settings.
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Affiliation(s)
- Anna Suzuki
- a Department of Nephrology , Nippon Medical School Musashikosugi Hospital , Kawasaki , Japan.,b Department of Nephrology , Hakujikai Memorial Hospital , Tokyo , Japan
| | - Yukinao Sakai
- c Department of Nephrology, Graduate School of Medicine , Nippon Medical School , Tokyo , Japan
| | - Kazumasa Hashimoto
- b Department of Nephrology , Hakujikai Memorial Hospital , Tokyo , Japan.,c Department of Nephrology, Graduate School of Medicine , Nippon Medical School , Tokyo , Japan
| | - Hirokazu Osawa
- b Department of Nephrology , Hakujikai Memorial Hospital , Tokyo , Japan
| | - Shuichi Tsuruoka
- c Department of Nephrology, Graduate School of Medicine , Nippon Medical School , Tokyo , Japan
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18
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Servillo L, D'Onofrio N, Neglia G, Casale R, Cautela D, Marrelli M, Limone A, Campanile G, Balestrieri ML. Carnitine Precursors and Short-Chain Acylcarnitines in Water Buffalo Milk. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:8142-8149. [PMID: 30011990 DOI: 10.1021/acs.jafc.8b02963] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ruminants' milk contains δ-valerobetaine originating from rumen through the transformation of dietary Nε-trimethyllysine. Among ruminant's milk, the occurrence of δ-valerobetaine, along with carnitine precursors and metabolites, has not been investigated in buffalo milk, the second most worldwide consumed milk, well-known for its nutritional value. HPLC-ESI-MS/MS analyses of bulk milk revealed that the Italian Mediterranean buffalo milk contains δ-valerobetaine at levels higher than those in bovine milk. Importantly, we detected also γ-butyrobetaine, the l-carnitine precursor, never described so far in any milk. Of interest, buffalo milk shows higher levels of acetylcarnitine, propionylcarnitine, butyrylcarnitine, isobutyrylcarnitine, and 3-methylbutyrylcarnitine (isovalerylcarnitine) than cow milk. Moreover, buffalo milk shows isobutyrylcarnitine and butyrylcarnitine at a 1-to-1 molar ratio, while in cow's milk this ratio is 5 to 1. Results indicate a peculiar short-chain acylcarnitine profile characterizing buffalo milk, widening the current knowledge about its composition and nutritional value.
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Affiliation(s)
- Luigi Servillo
- Department of Precision Medicine , University of Campania "L. Vanvitelli" , 80138 Naples , Italy
| | - Nunzia D'Onofrio
- Department of Precision Medicine , University of Campania "L. Vanvitelli" , 80138 Naples , Italy
| | - Gianluca Neglia
- Department of Veterinary Medicine and Animal Production , Federico II University , 80137 Naples , Italy
| | - Rosario Casale
- Department of Precision Medicine , University of Campania "L. Vanvitelli" , 80138 Naples , Italy
| | - Domenico Cautela
- Stazione Sperimentale per le Industrie delle Essenze e dei derivati dagli Agrumi , Azienda Speciale della Camera di Commercio di Reggio Calabria , 89125 Reggio Calabria , Italy
| | - Massimo Marrelli
- Maxillofacial Surgery Section , Marrelli Health , 88900 Crotone , Italy
| | - Antonio Limone
- Istituto Zooprofilattico Sperimentale del Mezzogiorno , 80055 Naples , Italy
| | - Giuseppe Campanile
- Department of Veterinary Medicine and Animal Production , Federico II University , 80137 Naples , Italy
| | - Maria Luisa Balestrieri
- Department of Precision Medicine , University of Campania "L. Vanvitelli" , 80138 Naples , Italy
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19
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Ringseis R, Keller J, Eder K. Regulation of carnitine status in ruminants and efficacy of carnitine supplementation on performance and health aspects of ruminant livestock: a review. Arch Anim Nutr 2018; 72:1-30. [PMID: 29313385 DOI: 10.1080/1745039x.2017.1421340] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Carnitine has long been known to play a critical role for energy metabolism. Due to this, a large number of studies have been carried out to investigate the potential of supplemental carnitine in improving performance of livestock animals including ruminants, with however largely inconsistent results. An important issue that has to be considered when using carnitine as a feed additive is that the efficacy of supplemental carnitine is probably dependent on the animal's carnitine status, which is affected by endogenous carnitine synthesis, carnitine uptake from the gastrointestinal tract and carnitine excretion. The present review aims to summarise the current knowledge of the regulation of carnitine status and carnitine homeostasis in ruminants, and comprehensively evaluate the efficacy of carnitine supplementation on performance and/or health in ruminant livestock by comparing the outcomes of studies with carnitine supplementation in dairy cattle, growing and finishing cattle and sheep. While most of the studies show that supplemental carnitine, even in ruminally unprotected form, is bioavailable in ruminants, its effect on either milk or growth performance is largely disappointing. However, supplemental carnitine appears to be a useful strategy to offer protection against ammonia toxicity caused by consumption of high levels of non-protein N or forages with high levels of soluble N both, in cattle and sheep.
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Affiliation(s)
- Robert Ringseis
- a Institute of Animal Nutrition and Nutrition Physiology , Justus-Liebig-University Gießen , Gießen , Germany
| | - Janine Keller
- a Institute of Animal Nutrition and Nutrition Physiology , Justus-Liebig-University Gießen , Gießen , Germany
| | - Klaus Eder
- a Institute of Animal Nutrition and Nutrition Physiology , Justus-Liebig-University Gießen , Gießen , Germany
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20
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Usefulness of kidney slices for functional analysis of apical reabsorptive transporters. Sci Rep 2017; 7:12814. [PMID: 28993647 PMCID: PMC5634478 DOI: 10.1038/s41598-017-12828-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 09/15/2017] [Indexed: 02/02/2023] Open
Abstract
Kidney plays a key role in the elimination and reabsorption of drugs and nutrients, however in vitro methods to evaluate renal disposition are limited. In the present study, we investigated usefulness of isolated kidney slice, which had been used for transport only at basolateral membrane of tubular epithelial cells, for evaluation of apical membrane transporters. As transporters that are easy to discriminate between apical and basolateral transports, apical membrane specific and sodium-dependent transporters (SGLTs and OCTNs) and pH-dependent transporters (PEPTs) are selected. Uptake of ergothioneine, carnitine and methyl-α-D-glucopyranoside, which are substrates of apical Octn1, Octn2, and Sglt1/2, respectively, by mice kidney slices showed clear Na+ dependence and reduction by selective inhibitors. In addition, sodium dependence of ergothioneine uptake was negligible in the kidney slice from Octn1-gene deficient mice. Moreover, uptake of PepT1/2 substrate glycyl-sarcosine, was higher than that in the presence of glycyl-leucine, a non-specific Pept inhibitor. The Km and IC50 values for substrates and inhibitors of each transporter were mostly comparable to those obtained in transporter-transfected cells. In conclusion, it was demonstrated that kidney slices are promising tool to study transporters expressed at the apical membranes as well as basolateral membranes of kidney tubular epithelial cells.
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Kou L, Yao Q, Sun M, Wu C, Wang J, Luo Q, Wang G, Du Y, Fu Q, Wang J, He Z, Ganapathy V, Sun J. Cotransporting Ion is a Trigger for Cellular Endocytosis of Transporter-Targeting Nanoparticles: A Case Study of High-Efficiency SLC22A5 (OCTN2)-Mediated Carnitine-Conjugated Nanoparticles for Oral Delivery of Therapeutic Drugs. Adv Healthc Mater 2017; 6. [PMID: 28661032 DOI: 10.1002/adhm.201700165] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 04/21/2017] [Indexed: 01/16/2023]
Abstract
OCTN2 (SLC22A5) is a Na+ -coupled absorption transporter for l-carnitine in small intestine. This study tests the potential of this transporter for oral delivery of therapeutic drugs encapsulated in l-carnitine-conjugated poly(lactic-co-glycolic acid) (PLGA) nanoparticles (LC-PLGA NPs) and discloses the molecular mechanism for cellular endocytosis of transporter-targeting nanoparticles. Conjugation of l-carnitine to a surface of PLGA-NPs enhances the cellular uptake and intestinal absorption of encapsulated drug. In both cases, the uptake process is dependent on cotransporting ion Na+ . Computational OCTN2 docking analysis shows that the presence of Na+ is important for the formation of the energetically stable intermediate complex of transporter-Na+ -LC-PLGA NPs, which is also the first step in cellular endocytosis of nanoparticles. The transporter-mediated intestinal absorption of LC-PLGA NPs occurs via endocytosis/transcytosis rather than via the traditional transmembrane transport. The portal blood versus the lymphatic route is evaluated by the plasma appearance of the drug in the control and lymph duct-ligated rats. Absorption via the lymphatic system is the predominant route in the oral delivery of the NPs. In summary, LC-PLGA NPs can effectively target OCTN2 on the enterocytes for enhancing oral delivery of drugs and the critical role of cotransporting ions should be noticed in designing transporter-targeting nanoparticles.
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Affiliation(s)
- Longfa Kou
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
- Department of Cell Biology and Biochemistry; Texas Tech University Health Sciences Center; Lubbock TX 79430 USA
| | - Qing Yao
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
| | - Mengchi Sun
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
| | - Chunnuan Wu
- Tianjin Medical University Cancer Institute & Hospital; Tianjin 300060 China
| | - Jia Wang
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
| | - Qiuhua Luo
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
| | - Gang Wang
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
| | - Yuqian Du
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
| | - Qiang Fu
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
| | - Jian Wang
- Key Laboratory of Structure-Based Drug Design and Discovery; Shenyang Pharmaceutical University; Ministry of Education; Shenyang 110016 China
| | - Zhonggui He
- Department of Pharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; Shenyang 110016 China
| | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry; Texas Tech University Health Sciences Center; Lubbock TX 79430 USA
| | - Jin Sun
- Municipal Key Laboratory of Biopharmaceutics; School of Pharmacy; Shenyang Pharmaceutical University; No. 103 Wenhua Road Shenyang 110016 China
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Impairment of the carnitine/organic cation transporter 1-ergothioneine axis is mediated by intestinal transporter dysfunction in chronic kidney disease. Kidney Int 2017; 92:1356-1369. [PMID: 28754554 DOI: 10.1016/j.kint.2017.04.032] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 04/03/2017] [Accepted: 04/18/2017] [Indexed: 01/01/2023]
Abstract
Carnitine/organic cation transporter 1 (OCTN1) is a specific transporter of the food-derived antioxidant ergothioneine. Ergothioneine is absorbed by intestinal OCTN1, distributed through the bloodstream, and incorporated into each organ by OCTN1. OCTN1 expression is upregulated in injured tissues, and promotes ergothioneine uptake to reduce further damage caused by oxidative stress. However, the role of the OCTN1-ergothioneine axis in kidney-intestine cross-talk and chronic kidney disease (CKD) progression remains unclear. Here we assessed ergothioneine uptake via intestinal OCTN1 and confirmed the expression of OCTN1. The ability of OCTN1 to absorb ergothioneine was diminished in mice with CKD. In combination with OCTN1 dysfunction, OCTN1 localization on the intestinal apical cellular membrane was disturbed in mice with CKD. Proteomic analysis, RT-PCR, Western blotting, and immunohistochemistry revealed that PDZ (PSD95, Dlg, and ZO1), a PDZK1 domain-containing protein that regulates the localization of transporters, was decreased in mice with CKD. Decreased intestinal ergothioneine uptake from food decreased ergothioneine levels in the blood of mice with CKD. Despite increased OCTN1 expression and ergothioneine uptake into the kidneys of mice with CKD, ergothioneine levels did not increase. To identify the role of the OCTN1-ergothioneine axis in CKD, we evaluated kidney damage and oxidative stress in OCTN1-knockout mice with CKD and found that kidney fibrosis worsened. Oxidative stress indicators were increased in OCTN1-knockout mice. Moreover, ergothioneine levels in the blood of patients with CKD decreased, which were restored after kidney transplantation. Thus, a novel inter-organ interaction mediated by transporters is associated with CKD progression.
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Szabó K, Nagy Z, Juhász V, Zolnerciks JK, Csorba A, Tímár Z, Molnár É, Pádár P, Johnson W, Beéry E, Krajcsi P. Species specificity profiling of rat and human organic cation/carnitine transporter Slc22a5/SLC22A5 (Octn2/OCTN2). Drug Metab Pharmacokinet 2016; 32:165-171. [PMID: 28365301 DOI: 10.1016/j.dmpk.2016.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/25/2016] [Accepted: 08/18/2016] [Indexed: 01/09/2023]
Abstract
The purpose of this study was to characterize the uptake of carnitine, the physiological substrate, and the uptake of 3-(2,2,2-trimethylhydrazinium)propionate, a consensus substrate by rat Octn2 and human OCTN2 transporters as well as to characterize drug-mediated inhibition of l-carnitine uptake by the rat and human orthologs overexpressed in CHO-K1 cells. l-carnitine and 3-(2,2,2-trimethylhydrazinium)propionate were found to be a lower affinity substrate for rat Octn2 (KM = 32.66 ± 5.11 μM and 23.62 ± 4.99 μM respectively) than for human OCTN2 (KM = 3.08 ± 0.74 μM and 7.98 ± 0.63 μM). The intrinsic clearance (CLint) value for carnitine was higher for the human than for the rat transporter (22.82 ± 5.57 ml/min*mg vs 4.008 ± 0.675 ml/min*mg). For 3-(2,2,2-trimethylhydrazinium)propionate, in contrast, the CLint value for rat Octn2 was higher than for human OCTN2 (323.9 ± 72.8 ml/min*mg vs 65.11 ± 5.33 ml/min*mg). Furthermore, many pharmacologically important drugs were shown to affect l-carnitine transport by Octn2/OCTN2. The correlation between the IC50 datasets for the rat and human transporter resulted in an r value of 0.47 (p > 0.05). However, the greatest difference was less than seven-fold and 13 of 15 compounds yielded a difference less than 3-fold. Thus, the transporters from these two species showed an overlapping but somewhat different substrate and inhibitor specificity.
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Affiliation(s)
- Kitti Szabó
- SOLVO Biotechnology, 2 Gyár utca, Budaörs 2040, Hungary; SOLVO Biotechnology, 52 Közép fasor, Szeged 6726, Hungary.
| | - Zoltán Nagy
- SOLVO Biotechnology, 2 Gyár utca, Budaörs 2040, Hungary.
| | | | | | - Attila Csorba
- SOLVO Biotechnology, 52 Közép fasor, Szeged 6726, Hungary.
| | - Zoltán Tímár
- SOLVO Biotechnology, 52 Közép fasor, Szeged 6726, Hungary.
| | - Éva Molnár
- SOLVO Biotechnology, 52 Közép fasor, Szeged 6726, Hungary.
| | - Petra Pádár
- SOLVO Biotechnology, 52 Közép fasor, Szeged 6726, Hungary.
| | | | - Erzsébet Beéry
- SOLVO Biotechnology, 2 Gyár utca, Budaörs 2040, Hungary.
| | - Péter Krajcsi
- SOLVO Biotechnology, 2 Gyár utca, Budaörs 2040, Hungary.
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Intriguing possibilities and beneficial aspects of transporter-conscious drug design. Bioorg Med Chem 2015; 23:4119-4131. [PMID: 26138194 DOI: 10.1016/j.bmc.2015.06.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 06/02/2015] [Accepted: 06/10/2015] [Indexed: 01/11/2023]
Abstract
It has been revealed that many types of drugs interact with transporter proteins within an organism. Transporter proteins absorb or excrete materials, including drugs and nutrients, across the cell membrane. Some hydrophobic drugs are excreted from the cell as xenobiotics by ATP-binding cassette (ABC) transporters. However, solute carrier (SLC) transporters are tissue-specifically expressed and have substrate specificities. Thus, transporter-conscious drug design is an excellent method of delivering drugs to pharmaceutical target organs and provides advantages in absorption, distribution, excretion, and toxicity of drugs (ADMET) due to transport systems. In fact, based on this strategy, the bioavailability of prodrugs designed as peptide transporter 1 (PEPT1) substrates was better than that of the corresponding parent compounds due to the transport system in the small intestine. Furthermore, in central nervous system (CNS) drug developing, drug delivery into brain across the blood-brain barrier (BBB) is a serious problem. However, this problem can be also solved by the use of the transport systems at the BBB. Therefore, transporter-consciously designed drugs not only may effectively elicit activity but also may control adverse side effects caused by off-targets and drug-drug interactions and, consequently, may show good performance in clinical trials. In this review, I introduce possibilities and advantages of transporter-conscious drug designs.
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Luo H, Zhang Y, Guo H, Zhang L, Li X, Ringseis R, Wen G, Hui D, Liang A, Eder K, He D. Transcriptional regulation of the human, porcine and bovine OCTN2 gene by PPARα via a conserved PPRE located in intron 1. BMC Genet 2014; 15:90. [PMID: 25299939 PMCID: PMC4363911 DOI: 10.1186/s12863-014-0090-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 08/06/2014] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The novel organic cation transporter 2 (OCTN2) is the physiologically most important carnitine transporter in tissues and is responsible for carnitine absorption in the intestine, carnitine reabsorption in the kidney and distribution of carnitine between tissues. Genetic studies clearly demonstrated that the mouse OCTN2 gene is directly regulated by peroxisome proliferator-activated receptor α (PPARα). Despite its well conserved role as an important regulator of lipid catabolism in general, the specific genes under control of PPARα within each lipid metabolic pathway were shown to differ between species and it is currently unknown whether the OCTN2 gene is also a PPARα target gene in pig, cattle, and human. In the present study we examined the hypothesis that the porcine, bovine, and human OCTN2 gene are also PPARα target genes. RESULTS Using positional cloning and reporter gene assays we identified a functional PPRE, each in the intron 1 of the porcine, bovine, and human OCTN2 gene. Gel shift assay confirmed binding of PPARα to this PPRE in the porcine, bovine, and the human OCTN2 gene. CONCLUSIONS The results of the present study show that the porcine, bovine, and human OCTN2 gene, like the mouse OCTN2 gene, is directly regulated by PPARα. This suggests that regulation of genes involved in carnitine uptake by PPARα is highly conserved across species.
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Affiliation(s)
- Huidi Luo
- Institute of Animal Husbandry and Veterinary Medicine, Shanxi Provincial Academy of Agricultural Sciences, Taiyuan, 030031, P. R. China.
| | - Yuanqing Zhang
- Institute of Animal Husbandry and Veterinary Medicine, Shanxi Provincial Academy of Agricultural Sciences, Taiyuan, 030031, P. R. China.
| | - Huihui Guo
- Institute of Animal Husbandry and Veterinary Medicine, Shanxi Provincial Academy of Agricultural Sciences, Taiyuan, 030031, P. R. China.
| | - Li Zhang
- Institute of Animal Husbandry and Veterinary Medicine, Shanxi Provincial Academy of Agricultural Sciences, Taiyuan, 030031, P. R. China.
| | - Xi Li
- Institute of Animal Husbandry and Veterinary Medicine, Shanxi Provincial Academy of Agricultural Sciences, Taiyuan, 030031, P. R. China.
| | - Robert Ringseis
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-University Giessen, 35392, Giessen, Germany.
| | - Gaiping Wen
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-University Giessen, 35392, Giessen, Germany.
| | - Dequan Hui
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006, P. R. China.
| | - Aihua Liang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006, P. R. China.
| | - Klaus Eder
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-University Giessen, 35392, Giessen, Germany.
| | - Dongchang He
- Institute of Animal Husbandry and Veterinary Medicine, Shanxi Provincial Academy of Agricultural Sciences, Taiyuan, 030031, P. R. China.
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Sarlos P, Kovesdi E, Magyari L, Banfai Z, Szabo A, Javorhazy A, Melegh B. Genetic update on inflammatory factors in ulcerative colitis: Review of the current literature. World J Gastrointest Pathophysiol 2014; 5:304-21. [PMID: 25133031 PMCID: PMC4133528 DOI: 10.4291/wjgp.v5.i3.304] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/19/2014] [Accepted: 07/12/2014] [Indexed: 02/06/2023] Open
Abstract
Ulcerative colitis (UC) is one of the main types of inflammatory bowel disease, which is caused by dysregulated immune responses in genetically predisposed individuals. Several genetic factors, including interleukin and interleukin receptor gene polymorphisms and other inflammation-related genes play central role in mediating and modulating the inflammation in the human body, thereby these can be the main cause of development of the disease. It is clear these data are very important for understanding the base of the disease, especially in terms of clinical utility and validity, but summarized literature is exiguous for challenge health specialist that can used in the clinical practice nowadays. This review summarizes the current literature on inflammation-related genetic polymorphisms which are associated with UC. We performed an electronic search of Pubmed Database among publications of the last 10 years, using the following medical subject heading terms: UC, ulcerative colitis, inflammation, genes, polymorphisms, and susceptibility.
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Tang SC, Hendrikx JJMA, Beijnen JH, Schinkel AH. Genetically modified mouse models for oral drug absorption and disposition. Curr Opin Pharmacol 2013; 13:853-8. [PMID: 24021267 DOI: 10.1016/j.coph.2013.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/15/2013] [Accepted: 08/21/2013] [Indexed: 01/09/2023]
Abstract
Intestinal absorption is an essential step in the therapeutic use of most orally administered drugs and often mediated by enterocyte transmembrane transporters. Here we discuss several of these drug transport systems and knockout mouse models to study them. These studies showed that Multidrug resistance-associated protein 2 (Mrp2) can limit intestinal drug absorption. Organic cation transporter n1 (Octn1) and Octn2 might also facilitate intestinal drug absorption, although direct in vivo evidence is lacking. On the other hand, intestinal uptake of drugs is facilitated by the Equilibrative nucleoside transporter 1 (Ent1), Mrp3 and possibly Mrp4. No significant role in intestinal absorption for Oct1 and Oct2 or for Organic anion-transporting polypeptides (Oatp) 1a and 1b was found so far.
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Affiliation(s)
- Seng Chuan Tang
- Division of Molecular Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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Enzymes involved in L-carnitine biosynthesis are expressed by small intestinal enterocytes in mice: implications for gut health. J Crohns Colitis 2013; 7:e197-205. [PMID: 22999781 PMCID: PMC3644392 DOI: 10.1016/j.crohns.2012.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 08/01/2012] [Accepted: 08/19/2012] [Indexed: 02/08/2023]
Abstract
BACKGROUND Carnitine is essential for mitochondrial β-oxidation of long-chain fatty acids. Deficiency of carnitine leads to severe gut atrophy, ulceration and inflammation in animal models of carnitine deficiency. Genetic studies in large populations have linked mutations in the carnitine transporters OCTN1 and OCTN2 with Crohn's disease (CD), while other studies at the same time have failed to show a similar association and report normal serum carnitine levels in CD patients. METHODS In this report, we have studied the expression of carnitine-synthesizing enzymes in intestinal epithelial cells to determine the capability of these cells to synthesize carnitine de novo. We studied expression of five enzymes involved in carnitine biosynthesis, namely 6-N-trimethyllysine dioxygenase (TMLD), 4-trimethylaminobutyraldehyde dehydrogenase (TMABADH), serine hydroxymethyltransferase 1 and 2 (SHMT1 and 2) and γ-butyrobetaine hydroxylase (BBH) by real-time PCR in mice (C3H strain). We also measured activity of γ-BBH in the intestine using an ex vivo assay and localized its expression by in situ hybridization. RESULTS Our investigations show that mouse intestinal epithelium expresses all five enzymes required for de novo carnitine biosynthesis; the expression is localized mainly in villous surface epithelial cells throughout the intestine. The final rate-limiting enzyme γ-BBH is highly active in the small intestine; its activity was 9.7 ± 3.5 pmol/mg/min, compared to 22.7 ± 7.3 pmol/mg/min in the liver. CONCLUSIONS We conclude that mouse gut epithelium is able to synthesize carnitine de novo. This capacity to synthesize carnitine in the intestine may play an important role in gut health and can help explain lack of clinical carnitine deficiency signs in subjects with mutations with OCTN transporters.
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Reuter SE, Evans AM. Carnitine and acylcarnitines: pharmacokinetic, pharmacological and clinical aspects. Clin Pharmacokinet 2012; 51:553-72. [PMID: 22804748 DOI: 10.1007/bf03261931] [Citation(s) in RCA: 316] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
L-Carnitine (levocarnitine) is a naturally occurring compound found in all mammalian species. The most important biological function of L-carnitine is in the transport of fatty acids into the mitochondria for subsequent β-oxidation, a process which results in the esterification of L-carnitine to form acylcarnitine derivatives. As such, the endogenous carnitine pool is comprised of L-carnitine and various short-, medium- and long-chain acylcarnitines. The physiological importance of L-carnitine and its obligatory role in the mitochondrial metabolism of fatty acids has been clearly established; however, more recently, additional functions of the carnitine system have been described, including the removal of excess acyl groups from the body and the modulation of intracellular coenzyme A (CoA) homeostasis. In light of this, acylcarnitines cannot simply be considered by-products of the enzymatic carnitine transfer system, but provide indirect evidence of altered mitochondrial metabolism. Consequently, examination of the contribution of L-carnitine and acylcarnitines to the endogenous carnitine pool (i.e. carnitine pool composition) is critical in order to adequately characterize metabolic status. The concentrations of L-carnitine and its esters are maintained within relatively narrow limits for normal biological functioning in their pivotal roles in fatty acid oxidation and maintenance of free CoA availability. The homeostasis of carnitine is multifaceted with concentrations achieved and maintained by a combination of oral absorption, de novo biosynthesis, carrier-mediated distribution into tissues and extensive, but saturable, renal tubular reabsorption. Various disorders of carnitine insufficiency have been described but ultimately all result in impaired entry of fatty acids into the mitochondria and consequently disturbed lipid oxidation. Given the sensitivity of acylcarnitine concentrations and the relative carnitine pool composition in reflecting the intramitochondrial acyl-CoA to free CoA ratio (and, hence, any disturbances in mitochondrial metabolism), the relative contribution of L-carnitine and acylcarnitines within the total carnitine pool is therefore considered critical in the identification of mitochondria dysfunction. Although there is considerable research in the literature focused on disorders of carnitine insufficiency, relatively few have examined relative carnitine pool composition in these conditions; consequently, the complexity of these disorders may not be fully understood. Similarly, although important studies have been conducted establishing the pharmacokinetics of exogenous carnitine and short-chain carnitine esters in healthy volunteers, few studies have examined carnitine pharmacokinetics in patient groups. Furthermore, the impact of L-carnitine administration on the kinetics of acylcarnitines has not been established. Given the importance of L-carnitine as well as acylcarnitines in maintaining normal mitochondrial function, this review seeks to examine previous research associated with the homeostasis and pharmacokinetics of L-carnitine and its esters, and highlight potential areas of future research.
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Affiliation(s)
- Stephanie E Reuter
- School of Pharmacy Medical Sciences, University of South Australia, Adelaide, SA, Australia.
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Pochini L, Peta V, Indiveri C. Inhibition of the OCTN2 carnitine transporter by HgCl2and methylmercury in the proteoliposome experimental model: insights in the mechanism of toxicity. Toxicol Mech Methods 2012; 23:68-76. [DOI: 10.3109/15376516.2012.719166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Tamai I. Pharmacological and pathophysiological roles of carnitine/organic cation transporters (OCTNs: SLC22A4, SLC22A5 and Slc22a21). Biopharm Drug Dispos 2012; 34:29-44. [PMID: 22952014 DOI: 10.1002/bdd.1816] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 08/27/2012] [Accepted: 08/30/2012] [Indexed: 02/06/2023]
Abstract
The carnitine/organic cation transporter (OCTN) family consists of three transporter isoforms, i.e. OCTN1 (SLC22A4) and OCTN2 (SLC22A5) in humans and animals and Octn3 (Slc22a21) in mice. These transporters are physiologically essential to maintain appropriate systemic and tissue concentrations of carnitine by regulating its membrane transport during intestinal absorption, tissue distribution and renal reabsorption. Among them, OCTN2 is a sodium-dependent, high-affinity transporter of carnitine, and a functional defect of OCTN2 due to genetic mutation causes primary systemic carnitine deficiency (SCD). Since carnitine is essential for beta-oxidation of long-chain fatty acids to produce ATP, OCTN2 gene mutation causes a range of symptoms, including cardiomyopathy, skeletal muscle weakness, fatty liver and male infertility. These functional consequences of Octn2 gene mutation can be seen clearly in an animal model, jvs mouse, which exhibits the SCD phenotype. In addition, although the mechanism is not clear, single nucleotide polymorphisms of OCTN1 and OCTN2 genes are associated with increased incidences of rheumatoid arthritis, Crohn's disease and asthma. OCTN1 and OCTN2 accept cationic drugs as substrates and contribute to intestinal and pulmonary absorption, tissue distribution (including to tumour cells), and renal excretion of these drugs. Modulation of the transport activity of OCTN2 by externally administered drugs may cause drug-induced secondary carnitine deficiency. Rodent Octn3 transports carnitine specifically, particularly in male reproductive tissues. Thus, the OCTNs are physiologically, pathologically and pharmacologically important. Detailed characterization of these transporters will greatly improve our understanding of the pathology associated with common diseases caused by functional deficiency of OCTNs.
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Affiliation(s)
- Ikumi Tamai
- Faculty of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, 920-1192, Japan.
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Ling B, Aziz C, Alcorn J. Systematic Evaluation of Key L-Carnitine Homeostasis Mechanisms during Postnatal Development in Rat. Nutr Metab (Lond) 2012; 9:66. [PMID: 22805277 PMCID: PMC3408321 DOI: 10.1186/1743-7075-9-66] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 07/17/2012] [Indexed: 01/01/2023] Open
Abstract
Background The conditionally essential nutrient, L-carnitine, plays a critical role in a number of physiological processes vital to normal neonatal growth and development. We conducted a systematic evaluation of the developmental changes in key L-carnitine homeostasis mechanisms in the postnatal rat to better understand the interrelationship between these pathways and their correlation to ontogenic changes in L-carnitine levels during postnatal development. Methods mRNA expression of heart, kidney and intestinal L-carnitine transporters, liver γ-butyrobetaine hydroxylase (Bbh) and trimethyllysine hydroxylase (Tmlh), and heart carnitine palmitoyltransferase (Cpt) were measured using quantitative RT-PCR. L-Carnitine levels were determined by HPLC-UV. Cpt and Bbh activity were measured by a spectrophotometric method and HPLC, respectively. Results Serum and heart L-carnitine levels increased with postnatal development. Increases in serum L-carnitine correlated significantly with postnatal increases in renal organic cation/carnitine transporter 2 (Octn2) expression, and was further matched by postnatal increases in intestinal Octn1 expression and hepatic γ-Bbh activity. Postnatal increases in heart L-carnitine levels were significantly correlated to postnatal increases in heart Octn2 expression. Although cardiac high energy phosphate substrate levels remained constant through postnatal development, creatine showed developmental increases with advancing neonatal age. mRNA levels of Cpt1b and Cpt2 significantly increased at postnatal day 20, which was not accompanied by a similar increase in activity. Conclusions Several L-carnitine homeostasis pathways underwent significant ontogenesis during postnatal development in the rat. This information will facilitate future studies on factors affecting the developmental maturation of L-carnitine homeostasis mechanisms and how such factors might affect growth and development.
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Affiliation(s)
- Binbing Ling
- College of Pharmacy and Nutrition, University of Saskatchewan, 110 Science Place, Saskatoon, SK, S7N 5C9, Canada.
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Hu C, Lancaster CS, Zuo Z, Hu S, Chen Z, Rubnitz JE, Baker SD, Sparreboom A. Inhibition of OCTN2-mediated transport of carnitine by etoposide. Mol Cancer Ther 2012; 11:921-9. [PMID: 22389472 DOI: 10.1158/1535-7163.mct-11-0980] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OCTN2 is a bifunctional transporter that reabsorbs filtered carnitine in a sodium-dependent manner and secretes organic cations into urine as a proton antiport mechanism. We hypothesized that inhibition of OCTN2 by anticancer drugs can influence carnitine resorption. OCTN2-mediated transport inhibition by anticancer drugs was assessed using cells transfected with human OCTN2 (hOCTN2) or mouse Octn2 (mOctn2). Excretion of carnitine and acetylcarnitine was measured in urine collected from mice and pediatric patients with cancer before and after administration of etoposide. Five of 27 tested drugs (50-100 μmol/L) inhibited hOCTN2-mediated carnitine uptake by 42% to 85% (P < 0.001). Of these inhibitors, etoposide was itself a transported substrate of hOCTN2 and mOctn2. Etoposide uptake by hOCTN2 was reversed in the presence of excess carnitine. This competitive inhibitory mechanism was confirmed in an in silico molecular docking analysis. In addition, etoposide inhibited the transcellular apical-to-basolateral flux of carnitine in kidney cells. Etoposide was also associated with a significant urinary loss of carnitine in mice (~1.5-fold) and in patients with cancer (~2.4-fold). Collectively, these findings indicate that etoposide can inhibit hOCTN2 function, potentially disturb carnitine homeostasis, and that this phenomenon can contribute to treatment-related toxicities.
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Affiliation(s)
- Chaoxin Hu
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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Girardin M, Dionne S, Goyette P, Rioux J, Bitton A, Elimrani I, Charlebois P, Qureshi I, Levy E, Seidman EG. Expression and functional analysis of intestinal organic cation/L-carnitine transporter (OCTN) in Crohn's disease. J Crohns Colitis 2012; 6:189-97. [PMID: 22325173 DOI: 10.1016/j.crohns.2011.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 07/27/2011] [Accepted: 08/11/2011] [Indexed: 02/06/2023]
Abstract
BACKGROUND The IBD5 locus is a genetic risk factor for IBD, particularly Crohn's Disease, coding for the organic cation/carnitine transporters (OCTN1 and 2). Two variants of OCTN are associated with susceptibility to Crohn's Disease. Modified transport of carnitine in vitro has been reported for a polymorphism of OCTN1. The aim was to investigate the function of intestinal OCTNs in IBD in relation to genetic polymorphisms. METHODS Intestinal tissue was obtained from endoscopic biopsies and surgical resections from IBD patients (n=33 and 14, resp.) and controls (n=22 and 14, resp.). OCTN protein levels were measured in intestinal biopsies and carnitine transport was quantified in intestinal resections. RESULTS OCTN1 protein levels were significantly higher in ileal versus colonic tissue (2.95% ± 0.4 vs 0.66% ± 0.2, resp.; p<0.0002). OCTN1 expression was higher in Crohn's disease patients with mutant homozygous or heterozygous genotypes (0.6% ± 0.1 vs 3% ± 0.8, resp., p<0.02). Carnitine transport was very rapid and Na+ dependent (10s). It was not different comparing Crohn's Disease and control groups (0.45 ± 0.12 vs 0.51 ± 0.12 nM carnitine/mg prot/min, resp.). Carnitine transport tended to be higher in subjects with mutant homozygous and heterozygous OCTN1 and OCTN2 genotypes (0.19 vs 0.59 and 0.25 vs 0.6, respectively). CONCLUSIONS The present data reveal that OCTN protein levels appear to be similar in intestinal tissue from Crohn's Disease patients and controls. Overall, ileal carnitine transport appears to as well equal in Crohn's Disease and control groups. However, there was a trend towards higher carnitine transport in subjects with OCTN1 and OCTN2 mutations.
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Affiliation(s)
- Marc Girardin
- DigestiveLab, Research Institute, McGill University Health Centre, Montreal, QC, Canada.
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Mo JX, Shi SJ, Zhang Q, Gong T, Sun X, Zhang ZR. Synthesis, transport and mechanism of a type I prodrug: L-carnitine ester of prednisolone. Mol Pharm 2011; 8:1629-40. [PMID: 21854030 DOI: 10.1021/mp100412z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Aerosol glucocorticoid medications have become more and more important in treating BA (bronchial asthma). Although these agents are dosed to directly target airway inflammation, adrenocortical suppression and other systematic effects are still seen. To tackle this problem in a novel way, two L-carnitine ester derivatives of prednisolone (as the model drug), namely, PDC and PDSC, were synthesized to increase the absorption of prednisolone across the human bronchial epithelial BEAS-2B cells by the organic cation/carnitine transporter OCTN2 (SLC22A5) and then to slowly and intracellularly release prednisolone. The transport of prednisolone, PDC and PDSC into the human bronchial epithelial BEAS-2B cells was in the order PDSC > prednisolone > PDC at 37 °C. It was found that PDSC displayed 1.79-fold increase of uptake compared to prednisolone. Transport of PDSC by BEAS-2B was temperature-, time-, and Na(+)-dependent and saturable, with an apparent K(m) value of 329.74 μM, suggesting the involvement of carrier-mediated uptake. An RT-PCR study showed that organic cation/carnitine transporters OCTN1 and OCTN2 are expressed in BEAS-2B cells, but little in HEK293T cells. The order of uptake by HEK293T was prednisolone > PDC > PDSC. In addition, the inhibitory effects of organic cations such as L-carnitine, ergothioneine, TEA(+) and ipratropium on PDSC uptake in BEAS-2B cells were in the order L-carnitine > ipratropium > TEA(+) > ergothioneine, whereas their inhibitory effects on PDSC uptake in HEK293T cells were negligible. Finally, in vitro LPS-induced IL-6 production from BEAS-2B was more and longer suppressed by PDSC than prednisolone and PDC. All of these results suggested PDSC may be an attractive candidate for asthma treatment.
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Affiliation(s)
- Jing-xin Mo
- Key Laboratory of Drug Targeting and Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Sichuan 610041, PR China
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Sugiura T, Shimizu T, Kijima A, Minakata S, Kato Y. PDZ adaptors: their regulation of epithelial transporters and involvement in human diseases. J Pharm Sci 2011; 100:3620-35. [PMID: 21538352 DOI: 10.1002/jps.22575] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2011] [Revised: 03/28/2011] [Accepted: 03/31/2011] [Indexed: 12/17/2022]
Abstract
Homeostasis in the body is at least partially maintained by mechanisms that control membrane permeability, and thereby serve to control the uptake of essential substances (e.g., nutrients) and the efflux of unwanted substances (e.g., xenobiotics and metabolites) in epithelial cells. Various transporters play fundamental roles in such bidirectional transport, but little is known about how they are organized on plasma membranes. Protein-protein interactions may play a key role: several transporters in epithelial cells interact with the so-called adaptor proteins, which are membrane anchored and interact with both transporters and other membranous proteins. Although most of the evidences for transporter-adaptor interaction has been obtained in vitro, recent studies suggest that adaptor-mediated transporter regulation does occur in vivo and could be relevant to human diseases. Thus, protein-protein interaction is not only associated with the formation of macromolecular complexes but is also involved in various cellular events, and may provide transporters with additional functionality by forming transporter networks on plasma membranes. Interactions between xenobiotic transporters and PSD95/Dlg/ZO1 (PDZ) adaptors were previously reviewed by Kato and Tsuji (2006. Eur J Pharm Sci 27:487-500); the present review focuses on the latest findings about PDZ adaptors as regulators of transporter networks and their potential role in human diseases.
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Affiliation(s)
- Tomoko Sugiura
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-1192, Japan
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Wu W, Dnyanmote AV, Nigam SK. Remote communication through solute carriers and ATP binding cassette drug transporter pathways: an update on the remote sensing and signaling hypothesis. Mol Pharmacol 2011; 79:795-805. [PMID: 21325265 DOI: 10.1124/mol.110.070607] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Recent data from knockouts, human disease, and transport studies suggest that solute carrier (SLC) and ATP binding cassette (ABC) multispecific "drug" transporters maintain effective organ and body fluid concentrations of key nutrients, signaling molecules, and antioxidants. These processes involve transcellular movement of solutes across epithelial barriers and fluid compartments (e.g., blood, cerebrospinal fluid, urine, bile) via "matching" or homologous sets of SLC (e.g., SLC21, SLC22, SLC47) and ABC transporters. As described in the "Remote Sensing and Signaling Hypothesis" (Biochem Biophys Res Commun 323:429-436, 2004; Biochem Biophys Res Commun 351:872-876, 2006; J Biol Chem 282:23841-23853, 2007; Nat Clin Pract Nephrol 3:443-448, 2007; Mol Pharmacol 76:481-490, 2009), highly regulated transporter networks with overlapping substrate preferences are involved in sensing and signaling to maintain homeostasis in response to environmental changes (e.g., substrate imbalance and injury). They function in parallel with (and interact with) the endocrine and autonomic systems. Uric acid (urate), carnitine, prostaglandins, conjugated sex steroids, cGMP, odorants, and enterobiome metabolites are discussed here as examples. Xenobiotics hitchhike on endogenous carrier systems, sometimes leading to toxicity and side effects. By regulation of the expression and/or function of various remote organ multispecific transporters after injury, the overall transport capacity of the remote organ to handle endogenous toxins, metabolites, and signaling molecules may change, aiding in recovery. Moreover, these transporters may play a role in communication between organisms. The specific cellular components involved in sensing and altering transporter abundance or functionality depend upon the metabolite in question and probably involve different types of sensors as well as epigenetic regulation.
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Affiliation(s)
- Wei Wu
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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Diao L, Shu Y, Polli JE. Uptake of pramipexole by human organic cation transporters. Mol Pharm 2010; 7:1342-7. [PMID: 20496886 DOI: 10.1021/mp100036b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pramipexole is a hydrophilic, weakly basic drug, but exhibits high oral bioavailability in humans (>90%). In rats, rOct1 and rOct2 contribute toward pramipexole excretion into urine. The objective of this study was to assess whether pramipexole is a substrate for human OCT1-3. In vitro uptake studies were performed using hOCT1-MDCK monolayers, hOCT2-HEK cells and hOCT3-HEK cells. hOCT2 transported pramipexole in a high affinity manner (K(t) = 15.4 +/- 4.1 microM, J(max) = 0.476 +/- 0.028 pmol/s/cm(2)). hOCT3 transported pramipexole in a low affinity manner (K(t) = 138 +/- 31 microM, J(max) = 1.10 +/- 0.08 pmol/s/cm(2)). Although previously reported to be translocated by rOct1, pramipexole was not a substrate for hOCT1. The human intestinal absorption of pramipexole may involve transport by OCT3 and possibly OCT2. OCT2- and OCT3-mediated transport of pramipexole have implications in the drug's elimination from the kidney and distribution in the brain, respectively.
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Affiliation(s)
- Lei Diao
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201, USA
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Sugiura T, Otake T, Shimizu T, Wakayama T, Silver DL, Utsumi R, Nishimura T, Iseki S, Nakamichi N, Kubo Y, Tsuji A, Kato Y. PDZK1 regulates organic anion transporting polypeptide Oatp1a in mouse small intestine. Drug Metab Pharmacokinet 2010; 25:588-98. [PMID: 21084765 DOI: 10.2133/dmpk.dmpk-10-rg-074] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent studies indicate that various members of the organic anion transporting polypeptide (OATP) family are expressed on apical membranes of the small intestine. In the present study, we investigated possible interaction of Oatp with the PDZ protein PDZK1 in mouse small intestine, using [³H]estrone-3-sulfate (E3S) as a typical substrate. After intraduodenal administration, the level of [³H]E3S appearing in the portal vein of pdzk1 gene knockout (pdzk1(-/-)) mice was much lower than that in wild-type mice. Lower intestinal absorption of [³H]E3S in pdzk1(-/-) mice was confirmed in Ussing-type chamber experiments, which showed smaller uptake of [³H]E3S from the apical side in intestinal tissues of pdzk1(-/-) mice compared with wild-type mice. The kinetics and inhibition profile of [³H]E3S uptake in the Ussing-type chamber were similar to those in HEK293 cells stably expressing Oatp1a5, suggesting involvement of Oatp1a5 in [³H]E3S uptake. Immunoreactivity to anti-Oatp1a antibody was colocalized with PDZK1 in the small intestine of wild-type mice, whereas apical localization of Oatp1a protein was reduced in pdzk1(-/-) mice. An immunoprecipitation study revealed physical interaction of PDZK1 with Oatp1a. Thus, PDZK1 appears to act as an adaptor for Oatp1a. This is the first demonstration of a regulatory protein directly interacting with small-intestinal OATP.
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Affiliation(s)
- Tomoko Sugiura
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan
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Diao L, Ekins S, Polli JE. Quantitative structure activity relationship for inhibition of human organic cation/carnitine transporter. Mol Pharm 2010; 7:2120-31. [PMID: 20831193 DOI: 10.1021/mp100226q] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Organic cation/carnitine transporter (OCTN2; SLC22A5) is an important transporter for L-carnitine homeostasis, but can be inhibited by drugs, which may cause L-carnitine deficiency and possibly other OCTN2-mediated drug-drug interactions. One objective was to develop a quantitative structure-activity relationship (QSAR) of OCTN2 inhibitors, in order to predict and identify other potential OCTN2 inhibitors and infer potential clinical interactions. A second objective was to assess two high renal clearance drugs that interact with OCTN2 in vitro (cetirizine and cephaloridine) for possible OCTN2-mediated drug-drug interactions. Using previously generated in vitro data of 22 drugs, a 3D quantitative pharmacophore model and a Bayesian machine learning model were developed. The four pharmacophore features include two hydrophobic groups, one hydrogen-bond acceptor, and one positive ionizable center. The Bayesian machine learning model was developed using simple interpretable descriptors and function class fingerprints of maximum diameter 6 (FCFP_6). An external test set of 27 molecules, including 15 newly identified OCTN2 inhibitors, and a literature test set of 22 molecules were used to validate both models. The computational models afforded good capability to identify structurally diverse OCTN2 inhibitors, providing a valuable tool to predict new inhibitors efficiently. Inhibition results confirmed our previously observed association between rhabdomyolysis and C(max)/K(i) ratio. The two high renal clearance drugs cetirizine and cephaloridine were found not to be OCTN2 substrates, and their diminished elimination by other drugs is concluded not to be mediated by OCTN2.
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Affiliation(s)
- Lei Diao
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 20 Penn Street, Baltimore, Maryland 21201, USA
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Sugiura T, Kato S, Shimizu T, Wakayama T, Nakamichi N, Kubo Y, Iwata D, Suzuki K, Soga T, Asano M, Iseki S, Tamai I, Tsuji A, Kato Y. Functional expression of carnitine/organic cation transporter OCTN1/SLC22A4 in mouse small intestine and liver. Drug Metab Dispos 2010; 38:1665-72. [PMID: 20601551 DOI: 10.1124/dmd.110.032763] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Carnitine/organic cation transporter (OCTN1/SLC22A4) accepts various therapeutic agents as substrates in vitro and is expressed ubiquitously, although its function in most organs has not yet been examined. The purpose of the present study was to evaluate functional expression of OCTN1 in small intestine and liver, using octn1 gene knockout [octn1(-/-)] mice. After oral administration of [(3)H]ergothioneine ([(3)H]ERGO), a typical substrate of OCTN1, the amount of [(3)H]ERGO remaining in the small intestinal lumen was much higher in octn1(-/-) mice than in wild-type mice. In addition, uptake of [(3)H]ERGO by human embryonic kidney 293 cells heterologously expressing OCTN1 gene product and uptake of [(3)H]ERGO at the apical surface of intestinal everted sacs from wild-type mice were inhibited by OCTN1 substrates, tetraethylammonium and verapamil. Immunohistochemical analysis revealed that OCTN1 is localized on the apical surface of small intestine in mice and humans. These results suggest that OCTN1 is responsible for small intestinal absorption of [(3)H]ERGO. However, the plasma concentration of [(3)H]ERGO after oral administration was higher in octn1(-/-) mice than in wild-type mice, despite the lower absorption in octn1(-/-) mice. This was probably because of efficient hepatic uptake of [(3)H]ERGO, as revealed by integration plot analysis; the uptake clearance was close to the hepatic plasma flow rate. The uptake of [(3)H]ERGO by isolated hepatocytes was minimal, whereas [(3)H]ERGO uptake was observed in isolated nonparenchymal cells. This finding is consistent with immunostaining of OCTN1 in liver sinusoids. Thus, our results indicate that OCTN1 is functionally expressed in nonparenchymal liver cells.
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Affiliation(s)
- Tomoko Sugiura
- Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Japan
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Lin Z, Nelson L, Franke A, Poritz L, Li TY, Wu R, Wang Y, MacNeill C, Thomas NJ, Schreiber S, Koltun WA. OCTN1 variant L503F is associated with familial and sporadic inflammatory bowel disease. J Crohns Colitis 2010; 4:132-8. [PMID: 21122496 DOI: 10.1016/j.crohns.2009.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 09/07/2009] [Accepted: 09/08/2009] [Indexed: 02/07/2023]
Abstract
PURPOSE A two-allele haplotype of TC (OCTN1 rs1050152 and OCTN2 -207G→C) is associated with Crohn's disease (CD). The association has been replicated in different populations, but also failed in some studies. The present study is to replicate the association of OCTN1 rs1050152 and examine another variant rs272879 with familial and sporadic inflammatory bowel disease (IBD) in a cohort from central Pennsylvania, USA. METHODS The study samples (n=465) included 212 inflammatory bowel disease patients (CD=115, UC=97), including 103 familial (CD=55, UC=46) and 111 sporadic (CD=60, UC=51) IBD, 139 non-IBD family members from a familial IBD registry, and 114 unrelated healthy controls. A total of 12 OCTN1 variants within exonic sequences were examined. Two nonsynonymous SNPs, rs1050152 (L503F) and rs272879 (L395V) were genotyped by a PCR-based RFLP/cRFLP method and statistically analyzed. These samples with an additional 141 unrelated healthy samples were also genotyped for rs1050152 using the SNPlex™ Genotyping System. RESULTS The OCTN1 rs1050152 is associated with CD (OR=1.745, 95% CI=1.019-2.990, χ²=4.129, p=0.042) and with IBD (OR=1.68, 95% CI=1.052-2.676, χ²=4.732, p=0.030); while the variant rs272879 is not associated with IBD, CD or ulcerative colitis (UC). The distribution of the rs1050152 variant showed a high level of the T allele in male UC (OR=2.585, 95% CI=1.139-5.869, p=0.023) and IBD (OR=2.039, 95% CI=1.024-4.059, p=0.042) patients, and in female CD patients (OR=2.329, 95% CI=1.038-5.226, ρ value=0.039). CONCLUSION The present results replicated the association of the OCTN1 rs1050152 (L503F) variant with CD and IBD overall. A weak gender-specific effect of rs1050152 (L503F) on male UC and female CD was observed.
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Affiliation(s)
- Zhenwu Lin
- Department of Surgery, The Pennsylvania State University, College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
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Klaassen CD, Aleksunes LM. Xenobiotic, bile acid, and cholesterol transporters: function and regulation. Pharmacol Rev 2010; 62:1-96. [PMID: 20103563 PMCID: PMC2835398 DOI: 10.1124/pr.109.002014] [Citation(s) in RCA: 563] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transporters influence the disposition of chemicals within the body by participating in absorption, distribution, and elimination. Transporters of the solute carrier family (SLC) comprise a variety of proteins, including organic cation transporters (OCT) 1 to 3, organic cation/carnitine transporters (OCTN) 1 to 3, organic anion transporters (OAT) 1 to 7, various organic anion transporting polypeptide isoforms, sodium taurocholate cotransporting polypeptide, apical sodium-dependent bile acid transporter, peptide transporters (PEPT) 1 and 2, concentrative nucleoside transporters (CNT) 1 to 3, equilibrative nucleoside transporter (ENT) 1 to 3, and multidrug and toxin extrusion transporters (MATE) 1 and 2, which mediate the uptake (except MATEs) of organic anions and cations as well as peptides and nucleosides. Efflux transporters of the ATP-binding cassette superfamily, such as ATP-binding cassette transporter A1 (ABCA1), multidrug resistance proteins (MDR) 1 and 2, bile salt export pump, multidrug resistance-associated proteins (MRP) 1 to 9, breast cancer resistance protein, and ATP-binding cassette subfamily G members 5 and 8, are responsible for the unidirectional export of endogenous and exogenous substances. Other efflux transporters [ATPase copper-transporting beta polypeptide (ATP7B) and ATPase class I type 8B member 1 (ATP8B1) as well as organic solute transporters (OST) alpha and beta] also play major roles in the transport of some endogenous chemicals across biological membranes. This review article provides a comprehensive overview of these transporters (both rodent and human) with regard to tissue distribution, subcellular localization, and substrate preferences. Because uptake and efflux transporters are expressed in multiple cell types, the roles of transporters in a variety of tissues, including the liver, kidneys, intestine, brain, heart, placenta, mammary glands, immune cells, and testes are discussed. Attention is also placed upon a variety of regulatory factors that influence transporter expression and function, including transcriptional activation and post-translational modifications as well as subcellular trafficking. Sex differences, ontogeny, and pharmacological and toxicological regulation of transporters are also addressed. Transporters are important transmembrane proteins that mediate the cellular entry and exit of a wide range of substrates throughout the body and thereby play important roles in human physiology, pharmacology, pathology, and toxicology.
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Affiliation(s)
- Curtis D Klaassen
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160-7417, USA.
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The role of peroxisome proliferator-activated receptor α in transcriptional regulation of novel organic cation transporters. Eur J Pharmacol 2010; 628:1-5. [DOI: 10.1016/j.ejphar.2009.11.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Revised: 11/08/2009] [Accepted: 11/17/2009] [Indexed: 12/26/2022]
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Ardesjö B, Portela-Gomes GM, Rorsman F, Grimelius L, Ekwall O. Identification of a novel staining pattern of bile duct epithelial cells in primary sclerosing cholangitis. Inflamm Bowel Dis 2010; 16:305-11. [PMID: 19653288 DOI: 10.1002/ibd.21050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Primary sclerosing cholangitis (PSC) is an inflammatory disease of the bile ducts with an unknown etiology. A number of autoantigens have been proposed, but an early diagnostic marker is still lacking. Our aim was to identify such an autoantigen. METHODS Immunostaining was performed on normal human bile duct with sera from patients with PSC and controls. To identify an autoantigen a cDNA library from normal human choledochus was constructed and immunoscreened with patient sera. Using in vitro transcription and translation and immunoprecipitation we examined the immunoreactivity against PDZ domain containing 1 (PDZK1) in 35 patients with PSC, 198 control patients, and 94 healthy controls. RESULTS We observed a previously unpublished staining pattern in which cytoplasmatic granules and apical cell membranes of biliary epithelial cells were stained by PSC sera. Strong immunoreactivity to these structures was obtained with 12 out of 35 PSC sera (34%) but not with sera from healthy controls. By screening the cDNA library we identified PDZK1 as a candidate antigen. Immunoreactivity against PDZK1 was detected in 9% of PSC patients, 2% of inflammatory bowel disease (IBD) patients, 8% of autoimmune pancreatitis patients, 18% of Grave's disease patients, and 1% of healthy controls. CONCLUSIONS Previously unpublished, specific, and strong autoantibodies against epithelial cells of the bile duct in PSC sera were identified. Furthermore, PDZK1 is suggested as a potential new autoantigen.
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Affiliation(s)
- Brita Ardesjö
- Department of Medical Sciences University Hospital, Uppsala University, Uppsala, Sweden.
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Cano MM, Calonge ML, Ilundain AA. Expression of OCTN2 and OCTN3 in the apical membrane of rat renal cortex and medulla. J Cell Physiol 2010; 223:451-9. [PMID: 20112288 DOI: 10.1002/jcp.22054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Immunological assays and transport measurements in apical membrane vesicles revealed that the apical membrane of rat kidney cortex and medulla presents OCTN2 and OCTN3 proteins and transports L-[(3)H]-carnitine in a Na(+)-dependent and -independent manner. OCTN2 mediates the Na(+)/L-carnitine transport activity measured in medulla because (i) the transport showed the same characteristics as the cortical Na(+)/L-carnitine transporter and (ii) the medulla expressed OCTN2 mRNA and protein. The Na(+)-independent L-carnitine transport activity appears to be mediated by both OCTN2 and OCTN3 since: (i) Na(+)-independent L-carnitine uptake was inhibited by both, anti-OCTN2 and anti-OCTN3 antibodies, (ii) kinetics studies revealed the involvement of a high- and a low-affinity transport systems, and (iii) Western and immunohistochemistry studies revealed that OCTN3 protein is located at the apical membrane of the kidney epithelia. The Na(+)-independent L-carnitine uptake exhibited trans-stimulation by intravesicular L-carnitine or betaine. This trans-stimulation was inhibited by anti-OCTN3 antibody, but not by anti-OCTN2 antibody, indicating that OCTN3 can function as an L-carnitine/organic compound exchanger. This is the first report showing a functional apical OCTN2 in the renal medulla and a functional apical OCTN3 in both renal cortex and medulla.
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Affiliation(s)
- M M Cano
- Facultad de Farmacia, Departamento de Fisiología y Zoología (Biomembranes Group), Universidad de Sevilla, 41012Sevilla, Spain
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Kato S, Kato Y, Nakamura T, Sugiura T, Kubo Y, Deguchi Y, Tsuji A. Genetic deficiency of carnitine/organic cation transporter 2 (slc22a5) is associated with altered tissue distribution of its substrate pyrilamine in mice. Biopharm Drug Dispos 2010; 30:495-507. [PMID: 19821448 DOI: 10.1002/bdd.681] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Carnitine/organic cation transporter 2 (OCTN2) recognizes various cationic compounds as substrates in vitro, but information on its pharmacokinetic role in vivo is quite limited. This paper demonstrates altered tissue distribution of the OCTN2 substrate pyrilamine in juvenile visceral steatosis (jvs) mice, which have a hereditary defect of the octn2 gene. At 30 min after intravenous injection of pyrilamine, the tissue-to-plasma concentration ratio (K(p)) in the heart and pancreas was higher, whereas the K(p) in kidney and testis was lower in jvs mice compared with wild-type mice. Pyrilamine transport studies in isolated heart slices confirmed higher accumulation, together with lower efflux, of pyrilamine in the heart of jvs mice. The higher accumulation in heart slices of jvs mice was abolished by lowering the temperature, by increasing the substrate concentration, and in the presence of other H(1) antagonists or another OCTN2 substrate, carnitine, suggesting that OCTN2 extrudes pyrilamine from heart tissue. On the other hand, the lower distribution to the kidney of jvs mice was probably due to down-regulation of a basolateral transporter coupled with OCTN2, because, in jvs mice, (i) the K(p) of pyrilamine in kidney assessed immediately after intravenous injection (approximately 1 min) was also lower, (ii) the urinary excretion of pyrilamine was lower, and (iii) the uptake of pyrilamine in kidney slices was lower. The renal uptake of pyrilamine was saturable (K(m) approximately 236 microM) and was strongly inhibited by cyproheptadine, astemizole, ebastine and terfenadine. The present study thus indicates that genetic deficiency of octn2 alters pyrilamine disposition tissue-dependently.
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Affiliation(s)
- Sayaka Kato
- Division of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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Carnitine synthesis and uptake into cells are stimulated by fasting in pigs as a model of nonproliferating species. J Nutr Biochem 2009; 20:840-7. [DOI: 10.1016/j.jnutbio.2008.07.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 07/18/2008] [Accepted: 07/30/2008] [Indexed: 01/05/2023]
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Wen G, Ringseis R, Eder K. Mouse OCTN2 is directly regulated by peroxisome proliferator-activated receptor alpha (PPARalpha) via a PPRE located in the first intron. Biochem Pharmacol 2009; 79:768-76. [PMID: 19819229 DOI: 10.1016/j.bcp.2009.10.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 09/30/2009] [Accepted: 10/01/2009] [Indexed: 10/20/2022]
Abstract
Recent studies provided strong evidence to suggest that organic cation transporter 2 (OCTN2) is a direct target gene of peroxisome proliferator-activated receptor alpha (PPARalpha). However, subsequent studies failed to demonstrate a functional peroxisome proliferator response element (PPRE) in the promoter region of the OCTN2 gene. In the present study we hypothesized that the OCTN2 gene is transcriptionally induced by PPARalpha via a functional PPRE located in the first intron. In silico-analysis of the first intron of mouse OCTN2 revealed 11 putative PPRE with high similarity to the consensus PPRE. In addition, reporter gene assays using a mouse OCTN2 intron reporter construct containing a cluster of three partially overlapping PPRE (PPREint-1-8-10) revealed a marked response to exogenous mouse PPARalpha/RXRalpha and subsequent stimulation with PPARalpha agonist WY-14,643. Introduction of a selective mutation in either PPRE8 or PPRE10 in the PPREint-1-8-10 reporter constructs caused a substantial loss of the responsiveness to PPARalpha activation, but a selective mutation in PPRE1 resulted in a complete loss of responsiveness to PPARalpha activation. Moreover, gel shift assays revealed binding of PPARalpha/RXRalpha heterodimer to the PPRE1 of mouse OCTN2 first intron. In conclusion, the present study shows that mouse OCTN2 is a direct target gene of PPARalpha and that transcriptional upregulation of OCTN2 by PPARalpha is likely mediated via PPRE1 in its first intron.
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Affiliation(s)
- Gaiping Wen
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 2, 06120 Halle (Saale), Germany
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Kato Y, Miyazaki T, Kano T, Sugiura T, Kubo Y, Tsuji A. Involvement of influx and efflux transport systems in gastrointestinal absorption of celiprolol. J Pharm Sci 2009; 98:2529-39. [PMID: 19067419 DOI: 10.1002/jps.21618] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Gastrointestinal absorption of several beta-blockers is inhibited by citrus juices, although molecular mechanism(s) lying on their small intestinal absorption has not yet been identified. Here, we attempted to demonstrate involvement of both influx and efflux transporters in vivo in gastrointestinal absorption of celiprolol in mice. Plasma concentration of celiprolol (3 mg/kg) after oral administration was mostly under the limit of quantification in wild mice, whereas that in mdr1a/b knockout (mdr1a/b(-/-)) mice was much more obvious, indicating P-glycoprotein-mediated efflux. Then, the oral absorption of celiprolol in mdr1a/b(-/-) mice was further examined to investigate influx transport mechanism with avoiding effect of P-glycoprotein. Coadministration of bromosulfophthalein (BSP), an inhibitor of various influx transporters including organic anion transporting polypeptide (OATP) reduced plasma celiprolol concentration. Inhibition by BSP of celiprolol uptake from apical membranes was confirmed in Ussing-type chamber of small intestinal tissues. Uptake of celiprolol by human small intestinal transporter OATP-A/1A2 was also confirmed in Xenopus Laevis oocytes. Interestingly, OATP-A/1A2 accepts various beta-blockers including acebutolol, atenolol and sotalol, oral absorption of which is inhibited by coadministration of citrus juice or telithromycin in human. Taken together, these findings have suggested fundamental role of influx transport system(s) in oral absorption of celiprolol.
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Affiliation(s)
- Yukio Kato
- Division of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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