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Xiang J, Keep RF. Proton-Coupled Oligopeptide Transport (Slc15) in the Brain: Past and Future Research. Pharm Res 2023; 40:2533-2540. [PMID: 37308743 DOI: 10.1007/s11095-023-03550-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 06/06/2023] [Indexed: 06/14/2023]
Abstract
This mini-review describes the role of the solute carrier (SLC)15 family of proton-coupled oligopeptide transporters (POTs) and particularly Pept2 (Slc15A2) and PhT1 (Slc15A4) in the brain. That family transports endogenous di- and tripeptides and peptidomimetics but also a number of drugs. The review focuses on the pioneering work of David E. Smith in the field in identifying the impact of PepT2 at the choroid plexus (the blood-CSF barrier) as well as PepT2 and PhT1 in brain parenchymal cells. It also discusses recent findings and future directions in relation to brain POTs including cellular and subcellular localization, regulatory pathways, transporter structure, species differences and disease states.
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Affiliation(s)
- Jianming Xiang
- Department of Neurosurgery, University of Michigan, R5018 BSRB 109 Zina Pitcher Place, Ann Arbor, MI, 48109, USA
| | - Richard F Keep
- Department of Neurosurgery, University of Michigan, R5018 BSRB 109 Zina Pitcher Place, Ann Arbor, MI, 48109, USA.
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Wang C, Chu C, Ji X, Luo G, Xu C, He H, Yao J, Wu J, Hu J, Jin Y. Biology of Peptide Transporter 2 in Mammals: New Insights into Its Function, Structure and Regulation. Cells 2022; 11:cells11182874. [PMID: 36139448 PMCID: PMC9497230 DOI: 10.3390/cells11182874] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/09/2022] [Accepted: 09/12/2022] [Indexed: 11/16/2022] Open
Abstract
Peptide transporter 2 (PepT2) in mammals plays essential roles in the reabsorption and conservation of peptide-bound amino acids in the kidney and in maintaining neuropeptide homeostasis in the brain. It is also of significant medical and pharmacological significance in the absorption and disposing of peptide-like drugs, including angiotensin-converting enzyme inhibitors, β-lactam antibiotics and antiviral prodrugs. Understanding the structure, function and regulation of PepT2 is of emerging interest in nutrition, medical and pharmacological research. In this review, we provide a comprehensive overview of the structure, substrate preferences and localization of PepT2 in mammals. As PepT2 is expressed in various organs, its function in the liver, kidney, brain, heart, lung and mammary gland has also been addressed. Finally, the regulatory factors that affect the expression and function of PepT2, such as transcriptional activation and posttranslational modification, are also discussed.
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Affiliation(s)
- Caihong Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, China
- Department of Bioinformatics, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
- Zhejiang Conba Pharmaceutical Limited Company, Hangzhou 310052, China
| | - Chu Chu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, China
| | - Xiang Ji
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, China
| | - Guoliang Luo
- Zhejiang Conba Pharmaceutical Limited Company, Hangzhou 310052, China
- Zhejiang Institute of Modern Chinese Medicine and Natural Medicine, Hangzhou 310052, China
| | - Chunling Xu
- Zhejiang Conba Pharmaceutical Limited Company, Hangzhou 310052, China
- Zhejiang Institute of Modern Chinese Medicine and Natural Medicine, Hangzhou 310052, China
| | - Houhong He
- Zhejiang Conba Pharmaceutical Limited Company, Hangzhou 310052, China
- Zhejiang Institute of Modern Chinese Medicine and Natural Medicine, Hangzhou 310052, China
| | - Jianbiao Yao
- Zhejiang Conba Pharmaceutical Limited Company, Hangzhou 310052, China
- Zhejiang Institute of Modern Chinese Medicine and Natural Medicine, Hangzhou 310052, China
| | - Jian Wu
- Zhejiang Conba Pharmaceutical Limited Company, Hangzhou 310052, China
- Zhejiang Institute of Modern Chinese Medicine and Natural Medicine, Hangzhou 310052, China
| | - Jiangning Hu
- Zhejiang Conba Pharmaceutical Limited Company, Hangzhou 310052, China
- Zhejiang Institute of Modern Chinese Medicine and Natural Medicine, Hangzhou 310052, China
- Correspondence: (J.H.); (Y.J.)
| | - Yuanxiang Jin
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310032, China
- Correspondence: (J.H.); (Y.J.)
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Hu T, Zha W, Sun A, Wang J. Live Tissue Imaging Reveals Distinct Transcellular Pathways for Organic Cations and Anions at the Blood-Cerebrospinal Fluid Barrier. Mol Pharmacol 2022; 101:334-342. [PMID: 35193935 PMCID: PMC9092482 DOI: 10.1124/molpharm.121.000439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 01/31/2022] [Indexed: 11/22/2022] Open
Abstract
Formed by the choroid plexus epithelial (CPE) cells, the blood-cerebrospinal fluid barrier (BCSFB) plays an active role in removing drugs, toxins, and metabolic wastes from the brain. Several organic cation and anion transporters are expressed in the CPE cells, but how they functionally mediate transepithelial transport of organic cations and anions remain unclear. In this study, we visualized the transcellular transport of fluorescent organic cation and organic anion probes using live tissue imaging in freshly isolated mouse choroid plexuses (CPs). The cationic probe, 4-[4-(dimethylamino)phenyl]-1-methylpyridinium iodide (IDT307) was transported into CPE cells at the apical membrane and highly accumulated in mitochondria. Consistent with the lack of expression of organic cation efflux transporters, there was little efflux of IDT307 into the blood capillary space. Furthermore, IDT307 uptake and intracellular accumulation was attenuated by approximately 70% in CP tissues from mice with targeted deletion of the plasma membrane monoamine transporter (Pmat). In contrast, the anionic probe fluorescein-methotrexate (FL-MTX) was rapidly transported across the CPE cells into the capillary space with little intracellular accumulation. Rifampicin, an inhibitor of organic anion transporting polypeptides (OATPs), completely blocked FL-MTX uptake into the CPE cells whereas MK-571, a pan-inhibitor of multidrug resistance associated proteins (MRPs), abolished basolateral efflux of FL-MTX. In summary, our results suggest distinct transcellular transport pathways for organic cations and anions at the BCSFB and reveal a pivotal role of PMAT, OATP and MRP transporters in organic cation and anion transport at the blood-cerebrospinal fluid interface. SIGNIFICANCE STATEMENT: Live tissue imaging revealed that while organic cations are transported from the cerebrospinal fluid (CSF) into the choroid plexus epithelial cells by plasma membrane monoamine transporter without efflux into the blood, amphipathic anions in the CSF are efficiently transported across the BCSFB through the collaborated function of apical organic anion transporting polypeptides and basolateral multidrug resistance associated proteins. These findings contribute to a mechanistic understanding of the molecular and cellular pathways for choroid plexus clearance of solutes from the brain.
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Affiliation(s)
- Tao Hu
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Weibin Zha
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Austin Sun
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Joanne Wang
- Department of Pharmaceutics, University of Washington, Seattle, Washington
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Kratzer I, Ek J, Stolp H. The molecular anatomy and functions of the choroid plexus in healthy and diseased brain. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183430. [PMID: 32750317 DOI: 10.1016/j.bbamem.2020.183430] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 07/18/2020] [Accepted: 07/20/2020] [Indexed: 01/16/2023]
Abstract
The choroid plexus (CP) is located in the ventricular system of the brain (one in each ventricle), and the CP epithelial cells form an important barrier between the blood and the cerebrospinal fluid (CSF). Their main function comprises CSF secretion, maintenance of brain homeostasis, signalling, and forming a neuroprotective barrier against harmful external and internal compounds. The CPs mature early and demonstrate expressional changes of barrier-specific genes and proteins related to location and developmental stage of the CP. Important proteins for the barrier function include tight junction proteins, numerous transporters and enzymes. Natural senescence leads to structural changes in the CP cells and reduced or loss of function, while further loss of CP function and changes in immune status may be relevant in neurodegenerative diseases such as Alzheimer's disease and Multiple Sclerosis. Neuroprotective genes expressed at CPs may be unexplored targets for new therapies for neurodegenerative diseases.
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Affiliation(s)
- Ingrid Kratzer
- FLUID Team, Lyon Neurosciences Research Center, INSERM U1028 CNRS UMR 5292, University Claude Bernard Lyon 1, 69008 Lyon, France; Friedensgasse 3, 8010 Graz, Austria.
| | - Joakim Ek
- Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, Medicinaregatan 11, Box 432, 40530 Göteborg, Sweden.
| | - Helen Stolp
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London NW0 1TU, UK.
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6
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Liu L, Liu X. Contributions of Drug Transporters to Blood-Brain Barriers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1141:407-466. [PMID: 31571171 DOI: 10.1007/978-981-13-7647-4_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Blood-brain interfaces comprise the cerebral microvessel endothelium forming the blood-brain barrier (BBB) and the epithelium of the choroid plexuses forming the blood-cerebrospinal fluid barrier (BCSFB). Their main functions are to impede free diffusion between brain fluids and blood; to provide transport processes for essential nutrients, ions, and metabolic waste products; and to regulate the homeostasis of central nervous system (CNS), all of which are attributed to absent fenestrations, high expression of tight junction proteins at cell-cell contacts, and expression of multiple transporters, receptors, and enzymes. Existence of BBB is an important reason that systemic drug administration is not suitable for the treatment of CNS diseases. Some diseases, such epilepsy, Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and diabetes, alter BBB function via affecting tight junction proteins or altering expression and function of these transporters. This chapter will illustrate function of BBB, expression of transporters, as well as their alterations under disease status.
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Affiliation(s)
- Li Liu
- China Pharmaceutical University, Nanjing, China
| | - Xiaodong Liu
- China Pharmaceutical University, Nanjing, China.
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Wang Q, Zuo Z. Impact of transporters and enzymes from blood–cerebrospinal fluid barrier and brain parenchyma on CNS drug uptake. Expert Opin Drug Metab Toxicol 2018; 14:961-972. [DOI: 10.1080/17425255.2018.1513493] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Qianwen Wang
- School of Pharmacy, The Chinese University of Hong Kong, Hong Kong, P. R. China
| | - Zhong Zuo
- School of Pharmacy, The Chinese University of Hong Kong, Hong Kong, P. R. China
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8
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Ghersi-Egea JF, Strazielle N, Catala M, Silva-Vargas V, Doetsch F, Engelhardt B. Molecular anatomy and functions of the choroidal blood-cerebrospinal fluid barrier in health and disease. Acta Neuropathol 2018; 135:337-361. [PMID: 29368213 DOI: 10.1007/s00401-018-1807-1] [Citation(s) in RCA: 240] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/07/2018] [Accepted: 01/13/2018] [Indexed: 02/07/2023]
Abstract
The barrier between the blood and the ventricular cerebrospinal fluid (CSF) is located at the choroid plexuses. At the interface between two circulating fluids, these richly vascularized veil-like structures display a peculiar morphology explained by their developmental origin, and fulfill several functions essential for CNS homeostasis. They form a neuroprotective barrier preventing the accumulation of noxious compounds into the CSF and brain, and secrete CSF, which participates in the maintenance of a stable CNS internal environment. The CSF circulation plays an important role in volume transmission within the developing and adult brain, and CSF compartments are key to the immune surveillance of the CNS. In these contexts, the choroid plexuses are an important source of biologically active molecules involved in brain development, stem cell proliferation and differentiation, and brain repair. By sensing both physiological changes in brain homeostasis and peripheral or central insults such as inflammation, they also act as sentinels for the CNS. Finally, their role in the control of immune cell traffic between the blood and the CSF confers on the choroid plexuses a function in neuroimmune regulation and implicates them in neuroinflammation. The choroid plexuses, therefore, deserve more attention while investigating the pathophysiology of CNS diseases and related comorbidities.
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Affiliation(s)
- Jean-François Ghersi-Egea
- Fluid Team, Lyon Neurosciences Research Center, INSERM U1028, CNRS, UMR5292, University Lyon-1, Lyon, France.
| | - Nathalie Strazielle
- Fluid Team, Lyon Neurosciences Research Center, INSERM U1028, CNRS, UMR5292, University Lyon-1, Lyon, France
- Brain-i, Lyon, France
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9
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Uchida Y, Zhang Z, Tachikawa M, Terasaki T. Quantitative targeted absolute proteomics of rat blood-cerebrospinal fluid barrier transporters: comparison with a human specimen. J Neurochem 2015; 134:1104-15. [DOI: 10.1111/jnc.13147] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 04/09/2015] [Accepted: 04/13/2015] [Indexed: 12/16/2022]
Affiliation(s)
- Yasuo Uchida
- Graduate School of Pharmaceutical Sciences; Tohoku University; Sendai Japan
| | - Zhengyu Zhang
- Graduate School of Pharmaceutical Sciences; Tohoku University; Sendai Japan
| | - Masanori Tachikawa
- Graduate School of Pharmaceutical Sciences; Tohoku University; Sendai Japan
| | - Tetsuya Terasaki
- Graduate School of Pharmaceutical Sciences; Tohoku University; Sendai Japan
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Chodobski A, Ghersi-Egea JF, Nicholson C, Nagaraja TN, Szmydynger-Chodobska J. The quest for a better insight into physiology of fluids and barriers of the brain: the exemplary career of Joseph D. Fenstermacher. Fluids Barriers CNS 2015; 12:1. [PMID: 25745556 PMCID: PMC4350980 DOI: 10.1186/2045-8118-12-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 12/18/2014] [Indexed: 12/27/2022] Open
Abstract
In June 2014 Dr. Joseph D. Fenstermacher celebrated his 80th birthday, which was honored by the symposium held in New London, NH, USA. This review discusses Fenstermacher's contribution to the field of fluids and barriers of the CNS. Specifically, his fundamental work on diffusion of molecules within the brain extracellular space and the research on properties of the blood-brain barrier in health and disease are described. Fenstermacher's early research on cerebrospinal fluid dynamics and the regulation of cerebral blood flow is also reviewed, followed by the discussion of his more recent work involving the use of magnetic resonance imaging.
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Affiliation(s)
- Adam Chodobski
- Department of Emergency Medicine, Neurotrauma and Brain Barriers Research Laboratory, The Warren Alpert Medical School of Brown University, Coro Center West, Room 112, 1 Hoppin Street, Providence, RI 02903 USA
| | - Jean-François Ghersi-Egea
- Blood-Brain Interface Group, Oncoflam Team and BIP Platform INSERM U 1028, CNRS UMR5292 Lyon Neuroscience Research Center, Faculté de Médecine RTH Laennec, Rue Guillaume Paradin, Cedex 08, 69372 Lyon, France
| | - Charles Nicholson
- Department of Neuroscience and Physiology, NYU School of Medicine, MSB 460, 550 First Avenue, New York, NY 10016 USA
| | - Tavarekere N Nagaraja
- Department of Anesthesiology, Henry Ford Hospital, 2799 West Grand Blvd., Detroit, MI 48202-2689 USA
| | - Joanna Szmydynger-Chodobska
- Department of Emergency Medicine, Neurotrauma and Brain Barriers Research Laboratory, The Warren Alpert Medical School of Brown University, Coro Center West, Room 112, 1 Hoppin Street, Providence, RI 02903 USA
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11
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Hu Y, Xie Y, Keep RF, Smith DE. Divergent developmental expression and function of the proton-coupled oligopeptide transporters PepT2 and PhT1 in regional brain slices of mouse and rat. J Neurochem 2014; 129:955-65. [PMID: 24548120 DOI: 10.1111/jnc.12687] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/26/2014] [Accepted: 02/13/2014] [Indexed: 01/22/2023]
Abstract
This study evaluated the developmental gene and protein expression of proton-coupled oligopeptide transporters (POTs: peptide transporter, PepT1 and PepT2; peptide-histidine transporter, PhT1 and PhT2) in different regions of rodent brain, and the age-dependent uptake of a POT substrate, glycylsarcosine (GlySar), in brain slices. Slices were obtained from cerebral cortex, cerebellum and hippocampus of wildtype and PepT2 null mice, and from rats at different ages. Gene and protein expression were determined by real-time PCR and immunoblot analyses. Brain slice uptakes of radiolabeled glycylsarcosine were determined in the absence and presence of excess unlabeled glycylsarcosine or l-histidine, the latter being an inhibitor of PhT1/2 but not PepT1/2. As PepT2 and PhT1 transcripts were abundantly expressed in all three regions of mouse brain, little to no expression was observed for PepT1 and PhT2. PhT1 protein was present in brain regions of adult but not neonatal mice and expression levels increased with age in rats. Glycylsarcosine uptake, inhibition and transporter dominance did not show regional brain or species differences. However, there were clear age-related differences in functional activity, with PepT2 dominating in neonatal mice and rats, and PhT1 dominating in adult rodents. These developmental changes may markedly impact the neural activity of both endogenous and exogenous (drug) peptides/mimetics. Developmental gene and protein expression of peptide transporters was evaluated in various regions of rodent brain, along with age-dependent uptake of dipeptide. We found marked changes in protein expression and functional activity of PhT1 and PepT2, the former predominating in adult and the latter in neonate. These developmental changes may markedly impact the neural activity of endogenous and exogenous peptides/mimetics.
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Affiliation(s)
- Yongjun Hu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI, USA
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12
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Tachikawa M, Uchida Y, Ohtsuki S, Terasaki T. Recent Progress in Blood–Brain Barrier and Blood–CSF Barrier Transport Research: Pharmaceutical Relevance for Drug Delivery to the Brain. DRUG DELIVERY TO THE BRAIN 2014. [DOI: 10.1007/978-1-4614-9105-7_2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Functional Expression of Drug Transporters in Glial Cells. PHARMACOLOGY OF THE BLOOD BRAIN BARRIER: TARGETING CNS DISORDERS 2014; 71:45-111. [DOI: 10.1016/bs.apha.2014.06.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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14
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Smith DE, Clémençon B, Hediger MA. Proton-coupled oligopeptide transporter family SLC15: physiological, pharmacological and pathological implications. Mol Aspects Med 2013; 34:323-36. [PMID: 23506874 DOI: 10.1016/j.mam.2012.11.003] [Citation(s) in RCA: 218] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 06/22/2012] [Indexed: 01/04/2023]
Abstract
Mammalian members of the proton-coupled oligopeptide transporter family (SLC15) are integral membrane proteins that mediate the cellular uptake of di/tripeptides and peptide-like drugs. The driving force for uphill electrogenic symport is the chemical gradient and membrane potential which favors proton uptake into the cell along with the peptide/mimetic substrate. The peptide transporters are responsible for the absorption and conservation of dietary protein digestion products in the intestine and kidney, respectively, and in maintaining homeostasis of neuropeptides in the brain. They are also responsible for the absorption and disposition of a number of pharmacologically important compounds including some aminocephalosporins, angiotensin-converting enzyme inhibitors, antiviral prodrugs, and others. In this review, we provide updated information on the structure-function of PepT1 (SLC15A1), PepT2 (SLC15A2), PhT1 (SLC15A4) and PhT2 (SLC15A3), and their expression and localization in key tissues. Moreover, mammalian peptide transporters are discussed in regard to pharmacogenomic and regulatory implications on host pharmacology and disease, and as potential targets for drug delivery. Significant emphasis is placed on the evolving role of these peptide transporters as elucidated by studies using genetically modified animals. Whenever possible, the relevance of drug-drug interactions and regulatory mechanisms are evaluated using in vivo studies.
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Affiliation(s)
- David E Smith
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
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15
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Kratzer I, Liddelow SA, Saunders NR, Dziegielewska KM, Strazielle N, Ghersi-Egea JF. Developmental changes in the transcriptome of the rat choroid plexus in relation to neuroprotection. Fluids Barriers CNS 2013; 10:25. [PMID: 23915922 PMCID: PMC3737068 DOI: 10.1186/2045-8118-10-25] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 07/10/2013] [Indexed: 11/10/2022] Open
Abstract
Background The choroid plexuses are the interface between the blood and the cerebrospinal fluid (CSF) contained within the ventricular spaces of the central nervous system. The tight junctions linking adjacent cells of the choroidal epithelium create a physical barrier to paracellular movement of molecules. Multispecific efflux transporters as well as drug-metabolizing and antioxidant enzymes functioning in these cells contribute to a metabolic barrier. These barrier properties reflect a neuroprotective function of the choroid plexus. The choroid plexuses develop early during embryogenesis and provide pivotal control of the internal environment throughout development when the brain is especially vulnerable to toxic insults. Perinatal injuries like hypoxia and trauma, and exposure to drugs or toxic xenobiotics can have serious consequences on neurogenesis and long-term development. The present study describes the developmental expression pattern of genes involved in the neuroprotective functions of the blood–CSF barrier. Methods The transcriptome of rat lateral ventricular choroid plexuses isolated from fifteen-day-old embryos, nineteen-day old fetuses, two-day old pups, and adults was analyzed by a combination of Affymetrix microarrays, Illumina RNA-Sequencing, and quantitative RT-PCR. Results Genes coding for proteins involved in junction formation are expressed early during development. Overall perinatal expression levels of genes involved in drug metabolism and antioxidant mechanisms are similar to, or higher than levels measured in adults. A similar developmental pattern was observed for multispecific efflux transporter genes of the Abc and Slc superfamilies. Expression of all these genes was more variable in choroid plexus from fifteen-day-old embryos. A large panel of transcription factors involved in the xenobiotic- or cell stress-mediated induction of detoxifying enzymes and transporters is also expressed throughout development. Conclusions This transcriptomic analysis suggests relatively well–established neuroprotective mechanisms at the blood-CSF barrier throughout development of the rat. The expression of many transcription factors early in development raises the possibility of additional protection for the vulnerable developing brain, should the fetus or newborn be exposed to drugs or other xenobiotics.
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Affiliation(s)
- Ingrid Kratzer
- Inserm U1028, Lyon Neuroscience Research Center, Neurooncology & Neuroinflammation Team, Lyon-1 University, Lyon F-69000, France.
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In vitro, in vivo and in silico models of drug distribution into the brain. J Pharmacokinet Pharmacodyn 2013; 40:301-14. [DOI: 10.1007/s10928-013-9303-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Accepted: 01/31/2013] [Indexed: 10/27/2022]
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Strazielle N, Ghersi-Egea JF. Physiology of blood-brain interfaces in relation to brain disposition of small compounds and macromolecules. Mol Pharm 2013; 10:1473-91. [PMID: 23298398 DOI: 10.1021/mp300518e] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The brain develops and functions within a strictly controlled environment resulting from the coordinated action of different cellular interfaces located between the blood and the extracellular fluids of the brain, which include the interstitial fluid and the cerebrospinal fluid (CSF). As a correlate, the delivery of pharmacologically active molecules and especially macromolecules to the brain is challenged by the barrier properties of these interfaces. Blood-brain interfaces comprise both the blood-brain barrier located at the endothelium of the brain microvessels and the blood-CSF barrier located at the epithelium of the choroid plexuses. Although both barriers develop extensive surface areas of exchange between the blood and the neuropil or the CSF, the molecular fluxes across these interfaces are tightly regulated. Cerebral microvessels acquire a barrier phenotype early during cerebral vasculogenesis under the influence of the Wnt/β-catenin pathway, and of recruited pericytes. Later in development, astrocytes also play a role in blood-brain barrier maintenance. The tight choroid plexus epithelium develops very early during embryogenesis. It is specified by various signaling molecules from the embryonic dorsal midline, such as bone morphogenic proteins, and grows under the influence of Sonic hedgehog protein. Tight junctions at each barrier comprise a distinctive set of claudins from the pore-forming and tightening categories that determine their respective paracellular barrier characteristics. Vesicular traffic is limited in the cerebral endothelium and abundant in the choroidal epithelium, yet without evidence of active fluid phase transcytosis. Inorganic ion transport is highly regulated across the barriers. Small organic compounds such as nutrients, micronutrients and hormones are transported into the brain by specific solute carriers. Other bioactive metabolites, lipophilic toxic xenobiotics or pharmacological agents are restrained from accumulating in the brain by several ATP-binding cassette efflux transporters, multispecific solute carriers, and detoxifying enzymes. These various molecular effectors differently distribute between the two barriers. Receptor-mediated endocytotic and transcytotic mechanisms are active in the barriers. They enable brain penetration of selected polypeptides and proteins, or inversely macromolecule efflux as it is the case for immnoglobulins G. An additional mechanism specific to the BCSFB mediates the transport of selected plasma proteins from blood into CSF in the developing brain. All these mechanisms could be explored and manipulated to improve macromolecule delivery to the brain.
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Affiliation(s)
- N Strazielle
- Brain-i, Lyon Neuroscience Research Center, Lyon, France.
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Ashraf T, Kis O, Banerjee N, Bendayan R. Drug Transporters At Brain Barriers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013. [DOI: 10.1007/978-1-4614-4711-5_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Duan H, Wang J. Impaired monoamine and organic cation uptake in choroid plexus in mice with targeted disruption of the plasma membrane monoamine transporter (Slc29a4) gene. J Biol Chem 2012; 288:3535-44. [PMID: 23255610 DOI: 10.1074/jbc.m112.436972] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The choroid plexus (CP) forms the blood-cerebrospinal fluid (CSF) barrier and protects the brain from circulating metabolites, drugs, and toxins. The plasma membrane monoamine transporter (PMAT, SLC29A4) is a new polyspecific organic cation transporter that transports a wide variety of organic cations including biogenic amines, cationic drugs, and neurotoxins. PMAT is known to be expressed in the CP, but its specific role in CP transport of organic cations has not been clearly defined. Here we showed that PMAT transcript is highly expressed in human and mouse CPs, whereas transcripts of other functionally related transporters are minimally expressed in the CPs. Immunofluorescence staining further revealed that PMAT protein is localized to the apical (CSF-facing) membrane of the CP epithelium, consistent with a role of transporting organic cations from the CSF into CP epithelial cells. To further evaluate the role of PMAT in the CP, mice with targeted deletion of the Slc29a4 gene were generated and validated. Although Pmat(-/-) mice showed no overt abnormalities, the uptake of monoamines and the neurotoxin 1-methyl-4-phenylpyridinium was significantly reduced in CP tissues isolated from the knock-out mice. Together, our data demonstrated that PMAT is a major transporter for CP uptake of bioactive amines and xenobiotic cations. By removing its substrates from the CSF, PMAT may play an important role in protecting the brain from cationic neurotoxins and other potentially toxic organic cations.
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Affiliation(s)
- Haichuan Duan
- Department of Pharmaceutics, University of Washington, Seattle, Washington 98195, USA
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Ho HTB, Dahlin A, Wang J. Expression Profiling of Solute Carrier Gene Families at the Blood-CSF Barrier. Front Pharmacol 2012; 3:154. [PMID: 22936914 PMCID: PMC3426838 DOI: 10.3389/fphar.2012.00154] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/01/2012] [Indexed: 12/12/2022] Open
Abstract
The choroid plexus (CP) is a highly vascularized tissue in the brain ventricles and acts as the blood-cerebrospinal fluid (CSF) barrier (BCSFB). A main function of the CP is to secrete CSF, which is accomplished by active transport of small ions and water from the blood side to the CSF side. The CP also supplies the brain with certain nutrients, hormones, and metal ions, while removing metabolites and xenobiotics from the CSF. Numerous membrane transporters are expressed in the CP in order to facilitate the solute exchange between the blood and the CSF. The solute carrier (SLC) superfamily represents a major class of transporters in the CP that constitutes the molecular mechanisms for CP function. Recently, we systematically and quantitatively examined Slc gene expression in 20 anatomically comprehensive brain areas in the adult mouse brain using high-quality in situ hybridization data generated by the Allen Brain Atlas. Here we focus our analysis on Slc gene expression at the BCSFB using previously obtained data. Of the 252 Slc genes present in the mouse brain, 202 Slc genes were found at detectable levels in the CP. Unsupervised hierarchical cluster analysis showed that the CP Slc gene expression pattern is substantially different from the other 19 analyzed brain regions. The majority of the Slc genes in the CP are expressed at low to moderate levels, whereas 28 Slc genes are present in the CP at the highest levels. These highly expressed Slc genes encode transporters involved in CSF secretion, energy production, and transport of nutrients, hormones, neurotransmitters, sulfate, and metal ions. In this review, the functional characteristics and potential importance of these Slc transporters in the CP are discussed, with particular emphasis on their localization and physiological functions at the BCSFB.
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Affiliation(s)
- Horace T B Ho
- Department of Pharmaceutics, University of Washington Seattle, WA, USA
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Li J, Akagi K, Hu Y, Trivett AL, Hlynialuk CJ, Swing DA, Volfovsky N, Morgan TC, Golubeva Y, Stephens RM, Smith DE, Symer DE. Mouse endogenous retroviruses can trigger premature transcriptional termination at a distance. Genome Res 2012; 22:870-84. [PMID: 22367191 PMCID: PMC3337433 DOI: 10.1101/gr.130740.111] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 02/09/2012] [Indexed: 01/15/2023]
Abstract
Endogenous retrotransposons have caused extensive genomic variation within mammalian species, but the functional implications of such mobilization are mostly unknown. We mapped thousands of endogenous retrovirus (ERV) germline integrants in highly divergent, previously unsequenced mouse lineages, facilitating a comparison of gene expression in the presence or absence of local insertions. Polymorphic ERVs occur relatively infrequently in gene introns and are particularly depleted from genes involved in embryogenesis or that are highly expressed in embryonic stem cells. Their genomic distribution implies ongoing negative selection due to deleterious effects on gene expression and function. A polymorphic, intronic ERV at Slc15a2 triggers up to 49-fold increases in premature transcriptional termination and up to 39-fold reductions in full-length transcripts in adult mouse tissues, thereby disrupting protein expression and functional activity. Prematurely truncated transcripts also occur at Polr1a, Spon1, and up to ∼5% of other genes when intronic ERV polymorphisms are present. Analysis of expression quantitative trait loci (eQTLs) in recombinant BxD mouse strains demonstrated very strong genetic associations between the polymorphic ERV in cis and disrupted transcript levels. Premature polyadenylation is triggered at genomic distances up to >12.5 kb upstream of the ERV, both in cis and between alleles. The parent of origin of the ERV is associated with variable expression of nonterminated transcripts and differential DNA methylation at its 5'-long terminal repeat. This study defines an unexpectedly strong functional impact of ERVs in disrupting gene transcription at a distance and demonstrates that ongoing retrotransposition can contribute significantly to natural phenotypic diversity.
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Affiliation(s)
- Jingfeng Li
- Human Cancer Genetics Program and Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio 43210, USA
| | - Keiko Akagi
- Human Cancer Genetics Program and Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio 43210, USA
| | - Yongjun Hu
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | - Christopher J.W. Hlynialuk
- Human Cancer Genetics Program and Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio 43210, USA
| | - Deborah A. Swing
- Mouse Cancer Genetics Program, National Cancer Institute, Frederick, Maryland 21702, USA
| | - Natalia Volfovsky
- Advanced Biomedical Computing Center, Information Systems Program and
| | - Tamara C. Morgan
- Histotechnology Laboratory, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland 21702, USA
| | - Yelena Golubeva
- Histotechnology Laboratory, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland 21702, USA
| | | | - David E. Smith
- Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - David E. Symer
- Human Cancer Genetics Program and Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio 43210, USA
- Department of Internal Medicine and Department of Biomedical Informatics, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio 43210, USA
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Keep RF, Smith DE. Choroid plexus transport: gene deletion studies. Fluids Barriers CNS 2011; 8:26. [PMID: 22053861 PMCID: PMC3231976 DOI: 10.1186/2045-8118-8-26] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 11/04/2011] [Indexed: 11/26/2022] Open
Abstract
This review examines the use of transporter knockout (KO) animals to evaluate transporter function at the choroid plexus (the blood-CSF barrier; BCSFB). Compared to the blood-brain barrier, there have been few such studies on choroid plexus (CP) function. These have primarily focused on Pept2 (an oligopeptide transporter), ATP-binding cassette (ABC) transporters, Oat3 (an organic anion transporter), Svct2 (an ascorbic acid transporter), transthyretin, ion transporters, and ion and water channels. This review focuses on the knowledge gained from such studies, both with respect to specific transporters and in general to the role of the CP and its impact on brain parenchyma. It also discusses the pros and cons of using KO animals in such studies and the technical approaches that can be used.
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Affiliation(s)
- Richard F Keep
- Department of Neurosurgery, R5018 BSRB, University of Michigan, Ann Arbor, Michigan 48109-2200, USA.
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