Characterization and tissue localization of zebrafish homologs of the human ABCB1 multidrug transporter

AbstractCapillary endothelial cells of the human blood–brain barrier (BBB) express high levels of P-glycoprotein (P-gp, encoded by ABCB1) and ABCG2 (encoded by ABCG2). However, little information is available regarding ATP-binding cassette transporters expressed at the zebrafish BBB, which has emerged as a potential model system. We report the characterization and tissue localization of two genes that are similar to ABCB1, zebrafish abcb4 and abcb5. When stably expressed in HEK293 cells, both Abcb4 and Abcb5 conferred resistance to P-gp substrates; however, Abcb5 poorly transported doxorubicin and mitoxantrone compared to zebrafish Abcb4. Additionally, Abcb5 did not transport the fluorescent P-gp probes BODIPY-ethylenediamine or LDS 751, while they were transported by Abcb4. High-throughput screening of 90 human P-gp substrates confirmed that Abcb4 has an overlapping substrate specificity profile with P-gp. In the brain vasculature, RNAscope probes for abcb4 colocalized with staining by the P-gp antibody C219, while abcb5 was not detected. The abcb4 probe also colocalized with claudin-5 in brain endothelial cells. Abcb4 and Abcb5 had different tissue localizations in multiple zebrafish tissues, potentially indicating different functions. The data suggest that zebrafish Abcb4 functionally phenocopies P-gp and that the zebrafish may serve as a model to study the role of P-gp at the BBB.

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Characterization and tissue localization of zebrafish homologs of the human ABCB1 multidrug transporter

10.1101/2021.02.18.431829 ◽

2021 ◽

Author(s):

Robert W. Robey ◽

Andrea N. Robinson ◽

Fatima Ali-Rahmani ◽

Lyn M. Huff ◽

Sabrina Lusvarghi ◽

...

Keyword(s):

Endothelial Cells ◽

Multidrug Transporter ◽

Glycoprotein P ◽

Tissue Localization ◽

Brain Vasculature ◽

P Glycoprotein ◽

Capillary Endothelial Cells ◽

The Brain ◽

Viable Model

ABSTRACTGiven its similarities with mammalian systems, the zebrafish has emerged as a potential model to study the blood-brain barrier (BBB). Capillary endothelial cells at the human BBB express high levels of P-glycoprotein (P-gp, encoded by the ABCB1 gene) and ABCG2 (encoded by the ABCG2 gene). However, little information has been available about ATP-binding cassette transporters expressed at the zebrafish BBB. In this study, we focus on the characterization and tissue localization of two genes that are similar to human ABCB1, zebrafish abcb4 and abcb5. Cytotoxicity assays with stably-transfected cell lines revealed that zebrafish Abcb5 cannot efficiently transport the substrates doxorubicin and mitoxantrone compared to human P-gp and zebrafish Abcb4. Additionally, zebrafish Abcb5 did not transport the fluorescent probes BODIPY-ethylenediamine or LDS 751, while they were readily transported by Abcb4 and P-gp. A high-throughput screen conducted with 90 human P-gp substrates confirmed that zebrafish Abcb4 has overlapping substrate specificity with P-gp. Basal ATPase activity of zebrafish Abcb4 and Abcb5 was comparable to that of human P-gp. In the brain vasculature, RNAscope probes to detect abcb4 colocalized with staining by the P-gp antibody C219, while abcb5 was not detected. Zebrafish abcb4 also colocalized with claudin-5 expression in brain endothelial cells. Abcb4 and Abcb5 had different tissue localizations in multiple zebrafish tissues, consistent with different functions. The data suggest that zebrafish Abcb4 most closely phenocopies P-gp and that the zebrafish may be a viable model to study the role of the multidrug transporter P-gp at the BBB.

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Abstract TP276: Perlecan Is Required for the Maintenance of the Blood-Brain Barrier through the Interaction with Pericytes in a Mouse Ischemic Stroke Model

Stroke ◽

10.1161/str.48.suppl_1.tp276 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Kuniyuki Nakamura ◽

Tomoko Ikeuchi ◽

Peipei Zhang ◽

Craig Rhodes ◽

Yuta Chiba ◽

...

Keyword(s):

Endothelial Cells ◽

Ischemic Stroke ◽

Endothelial Cell ◽

Blood Brain Barrier ◽

Repair Process ◽

Ischemic Lesion ◽

Brain Vasculature ◽

Integrin Α5 ◽

The Brain

Introduction: The disruption of the blood-brain barrier (BBB) is a contributing factor for the deterioration of brain damages in ischemic stroke. Recent studies revealed that microvascular pericytes are involved in the maintenance of the BBB and in the repair process through platelet-derived growth factor receptor β (PDGFRβ), the expression of which is increased around the ischemic lesion. Here we focus on perlecan, the major heparan sulfate proteoglycan in the basement membrane (BM). It is expressed by endothelial cells in the brain and is implicated in many biological functions. In this report, we have studied the role of Perlecan in the BBB breakdown and in the subsequent repair process after ischemic stroke in a mouse model. We hypothesized that perlecan may play a protective role in the disruption of BBB through the interaction with pericytes after ischemic stroke. Methods: To elucidate the role of perlecan in the brain vasculature, we induced a 60-minute transient middle cerebral artery occlusion (MCAO) in adult conditional perlecan -deficient ( Perlecan -/- -Tg) mice, which express the perlecan transgene only in the cartilage to rescue the perinatal lethality of perlecan -deficient mice. Results: Although the BBB formation and function in the brain vasculature appeared to be unaffected in Perlecan -/- -Tg mice under healthy condition, Perlecan -/- -Tg mice demonstrated larger infarct volumes and more BBB leakage than control mice on post-surgery day (PSD) 2 after MCAO. Perlecan -/- -Tg mice exhibited less PDGFRβ-positive pericytes around the ischemic lesion on PSD 3 to 7 than control mice, suggesting that the perlecan deficiency suppressed pericyte activation. At a mechanistic level, integrin α5, a potential receptor for perlecan, was detectable in both endothelial cells and pericytes in the ischemic lesion, suggesting that endothelial cell-derived perlecan may regulate pericyte activation in response to ischemia through integrin α5. Conclusions: Our results suggest that perlecan is required for the activation of pericytes and thereby, contributing to the endothelial cell-pericyte integrity in the BBB maintenance after ischemic stroke.

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P-Glycoprotein-Mediated Transport of Itraconazole across the Blood-Brain Barrier

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.42.7.1738 ◽

1998 ◽

Vol 42 (7) ◽

pp. 1738-1744 ◽

Cited By ~ 72

Author(s):

Tetsuo Miyama ◽

Hitomi Takanaga ◽

Hirotami Matsuo ◽

Katsuhiro Yamano ◽

Koujirou Yamamoto ◽

...

Keyword(s):

Endothelial Cells ◽

Brain Tissue ◽

Blood Brain Barrier ◽

Half Life ◽

Liver Tissue ◽

Brain Barrier ◽

Brain Capillary ◽

P Glycoprotein ◽

Capillary Endothelial Cells ◽

The Brain

ABSTRACT The mechanism for the accumulation of itraconazole (ITZ) in its elimination from the brain was studied in rats and mice. The concentration of ITZ in liver tissue declined in parallel with the plasma ITZ concentration until 24 h after intravenous injection of the drug (half-life, 5 h); however, the ITZ in brain tissue rapidly disappeared (half-life, 0.4 h). The time profiles of the brain/plasma ITZ concentration ratio (Kp value) showed a marked overshooting, and the Kp value increased with increasing dose; these phenomena were not observed in the liver tissue. This finding indicates the occurrence of a nonlinear efflux of ITZ from the brain to the blood. Moreover, based on a pharmacokinetic model which hypothesized processes for both nonlinear and linear effluxes of ITZ from the brain to the blood, we found that the efflux rate constant in the saturable process was approximately sevenfold larger than that in the nonsaturable process. TheKp value for the brain tissue was significantly increased in the presence of ketoconazole or verapamil. The brainKp value for mdr1a knockout mice was also significantly increased compared with that of control mice. Moreover, the uptake of vincristine or vinblastine, both of which are substrates of the P glycoprotein (P-gp), into mouse brain capillary endothelial cells was also significantly increased by ITZ or verapamil. In conclusion, P-gp in the brain capillary endothelial cells participates in a process of active efflux of ITZ from the brain to the blood at the blood-brain barrier, and ITZ can be an inhibitor of various substrates of P-gp.

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Mrp4 Confers Resistance to Topotecan and Protects the Brain from Chemotherapy

Molecular and Cellular Biology ◽

10.1128/mcb.24.17.7612-7621.2004 ◽

2004 ◽

Vol 24 (17) ◽

pp. 7612-7621 ◽

Cited By ~ 299

Author(s):

Markos Leggas ◽

Masashi Adachi ◽

George L. Scheffer ◽

Daxi Sun ◽

Peter Wielinga ◽

...

Keyword(s):

Endothelial Cells ◽

Choroid Plexus ◽

Basolateral Membrane ◽

Cytotoxic Effects ◽

Brain Capillary ◽

Dual Localization ◽

Capillary Endothelial Cells ◽

The Brain

ABSTRACT The role of the multidrug resistance protein MRP4/ABCC4 in vivo remains undefined. To explore this role, we generated Mrp4-deficient mice. Unexpectedly, these mice showed enhanced accumulation of the anticancer agent topotecan in brain tissue and cerebrospinal fluid (CSF). Further studies demonstrated that topotecan was an Mrp4 substrate and that cells overexpressing Mrp4 were resistant to its cytotoxic effects. We then used new antibodies to discover that Mrp4 is unique among the anionic ATP-dependent transporters in its dual localization at the basolateral membrane of the choroid plexus epithelium and in the apical membrane of the endothelial cells of the brain capillaries. Microdialysis sampling of ventricular CSF demonstrated that localization of Mrp4 at the choroid epithelium is integral to its function in limiting drug penetration into the CSF. The topotecan resistance of cells overexpressing Mrp4 and the polarized expression of Mrp4 in the choroid plexus and brain capillary endothelial cells indicate that Mrp4 has a dual role in protecting the brain from cytotoxins and suggest that the therapeutic efficacy of central nervous system-directed drugs that are Mrp4 substrates may be improved by developing Mrp4 inhibitors.

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Evaluation of P-glycoprotein expression in pain relevant tissues: understanding translation of efflux from preclinical species to human

ADMET & DMPK ◽

10.5599/admet.4.3.305 ◽

2016 ◽

Vol 4 (3) ◽

pp. 261 ◽

Cited By ~ 1

Author(s):

Renu Singh Dhanikula ◽

Cyrla Hoffert ◽

Rebecca Grant ◽

Denis Projean ◽

Rosemarie Panetta ◽

...

Keyword(s):

Spinal Cord ◽

Endothelial Cells ◽

Double Labelling ◽

Sprague Dawley ◽

Glycoprotein P ◽

P Glycoprotein ◽

Preclinical Species ◽

Capillary Endothelial Cells ◽

The Central Nervous System ◽

Brain And Spinal Cord

<p class="ADMETabstracttext">Various efflux transporters, such as P-glycoprotein (P-gp) are now widely accepted to have profound influence on the disposition of substrates. Nevertheless, there is paucity of information about their expression and functionality in the pain relevant tissues (such as brain, spinal cord and dorsal root ganglia (DRG)) across various species. Therefore, our attempts were directed at evaluating P-gp expression in these tissues to understand its effect on the central nervous system (CNS) disposition. As a means of characterizing the normal tissue distribution of P-gp, immunohistochemistry was performed with two antibodies (C219 and H241) directed against different epitopes of MDR1 gene. Notable expression of P-gp was detected in the DRG of Sprague Dawley rat, Beagle Dog, Cynomolgous monkey as well as human. The expression of P-gp was observed in the CNS tissues with evident species differences, the expression of P-gp in human brain and spinal cord was lower than in rats and dogs but relatively comparable to that in monkeys. However, no species related differences were seen in the expression at the DRG level. Double-labelling using an antibody against a marker of endothelial cells confirmed that P-gp was exclusively localized in capillary endothelial cells. This study highlights the cross species similarities and differences in the expression of P-gp and thus serves as a vital step in understanding the translation of exposure of P-gp substrates to human.</p>

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Age influences susceptibility of brain capillary endothelial cells to La Crosse virus infection and cell death

Journal of Neuroinflammation ◽

10.1186/s12974-021-02173-4 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Rahul Basu ◽

Vinod Nair ◽

Clayton W. Winkler ◽

Tyson A. Woods ◽

Iain D. C. Fraser ◽

...

Keyword(s):

Endothelial Cells ◽

Cell Death ◽

Virus Infection ◽

La Crosse Virus ◽

Brain Capillary ◽

Adult Mice ◽

Age Related ◽

Capillary Endothelial Cells ◽

The Brain

Abstract Background A key factor in the development of viral encephalitis is a virus crossing the blood-brain barrier (BBB). We have previously shown that age-related susceptibility of mice to the La Crosse virus (LACV), the leading cause of pediatric arbovirus encephalitis in the USA, was associated with the ability of the virus to cross the BBB. LACV infection in weanling mice (aged around 3 weeks) results in vascular leakage in the olfactory bulb/tract (OB/OT) region of the brain, which is not observed in adult mice aged > 6–8 weeks. Thus, we studied age-specific differences in the response of brain capillary endothelial cells (BCECs) to LACV infection. Methods To examine mechanisms of LACV-induced BBB breakdown and infection of the CNS, we analyzed BCECs directly isolated from weanling and adult mice as well as established a model where these cells were infected in vitro and cultured for a short period to determine susceptibility to virus infection and cell death. Additionally, we utilized correlative light electron microscopy (CLEM) to examine whether changes in cell morphology and function were also observed in BCECs in vivo. Results BCECs from weanling, but not adult mice, had detectable infection after several days in culture when taken ex vivo from infected mice suggesting that these cells could be infected in vitro. Further analysis of BCECs from uninfected mice, infected in vitro, showed that weanling BCECs were more susceptible to virus infection than adult BCECs, with higher levels of infected cells, released virus as well as cytopathic effects (CPE) and cell death. Although direct LACV infection is not detected in the weanling BCECs, CLEM analysis of brain tissue from weanling mice indicated that LACV infection induced significant cerebrovascular damage which allowed virus-sized particles to enter the brain parenchyma. Conclusions These findings indicate that BCECs isolated from adult and weanling mice have differential viral load, infectivity, and susceptibility to LACV. These age-related differences in susceptibility may strongly influence LACV-induced BBB leakage and neurovascular damage allowing virus invasion of the CNS and the development of neurological disease.

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P-Glycoprotein and Breast Cancer Resistance Protein Restrict Apical-to-Basolateral Permeability of Human Brain Endothelium to Amyloid-β

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2009.42 ◽

2009 ◽

Vol 29 (6) ◽

pp. 1079-1083 ◽

Cited By ~ 73

Author(s):

Leon M Tai ◽

A Jane Loughlin ◽

David K Male ◽

Ignacio A Romero

Keyword(s):

Breast Cancer ◽

Human Brain ◽

Breast Cancer Resistance Protein ◽

Amyloid Β ◽

Cancer Resistance ◽

Glycoprotein P ◽

P Glycoprotein ◽

Resistance Protein ◽

The Brain

The clearance of amyloid beta (Aβ) from the brain represents a novel therapeutic target for Alzheimer's disease. Conflicting data exist regarding the contribution of adenosine triphosphatebinding cassette transporters to the clearance of Aβ through the blood-brain barrier. Therefore, we investigated whether Aβ could be a substrate for P-glycoprotein (P-gp) and/or for breast cancer resistance protein (BCRP) using a human brain endothelial cell line, hCMEC/D3. Inhibition of P-gp and BCRP increased apical-to-basolateral, but not basolateral-to-apical, permeability of hCMEC/D3 cells to 125l Aβ 1–40. Our in vitro data suggest that P-gp and BCRP might act to prevent the blood-borne Aβ 1–40 from entering the brain.

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Abstract MP17: Upregulating E2F1 Mitigates Senescence-Associated Phenotypes in Cultured Primary Endothelial Cells

Stroke ◽

10.1161/str.52.suppl_1.mp17 ◽

2021 ◽

Vol 52 (Suppl_1) ◽

Author(s):

Michael E Maniskas ◽

Yun-ju Lai ◽

Sean P Marrelli ◽

Louise D McCullough ◽

Jose F Moruno-manchon

Keyword(s):

Endothelial Cells ◽

Vascular Endothelial Cells ◽

Neurovascular Unit ◽

Glucose Deprivation ◽

Cerebral Hypoperfusion ◽

Aged Mouse ◽

Aged Mice ◽

Brain Vasculature ◽

Bilateral Carotid ◽

The Brain

Vascular contributions to cognitive impairment and dementia (VCID) includes multiple disorders that are identified by cognitive deficits secondary to cerebrovascular pathology. The risk of VCID is higher in people after the age of 70, and, currently, there is no effective treatment. Vascular endothelial cells (VEC) are critical components of the brain vasculature and neurovascular unit and their health is vital to the capacity of the brain vasculature to respond to stressors. However, aged VEC may enter an irreversible replicative-arrest state (senescence), which has been associated with dementia. E2F transcription factor 1 (E2F1) regulates cell cycle progression and DNA damage repair. Importantly, E2F1 deficiency is associated with cell senescence. We hypothesized that E2F1 downregulation contributes to senescence in the cerebral endothelium during aging. We used cultured primary VEC from young (4-months old, mo) and aged (18-mo) male and female mice for RNA sequencing, plasmid-based gene delivery, high-resolution microscopy, and (4-, 12-, and 18-mo) mice of the bilateral carotid artery stenosis (BCAS) model, which produces chronic cerebral hypoperfusion and recapitulates some of the features seen in patients with VCID. We found that overexpression of E2F1 reduced the levels of senescence-associated phenotypes in cultured VEC from young mice that were exposed to oxygen and glucose deprivation (p<0.001), which induces endothelial senescence. Our RNA seq data showed that the expression of E2f1 was reduced (~40%) in cultured primary VEC from aged mouse brains compared with young cells (p<0.001). E2F1 levels were reduced in the brains of aged mice. Interestingly, we found sex differences in E2F1 levels, with less protein levels (~30%) in males vs females (p<0.05), independently of age. Also, aged BCAS mice (1 month after surgery) had more severe senescence phenotypes, reduced cerebral blood flow, and worse memory deficits compared with control mice (p<0.05). The effect of BCAS was more prominent in aged mice compared with younger (4- and 12-mo) mice. In conclusion , our study identifies E2F1 as a potential regulator of endothelial senescence in mice and highlights the contribution of aging as an important factor in losing endothelial resilience.

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