Transepithelial fluxes of adenosine and 2′-deoxyadenosine across human renal proximal tubule cells: roles of nucleoside transporters hENT1, hENT2, and hCNT3

Elwi, Adam; Damaraju, Vijaya L.; Kuzma, Michelle; Mowles, Delores; Baldwin, Stephen A.; Young, James D.; Sawyer, Michael B.; Cass, Carol E.

doi:10.1152/ajprenal.90411.2008

Cited by 26 publications

(19 citation statements)

References 53 publications

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“…Proximal tubular epithelial cells generally have lower TEER consistent with a looser epithelium while distal tubular epithelial cells have higher TEER corresponding to a tighter epithelium. The steady state resistance of ∼100 Ω-cm 2 is consistent with other cultured renal tubular epithelial cells of proximal tubule origin (Wieser et al , 2008 and Elwi et al , 2009). To evaluate the barrier function, inulin leak was measured.…”

Section: Resultssupporting

confidence: 86%

A modular microfluidic bioreactor with improved throughput for evaluation of polarized renal epithelial cells

et al. 2016

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Most current microfluidic cell culture systems are integrated single use devices. This can limit throughput and experimental design options, particularly for epithelial cells, which require significant time in culture to obtain a fully differentiated phenotype. In addition, epithelial cells require a porous growth substrate in order to fully polarize their distinct apical and basolateral membranes. We have developed a modular microfluidic system using commercially available porous culture inserts to evaluate polarized epithelial cells under physiologically relevant fluid flow conditions. The cell-support for the bioreactor is a commercially available microporous membrane that is ready to use in a 6-well format, allowing for cells to be seeded in advance in replicates and evaluated for polarization and barrier function prior to experimentation. The reusable modular system can be easily assembled and disassembled using these mature cells, thus improving experimental throughput and minimizing fabrication requirements. The bioreactor consists of an apical microfluidic flow path and a static basolateral chamber that is easily accessible from the outside of the device. The basolateral chamber acts as a reservoir for transport across the cell layer. We evaluated the effect of initiation of apical shear flow on short-term intracellular signaling and mRNA expression using primary human renal epithelial cells (HRECs). Ten min and 5 h after initiation of apical fluid flow over a stable monolayer of HRECs, cells demonstrated increased phosphorylation of extracellular signal-related kinase and increased expression of interleukin 6 (IL-6) mRNA, respectively. This bioreactor design provides a modular platform with rapid experimental turn-around time to study various epithelial cell functions under physiologically meaningful flow conditions.

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Section: Resultssupporting

confidence: 86%

A modular microfluidic bioreactor with improved throughput for evaluation of polarized renal epithelial cells

et al. 2016

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“…Similar to recent studies of human kidney proximal tubule cells [108], ENTs are found on both the luminal and abluminal surfaces of BBB endothelial cells and on the basolateral and apical surfaces of BCSFB epithelial cells, whereas CNTs are exclusively expressed in abluminal and apical membranes, respectively. This vectorial distribution of NTs in BBB and BCSFB cells is mirrored by the asymmetric distribution of OCT, OAT and MRP transporters [109].…”

Section: Nts Of the Blood-brain Barrier And Choroid Plexussupporting

confidence: 85%

Molecular Biology of Nucleoside Transporters and their Distributions and Functions in the Brain

Parkinson¹,

Damaraju²,

Graham³

et al. 2011

CTMC

167

149

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Pyrimidine and purine nucleosides and their derivatives have critical functions and pharmacological applications in the brain. Nucleosides and nucleobases are precursors of nucleotides, which serve as the energy-rich currency of intermediary metabolism and as precursors of nucleic acids. Nucleosides (e.g., adenosine) and nucleotides are key signaling molecules that modulate brain function through interaction with cell surface receptors. Brain pathologies involving nucleosides and their metabolites range from epilepsy to neurodegenerative disorders and psychiatric conditions to cerebrovascular ischemia. Nucleoside analogs are used clinically in the treatment of brain cancer and viral infections. Nucleosides are hydrophilic molecules, and transportability across cell membranes via specialized nucleoside transporter (NT) proteins is a critical determinant of their metabolism and, for nucleoside drugs, their pharmacologic actions. In mammals, there are two types of nucleoside transport process: bidirectional equilibrative processes driven by chemical gradients, and unidirectional concentrative processes driven by sodium (and proton) electrochemical gradients. In mammals, these processes, both of which are present in brain, are mediated by members of two structurally unrelated membrane protein families (ENT and CNT, respectively). In this Chapter, we review current knowledge of cellular, physiological, pathophysiological and therapeutic aspects of ENT and CNT distribution and function in the mammalian brain, including studies with NT inhibitors and new research involving NT knockout and transgenic mice. We also describe recent progress in functional and molecular studies of ENT and CNT proteins, and summarize emerging evidence of other transporter families with demonstrated or potential roles in the transport of nucleosides and their derivatives in the brain.

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“…Single nucleotide polymorphisms involved in the metabolic pathway of nucleoside analogues have been identified and are postulated to influence drug exposure [44–47]. ENT1, ENT2, and concentrative nucleoside transporter 3 have been shown to influence in vitro distribution and accumulation of fludarabine [3,4,6]. These transporters are expressed in both target tissues and renal epithelial cells of the kidney and may impact drug exposure and disposition through several mechanisms [48,49].…”

Section: Discussionmentioning

confidence: 99%

“…Administered intravenously as a prodrug, fludarabine monophosphate (f-ara-AMP) undergoes rapid dephosphorylation in the plasma to the systemically circulating compound, f-ara-a. F-ara-a is then transported from the plasma into cells by several uptake transporters, including equilibrative nucleoside transporters (ENT1, ENT2) and the concentrative nucleoside transporters 3 [3–6]. In the cytoplasm, f-ara-a is sequentially phosphorylated to the active triphosphate species (f-ara-ATP), which inhibits DNA synthesis and RNA production, inducing apoptosis [1,2,7].…”

Section: Introductionmentioning

confidence: 99%

Pharmacokinetics and Model-Based Dosing to Optimize Fludarabine Therapy in Pediatric Hematopoietic Cell Transplant Recipients

Ivaturi

Dvorak

Chan

et al. 2017

Biology of Blood and Marrow Transplantation

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A prospective multicenter study was conducted to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of fludarabine plasma (f-ara-a) and intracellular triphosphate (f-ara-ATP) in children undergoing hematopoietic cell transplantation (HCT) and receiving fludarabine with conditioning. Plasma and peripheral blood mononuclear cells (PBMCs) were collected over the course of therapy for quantitation of f-ara-a and f-ara-ATP. Nonlinear mixed-effects modeling was used to develop the PK model, including identification of covariates impacting drug disposition. Data from a total of 133 children (median age, 5 years; range, .2 to 17.9) undergoing HCT for a variety of malignant and nonmalignant disorders were available for PK-PD modeling. The implementation of allometric scaling of PK parameters alone was insufficient to describe drug clearance, particularly in very young children. Renal impairment was predicted to increase drug exposure across all ages. The rate of f-ara-a entry into PBMCs (expressed in pmoles per million cells) decreased over the course of therapy, resulting in 78% lower f-ara-ATP after the fourth dose (1.7 pmoles/million cells [range, .2 to 7.2]) compared with first dose (7.9 pmoles/million cells [range, .7 to 18.2]). The overall incidence of treatment-related mortality (TRM) was low at 3% and 8% at days 60 and 360, respectively, and no association with f-ara-a exposure and TRM was found. In the setting of malignancy, disease-free survival was highest at 1 year after HCT in subjects achieving a systemic f-ara-a cumulative area under the curve (cAUC) greater than 15 mg*hour/L compared to patients with a cAUC less than 15 mg*hour/L (82.6% versus 52.8% P = .04). These results suggest that individualized model-based dosing of fludarabine in infants and young children may reduce morbidity and mortality through improved rates of disease-free survival and limiting drug-related toxicity. ClinicalTrials.gov Identifier: NCT01316549

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Transepithelial fluxes of adenosine and 2′-deoxyadenosine across human renal proximal tubule cells: roles of nucleoside transporters hENT1, hENT2, and hCNT3

Cited by 26 publications

References 53 publications

A modular microfluidic bioreactor with improved throughput for evaluation of polarized renal epithelial cells

A modular microfluidic bioreactor with improved throughput for evaluation of polarized renal epithelial cells

Molecular Biology of Nucleoside Transporters and their Distributions and Functions in the Brain

Pharmacokinetics and Model-Based Dosing to Optimize Fludarabine Therapy in Pediatric Hematopoietic Cell Transplant Recipients

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