Inflammatory Regulation of ATP Binding Cassette Efflux Transporter Expression and Function in Microglia

Gibson, Christopher J.; Hossain, Muhammad M.; Richardson, Jason R.; Aleksunes, Lauren M.

doi:10.1124/jpet.112.196543

Cited by 59 publications

(37 citation statements)

References 57 publications

(71 reference statements)

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“…The fluorescent substrate calcein AM was used to characterize the transport activity of WT-MRP2 and variants in Flp-In 293 cells (18, 20). In brief, cell suspensions (prepared in medium, 500,000 cells/ml) were loaded with calcein AM (0.5, 2 or 10 μM) for 30 min at 37°C, 5% CO 2 ( uptake period ).…”

Section: Methodsmentioning

confidence: 99%

In Vitro Transport Activity and Trafficking of MRP2/ABCC2 Polymorphic Variants

2017

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Purpose Multidrug resistance-associated protein 2 (MRP2/ABCC2) is an efflux pump that removes drugs and chemicals from cells. We sought to characterize the expression, trafficking and in vitro activity of seven single nucleotide polymorphisms (SNPs) in the ABCC2 gene. Methods ABCC2 SNPs were generated using site-directed mutagenesis and stably expressed in Flp-In HEK293 cells, which allows targeted insertion of transgenes within the genome. Total and cell surface expression of MRP2 as well as accumulation of substrates (calcein AM and 5(6)-carboxy-2′,7′-dichlorofluorescein diacetate, CDCF) were quantified in cells or inverted membrane vesicles expressing wild-type (WT) or variant forms. Results The cell surface expression of the C-24T-, G1249A-, G3542T-, T3563A-, C3972T- and G4544A-MRP2 variants was similar to WT-MRP2. While expression was similar, transport of calcein AM was enhanced in cells expressing the G3542T-, T3563A-, C3972T-, and G4544A-MRP2 variants. By comparison, cells expressing the C2366T-MRP2 variant had 40-50% lower surface expression, which increased the accumulation of calcein AM up to 3-fold. Accumulation of CDCF in inverted membrane vesicles expressing the C2366T-MRP2 variant was also reduced by 50%. In addition, the G1249A-MRP2 variant had decreased transport of CDCF. Conclusions Taken together, these data demonstrate that genetic variability in the ABCC2 gene influences the in vitro expression, trafficking, and transport activity of MRP2.

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Section: Methodsmentioning

confidence: 99%

In Vitro Transport Activity and Trafficking of MRP2/ABCC2 Polymorphic Variants

2017

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“…Inflammatory events may affect mRNA/protein expression of these transporters (57). For example, in vitro studies have shown that LPS-treated microglia express decreased mRNA/protein levels of several ABC transporters such as P-gp, Bcrp, Mrp2, Mrp4, and Mrp5 (58). Expression of these transporters indicates that microglia may play a role in CNS drug permeation and distribution; however, more studies are required to elucidate the role of microglia in drug uptake into the CNS.…”

Section: Components Of the Nvumentioning

confidence: 99%

Transporters at CNS Barrier Sites: Obstacles or Opportunities for Drug Delivery?

Sanchez-Covarrubias¹,

Slosky²,

Thompson³

et al. 2014

CPD

203

137

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The blood-brain barrier (BBB) and blood-cerebrospinal fluid (BCSF) barriers are critical determinants of CNS homeostasis. Additionally, the BBB and BCSF barriers are formidable obstacles to effective CNS drug delivery. These brain barrier sites express putative influx and efflux transporters that precisely control permeation of circulating solutes including drugs. The study of transporters has enabled a shift away from “brute force” approaches to delivering drugs by physically circumventing brain barriers towards chemical approaches that can target specific compounds of the BBB and/or BCSF barrier. However, our understanding of transporters at the BBB and BCSF barriers has primarily focused on understanding efflux transporters that efficiently prevent drugs from attaining therapeutic concentrations in the CNS. Recently, through the characterization of multiple endogenously expressed uptake transporters, this paradigm has shifted to the study of brain transporter targets that can facilitate drug delivery (i.e., influx transporters). Additionally, signaling pathways and trafficking mechanisms have been identified for several endogenous BBB/BCSF transporters, thereby offering even more opportunities to understand how transporters can be exploited for optimization of CNS drug delivery. This review presents an overview of the BBB and BCSF barrier as well as the many families of transporters functionally expressed at these barrier sites. Furthermore, we present an overview of various strategies that have been designed and utilized to deliver therapeutic agents to the brain with a particular emphasis on those approaches that directly target endogenous BBB/BCSF barrier transporters.

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“…We have observed that ACN accumulates more in astrocytes and it is known that these cells express CYP2E1 (Montoliu et al, 1995), however it is unknown whether microglia express CYP2E1. Additionally astrocytes and microglia express multidrug resistance-associated protein 1 (Mrp 1, ABCC1), an ATP-driven pump that mediates export of organic anions and GSH conjugates (Gibson et al, 2012; Mercier et al, 2004). Astrocytes are closely associated to the BBB, allowing for ACN –GSH conjugates to be removed from the brain by Mrp 1 or other related transporters.…”

Section: Discussionmentioning

confidence: 99%

Differential response to acrylonitrile toxicity in rat primary astrocytes and microglia

Caito

Aschner

2013

NeuroToxicology

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Acrylonitrile (ACN) is a widely used chemical in the production of plastics, resins, nitriles, acrylic fibers, synthetic rubber and acrylamide. While acute high level exposures to ACN are known to be lethal, chronic low dose exposures causes glial cell tumors in rats. Recently, these glial tumors have been characterized as microglial in origin. While effects of ACN on astrocytes, the more numerous glial cell, have been investigated, the effects on microglia are unknown. This study was conducted to compare the responses of astrocytes and microglia to ACN treatment in vitro to address differential sensitivities and adaptive responses to this toxic chemical. Cell viability, ACN uptake, lipid peroxidation byproducts (F2-isoprostanes), glutathione (GSH) levels and expression of NF-E2-related factor 2 (Nrf2) were evaluated in primary rat microglia and astrocytes following ACN treatment. Results indicate that microglia are more sensitive to ACN than astrocytes, accumulating less ACN while demonstrating higher F2-isoprostane levels. GSH levels were up-regulated in both cell types, as a protective mechanism against ACN-induced oxidative stress, while Nrf2 levels were only induced in microglia. Our data suggest that microglia and astrocytes exhibit different sensitivities and responses to ACN, which are linked to the intracellular thiol status inherent to each of these cell types.

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Inflammatory Regulation of ATP Binding Cassette Efflux Transporter Expression and Function in Microglia

Cited by 59 publications

References 57 publications

In Vitro Transport Activity and Trafficking of MRP2/ABCC2 Polymorphic Variants

In Vitro Transport Activity and Trafficking of MRP2/ABCC2 Polymorphic Variants

Transporters at CNS Barrier Sites: Obstacles or Opportunities for Drug Delivery?

Differential response to acrylonitrile toxicity in rat primary astrocytes and microglia

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