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Functional expression of rat ABCG2 on the luminal side of brain capillaries and its enhancement by astrocyte-derived soluble factor(s).

Authors: Hori, S  Ohtsuki, S  Tachikawa, M  Kimura, N  Kondo, T  Watanabe, M  Nakashima, E  Terasaki, T 
Citation: Hori S, etal., J Neurochem 2004 Aug;90(3):526-36.
Pubmed: (View Article at PubMed) PMID:15255930
DOI: Full-text: DOI:10.1111/j.1471-4159.2004.02537.x

The purpose of the present study was to clarify the expression, transport properties and regulation of ATP-binding cassette G2 (ABCG2) transporter at the rat blood-brain barrier (BBB). The rat homologue of ABCG2 (rABCG2) was cloned from rat brain capillary fraction. In rABCG2-transfected HEK293 cells, rABCG2 was detected as a glycoprotein complex bridged by disulfide bonds, possibly a homodimer. The protein transported mitoxantrone and BODIPY-prazosin. In rat brain capillary fraction, rABCG2 protein was also detected as a glycosylated and disulfide-linked complex. Immunohistochemical analysis revealed that rABCG2 was localized mainly on the luminal side of rat brain capillaries, suggesting that rABCG2 is involved in brain-to-blood efflux transport. For the regulation study, conditionally immortalized rat brain capillary endothelial (TR-BBB13), astrocyte (TR-AST4) and pericyte (TR-PCT1) cell lines were used as an in vitro BBB model. Following treatment of TR-BBB13 cells with conditioned medium of TR-AST4 cells, the Ko143 (an ABCG2-specific inhibitor)-sensitive transport activity and rABCG2 mRNA level were significantly increased, whereas conditioned medium of TR-PCT1 cells had no effect. These results suggest that rat brain capillaries express functional rABCG2 protein and that the transport activity of the protein is up-regulated by astrocyte-derived soluble factor(s) concomitantly with the induction of rABCG2 mRNA.

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RGD Object Information
RGD ID: 1304349
Created: 2004-12-22
Species: All species
Last Modified: 2004-12-22
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.