The function of Gp170, the multidrug-resistance gene product, in the brush border of rat intestinal mucosa

doi:10.1016/0016-5085(92)90173-V

Gastroenterology

Volume 102, Issue 3, March 1992, Pages 879-885

https://doi.org/10.1016/0016-5085(92)90173-V Get rights and content

Abstract

Gp170 is a transmembrane glycoprotein that is overexpressed in multidrug-resistant tumor cells and is present in the apical plasma membrane domain of small intestinal mucosal cells. The function of Gp170 was studied in the small intestine of the rat. Jejunal and ileal brush border membrane vesicles, but not basolateral membrane vesicles, manifested adenosine triphosphate (ATP)-dependent transport of daunomycin, a substrate for Gp170, and contained a ~170-kilodalton protein that reacts with anti-Gp170 monoclonal antibody. Whereas ATP supported daunomycin transport, nonhydrolyzable ATP analogues were ineffective. ATP-dependent daunomycin transport by brush border vesicles was unidirectional (inside to outside) and temperature dependent and was blocked by Gp170 inhibitors but not by taurocholate or bromsulphalein glutathione. Studies using everted small intestine revealed transport of rhodamine 123, a Gp170 substrate, from the serosal surface through the mucosa and inhibition by Gp170 inhibitors. These results suggest that Gp170 in rat small intestinal brush border membrane vesicles is an ATP-dependent efflux pump responsible for the transport of Gp170 substrates into the small intestinal lumen. Gp170 may protect against exogenously derived potentially damaging hydrophobic cations and contribute to the rarity of small intestinal cancer in humans and many animals.

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Bioavailability of many clinically relevant drugs is modulated by the activity of efflux transporters expressed in the epithelial lining of the intestine [1,2]. P-glycoprotein (P-gp, also known as ABCB1), a member of the ATP-binding cassette family of transporters, is located in the apical membrane of intestinal epithelial cells [3,4] and serves as an important determinant of the disposition of many orally administered drugs [5–9]. There is, thus, a considerable interest in predicting the P-gp-mediated elimination of drug candidates and assessing the drug-drug interactions involving P-gp substrates and inhibitors/inducers in the intestinal epithelium.
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An in situ ileum loop (60 cm length) was isolated in each rat at 60 min after reperfusion and was homogenized in buffer containing 0.05 mg/mL phenylmethylsulfonylfluoride, 300 mM mannitol, 12 mM Tris, and 5 mM EGTA (pH 7.1) with a tissue homogenizer. Brush border membrane (BBM) fractions were prepared from the ileum using magnesium chloride precipitation (Iida et al., 2006; Stieger and Murer, 1983; Hsing et al., 1992). Protein was determined by a method using the Micro BCA Protein Assay Reagent Kit (Thermo, Rockford, USA).
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: Research in the authors' laboratory was supported by grants from the National Institutes of Health (DK 35652 and 34928) and the Gail I. Zuckerman Foundation.

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The function of Gp170, the multidrug-resistance gene product, in the brush border of rat intestinal mucosa

Abstract

J Biol Chem

Cell

J Biol Chem

J Biol Chem

J Biol Chem

J Biol Chem

ATP-dependent primary active transport of cysteinyl leukotrienes across liver canalicular membrane

J Biol Chem

Biochem Pharmacol

Reduced permeability in CHO cells as a mechanism of resistance to colchicine

J Cell Physiol

Potentiation of drug effect by Tween 80 in Chinese hamster cells resistant to actinomycin D and daunomycin

Cancer Res

Cross resistance between vinca alkaloids and anthracyclines in Ehrlich ascutes tumor in vivo

Cancer Chemother Rep

Multidrug resistance in cancer

Sci Am

Multidrug resistance genes, P-glycoprotein and the liver

Hepatology

Amplification of specific DNA sequences correlates with multidrug resistance in Chinese hamster cells

Nature

Isolation and expression of a complementary DNA that confers multidrug resistance

Nature

Active efflux of daunorubican and adriamycin in sensitive and resistant sublines of P388 leukemia

Cancer Res