Abstract
The effects of glucagon-like peptide 2 (GLP-2) on expression and activity of jejunal multidrug resistance-associated protein 2 (Mrp2; Abcc2) and glutathione transferase (GST) were evaluated. After GLP-2 treatment (12 μg/100 g b.wt. s.c., every 12 h, for 5 consecutive days), Mrp2 and the α class of GST proteins and their corresponding mRNAs were increased, suggesting a transcriptional regulation. Mrp2 was localized at the apical membrane of the enterocyte in control and GLP-2 groups, as detected by confocal immunofluorescence microscopy. As a functional assay, everted intestinal sacs were incubated in the presence of 1-chloro-2,4-dinitrobenzene in the mucosal compartment, and the glutathione-conjugated derivative, dinitrophenyl-S-glutathione (DNP-SG; model Mrp2 substrate), was detected in the same compartment by high-performance liquid chromatography. A significant increase in apical secretion of DNP-SG was detected in the GLP-2 group, consistent with simultaneous up-regulation of Mrp2 and GST. GLP-2 also promoted an increase in cAMP levels as detected in homogenates of intestinal mucosa. Treatment of rats with 2′,3′-dideoxyadenosine (DDA), a specific inhibitor of adenylyl cyclase, abolished the increase in cAMP levels and Mrp2 protein promoted by GLP-2, suggesting cAMP as a mediator of Mrp2 modulation. Increased expression of Mrp2 and cAMP levels in response to GLP-2 occurred not only at the tip but also at the middle region of the villus, where constitutive expression of Mrp2 is normally low. In conclusion, our study suggests a role for GLP-2 in the prevention of cell toxicity of the intestinal mucosa by increasing Mrp2 chemical barrier function.
Footnotes
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This work was supported by the Agencia Nacional de Promoción Científica y Tecnológica [Proyecto de Investigación Científica y Tecnológica Grant 05-26306], Consejo Nacional de Investigaciones Científicas y Técnicas [Proyecto de Investigación Plurianual Grant 6442], and Universidad Nacional de Rosario [Proyecto de Investigación y Desarrollo Grant BIO-112].
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.110.171041.
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ABBREVIATIONS:
- GLP-2
- glucagon-like peptide 2
- GLP-2R
- GLP-2 receptor
- GST
- glutathione transferase
- Mrp2
- multidrug resistance-associated protein 2
- PKA
- protein kinase A
- AP-1
- activator protein-1
- CDNB
- 1-chloro-2,4-dinitrobenzene
- BBM
- brush border membrane
- ZO-1
- zonula occludens 1
- DNP-SG
- dinitrophenyl-S-glutathione
- RT-PCR
- real-time polymerase chain reaction
- PBS
- phosphate-buffered saline
- DTT
- dithiothreitol.
- Received June 3, 2010.
- Accepted August 17, 2010.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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