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- Title
Tumor suppressor gene adenomatous polyposis coli downregulates intestinal transport.
- Authors
Rexhepaj, Rexhep; Rotte, Anand; Gu, Shuchen; Michael, Diana; Pasham, Venkanna; Wang, Kan; Kempe, Daniela; Ackermann, Teresa; Brücher, Björn; Fend, Falko; Föller, Michael; Lang, Florian
- Abstract
Loss of function mutations of the tumor suppressor gene adenomatous polyposis coli (APC) underly the familial adenomatous polyposis. Mice carrying an inactivating mutation in the apc gene ( apc) similarly develop intestinal polyposis. APC is effective at least in part by degrading β-catenin and lack of APC leads to markedly enhanced cellular β-catenin levels. β-Catenin has most recently been shown to upregulate the Na/K ATPase. The present study, thus, explored the possibility that APC could influence intestinal transport. The abundance and localization of β-catenin were determined utilizing Western blotting and confocal microscopy, the activity of the electrogenic glucose carrier (SGLT1) was estimated from the glucose-induced current in jejunal segments utilizing Ussing chamber experiments and the Na/H exchanger (NHE3) activity from Na-dependent re-alkalinization of cytosolic pH (ΔpH) following an ammonium pulse employing BCECF fluorescence. As a result, β-catenin abundance in intestinal tissue was significantly higher in apc mice than in wild-type mice ( apc). The β-catenin protein was localized in the basolateral membrane. Both, the glucose-induced current and ΔpH were significantly higher in apc mice than in apc mice. In conclusion, intestinal electrogenic transport of glucose and intestinal Na/H exchanger activity are both significantly enhanced in apc mice, pointing to a role of APC in the regulation of epithelial transport.
- Subjects
TUMOR suppressor genes; BLOOD sugar; CONFOCAL microscopy; WESTERN immunoblotting; EPITHELIUM; HYDROGEN-ion concentration
- Publication
Pflügers Archiv: European Journal of Physiology, 2011, Vol 461, Issue 5, p527
- ISSN
0031-6768
- Publication type
Article
- DOI
10.1007/s00424-011-0945-2