Intracellular mechanisms mediating the anti-apoptotic action of gastrin
Section snippets
Materials and methods
Plasmids. The plasmid expressing 3× IRS-Luc [13] was a gift of K. Guan (Ann Arbor, MI). The FOXO1 (FKHR) expressing vector was a gift from F.G. Barr (Philadelphia, PA) [13]. Gal4-ElkC [16] was a gift from R. Treisman (London, UK). pCMV-βGal was a gift from M. Uhler (Ann Arbor, MI). Recombinant BAD [12] was a gift from G. Nunez (Ann Arbor, MI).
Cell culture, transient transfection, and luciferase assays. For our experiments we used the rat exocrine pancreatic cell line AR4-2J (obtained from
Results
We previously observed that gastrin (G17) inhibits apoptosis of the AR4-2J rat acinar cell line through the phosphorylation and activation of protein kinase B/Akt [8]. In this study, we further dissected the mechanisms that mediate the anti-apoptotic action of gastrin in the AR4-2J cells. We confirmed the involvement of specific CCKB receptors in gastrin induction of Akt activation. D2 (10 nM), a specific CCKB receptor antagonist [5], inhibited gastrin (10 nM)-induced phosphorylation of Akt (Fig.
Discussion
The peptide hormone gastrin regulates numerous, complex cellular functions such as growth, proliferation, and secretion [1], [2], [3], [4]. In previous studies we reported that gastrin induces the Akt signal transduction pathway and that this effect leads to inhibition of AR4-2J cell apoptosis [8].
In this study, we show that gastrin induction of Akt leads to the phosphorylation, both in vitro and in vivo, of BAD, a well-characterized pro-apoptotic protein, which is phosphorylated and
Acknowledgments
The authors thank Thomas Witham, Daniel Miller, and Jace Nielsen for technical assistance. This work was supported by National Institute of Diabetes and Digestive and Kidney Disease (NIDDK) Grant RO1-DK-058312 (to A. Todisco) and by funds from the University of Michigan Gastrointestinal Peptide Research Center (NIH Grant P30DK34933).
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Hypergastrinemia increases gastric epithelial susceptibility to apoptosis
2008, Regulatory PeptidesRole of gastrin peptides in carcinogenesis
2007, Cancer LettersCitation Excerpt :Proliferation of epithelial cells within Barrett’s oesophagus biopsies is also increased by treatment with G17, via the CCK-2R [111], suggesting a possible role for gastrin in promoting growth of cells within pre-malignant lesions. In addition to enhancing growth through positive signals, gastrin inhibits apoptosis [112]. This occurs through phosphorylation of phosphokinase B (PKB)/Akt via a pathway dependent on PI3K but independent of MAPK [113], and via a PKC-δ-dependent pathway that causes degradation of the inhibitor of NFκB, IκB-α [27,114].
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