The inflammatory mediator leukotriene D4 induces beta-catenin signaling and its association with antiapoptotic Bcl-2 in intestinal epithelial cells.
Increased levels of the inflammatory mediator leukotriene D4 (LTD4) are present at sites of inflammatory bowel disease, and such areas also exhibit an increased risk for subsequent cancer development. It is known that LTD4 affects the expression of many proteins that influence survival and proliferation of intestinal epithelial cells. We demonstrate here that after LTD4 exposure, beta-catenin translocates to the nucleus where it signals activation of the TCF/LEF family of transcription factors. These events are mediated via a phosphatidylinositol 3-kinase-dependent phosphorylation of the inhibitory Ser-9 residue of glycogen synthase kinase 3beta. We also show that in the presence of LTD4, free beta-catenin translocates to the mitochondria where it associates with the cell survival protein Bcl-2. We hypothesize that LTD4 may enhance cell survival via activation of beta-catenin signaling, in particular, by promoting the association of beta-catenin with Bcl-2 in the mitochondria. Similar to Wnt-1 signaling, LTD4 signals an increased level of free beta-catenin and elevated TCF/LEF promotor activity. This work in intestinal epithelial cells further lends credence to the idea that inflammatory signaling pathways are intrinsically linked with potential oncogenic signals involved in cell survival and apoptosis.
Mezhybovska
Maryna
M
Experimental Pathology, Department of Laboratory Medicine, Lund University, University Hospital Malmö, SE-205 02 Malmö, Sweden.
Wikström
Katarina
K
Ohd
John F
JF
Sjölander
Anita
A
D017209:Apoptosis / Q000502:physiology*; D002460:Cell Line; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007413:Intestinal Mucosa / Q000201:enzymology / Q000378:metabolism; D017998:Leukotriene D4 / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D021381:Protein Transport; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D051820:TCF Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
D019253:Proto-Oncogene Proteins c-bcl-2; D051820:TCF Transcription Factors; D051176:beta Catenin; D017998:Leukotriene D4; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3