title: Positive cross talk between protein kinase D and β-catenin in intestinal epithelial cells: impact on β-catenin nuclear localization and phosphorylation at Ser552.
abstract: Given the fundamental role of β-catenin signaling in intestinal epithelial cell proliferation and the growth-promoting function of protein kinase D1 (PKD1) in these cells, we hypothesized that PKDs mediate cross talk with β-catenin signaling. The results presented here provide several lines of evidence supporting this hypothesis. We found that stimulation of intestinal epithelial IEC-18 cells with the G protein-coupled receptor (GPCR) agonist angiotensin II (ANG II), a potent inducer of PKD activation, promoted endogenous β-catenin nuclear localization in a time-dependent manner. A significant increase was evident within 1 h of ANG II stimulation (P< 0.01), peaked at 4 h (P< 0.001), and declined afterwards. GPCR stimulation also induced a marked increase in β-catenin-regulated genes and phosphorylation at Ser(552) in intestinal epithelial cells. Exposure to preferential inhibitors of the PKD family (CRT006610 or kb NB 142-70) or knockdown of the isoforms of the PKD family prevented the increase in β-catenin nuclear localization and phosphorylation at Ser(552) in response to ANG II. GPCR stimulation also induced the formation of a complex between PKD1 and β-catenin, as shown by coimmunoprecipitation that depended on PKD1 catalytic activation, as it was abrogated by cell treatment with PKD family inhibitors. Using transgenic mice that express elevated PKD1 protein in the intestinal epithelium, we detected a marked increase in the localization of β-catenin in the nucleus of crypt epithelial cells in the ileum of PKD1 transgenic mice, compared with nontransgenic littermates. Collectively, our results identify a novel cross talk between PKD and β-catenin in intestinal epithelial cells, both in vitro and in vivo.
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, Los Angeles, California;
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, Los Angeles, California;
authors.forename: Liang
authors.initials: L
authors.lastname: Han
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, Los Angeles, California; CURE, Digestive Diseases Research Center, Los Angeles, California; Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California.
authors.forename: James
authors.initials: J
authors.lastname: Sinnett-Smith
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, Los Angeles, California;
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Han
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, Los Angeles, California;
authors.forename: Jan V
authors.initials: JV
authors.lastname: Stevens
authors.affiliation: CURE, Digestive Diseases Research Center, Los Angeles, California; erozengurt@mednet.ucla.edu.
authors.forename: Nora
authors.initials: N
authors.lastname: Rozengurt
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, Los Angeles, California; Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Young
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, Los Angeles, California; CURE, Digestive Diseases Research Center, Los Angeles, California; Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California; and Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, California.
authors.forename: Enrique
authors.initials: E
authors.lastname: Rozengurt
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015151:Immunoblotting; D047468:Immunoprecipitation; D007413:Intestinal Mucosa / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D034741:RNA, Small Interfering; D051381:Rats; D020239:Receptor Cross-Talk / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000378:metabolism; D014162:Transfection; D051176:beta Catenin / Q000378:metabolism*
chemical_list: C495267:CTNNB1 protein, mouse; C495268:Ctnnb1 protein, rat; D034741:RNA, Small Interfering; D051176:beta Catenin; D012694:Serine; C089212:protein kinase D; D011493:Protein Kinase C
keywords: CRT006610; G protein-coupled receptors; IEC-18 cells; PKA; PKD family inhibitors; PKD1 transgenic mice; angiotensin II; kb NB 142-70