title: Regulatory subunit I-controlled protein kinase A activity is required for apical bile canalicular lumen development in hepatocytes.
abstract: Signaling via cAMP plays an important role in apical cell surface dynamics in epithelial cells. In hepatocytes, elevated levels of cAMP as well as extracellular oncostatin M stimulate apical lumen development in a manner that depends on protein kinase A (PKA) activity. However, neither the identity of PKA isoforms involved nor the mechanisms of the cross-talk between oncostatin M and cAMP/PKA signaling pathways have been elucidated. Here we demonstrate that oncostatin M and PKA signaling converge at the level of the PKA holoenzyme downstream of oncostatin M-stimulated MAPK activation. Experiments were performed with chemically modified cAMP analogues that preferentially target regulatory subunit (R) I or RII holoenzymes, respectively, in hepatocytes. The data suggest that the dissociation of RI- but not RII-containing holoenzymes, as well as catalytic activity of PKA, is required for apical lumen development in response to elevated levels of cAMP and oncostatin M. However, oncostatin M signaling does not stimulate PKA holoenzyme dissociation in living cells. Based on pharmacological and cell biological studies, it is concluded that RI-controlled PKA activity is essential for cAMP- and oncostatin M-stimulated development of apical bile canalicular lumens.
authors.affiliation: Department of Cell Biology, Section of Membrane Cell Biology, University Medical Center Groningen, University of Groningen, Groningen 9713AV, The Netherlands.
authors.forename: Kacper A
authors.initials: KA
authors.lastname: Wojtal
authors.forename: Mandy
authors.initials: M
authors.lastname: Diskar
authors.forename: Friedrich W
authors.initials: FW
authors.lastname: Herberg
authors.forename: Dick
authors.initials: D
authors.lastname: Hoekstra
authors.forename: Sven C D
authors.initials: SC
authors.lastname: van Ijzendoorn
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D001648:Bile Canaliculi / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology; D016764:Cell Polarity / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit / Q000378:metabolism; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit / Q000378:metabolism*; D004735:Energy Transfer / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D020035:Holoenzymes / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D053683:Oncostatin M / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D020035:Holoenzymes; D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D053683:Oncostatin M; D000242:Cyclic AMP; D048052:Mitogen-Activated Protein Kinase 3