Regulatory subunit I-controlled protein kinase A activity is required for apical bile canalicular lumen development in hepatocytes.
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.
Wojtal
Kacper A
KA
Department of Cell Biology, Section of Membrane Cell Biology, University Medical Center Groningen, University of Groningen, Groningen 9713AV, The Netherlands.
Diskar
Mandy
M
Herberg
Friedrich W
FW
Hoekstra
Dick
D
van Ijzendoorn
Sven C D
SC
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
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