CCK causes PKD1 activation in pancreatic acini by signaling through PKC-delta and PKC-independent pathways.
Protein kinase D1 (PKD1) is involved in cellular processes including protein secretion, proliferation and apoptosis. Studies suggest PKD1 is activated by various stimulants including gastrointestinal (GI) hormones/neurotransmitters and growth factors in a protein kinase C (PKC)-dependent pathway. However, little is known about the mechanisms of PKD1 activation in physiologic GI tissues. We explored PKD1 activation by GI hormones/neurotransmitters and growth factors and the mediators involved in rat pancreatic acini. Only hormones/neurotransmitters activating phospholipase C caused PKD1 phosphorylation (S916, S744/748). CCK activated PKD1 and caused a time- and dose-dependent increase in serine phosphorylation by activation of high- and low-affinity CCK(A) receptor states. Inhibition of CCK-stimulated increases in phospholipase C, PKC activity or intracellular calcium decreased PKD1 S916 phosphorylation by 56%, 62% and 96%, respectively. PKC inhibitors GF109203X/Go6976/Go6983/PKC-zeta pseudosubstrate caused a 62/43/49/0% inhibition of PKD1 S916 phosphorylation and an 87/13/82/0% inhibition of PKD1 S744/748 phosphorylation. Expression of dominant negative PKC-delta, but not PKC-epsilon, or treatment with PKC-delta translocation inhibitor caused marked inhibition of PKD phosphorylation. Inhibition of Src/PI3K/MAPK/tyrosine phosphorylation had no effect. In unstimulated cells, PKD1 was mostly located in the cytoplasm. CCK stimulated translocation of total and phosphorylated PKD1 to the membrane. These results demonstrate that CCK(A) receptor activation leads to PKD activation by signaling through PKC-dependent and PKC-independent pathways.
Berna
Marc J
MJ
Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health (NIH), Bethesda, MD 20892-1804, USA.
Hoffmann
K Martin
KM
Tapia
Jose A
JA
Thill
Michelle
M
Pace
Andrea
A
Mantey
Samuel A
SA
Jensen
Robert T
RT
D000818:Animals; D001839:Bombesin / Q000494:pharmacology; D002118:Calcium / Q000172:deficiency; D002217:Carbachol / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D046790:Pancreas, Exocrine / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D010768:Phosphoserine / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011493:Protein Kinase C; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011949:Receptors, Cholecystokinin / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D010738:Type C Phospholipases / Q000378:metabolism
D006133:Growth Substances; D007527:Isoenzymes; D047428:Protein Kinase Inhibitors; D011949:Receptors, Cholecystokinin; D010768:Phosphoserine; D019000:Phosphotyrosine; D002217:Carbachol; D002766:Cholecystokinin; D011494:Protein Kinases; C089212:protein kinase D; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D013755:Tetradecanoylphorbol Acetate; D001839:Bombesin; D002118:Calcium