title: PKD, PKD2, and p38 MAPK mediate Hsp27 serine-82 phosphorylation induced by neurotensin in pancreatic cancer PANC-1 cells.
abstract: It is widely recognized that Hsp27 is a downstream substrate of the p38 MAPK cascade whereas the role of PKD family members in mediating receptor-stimulated Hsp27 Ser-82 phosphorylation has not been evaluated. Here, we show that neurotensin induced a rapid and striking increase in Hsp27 Ser-82 phosphorylation in PANC-1 cells, which was closely correlated with stimulation of activation loop phosphorylation of PKDs and p38 MAPK Thr180/Tyr182 phosphorylation. Treatment of PANC-1 cells with either the selective PKC inhibitor GF-I or the p38 MAPK inhibitor SB202190 partially reduced neurotensin-induced Hsp27 Ser-82 phosphorylation. However, treatment of the cells with a combination of GF-I and SB202190 virtually abolished neurotensin-induced Hsp27 Ser-82 phosphorylation. Overexpression of PKD in stably transfected PANC-1 cells increased the magnitude and prolonged the duration of Hsp27 Ser-82 phosphorylation in response to neurotensin. Either PKD or PKD2 gene silencing utilizing siRNAs targeting distinct PKD or PKD2 sequences reduced neurotensin-stimulated Hsp27 Ser-82 phosphorylation, but cotransfection of siRNAs targeting both, PKD and PKD2, markedly decreased neurotensin-induced Hsp27 Ser-82 phosphorylation. Knockdown of PKD and PKD2 abolished Hsp27 phosphorylation in cells treated with SB202190. Thus, neurotensin induces Hsp27 Ser-82 phosphorylation through p38 MAPK- and PKC/PKD-dependent pathways in PANC-1 cells. Our results demonstrate, for the first time, that neurotensin induces a striking increase in Hsp27 phosphorylation on Ser-82 in PANC-1 cells through convergent p38 MAPK, PKD, and PKD2 signaling.
authors.affiliation: Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine; CURE: Digestive Diseases Research Center and Molecular Biology Institute, University of California, Los Angeles, California 90095, USA.
authors.forename: Jingzhen
authors.initials: J
authors.lastname: Yuan
authors.forename: Enrique
authors.initials: E
authors.lastname: Rozengurt
mesh_terms: D000841:Anisomycin / Q000494:pharmacology; D021441:Carcinoma, Pancreatic Ductal / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009363:Neoplasm Proteins / Q000502:physiology*; D009496:Neurotensin / Q000494:pharmacology*; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D000091283:Protein Kinase D2; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000235:genetics / Q000502:physiology*; D011499:Protein Processing, Post-Translational / Q000187:drug effects* / Q000502:physiology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology*
chemical_list: D006360:Heat-Shock Proteins; D009363:Neoplasm Proteins; D000091283:Protein Kinase D2; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D010768:Phosphoserine; D015240:Phorbol 12,13-Dibutyrate; D009496:Neurotensin; D000841:Anisomycin; D011494:Protein Kinases; C089212:protein kinase D; D011493:Protein Kinase C; D048051:p38 Mitogen-Activated Protein Kinases