title: Leukotriene D4 mediates survival and proliferation via separate but parallel pathways in the human intestinal epithelial cell line Int 407.
abstract: We demonstrated previously that leukotriene D4 (LTD4) regulates proliferation of intestinal epithelial cells through a CysLT receptor by protein kinase C (PKC)epsilon-dependent stimulation of the mitogen-activated protein kinase ERK1/2. Our current study provides the first evidence that LTD4 can activate 90-kDa ribosomal S6 kinase (p90RSK) and cAMP-responsive element-binding protein (CREB) via pertussis-toxin-sensitive Gi protein pathways. Transfection and inhibitor experiments revealed that activation of p90RSK, but not CREB, is a PKCepsilon/Raf-1/ERK1/2-dependent process. LTD4-mediated CREB activation was not affected by expression of kinase-dead p90RSK but was abolished by transfection with the regulatory domain of PKCalpha (a specific dominant-inhibitor of PKCalpha). Kinase-negative mutants of p90RSK and CREB (K-p90RSK and K-CREB) blocked the LTD4-induced increase in cell number and DNA synthesis (thymidine incorporation). Compatible with these results, flow cytometry showed that LTD4 caused transition from the G0/G1 to the S+G2/M cell cycle phase, indicating increased proliferation. Similar treatment of cells transfected with K-p90RSK resulted in cell cycle arrest in the G0/G1 phase, consistent with a role of p90RSK in LTD4-induced proliferation. On the other hand, expression of K-CREB caused a substantial buildup in the sub-G0/G1 phase, suggesting a role for CREB in mediating LTD4-mediated survival in intestinal epithelial cells. Our results show that LTD4 regulates proliferation and survival via distinct intracellular signaling pathways in intestinal epithelial cells.
authors.affiliation: Division of Experimental Pathology, Department of Laboratory Medicine, Lund University, University Hospital Malmö, Malmö SE-205 02, Sweden.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Paruchuri
authors.forename: Anita
authors.initials: A
authors.lastname: Sjölander
mesh_terms: D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D002470:Cell Survival; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D005799:Genes, Dominant; D006801:Humans; D007422:Intestines / Q000166:cytology*; D017998:Leukotriene D4 / Q000378:metabolism / Q000502:physiology*; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000378:metabolism; D051744:Protein Kinase C-epsilon; D017434:Protein Structure, Tertiary; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D015398:Signal Transduction; D013936:Thymidine / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D018076:DNA, Complementary; D020033:Protein Isoforms; D017998:Leukotriene D4; D037342:Pertussis Toxin; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D013936:Thymidine