title: Leukotriene D(4) activates MAPK through a Ras-independent but PKCepsilon-dependent pathway in intestinal epithelial cells.
abstract: We have recently shown that leukotriene D(4) (LTD(4)) increases cell survival in intestinal epithelial cells. Here we report and explore the complementary finding that LTD(4) also enhances proliferation in these cells. This proliferative response was approximately half of that induced by epidermal growth factor (EGF) and its required activation of protein kinase C (PKC), Ras and the mitogen-activated protein kinase (MAPK) Erk-1/2. EGF also activated Erk-1/2 in these cells; however the EGF-receptor inhibitor PD153035 did not affect the LTD(4)-induced activation of Erk-1/2. In addition, LTD(4) did not induce phosphorylation of the EGF receptor, nor did pertussis toxin (PTX) block EGF-induced activation of Erk-1/2, thus refuting a possible crosstalk between the receptors. Furthermore, LTD(4)-induced, but not EGF-induced, activation of Erk-1/2 was sensitive to PTX, PKC inhibitors and downregulation of PKCepsilon. A definite role for PKCepsilon in LTD(4)-induced stimulation of Erk-1/2 was documented by the inability of LTD(4) to activate Erk-1/2 in cells transfected with either the regulatory domain of PKCepsilon (an isoform specific dominant-negative inhibitor) or a kinase-dead PKCepsilon. Although Ras and Raf-1 were both transiently activated by LTD(4), only Raf-1 activation was abolished by abrogation of the PKC signal. Furthermore, the LTD(4)-induced activation of Erk-1/2 was unaffected by transfection with dominant-negative N17 Ras but blocked by transfection with kinase-dead Raf-1. Consequently, LTD(4) regulates the proliferative response by a distinct Ras-independent, PKCepsilon-dependent activation of Erk-1/2 and a parallel Ras-dependent signaling pathway.
authors.affiliation: Division of Experimental Pathology, Department of Laboratory Medicine, Lund University, University Hospital Malmö, SE-205 02 Malmö, Sweden.
authors.forename: Sailaja
authors.initials: S
authors.lastname: Paruchuri
authors.forename: Bengt
authors.initials: B
authors.lastname: Hallberg
authors.forename: Maria
authors.initials: M
authors.lastname: Juhas
authors.forename: Christer
authors.initials: C
authors.lastname: Larsson
authors.forename: Anita
authors.initials: A
authors.lastname: Sjölander
mesh_terms: D002277:Carcinoma / Q000201:enzymology / Q000503:physiopathology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000201:enzymology / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000166:cytology / Q000201:enzymology*; D007414:Intestinal Neoplasms / Q000201:enzymology / Q000503:physiopathology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017998:Leukotriene D4 / Q000378:metabolism* / Q000494:pharmacology; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D020033:Protein Isoforms / Q000187:drug effects / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000187:drug effects / Q000378:metabolism; D018631:ras Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D020033:Protein Isoforms; D017998:Leukotriene D4; D066246:ErbB Receptors; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D018631:ras Proteins