Lysophosphatidic acid-induced c-fos up-regulation involves cyclic AMP response element-binding protein activated by mitogen- and stress-activated protein kinase-1.
Lysophosphatidic acid (LPA) is a lipid growth factor that exerts diverse biological effects through its cognate receptor-mediated signaling cascades. Recently, we reported that LPA stimulates cAMP response element-binding protein (CREB) through mitogen- and stress-activated protein kinase-1 (MSK1). Previously, LPA has been shown to stimulate c-fos mRNA expression in Rat-2 fibroblast cells via a serum response element binding protein (SRF). However, involvement of CREB in LPA-stimulated c-fos gene expression is not elucidated yet. To investigate the CREB-mediated c-fos activation by LPA, various c-fos promoter-reporter constructs containing wild-type and mutated SRE and CRE were tested for their inducibility by LPA in transient transfection assays. LPA-stimulated c-fos promoter activation was markedly decreased when SRE and CRE were mutated. A dominant negative CREB significantly down-regulated the LPA-stimulated c-fos promoter activation. Chromatin immunoprecipitation assay revealed that LPA induced an increased binding of phosphorylated CREB and CREB-binding protein (CBP) to the CRE region of the endogenous c-fos promoter. Immunoblot analyses with various pharmacological inhibitors further showed that LPA induces up-regulation of c-fos mRNA level by activation of ERK, p38 MAPK, and MSK1. Taken together, our results suggest that CREB plays an important role in up-regulation of c-fos mRNA level in LPA-stimulated Rat-2 fibroblast cells.
Lee
Chang-Wook
CW
Department of Molecular Biology, Helen L. Dorris Child and Adolescent Neuropsychiatric Disorder Institute, The Scripps Research Institute, La Jolla, California 92037, USA.
Kim
Nam-Ho
NH
Choi
Ho-Kyew
HK
Sun
Yuanjie
Y
Nam
Ju-Suk
JS
Rhee
Hae Jin
HJ
Chun
Jerold
J
Huh
Sung-Oh
SO
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D020935:MAP Kinase Signaling System; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism*; D008954:Models, Biological; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D051381:Rats; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D017362:Cyclic AMP Response Element-Binding Protein; D008246:Lysophospholipids; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D000242:Cyclic AMP; D048055:Mitogen-Activated Protein Kinase 8; D048051:p38 Mitogen-Activated Protein Kinases; C032881:lysophosphatidic acid