title: 1alpha,25-dihydroxyvitamin D3 stimulates activator protein 1 DNA-binding activity by a phosphatidylinositol 3-kinase/Ras/MEK/extracellular signal regulated kinase 1/2 and c-Jun N-terminal kinase 1-dependent increase in c-Fos, Fra1, and c-Jun expression in human keratinocytes.
abstract: 1alpha,25-Dihydroxyvitamin D3 added to human keratinocytes increases differentiation through an activation of the transcription factor activator protein 1. We have previously reported that the 1alpha,25-dihydroxyvitamin D3-induced increase of activator protein 1 DNA binding activity is mediated by a protein kinase C-independent mechanism. The purpose of this study was to investigate further the mechanisms by which 1alpha,25-dihydroxyvitamin D3 modulates activator protein 1 DNA binding activity in cultured normal human keratinocytes. Western blotting experiments revealed that 1alpha,25-dihydroxyvitamin D3 caused a rapid and transient activation of the mitogen-activated protein kinases, extracellular signal regulated kinase 1/2 and c-Jun N-terminal kinase 1. 1alpha,25-Dihydroxyvitamin D3 also enhanced the expression of the activator protein 1 subunits, c-Fos, Fra1, and c-Jun as determined by northern and western blotting. The 1alpha,25-dihydroxyvitamin D3-induced activator protein 1 DNA binding activity was completely blocked by the MEK inhibitor PD 98059 indicating that the MEK/extracellular signal regulated kinase pathway is involved in the activation of activator protein 1. Transfection experiments showed that 1alpha,25-dihydroxyvitamin D3 also increased the activator protein 1-dependent transactivation, which was completely blocked by expression of a dominant negative Ras, suggesting that the 1alpha,25-dihydroxyvitamin D3-induced activator protein 1 activity involves Ras-dependent signaling. Furthermore, preincubation of the keratinocytes with the specific phosphatidylinositol 3-kinase inhibitors, Wortmannin and LY294002, demonstrated that the 1alpha,25-dihydroxyvitamin D3-induced activation of extracellular signal regulated kinase 1/2 and c-Jun N-terminal kinase 1 required phosphatidylinositol 3-kinase activity. Finally, preincubation of keratinocytes with a polyclonal antibody against the membrane receptor annexin II, blocked the 1alpha,25-dihydroxyvitamin D3-induced activation of extracellular signal regulated kinase 1/2 and c-Jun N-terminal kinase 1. Taken together, our results indicate that 1alpha,25-dihydroxyvitamin D3, via binding to the membrane receptor annexin II, induces activation of the phos-phatidylinositol 3-kinase/Ras/MEK/extracellular signal regulated kinase 1/2 and c-Jun N-terminal kinase 1 signal transduction pathway resulting in increased expression of c-Fos, Fra1, and c-Jun, and subsequently increased activator protein 1 DNA binding activity and gene transcription.
authors.affiliation: Department of Dermatology, Marselisborg Hospital, University of Aarhus, Denmark. clausoglotte@hotmail.com
authors.forename: Claus
authors.initials: C
authors.lastname: Johansen
authors.forename: Knud
authors.initials: K
authors.lastname: Kragballe
authors.forename: Jeanette
authors.initials: J
authors.lastname: Henningsen
authors.forename: Majken
authors.initials: M
authors.lastname: Westergaard
authors.forename: Karsten
authors.initials: K
authors.lastname: Kristiansen
authors.forename: Lars
authors.initials: L
authors.lastname: Iversen
mesh_terms: D000328:Adult; D017306:Annexin A2 / Q000276:immunology / Q000378:metabolism; D000906:Antibodies / Q000494:pharmacology; D002117:Calcitriol / Q000494:pharmacology*; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D002478:Cells, Cultured; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D048728:MAP Kinase Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism; D000099169:Fos-Related Antigen 1
chemical_list: D017306:Annexin A2; D000906:Antibodies; D002117:Calcitriol; D002120:Calcium Channel Agonists; D048031:JNK Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D018631:ras Proteins; D000099169:Fos-Related Antigen 1; C482576:MAP3K1 protein, human