Ca2+-induced p38/SAPK signalling inhibited by the immunosuppressant cyclosporin A in human peripheral blood mononuclear cells.
To understand the effects of the immunosuppressant cyclosporin A (CsA) on Ca2+-mediated intracellular signalling pathways in human peripheral blood mononuclear cells (PBMCs), we investigated its effects on the activity profiles of mitogen-activated protein kinase (MAPK) cascades. PBMCs, or subpopulations thereof, were simultaneously stimulated with a phorbol ester and the calcium ionophore ionomycin, in the presence or absence of therapeutic concentrations of CsA. In these primary human cells, CsA significantly inhibited PMA/ionomycin-mediated and ionomycin-mediated activation of the MAPK kinase MKK6, as well as its downstream kinases SAPK2a (p38alpha) and MAPKAP-K2. PMA/ionomycin treatment also mediated activation of SAPK1 (JNKs) which was inhibited by CsA. Treatment with ionomycin alone also resulted in CsA-sensitive activation of SAPK1. With regard to transcription factors targeted by the Ca2+-induced MAPK signalling network, we found CsA to inhibit the ionomycin-mediated phosphorylation of ATF2 at Thr71. We identified the heterodimeric transcription factor ATF2/CREB as constitutively binding to the essential cAMP response element (CRE) site within the Ca2+-regulated DNA polymerase beta promoter and contributing to the activation of this promoter. Our data implicate ATF2 phosphorylation status as a nuclear sensor within PBMCs that monitors converging intracellular Ca2+-signalling pathways.
Kreideweiss
S
S
Medizinische Hochschule Hannover, Institut für Molekularbiologie, Hannover, Germany.
Ahlers
C
C
Nordheim
A
A
Rühlmann
A
A
D051698:Activating Transcription Factor 2; D001483:Base Sequence; D001665:Binding Sites; D019703:Calcineurin / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology*; D004247:DNA / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D015751:Genes, pol / Q000187:drug effects; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D015759:Ionomycin / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D048669:MAP Kinase Kinase 6; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2
D051698:Activating Transcription Factor 2; D019703:Calcineurin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D017362:Cyclic AMP Response Element-Binding Protein; D016572:Cyclosporine; D004247:DNA; D007166:Immunosuppressive Agents; D047908:Intracellular Signaling Peptides and Proteins; D015759:Ionomycin; D048031:JNK Mitogen-Activated Protein Kinases; D048669:MAP Kinase Kinase 6; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D014157:Transcription Factors; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C497105:ATF2 protein, human; C482566:MAP2K6 protein, human