Multiple cAMP-induced signaling cascades regulate prolactin expression in T cells.
Beside its pivotal role in reproduction, the pituitary hormone prolactin (PRL) has been attributed an immunomodulatory function. Here we report that cAMP is an important stimulator of PRL transcription in primary human T lymphocytes. Inhibition of both protein kinase A (PKA) and p38 MAPK partially abrogated cAMP-induced PRL expression. In addition, cAMP-induced phosphorylation of p38 was shown to occur independently of PKA and could be mimicked by a methylated cAMP analogue which specifically activates the recently discovered cAMP receptor EPAC (exchange protein directly activated by cAMP). Our findings suggest that cAMP induces PRL expression in T lymphocytes via cooperation of at least two different signaling pathways: a PKA-dependent pathway leading to the phosphorylation of cAMP response element-binding protein, and a PKA-independent pathway leading to p38 phosphorylation.
Gerlo
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S
Neuroendocrine Immunology Research Group, Department of Pharmacology, Free University of Brussels (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
Verdood
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P
Hooghe-Peters
E L
EL
Kooijman
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R
D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011388:Prolactin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics
D020662:Guanine Nucleotide Exchange Factors; C116122:RAPGEF3 protein, human; D012333:RNA, Messenger; D011388:Prolactin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases