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Imaging G Protein-coupled Receptor-mediated Chemotaxis and its Signaling Events in Neutrophil-like HL60 Cells
Published on: September 14, 2016
Multiple, PKA-dependent and PKA-independent, signals are involved in cAMP-induced PRL expression in the eosinophilic
Sarah Gerlo1, Peggy Verdood, Elisabeth L Hooghe-Peters
1Laboratory of Neuroendocrine Immunology, Department of Pharmacology, Free University of Brussels (VUB), Laarbeeklaan 103, B-1090 Brussels, Belgium. Sarah.Gerlo@vub.ac.be
Abstract:
Besides its pivotal role in reproduction, the polypeptide hormone prolactin (PRL) has been attributed an immunomodulatory function. Extrapituitary PRL expression is regulated differently from that in the pituitary, due to the use of an alternative promoter. In leukocytes, cAMP is an important regulator of PRL expression. We report that in the human eosinophilic cell line Eol-1, cAMP-induced PRL expression is partially abrogated by two protein kinase A (PKA) inhibitors (H89, PKI) and by the p38 inhibitor SB203580. Phosphorylation of p38 was PKA-independent and could be stimulated by a methylated cAMP analogue, which specifically activates the exchange factor directly activated by cAMP (EPAC). Furthermore, cAMP induced a PKA-dependent phosphorylation of cAMP-responsive element binding protein (CREB). We postulate that cAMP induces PRL expression via two different signalling pathways: a PKA-dependent pathway leading to the phosphorylation of CREB, and a PKA-independent pathway leading to the phosphorylation of p38.
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