Ca(2+) and p38 MAP kinase regulate mAChR-mediated c-Fos expression in avian exocrine cells.
Muscarinic acetylcholine receptors (mAChRs) in exocrine tissue from the avian nasal salt gland are coupled to phospholipase C and generate inositol phosphate and Ca(2+) signals upon activation. An early effect of receptor activation in the secretory cells is a transient accumulation of c-Fos protein. In cooperation with constitutively expressed Jun, Fos presumably serves as a transcription factor altering gene expression during cell growth and differentiation processes in the gland associated with adaptation to osmotic stress in animals. Nothing is known, however, about the mAChR-dependent signaling pathways leading to Fos expression in these cells. By incubation of isolated nasal gland tissue in short-term culture with activators or inhibitors of signaling pathways and quantitative Western blot analysis of Fos abundance, we have now identified the sustained elevation of the intracellular Ca(2+) concentration and the activation of the p38 mitogen-activated protein (MAP) kinase as intermediate signaling elements for the regulation of c-Fos by muscarinic receptor activation. It is suggested that p38 MAP kinase, rather than exclusively mediating stress responses, is involved in the regulation of cellular growth and differentiation controlled by G protein-coupled receptors.
Hildebrandt
J P
JP
Physiologisches Institut, Medizinische Fakultät, Universität des Saarlandes, D-66421 Homburg/Saar. jph@mail.uni-greifswald.de
Prowald
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D046508:Culture Techniques; D004372:Ducks; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012491:Salt Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases
D016760:Proto-Oncogene Proteins c-fos; D011956:Receptors, Cell Surface; D011976:Receptors, Muscarinic; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D002118:Calcium