Abstract
Deactivation of brain macrophages (microglia) by transforming growth factor-β (TGF-β) is characterized by enhanced Kv1.3 K+ channel expression. The intracellular mechanisms by which TGF-β causes K+ channel upregulation in microglia have remained unclear. We show here that the protein kinase inhibitor H7 abolishes TGF-β-induced increases in delayed rectifier K+ current density. However, this effect cannot be related to inhibition of protein kinase C (PKC) or protein kinase A (PKA) activity, because specific PKC and PKA inhibitors did not exhibit effects identical to H7. TGF-β-induced Kv1.3 channel expression was also unaffected by inhibitors of tyrosine kinase, Ca2+/calmodulin kinase II and mitogen-activated protein (MAP) kinase ERK. In contrast, delayed rectifier K+ current density was larger in TGF-β-stimulated cells pretreated with the p38 MAP kinase inhibitor SB203580 or the phosphatidylinositol 3-OH (PI3) kinase inhibitor wortmannin, suggesting that both p38 MAP kinase and PI3 kinase regulate negatively the upregulation of Kv1.3 K+ channels in TGF-β-treated microglial cells.
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References
Attisano L, Wrana JL (2002) Signal transduction by the TGF-β superfamily. Science 296:1646–1647
Deutsch C, Krause D, Lee SC (1986) Voltage-gated potassium conductance in human T lymphocytes stimulated with phorbol ester. J Physiol (Lond) 372:405–423
Gamper N, Fillon S, Huber SM, Feng Y, Kobayashi T, Cohen P, Lang F (2002) IGF-1 up-regulates K+ channels via PI3-kinase, PDK1 and SGK1. Pflugers Arch 443:625–634
Kumahara E, Ebihara T, Saffen D (1999) Protein kinase inhibitor H7 blocks the induction of immediate-early genes zif268 and c-fos by a mechanism unrelated to inhibition of protein kinase C but possibly related to inhibition of phosphorylation of RNA polymerase II. J Biol Chem 274:10430–10438
Küst BM, Biber K, van Calker D, Gebicke-Haerter PJ (1999) Regulation of K+ channel mRNA expression by stimulation of adenosine A2a-receptors in cultured rat microglia. Glia 25:120–130
Ohtsuki M, Massagué J (1992) Evidence for the involvement of protein kinase activity in transforming growth factor-β signal transduction. Mol Cell Biol 12:261–265
Schilling T, Quandt FN, Cherny VV, Zhou W, Heinemann U, DeCoursey TE, Eder C (2000) Upregulation of Kv1.3 K+ channels in microglia deactivated by TGF-β. Am J Physiol 279:C1123–C1134
Waldegger S, Klingel K, Barth P, Sauter M, Lanzendörfer ML, Kandolf R, Lang F (1999) h-sgk serine-threonine protein kinase gene as transcriptional target of transforming growth factor β in human intestine. Gastroenterology 116:1081–1088
Acknowledgements
This work was supported by the Deutsche Forschungsgemeinschaft grant SFB 507/C7 and a Heisenberg fellowship (both to C.E.). The authors wish to thank Sieglinde Latta for the preparation of cell cultures.
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Schilling, T., Eder, C. Effects of kinase inhibitors on TGF-β induced upregulation of Kv1.3 K+ channels in brain macrophages. Pflugers Arch - Eur J Physiol 447, 312–315 (2003). https://doi.org/10.1007/s00424-003-1155-3
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DOI: https://doi.org/10.1007/s00424-003-1155-3