Extracellular ATP induces oscillations of intracellular Ca2+ and membrane potential and promotes transcription of IL-6 in macrophages.
The effects of low concentrations of extracellular ATP on cytosolic Ca(2+), membrane potential, and transcription of IL-6 were studied in monocyte-derived human macrophages. During inflammation or infection many cells secrete ATP. We show here that application of 10 microM ATP or 10 microM UTP induces oscillations in cytosolic Ca(2+) with a frequency of approximately 12 min(-1) and oscillations in membrane potential. RT-PCR analysis showed expression of P2Y(1), P2Y(2), P2Y(11), P2X(1), P2X(4), and P2X(7) receptors, large-conductance (KCNMA1 and KCNMB1-4), and intermediate-conductance (KCNN4) Ca(2+)-activated K(+) channels. The Ca(2+)oscillations were unchanged after removal of extracellular Ca(2+), indicating that they were mainly due to movements of Ca(2+) between intracellular compartments. Comparison of the effects of different nucleotides suggests that the Ca(2+) oscillations were elicited by activation of P2Y(2) receptors coupled to phospholipase C. Patch-clamp experiments showed that ATP induced a transient depolarization, probably mediated by activation of P2X(4) receptors, followed by membrane potential oscillations due to opening of Ca(2+)-activated K(+) channels. We also found that 10 microM ATP gamma S increased transcription of IL-6 approximately 40-fold within 2 h. This effect was abolished by blockade of P2Y receptors with 100 microM suramin. Our results suggest that ATP released from inflamed, damaged, or metabolically impaired cells represents a "danger signal" that plays a major role in activating the innate immune system.
Hanley
Peter J
PJ
Institute of Physiology, Marburg University, Deutschhausstrasse 2, 35037 Marburg, Germany.
Musset
Boris
B
Renigunta
Vijay
V
Limberg
Sven H
SH
Dalpke
Alexander H
AH
Sus
Rainer
R
Heeg
Klaus M
KM
Preisig-Müller
Regina
R
Daut
Jürgen
J
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects*; D008969:Molecular Sequence Data; D009991:Oscillometry; D018408:Patch-Clamp Techniques; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology; D012964:Sodium / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*
D015850:Interleukin-6; C494841:KCNMA1 protein, human; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D012964:Sodium; D002118:Calcium