Probenecid blocks human P2X7 receptor-induced dye uptake via a pannexin-1 independent mechanism

P2X7 is a ligand-gated ion channel which is activated by ATP and displays secondary permeability characteristics. The mechanism of development of the secondary permeability pathway is currently unclear, although a role for the hemichannel protein pannexin-1 has been suggested. In this study we inves...

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Published in:	PloS one 2014-03, Vol.9 (3), p.e93058
Main Authors:	Bhaskaracharya, Archana, Dao-Ung, Phuong, Jalilian, Iman, Spildrejorde, Mari, Skarratt, Kristen K, Fuller, Stephen J, Sluyter, Ronald, Stokes, Leanne
Format:	Article
Language:	eng
Subjects:	Adenosine Triphosphate - physiology Apoptosis Arthritis ATP Biological Transport, Active Biology and Life Sciences Calcium Calcium Signaling CD14 antigen Connexins - metabolism Defects Dyes Ethidium - metabolism Fluorescent Dyes - metabolism HEK293 Cells Human behavior Humans IL-1β Inhibition Inhibitory Concentration 50 Interleukin-1beta - secretion Ion channels Isoquinolines - metabolism Lipopolysaccharides - physiology Medical research Medical schools Medicine and Health Sciences Monocytes Monocytes - immunology Monocytes - metabolism Nerve Tissue Proteins - metabolism Peptides Permeability Pharmacology Probenecid Probenecid - pharmacology Proteins Purinergic P2X Receptor Antagonists - pharmacology Receptors, Purinergic P2X7 - metabolism Rheumatism Rodents Studies Surface active agents Uric acid
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Summary:	P2X7 is a ligand-gated ion channel which is activated by ATP and displays secondary permeability characteristics. The mechanism of development of the secondary permeability pathway is currently unclear, although a role for the hemichannel protein pannexin-1 has been suggested. In this study we investigated the role of pannexin-1 in P2X7-induced dye uptake and ATP-induced IL-1β secretion from human monocytes. We found no pharmacological evidence for involvement of pannexin-1 in P2X7-mediated dye uptake in transfected HEK-293 cells with no inhibition seen for carbenoxolone and the pannexin-1 mimetic inhibitory peptide, 10Panx1. However, we found that probenecid inhibited P2X7-induced cationic and anionic dye uptake in stably transfected human P2X7 HEK-293 cells. An IC50 value of 203 μM was calculated for blockade of ATP-induced responses at human P2X7. Probenecid also reduced dye uptake and IL-1β secretion from human CD14+ monocytes whereas carbenoxolone and 10Panx1 showed no inhibitory effect. Patch clamp and calcium indicator experiments revealed that probenecid directly blocks the human P2X7 receptor.
ISSN:	1932-6203 1932-6203