Involvement of Sodium in Early Phosphatidylserine Exposure and Phospholipid Scrambling Induced by P2X7 Purinoceptor Activation in Thymocytes

Extracellular ATP (ATP ec ), a possible effector in thymocyte selection, induces thymocyte death via purinoceptor activation. We show that ATP ec induced cell death by apoptosis, rather than lysis, and early phosphatidylserine (PS) exposure and phospholipid scrambling in a limited thymocyte populati...

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Bibliographic Details
Published in:The Journal of biological chemistry 2004-05, Vol.279 (21), p.21815-21823
Main Authors: Courageot, M-P, Lepine, S, Hours, M, Giraud, F, Sulpice, J-C
Format: Article
Language:English
Subjects:
Adenosine Triphosphate - chemistry
Adenosine Triphosphate - pharmacology
Animals
Apoptosis
Calcium - chemistry
Calcium - metabolism
Cations - metabolism
CD4 Antigens - biosynthesis
CD8 Antigens - biosynthesis
Cell Membrane - metabolism
Cell Nucleus - metabolism
Cytoplasm - metabolism
Cytosol - metabolism
Dose-Response Relationship, Drug
Ethidium - pharmacology
Flow Cytometry
Kinetics
Male
Mice
Mice, Inbred BALB C
Phosphatidylserines - chemistry
Phospholipids - metabolism
Propidium - pharmacology
Protein Structure, Tertiary
Receptors, Purinergic P2 - metabolism
Receptors, Purinergic P2X7
Sodium - chemistry
Sodium - metabolism
Temperature
Thymus Gland - cytology
Thymus Gland - metabolism
Time Factors
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Summary:Extracellular ATP (ATP ec ), a possible effector in thymocyte selection, induces thymocyte death via purinoceptor activation. We show that ATP ec induced cell death by apoptosis, rather than lysis, and early phosphatidylserine (PS) exposure and phospholipid scrambling in a limited thymocyte population (35–40%). PS externalization resulted from the activation of the cationic channel P2X7 (formerly P2Z) receptor and was triggered in all thymocyte subsets although to different proportions in each one. Phospholipid movement was dependent on ATP ec -induced Ca 2+ and/or Na + influx. At physiological external Na + concentration, without external Ca 2+ , PS was exposed in all ATP ec -responsive cells. In contrast, without external Na + , physiological external Ca 2+ concentration promoted a submaximal response. Altogether these data show that Na + influx plays a major role in the rapid PS exposure induced by P2X7 receptor activation in thymocytes.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M401426200