P2Z purinoceptor, a special receptor for apoptosis induced by ATP in human leukemic lymphocytes.
OBJECTIVE
To investigate the role of purinergic P2Z receptors for apoptosis of human leukemic lymphocytes mediated by extracellular adenosine triphosphate (ATP).


METHODS
A total of 13 B-chronic lymphocytic leukemia (CLL) patients were studied. Exposure of leukemic lymphocytes with (n = 8) or without (n = 5) P2Z receptors to ATP, benzoylbenzoic-ATP (BzATP), 2-methylthio-ATP (2MeSATP), adenosine-5' [gamma-thio] triphosphate (ATP-gamma S), and other nucleosides for 8 h in vitro. Apoptosis was detected by electron microscopy (EM), agarose gel electrophoresis, and the quantitative assay-TdT assay.


RESULTS
Apoptosis was detected only in leukemic lymphocytes with P2Z receptors. Using a quantitative assay, ATP-induced DNA strand breaks were found to occur specifically with BzATP, ATP and 2MeSATP, but not for analogue ATP-gamma S nor other nucleosides. Meanwhile, ATP-induced DNA fragmentation was fully blocked by pretreatment with oxidized ATP (OxATP), a compound recently shown to block P2Z receptors. Also, it is shown that the Ca2+/calmodulin complex plays a role in the regulation of the apoptosis induced by ATP on CLL cells, because an antagonist of this complex, 1-[N, O-bis (5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN-62) was found to inhibit the ATP-induced apoptosis. Furthermore, choline, an inhibitor of phospholipase D (PLD), is first shown to partially inhibit ATP-induced apoptosis.


CONCLUSIONS
These data indicate that P2Z receptors on lymphocytes play an important role in the apoptosis induced by ATP in vitro.
Peng
L
L
Department of Laboratory Medicine, First Hospital, West China University of Medical Sciences, Chengdu 610041, China.
Bradley
C J
CJ
Wiley
J S
JS
D000255:Adenosine Triphosphate / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002469:Cell Separation; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism / Q000473:pathology*; D008214:Lymphocytes / Q000473:pathology*; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D058486:Receptors, Purinergic P2X7
C546468:P2RX7 protein, human; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate