CD 39-associated high ATPase activity contribute to the loss of P 2 X 7-mediated calcium response in LCL cells.
The P 2 X 7 nucleotide receptor is an adenosine 5'-triphosphate (ATP)-gated ion channel, which induces cation channel opening imparting significant permeability to Ca(2+), and is widely expressed in cells of hematopoietic origin. Our previous report showed that P 2 X 7-mediated calcium response was absent in three Epstein-Barr virus (EBV)-positive and P 2 X 7 positive cell lines. In this report, we detected the cell surface ATPase activity, which contributes to the hydrolysis of extracellular ATP, and the expression of CD 39, which is the main source of ATPase on hematopoietic cells, in these cell lines. Then, we tried to restore the P 2 X 7-mediated calcium response in LCL-H and J 6-1 cells by either increasing the concentration of agonist or suppressing the ATPase activity by betagammaMeATP, a synthetic poorly metabolizable ATP analogue. The results showed that LCL-H and J 6-1 cells had higher levels of ATPase activity and CD 39 expression. The treatment of 300 microM betagammaMeATP efficiently inhibited the ATPase activity on LCL-H and J 6-1 cells. Both elevation of agonist concentration (10mM ATP or 1mM BzATP) and pretreatment with 300 microM betagammaMeATP followed by stimulation with normal concentration of agonists (1mM ATP or 0.1mM BzATP) could cause P 2 X 7-mediated calcium response in LCL-H but neither in J 6-1 cells. These results suggested that multiple mechanisms contributed to the loss of the P 2 X 7-mediated calcium response. CD 39-associated high ATPase activity contributed to the loss of the P 2 X 7-mediated calcium response in LCL-H cells, while additional mechanism(s) existed in J 6-1 cells.
Nie
Kun
K
State Key Laboratory for Experimental Hematology, Institute of Hematology, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Tianjin 300020, PR China.
Zheng
Guo-Guang
GG
Zhang
Xiu-Jun
XJ
Lin
Yong-Min
YM
Wang
Lin
L
Li
Ge
G
Song
Yu-Hua
YH
Wu
Ke-Fu
KF
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D015703:Antigens, CD / Q000096:biosynthesis / Q000378:metabolism*; D001081:Apyrase / Q000096:biosynthesis / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D018922:HL-60 Cells; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D020298:U937 Cells
D015703:Antigens, CD; C546468:P2RX7 protein, human; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D001081:Apyrase; C067869:CD39 antigen; D002118:Calcium