TY - JOUR
T1 - Maitotoxin and P2Z/P2X7 purinergic receptor stimulation activate a common cytolytic pore
AU - Schilling, William P.
AU - Wasylyna, Tanya
AU - Dubyak, George R.
AU - Humphreys, Benjamin D.
AU - Sinkins, William G.
PY - 1999
Y1 - 1999
N2 - The effects of maitotoxin (MTX) on plasmalemma permeability are similar to those caused by stimulation of P2Z/P2X7 ionotropic receptors, suggesting that 1) MTX directly activates P2Z/P2X7 receptors or 2) MTX and P2Z/P2X7 receptor stimulation activate a common cytolytic pore. To distinguish between these two possibilities, the effect of MTX was examined in 1) THP-1 monocytic cells before and after treatment with lipopolysaccharide and interferon-γ, a maneuver known to upregulate P2Z/P2X7 receptor, 2) wild-type HEK cells and HEK cells stably expressing the P2Z/P2X7 receptor, and 3) BW5147.3 lymphoma cells, a cell line that expresses functional P2Z/P2X7 channels that are poorly linked to pore formation. In control THP-1 monocytes, addition of MTX produced a biphasic increase in the cytosolic free Ca2+ concentration ([Ca2+](i)); the initial increase reflects MTX-induced Ca2+ influx, whereas the second phase correlates in time with the appearance of large pores and the uptake of ethidium. MTX produced comparable increases in [Ca2+](i) and ethidium uptake in THP-1 monocytes overexpressing the P2Z/P2X7 receptor. In both wild-type HEK and HEK cells stably expressing the P2Z/P2X7 receptor, MTX-induced increases in [Ca2+](i) and ethidium uptake were virtually identical. The response of BW5147.3 cells to concentrations of MTX that produced large increases in [Ca2+](i) had no effect on ethidium uptake. In both THP-1 and HEK cells, MTX- and Bz-ATP-induced pores activate with similar kinetics and exhibit similar size exclusion. Last, MTX-induced pore formation, but not channel activation, is greatly attenuated by reducing the temperature to 22°C, a characteristic shared by the P2Z/P2X7-induced pore. Together, the results demonstrate that, although MTX activates channels that are distinct from those activated by P2Z/P2X7 receptor stimulation, the cytolytic/oncotic pores activated by MTX- and Bz-ATP are indistinguishable.
AB - The effects of maitotoxin (MTX) on plasmalemma permeability are similar to those caused by stimulation of P2Z/P2X7 ionotropic receptors, suggesting that 1) MTX directly activates P2Z/P2X7 receptors or 2) MTX and P2Z/P2X7 receptor stimulation activate a common cytolytic pore. To distinguish between these two possibilities, the effect of MTX was examined in 1) THP-1 monocytic cells before and after treatment with lipopolysaccharide and interferon-γ, a maneuver known to upregulate P2Z/P2X7 receptor, 2) wild-type HEK cells and HEK cells stably expressing the P2Z/P2X7 receptor, and 3) BW5147.3 lymphoma cells, a cell line that expresses functional P2Z/P2X7 channels that are poorly linked to pore formation. In control THP-1 monocytes, addition of MTX produced a biphasic increase in the cytosolic free Ca2+ concentration ([Ca2+](i)); the initial increase reflects MTX-induced Ca2+ influx, whereas the second phase correlates in time with the appearance of large pores and the uptake of ethidium. MTX produced comparable increases in [Ca2+](i) and ethidium uptake in THP-1 monocytes overexpressing the P2Z/P2X7 receptor. In both wild-type HEK and HEK cells stably expressing the P2Z/P2X7 receptor, MTX-induced increases in [Ca2+](i) and ethidium uptake were virtually identical. The response of BW5147.3 cells to concentrations of MTX that produced large increases in [Ca2+](i) had no effect on ethidium uptake. In both THP-1 and HEK cells, MTX- and Bz-ATP-induced pores activate with similar kinetics and exhibit similar size exclusion. Last, MTX-induced pore formation, but not channel activation, is greatly attenuated by reducing the temperature to 22°C, a characteristic shared by the P2Z/P2X7-induced pore. Together, the results demonstrate that, although MTX activates channels that are distinct from those activated by P2Z/P2X7 receptor stimulation, the cytolytic/oncotic pores activated by MTX- and Bz-ATP are indistinguishable.
KW - HEK cells
KW - Heterologous expression
KW - Oncosis
KW - THP-1 monocytes
KW - Vital dyes
UR - http://www.scopus.com/inward/record.url?scp=0032718108&partnerID=8YFLogxK
U2 - 10.1152/ajpcell.1999.277.4.c766
DO - 10.1152/ajpcell.1999.277.4.c766
M3 - Article
C2 - 10516107
AN - SCOPUS:0032718108
SN - 0363-6143
VL - 277
SP - C766-C776
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
IS - 4 46-4
ER -