TY - JOUR
T1 - Conformational changes induced in voltage-gated calcium channel Cav1.2 by BayK 8644 or FPL64176 modify the kinetics of secretion independently of Ca 2+ influx
AU - Marom, Merav
AU - Hagalili, Yamit
AU - Sebag, Ariel
AU - Tzvier, Lior
AU - Atlas, Daphne
PY - 2010/3/5
Y1 - 2010/3/5
N2 - The role of the L-type calcium channel (Cav1.2) as a molecular switch that triggers secretion prior to Ca2+ transport has previously been demonstrated in bovine chromaffin cells and rat pancreatic beta cells. Here, we examined the effect of specific Cav1.2 allosteric modulators, BayK 8644 (BayK) and FPL64176 (FPL), on the kinetics of catecholamine release, as monitored by amperometry in single bovine chromaffin cells. We show that 2 μM BayK or 0.5 μM FPL accelerates the rate of catecholamine secretion to a similar extent in the presence either of the permeable Ca2+ and Ba2+ or the impermeable charge carrier La3+. These results suggest that structural rearrangements generated through the binding of BayK or FPL, by altering the channel activity, could affect depolarization-evoked secretion prior to cation transport. FPL also accelerated the rate of secretion mediated by a Ca2+-impermeable channel made by replacing the wild type α11.2 subunit was replaced with the mutant α 11.2/ L775P. Furthermore, BayK and FPL modified the kinetic parameters of the fusion pore formation, which represent the initial contact between the vesicle lumen and the extracellular medium. A direct link between the channel activity and evoked secretion lends additional support to the view that the voltage-gated Ca2+ channels act as a signaling molecular switch, triggering secretion upstream to ion transport into the cell.
AB - The role of the L-type calcium channel (Cav1.2) as a molecular switch that triggers secretion prior to Ca2+ transport has previously been demonstrated in bovine chromaffin cells and rat pancreatic beta cells. Here, we examined the effect of specific Cav1.2 allosteric modulators, BayK 8644 (BayK) and FPL64176 (FPL), on the kinetics of catecholamine release, as monitored by amperometry in single bovine chromaffin cells. We show that 2 μM BayK or 0.5 μM FPL accelerates the rate of catecholamine secretion to a similar extent in the presence either of the permeable Ca2+ and Ba2+ or the impermeable charge carrier La3+. These results suggest that structural rearrangements generated through the binding of BayK or FPL, by altering the channel activity, could affect depolarization-evoked secretion prior to cation transport. FPL also accelerated the rate of secretion mediated by a Ca2+-impermeable channel made by replacing the wild type α11.2 subunit was replaced with the mutant α 11.2/ L775P. Furthermore, BayK and FPL modified the kinetic parameters of the fusion pore formation, which represent the initial contact between the vesicle lumen and the extracellular medium. A direct link between the channel activity and evoked secretion lends additional support to the view that the voltage-gated Ca2+ channels act as a signaling molecular switch, triggering secretion upstream to ion transport into the cell.
UR - http://www.scopus.com/inward/record.url?scp=77951235869&partnerID=8YFLogxK
U2 - 10.1074/jbc.M109.059865
DO - 10.1074/jbc.M109.059865
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C2 - 20054004
AN - SCOPUS:77951235869
SN - 0021-9258
VL - 285
SP - 6996
EP - 7005
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 10
ER -