Phospholipase C-delta1 is activated by capacitative calcium entry that follows phospholipase C-beta activation upon bradykinin stimulation.
To characterize the regulatory mechanism of phospholipase C-delta1 (PLC-delta1) in the bradykinin (BK) receptor-mediated signaling pathway, we used a clone of PC12 cells, which stably overexpress PLC-delta1 (PC12-D1). Stimulation with BK induced a significantly higher Ca(2+) elevation and inositol 1,4,5-trisphosphate (IP(3)) production with a much lower half-maximal effective concentration (EC(50)) of BK in PC12-D1 cells than in wild type (PC12-W) or vector-transfected (PC12-V) cells. However, BK-induced intracellular Ca(2+) release and IP(3) generation was similar between PC12-V and PC12-D1 cells in the absence of extracellular Ca(2+), suggesting that the availability of extracellular Ca(2+) is essential to the activation of PLC-delta1. When PC12-D1 cells were treated with agents that induce Ca(2+) influx, more IP(3) was produced, suggesting that the Ca(2+) entry induces IP(3) production in PC12-D1 cells. Furthermore, the additional IP(3) production after BK-induced capacitative calcium entry was detected in PC12-D1 cells, suggesting that PLC-delta1 is mainly activated by capacitative calcium entry. When cells were stimulated with BK in the presence of extracellular Ca(2+), [(3)H]norepinephrine secretion was much greater from PC12-D1 cells than from PC12-V cells. Our results suggest that PLC-delta1 is activated by capacitative calcium entry following the activation of PLC-beta, additively inducing IP(3) production and Ca(2+) rise in BK-stimulated PC12 cells.
Kim
Y H
YH
Department of Life Science, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea.
Park
T J
TJ
Lee
Y H
YH
Baek
K J
KJ
Suh
P G
PG
Ryu
S H
SH
Kim
K T
KT
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D007527:Isoenzymes / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D016716:PC12 Cells; D054799:Phospholipase C beta; D054803:Phospholipase C delta; D051381:Rats; D010738:Type C Phospholipases / Q000378:metabolism*
D007527:Isoenzymes; D015544:Inositol 1,4,5-Trisphosphate; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D054803:Phospholipase C delta; C518026:Plcd1 protein, rat; D019204:GTP-Binding Proteins; D001920:Bradykinin; D002118:Calcium; D009638:Norepinephrine