Pfeilschifter J, Huwiler A
Department of Pharmacology, University of Basel, Switzerland.
FEBS Lett. 1993 Oct 4;331(3):267-71. doi: 10.1016/0014-5793(93)80350-4.
The role of Ca2+ and protein kinase C (PKC) in the regulation of phosphatidylcholine-hydrolyzing phospholipase D (PLD) was investigated in angiotensin II-stimulated mesangial cells. Elevation of cytosolic free Ca2+ by the calcium ionophore, A23187, or the Ca(2+)-ATPase inhibitor, thapsigargin, slightly increased PLD-stimulated phosphatidylethanol formation. However, chelation of cytosolic Ca2+ with high concentrations of quin 2 did not attenuate angiotensin II-induced phosphatidylethanol production, thus suggesting that Ca2+ is not crucially involved in agonist-stimulated PLD activation. Stimulation of PKC by phorbol esters increased PLD activity in mesangial cells. Down-regulation of PKC-alpha and -delta isoenzymes by 8 h phorbol ester treatment still resulted in full PLD activation. In contrast, a 24 h treatment of mesangial cells with phorbol ester, a regimen that also causes depletion of PKC-epsilon, abolished angiotensin II-evoked phosphatidylethanol formation. In addition, the selective PKC inhibitor, calphostin C, attenuated hormone-induced PLD activity. In summary, these data suggest that angiotensin II stimulation of phospholipase D appears to involve the PKC-epsilon isoenzyme, activated by DAG derived from phosphoinositide hydrolysis.
在血管紧张素II刺激的系膜细胞中，研究了Ca2+和蛋白激酶C（PKC）在调节磷脂酰胆碱水解磷脂酶D（PLD）中的作用。钙离子载体A23187或Ca(2+)-ATP酶抑制剂毒胡萝卜素使胞质游离Ca2+升高，可轻微增加PLD刺激的磷脂酰乙醇形成。然而，高浓度的喹啉2螯合胞质Ca2+并未减弱血管紧张素II诱导的磷脂酰乙醇生成，因此表明Ca2+并非激动剂刺激的PLD激活所必需。佛波酯刺激PKC可增加系膜细胞中的PLD活性。用佛波酯处理8小时使PKC-α和-δ同工酶下调，PLD仍可完全激活。相反，用佛波酯处理系膜细胞24小时（此方案也会导致PKC-ε耗竭），则消除了血管紧张素II诱发的磷脂酰乙醇形成。此外，选择性PKC抑制剂钙磷蛋白C减弱了激素诱导的PLD活性。总之，这些数据表明血管紧张素II对磷脂酶D的刺激似乎涉及由磷酸肌醇水解产生的二酰甘油激活的PKC-ε同工酶。
