Khouja A, Jones C T
Laboratory of Cellular and Developmental Physiology, University of Oxford, John Radcliffe Hospital, UK.
J Dev Physiol. 1993 Jan;19(1):1-7.
The effects of protein kinase C activation on phospholipase A2 and phospholipase C activity in permeabilised cultured myometrial cells from guinea pig uterus have been studied. Phospholipase A2 activity was followed by measurement of [3H]arachidonic acid release from [3H]arachidonic acid-prelabelled membrane lipids. [3H]Arachidonic acid release was stimulated by Ca2+ at 1-10 microM and by GTP gamma S at 1 microM to 1 mM in the presence of 10 microM Ca2+. The activation by calcium was enhanced 89.5 +/- 12.7% (P < 0.01) in the presence of 1 microM phorbol 12-myristate 13-acetate (PMA) and that by 1 microM GTP gamma S by 65.4 +/- 4.4% (P < 0.001). The PMA enhancement of arachidonic acid release was completely blocked by 3 microM staurosporine. Phospholipase C activation was followed by measurement of [3H]inositol polyphosphate production from [3H]inositol-prelabelled membrane lipids. This was stimulated by Ca2+ at 0.1 and 10 microM and by 1 and 50 microM GTP gamma S. PMA at 1 microM caused a consistent reduction in the extent of Ca2+ and GTP gamma S-stimulated inositol polyphosphate production and 3 microM reversed the inhibitory action of PMA. The data are consistent with arachidonic acid release in permeabilised myometrial cells from guinea pigs reflecting in large part phospholipase A2 activation and with that pathway being stimulated by protein kinase C activation. They are also consistent with protein kinase C activation causing reduction in phospholipase C pathways in uterine myocytes, at least as measured by inositol polyphosphate release.
研究了蛋白激酶C激活对豚鼠子宫透化培养的子宫肌层细胞中磷脂酶A2和磷脂酶C活性的影响。通过测量从[3H]花生四烯酸预标记的膜脂中释放的[3H]花生四烯酸来跟踪磷脂酶A2活性。在10μM Ca2+存在的情况下，1-10μM的Ca2+和1μM至1 mM的GTPγS刺激了[3H]花生四烯酸的释放。在1μM佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）存在的情况下，钙激活增强了89.5±12.7%（P<0.01），而1μM GTPγS激活增强了65.4±4.4%（P<0.001）。3μM星形孢菌素完全阻断了PMA对花生四烯酸释放的增强作用。通过测量从[3H]肌醇预标记的膜脂中产生的[3H]肌醇多磷酸来跟踪磷脂酶C的激活。这受到0.1和10μM的Ca2+以及1和50μM的GTPγS的刺激。1μM的PMA导致Ca2+和GTPγS刺激的肌醇多磷酸产生程度持续降低，而3μM则逆转了PMA的抑制作用。这些数据与豚鼠透化子宫肌层细胞中花生四烯酸的释放很大程度上反映磷脂酶A2的激活一致，并且该途径受到蛋白激酶C激活的刺激。它们也与蛋白激酶C激活导致子宫肌细胞中磷脂酶C途径减少一致，至少通过肌醇多磷酸释放来衡量是这样。
