Chmura S J, Nodzenski E, Crane M A, Virudachalam S, Hallahan D E, Weichselbaum R R, Quintans J
Department of Pathology, University of Chicago, Illinois, USA.
Adv Exp Med Biol. 1996;406:39-55. doi: 10.1007/978-1-4899-0274-0_5.
WEHI-231, a murine B-cell lymphoma, readily undergoes programmed cell death following surface immunoglobulin (Ig) cross-linking [1]. Ceramide has been shown to induce apoptosis in WEHI-231 following its exposure to anti-lg antibodies, dexamethasone, and irradiation [2]. Recently, Haimovitz-Friedman et al. have demonstrated in endothelial cells that PMA not only prevented ceramide mediated apoptosis, but inhibited the generation of ceramide following irradiation [3]. In this paper we use highly specific PKC inhibitors to explore the connection between PKC activity, ceramide signaling and apoptosis. Both chelerythrine chloride and calphostin C triggered rapid apoptosis in WEHI-231 and acted in synergy with exogenous ceramide to induce apoptosis. Detailed studies of chelerythrine's mechanism of action revealed that 30 minutes following addition of 10 microM chelerythrine, sphingomyelin and phosphatidylcholine (PC) mass decreased confirming our previous findings of neutral, but not acidic, sphingomyelinase activation following treatment with PKC inhibitors [4]. The novel observation that inhibition of PKC isoforms present in WEHI-231 leads to a rapid rise in cellular ceramide as a results of sphingomyelin hydrolysis further suggests an antagonistic relationship between PKC activity and ceramide in the signaling events preceding apoptosis.
WEHI-231是一种小鼠B细胞淋巴瘤，在表面免疫球蛋白（Ig）交联后很容易发生程序性细胞死亡[1]。已证明神经酰胺在暴露于抗Ig抗体、地塞米松和辐射后可诱导WEHI-231细胞凋亡[2]。最近，海莫维茨-弗里德曼等人在内皮细胞中证明，佛波醇-12-肉豆蔻酸酯-13-乙酸酯（PMA）不仅可防止神经酰胺介导的细胞凋亡，还能抑制辐射后神经酰胺的生成[3]。在本文中，我们使用高度特异性的蛋白激酶C（PKC）抑制剂来探索PKC活性、神经酰胺信号传导与细胞凋亡之间的联系。氯化白屈菜红碱和抑酶肽C均能在WEHI-231细胞中触发快速细胞凋亡，并与外源性神经酰胺协同作用诱导细胞凋亡。对氯化白屈菜红碱作用机制的详细研究表明，添加10微摩尔氯化白屈菜红碱30分钟后，鞘磷脂和磷脂酰胆碱（PC）含量降低，这证实了我们之前的研究结果，即PKC抑制剂处理后中性而非酸性鞘磷脂酶被激活[4]。关于抑制WEHI-231细胞中存在的PKC同工型会因鞘磷脂水解导致细胞神经酰胺快速增加这一新发现，进一步表明在细胞凋亡之前的信号传导事件中PKC活性与神经酰胺之间存在拮抗关系。
