REQUIMTE, Laboratório de Microbiologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal.
FEMS Yeast Res. 2013 Nov;13(7):700-5. doi: 10.1111/1567-1364.12069. Epub 2013 Sep 9.
The regulation of protein kinase C (PKC) isoforms by ceramide is still controversial. In this work, the yeast Saccharomyces cerevisiae was used as a model to elucidate the effect of ceramide on the activity of mammalian PKC isoforms. For that, isc1Δ cells, with a deletion in the pathway for ceramide production by hydrolysis of complex sphingolipids, individually expressing mammalian PKCα, δ and ζ were used. Contrary to PKCα and ζ, expression of PKCδ in isc1Δ cells exhibited a similar phenotype to that observed with wild-type yeast cells expressing PKCδ treated with a PKC activator, as phorbol 12-myristate 13-acetate (PMA), specifically a growth inhibition associated with a G2/M cell cycle arrest. Interestingly, in isc1Δ yeast cells expressing PKCδ this phenotype was completely abrogated in the presence of exogenous ceramide. Moreover, using a yeast-based assay previously developed for the screening of PKC inhibitors, it was also shown that, like the known PKC inhibitor NPC 15437, ceramide reduced the PMA-induced growth inhibition, supporting an inhibitory effect of ceramide on PKCδ. Altogether, these results may indicate that ceramide distinctly interfere with the activity of PKCα, δ and ζ. Most importantly, they showed that ceramide is an inhibitor of PKCδ.
蛋白激酶 C（PKC）同工型的调节仍然存在争议。在这项工作中，我们使用酵母酿酒酵母作为模型来阐明神经酰胺对哺乳动物 PKC 同工型活性的影响。为此，我们使用了缺失水解复杂神经酰胺产生神经酰胺途径的 isc1Δ 细胞，分别表达哺乳动物 PKCα、δ 和 ζ。与 PKCα 和 ζ 相反，在 isc1Δ 细胞中表达 PKCδ 表现出与用 PKC 激活剂佛波醇 12-肉豆蔻酸 13-乙酸酯（PMA）处理的野生型酵母细胞中观察到的类似表型，特别是与 G2/M 细胞周期阻滞相关的生长抑制。有趣的是，在表达 PKCδ 的 isc1Δ 酵母细胞中，在外源神经酰胺存在的情况下，这种表型完全被消除。此外，使用先前开发的用于筛选 PKC 抑制剂的酵母测定法，还表明神经酰胺像已知的 PKC 抑制剂 NPC 15437 一样，降低了 PMA 诱导的生长抑制，支持神经酰胺对 PKCδ 的抑制作用。总之，这些结果可能表明神经酰胺明显干扰了 PKCα、δ 和 ζ 的活性。最重要的是，它们表明神经酰胺是 PKCδ 的抑制剂。
