Vaudry David, Falluel-Morel Anthony, Basille Magali, Pamantung Tommy F, Fontaine Marc, Fournier Alain, Vaudry Hubert, Gonzalez Bruno J
European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U413, UA CNRS, University of Rouen, France.
J Neurosci Res. 2003 May 1;72(3):303-16. doi: 10.1002/jnr.10530.
The sphingolipid metabolites, ceramides, are critical mediators of the cellular stress response and play an important role in the control of programmed cell death. In particular, ceramides have been shown to induce apoptosis of cerebellar granule cells. We show that pituitary adenylate cyclase-activating polypeptide (PACAP) prevents C2-ceramide-induced apoptosis. The neuroprotective effect of PACAP was dose-dependent and blocked by its antagonist, PACAP6-38, whereas the PACAP-related peptide VIP was inactive. The effect of PACAP on cell survival was mimicked by dibutyryl-cAMP (dbcAMP) and forskolin and prevented by the MEK inhibitor U0126, indicating that both the adenylyl-cyclase and MAP-kinase pathways contribute to the neuroprotective action of the peptide. C2-ceramide and PACAP induced opposite effects on phosphorylated forms of ERK and JNK without affecting the total amounts of ERK and JNK, suggesting that a balance between these two MAP-kinases is critical for the cell survival/death decision. The effect of PACAP on ERK phosphorylation was blocked by U0126, but was not affected by H89 or chelerythrine indicating that PACAP activates ERK through a PKA- and PKC-independent mechanism. C2-ceramide induced a time-dependent activation of caspase-3, enhanced the amount of cleaved caspase-3 and stimulated the DNA fragmentation process, while PACAP strongly inhibited the C2-ceramide-induced activation of caspase-3, reduced the expression of cleaved caspase-3 and blocked DNA fragmentation. Taken together, the present results show that C2-ceramide induces apoptosis of cerebellar granule cells through a mechanism involving activation of caspase-3. Our data also demonstrate that PACAP is a potent inhibitor of C2-ceramide-induced apoptosis.
鞘脂代谢产物神经酰胺是细胞应激反应的关键介质，在程序性细胞死亡的控制中发挥重要作用。特别是，神经酰胺已被证明可诱导小脑颗粒细胞凋亡。我们发现垂体腺苷酸环化酶激活多肽（PACAP）可防止C2 - 神经酰胺诱导的凋亡。PACAP的神经保护作用呈剂量依赖性，并被其拮抗剂PACAP6 - 38阻断，而与PACAP相关的肽血管活性肠肽（VIP）则无活性。二丁酰环磷腺苷（dbcAMP）和福斯高林可模拟PACAP对细胞存活的作用，而MEK抑制剂U0126可阻止这种作用，这表明腺苷酸环化酶和丝裂原活化蛋白激酶（MAP - 激酶）途径均有助于该肽的神经保护作用。C2 - 神经酰胺和PACAP对细胞外信号调节激酶（ERK）和应激活化蛋白激酶（JNK）的磷酸化形式产生相反的影响，而不影响ERK和JNK的总量，这表明这两种MAP - 激酶之间的平衡对于细胞存活/死亡的决定至关重要。PACAP对ERK磷酸化的作用被U0126阻断，但不受H89或白屈菜红碱影响，这表明PACAP通过一种不依赖蛋白激酶A（PKA）和蛋白激酶C（PKC）的机制激活ERK。C2 - 神经酰胺诱导半胱天冬酶 - 3（caspase - 3）的时间依赖性激活，增加裂解的caspase - 3的量并刺激DNA片段化过程，而PACAP强烈抑制C2 - 神经酰胺诱导的caspase - 3激活，降低裂解的caspase - 3的表达并阻断DNA片段化。综上所述，目前的结果表明C2 - 神经酰胺通过涉及caspase - 3激活的机制诱导小脑颗粒细胞凋亡。我们的数据还表明PACAP是C2 - 神经酰胺诱导凋亡的有效抑制剂。
