Radulovic Marko, Hippel Cathrin, Spiess Joachim
Department of Molecular Neuroendocrinology, Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Goettingen, Germany.
J Neurochem. 2003 Mar;84(5):1074-85. doi: 10.1046/j.1471-4159.2003.01594.x.
The physiological role of the corticotropin-releasing factor (CRF) family of peptides has recently been extended by emerging evidence of their cytoprotective effects. To determine whether CRF-mediated cytoprotection is linked to caspase-dependent apoptosis, the effect of CRF on the activation of caspases was investigated in detail in Y79 human retinoblastoma cells. The results presented here demonstrate that the cytoprotective effect of CRF against the actions of camptothecin (CT) was mediated by CRF receptor subtype 1, but not subtype 2. The observed CRF-mediated cytoprotection involved rapid and pronounced suppression of proteolytic processing and activation of procaspase-3, exerted even when CRF was added hours after the application of the cytotoxic agent. Surprisingly, activation of procaspase-3 preceded activation of the initiator procaspases 2, 8, 9 and 10 during CT-induced apoptosis of Y79 cells. The mechanism of the effect of CRF was examined using inhibitors of signalling pathways such as Wortmannin (Akt), cyclic AMP-dependent protein kinase (PKA), extracellular signal-regulated kinase (ERK), protein kinase c (PKC), p38 mitogen-activated protein kinase (p38 MAPK), phospholipase c (PLC), nuclear factor-kappaB (NF-kappaBeta) and c-jun N-terminal kinase (JNK). The involvement of PKA in the mediation of the anti-apoptotic effect of CRF has been established. Taken together, these results demonstrate for the first time that the cytoprotective effect of CRF involved suppression of pro-apoptotic pathways at a site upstream of activation of procaspase-3.
最近，促肾上腺皮质激素释放因子（CRF）家族肽的细胞保护作用的新证据扩展了其生理作用。为了确定CRF介导的细胞保护是否与半胱天冬酶依赖性凋亡有关，我们在Y79人视网膜母细胞瘤细胞中详细研究了CRF对半胱天冬酶激活的影响。本文给出的结果表明，CRF对喜树碱（CT）作用的细胞保护作用是由CRF受体1型介导的，而非2型。观察到的CRF介导的细胞保护作用涉及对procaspase-3蛋白水解加工和激活的快速且显著的抑制，即使在应用细胞毒性剂数小时后添加CRF也能发挥作用。令人惊讶的是，在Y79细胞CT诱导的凋亡过程中，procaspase-3的激活先于起始procaspases 2、8、9和10的激活。我们使用信号通路抑制剂，如渥曼青霉素（Akt）、环磷酸腺苷依赖性蛋白激酶（PKA）、细胞外信号调节激酶（ERK）、蛋白激酶c（PKC）、p38丝裂原活化蛋白激酶（p38 MAPK）、磷脂酶c（PLC）、核因子-κB（NF-κB）和c-jun氨基末端激酶（JNK），研究了CRF作用的机制。PKA参与CRF抗凋亡作用的介导已得到证实。综上所述，这些结果首次表明，CRF的细胞保护作用涉及在procaspase-3激活上游位点抑制促凋亡途径。
