Gil C, Chaïb-Oukadour I, Pelliccioni P, Aguilera J
Departament de Bioquímica i de Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, E-08193 (Barcelona), Catalunya, Bellaterra, Spain.
FEBS Lett. 2000 Sep 15;481(2):177-82. doi: 10.1016/s0014-5793(00)02002-0.
Previous reports have demonstrated that tetanus toxin (TeTx) induces activation and down-regulation of protein kinase C (PKC). In the present work the differential activation of PKC isoforms and of signal transduction pathways, including nerve growth factor receptor trkA, phospholipase Cgamma-1 (PLCgamma-1), and extracellular regulated kinases 1 and 2 (ERK-1/2) by TeTx in a synaptosome-enriched P(2) fraction from rat brain is reported. TeTx induces clear translocation from the soluble (cytosolic) compartment to the particulate (membranous) compartment of PKC-beta, -gamma and -delta isoforms, whereas PKC-epsilon showed a slight decrease of its soluble fraction immunoreactivity. On the contrary, the PKC-zeta isoform shows no consistent response, whereas down-regulation of total PKC-alpha immunoreactivity is shown. Immunoprecipitation assays against phosphotyrosine show an increase of trkA and PLCgamma-1 phosphorylation. Moreover, trkA activation is corroborated using phospho-specific antibodies against phosphorylated trkA. On the other hand, TeTx-induced stimulation of mitogen-activated protein (MAP) kinase activity is observed, this event also being detected by Western analysis using phospho-specific antibodies against ERK-1/2.
先前的报道表明，破伤风毒素（TeTx）可诱导蛋白激酶C（PKC）的激活和下调。在本研究中，报道了TeTx在大鼠脑富含突触体的P(2)组分中对PKC亚型以及包括神经生长因子受体trkA、磷脂酶Cγ-1（PLCγ-1）和细胞外调节激酶1和2（ERK-1/2）在内的信号转导途径的差异激活。TeTx诱导PKC-β、-γ和-δ亚型从可溶性（胞质）区室向颗粒性（膜性）区室明显转位，而PKC-ε的可溶性组分免疫反应性略有下降。相反，PKC-ζ亚型未表现出一致的反应，而总PKC-α免疫反应性则出现下调。针对磷酸酪氨酸的免疫沉淀试验显示trkA和PLCγ-1磷酸化增加。此外，使用针对磷酸化trkA的磷酸特异性抗体证实了trkA的激活。另一方面，观察到TeTx诱导的丝裂原活化蛋白（MAP）激酶活性的刺激，使用针对ERK-1/2的磷酸特异性抗体进行蛋白质印迹分析也检测到了这一事件。
