Lazarovici P, Jiang H, Fink D
Department of Pharmacology, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 91010, Israel.
Mol Pharmacol. 1998 Sep;54(3):547-58. doi: 10.1124/mol.54.3.547.
The 38-amino-acid isoform of pituitary adenylate cyclase-activating polypeptide (PACAP38) elicits a robust outgrowth of neurites in cultured PC12 cells. Initiation of neurite outgrowth occurs within 4-8 hr after the addition of PACAP38. Treatment with PACAP38 does not elicit collateral activation of p140(trk) nerve growth factor receptor tyrosine kinase activity, nor is it associated with tyrosine phosphorylation of suc1-associated neurotrophic factor target, a selective target of neurotrophin tyrosine kinase receptors. Coadministration of epidermal growth factor with PACAP38 elicits an enhanced response. Induction of neurites is also observed on the addition of PACAP38 to dominant negative Src and Ras PC12 cell variants. PACAP38 stimulates extracellular signal-regulated kinase (Erk) activity >10-fold within 5 min, and the effect is augmented by cotreatment with epidermal growth factor. Pretreatment with the cAMP-dependent protein kinase-selective inhibitor, H-89, is ineffective as an antagonist of PACAP38-induced neurite outgrowth, whereas down-regulation of protein kinase C (PKC) by phorbol ester or incubation with PKC-selective inhibitors GF109203X and calphostin C effectively blocks PACAP38-stimulated neurite formation. Stimulation of Erk activity is inhibited by incubation with PD90859, a pharmacological antagonist of the threonine/tyrosine dual-specificity Erk. Inhibition of ligand-stimulated Erk activation prevents PACAP38-induced neurite outgrowth. Collectively, these findings indicate that PACAP38-stimulated neuritogenesis requires PKC and Erk activation but is independent of cAMP-dependent protein kinase, nerve growth factor receptor tyrosine kinase, p21(ras) G protein, and pp60(c-src) cytoplasmic tyrosine kinase.
垂体腺苷酸环化酶激活多肽的38个氨基酸异构体（PACAP38）可促使培养的PC12细胞中神经突强劲生长。添加PACAP38后4 - 8小时内开始出现神经突生长。用PACAP38处理不会引发p140（trk）神经生长因子受体酪氨酸激酶活性的旁系激活，也与神经营养因子酪氨酸激酶受体的选择性靶点suc1相关神经营养因子靶点的酪氨酸磷酸化无关。表皮生长因子与PACAP38共同给药可引发增强的反应。将PACAP38添加到显性负性Src和Ras PC12细胞变体中也可观察到神经突的诱导。PACAP38在5分钟内刺激细胞外信号调节激酶（Erk）活性增加10倍以上，并且与表皮生长因子共同处理可增强该效应。用cAMP依赖性蛋白激酶选择性抑制剂H - 89预处理作为PACAP38诱导的神经突生长的拮抗剂无效，而佛波酯下调蛋白激酶C（PKC）或与PKC选择性抑制剂GF109203X和钙泊三醇C孵育可有效阻断PACAP38刺激的神经突形成。用苏氨酸/酪氨酸双特异性Erk的药理拮抗剂PD90859孵育可抑制Erk活性的刺激。抑制配体刺激的Erk激活可防止PACAP38诱导的神经突生长。总的来说，这些发现表明PACAP38刺激的神经突形成需要PKC和Erk激活，但独立于cAMP依赖性蛋白激酶、神经生长因子受体酪氨酸激酶、p21（ras）G蛋白和pp60（c - src）细胞质酪氨酸激酶。
