Nakayama H, Numakawa T, Ikeuchi T, Hatanaka H
Department of Pharmacology, Nara Medical University, Kashihara, Nara, Japan.
J Neurochem. 2001 Nov;79(3):489-98. doi: 10.1046/j.1471-4159.2001.00602.x.
We have investigated mechanisms of nicotine-induced phosphorylation of extracellular signal-regulated protein kinase (p42/44 MAP kinase, ERK) and cAMP response element binding protein (CREB) in PC12h cells. Nicotine transiently induced ERK phosphorylation at more than 1 microM. The maximal level of nicotine-induced ERK phosphorylation was lower than that of the membrane depolarization induced and, to a great extent, the nerve growth factor (NGF)-induced ERK phosphorylation. Nicotinic acetylcholine receptor (nAChR) alpha7 subunit-selective inhibitors had no significant effect on nicotine-induced ERK phosphorylation. L-Type voltage-sensitive calcium channel antagonists inhibited nicotine-induced ERK phosphorylation. Calcium imaging experiments showed that alpha7-containing nAChR subtypes were functional at 1 microM of nicotine in the nicotine-induced calcium influx, and non-alpha7 nAChRs were prominent in the Ca(2+) influx at 50 microM of nicotine. An expression of dominant inhibitory Ras inhibited nicotine-induced ERK phosphorylation. A calmodulin antagonist, a CaM kinase inhibitor, a MAP kinase kinase inhibitor inhibited nicotine-induced ERK and CREB phosphorylation. The time course of the phosphorylation of CREB induced by nicotine was similar to that of ERK induced by nicotine. These results suggest that non-alpha7 nAChRs are involved in nicotine-induced ERK phosphorylation through CaM kinase and the Ras-MAP kinase cascade and most of the nicotine-induced CREB phosphorylation is mediated by the ERK phosphorylation in PC12h cells.
我们研究了尼古丁诱导PC12h细胞中细胞外信号调节蛋白激酶（p42/44丝裂原活化蛋白激酶，ERK）和环磷酸腺苷反应元件结合蛋白（CREB）磷酸化的机制。尼古丁在浓度高于1 microM时可短暂诱导ERK磷酸化。尼古丁诱导的ERK磷酸化的最大水平低于膜去极化诱导的水平，并且在很大程度上低于神经生长因子（NGF）诱导的ERK磷酸化水平。烟碱型乙酰胆碱受体（nAChR）α7亚基选择性抑制剂对尼古丁诱导的ERK磷酸化无显著影响。L型电压敏感性钙通道拮抗剂抑制尼古丁诱导的ERK磷酸化。钙成像实验表明，含α7的nAChR亚型在1 microM尼古丁诱导的钙内流中起作用，而非α7 nAChRs在50 microM尼古丁诱导的Ca(2+)内流中占主导地位。显性抑制性Ras的表达抑制尼古丁诱导的ERK磷酸化。钙调蛋白拮抗剂、CaM激酶抑制剂、丝裂原活化蛋白激酶激酶抑制剂抑制尼古丁诱导的ERK和CREB磷酸化。尼古丁诱导的CREB磷酸化的时间进程与尼古丁诱导的ERK磷酸化的时间进程相似。这些结果表明，非α7 nAChRs通过CaM激酶和Ras-丝裂原活化蛋白激酶级联反应参与尼古丁诱导的ERK磷酸化，并且在PC12h细胞中，大多数尼古丁诱导的CREB磷酸化是由ERK磷酸化介导的。
