Kano Y, Nohno T, Shimada K, Nakagiri S, Hiragami F, Kawamura K, Motoda H, Numata K, Murai H, Koike Y, Inoue S, Miyamoto K
Department of Occupational Therapy, School of Health Science, Kibi International University, Takahashi, Okayama 716-8508, Japan.
Brain Res. 2007 Jun 18;1154:1-7. doi: 10.1016/j.brainres.2007.03.087. Epub 2007 Apr 5.
Although it is known that sustained activation of classical mitogen-induced protein kinase (MAPK, also known as ERK) induced by nerve growth factor (NGF) plays an important role in the induction of neurite outgrowth, the role of p38 MAPK in neural cell function is still not clear. We developed two neuronal cell lines from PC12 cells, PC12m3 and PC12m32, in which NGF-induced neurite outgrowth is impaired and that show neurite outgrowth in response to hyperosmotic shock. The frequencies of neurite outgrowth of PC12m3 and PC12m32 cells induced by osmotic shock were approximately 10- and 12-fold greater, respectively, than that in PC12 parental cells. The p38 MAPK pathway inhibitor SB203580 but not the ERK pathway blocker U0126 inhibited the ability of PC12m3 and PC12m32 cells to induce neurite outgrowth in response to osmotic shock. Furthermore, expression of a nonactivable form of p38 but not that of wild-type p38 significantly blocked neurite outgrowth induced by osmotic shock. The extent of phosphorylation of p38 MAPK induced by osmotic shock in PC12m32 cells was much greater than that in PC12 parental cells. The upstream kinases MKK3 and MKK6, which phosphorylate and activate p38 MAPK, also showed higher levels in PC12m32 cells than in PC12 parental cells when treated with osmotic shock. Inhibition of p38 MAPK by SB203580 resulted in inhibition of the activity of the transcription factor CREB, which is activated by osmotic shock. These findings indicate that activation of CREB mediated by a p38 pathway distinct from the NGF signaling pathway may be required for neurite outgrowth.
尽管已知神经生长因子（NGF）诱导的经典丝裂原诱导蛋白激酶（MAPK，也称为ERK）的持续激活在神经突生长的诱导中起重要作用，但p38 MAPK在神经细胞功能中的作用仍不清楚。我们从PC12细胞中开发了两种神经元细胞系，PC12m3和PC12m32，其中NGF诱导的神经突生长受损，并且它们在高渗休克反应中显示出神经突生长。渗透压休克诱导的PC12m3和PC12m32细胞神经突生长频率分别比PC12亲代细胞高约10倍和12倍。p38 MAPK途径抑制剂SB203580而非ERK途径阻滞剂U0126抑制了PC12m3和PC12m32细胞在渗透压休克反应中诱导神经突生长的能力。此外，不可激活形式的p38而非野生型p38的表达显著阻断了渗透压休克诱导的神经突生长。PC12m32细胞中渗透压休克诱导的p38 MAPK磷酸化程度远高于PC12亲代细胞。磷酸化并激活p38 MAPK的上游激酶MKK3和MKK6在渗透压休克处理时，在PC12m32细胞中的水平也高于PC12亲代细胞。SB203580对p38 MAPK的抑制导致了转录因子CREB活性的抑制，CREB由渗透压休克激活。这些发现表明，可能需要由不同于NGF信号通路的p38途径介导的CREB激活来促进神经突生长。
