부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.brainres.2006.09.036 Byline: Jason DeFuria, Po Chen, Thomas B. Shea Keywords: Stress-activated protein kinase; JNK; MEKK-1; Mitogen-activated protein kinase; Phosphorylation; Neurofilament; Axonal transport; Neuritogenesis Abstract: c-Jun N-terminal kinase (JNK), along with its upstream activator MEKK-1, is typically thought of as a stress-activated kinase that mediates apoptosis. However, additional studies indicate that the MEKK-1/JNK pathway mediates critical aspects of neuronal survival and differentiation. Herein, we demonstrate that transfection of differentiated NB2a/d1 cells with a construct expression constitutively activated (ca) MEKK-1 increases levels of phospho-dependent neurofilament (NF) immunoreactivity within perikarya, while expression of a dominant-negative (dn) form of MEKK-1 decreases it. Steady-state levels of perikaryal phospho-NF immunoreactivity are reduced and the increase resulting from expression of caMEKK-1 is prevented, by the JNK inhibitor SP600125, suggesting that JNK is a major downstream effector of MEKK-1 on NF phosphorylation. Unexpectedly, both caMEKK-1 and dnMEKK-1 inhibited neuritogenesis as well as translocation of NFs into newly elaborated neurites. The JNK inhibitor SP600125 also inhibited NF transport in a dose-dependent manner. caMEKK-1 also prevented the increase in NF transport otherwise mediated by MAP kinase. Finally, both caMEKK-1 and dnMEKK-1 prevented initial neuritogenesis. These findings indicate that the MEKK-1/JNK pathway regulates critical aspects of initial outgrowth, and subsequent stabilization of axonal neurites. Author Affiliation: Departments of Biological Sciences and Biochemistry, Center Cell Neurobiology and Neurodegeneration Research, University of Massachusetts, Lowell, Lowell, MA 01854, USA Article History: Accepted 13 September 2006