1. Developmental changes in the localization of activated C-JUN N-terminal kinase (JNK/SAPK) in the chick spinal cord
- Author
-
Kayoko Yamashita, Runa Masaki, Kazuaki Hirata, Ritsuko Ohtani-Kaneko, and Takashi Shiga
- Subjects
Aging ,Neurofilament ,Proto-Oncogene Proteins c-jun ,Chick Embryo ,Biology ,White matter ,medicine ,Animals ,Tissue Distribution ,Phosphorylation ,Cyclic AMP Response Element-Binding Protein ,Cytoskeleton ,Activating Transcription Factor 2 ,Kinase ,General Neuroscience ,Cyclin-dependent kinase 5 ,c-jun ,JNK Mitogen-Activated Protein Kinases ,Cyclin-Dependent Kinase 5 ,Spinal cord ,Immunohistochemistry ,Cyclin-Dependent Kinases ,Cell biology ,medicine.anatomical_structure ,Spinal Cord ,Biochemistry ,Mitogen-activated protein kinase ,biology.protein ,Mitogen-Activated Protein Kinases ,Transcription Factors - Abstract
To examine the role of c-Jun N-terminal kinase (JNK/SAPK) in the developing nervous system of vertebrates, the localization of an active form of JNK, phosphorylated JNK (p-JNK), was studied in the lumbosacral spinal cord of the chick embryo. We also examined the localization of phosphorylated neurofilaments (NFs, potential targets of p-JNK) and cyclin-dependent kinase 5 (Cdk5), which is known to phosphorylate cytoskeletal proteins, including NFs, and compared their expression with that of p-JNK. Additionally, the localization of phosphorylated forms of c-Jun and ATF-2 was compared with that of p-JNK. On embryonic day 3 (E3), the expression of p-JNK was observed in regions containing early-projecting axons. Axons in these regions also expressed phosphorylated NFs. Subsequently, on E5 and E8, the expression of both p-JNK and phosphorylated NFs increased concomitantly in the axonal tracts in the spinal white matter. Thus, white matter expressed both p-JNK and phosphorylated NFs, whereas there was only weak expression of Cdk5. By E13, the spinal cord expression pattern of p-JNK and phosphorylated NFs had changed compared to earlier ages. Although phosphorylated NFs were still expressed in the white matter, the expression of p-JNK was decreased in axons in the white matter, whereas strong p-JNK expression appeared in cell nuclei in the gray matter. In summary, the present study revealed that the localization of p-JNK in the spinal cord changes dramatically from axons to cell nuclei during development, suggesting multiple roles of p-JNK, depending on the developmental age. J. Comp. Neurol. 426:622โ631, 2000. © 2000 Wiley-Liss, Inc.
- Published
- 2000