Developmental changes in the localization of activated C-JUN N-terminal kinase (JNK/SAPK) in the chick spinal cord.
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.
Ohtani-Kaneko
R
R
Department of Anatomy, St. Marianna University School of Medicine, Miyamae-ku, Kawasaki 216-8511, Japan. r2kaneko@marianna-u.ac.jp
Shiga
T
T
Yamashita
K
K
Masaki
R
R
Hirata
K
K
D051698:Activating Transcription Factor 2; D000375:Aging / Q000378:metabolism*; D000818:Animals; D002642:Chick Embryo / Q000378:metabolism* / Q000502:physiology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D013116:Spinal Cord / Q000196:embryology*; D014018:Tissue Distribution; D014157:Transcription Factors / Q000378:metabolism
D051698:Activating Transcription Factor 2; D017362:Cyclic AMP Response Element-Binding Protein; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases