Activation mechanism of c-Jun amino-terminal kinase in the course of neural differentiation of P19 embryonic carcinoma cells.
P19 embryonic carcinoma cells, a model system for studying early development and differentiation, can differentiate into neurons and primitive endoderm-like cells depending on the culture conditions. We have previously reported that the activation of c-Jun amino-terminal kinase (JNK) is required for the retinoic acid-induced neural differentiation of P19 cells. However, the signaling pathway(s) responsible for the activation of JNK has not been known. In this study, we demonstrated that activities of MAPK kinase 4 (MKK4) and TAK1, one of the upstream kinases of MKK4, were enhanced in the neurally differentiating cells. Inhibition of the neural differentiation by an overexpression of protein phosphatase 2Cepsilon, an inactivator of TAK1, suggested a critical role of the TAK1 signaling pathway during the differentiation. Confocal microscopic analysis indicated that TAK1, phospho-MKK4, and phospho-JNK were colocalized with tubulin in the neurites and localized also in the nuclei of the differentiating cells. In contrast, two TAK1-binding proteins, TAB1 and TAB2, which are involved in the activation of TAK1, were localized in the neurites and the nuclei of the differentiating cells, respectively. These results suggest that two distinct TAK1-MKK4-JNK signaling pathways are independently activated at the different intracellular locations and may participate in the regulation of the neural differentiation of P19 cells.
Akiyama
Shoko
S
Departments of Biochemistry and Clinical Oncology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
Yonezawa
Takayuki
T
Kudo
Tada-Aki
TA
Li
Ming Guang
MG
Wang
Hong
H
Ito
Michihiko
M
Yoshioka
Katsuji
K
Ninomiya-Tsuji
Jun
J
Matsumoto
Kunihiro
K
Kanamaru
Ryunosuke
R
Tamura
Shinri
S
Kobayashi
Takayasu
T
D000818:Animals; D015152:Blotting, Northern; D018236:Carcinoma, Embryonal / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004789:Enzyme Activation; D019084:Fluorescent Antibody Technique, Indirect; D018507:Gene Expression Regulation, Developmental; D048031:JNK Mitogen-Activated Protein Kinases; D048768:MAP Kinase Kinase Kinase 4; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011233:Precipitin Tests; D000071636:Protein Phosphatase 2C; D015398:Signal Transduction; D014162:Transfection; D014212:Tretinoin / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D000099151:MAP Kinase Kinase Kinase 7
D048031:JNK Mitogen-Activated Protein Kinases; D048768:MAP Kinase Kinase Kinase 4; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C; D014212:Tretinoin; D014404:Tubulin; D000099151:MAP Kinase Kinase Kinase 7; C482780:Map3k4 protein, mouse