Activation Mechanism of c-Jun Amino-terminal Kinase in the Course of Neural Differentiation of P19 Embryonic Carcinoma Cells

Abstract

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 acidinduced 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 2C⑀, 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.

Inhibited Neurogenesis in JNK1-Deficient Embryonic Stem Cells

“…These findings are consistent with other reports demonstrating a requirement for the JNK pathway in neurogenesis and NFLC regulation modeled in the distinct in vitro system, P19 EC cells (31). Using these cells, the investigators demonstrate that a TAK1-MKK4-JNK signaling pathway is activated and participates in the regulation of the neural differentiation of P19 embryonal carcinoma cells (2). Also, ES cells in which the JNK pathway-specific scaffold protein, JSAP1, is homozygously disrupted exhibit reduced in vitro neurogenesis (38).…”

Immunological regulation of neurogenic niches in the adult brain

“…It has been reported that hydrogels enriched with IFN-γ provides suitable substrate for the differentiation of NSCs into neurons (Leipzig et al, 2010). Pro-neuronal differentiation induced by IFN-γ is mediated by the c-Jun N-terminal kinase ( JNK ) pathways (Kim et al, 2007), which is also required for neuronal differentiation of embryonic stem cells and PC12 cells (Wang et al, 2001; Zentrich et al, 2002; Akiyama et al, 2004; Amura et al, 2005). IFN-γ has shown a dual effect on NSCs, because not only stimulates neuronal differentiation, but also promotes migration and reduces proliferation and cell survival of neural progenitors (Ben-Hur et al, 2003; Wong et al, 2004; Song et al, 2005).…”

A JNK inhibitor SP600125 induces defective cytokinesis and enlargement in P19 embryonal carcinoma cells

“…Previous studies revealed that JNK was phosphorylated and activated during neural differentiation, 11,12 and that this activation was critical for neurogenesis; 4 however, the mechanism underlying regulation by JNK activation remains unclear. Initially, we tried to evaluate the regulatory activation of JNK in detail.…”