TY - JOUR
T1 - pRb phosphorylation is regulated differentially by cyclin-dependent kinase (Cdk) 2 and Cdk4 in retinoic acid-induced neuronal differentiation of P19 cells
AU - Watanabe, Yumi
AU - Watanabe, Takeshi
AU - Kitagawa, Masatoshi
AU - Taya, Yoichi
AU - Nakayama, Kei Ichi
AU - Motoyama, Noboru
N1 - Funding Information:
We thank Mrs. M. Ikeda and Dr. K. Tamai of MBL (Ina, Japan) for anti-phosphopeptide antibodies and fruitful discussions. We also thank Dr. T. Iwaki (Kyushu University, Japan) for generously providing the P19 cell line and his valuable advice. This work was supported in part by grants from the Ministry of Education, Science, Sports and Culture of Japan (to M. Kitagawa and N. Motoyama). Y. Watanabe was supported by Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists.
PY - 1999/9/25
Y1 - 1999/9/25
N2 - The retinoblastoma protein (pRb) is a key regulator of cell growth, differentiation and survival. pRb(-/-) mice show abnormal neuronal cell death in the developing brain. The function of pRb is regulated by its phosphorylation state. In this study, the phosphorylation of pRb during retinoic acid (RA)-induced neuronal differentiation of P19 cells was examined using site-specific antibodies against pRb phosphorylated at Ser601, Ser605 and Ser773. Although pRb was hyperphosphorylated in undifferentiated P19 cells, Ser601 and Ser773 were not phosphorylated. Upon exposure to RA, however, these two sites became strongly phosphorylated. Cdk4 kinase activity was almost undetectable in undifferentiated P19 cells, but was strongly activated on exposure to RA. In contrast, Cdk2 kinase activity and the phosphorylation of Ser605 were observed in undifferentiated cells as well as in RA-treated cells. These observations suggest that Cdk2 and Cdk4 may phosphorylate different sites of pRb in vivo and that the two sites of pRb examined here are newly phosphorylated during RA-induced neuronal differentiation in P19 cells.
AB - The retinoblastoma protein (pRb) is a key regulator of cell growth, differentiation and survival. pRb(-/-) mice show abnormal neuronal cell death in the developing brain. The function of pRb is regulated by its phosphorylation state. In this study, the phosphorylation of pRb during retinoic acid (RA)-induced neuronal differentiation of P19 cells was examined using site-specific antibodies against pRb phosphorylated at Ser601, Ser605 and Ser773. Although pRb was hyperphosphorylated in undifferentiated P19 cells, Ser601 and Ser773 were not phosphorylated. Upon exposure to RA, however, these two sites became strongly phosphorylated. Cdk4 kinase activity was almost undetectable in undifferentiated P19 cells, but was strongly activated on exposure to RA. In contrast, Cdk2 kinase activity and the phosphorylation of Ser605 were observed in undifferentiated cells as well as in RA-treated cells. These observations suggest that Cdk2 and Cdk4 may phosphorylate different sites of pRb in vivo and that the two sites of pRb examined here are newly phosphorylated during RA-induced neuronal differentiation in P19 cells.
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U2 - 10.1016/S0006-8993(99)01844-2
DO - 10.1016/S0006-8993(99)01844-2
M3 - Article
C2 - 10526130
AN - SCOPUS:0032854316
SN - 0006-8993
VL - 842
SP - 342
EP - 350
JO - Molecular Brain Research
JF - Molecular Brain Research
IS - 2
ER -