Physical and functional interactions between Pim-1 kinase and Cdc25A phosphatase - Implications for the Pim-1-mediated activation of the c-Myc signaling pathway
T. Mochizuki et al., Physical and functional interactions between Pim-1 kinase and Cdc25A phosphatase - Implications for the Pim-1-mediated activation of the c-Myc signaling pathway, J BIOL CHEM, 274(26), 1999, pp. 18659-18666
The pim-1 oncogene encodes a serine/threonine kinase (Pim-1) involved in th
e transduction of cytokine-triggered mitogenic signals. Pim-1 is unique in
that it closely cooperates with c-Myc not only in oncogenesis, but also in
apoptosis induction. However, the molecular basis of Pim-1 function remains
poorly understood, largely because the downstream effector molecule(s) for
Pim-1 kinase has not been identified. Here we provide several lines of evi
dence that Cdc25A cell cycle phosphatase, a direct transcriptional target f
or c-Myc, is a substrate for Pim-1 kinase and functions as an effector for
Pim-1, We found that Pim-1 physically interacts with Cdc25A both in vitro a
nd in vivo and phosphorylates Cdc25A. We also observed that Pim-1-mediated
phosphorylation of Cdc25A increases its phosphatase activity. In addition,
wild-type Pim-1, but not kinase-inactive Pim-1, enhanced Cdc25A-mediated ce
llular transformation and apoptosis, Our results indicate that Cdc25A might
be a key molecule that links Pim-1 and c-Myc and that also ties Pim-1-medi
ated mitogenic signals to cell cycle machinery.