SciELO - Scientific Electronic Library Online

vol.38 issue2-3The effect of temperature and irradiance on the growth and carotenogenic capacity of seven strains of Dunaliella salina (Chlorophyta) cultivated under laboratory conditionsRoles of nibrin and ATM/ATR kinases on the G2 checkpoint under endogenous or radio-induced DNA damage author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand




Related links


Biological Research

Print version ISSN 0716-9760


INOSTROZA, JUAN et al. Role of the phosphatase PP4 in the activation of JNK-1 in prostate carcinoma cell lines PC-3 and LNCaP resulting in increased AP-1 and EGR-1 activity . Biol. Res. [online]. 2005, vol.38, n.2-3, pp.163-178. ISSN 0716-9760.

The specific signaling connections between the mitogen-activated protein kinases (MAPK) such as c-Jun N-terminal kinase (JNK-1) and phosphatases PP4 and M3/6, affecting the family of early nuclear factors, is complex and remains poorly understood. JNK-1 regulates cellular differentiation, apoptosis and stress responsiveness by up-regulating early nuclear factors such as c-Jun, a member of the activating protein (AP-1) family, and the Early Growth Factor (EGR-1). C-Jun, when phosphorylated by c-Jun N-terminal kinase (JNK-1) associates with c-Fos to form the AP-1 transcription factor that activates gene expression. We have investigated the regulation of the JNK-1 kinase by co-transfecting phosphatases PP4 and M3/6 in prostate cancer cell lines PC-3 and LNCaP, which have been previously stimulated with human EGF or cisplatin. Co-transfections of plasmids expressing the JNK-1 and the serine/threonine phosphatases PP4 resulted in a significant increase in JNK-1 activity in both PC3 and LNCaP cells. In contrast, co-transfection of JNK-1 with the dual specific phosphatase serine/threonine M3/6 showed only a marginal effect in JNK-1 activity. The phosphatase M3/6 also failed in blocking the induction of JNK-1 activity observed in presence of PP4. The higher activity of JNK-1 was associated with increased activities of the factors c-Jun/AP-1 and EGR-1. This suggests that JNK-1 activity in PC-3 and LNCaP cells requires not only active PP4 for stable maintenance but also suggests that the relative degree of phosphorylation of multiple cellular components is the determinant of JNK-1 stability.

Keywords : prostate cancer; phosphatase PP4; kinase JNK-1.

        · text in English     · English ( pdf )


Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License