Eblaghie Maxwell C, Lunn J Simon, Dickinson Robin J, Münsterberg Andrea E, Sanz-Ezquerro Juan Jose, Farrell Elizabeth R, Mathers Joanne, Keyse Stephen M, Storey Kate, Tickle Cheryll
Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dow Street, United Kingdom.
Curr Biol. 2003 Jun 17;13(12):1009-18. doi: 10.1016/s0960-9822(03)00381-6.
The importance of endogenous antagonists in intracellular signal transduction pathways is becoming increasingly recognized. There is evidence in cultured mammalian cells that Pyst1/MKP3, a dual specificity protein phosphatase, specifically binds to and inactivates ERK1/2 mitogen-activated protein kinases (MAPKs). High-level Pyst1/Mkp3 expression has recently been found at many sites of known FGF signaling in mouse embryos, but the significance of this association and its function are not known.
We have cloned chicken Pyst1/Mkp3 and show that high-level expression in neural plate correlates with active MAPK. We show that FGF signaling regulates Pyst1 expression in developing neural plate and limb bud by ablating and/or transplanting tissue sources of FGFs and by applying FGF protein or a specific FGFR inhibitor (SU5402). We further show by applying a specific MAP kinase kinase inhibitor (PD184352) that Pyst1 expression is regulated via the MAPK cascade. Overexpression of Pyst1 in chick embryos reduces levels of activated MAPK in neural plate and alters its morphology and retards limb bud outgrowth.
Pyst1 is an inducible antagonist of FGF signaling in embryos and acts in a negative feedback loop to regulate the activity of MAPK. Our results demonstrate both the importance of MAPK signaling in neural induction and limb bud outgrowth and the critical role played by dual specificity MAP kinase phosphatases in regulating developmental outcomes in vertebrates.
细胞内信号转导途径中内源性拮抗剂的重要性日益受到认可。在培养的哺乳动物细胞中有证据表明，双特异性蛋白磷酸酶Pyst1/MKP3能特异性结合并使ERK1/2丝裂原活化蛋白激酶（MAPK）失活。最近在小鼠胚胎中许多已知FGF信号的位点发现了高水平的Pyst1/Mkp3表达，但其这种关联的意义及其功能尚不清楚。
我们克隆了鸡的Pyst1/Mkp3，并表明神经板中的高水平表达与活跃的MAPK相关。我们通过切除和/或移植FGF的组织来源以及应用FGF蛋白或特定的FGFR抑制剂（SU5402），证明FGF信号在发育中的神经板和肢芽中调节Pyst1的表达。我们进一步通过应用特定的丝裂原活化蛋白激酶激酶抑制剂（PD184352）表明，Pyst1的表达是通过MAPK级联反应调节的。在鸡胚中过表达Pyst1会降低神经板中活化MAPK的水平，并改变其形态，阻碍肢芽的生长。
Pyst1是胚胎中FGF信号的诱导性拮抗剂，并在负反馈回路中发挥作用以调节MAPK的活性。我们的结果既证明了MAPK信号在神经诱导和肢芽生长中的重要性，也证明了双特异性MAP激酶磷酸酶在调节脊椎动物发育结果中所起的关键作用。
