Role of MAP kinase cascades in the regulation of diverse cellular functions

1.我们研究了调控ERK-MAP激酶核转位和滞留的可能分子机制。一个新的26-kD蛋白(P26)在N端含有SH3结构域，在C端含有3个Ankyrin重复序列，被认为是参与调节ERK-MAP激酶核转位/保留的候选分子。P26的过表达抑制了HGF诱导的ERK-MAP激酶在MDCK细胞中的核定位/保留，而siRNA介导的P26的敲除则增强了这一作用。P26与一种新的120 kDa蛋白(P120)特异地相互作用，这种相互作用被ERK-MAP激酶下游的效应分子p90^；rsk&gt；抑制P26的磷酸化。这些结果表明ERK-MAP激酶的核转位/保留是由ERK-MAP信号通路自身调节的。一种新的RhoA的Gdp/Gtp交换因子gef-H1被证明是ERK-…的生理底物更多的贴图激活码。细胞外信号调节蛋白激酶途径上调了细胞生长因子-H1的表达。ERK-MAP激酶对Thr^-678&gt；的磷酸化诱导了环境基金-H1的激活，从而激活了RhoA，而它诱导了对rac1的抑制。此外，siRNA介导的全球环境基金-H1的敲除增强了细胞的运动反应。这些结果提示，细胞生长因子-H1参与了ERK-MAF激酶通路介导的细胞运动性反应。C-Jun氨基末端酶(JNK)参与了胞质分裂的调节。JNK通过磷酸化角蛋白8来诱导角蛋白细丝的松弛，这似乎是细胞发生胞质分裂的先决条件之一。50μM PD98059与低浓度(3 NM)长春花碱联合应用可诱导G2/M期阻滞的T24细胞发生明显的细胞死亡反应，但对G1/S期阻滞的T24细胞无明显影响。在此条件下，观察到细胞周期蛋白B、Plk1和Aurora-B的积累。这些结果表明，ERK-MAP激酶通路参与了纺锤体检查点的调节。较少

1. We have examined a possible molecular mechanism through which nuclear translocation and retention of ERK-MAP kinases is regulated. A novel 26-kD protein (p26) which contains a SH3 domain at the N-terminus and three ankyrin repeat sequences at the C-terminus has been identified as a candidate molecule which is involved in the regulation of nuclear translocation/retention of ERK-MAP kinases. Overexpression of p26 suppresses the HGF-induced nuclear localization/retention of ERK-MAP kinases in MDCK cells, while siRNA-mediated knockdown of p26 enhances it. p26 interact specifically with a novel 120-kDa protein (p120), and this interaction is suppressed by the phosphorylation of p26 by p90^<rsk>, an effector molecule downstream of the ERK-MAP kinases. These results suggest that nuclear translocation/retention of ERK-MAP kinases is regulated by the ERK-MAP kinase signaling pathway by itself.2. A novel GDP/GTP exchanger of RhoA, GEF-H1, has been shown to be a physiological substrate of ERK- … More MAP kinases. Expression of GEF-H1 is up-regulated by the ERK MAP kinase pathway. Phosphorylation of Thr^<678> by ERK-MAP kinases induces the activation of GEF-H1 thereby activates RhoA, whereas it induces the inhibition of Rac1. Furthermore, siRNA-mediated knock down of GEF-H1 enhances the cell motility response. These results suggest that GEF-H1 is involved in the ERK-MAF kinase pathway-mediated cell motility response.3. c-Jun N-Terminal Kinase (JNK) has been shown to be involved in the regulation of cytokinesis. JNK phosphorylates keratin 8 to induce the relaxation of keratin filaments, which appear to be one of the prerequisites for cells to undergo cytokinesis.4. Combination of 50 μM PD98059 and a low concentration (3 nM) of vincristin induces marked apoptotic cell death response in G_2/M-phase-arrested T24 cells, but not in G_1-/S-phase-arrested cells. Under such conditions, accumulation of cyclinB, Plk1and Aurora-B has been observed. These results suggest that ERK-MAP Kinase pathway is involved in the regulation of spindle check point. Less