Functional analysis of scaffold proteins for mammalian stress-responsive MAP kinase signaling pathways

哺乳动物MAP激酶（MAPK）级联的支架蛋白被认为通过将其信号组分组织成功能模块而在MAPK通路的时空调节中具有关键作用。我们对这些支架蛋白的功能特别感兴趣，主要是c-Jun NH_2-terminal kinase（JNK）/stress-activated protein kinase-associated protein 1（JSAP 1），一种在体外和体内参与JNK MAPK级联的支架蛋白。我们的研究结果总结如下：1）我们首先研究了JSAP 1缺失的ES细胞。我们发现JSAP 1缺失突变体的心肌发生和神经发生过程严重受损，这有力地表明JSAP 1在心肌细胞和神经发育中起着重要作用（JBC，2002 ; BBRC，2005）。2）我们还证明了JSAP 1与黏着斑激酶合作调节细胞运动。（Oncogene，2002 ; JBC 2005）。3）我们进一步表明JSAP 1支架调节细胞-细胞相互作用， ...更多信息 在PC 12 h细胞中，特异性地在NGF诱导的信号传导途径中，通过在PC 12 h细胞中的敲低实验调节N-钙粘蛋白（BBRC，2007）来实现。4）我们还研究了小鼠脑中JSAP 1和JNK的表达。我们通过原位杂交和免疫组织化学分析获得的结果强烈表明JSAP 1-JNK信号传导在发育和成年小鼠脑中起重要作用（JNC，2006）。5）在小脑发育期间，颗粒细胞前体（GCPs）的大量克隆扩增发生在外部颗粒层（EGL）的外部。我们提供的证据表明，JSAP 1和活性JNK优先表达在有丝分裂后的内部EGL祖细胞在发育中的小脑。此外，jsapl缺陷导致小鼠胚胎中增殖的GCP数量增加。此外，在培养的GCPs中过表达JSAP 1导致NeuN阳性细胞数量增加以及JNK激活。总之，这些数据有力地表明，JSAP 1通过调节小脑发育中的JNK活性来促进GCPs的细胞周期退出和分化。少

Scaffold proteins of the mammalian MAP kinase (MAPK) cascades are considered having critical roles in spatio-temporal regulation of MAPK pathways by organizing their signaling components into functional modules. We are particularly interested in the functions of these scaffold proteins, mainly c-Jun NH_2-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1); a scaffold protein that participates in JNK MAPK cascades, both in vitro and in vivo. Our findings are summarized as follows :1) We first investigated the JSAP1-null ES cells. We found that the cardiomyogenesis and neurogenesis process in JSAP1-null mutants were seriously impaired, which strongly indicated that JSAP1 plays an important role in cardiomyocyte and neural development (JBC, 2002 ; BBRC, 2005).2) We also demonstrated that JSAP1 regulates cell movement in cooperation with the focal adhesion kinase (Oncogene, 2002 ; JBC 2005).3) We further showed that JSAP1 scaffold regulates cell-cell interact … More ions in PC12h cells specifically in the NGF-induced signaling pathway, and does so by modulating N-cadherin (BBRC, 2007) through the knock down experiments in PC12h cells.4) We also studied JSAP1 and JNK expression in mouse brains. Our results obtained by in situ hybridization and immunohistochemical analyses strongly suggested that JSAP1-JNK signaling plays important roles in developing and adult mouse brains (JNC, 2006).5) During the development of the cerebellum, massive clonal expansion of granule cell precursors (GCPs) occurs in the outer part of the external granular layer (EGL). We have provided evidence that JSAP1 and active JNK were expressed preferentially in the post-mitotic inner EGL progenitors in the developing cerebellum. Moreover, jsapl deficiency resulted in increasing numbers of proliferating GCPs in mouse embryos. Besides, overexpression of JSAP1 in cultured GCPs led to increased numbers of NeuN-positive cells together with the activation of JNK. Together, these data strongly indicated that JSAP1 promotes the cell-cycle exit and differentiation of GCPs by modulating JNK activity in cerebellar development (in preparation). Less