Functional analysis of the scaffold protein JSAP1 in the developing mouse cerebellum

哺乳动物MAP激酶（MAPK）级联的支架蛋白被认为通过将信号组分组织成功能模块来在这些通路的时空调节中起作用。我们已经研究了c-Jun氨基末端激酶（JNK）/应激活化蛋白激酶相关蛋白1（JSAP 1）的功能，JSAP 1是一种参与INK MAPK级联反应的支架蛋白。我们的研究结果总结如下：1）我们首先产生了携带lox-P侧翼（foxed）Jsap 1基因的基因工程小鼠，并将foxed Jsap 1缺失突变体特异性地引入神经谱系。Jsap 1条件性敲除小鼠显示出与JSAP 1缺失小鼠基本上相同的表型，表明Jsap 1缺陷小鼠的新生儿死亡是由神经系统缺陷引起的（Neurosci.信件：2）我们表明，JSAP 1支架特异性地在NGF诱导的信号传导途径中调节PC 12 h细胞中的细胞-细胞相互作用，并且通过调节N-cad来实现 ...更多信息 herin（Biochem. Biophys. Res. Commun.，2007）通过PC 12 h细胞中的敲低实验。3）我们还研究了JSAP 1和JNK在小鼠脑中的表达。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（J. Neuroshem.，4）在小脑的发育过程中，颗粒细胞前体（GCP）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，Jsap 1缺陷导致小鼠胚胎中增殖的GCPs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 thought to function in the spatio-temporal regulation of these pathways by organizing the signaling components into functional modules. We have examined the functions of c-Jun NH,-terminal kinase (JNK)/stress-activated protein kinase-associated protein 1 (JSAP1), a scaffold protein that are involved in INK MAPK cascades. Our findings are summarized as follows:1) We first generated genetically engineered mice carrying a lox-P-flanked (foxed) Jsap 1 gene, and introduced the foxed Jsap 1 deletion mutant specifically into the neural lineage. The Jsap 1 conditional knockout mice showed essentially the same phenotypes as the JSAP1-null mice, suggesting that the neonatal death of Jsap 1-deficient mice is caused by defects in the nervous system (Neurosci. Lett., 2007).2) We showed that JSAP1 scaffold regulates cell-cell interactions in PC12h cells specifically in the NGF-induced signaling pathway, and does so by modulating N-cad … More herin (Biochem. Biophys. Res. Commun., 2007) through the knock down experiments in PC12h cells.3) 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 (J. Neurothem., 2006).4) 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, Jsap 1 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