GANGLIOSIDE SIGNALING CASCADES FOR GLIOMA GROWTH

描述：（改编自研究者摘要）神经节苷脂是 细胞生长的有效调节剂，并可能对神经胶质瘤产生深远的影响 增殖 一般的假设是神经节苷脂可以刺激 胶质瘤增殖通过激活特定的信号转导通路。 这是基于他们的发现，U-1242 MG胶质瘤的外源性治疗 神经节苷脂GM-I刺激细胞DNA合成， 涉及细胞外的快速激活的机制 信号调节蛋白激酶2（Erk 2）和p70 S6激酶（p70 s6 k）。 他们 将使用这些细胞作为模型来研究 神经节苷脂刺激信号转导，并认为这些研究应该 阐明神经节苷脂在细胞增殖中的作用，这很重要 在人类脑肿瘤中。 在具体目标1中，他将描述神经节苷脂的相互作用， 并将这些与Erk 2的激活相关， p70 s6 k信号级联。 他将使用代谢抑制剂来测试 内源性神经节苷脂的生物合成对于外源性神经节苷脂的信号传导是重要的。 GM 1. 他还将测试Erk 2的激活是否与 GM 1与细胞表面蛋白或与插入物的稳定结合 进入细胞膜。 基于对渥曼青霉素的研究， 磷脂酰肌醇3 '-激酶（PI 3 K）的抑制剂，他提出GM I 激活PI 3 K。 在特定目标2中，他将测量体内刺激的GM 1 产生3-磷酸肌醇，以估计PI 3 K活化并确定 酪氨酸激酶抑制剂和G蛋白抑制剂对此的影响 活动 在B部分，他将鉴定出受转基因刺激的分子， 使用生物化学、免疫学和分子方法测定PI 3 K。 c部分所 他将创造出PI 3 K激活缺陷的细胞， 研究GM 1介导的Erk 2和p70 s6 k活化。 GM 1通过涉及Raf-1激活的机制刺激Erk 2 癌蛋白以及刺激p70 s6 k通过一个未知的途径。 在 具体目标3，他将使用遗传和生物化学的方法来检查 GM 1是否刺激Ras，一种众所周知的Raf-1激活剂。 他还将 使用新的Raf突变体和磷酸氨基酸谱来鉴定新的 GM 1刺激的Raf调节。他还将使用体外激酶测定， 检测GM 1是否通过丝氨酸/苏氨酸激酶Akt激活p70 s6 k。

DESCRIPTION: (adapted from the investigator's abstract) Gangliosides are potent modulators of cell growth and could have profound effects on glioma proliferation. The general hypothesis is that gangliosides can stimulate glioma proliferation by activating specific signal transduction pathways. This is based on their finding that exogenous treatment of U-1242 MG glioma cells with ganglioside GM I stimulated DNA synthesis by a signaling mechanism involving the rapid activation of the extracellular signal-regulated protein kinase 2 (Erk2) and p70 S6 kinase (p70s6k). They will use use these cells as a model for studying the mechanisms by which gangliosides stimulate signal transduction, and believes the studies should clarify the role of gangliosides in cell proliferation and this is important in human brain tumors. In Specific Aim 1 he will characterize ganglioside interactions at and within the cell surface and relate these to activation of the Erk2 and p70s6k signaling cascades. He will use metabolic inhibitors to test whether endogenous ganglioside biosynthesis is important for signaling by exogenous GM 1. He will also test whether activation of Erk2 correlates with the stable association of GM l with cell surface proteins or with the insertion of GM I into the membrane. Based on studies with wortmannin, a specific inhibitor of phosphatidylinositol 3'-kinase, (PI3K), he proposes that GM I activates PI3K. In Specific Aim 2 he will measure GM1stimulated in vivo production of 3-phosphoinositides to estimate PI3K activation and determine the effects of tyrosine kinase inhibitors and G-protein inhibitors on this activity. In part b he will identify GMI-stimulated molecules that regulate PI3K using biochemical, immunological and molecular approaches. In part c he will create cells that are defective for PI3K activation and use them for studying GM1 -mediated activation of Erk2 and p70 s6k. GM1 stimulates Erk2 by a mechanism involving activation of the Raf-1 oncoprotein as well as stimulates p70s6k by an uncharacterized pathway. In Specific Aim 3, he will use genetic and biochemical approaches to examine whether GM1 stimulates Ras, a well known activator of Raf-1. He will also use novel Raf mutants and phosphoamino acid profiles to to identify novel GM1-stimulated regulation of Raf. He will also use in vitro kinase assays to test whether GM1 activates p70s6k through the serine/threonine kinase Akt.