SIGNAL TRANSDUCTION TO P70 S6 KINASE 1

描述（改编自申请人摘要）： 多种信号转导过程可导致多种 分化发育不当或恶性疾病 转型 PI 3 K在细胞增殖中起关键作用。 直到 然而，最近关于PI 3 K如何发信号知之甚少。 P70 S6 K1是 第一个信号蛋白激酶显示在PI 3 K下游起作用。 以来 那么，S6 K1的激活已经被证明需要几种脂质依赖性的 激酶，与活化的rho家族G蛋白（Cdc 42/rac 1）结合，和 通过不同的输入在多个位点磷酸化。 强调其 重要的是，癌基因产物如Dbl、TIAM-1和Akt特异性地 激活S6 K1，T细胞免疫抑制剂雷帕霉素和地塞米松 专门对抗其激活。 S6 K1的两种同种型，α-1和 α-2被认为调节基因表达和蛋白质翻译， 分别 然而，人们对其下游目标知之甚少。 的 在本申请中提出的研究解决了关于该法规的问题 S6 K1的活化、下游信号传导及其在细胞增殖中的作用。 第一个目标是通过以下方式确定S6 K1激活的机制： 确定自抑制结构域的磷酸化和两个关键 连接区中的S371和T389位点受到调控， S6 K1的激活。 此外，这些事件 与T229的磷酸化相协调， 将检查PDK 1的激活回路。 第二个目标是利用分子和生物化学技术 方法，S6 K1相关蛋白，并评估其在调节 S6 K1或通过S6 K1发信号。 预计这些蛋白质要么位于上游， 调节子、下游靶点或组装S6 K1的支架蛋白 信号复合体 第三个目标是表征S6 K1在一个细胞中的生物学功能。 细胞系统将允许阐明S6 K1和细胞之间的联系 细胞周期机制 第四个目的是表征在一个细胞中表达S6 K1的转基因小鼠。 转基因T细胞模型，评估蛋白激酶在小鼠中的作用 T细胞增殖、分化，最终发挥功能。 由于几 造血癌基因和T细胞免疫抑制剂调节S6 K1活性 这将允许检查S6 K的功能。

Description(adapted from the applicant's abstract): Inappropriate regulation of a variety of signal transduction processes can result in a multitude of diseases due to improper differentiation and development or malignant transformation. PI3K plays a critical role in cell proliferation. Until recently, however, little was known regarding how PI3K signaled. P70S6K1 was the first signaling protein kinase shown to act downstream of PI3K. Since then, S6K1 activation has been shown to require several lipid-dependent kinases, binding to activated rho family G proteins (Cdc42/rac1), and phosphorylation at multiple sites by distinct inputs. Underscoring its importance, oncogene products such as Dbl, TIAM-1, and Akt specifically activate S6K1, and the T cell immunosuppressants rapamycin and dexamethasone specifically antagonize its activation. The two isoforms of S6K1, alpha-1 and alpha-2, are believed to regulate gene expression and protein translation, respectively. However, little is known of their downstream targets. The research proposed in this application addresses issues regarding the regulation of S6K1 activation, downstream signaling and its role in cell proliferation. The first objective is to define the mechanisms of S6K1 activation by determining how phosphorylation of the autoinhibitory domain and two critical sites in the linker region, S371 and T389, are regulated, and the consequences of these phosphorylations to S6K1 activation. In addition, how these events are coordinated with and cooperate with the phosphorylation of T229 in the activation loop by PDK1 will be examined. The second objective is to identify, using molecular and biochemical approaches, S6K1 associated proteins and assess their roles in regulation of S6K1 or signaling by S6K1. These proteins are expected to be either upstream regulators, downstream targets, or scaffolding proteins that assemble the S6K1 signaling complex. The third objective is to characterize the biological function of S6K1 in a cell system that will allow elucidation of the linkage between S6K1 and the cell cycle machinery. The fourth objective is to characterize transgenic mice expressing S6K1 in a transgenic T-cell model, to assess the role of the protein kinase in murine T-cell proliferation, differentiation, and ultimately function. Since several hematopoietic oncogenes and T cell immunosuppressants modulate S6K1 activity this will allow the examination of the functions of S6K.