The role of S6 kinases in the ATM/ATR signaling pathway

描述(申请人提供)：人体细胞的正常功能需要协调许多不同的外部刺激和细胞的后续反应。细胞必须检测是否有合适的营养物质和有丝分裂原可供它们生长或增殖。细胞也会受到各种DNA损伤剂的轰炸，必须通过阻止细胞增殖、修复DNA损伤，然后恢复正常功能来做出反应。这两个途径，有丝分裂原反应和DNA修复，通常被作为单独的途径进行研究。然而，有数据表明，这两条路径可能会相互通信。这个项目的目标是研究细胞内调节有丝分裂反应的酶如何与负责DNA损伤修复的酶相互作用。这个项目的目标是了解S6激酶是否在DNA修复途径中发挥作用。S6激酶受mTOR(哺乳动物雷帕霉素靶标)和PI3K(磷脂酰肌醇-3激酶)的调节。在器官移植中用作免疫抑制剂的细胞增殖抑制剂雷帕霉素被发现抑制mTOR后，mTOR成为细胞增殖研究的前沿。MTOR调控许多细胞过程，包括转录、翻译、增殖和细胞大小决定。PI3K在许多人类癌症中被发现发生突变，它还调节新陈代谢和增殖等许多细胞过程。S6激酶同时受mTOR和PI3K的调节，并被认为介导了mTOR和PI3K的一些功能。最近有数据表明，S6激酶也可能受ATM和ATR的调节，这两种酶在DNA损伤反应中被激活，并激活DNA修复机制。这项提议将开始为评估S6激酶是否真的受ATM/ATR途径调控奠定了基础。这项提议有两个具体目标。在第一个目标中，我们将评估ATM或ATR是否参与激活S6激酶(子目标1A)，并研究是否丝氨酸356(被ATM/ATR修饰的S6激酶上的一个潜在位点)对S6激酶功能重要(子目标1B)。在第二个目标中，我们将研究是否在细胞的DNA损伤区域发现S6激酶(子目标2A)，评估缺乏S6激酶是否对DNA损伤反应有影响(子目标2B)，并评估DNA损伤后S6激酶激活是否导致PI3K和mTOR信号抑制(子目标2C)。有了之前的SCORE资金，我们的实验室已经能够评估是什么激活了S6激酶。这项提议的专业发展目标是达到我们实验室的下一个目标，即了解S6激酶一旦被激活后在细胞中的作用，以及提高我们的生产力和竞争力。

DESCRIPTION (provided by applicant): Normal function of human cells requires coordination of many different external stimuli and the cells' subsequent responses. Cells must detect if there are appropriate nutrients and mitogens available for them to grow or proliferate. Cells are also bombarded with various DNA damaging agents and must respond by stopping cell proliferation, fixing DNA damages, and then resuming their normal function. These two pathways, mitogen response and DNA repair, have often been studied as separate pathways. There are however data to suggest that the two pathways may communicate with each other. The goal of this project is to study how the enzymes inside a cell that regulate mitogenic responses may interact with the enzymes that are responsible for DNA damage repair. The goal of this project is to learn if S6 kinases play a role in the DNA repair pathways. S6 kinases are regulated by the enzymes mTOR (mammalian target of rapamycin) and PI3K (Phosphoinositide-3 kinase). mTOR came to the forefront of cell proliferation research when rapamycin, a cell proliferation inhibitor used as an immunosuppressant in organ transplantation, was found to inhibit mTOR. mTOR regulates many of the cellular processes including transcription, translation, proliferation, and cell size determination. PI3K is found to be mutated in many human cancers, and it also regulates many cellular processes such as metabolism and proliferation. S6 kinases are regulated by both mTOR and PI3K and are thought to mediate some of the mTOR and PI3K functions. Recently there have been data to suggest that S6 kinases may also be regulated by ATM and ATR, enzymes that are activated during DNA damage responses and activate DNA repair mechanisms. This proposal will begin to lay out the fundamental pieces in assessing whether S6 kinases are indeed regulated by the ATM/ATR pathway. There are two specific aims in this proposal. In the first aim, we will assess whether ATM or ATR are involved in activating S6 kinases (sub-aim 1A) as well as studying if serine 356, a potential site on S6 kinases modified by ATM/ATR, is important for S6 kinase function (sub-aim 1B). In the second aim we will study if S6 kinases are found in the DNA damage areas of a cell (sub-aim 2A), assess whether the absence of S6 kinases has an effect on DNA damage responses (sub-aim 2B), and assess whether S6 kinase activation following DNA damage results in inhibition of the PI3K and mTOR signaling (sub-aim 2C). With the previous SCORE funding our laboratory has been able to assess what activates an S6 kinase. The professional developmental objective of this proposal is to reach the next goal of our laboratory, which is to understand what S6 kinases do in cells once they become activated, as well as to increase our productivity and competitiveness.