Regulation and Role of CREB in Cellular Genotoxic Response to Xenobiotics

描述(申请人提供)：CREB(cAMP反应元件结合)转录因子是一种刺激诱导的磷酸化蛋白，参与许多细胞信号通路。CREB和CREB相互作用蛋白的功能障碍和失控会导致癌症和神经变性等人类疾病。CREB似乎在多种组织的细胞防御和生存中发挥关键作用；然而，CREB参与细胞生存的机制以及CREB功能缺失导致这些人类疾病的原因仍不完全清楚。CREB在Ser-133处的磷酸化是主要的翻译后修饰，它增强了CREB的活性，以响应受体偶联刺激。然而，CREB Ser-133的磷酸化状态并不总是与CREB的转录功能相关，这表明与CREB Ser-133磷酸化一起的另一事件似乎以刺激特异性的方式参与了CREB的调控。这项研究可能为这些悬而未决的问题提供证据和关键的答案，因为我们最近发现，HIPK2(同源域相互作用蛋白激酶2)是一种遗传毒性应激反应蛋白，它通过激活一个新的丝氨酸位点(Ser-271)而不是Ser-133来激活CREB，导致CREB转录功能的激活。我们将通过这个新的CREB位点的磷酸化来验证我们的假设，即HIPK2是CREB转录因子的一个新的调节因子，它诱导细胞在遗传毒性和氧化应激条件下的生存程序。这些实验将集中于通过HIPK2磷酸化CREB激活其转录功能的分子机制及其下游事件的表征，包括在体外和体内模型中靶基因的表达和细胞对遗传毒性应激的敏感性。这项研究的科学影响将是广泛和重大的，因为CREB调节基本的细胞事件，如细胞生长、分化、新陈代谢和免疫反应。因此，这一提案的成功完成将加深我们对与CREB活性密切相关的各种生理和疾病情况的理解。 公共卫生相关性：由环境和人造化学品引起的遗传毒性和氧化应激与人类疾病有关，包括癌症和神经退化(如阿尔茨海默病和帕金森病)以及衰老；因此，研究确定针对有害应激的细胞防御机制对于我们理解这些疾病的发病机制、预防和/或延迟具有重要意义。CREB是一种重要的转录因子，在多种细胞类型的细胞新陈代谢、分化、存活和增殖中起着关键作用。事实上，越来越多的证据表明，CREB功能障碍和放松调控会导致癌症和神经细胞损伤。CREB参与了细胞在遗传毒性应激条件下的存活；然而，与CREB在外界刺激中发挥长期作用(如细胞分化和增殖)的特性不同，CREB在有害的遗传毒性和氧化应激条件下调控的分子机制仍然很大程度上未知。这一建议将表征我们最近发现的一种新的CREB调控途径和机制，它不同于先前已知的CREB途径。我们预计，拟议中的实验的成功完成将提高我们对细胞如何在这些应激和疾病条件下诱导CREB调节的细胞生存计划的理解。这项研究将在许多研究领域产生广泛而重大的影响，因为CREB转录因子在不同类型的组织中调节着许多细胞功能。这项研究的创新之处将包括在细胞水平和动物模型中展示新的CREB信号通路和参与应激反应的下游靶基因。

DESCRIPTION (provided by applicant): The CREB (cAMP-response element binding) transcription factor is a stimulus-induced phospho-protein that is involved in numerous cell signaling pathways. Dysfunction and deregulation of CREB and CREB- interacting proteins cause human diseases such as cancer and neurodegeneration. CREB appears to play a key role in cell defense and survival in various tissues; however, the mechanisms through which CREB is involved in cell survival and the reason why deregulation of CREB function causes these human diseases remain incompletely understood. CREB phosphorylation at Ser-133 is the major posttranslational modification that enhances CREB activity in response to receptor-coupled stimuli. However, the status of CREB Ser-133 phosphorylation was not always correlated with CREB transcription function, suggesting that another event along with CREB Ser-133 phosphorylation seems to be involved in CREB regulation in a stimulus-specific manner. This research project may provide evidence and a critical answer to these unsolved problems because we recently found that HIPK2 (homeodomain interacting protein kinase 2), a genotoxic stress responsive kinase, activates CREB via phosphorylation of a new serine site (Ser-271) but not Ser-133, resulting in activation of CREB transcription function. We will test our hypothesis that HIPK2 is a new regulator of the CREB transcription factor via phosphorylation of this new CREB site that induces a cell survival program in genotoxic and oxidative stress conditions. The proposed experiments will focus on characterization of molecular mechanism through which CREB phosphorylation by HIPK2 activates its transcription function as well as downstream events including expression of target genes and cellular susceptibility to genotoxic stress in in vitro and in vivo models. The scientific impact of this research will be broad and significant because CREB regulates essential cellular events such as cell growth, differentiation, metabolism, and immune response. Therefore the unveiled new CREB regulation from successful completion of this proposal will enhance our understanding in various physiological and disease conditions closely associated with the CREB activity. PUBLIC HEALTH RELEVANCE: Genotoxic and oxidative stress induced by environmental and manmade chemicals are associated with human disease including cancer and neurodegeneration (such as Alzheimer and Parkinson's diseases), and aging; therefore, research to determine cellular defense mechanisms against the harmful stress is important for our understanding of the pathogenesis, prevention, and/or delay of these diseases. CREB is an essential transcription factor that plays critical roles in cell metabolism, differentiation, survival, and proliferation in various cell types. Indeed, accumulating evidence indicates that dysfunction and deregulation of CREB cause cancer and neuronal cell damage. CREB is involved in cell survival in genotoxic stress conditions; however, in contrast to intensive characterization of CREB in external stimuli that exert long-term effects such as cell differentiation and proliferation, molecular mechanisms behind CREB regulation in detrimental genotoxic and oxidative stress conditions remain largely unknown. This proposal will characterize a novel CREB regulatory pathway and mechanism we recently found, which are different from of a previously known CREB pathway. We anticipate that successful completion of proposed experiments will improve our understanding of how cells elicit CREB-regulated cell survival program against these stress and disease conditions. The impact of this research will be broad and significant in many research areas because the CREB transcription factor regulates numerous cellular functions in various types of tissues. Innovation of this research will include demonstration of a novel CREB signaling pathway and downstream target genes involved in stress response in cellular levels and an animal model.