DYRK1A signaling in control of cell growth, proliferation and DNA damage repair

描述(由申请人提供)：细胞抑制增殖和进入G1期或G0期(静止)状态的能力对肿瘤抑制至关重要。视网膜母细胞瘤(retinoblastoma，RB)家族蛋白，包括p130，通过尚未完全了解的机制介导哺乳动物细胞G0/G1期停滞。进入G0/G1后，p130被招募到DNA结合的DREAM蛋白复合体(DP、RB样蛋白、E2F和MuvB核心)。5种蛋白(LIN9、LIN37、LIN52、LIN54和RBBP4)的MuvB核心在转录调控中起双重作用。当MuvB核心与G0/G1中的p130结合时，形成梦想复合体，并抑制800多个细胞周期依赖基因。当从DREAM释放时，MuvB核心与BMYB结合，激活有丝分裂基因。DYRK1A蛋白激酶通过磷酸化LIN52亚基在促进DREAM复合体的组装方面发挥关键作用，LIN52亚基是p130和MuvB核心之间结合所必需的。对DYRK1A的抑制足以阻止DREAM复合体的组装，并推翻G0/G1期的抑制。DYRK1A基因被定位到唐氏综合症(DS)的关键区域，其由于21三体而上调，导致DS患者的精神障碍。确定DYRK1A在肿瘤抑制中的作用非常重要，因为它作为改善DS患者认知功能的潜在靶点具有潜在的价值。以往的研究表明，DYRK1A在Rb家族介导的G0/G1期停滞以及RAS诱导的致癌衰老中起着重要作用。此外，生化数据表明，在河马肿瘤抑制途径中，DYRK1A位于LATS2激酶的下游。我们的初步分析发现，DYRK1A基因在高级别卵巢癌中发生频繁的拷贝数丢失，提示DYRK1A基因的失活参与了卵巢癌的发病机制。我们推测，在卵巢癌中，由于基因缺失或异常调节(如LATS介导的激活缺失)导致的DYRK1A失活可能通过扰乱梦想复合体的组装和功能而促进卵巢癌的发生。我们建议使用以下策略通过描述细胞中的DYRK1A通路来检验这一假说。目的1，探讨DYRK1A基因缺失是否促进卵巢癌前体细胞的恶性转化，以及DYRK1A功能增强是否能抑制卵巢癌的体内外生长。在目标2中，我们将确定河马通路在调节DYRK1A和梦境复合体中的作用。由于DYRK1a在细胞中的功能和调控还不完全清楚，我们鉴定了DYRK1a相互作用的蛋白质。在目标3中，我们将根据DYRK1A在发育和癌症中的潜在意义来鉴定新的DYRK1A相互作用蛋白，并建立这些因子在DYRK1A生长抑制功能中的作用。DYRK1A调控通路的生化和功能特征将促进我们对静止期的认识，提高我们对卵巢癌发病机制的理解，并确定DYRK1A是否可以安全地靶向治疗DS。

DESCRIPTION (provided by applicant): The ability of cells to arrest proliferation and to enter a G1-arrested or G0 (quiescent) state is critical for tumor suppression. Retinoblastoma (RB) family proteins, including p130, mediate G0/G1 arrest in mammalian cells by mechanisms that are not fully understood. Upon entry into G0/G1, p130 is recruited into the DNA-binding DREAM protein complex (DP, RB-like, E2F, and MuvB core). The MuvB core of 5 proteins (LIN9, LIN37, LIN52, LIN54, and RBBP4) plays a dual role in transcriptional control. When bound to p130 in G0/G1, the MuvB core forms the DREAM complex and represses more than 800 cell cycle-dependent genes. When released from DREAM, the MuvB core binds to BMYB to activate mitotic genes. DYRK1A protein kinase plays a critical role in promoting assembly of the DREAM complex by phosphorylating the LIN52 subunit, which is required for binding between the p130 and MuvB core. Inhibition of DYRK1A is sufficient to block assembly of the DREAM complex and to override G0/G1 arrest. The DYRK1A gene is mapped to a Down syndrome (DS) critical region, and its upregulation due to trisomy 21 contributes to mental impairment in people with DS. It is important to establish the role of DYRK1A in tumor suppression because of its potential value as a therapeutic target to improve the cognitive functions of people with DS. Previous studies have revealed an essential role of DYRK1A in G0/G1 arrest, mediated by RB family, as well as in oncogenic Ras-induced senescence. Furthermore, biochemical data suggest that DYRK1A is downstream of LATS2 kinase in the Hippo tumor suppressor pathway. Our preliminary analysis found that the DYRK1A gene undergoes frequent copy number loss in high-grade ovarian carcinoma, suggesting that inactivation of DYRK1A contributes to the pathogenesis of ovarian cancer. We hypothesize that inactivation of DYRK1A in ovarian cancer due to genetic losses or aberrant regulation (such as loss of LATS-mediated activation) could promote ovarian carcinogenesis by disrupting the assembly and function of the DREAM complex. We propose to test this hypothesis by characterizing DYRK1A pathways in cells using the following strategy. In Aim 1, we will determine whether loss of DYRK1A contributes to the malignant transformation of the ovarian cancer precursor cells and whether gain of DYRK1A function can suppress the growth of ovarian cancers in vitro and in vivo. In Aim 2, we will determine the role of the Hippo pathway in regulating DYRK1A and the DREAM complex. Since the function and regulation of DYRK1A in cells is not fully understood, we identified DYRK1A-interacting proteins. In Aim 3, we will characterize novel DYRK1A-interacting proteins that have been prioritized by their potential significance in development and cancer, and establish the role of these factors in the growth arrest functions of DYRK1A. The proposed biochemical and functional characterization of DYRK1A-regulated pathways will advance our knowledge of quiescence, improve our understanding of the pathogenesis of ovarian cancer, and establish whether DYRK1A can be safely targeted to treat DS.