Role of Alternative Mxi1 Isoforms in the Myc Network

替代 Mxi1 同工型在 Myc 网络中的作用

基本信息

批准号：
6771668
负责人：
DANIEL STEVEN WECHSLER
金额：
$ 28.2万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2001
资助国家：
美国
起止时间：
2001-07-01 至 2006-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/6771668
关键词：
RNA splicing gene targeting genetic promoter element genetically modified animals laboratory mouse neoplastic growth neuroblastoma oncoproteins protein isoforms protein protein interaction transcription factor

项目摘要

DESCRIPTION: (provided by applicant) The MYC proto-oncogene family plays a central role in the response to mitogenic stimuli and the control of proliferation in normal and malignant cells. c-Myc protein overexpression is a hallmark of Burkitt's lymphoma, and N-MYC amplification is a critical prognostic factor in neuroblastoma. MYC gene expression is also deregulated in many other cancers, but the molecular mechanisms that regulate Myc activity are only partly elucidated. This proposal will specifically investigate the role of Mxii and MxiO, two Myc family members, in modulating the activity of both c- and N-Myc. As a transcription factor, Myc regulates expression of genes related to cell growth, division and apoptosis. In contrast to Myc, Mxii represses transcription of some Myc-regulated genes, counteracting the effects of Myc. Thus, Mxii is a Myc antagonist. We have shown that Mxii expression results in growth arrest, suppressing cell proliferation in vitro. Therefore, we hypothesize that reduced Mxii activity is likely to potentiate Myc-dependent proliferation. We recently identified MxiO, a novel, alternatively transcribed Mxii isoform that lacks the growth suppressive activity of Mxii. While MxiO and Mxii are concomitantly expressed in many cell lines and tissues, the relative levels of MxiO are higher in tumors and tumor cell lines than in normal cells. This variation in levels of MxiO and Mxii suggests that the Myc-inhibitory activity of Mxii may be modulated by MxiO. We postulate that MxiO is an Mxii antagonist. This notion of a single gene giving rise to protein products with alternative biological activities is well established in the case of Bcl-x (Bcl-xL vs. Bcl-xS) and Ink4a (p16 vs. p14). In this proposal, we will explore the interactions of MxiO and Mxil with each other and with Myc, in the context of both cell proliferation and neoplasia, by setting the following Specific Aims: (1) Characterize the biological activity of MxiO; (2) Determine how expression of MxiO and Mxii are coordinately regulated, using our experience with the Mxii promoter to determine the factors that regulate expression through the MxiO promoter; (3) Determine mechanisms of growth regulation by MxiO and Mxii in the context of Myc-we will use models of c-Myc-induced transformation, as well as N-Myc-dependent neuroblastoma proliferation to explore these interactions, and also study patterns of gene expression; and (4) Evaluate the in vivo effects of specifically inactivating mxii or mxiO in transgenic mice. Through these studies, we will gain a better understanding of the role of these Mxii isoforms in the complex Myc signaling pathways involved in cell growth regulation and neoplasia.

描述：（由申请人提供）MYC原癌基因家族发挥着在对有丝分裂刺激的反应和控制中发挥核心作用正常和恶性细胞的增殖。 c-Myc 蛋白过度表达是伯基特淋巴瘤的标志，N-MYC 扩增是关键神经母细胞瘤的预后因素。 MYC 基因表达也失调许多其他癌症，但调节 Myc 活性的分子机制是仅部分阐明。该提案将专门调查 Mxii 和 MxiO 是 Myc 家族的两个成员，可调节 c- 的活性和N-Myc。作为转录因子，Myc 调节相关基因的表达影响细胞的生长、分裂和凋亡。与 Myc 相比，Mxii 抑制一些 Myc 调节基因的转录，抵消 Myc 的影响。因此，Mxii 是 Myc 拮抗剂。我们已经证明 Mxii 表达结果生长停滞，抑制体外细胞增殖。因此，我们假设 Mxii 活性降低可能会增强 Myc 依赖性增殖。我们最近发现了 MxiO，一种新颖的、替代转录的 Mxii 亚型缺乏 Mxii 的生长抑制活性。而 MxiO 和 Mxii 在许多细胞系和组织中同时表达，相对肿瘤和肿瘤细胞系中的 MxiO 水平高于正常细胞。 MxiO 和 Mxii 水平的这种变化表明 Myc 抑制 Mxii 的活性可能受 MxiO 调节。我们假设 MxiO 是 Mxii 对手。这种单一基因产生蛋白质产物的概念 Bcl-x 的替代生物活性已得到充分证实（Bcl-xL 与 Bcl-xS）和 Ink4a（第 16 页与第 14 页）。在本提案中，我们将探讨 MxiO 和 Mxil 之间以及与 Myc 的相互作用，在上下文中细胞增殖和肿瘤形成，通过设置以下具体目的：（1）表征MxiO的生物活性； (2) 确定如何根据我们的经验，MxiO 和 Mxii 的表达得到协调调节与 Mxii 启动子一起确定调节表达的因素通过MxiO启动子； (3) 确定生长调节机制 Myc 背景下的 MxiO 和 Mxii - 我们将使用 c-Myc 诱导的模型转化以及 N-Myc 依赖性神经母细胞瘤增殖探索这些相互作用，并研究基因表达模式；和（4）评估特异性灭活 mxii 或 mxiO 的体内效果转基因小鼠。通过这些研究，我们将更好地了解这些 Mxii 异构体在复杂的 Myc 信号通路中的作用细胞生长调节和肿瘤形成。