Investigating the role of DUX and miR-34a regulation in cell fate plasticity and cancer

项目摘要 被劫持的细胞命运潜力的可塑性，与致癌突变相结合，推动恶性转化和 在许多癌症中存在治疗耐药性。全能性-细胞变成完全胚胎和超常的能力- 胚胎组织-代表哺乳动物胚胎/干细胞命运潜力的高度。DUX是双打 同源结构域转录因子在B细胞急性淋巴细胞白血病亚群中错误表达 圆形细胞肉瘤。我们的实验室最近将DUX(小鼠DUX/人DUX4)定义为全能的主要驱动因素 小鼠和人类的发育计划。多能小鼠胚胎干细胞的表达 小鼠DUX被有效地转换成一种类似2C的全能状态，这种状态在表观遗传和转录上都是 类似于2-细胞小鼠胚胎。在体内，Dux的表达是高度瞬时的，持续时间不到一个细胞周期 在早期胚胎中。尽管全能的转录组已经被很好地研究了，但胚胎如何利用尚不清楚。 DUX下游的转录后和翻译调控，以建立这种细胞命运的可塑性，以及 是什么机制随后限制了发育潜力，以确保适当的血统确定。 最近，我们和其他人发现了P53在DUX激活中的核心作用。P53是一种主要的肿瘤 抑制因子和转录因子，它也激活microRNA(MiRNA)34家族(a/b/c)作为反应 造成DNA损伤。Mir-34a在许多小鼠和人类组织中都有表达，是一种研究得很好的肿瘤。 抑制因子本身，抑制参与细胞生长和增殖的途径。重要的是，miR-34a缺失 在mESCs中，它们很有可能转变为全能状态，但其机制 控制这种扩大的细胞命运的可塑性尚不清楚。我们发现mESCs中miR-34a的缺失是 DUX转录本的积累，DUX4在其3‘UTR中包含一个预测的miR-34a靶点，表明 MiR-34a的直接调控作用。我们假设P53和miR-34a激活和抑制Dux(和/或Dux 靶)，分别形成调节全能性网络并最终限制 体内细胞命运可塑性。揭示安全守护细胞命运潜力的机制和预防 体内致癌将在癌症生物学和再生医学方面产生新的见解。我是唯一的 准备在加州大学亨茨曼癌症研究所的凯恩斯实验室回答这些问题 犹他州。利用我们先进的DUX专业知识，结合与翻译领域专家的关键协作 控制，我有信心我有能力执行这项提案中概述的实验。此外，我的 优秀的临床导师团队，由高效的内科和外科科学家组成，将促进 我的临床发展，因为我试图将细胞命运可塑性的分子驱动因素和 肿瘤发生发展成为癌症治疗和再生医学的新靶点。

Project Summary Hijacked plasticity of cell fate potential, combined with oncogenic mutations, drives malignant transformation and therapeutic resistance in many cancers. Totipotency – the ability of a cell to become all embryonic and extra- embryonic tissues – represents the height of embryonic/stem cell fate potential in mammals. DUX is a double homeodomain transcription factor that is misexpressed in subsets of B-cell acute lymphoblastic leukemia and round-cell sarcomas. Our lab recently defined DUX (mouse Dux / human DUX4) as a major driver of totipotent developmental programs in mouse and human. Pluripotent mouse embryonic stem cells (mESCs) expressing mouse Dux are potently converted into a ‘2C-like’ totipotent state, which epigenetically and transcriptionally resemble the 2-cell mouse embryo. In vivo, DUX expression is highly transient, and lasts less than a cell cycle in early embryos. Although the transcriptome of totipotency is well studied, it is unclear how the embryo employs post-transcriptional and translational regulation downstream of DUX to establish this plasticity in cell fate, and what mechanisms subsequently restrict developmental potency to ensure proper lineage determination. Recently, we and others have discovered a central role for p53 in DUX activation. P53 is a master tumor suppressor and transcription factor, which also activates the micro-RNA (miRNA) 34 family (a/b/c) in response to DNA damage. miR-34a is expressed in many mouse and human tissues, and is a well-studied tumor suppressor itself, repressing pathways involved in cellular growth and proliferation. Importantly, miR-34a deletion in mESCs confers a high probability of their conversion into a totipotent state, however the mechanisms governing this expanded cell fate plasticity are unclear. We find that loss of miR-34a in mESCs causes accumulation of Dux transcripts, and DUX4 contains a predicted miR-34a target site in its 3’ UTR, suggesting a direct regulatory role of miR-34a. We hypothesize that p53 and miR-34a activate and repress Dux (and/or Dux targets), respectively, forming a feedback loop which regulates the totipotency network and ultimately restricts cell fate plasticity in vivo. Uncovering the mechanisms safe-guarding cell fate potential and preventing oncogenesis in vivo will yield novel insights in both cancer biology and regenerative medicine. I am uniquely positioned to answer these questions in the Cairns Lab within the Huntsman Cancer Institute at the University of Utah. Leveraging our advanced DUX expertise, combined with key collaborations with experts in translational control, I am confident in my abilities to execute the experiments outlined within this proposal. Additionally, my excellent clinical mentorship team, crafted from highly productive physician- and surgeon-scientists, will promote my clinical development as I seek to combine key insights from molecular drivers of cell fate plasticity and oncogenesis into development of novel targets for cancer therapeutics and regenerative medicine.