Functions of the TG-Interacting Transcription Factor (TGIF) in Hematopoiesis

我们发现干细胞表达的转录抑制因子定量表达， 转化生长干扰因子（Transforming-growth-interfering factor，TGIF）是目前最具鉴别力和最强的肿瘤预后预测因子。 急性髓细胞性白血病（AML）的生存率。较低水平的TGIF与较短的 生存期，而更高的水平预测更长的生存期（p=0.00001）。为了理解 在我们的临床发现中，我们研究了TGIF在骨髓祖细胞系和Tg/f敲除中的功能。 小鼠模型TGIF在髓系祖细胞系如HL 60中的敲低导致显著的生长， 抑制、相对分化阻滞和髓系转录程序的破坏。分析 在Tg/7缺失小鼠中的造血干细胞（HSC）功能显示，HSC产生较少的集落， 形成单位，并在竞争性移植研究中与野生型HSC相比具有生长优势。 这些数据表明，Tg/f敲除可能会改变HSC关键的静止功能之间的平衡， 分化和自我更新。因此，我们假设Tgif在HSC中起着重要的调节作用， 功能，并将通过1）更彻底地定义Tgif'm HSC的作用， 祖细胞功能; 2）确定Tgif对HSC的作用的细胞基础;和3）确定Tgif对HSC的作用。 Tgif对HSC作用的分子基础。这些目标将通过一系列实验来实现， 各种标准和最先进的分子技术，包括有限稀释竞争性 再增殖分析、连续移植、体内细胞周期分析和结构-功能 使用天然存在的TGIF突变和离体HSC转导进行表征。除了有 Tgif敲除模型，我们还将采用一种新的条件性Tgif敲除等位基因， 为我们的实验设计提供了极大的灵活性。 该提案还概述了一个计划，旨在帮助候选人发展一个成功的职业生涯在学术 药候选人拥有博士学位。在微生物学和免疫学从范德比尔特大学， 完成了儿科住院医师培训和遗传学奖学金培训。候选人将扩大他的 在斯蒂芬·勃兰特和斯科特博士的指导下， 希伯特指导委员会将定期提供额外的指导。 相关性（参见说明）： 在急性白血病，包括AML，静止，自我更新和分化之间的正常平衡 的HSC被破坏。我们的初步数据表明，Tgif可能调节这种平衡，它也有一个 作为AML预后指标的临床作用。因此，我们对Tgif如何调节关键HSC的研究 这些功能将为HSC生物学提供新的见解，并增加我们对AML的理解。 发病机制，从而更好地诊断和治疗这种毁灭性的疾病。

We have discovered that quantitative expression of the stem cell expressed transcriptional represser Transforming-growth-interfering factor (TGIF) is the most discriminating and powerful predictor of patient survival identified in acute myelogenous leukemia (AML). Lower levels of TGIF correlated with shorter survival, whereas higher levels predicted longer survival (p=0.00001). To understand the biological basis for our clinical finding, we investigated TGIF's function in myeloid progenitor cell lines and in a Tg/'f knockout mouse model. TGIF knockdown in myeloid progenitor cell lines, such as HL60, resulted in significant growth inhibition, a relative differentiation block, and disruption of the myeloid transcription program. Analysis of hematopoietic stem cell (HSC) function in Tg/7-null mice showed that the HSCs produced fewer colony- forming units and had a growth advantage compared to wild-type HSCs in competitive transplant studies. These data suggest that Tg/f knockout may alter the balance between the key HSC functions of quiescence, differentiation and self-renewal. We thus hypothesize that Tgif plays a fundamental regulatory role in HSC function and will examine this hypothesis by 1) defining more thoroughly the role of Tgif'm HSC and progenitor cell function; 2) determining the cellular basis of Tgif's effects on HSCs; and 3) determining the molecular basis of Tgif's effects on HSCs. These aims will be carried out in a series of experiments using a variety of standard and state-of-the-art molecular techniques, including limiting dilution competitive repopulation analysis, serial transplantation, in vivo cell cycle analysis, and structure-function characterizations using naturally occurring TGIF mutations and ex vivo HSC transduction. In addition to the Tgif knockout model currently in use, we will also employ a new conditional Tgif knockout allele, which will offer us great flexibility in our experimental design. This proposal also outlines a plan designed to help the candidate develop a successful career in academic medicine. The candidate has a Ph.D. in Microbiology and Immunology from Vanderbilt University and has completed residency training in Pediatrics and fellowship training in Genetics. The candidate will expandhis knowledge of hematopoiesis and leukemogenesis under the mentorship of Drs. Stephen Brandt and Scott Hiebert. A mentoring committee will provide added guidance at regular intervals. RELEVANCE (See instructions): In acute leukemias, including AML, the normal balance between quiescence, self-renewal and differentiation of HSCs is disrupted. Our preliminary data suggest that Tgif may regulate this balance and that it also has a clinical role as a prognostic indicator in AML. Thus, our investigations of how Tgif regulates key HSC functions will provide new insights into HSC biology as well as increase our understanding of AML pathogenesis, leading to better diagnosis and treatment of this devastating disease.