ELUCIDATING THE ROLE OF KRUPPEL LIKE FACTOR 7 IN T CELL DEVELOPMENT

描述（由申请人提供）：本申请提出了一个4年计划，为候选人提供指导研究和职业发展培训。候选人最近完成了为期3年的K12奖（儿科科学家发展计划），并希望获得额外的指导支持，以促进她的科学和职业目标。的最终目标 候选人是一个独立的调查员在学术医疗中心，研究因素，调节正常和恶性造血。本申请中概述的实验旨在了解转录因子Kruppel样因子7（KLF 7）在T细胞发育中的作用。拟议的研究将在华盛顿大学进行，主要由丹尼尔林克博士指导，他是造血领域的领导者，也是一位经验丰富、备受尊敬的导师。由于拟议的研究是候选人研究的新途径，胸腺细胞发育专家Takeshi Egawa博士将担任共同导师，并提供T细胞研究的技术指导。KLF 7的表达在治疗耐药的儿科ALL中增加，并且是复发性疾病的独立预测因子（Flotho，et al; Blood 2007）。KLF家族的转录因子参与血细胞发育的许多方面;然而，KLF 7在造血中的作用先前尚未描述。由于KLF 7靶基因包括几个与造血干细胞和祖细胞（HSPC）维持有关的基因，我们假设KLF 7可能在调节正常HSPC功能中发挥作用，并可能导致白血病发生或治疗耐药性。我们在初步数据中显示，KLF 7的增强表达，同时显著抑制HSC的再增殖和自我更新能力，导致T细胞的相对保存，抗凋亡因子BCL 2A 1的表达增加，以及CD 4-CD 8-（DN）胸腺细胞的凋亡减少。KLF 7在整个T细胞发育过程中表达，在胸腺细胞发育的CD 4 + CD 8+（DP）阶段达到峰值。KLF 7的缺失与早期胸腺细胞数量的减少有关。基于我们的初步数据和KLF家族在调节T细胞中的突出作用，我们假设KLF 7调节胸腺细胞发育和向T细胞谱系的定型。此外，KLF 7的过表达抑制早期胸腺细胞的凋亡，并可能导致ALL的化疗耐药性。提出的具体目标是：1）确定KLF 7是否指导多能祖细胞向T细胞命运的定型;和2）确定KLF 7对胸腺细胞存活、增殖和成熟的贡献。此外，我们建议确定KLF 7在胸腺细胞中的靶点，并进一步阐明BCL 2A 1在介导过度表达KLF 7的DN胸腺细胞存活中的作用。未来的研究将调查所确定的靶点在T细胞发育中的作用，并可能介导白血病细胞的治疗抗性。最终，抑制KLF 7或其下游靶点可潜在地用于敏化化疗抗性细胞，从而提供治疗难治性或复发性白血病的靶向方法。

DESCRIPTION (provided by applicant): This application proposes a 4-year plan to provide the candidate with mentored research and career development training. The candidate has recently completed a 3-year K12 award (Pediatric Scientist Development Program), and desires additional mentored support to facilitate her scientific and career goals. The ultimate goal of the candidate is to be an independent investigator at an academic medical center, studying factors that regulate normal and malignant hematopoiesis. The experiments outlined in this application aim to understand the role of the transcription factor Kruppel like factor 7 (KLF7) in T cell development. The proposed studies will be carried out at Washington University under the primary mentorship of Dr. Daniel Link, a leader in the field of hematopoiesis and a highly experienced and regarded mentor. As the proposed studies are a new avenue of study for the candidate, Dr. Takeshi Egawa, an expert in thymocyte development, will serve as a co-mentor and provide technical guidance on the study of T cells. Expression of KLF7 is increased in therapy-resistant pediatric ALL and is an independent predictor of relapsed disease (Flotho, et al; Blood 2007). The KLF family of transcription factors is involved in numerous aspects of blood cell development; however a role for KLF7 in hematopoiesis has not been previously described. Since KLF7 target genes include several implicated in hematopoietic stem and progenitor (HSPC) maintenance, we hypothesized that KLF7 may play a role in regulating normal HSPC function, and may contribute to leukemogenesis or therapy resistance. We show in preliminary data that enforced expression of KLF7, while markedly inhibiting HSC repopulating and self-renewal capacities, results in the relative preservation of T cells, increased expression of the anti-apoptotic factor BCL2A1, and reduced apoptosis of CD4- CD8-(DN) thymocytes. KLF7 is expressed throughout T cell development, peaking at the CD4+ CD8+ (DP) stage of thymocyte development. Loss of KLF7 is associated with decreased numbers of early thymocytes. Based on our preliminary data and the prominent role of the KLF family in regulating T cells, we hypothesize that KLF7 regulates thymocyte development and commitment to the T cell lineage. Furthermore, overexpression of KLF7 suppresses apoptosis of early thymocytes and may contribute to chemotherapy resistance in ALL. The specific aims proposed are: 1) Determine whether KLF7 directs the commitment of multipotent progenitor cells to a T cell fate; and 2) Determine the contribution of KLF7 to thymocyte survival, proliferation and maturation. In addition, we propose to identify targets of KLF7 in thymocytes, and to further elucidate the role of BCL2A1 in mediating the survival of DN thymocytes overexpressing KLF7. Future studies will investigate the role of the identified targets in T cell development and in potentially mediating the therapy-resistance of leukemia cells. Ultimately, inhibition of KLF7 or its downstream targets could potentially be used to sensitize chemotherapy- resistant cells, providing a targeted approach to the treatment of refractory or relapsed leukemia.