Mechanism of action of Prdm16 in hematopoietic stem cells

描述（由申请人提供）：造血干细胞（hsc）可以自我更新并产生造血系统的所有谱系。尽管我们对造血干细胞自我更新、分化和静止机制的理解取得了重大进展，但这些机制如何协同作用以调节体内造血系统的稳态反应的连贯图景尚未出现。一些转录调节因子作为白血病融合蛋白的合作伙伴在HSC生物学中起着关键作用。我们使用种系Prdm16-/-小鼠发现，Prdm16是一种140kDa的锌指蛋白，最初在急性髓母细胞白血病（AML）的一些移位中被发现为融合伙伴，在发育期间和移植后对造血干细胞的建立和维持至关重要。本课题拟进一步分析Prdm16在造血干细胞生物学中的功能，并确定其作用机制。我们的初步数据强烈表明Prdm16在维持线粒体功能和完整性方面的作用，特别是在造血干细胞中。Prdm16以两种剪接形式出现。短(s) Prdm16缺少n端PR结构域。这种剪接变异体通过易位、启动子低甲基化或逆转录病毒插入PR结构域而在白血病中过度表达。我们的初步数据表明，sPrdm16主要负责prdm16缺陷小鼠的造血表型。具体目的如下：目的1：确定HSC功能所需Prdm16的关键发育窗口期；目的2：检测Prdm16-/-造血干细胞和mef的代谢、线粒体功能和动力学；目的3：研究sPrdm16与flPrdm16在HSC维持中的作用。

DESCRIPTION (provided by applicant): Hematopoietic stem cells (HSCs) can self renew and generate all lineages of the hematopoietic system. Despite significant progress in our understanding of mechanisms involved in self-renewal, differentiation and quiescence of HSCs, a coherent picture of how these mechanisms act in concert to regulate homeostatic responses of the hematopoietic system in vivo has not emerged yet. Several transcriptional regulators involved as partners of leukemogenic fusion proteins play a critical role in HSC biology. We found, using germline Prdm16-/- mice, that Prdm16, a 140kDa zinc finger protein that was originally discovered as a fusion partner in some translocations in acute myeloblastic leukemia (AML), is essential for the establishment and maintenance of HSCs during development and after transplantation. In this proposal we want to further analyze the function of Prdm16 in the biology of HSCs, and determine its mechanism of action. Our preliminary data strongly suggest a role for Prdm16 in maintaining mitochondrial function and integrity specifically in HSCs. Prdm16 occurs in two splice forms. Short (s) Prdm16 lacks the N-terminal PR domain. This splice variant is typically overexpressed in leukemias through translocation, promoter hypomethylation, or retroviral insertion into the PR domain. Our preliminary data indicate that primarily sPrdm16 is responsible for the hematopoietic phenotype of Prdm16-deficient mice. The specific aims are the following: Aim 1: To determine the critical developmental window of Prdm16 requirement for HSC function; Aim 2: To examine metabolism, mitochondrial function, and dynamics in Prdm16-/- HSCs and MEFs; Aim 3: To examine the roles of sPrdm16 vs. flPrdm16 in HSC maintenance.