Mitochondrial matrix-localized MCL-1 regulates hematopoietic stem cell self-renewal and regeneration

项目摘要/摘要 造血干细胞的自我更新和多向分化的调控 对终生维持造血至关重要的，尤其是在造血压力或 移植。HSC再生活性的缺陷会导致免疫缺陷、贫血和 增加了对髓系恶性肿瘤的易感性。HSC通常处于静止状态，但可以自我更新 它们必须进入细胞周期。这与线粒体氧化代谢的激活有关。 因此，了解HSC的静止和增殖是如何被调控的，将为我们提供关于如何 在衰老、造血应激或移植过程中，HSC的功能可以维持。 我们已经证明MCL-1是正常造血和HSC存活的重要介质。 在从压力中恢复时。这些功能在外部与MCL-1‘S促生存功能有关 线粒体膜；然而，MCL-1也可以被输入到线粒体基质中，在那里 调节线粒体新陈代谢和分裂/融合动力学。我们已经培育出一只突变的小鼠 表达截短的MCL-1蛋白(MCL-1OMM)，可阻止细胞凋亡，但不能导入 线粒体基质。当受到清髓性应激时，Mcl10-OMM小鼠表现出再生缺陷和 大多数动物都会死亡。此外，来自mcl100小鼠的骨髓细胞表现出深刻的竞争性 在移植实验中处于劣势。 我们的中心假设是基质定位的MCL-1调节线粒体动力学和呼吸。 促进其自我更新能力和促进从压力中恢复的造血干细胞。以下目标将检验这一点 假设：目的1：分析线粒体基质MCL-1缺失小鼠的HSC表型/功能。目标2： 确定缺乏线粒体基质-MCL-1如何影响线粒体动力学和氧化 磷酸化。目的3：探讨基质-MCL-1的强制表达是否促进HSC功能。 我的实验室已经取得了许多开创性的发现，确定了MCL-1在促进生存方面的作用 正常的造血和白血病患者。我们处于得天独厚的地位，能够成功地进行这些研究 我们已经生成了关键的、新颖的模型系统，这将使我们能够在以下位置从功能上剖析MCL-1的S函数 线粒体。在这项研究的最后，我们将阐明以前未被认识到的mcl1在 调节HSC功能。

PROJECT SUMMARY/ABSTRACT The regulation of self-renewal and multi-lineage differentiation of hematopoietic stem cells (HSCs) is essential for lifelong maintenance of hematopoiesis, especially under conditions of hematopoietic stress or transplantation. Defects in HSC repopulating activity contribute to immune deficiencies, anemia, and an increased susceptibility to myeloid malignancies. HSCs typically exist in a quiescent state, but to self-renew they must enter the cell cycle. This is associated with an activation of mitochondrial oxidative metabolism. Thus, understanding how HSC quiescence and proliferation are regulated will provide key insights into how HSC function can be maintained in aging, under conditions of hematopoietic stress, or during transplantation. We have demonstrated that MCL-1 is an essential mediator of HSC survival in normal hematopoiesis and during recovery from stress. These functions are associated with MCL-1's pro-survival function on the outer mitochondrial membrane; however, MCL-1 can also be imported into the mitochondrial matrix where it regulates mitochondrial metabolism and fission/fusion dynamics. We have generated a mutant mouse that expresses a truncated MCL-1 protein (MCL-1OMM) which blocks apoptosis, but cannot be imported into the mitochondrial matrix. When subjected to myeloablative stress, Mcl1OMM mice exhibit defective regeneration and most animals die. Furthermore, bone marrow cells from the Mcl1OMM mice exhibit a profound competitive disadvantage in transplantation experiments. Our central hypothesis is that matrix-localized MCL-1 regulates mitochondrial dynamics and respiration in HSCs promoting their ability to self-renew and promote recovery from stress. The following aims will test this hypothesis: Aim 1: Analyze the HSC phenotype/function from mice lacking mitochondrial matrix-MCL-1. Aim 2: Determine how lack of mitochondrial matrix-MCL-1 affects mitochondrial dynamics and oxidative phosphorylation. Aim 3: Interrogate whether enforced expression of matrix-MCL-1 promotes HSC function. My laboratory has made many seminal findings defining the role of MCL-1 in promoting survival during normal hematopoiesis and in leukemia. We are uniquely positioned to successfully perform these studies as we have generated critical, novel model systems that will allow us to functionally dissect MCL-1's functions at the mitochondria. At the end of this study, we will illuminate a previously unrecognized role for MCL-1 in regulating HSC function.