Molecular Regulation of Erythroid Differentiation

描述(申请人提供)：在哺乳动物的红细胞生成过程中，红系祖细胞分化为红母细胞，随后去除细胞核和细胞器以发育为成熟的红细胞。尽管与红细胞生成不同阶段相关的形态变化已经被很好地描述，但控制这些过程的确切分子机制仍有待确定。已发现Bcl2家族成员Nix/Bnip3L在红系细胞分化过程中调节线粒体清除。在Nix缺乏的红细胞中，自噬小体的形成正常进行。然而，线粒体到自噬体内的隔离是有缺陷的。实验旨在验证这样一种假设：在红系终末分化过程中，Nix调节线粒体靶向自噬小体进行清除，而由于线粒体自噬缺陷而导致线粒体异常保留的红细胞容易受到氧化应激，导致细胞周转率增加和溶血性贫血。目的1.利用NIX缺陷小鼠或自噬缺陷小鼠和红白血病细胞系，研究NIX是线粒体自噬所必需的假说，而不是红系成熟的其他方面。目的2.研究线粒体自噬缺陷的红细胞是否对氧化应激诱导的细胞凋亡更敏感。目的3.用免疫沉淀和蛋白质组学方法研究介导Nix诱导的线粒体自噬的下游分子。红系成熟缺陷已被发现与贫血有关。通过确定线粒体自噬在红系成熟过程中负责线粒体移除的分子调控，我们将深入了解在正常和疾病环境下红细胞生成的调控。这将有助于更好地了解与红系成熟缺陷相关的血液学疾病的发病机制。它还可能促进治疗这些疾病的治疗方法的发展。公共卫生相关性：该项目旨在研究红系成熟过程中线粒体自噬的分子调控。这将有助于深入了解在正常和疾病环境下红细胞生成的调节。建议的研究可能有助于更好地理解与红系成熟缺陷相关的血液学疾病的发病机制。

DESCRIPTION (provided by applicant): During mammalian erythropoiesis, erythroid progenitors differentiate into erythroblasts, followed by the removal of the nucleus and organelles to develop into mature erythrocytes. Although the morphological changes associated with different stages of erythropoiesis have been well characterized, the precise molecular mechanisms governing these processes remain to be determined. A Bcl-2 family member, Nix/Bnip3L, has been found to regulate mitochondrial clearance in differentiating erythroid cells. In Nix-deficient red blood cells, the formation of autophagosomes proceeded normally. However, the sequestration of mitochondria into autophagosomes was defective. Experiments are proposed to test the hypothesis that Nix regulates the targeting of mitochondria into autophagosomes for clearance during terminal erythroid differentiation, and erythrocytes with abnormal retention of mitochondria due to defective mitochondrial autophagy are prone to oxidative stress, leading to increased cell turnover and hemolytic anemia. Aim 1. The hypothesis that Nix is required for the mitochondrial autophagy, but not other aspects of erythroid maturation, will be studied using mice deficient in Nix or autophagy and erythroleukemic cell line. Aim 2. Whether erythrocytes deficient in mitochondrial autophagy are more susceptible to oxidative stress-induced apoptosis will be examined. Aim 3. Downstream molecules mediating Nix-induced mitochondrial autophagy will be studied using immunoprecipitation and proteomics approach. Defects in erythroid maturation have been found to be associated with anemia. By determining the molecular regulation of mitochondrial autophagy responsible for mitochondrial removal during erythroid maturation, we will gain insights into the regulation of erythropoiesis under both normal and disease settings. This will lead to better understanding of the pathogenesis of hemotological disorders associated with defective erythroid maturation. It may also facilitate the development of therapeutic approaches to treat these disorders. PUBLIC HEALTH RELEVANCE: This project seeks to investigate molecular regulation of mitochondrial autophagy during erythroid maturation. This will help gain insights into the regulation of erythropoiesis under both normal and disease settings. The proposed studies may lead to better understanding of the pathogenesis of hemotological disorders associated with defective erythroid maturation.