Investigation into the role of autophagy protease ATG4A in normal and impaired erythropoiesis

项目摘要/摘要 自噬是一种自我降解途径，在红细胞生成中具有组织特异性功能。在红系期间 分化，自噬促进大分子的降解和程序性清除 线粒体。这项提案的长期目标是确定自噬如何有助于正常和 红细胞生成受损。骨髓增生异常综合征(MDS)患者通常有红细胞生成障碍 和线粒体功能障碍。MDS的一个子集，即具有环状铁粒母细胞(RS)的MDS，包含这种异常 红细胞中富含铁的线粒体的积聚表明自噬可能在 造血功能障碍，并损害红系分化。虽然已知必要的自噬基因 对于自噬在红细胞生成中的作用，对自噬的组织特异性调控知之甚少。 人类红系分化。我们已经鉴定了自噬蛋白酶ATG4A的选择性表达 在红系血统中。我们评估了ATG4A在人红系体外模型中的作用 差异化。在分化早期，ATG4A促进红系的扩增和集落形成 祖先。在分化后期，ATG4A促进终末成熟、去核和线粒体 通行证。由于ATG4蛋白水解酶受活性氧的调节，ATG4A在 红细胞生成可能对氧化应激很敏感。根据我们的初步结果，我们假设 ATG4A在早期和晚期的红细胞生成中介导自噬，并受到氧化应激的失调。在AIM 1，我们将确定ATG4A依赖的自噬在早期红细胞生成中的作用。在目标2中，我们将确定 ATG4A依赖的线粒体清除机制。在目标3中，我们将研究对 人类MDS-RS模型的线粒体清除。这项提案中概述的实验将是 在谢尔盖·杜拉托夫博士的指导下进行，他是开发和使用人类IPSC的专家 研究红系疾病的模型，以及雅尼斯·阿布科维茨博士的共同指导 华盛顿大学的血液学专家，MDS和红系生物学的国际专家。这份职业 发展奖将支持我成为一名独立调查员，研究 对正常和功能失调的红细胞生成的自噬作用。

PROJECT SUMMARY/ ABSTRACT Autophagy is a self-degradation pathway that has tissue-specific functions in erythropoiesis. During erythroid differentiation, autophagy facilitates the degradation of macromolecules and the programmed clearance of mitochondria. The long-term objective of this proposal is to determine how autophagy contributes to normal and impaired erythropoiesis. Patients with Myelodysplastic syndromes (MDS) often have impaired erythropoiesis and mitochondrial dysfunction. A subset of MDS, MDS with ring sideroblasts (RS), contain the aberrant accumulation of iron-laden mitochondria in erythroblasts suggesting that autophagy may be dysregulated in hematopoietic disorders and impair erythroid differentiation. While essential autophagy genes are known to contribute to autophagy in erythropoiesis, little is known about the tissue-specific regulation of autophagy during human erythroid differentiation. We have identified the selective expression of the autophagy protease ATG4A in the erythroid lineage. We have evaluated the contribution of ATG4A in an ex vivo model of human erythroid differentiation. Early in differentiation, ATG4A promotes the expansion and colony formation of erythroid progenitors. Late in differentiation, ATG4A promotes terminal maturation, enucleation, and mitochondrial clearance. Since ATG4 proteases are regulated by reactive oxygen species, the function of ATG4A in erythropoiesis may be sensitive to oxidative stress. Based on our preliminary results, we hypothesize that ATG4A mediates autophagy during early and late erythropoiesis and is dysregulated by oxidative stress. In aim 1, we will identify the role of ATG4A-dependent autophagy in early erythropoiesis. In aim 2, we will determine the mechanism of ATG4A-dependent mitochondrial clearance. In aim 3, we will examine the regulation of mitochondrial clearance in human models of MDS-RS. The experiments outlined in this proposal will be conducted under the mentorship of Dr. Sergei Doulatov, an expert in the development and use of human iPSC models to study erythroid disorders, and co-mentorship of Dr. Janis Abkowitz, Chair of the Division of Hematology at the University of Washington and international expert in MDS and erythroid biology. This career development award will support my training to become an independent investigator studying the contribution of autophagy to normal and dysfunctional erythropoiesis.