Yang Ran, Yu Donglin, Ren Jiuqiang, Yin Jiaying, Li Jing, Liu Xuehui, Lv Xiang
State Key Laboratory of Complex, Severe, and Rare Diseases, Haihe Laboratory of Cell Ecosystem, Department of Pathophysiology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
FASEB J. 2025 Jun 15;39(11):e70695. doi: 10.1096/fj.202500228R.
The expression of the transmembrane protein CD44 gradually declines during terminal erythropoiesis, marking the differentiating stages of erythroblasts. Despite its significance, the specific role and functional mechanisms of CD44 in erythropoiesis remain poorly understood. In this study, we found that CD44 knockout (CD44KO) mice displayed bone marrow dyserythropoiesis and an exacerbation of phenylhydrazine-induced hemolytic anemia. Single-cell sequencing analysis revealed activated endoplasmic reticulum (ER) stress in CD44KO erythroblasts. Specifically, the PERK/eIF2α/ATF4/CHOP pathway was upregulated, accompanied by enhanced autophagy and subsequent cell apoptosis. Mechanistically, CD44 deficiency suppressed both the PI3K/AKT/NRF2 and p62/NRF2 pathways, consequently downregulating GPX1 and GPX4 expression, resulting in significantly elevated levels of reactive oxygen species (ROS) and lipid oxidation in erythroid cells. Furthermore, the oxidizing agent HO induced ER stress dose-dependently, inhibiting in vitro erythroid differentiation of mouse fetal liver cells. Notably, CD44KO erythroblasts demonstrated heightened sensitivity to HO treatment. Our findings elucidate the role of CD44 in maintaining redox homeostasis and proteostasis during terminal erythropoiesis, providing valuable insights into how ROS-induced ER stress contributes to pathogenic erythropoiesis.
跨膜蛋白CD44的表达在终末红细胞生成过程中逐渐下降，标志着成红细胞的分化阶段。尽管其具有重要意义，但CD44在红细胞生成中的具体作用和功能机制仍知之甚少。在本研究中，我们发现CD44基因敲除（CD44KO）小鼠表现出骨髓红细胞生成异常以及苯肼诱导的溶血性贫血加重。单细胞测序分析显示CD44KO成红细胞中内质网（ER）应激激活。具体而言，PERK/eIF2α/ATF4/CHOP通路上调，同时自噬增强并随后导致细胞凋亡。机制上，CD44缺乏抑制了PI3K/AKT/NRF2和p62/NRF2通路，从而下调了GPX1和GPX4的表达，导致红系细胞中活性氧（ROS）水平和脂质氧化显著升高。此外，氧化剂HO剂量依赖性地诱导ER应激，抑制小鼠胎肝细胞的体外红系分化。值得注意的是，CD44KO成红细胞对HO处理表现出更高的敏感性。我们的研究结果阐明了CD44在终末红细胞生成过程中维持氧化还原稳态和蛋白质稳态的作用，为ROS诱导的ER应激如何导致病理性红细胞生成提供了有价值的见解。
