Mechanism and Function of Endoplasmic Reticulum Protein Quality Control Machinery In The Maintenance of Hematopoietic Stem Cells

内质网蛋白质控机制在造血干细胞维持中的作用机制及作用

• 批准号: 10386803
• 负责人: Xi Chen
• 金额: $ 50.24万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10386803
• 关键词: Address; Aging; Apoptosis; Blood; Bone Marrow; Bone Marrow Purging; Bone Marrow Transplantation; CXCR4 Receptors; CXCR4 gene; Cell Cycle; Cell Death; Cell Maintenance; Cells; Complex; Data; Development; Endoplasmic Reticulum; Endoplasmic Reticulum Degradation Pathway; Engraftment; Fluorouracil; Frequencies; Genome; Hematological Disease; Hematopoiesis; Hematopoietic; Hematopoietic Stem Cell Transplantation; Hematopoietic stem cells; Homeostasis; Impairment; Infection; Injury; Integral Membrane Protein; Knock-out; Knockout Mice; Knowledge; Leukemic Cell; Life; Lymphoma cell; Maintenance; Mediating; Molecular; Monitor; Pathway interactions; Phenotype; Physiological; Play; Post-Translational Regulation; Process; Proteins; Proteome; Quality Control; Regenerative Medicine; Regulation; Research; Role; Sickle Cell Anemia; Stress; Surface; System; Therapeutic Intervention; Tissues; cell injury; clinical application; conditional knockout; defined contribution; endoplasmic reticulum stress; genome integrity; hematopoietic stem cell fate; hematopoietic stem cell niche; hematopoietic stem cell quiescence; in vivo; insight; misfolded protein; mouse model; novel; physiologic stressor; prevent; receptor; reconstitution; response; self-renewal; sensor; stem cell biology; stem cell division; stem cell engraftment; stem cell function; stem cells; transcriptome sequencing

ABSTRACT Hematopoietic stem cells (HSCs) maintain tissue homeostasis and replenish blood system upon stresses. HSCs have evolved unique mechanisms to maintain genome and proteome integrity throughout life. While the genome integrity safeguard mechanisms have been extensively studied, little is known about how proteome integrity is maintained in HSCs and how dormant HSCs are protected from protein damage during development and physiological stresses. This proposal will address this knowledge gap. We recently found that the Sel1L ER-associated degradation (ERAD) pathway plays an essential role in the maintenance of HSCs. ERAD is the principal protein quality control mechanism responsible for targeting misfolded proteins in the ER for cytosolic proteasomal degradation. The Sel1L-Hrd1 complex is the most conserved branch of ERAD. Using a conditional knockout mouse model, we found that Sel1L deletion in hematopoietic cells significantly reduced steady-state HSC frequency and led to complete loss of HSC reconstitution capacity in stress conditions including bone marrow transplantation and 5-fluorouracil (5-FU) mediated myeloablation. Interestingly, Sel1L deletion did not induce apoptosis or impair HSC engraftment. In contrast, we observed increased HSC cycling and reduced numbers of quiescent HSCs in Sel1L knockout mice. These data demonstrate the critical function of Sel1L ERAD in HSC maintenance and suggest a novel role for ER protein quality control machinery in regulating stem cell quiescence and self-renewal. ERAD monitors and regulates the maturation of transmembrane proteins. We found markedly decreased surface expression of CXCR4 and MPL, two master regulators of HSC quiescence and niche interaction, in Sel1L-knockout HSCs. Tracking HSC and niche cells at the single cell level in vivo showed aberrant localization of Sel1L-deficient HSCs in the bone marrow niche. We hypothesize that Sel1L ERAD governs HSC quiescence and self-renewal by regulating HSC transmembrane receptor maturation and HSC-niche interaction. We will establish the physiological significance of Sel1L ERAD in the maintenance of HSCs (Aim 1), determine the significance and mechanism of the ERAD- Unfolded Protein Response (UPR) crosstalk in HSCs (Aim 2), and elucidate the mechanism and significance of Sel1L ERAD in HSC-niche interactions (Aim 3). This study will provide significant insight into the post- translational regulation of HSC quiescence, self-renewal, and niche interaction by ER protein quality control mechanisms, and further identify novel determinants of HSC fates.

抽象的 造血干细胞（HSC）在压力下维持组织稳态并补充血液系统。 HSC 已进化出独特的机制来在整个生命周期中维持基因组和蛋白质组的完整性。虽然 基因组完整性保障机制已被广泛研究，但人们对蛋白质组如何实现知之甚少 维持 HSC 的完整性以及如何保护休眠的 HSC 免受蛋白质损伤 发育和生理压力。该提案将解决这一知识差距。我们最近发现 Sel1L ER 相关降解 (ERAD) 途径在维持 HSC。 ERAD 是主要的蛋白质质量控​​制机制，负责针对错误折叠的蛋白质 ER 用于胞质蛋白酶体降解。 Sel1L-Hrd1 复合体是最保守的分支 ERAD。使用条件敲除小鼠模型，我们发现造血细胞中 Sel1L 缺失 显着降低稳态 HSC 频率并导致 HSC 重建能力完全丧失 应激条件包括骨髓移植和 5-氟尿嘧啶 (5-FU) 介导的清髓术。 有趣的是，Sel1L 缺失不会诱导细胞凋亡或损害 HSC 植入。相比之下，我们观察到 Sel1L 敲除小鼠中 HSC 循环增加并减少静态 HSC 数量。这些数据 证明 Sel1L ERAD 在 HSC 维持中的关键功能，并提出 ER 蛋白的新作用 调节干细胞静止和自我更新的质量控制机制。 ERAD 监控和调节 跨膜蛋白的成熟。我们发现CXCR4和CXCR4的表面表达显着降低 MPL 是 Sel1L 敲除 HSC 中 HSC 静止和生态位相互作用的两个主要调节因子。追踪HSC 体内单细胞水平的微环境细胞显示 Sel1L 缺陷型 HSC 在骨中的异常定位 骨髓利基。我们假设 Sel1L ERAD 通过调节 HSC 来控制 HSC 静止和自我更新 跨膜受体成熟和 HSC-niche 相互作用。我们将确定生理意义 Sel1L ERAD 在 HSC 维持中的作用（目标 1），确定 ERAD- 的意义和机制 HSC 中的未折叠蛋白反应 (UPR) 串扰（目标 2），并阐明其机制和意义 HSC-生态位相互作用中的 Sel1L ERAD（目标 3）。这项研究将为后世提供重要的见解 通过 ER 蛋白质量控制对 HSC 静止、自我更新和生态位相互作用进行翻译调控 机制，并进一步确定 HSC 命运的新决定因素。