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: 10594513
• 负责人: Xi Chen
• 金额: $ 50.04万
• 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 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10594513
• 关键词: Aging; Apoptosis; Blood; Bone Marrow; Bone Marrow Purging; Bone Marrow Transplantation; CXCR4 Receptors; CXCR4 gene; Cell Cycle; Cell Death Induction; Cell Maintenance; Cells; Complex; Cytoprotection; Data; Development; Endoplasmic Reticulum; Endoplasmic Reticulum Degradation Pathway; Engraftment; Fluorouracil; Frequencies; Genome; Hematological Disease; Hematopoiesis; Hematopoietic; Hematopoietic Stem Cell Transplantation; Hematopoietic stem cells; Hemorrhage; Homeostasis; Impairment; Infection; Injury; Integral Membrane Protein; Knock-out; Knockout Mice; Knowledge; Leukemic Cell; Life; LoxP-flanked allele; Lymphoma cell; Maintenance; Mediating; Membrane; 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）在压力下保持组织稳态和复制血液系统。 HSC已发展出独特的机制，以维持一生的基因组和蛋白质组完整性。而 基因组完整性保障机制已经广泛研究，对蛋白质组的了解知之甚少 在HSC中保持完整性以及如何保护休眠的HSC免受蛋白质损害 发展和身体压力。该建议将解决这一知识差距。我们最近发现 SEL1L ER相关降解（ERAD）途径在维持中起着至关重要的作用 HSC。 ERAD是负责靶向错误折叠蛋白的主要蛋白质质量控​​制机制 ER用于胞质蛋白酶体降解。 SEL1L-HRD1复合物是最保守的分支 埃拉德。使用条件敲除小鼠模型，我们发现造血细胞中的SEL1L缺失 显着降低了稳态HSC频率，并导致HSC重组能力的完全损失 压力条件在内，包括骨髓移植和5-纤维拉西尔（5-FU）介导的骨髓固定。 有趣的是，SEL1L缺失不会诱导凋亡或损害HSC植入。相反，我们观察到 HSC循环增加并减少了SEL1L基因敲除小鼠的静态HSC数量。这些数据 演示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。伊拉德监视和调节 跨膜蛋白的成熟。我们发现CXCR4的表面表达明显降低 MPL，HSC静止的两个主调节器和SEL1L敲除HSC中的两个主调节器。跟踪HSC 在体内单细胞水平的小众细胞显示了骨骼中SEL1L缺陷HSC的异常定位 骨髓利基。我们假设SEL1L ERAD通过调节HSC来控制HSC的静止和自我更新 跨膜受体成熟和HSC-niche相互作用。我们将建立身体意义 在维持HSC中的SEL1L ERAD（AIM 1）中，确定了ERAD的显着性和机制 HSC中展开的蛋白质反应（UPR）串扰（AIM 2），并阐明 HSC-niche相互作用中的SEL1L ERAD（AIM 3）。这项研究将为后期提供重大见解。 通过ER蛋白质质量控​​制的HSC静止，自我更新和利基相互作用的翻译调节 机制，并进一步识别HSC命运的新颖决定者。