Ubc13调控造血干细胞炎性反应的细胞和分子机制研究

Chronic exposure to pro-inflammatory signals damages hematopoietic stem cells (HSCs) and results in bone marrow failure, yet anti-inflammatory mechanisms that protect HSCs are understudied. Our previous study revealed STAT3 restrains pro-inflammatory responses and preserve HSC function by inhibiting expression of Ubc13, an E2 ubiquitin-conjugating enzyme involved in inflammatory responses. Therefore, it collectively suggested hyperactivation of Ubc13 might directly contribute to endogenous proinflammatory damages in hematopoietic stem and progenitor cells (HSPCs). We identified multiple proteins, which involved in modulating mitochondria function and were proved to be critical for HSC stemness or differentiation, were deregulated in absence of Ubc13 through RNAseq. Therefore, we propose a crucial role for Ubc13 in HSCs preservation through regulating critical mitochondrial proteins. We will explore the cell intrinsic function of Ubc13 in HSCs and their mitochondria under both homeostasis and inflammatory settings, and reveal transcriptome and proteomics changes in the presence or absence of Ubc13 in HSC. We expect to reveal novel cellular and molecular mechanism of how Ubc13 regulates HSC functions, and provide fundamental new insight to identify potential therapeutic targets to protect HSC from inflammatory insults.

慢性持续炎症反应可导致造血干细胞（hematopoietic stem cell，HSC）功能衰竭, 然而保护HSC免受炎性伤害的分子机制依然所知甚少。申请人近期阐明了STAT3通过抑制E2泛素化结合酶Ubc13保护HSC免受炎性损伤的分子机制，成果提示Ubc13高表达是诱导HSC内源性炎性损伤的关键环节。申请人通过RNA测序发现Ubc13敲除后，多个调控HSC线粒体关键功能的蛋白表达失调。基于上述工作基础，申请人拟通过Ubc13敲除和过表达两种小鼠模型，分别探究生理稳态和炎症刺激下，Ubc13对HSC功能，转录组和蛋白组的调控，以及对线粒体功能和关键蛋白表达水平的影响。验证Ubc13通过调控线粒体关键蛋白和线粒体功能，影响HSC干性，分化和生存的中心科学假说。通过实施上述计划，预期获得Ubc13调控HSC和线粒体功能细胞和分子机制，为拮抗HSC炎症反应提供治疗新策略和潜在药物靶点。

慢性持续炎症反应可以造成造血干细胞（hematopoietic stem cell, HSC）损伤，数量减少、失去干性、干细胞功能衰竭和分化失衡等，甚至诱发多种恶性血液系统疾病，如骨髓增生异常综合症（myelodysplastic syndrome，MDS）和急性髓系细胞白血病（AML）。 然而，保护造血干细胞（hematopoietic stem cell，HSC）免受炎性伤害的分子机制依然所知甚少。本研究针对上述问题，建立单细胞测序平台，探究造血干细胞炎性老化的过程中不同异质性亚群转录组学的变化，以及Ubc13对其的影响。繁育获得造血干细胞Ubc13特异性过表达和敲除小鼠模型，并进行体内外功能实验，包括流式细胞分析和骨髓移植等，探究过表达Ubc13对造血干细胞的功能影响。探究不同炎症介质刺激下，Ubc13对调控线粒体关键基因和功能的影响。建立微量细胞蛋白质组学平台，探究造血干细胞炎性老化的过程蛋白质表达修饰的动态变化，以及H4K77ac对HSC谱系分化的影响。上述成果，为深入理解HSC炎性老化和谱系偏移提供了理论基础和实验依据，并为进一步逆转免疫老化提供了新的靶点。

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