Functional Role of Tetraspanin CD82 in Hematopoietic Stem Cell Interactions

项目总结 造血系统重要的细胞需求是由罕见的组织特异性的， 主要处于静止状态的造血干细胞和祖细胞(HSPC)。vt.在.的基础上 造血应激，如大量出血、压倒性感染、辐射暴露和 在骨髓抑制治疗中，HSPC被迅速招募到细胞周期中，但最终必须回到 宁静。瞬时调节HSPC返回静止的能力有可能延长 激活HSPC并显著改善来自造血应激的总体患者预后 移植疗法。然而，为了利用HSPC激活的短暂延长来提高 对于压力的再生反应，我们必须首先了解复杂网络 骨髓内的细胞内源性和外源性信号偶联来调节HSPC的静止。这个 我们目前的建议的目的是评估Tetraspanin膜-支架蛋白CD82作为一种 在骨髓中调节HSPC静止信号的易处理靶点。Tetraspanins是一个家族 膜-支架蛋白具有独特的调节细胞-细胞/细胞-基质相互作用和调节 细胞内信号转导，从而将细胞-微环境相互作用与下游信号转导结果联系起来。 我们的新的初步数据表明，CD82支架在细胞 与转化生长因子(转化生长因子)信号转导有关。因此，在这方面 提案中，我们将检验CD82膜支架通过以下方式促进HSPC静止的假设 在骨髓壁龛内组织和增强转化生长因子受体复合体的信号活性。在……里面 具体目标1，我们将确定CD82调控转化生长因子β信号的分子机制 HSPC的反应。对于特定的目标2，我们将确定CD82促进空间发展的机制 造血应激时骨髓内局部转化生长因子信号的激活。以特定的目标 3，我们将评估CD82作为改善造血再生反应的治疗靶点。 血液损伤。为了实现这些目标，我们将应用一种创新的组合方法，包括 突变分析、生物化学和先进的成像技术，这将使我们能够获得多个 CD82调控转化生长因子信号转导机制的研究进展 造血应激。此外，成功完成拟议的目标将具有重大意义，因为我们 希望整合跨多个规模的机械性见解，以确定CD82的多方面贡献 在造血应激和静止的背景下对转化生长因子信号的调节，这将建立一个 为开发局部靶向复杂转化生长因子信号的改进疗法奠定基础 在骨髓中层叠。

PROJECT SUMMARY The significant cellular demand of the hematopoietic system is maintained by a rare pool of tissue-specific, hematopoietic stem and progenitor cells (HSPCs) that are primarily found in a quiescent state. Upon hematopoietic stresses, such as significant bleeding, overwhelming infection, radiation exposure and myelosuppressive therapy, HSPCs are rapidly recruited into cell cycle, but ultimately must return to quiescence. The ability to transiently modulate HSPC return to quiescence has the potential to extend the activation of HSPCs and significantly improve overall patient outcomes from hematopoietic stresses and for transplantation therapies. However, in order to leverage a transient extension of HSPC activation to improve the regenerative response to stress, we must first understand the mechanisms by which the complex network of cell-intrinsic and -extrinsic signaling within the bone marrow are coupled to regulate HSPC quiescence. The objective of our current proposal is to evaluate the tetraspanin membrane-scaffold protein, CD82, as a tractable target to modulate HSPC quiescence signaling within the bone marrow. Tetraspanins are a family of membrane-scaffold proteins with the unique ability to regulate cell-cell/cell-matrix interactions and modulate intracellular signaling, thus linking cell-microenvironment interactions to downstream signaling consequences. Our new preliminary data indicate that the CD82 scaffold promotes a quiescent HSPC phenotype when cells are niche engaged and implicate a role for Transforming Growth Factor  (TGF) signaling. Thus, in this proposal, we will test the hypothesis that the CD82 membrane scaffold promotes HSPC quiescence by organizing and enhancing the signaling activity of a TGF receptor complex within the bone marrow niche. In Specific Aim 1, we will determine the molecular mechanisms by which CD82 modulates the TGFβ signaling response of HSPCs. For Specific Aim 2, we will identify the mechanism by which CD82 promotes the spatial activation of TGF signaling locally within the bone marrow niche during hematopoietic stress. In Specific Aim 3, we will evaluate CD82 as a therapeutic target to improve the hematopoietic regeneration response to hematologic injury. In pursuit of these aims, we will apply an innovative combinatorial approach that includes mutational analysis, biochemistry and sophisticated imaging techniques, which will enable us to obtain a multi- scale understanding of the mechanisms by which CD82 regulates TGF signal transduction in the context of hematopoietic stress. Moreover, the successful completion of the proposed aims will be significant because we expect to integrate mechanistic insights across multiple scales to identify the multifaceted contribution of CD82 to the regulation of TGF signaling in the context of hematopoietic stress and quiescence, which will build a foundation for the development of improved therapeutics that locally target the complex TGF signaling cascade within the bone marrow.