骨髓微环境中Slug对造血干细胞生物学行为的调控作用及机制的研究

The applicant of this project has a solid research foundation in the regulation of hematopoietic stem cells (HSCs) (two Blood papers). Increasing evidences suggest that the stemness (self-renewal and differentiation) of HSCs is precisely regulated by many types of stromal cells found in bone marrow microenvironment (niche) and their secretary factors. Slug belongs to the highly conserved Slug/Snail family of zinc-finger transcription factors found in diverse species ranging from C. elegans to humans. Our previous study has already demonstrated that Slug serves intrinsic role in the regulation of HSC fates (Blood, 2010, 115(9):1709-1717). Our preliminary experiments showed that 1) there is bone defect in Slug-/- mice, 2) Slug-/- bone marrow microenvironment has contributed to HSC expansion, 3) Slug-/- bone marrow microenvironment displays the increased expression of stromal N-cadherin, VCAM1, Jagged1 and angiopoietin 1 which positively regulate the fates of HSCs, and 4) the number decrease of adipocytes within bone marrow microenvironment has contributed to HSC hematopoietic reconstitution, suggesting that Slug might be also extrinsically required for HSC fate regulation. Against this background, the present project plans to carry out the following studies: 1) the expression and distribution of Slug in niche cells and the relationship between niche cells and HSCs are analyzed; 2) Slug conditional knockout mice will be used to fully dissect the functions of Slug in bone marrow niche in regulating various niche cells and HSC fates; 3) the dynamic changes of bone marrow niche cells and their relationship with HSCs will be observed by reporter gene cell tracking; 4) to elucidate the related molecular mechanisms and discover target genes. The expected findings will shed light on new mechanisms of HSC regulation, and provide new ideas for in vitro amplification of HSCs and the clinical application of hematological disease treatment.

造血干细胞(HSCs)自我更新和分化等行为调控机制的研究是干细胞领域的热点。申请人在HSCs行为调控研究方面具备坚实基础(Blood两篇)。骨髓微环境中各种基质细胞及其分泌的成分精细调控HSCs行为,进一步发现微环境中关键调控因子至关重要。前期研究发现，Slug-/-小鼠骨骼发育异常，其骨髓微环境利于HSCs扩增，骨髓基质细胞中HSCs正调控因子(Tie2和VCAM等)表达上调,其微环境中脂肪细胞减少而加速造血重建，提示骨髓微环境中Slug可能参与HSCs行为调控。据此，本项目拟开展如下工作：分析Slug在niche细胞中的表达和分布及与HSCs关系；利用Slug条件基因敲除小鼠，阐明骨髓微环境中Slug对niche细胞和HSCs的调控作用；利用报告基因示踪法观察niche细胞与HSCs关系；阐明相关分子机制。研究将揭示HSCs行为调控新机制，并为HSCs体外扩增和血液病治疗提供新思路。

造血干细胞(HSCs)自我更新和分化等行为调控机制的研究是干细胞领域的热点。骨髓微环境中各种基质细胞及其分泌的成分精细调控HSCs行为,进一步发现微环境中关键调控因子至关重要。研究发现，Slug-/-小鼠骨骼发育异常，其骨髓微环境利于HSCs扩增以及促进造血重建。项目进一步利用各种Slug条件基因敲除小鼠，阐明Slug在不同niche细胞中敲除后对HSCs命运的影响，最后发现Slug通过影响骨髓微环境中的脂肪前体细胞从而调控造血干祖细胞的生物学行为，并初步阐明Slug是通过何种方式及分子机制影响特定niche细胞的功能，进而影响HSCs命运。研究将揭示HSCs行为调控新机制，并为HSCs体外扩增和血液病治疗提供新思路。