干细胞分化为巨核细胞进而产生的血小板在止血、炎症反应、血栓形成等生理和病理过程中发挥重要作用。但是，目前对调控巨核分化以及血小板发生的机制了解不多。我们近期的研究表明MEIS1敲除显著抑制人多能干细胞巨核细胞分化，完全阻断了巨核细胞多倍体化和血小板生成，但分子机制不详。本研究中，我们计划首先通过化学小分子文库、转录因子文库功能筛选结合转录组以及CHIP-Seq分析，利用干细胞巨核分化和产生血小板等模型鉴定介导MEIS1作用的新的靶基因，然后通过CRISPR/CAS9等方法研究这些新基因在巨核分化和血小板发生过程中的功能以及与MEIS1的相互调控作用；最后，我们将利用骨髓增殖异常综合征(MDS)作为血液病模型，探讨MEIS1及其下游靶基因对疾病发生发展的影响。本研究的开展预期将鉴定MEIS1新的靶基因并揭示其在病理和生理条件下对巨核分化和血小板发生中的影响和作用的分子机理。

Platelets, the small anucleate cells generated from stem cell derived megakaryocytes, play important roles in many pathophysiological processes such as hemostasis, inflammation, and thrombosis. However, there is not much understanding of the regulatory mechanism of megakaryopoiesis and thrombopoiesis. Our recent studies have shown that MEIS1 knockout significantly inhibits the megakaryocytic differentiation of human pluripotent stem cells and completely blocks the polyploidization of megakaryocytes and platelet generation, but the mechanism remains elusive. In this study we will explore the new target genes of MEIS1 during megakaryopoiesis and thrombopoiesis through the functional screening of small molecule and transcription factor libraries, combining with the analysis of RNA-Seq and ChIP-Seq. Then the functions of these new target genes and the interactions with MEIS1 in the process of megakaryocyte and platelet generation will be further studied by using CRISPR/CAS9 technology. Finally, we will explore the effects of MEIS1 and its downstream targets on the occurrence and development of platelet disorders based on the study model of meylodysplastic syndrom (MDS). This study is expected to identify the new target genes of MEIS1 and reveal the functions and molecular mechanisms of these genes regulating megakaryocytic differentiation and thrombopoiesis in pathological and physiological conditions.