STAT1信号转导促进巨核细胞发育分化和血小板形成的分子机制研究

Megakaryocytes are platelet-producing cells. Excessive proliferation, development, and differentiation of megakaryocytes lead to inflammatory or essential thrombocythemia. STAT1, one major inflammatiory factor, has been shown to promote development and differentiation of megakaryocytes and its signaling is significantly activated in blood cells from essential thrombocythemia patients with JAK2 mutation. Thus we hypothesize that STAT1 signaling is the major player mediating thrombocythemia under pathological conditions. We propose to identify STAT1 target genes in megakaryocytes and study how these genes are regulated by STAT1, what functions they play in megakaryocyte development and differentiation, and the molecular mechansims by which they exert their functions. First, we will probe how STAT1 affects the pathogenesis of essential thrombocythemia using bone marrow transplation. Second, we will identify STAT1 target genes by using G1ME and K562, two megakaryocyte differentiation cell models. And verify their functions of several interesting genes in megakaryopoiesis/thrombopoeisis in vitro and in vivo. Finally, we will dissect the molecular mechanisms by which STAT1 promotes megakaryocyte development and differentiation through regulating TMCC2, RUNX1, and NFE2 genes. And build the molecular regulation network including signal transduction, transcriptional regulation, protein-protein interaction. Once the proposal is carried out, we will be able to fully interpret the pathegenetic mechanism of inflammatory and essential thrombocythemia and provide scientific evidence for clinic interference.

巨核细胞是产生血小板的前体细胞，其过度发育分化导致炎症性和原发性血小板增多症。炎症反应因子STAT1促进巨核细胞发育分化，其信号转导在JAK2突变阳性的原发性血小板增多症中显著活化，可能是导致血小板增多症的重要因素。本课题提出研究STAT1调控巨核细胞发育分化的分子机制，鉴定STAT1靶基因并探讨其在巨核细胞发育分化中的功能和作用机理。首先，利用STAT1缺失小鼠进行骨髓移植，探讨其在原发性血小板增多症发生中的功能。其次，利用巨核细胞体外分化的模型鉴定STAT1靶基因，并验证部分靶基因在体内/体外巨核细胞发育分化和血小板形成中的功能。最后，我们将剖析STAT1通过调控TMCC2、RUNX1、NFE2等基因促进巨核细胞发育分化的分子机制，构建包括信号转导、转录调控、蛋白相互作用等方面的分子调控网络。该课题研究的实施，将全面阐释炎症性和原发性血小板增多症的发病机制，为临床干预提供科学的依据。

本项目系统研究了STAT1在骨髓增殖性肿瘤和原发性骨髓纤维化发生中的功能及其作用的机制，鉴定了多个STAT1作用的靶基因，并深入探讨了这些靶基因在原发性骨髓纤维化及白血病发生中的功能和作用机理。研究发现，STAT1缺失能显著加重由MPL W515L诱发的骨髓增殖性肿瘤的疾病负担。MPL W515L转导的STAT1缺失的骨髓细胞在受体小鼠体内的血细胞增殖更为严重，脾脏肿大、骨髓纤维化加重，并导致129S小鼠死亡，而对照野生型细胞并不能导致小鼠死亡。这些结果表明STAT1是骨髓增殖性肿瘤和原发性骨髓纤维化发生的限制因子。进一步研究显示，STAT1能结合到RUNX1启动子区域，并正向调控RUNX1的表达，提示STAT1可能通过调控RUNX1的表达来影响疾病的发生和进展。研究还鉴定了包括ANP32A、PITHD1、C7ORF41（INKIT）在内的多个靶基因，并阐释了这些基因在巨核细胞发育分化、急性巨核细胞白血病、急性髓系白血病和天然免疫抗病毒反应中的功能和作用机理。本研究大大促进了对相关疾病发生机制的理解，为这些疾病的预防和治疗提供科学的依据和潜在的分子靶标。