p18在造血干细胞向B细胞分化中的作用及机制研究

As an important member of the cyclins-dependent kinase inhibitors, p18IKN4C(CDKN2C, p18) plays a critical role in regulating the self-renewal and differentiation of hematopoietic stem cell(HSC) and also participates in the development and maturation of lymphoid cells(including B and T cells). Deletion of p18 induces the development of vicious blood diseases (especially the plasmacytoma and myeloma). But the role of p18 in the differentiation from HSC toward B cells and mechanism is poorly understood. Our previous data showed that the B cell percentage was decreased in the bone marrow and spleen of p18 knock out (KO) mice, while the cell cycle, apoptosis and proliferation of B cells had no change. Interestingly, the differentiation of HSC toward B cells was decreased in the bone marrow transplantation with the unknown mechanism..In our proposed study, we will use a series of advanced techniques including flow cytometry, bone marrow transplantation and single cell PCR to investigate the characteristics and functional changes of B cells in the p18KO mice, reveal the role of p18 in the differentiation of HSC toward B cells as well as related mechanism and establish the disease model to find out the relationship between p18 deletion and the clinical blood diseases. We hope to identify the critical influence of p18 in the differentiation of HSC towards B cells and the effect of p18 in the initiation and development of hematologic diseases, thus to provide the theory evidences and therapy strategies for the blood disease patients with the absence of p18.

p18INK4C（CDKN2C，p18）是调控造血干细胞（HSC）自我更新和分化的重要分子，也对淋巴细胞（B和T细胞）的发育和成熟发挥关键作用。临床上p18缺失会导致多种恶性血液疾病（如浆细胞淋巴瘤/骨髓瘤）的发生。但p18在HSC向B细胞分化发育过程中的作用及分子机制鲜有报道。我们前期研究发现p18缺失小鼠骨髓和脾脏B细胞比例显著下降，但B细胞本身生物学特性并无显著改变。骨髓移植结果提示p18缺失的HSC向B细胞的分化出现障碍，但分子机制不清。本研究将主要运用流式细胞术、骨髓移植、单细胞PCR等技术和方法深入研究p18缺失小鼠B细胞分化和发育的异常及其生物学特性和功能改变，揭示p18在HSC向B细胞分化过程中的作用并探讨相关分子机制，同时在p18缺失基础上构建恶性血液疾病动物模型，探索p18与疾病发生发展的相关性，为临床上存在p18缺失的血液疾病患者的治疗提供潜在的理论依据和治疗策略。

p18INK4C （p18）是调控造血干细胞（HSC）自我更新和分化的重要分子。也对淋巴细胞的发育和成熟发挥关键作用。临床上p18缺失会导致多种恶性血液疾病（如浆细胞淋巴瘤／骨髓瘤）的发生，尤其是在多发性骨髓瘤病例中，同时携带p18基因缺失的病人预后不良。但是p18在HSC向B细胞分化发育过程中的作用及分子机制鲜有报道。本研究利用p18基因系统性缺失的小鼠模型展开研究。研究发现在p18基因缺失小鼠骨髓和脾脏中B细胞频率显著下降，主要表现在骨髓Pre-B和Imm-B阶段和脾脏的T2-B和FO-B阶段；p18基因敲除的B细胞本身的增殖、凋亡、细胞周期等生物学特性与对照组并无显著改变；体内连续移植实验结果发现p18缺失的造血干祖细胞（LSK细胞）向B细胞的分化能力下降，过表达p18可部分逆转B系发育阻滞的表型；在分子机制上可能与p18敲除的造血干祖细胞高表达去甲基化相关的基因相关，深入的信号通路正在进一步研究中。本研究揭示了p18缺失导致B细胞减少源于造血干祖细胞向B细胞的分化发育阻滞所致，对临床上携带p18基因缺失的多发性骨髓瘤病人是否能够实施自体HSC移植提供了基础研究的证据。