核不均一核糖蛋白HNRPDL促白血病细胞生长的研究

核不均一核糖蛋白（hnRNP）家族成员HNRPDL是DNA/RNA结合蛋白，参与RNA代谢调控。慢性髓细胞白血病（CML）是造血干细胞获得BCR/ABL融合基因而诱发的恶性血液病。我们报道HNRPDL在CML患者CD34+细胞中表达增高，但其在CML干/祖细胞中的功能与作用机制尚未知。预研显示HNRPDL沉默抑制患者CD34+细胞生长；过表达HNRPDL恶性转化小鼠造血BaF3细胞；HNRPDL可以影响mRNA（如PBX1）稳定性而行使功能。将检测HNRPDL沉默对CML患者细胞的长期培养起始细胞（LTC-IC）和免疫缺陷小鼠体内生长能力的影响；研究HNRPDL单独或与BCR/ABL共同促进小鼠造血干/祖细胞生长和转化的作用；鉴定mRNA稳定性受HNRPDL调控而参与其促CML细胞生长的功能靶基因。项目实施将深化对hnRNPs促白血病细胞生长功能的认知，并为改善疾病治疗提供新的理论基础。

Heterogeneous nuclear ribonucleoproteins (hnRNPs) represent a large family of RNA-binding proteins. Heterogeneous nuclear ribonucleoprotein D-like (HNRPDL) is a member of this family, which is able to bind both RNA and DNA regulating multiple steps of mRNA metabolism. Chronic myeloid leukemia (CML) originates from hematopoietic stem cells acquiring BCR/ABL fusion gene. Previous study has shown that HNRPDL is aberrantly expressed in CD34+ cells from CML patients; however what role it plays in these cells has not been elucidated yet. Herein, we showed that HNRPDL silencing inhibited the colony-forming cell (CFC) capacity of CML CD34+ cells; strikingly, overexpression of HNRPDL in murine BaF3 cells induced lethal leukemia in mice, suggesting HNRPDL is a proto-oncogene. Mechanistically, we showed that HNRPDL impaired the stability of pre-B-cell leukemia homeobox 1 (PBX1) mRNA in K562 cells (BCR/ABL+) and PBX1 silencing inhibited the growth of these cells. In this proposal, we will perform long-term culture initiating cell (LTC-IC) assay to assess the effect of HNRPDL silencing on primitive CML cells, and analyze the effect of HNRPDL silencing on the growth of primitive CML cells in NSG mice. On the contrary, we will study the effect of HNRPDL alone and with BCR/ABL on the growth of murine hematopoietic stem/progenitor cells in vitro and in vivo. Lastly, we will generate microarray data comparing HNRPDL silenced CML CD34+ cells with their control cells, and identify the genes that play a role in the HNRPDL silencing mediated growth inhibition and are regulated by HNRPDL through mRNA decay. The execution of the project will deepen the understanding of the role of hnRNPs in human leukemia and possibly provide new clues for the improvement of the disease management.