Mir-29b2对T1/T2 B细胞发育的调控作用及机制研究

microRNA play pivotal roles in the development of lymphocytes. T1/T2 cells undertake the key processing for B cell positive and negative selection.Whether MicroRNAs are also involved in the development of T1/T2 cells is largely unknown. At present study, we established mir-29b2 chimeric mice, FACS analysis showed that the percentage of total B cells and different subsets were increased, the ratio of T1:T2 was seriously inverted.By Brdu annexinV staining, we found that the self-renew of B cells was much quicker than that in normal mice and apoptosis of mir-29b2 over-expressed B cells was decreased.suggested that mir-29b2 play important role in B cell development. we made mir-29b2 transgenic mice to further explore the function and mechanism in T1/T2 cells development, and try to verify the functional target gene such as Atk3,PIK3R,NFAT5 of mir-29b2 in T1/T2 cells. To check whether mir-29b2 also affect the B cell tolerance.these study will give a new deciperment for B cell development, B cell tolerance and lymphoma.

研究表明microRNA在淋巴细胞发育和活化中发挥重要作用。T1/T2 细胞肩负着B细胞的阳性和阴性选择，在B细胞发育中担任极其重要的角色。microRNA是否参与T1/T2发育的调控尚未见报道。我们通过建立mir-29b2嵌合小鼠模型研究发现：过表达mir-29b2后B细胞比例增多，T1/T2 比例严重倒置。通过Brdu和annexinV 染色发现，过表达mir-29b2后B细胞自我更新加快，凋亡减少。预实验结果充分显示mir-29b2在T1/T2 B细胞发育中发挥重要作用。为探讨mir-29b2在T1/T2细胞发育中的作用和机制，我们建立了mir-29b2转基因小鼠动物模型；拟通过细胞和分子生物学方法鉴定mir-29b2 功能性靶基因Atk3、PIK3R、NFAT5等；并初步探讨mir-29b2是否影响B细胞免疫耐受。从而为T1/T2发育和B细胞免疫耐受提供新的理论解释。

研究表明microRNA在淋巴细胞发育和活化中发挥着重要的作用。T1/T2 细胞肩负着B细胞的阳性和阴性选择，在B细胞发育中担任极其重要的角色。microRNA是否参与T1/T2发育的调控尚未见报道。通过分析miR-29b2嵌合小鼠模型和转基因小鼠模型的表型，我们发现miR-29b2影响了CLP向preproB细胞的发育和T1/T2细胞的比例，但对外周B细胞（脾脏B细胞各亚群）的影响并不显著。进一步研究表明miR-29b2并不明显改变MPP和HSC等前体祖细胞的比例，但使CLP比例显著下降。通过增殖和凋亡检测发现miR-29b2并没显著影响CLP的增殖和凋亡。因此我们推测miR-29b2可能通过促进CLP向preproB细胞转化而使其减少，从而表现为preproB 细胞增多。同时miR-29b2使T1、T2细胞增殖增多，但T1凋亡减少，T2凋亡增多。通过细胞和分子生物学方法鉴定miR-29b2的可能靶基因为AKT，PTEN，Tet等而不是CCND2。这些基因是否是其功能性靶基因还有待进一步实验证明。常规观察和病理检查并未发现miR-29b2转基因小鼠有明显异常，初步断定过表达miR-29b2并不引起B细胞导致的自身免疫性疾病。