超保守RNA uc.102-106基因簇在B细胞淋巴瘤中的表达调控和作用研究

Burkitt’s lymphoma is a highly invasive B-cell malignancy. Ultraconserved RNA is a class of specific long non-coding RNAs whose sequences are completely conserved among human, rat and mouse. uc.102-106 are five UCRs all located in different introns of the same coding gene ola1 (Obg-like ATPase 1). To investigate the molecular mechanism of lymphomagenesis we established a non-transgenic murine system based on the molecular hallmarks of human Burkitt’s lymphoma: over-expression of c-myc oncogene and inactivation of p53 tumor suppressor. To address whether and how p53 regulates its downstream non-coding RNAs, we generated murine lymphomas engineered with P53-estrogen receptor fusion protein (P53ER). In these lymphomas P53 function can be rapidly toggled between "off" and "on" with 4OH-Tamoxifen. Using this system we have found that the expression level of uc.106 located in the fourth intron of ola1 is increased over three thousand times 15 min after p53 activation. Ｗe have also found that uc.106 strongly inhibits the growth of lymphoma cells both in vitro and in vivo, while other UCRs (uc-102, uc-103, uc-104 and uc.105) and the mRNA from their host gene ola1 are increased only slightly after p53 activation. We thus hypothesize that p53 inhibits lymphomagenesis，at least partially through direct transcriptional regulation of UCRs. In this proposal, we plan to examine 1) how p53 regulates the expression of uc.102-106; 2) the expression profile of uc.102-106 in lymphomas and other tumors; 3) the role of uc.102-106 in lymphomagenesis; and 4) whether uc.102-106 act as anti-sense RNA to control the tumorigenesis. This study will not only shed light on the new biology of tumor suppressor p53, but also provide the potential novel diagnostic biomarkers and therapeutic targets for Burkitt’s lymphomas and other related tumors.

Burkitt’s淋巴瘤（BL）是一种具高度侵袭力的B细胞性恶性疾病。超保守RNA（UCR）是一类大于200核苷酸，其序列在人、大鼠和小鼠中完全保守的长链非编码RNA。uc.102-106是五个位于同一编码基因ola1中的UCR。我们利用自己建立的p53可控表达的BL动物模型发现，p53激活15分钟后uc.106表达急增数千倍，且uc.106具极强的抑制体内淋巴瘤生长的作用，而uc.102-105四个UCR在p53激活后增高只有几倍。由此我们推测，p53可以通过直接调控特定UCR的转录发挥其抑制肿瘤生长的作用。为此本课题计划研究uc.102-106 1）如何受p53调控；2）在肿瘤中的表达谱；3）在淋巴瘤中作用；4）是否作为反义RNA控制淋巴瘤生长。本项目不仅让我们更深入了解p53新的生物学行为，而且将为受p53调控的UCRs作为新的肿瘤诊断标记，尤其是治疗靶点提供理论依据。

Burkitt’s淋巴瘤（BL）是一种具高度侵袭力的B细胞性恶性疾病。超保守RNA（UCR）是一类大于200核苷酸，其序列在人、大鼠和小鼠中完全保守的长链非编码RNA。uc.102-106是五个位于同一编码基因ola1内含子中的UCR。本项目主要研究uc.102-106基因簇在B细胞淋巴瘤中的表达调控和作用。..我们利用自己建立的p53可控表达的BL动物模型发现，p53 激活15分钟后uc.106表达急增数千倍，而uc.102-105四个UCR在p53激活后增高只有几倍。进一步研究发现，p53可结合在uc.106上游启动子区域直接调控uc.106的转录。其次我们发现，过表达uc.106能反向稳定p53表达，形成一个正反馈调控回路：p53的激活可以促进uc.106的转录，而uc.106的表达反馈促进p53蛋白的稳定。..我们还研究发现uc.106能显著抑制B细胞淋巴瘤细胞在体内体外的生长。另外，我们新构建了uc.106基因的敲除模型，发现uc.106敲除后，年轻小鼠表型未出现明显改变，但8月龄之后的敲除小鼠脾脏B细胞增多，18个月以上的部分敲除小鼠自发地发展出肠系膜B细胞淋巴瘤，而正常的小鼠并没有发生肠系膜淋巴瘤，这表明淋巴瘤的发生是由于uc.106的缺失导致的，从而证明uc.106是一个可以抑制淋巴瘤发生的抑癌基因。..uc.106的缺失导致淋巴瘤发生的机制除了与p53相关以外，可能也和uc.106的宿主基因ola1的蛋白水平增高相关。ola1可以结合肿瘤抑制蛋白BRCA1和BARD1，调节细胞分裂时S期的中心体复制，促进细胞分裂。因此，uc.106的过表达可能通过减少ola1/BRCA1/BARD1蛋白复合体形成或降低蛋白复合体的稳定性，形成一个P53-uc.106-ola1轴来维持中心粒数目的稳态，使淋巴细胞不能过度分裂增殖，从而抑制淋巴瘤的发生发展。这些实验结果正在整理成文。..本项目利用p53可控表达的淋巴瘤研究UCR的表达调控机制以及利用我们新构建的UCR敲除小鼠研究UCR在淋巴瘤发生发展过程中的作用，目前未见任何研究报道，因此本项目的研究结果不仅让我们更深入了解p53新的生物学行为，而且为受p53调控的UCRs作为新的肿瘤诊断标记，尤其是治疗靶点提供理论依据。