Brady Gareth, Whiteman Hannah J, Spender Lindsay C, Farrell Paul J
Department of Virology, Faculty of Medicine, Imperial College London, Norfolk Place, London W2 1PG, United Kingdom.
J Virol. 2009 Jul;83(13):6909-16. doi: 10.1128/JVI.00216-09. Epub 2009 Apr 29.
Cross-regulation of RUNX1 expression by RUNX3 plays a critical role in regulating proliferation of human B cells infected with Epstein-Barr virus (EBV). When EBV infection induces RUNX3, the consequent reduction in RUNX1 levels is required for the ensuing cell proliferation because forced expression of RUNX1 in an EBV lymphoblastoid cell line prevented cell proliferation. The TEL-RUNX1 fusion gene from acute B-lymphocytic leukemia retains almost all of the RUNX1 sequence but does not prevent B-cell proliferation in the same assay. B-cell maturation antigen (BCMA) was found to be induced by conditionally expressed RUNX3 in a lymphoma cell line. Chromatin immunoprecipitation assays confirmed that RUNX3 binds to the RUNX1 promoter in a lymphoblastoid cell line and a Burkitt's lymphoma cell line. The TLE binding VWRPY sequence from the C terminus of RUNX3 was found to be required for repression of the RUNX1 P1 promoter in a B-lymphoma cell line. The mechanism of repression in B-cell lines most likely involves recruitment of corepressor TLE3 or TLE4 to the RUNX1 promoter. The results demonstrate the importance of RUNX3-mediated repression of RUNX1 for EBV-driven B-cell proliferation and identify functional differences between human RUNX family proteins.
RUNX3对RUNX1表达的交叉调节在调控感染爱泼斯坦-巴尔病毒(EBV)的人B细胞增殖中起关键作用。当EBV感染诱导RUNX3表达时,随后RUNX1水平的降低是后续细胞增殖所必需的,因为在EBV淋巴母细胞系中强制表达RUNX1会阻止细胞增殖。急性B淋巴细胞白血病中的TEL-RUNX1融合基因保留了几乎所有的RUNX1序列,但在相同检测中并不阻止B细胞增殖。在淋巴瘤细胞系中发现条件性表达的RUNX3可诱导B细胞成熟抗原(BCMA)。染色质免疫沉淀试验证实RUNX3在淋巴母细胞系和伯基特淋巴瘤细胞系中与RUNX1启动子结合。发现RUNX3 C末端的TLE结合VWRPY序列是B淋巴瘤细胞系中抑制RUNX1 P1启动子所必需的。B细胞系中的抑制机制很可能涉及共抑制因子TLE3或TLE4募集到RUNX1启动子。这些结果证明了RUNX3介导的对RUNX1的抑制对EBV驱动的B细胞增殖的重要性,并确定了人类RUNX家族蛋白之间的功能差异。