Lokuta M A, Maher J, Noe K H, Pitha P M, Shin M L, Shin H S
Department of Pathology, University of Maryland, School of Medicine, Baltimore, Maryland 21201, USA.
J Biol Chem. 1996 Jun 7;271(23):13731-8. doi: 10.1074/jbc.271.23.13731.
We have previously defined the lipopolysaccharide (LPS)-responsive element (LRE) in the promoters of murine RANTES (regulated on activation normal T-cell expressed) (MuRantes) and murine IP-10/crg-2, chemokines which have potent chemotactic properties for inflammatory cells including monocytes and T lymphocytes. In the present work, we studied the transcriptional mechanism of MuRantes gene induction by virus and compared it with that of LPS in an effort to understand the host responses to virus and bacterial toxins at the molecular level. MuRantes mRNA expression is induced by Newcastle disease virus (NDV) and LPS in the RAW 264.7 macrophage cell line and peritoneal macrophages of LPS-responsive C3HeB/FeJ mice. In LPS-hyporesponsive C3H/HeJ mice, only NDV induces this chemokine gene, indicating that the pathways of transcriptional activation by NDV and LPS are not identical. Using a transient transfection assay, the minimal virus-responsive element (VRE) was localized between nt -175 and -116. The VRE contains previously defined LRE motif 1 (TCAYRCTT) and motif 3 ((T/A)GRTTTCA(G/C)TTT), which were shown to also be important for initiation of transcription by virus. NDV-stimulated nuclear extracts were tested for trans-activating factors able to bind the VRE. The chromosomal protein HMG-I(C) was shown to bind the 3'-A.T-rich domains of the VRE, and the presence of HMG-I(C) was demonstrated in the VRE-protein complex formed with nuclear extracts from NDV-stimulated, but not unstimulated cells. These findings demonstrate the role of HMG-I(C) in activation of MuRantes promoter by NDV.
我们之前已经在小鼠RANTES（活化正常T细胞表达调控因子）（MuRantes）和小鼠IP-10/crg-2启动子中定义了脂多糖（LPS）反应元件（LRE），这两种趋化因子对包括单核细胞和T淋巴细胞在内的炎症细胞具有强大的趋化特性。在本研究中，我们研究了病毒诱导MuRantes基因的转录机制，并将其与LPS的转录机制进行比较，以在分子水平上了解宿主对病毒和细菌毒素的反应。MuRantes mRNA表达在RAW 264.7巨噬细胞系和LPS反应性C3HeB/FeJ小鼠的腹腔巨噬细胞中可被新城疫病毒（NDV）和LPS诱导。在LPS低反应性的C3H/HeJ小鼠中，只有NDV能诱导该趋化因子基因，这表明NDV和LPS的转录激活途径并不相同。通过瞬时转染试验，最小病毒反应元件（VRE）定位在核苷酸-175至-116之间。VRE包含先前定义的LRE基序1（TCAYRCTT）和基序3（(T/A)GRTTTCA(G/C)TTT），已证明这些基序对病毒转录起始也很重要。对NDV刺激的核提取物进行测试，以寻找能够结合VRE的反式激活因子。已证明染色体蛋白HMG-I(C)能结合VRE的富含A·T的3'结构域，并且在与NDV刺激而非未刺激细胞的核提取物形成的VRE-蛋白复合物中证实了HMG-I(C)的存在。这些发现证明了HMG-I(C)在NDV激活MuRantes启动子中的作用。
