Regulation of Inflammatory Cytokine Expression in Pulmonary Epithelial Cells by Pre-B-cell Colony-enhancing Factor via a Nonenzymatic and AP-1-dependent Mechanism
Regulation of Inflammatory Cytokine Expression in Pulmonary Epithelial Cells by Pre-B-cell Colony-enhancing Factor via a Nonenzymatic and AP-1-dependent Mechanism
复制标题
前 B 细胞集落增强因子通过非酶和 AP-1 依赖性机制调节肺上皮细胞中炎症细胞因子的表达
DOI：
10.1074/jbc.m109.002519
复制
发表时间：
2009-10-02
影响因子：
4.8
通讯作者：
Ye, Shui Qing
中科院分区：
文献类型：
--
作者：
Liu, Peng;Li, Hailong;Ye, Shui Qing
虽然我们之前的研究发现b细胞前集落增强因子（PBEF）在急性肺损伤中是一个高度上调的基因，可以刺激其他炎症细胞因子的表达，但其潜在的分子机制仍有待充分阐明。越来越多的证据表明，PBEF是一种参与哺乳动物NAD合成挽救途径的烟酰胺磷酸核糖基转移酶。本研究旨在确定PBEF刺激炎症细胞因子表达的作用是否取决于其酶活性。我们制备了两个人PBEF突变体（H247E和H247A）重组蛋白和过表达构建体，在A549细胞中过表达，证实这两个突变体的酶活性几乎或完全被消除。两个突变体在mRNA水平和蛋白质水平上刺激白细胞介素-8 （IL-8）的表达，其效果与野生型PBEF相同。这些影响是由于IL-8基因的转录增加，而不是mRNA的稳定性。报告基因分析和凝胶转移实验表明，AP-1转录因子介导了这些作用。p38 MAPK通路抑制剂SB203580和JNK抑制剂1可以减弱这些作用。两种PBEF突变体同样刺激了另外两种炎症细胞因子的表达：IL-16和CCR3。这些结果表明，PBEF通过其非酶活性刺激IL-8、IL-16和CCR3的表达。这种作用是ap -1依赖性的，部分通过p38 MAPK途径和JNK途径。这一发现揭示了PBEF在急性肺损伤和其他炎症性疾病发病机制中的新作用。
Although our previous studies found Pre-B-cell colony-enhancing factor (PBEF) as a highly up-regulated gene in acute lung injury that could stimulate expressions of other inflammatory cytokines, the underlying molecular mechanisms remain to be fully elucidated. Growing evidence indicates that PBEF is a nicotinamide phosphoribosyltransferase involved in the mammalian salvage pathway of NAD synthesis. This study was designed to determine whether the effect of PBEF to stimulate expressions of inflammatory cytokines depends on its enzymatic activity. We prepared two human PBEF mutant (H247E and H247A) recombinant proteins and overexpressing constructs for their overexpressions in A549 cells and confirmed that enzymatic activities of both mutants were nearly or completely abolished. Two mutants stimulated interleukin-8 (IL-8) expression at both the mRNA level and protein level just as equally effective as the wild-type PBEF did. These effects were due to the increased transcription, not the mRNA stability, of the IL-8 gene. Reporter gene assays and gel shift experiments indicated that AP-1 transcription factor is required to mediate these effects. SB203580, a p38 MAPK pathway inhibitor, and JNK inhibitor 1 can attenuate these effects. Both PBEF mutants similarly stimulated the expression of two other inflammatory cytokines: IL-16 and CCR3. These results indicate that PBEF stimulated expression of IL-8, IL-16, and CCR3 via its non-enzymatic activity. This effect is AP-1-dependent, in part via the p38 MAPK pathway and the JNK pathway. This finding reveals a new insight, which may manifest a novel role of PBEF in the pathogenesis of acute lung injury and other inflammatory disorders.