Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Infect Immun. 2010 Mar;78(3):1058-65. doi: 10.1128/IAI.01141-09. Epub 2010 Jan 11.
Dectin-1 is an important macrophage phagocytic receptor recognizing fungal beta-glucans. In this study, the mRNA levels of the Dectin-1 gene were found to be decreased by 61% in alveolar macrophages (AMs) from Pneumocystis-infected mice. The expression of Dectin-1 protein on the surface of these cells was also significantly decreased. By fluorescence in situ hybridization, mRNA expression levels of the transcription factor PU.1 were also found to be significantly reduced in AMs from Pneumocystis-infected mice. Electrophoretic mobility shift assay showed that PU.1 protein bound Dectin-1 gene promoter. With a luciferase reporter gene driven by the Dectin-1 gene promoter, the expression of the PU.1 gene in NIH 3T3 cells was found to enhance the luciferase activity in a dose-dependent manner. PU.1 expression knockdown by small interfering RNA (siRNA) caused a 63% decrease in Dectin-1 mRNA level and 40% decrease in protein level in AMs. Results of this study indicate that downregulation of PU.1 during Pneumocystis pneumonia leads to decreased expression of Dectin-1 in AMs.
Dectin-1 是一种识别真菌β-葡聚糖的重要巨噬细胞吞噬受体。在这项研究中，发现在肺炎球菌感染的小鼠肺泡巨噬细胞（AMs）中，Dectin-1 基因的 mRNA 水平降低了 61%。这些细胞表面的 Dectin-1 蛋白表达也显著降低。通过荧光原位杂交，还发现肺炎球菌感染的 AMs 中转录因子 PU.1 的 mRNA 表达水平也显著降低。电泳迁移率变动分析显示，PU.1 蛋白与 Dectin-1 基因启动子结合。用由 Dectin-1 基因启动子驱动的荧光素酶报告基因，发现 NIH 3T3 细胞中 PU.1 基因的表达以剂量依赖性方式增强荧光素酶活性。通过小干扰 RNA（siRNA）敲低 PU.1 表达，导致 AMs 中 Dectin-1 mRNA 水平降低 63%，蛋白水平降低 40%。这项研究的结果表明，在肺炎球菌肺炎期间，PU.1 的下调导致 AMs 中 Dectin-1 的表达降低。
