Qin Hongwei, Edberg Jeffrey C, Gibson Andrew W, Page Grier P, Teng Lihong, Kimberly Robert P
Department of Medicine, University of Alabama at Birmingham, 1900 University Boulevard, Birmingham, AL 35294-0006, USA.
J Immunol. 2004 Nov 15;173(10):6211-9. doi: 10.4049/jimmunol.173.10.6211.
The cytoplasmic domain (CY) of the ligand-binding alpha-chain of the gamma-chain-associated FcRs can modulate receptor function such as phagocytosis, endocytosis, and intracellular trafficking of receptor-Ag complexes. To assess the potential role of the CY domain of human FcgammaRIa (CD64) alpha-chain in the transcriptional regulation of receptor-induced gene expression, we developed stably transfected murine macrophage cell lines expressing a full-length or a CY deletion mutant (tail-less) of human FcgammaRIa to analyze gene expression in response to receptor-specific cross-linking. Using the Affymetrix murine genome U74Av2 GeneChip array, we observed >100 candidate genes having > or =2-fold difference expression at 1.5 and 3 h after stimulation. Focusing on several immunologically related genes, we confirmed differential expression of M-CSF, macrophage inhibitory cytokine-1, leukocyte-specific protein 1, MIP-2, and IL-1R antagonist by RT-PCR and RNase protection assays. Analysis of mRNA stability indicated that the differential regulation of gene expression by the CY of the CD64 alpha-chain is at the level of gene transcription. Our results indicate that the CY of the CD64 alpha-chain modulates transcriptional activity induced by receptor-specific engagement in macrophages and provides a framework for understanding distinct expression profiles elicited by different Fc gamma-chain-associated receptors.
γ链相关Fc受体的配体结合α链的胞质结构域（CY）可调节受体功能，如吞噬作用、胞吞作用以及受体-抗原复合物的细胞内运输。为了评估人FcγRIa（CD64）α链的CY结构域在受体诱导的基因表达转录调控中的潜在作用，我们构建了稳定转染的小鼠巨噬细胞系，这些细胞系表达全长或CY缺失突变体（无尾）的人FcγRIa，以分析受体特异性交联后的基因表达。使用Affymetrix小鼠基因组U74Av2基因芯片阵列，我们观察到在刺激后1.5小时和3小时，有超过100个候选基因的表达差异≥2倍。聚焦于几个免疫相关基因，我们通过RT-PCR和核糖核酸酶保护试验证实了M-CSF、巨噬细胞抑制细胞因子-1、白细胞特异性蛋白1、MIP-2和IL-1R拮抗剂的差异表达。mRNA稳定性分析表明，CD64α链的CY对基因表达的差异调节发生在基因转录水平。我们的结果表明，CD64α链的CY调节巨噬细胞中受体特异性结合诱导的转录活性，并为理解不同的Fcγ链相关受体引发的不同表达谱提供了一个框架。
