Down-regulation of granulocyte-macrophage colony-stimulating factor by 3C-like proteinase in transfected A549 human lung carcinoma cells

• Main Authors: Tsai Hsien-Yu, Chen Miles, Wang Yao-Chen, Liao Hsien-Hua, Lin Johnson, Chen Shui-Tein, Tsay Gregory, Cheng Sun-Long
• Format: Article
• Language: English
• Published: BMC 2011-02-01
• Series: BMC Immunology
• Online Access: http://www.biomedcentral.com/1471-2172/12/16

<p>Abstract</p> <p>Background</p> <p>Severe Acute Respiratory Syndrome (SARS) is a severe respiratory illness caused by a novel virus, the SARS coronavirus (SARS-CoV). 3C-like protease (3CL^pro) of SARS-CoV plays a role in processing viral polypeptide precursors and is responsible of viral maturation. However, the function of 3CL^proin host cells remains unknown. This study investigated how the 3CL^proaffected the secretion of cytokines in the gene-transfected cells.</p> <p>Results</p> <p>From immunofluorescence microscopy, the localization of c-myc tagged 3CL^prowas detected both in the cytoplasm and nucleus of transfected A549 cells. Expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) was significantly decreased in 3CL^pro-transfected cells by both RT-PCR and ELISA, but without changes in other cytokines, <it>i.e</it>., IL-1β, IL-6, IL-8, IL12p40, TNF-α, and TGF-β. Furthermore, the protein levels of NF-kB decreased in 3CL^pro-transfected A549 cells when compared to EGFP transfected cells.</p> <p>Conclusions</p> <p>Our results suggest that the 3CL^promay suppress expression of GM-CSF in transfected A549 cells through down-regulation of NF-kB production.</p>