Xiao-jun LI^1,2,3, Kikumi HATA³, Junichiro MIZUGUCHI³

²Department of Medical Laboratory Science, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, 210002, China; ³Department of Immunology and Intractable Disease Research Center, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, 160-8402, Tokyo, Japan

Aim: We have recently shown that engagement of membrane immunoglobulin (mIg) induced upregulation of inhibitor of differentiation 3 (Id3) mRNA, resulting in growth arrest at G1 phase in WEHI-231 cells. In the present study, we examined whether engagement of mIg will affect promoter activity of the Id3 gene in WEHI-231 cells.

Methods:  An asthma model was sensitized and challenged by ovalbumin (OVA) in male C57BL/6 mice. Asthmatic mice were given dual administration (intraperitoneal injection and aerosol inhalation) of CCR3 mAb or nonspecific rat IgG (ns-IgG). The number of total and differential inflammatory cells in the bronchial alveolar lavage fluid (BALF) was counted. Eosinophils number, the goblet cell percentage (GCP) and airway mucus index (AMI) were measured in the lung tissues. Interleukin (IL)-5 levels in the BALF were examined. The expression of MUC5AC and the epidermal growth factor receptor (EGFR) mRNA in the lung tissues was detected by semi-quantitative RT-PCR. The results were compared among the groups.

Results: The luciferase analysis demonstrated that basal promoter activity of the Id3 gene was found in the region between -200 and +54. The Id3 promoter activity was increased 2-fold following stimulation with anti-IgM, but not CD40L, compared with medium alone.

Conclusion: The mIg-mediated upregulation of Id3 expression is controlled, at least in part, through transcriptional regulation, as assessed by luciferase assay.