Binding of upstream stimulatory factor 1 to the E-Box regulates the 4G/5G polymorphism–dependent plasminogen activator inhibitor 1 expression in mast cells

• Published in: Journal of allergy and clinical immunology 2008-04, Vol.121 (4), p.1006-1012.e2
• Main Authors: Ma, Zhongcai, PhD, Jhun, BongSook, PhD, Jung, Sandy Y., MD, Oh, Chad K., MD
• Format: Article
• Language: English
• Subjects: 4G/5G polymorphism; Alleles; Allergy and Immunology; Asthma; Asthma - genetics; Asthma - metabolism; Asthma - pathology; Biological and medical sciences; Cell Line; Colleges & universities; E-box; E-Box Elements - genetics; E-Box Elements - physiology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Genes; Genotype & phenotype; Guanine Nucleotides - genetics; Guanine Nucleotides - metabolism; human mast cells; Humans; Immunopathology; Mast Cells - immunology; Mast Cells - metabolism; Medical sciences; Mutagenesis; Plasmids; Plasminogen activator inhibitor 1; Plasminogen Activator Inhibitor 1 - biosynthesis; Plasminogen Activator Inhibitor 1 - genetics; Plasminogen Activator Inhibitor 1 - metabolism; Polymorphism, Genetic - physiology; Protein Binding - genetics; Regulation; Rodents; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; transcription; Transcription factors; Up-Regulation - genetics; upstream stimulatory factor 1; Upstream Stimulatory Factors - biosynthesis; Upstream Stimulatory Factors - genetics; Upstream Stimulatory Factors - metabolism
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2007.11.015

Background Plasminogen activator inhibitor (PAI)–1 is a key regulator of the fibrinolytic system. PAI-1 levels are markedly elevated in the asthmatic airways. The 4G/5G polymorphism of the PAI-1 gene is associated with allergic asthma. Objective To characterize the mechanisms of the 4G/5G-dependent PAI-1 expression in mast cells (MCs), a major source of PAI-1 and key effector cells in asthma. Methods Transcription of PAI-1 was assessed by transiently transfecting human MC line (HMC-1) cells with the luciferase-tagged PAI-1 promoters containing the 4G or 5G allele (4G–PAI-1 or 5G–PAI-1 promoter). Upstream stimulatory factor (USF)–1 and the E-box interactions were studied by electrophoretic mobility shift assays and supershift assays. Expression of USF-1 was determined by Western blot analysis. Results The 4G–PAI-1 promoter has higher promoter activity than the 5G–PAI-1 promoter in stimulated HMC-1 cells, and the E-box adjacent to the 4G/5G site (E-4G/5G) regulates the genotype-specific PAI-1 transcription. USF-1 binds to the E-4G with greater affinity than to the E-5G. USF-1 level is increased in HMC-1 cells after stimulation, and elevated USF-1 enhances PAI-1 transcription. Overexpression of wild-type USF-1 or dominant-negative USF remedies the 4G/5G-dependent PAI-1 transcription. Conclusion Binding of USF-1 to the E-4G/5G regulates the 4G/5G polymorphism–dependent PAI-1 expression in MCs.