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Journal of Biomedicine and Biotechnology
Volume 2012 (2012), Article ID 648170, 6 pages
http://dx.doi.org/10.1155/2012/648170
Research Article

Triiodothyronine Represses MUC5AC Expression by Antagonizing Sp1 Binding to Its Promoter in Human Bronchial Epithelial HBE16 Cells

1Division of Respiratory Medicine, Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, China
2Far Eastern Scientific Center of Physiology and Pathology of Respiration, Siberian Branch, Russian Academy of Medical Sciences, 675000 Blagoveschensk, Russia

Received 27 August 2011; Revised 9 November 2011; Accepted 9 November 2011

Academic Editor: Anton M. Jetten

Copyright © 2012 Xiaolong Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Mucus hypersecretion is a distinguished feature of chronic inflammatory airway diseases. Interestingly, in this condition thyroid function is impaired with decreased level of triiodothyronine (T3), indicating potential link between low level of T3 and mucus hypersecretion. But the underlying mechanisms are poorly understood. In this study we aimed to elucidate the effect of T3 on MUC5AC secretion in human bronchial epithelial HBE16 cells and further investigate how T3 regulates MUC5AC gene expression at transcriptional level. By RT-PCR and ELISA we showed that T3 inhibited MUC5AC mRNA expression and protein secretion in HBE16 cells. Furthermore, luciferase assay and site-directed mutagenesis analysis demonstrated that T3 repressed MUC5AC expression at transcriptional level and the mechanism might partly lie in the specific inhibition of Sp1 binding to the promoter. Our results suggest that decreased T3 level leads to the release of repression of MUC5AC expression and thus contributes to mucus hypersecretion.