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BioMed Research International
Volume 2017, Article ID 8727434, 7 pages
Research Article

Identification and Characterization of a Splicing Variant in the 5′ UTR of the Human TLR5 Gene

Department of Life Science, Gachon University, Seongnam, Gyeonggi-do 461-701, Republic of Korea

Correspondence should be addressed to Jae Young Kim;

Received 6 May 2017; Revised 2 August 2017; Accepted 2 August 2017; Published 29 August 2017

Academic Editor: Torsten Goldmann

Copyright © 2017 Thi Xoan Hoang 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.


Toll-like receptors (TLRs) are essential components of the innate immune system. TLR5 is the receptor for flagellin, the principal protein component of bacterial flagella. The TLR5 gene has 6 exons. In an RT-PCR analysis, we found long TLR5 transcripts, in addition to those of the expected size (short TLR5 transcripts). A sequence analysis revealed that the long TLR5 transcripts contain a new exon of 94 nucleotides located between previously reported exons IV and V in the 5′ untranslated region (5′ UTR). A real-time PCR analysis of the two alternatively spliced variants in various cell lines showed that the long TLR5 transcripts are abundantly expressed in nonimmune cells. The ratios of long/short transcripts in human nonimmune cell lines, such as A549, T98G, HaCaT, H460, HEK-293, and Caco-2 cells, and primary mesenchymal stem cells were in the range of 1.25 to 4.31. In contrast, those of human monocytic THP-1 and U937 cells and E6.1 T cells and Ramos B cells were around 0.9. These ratios in human monocytic THP-1 cells were decreased by treatment with IFN-γ in a concentration-dependent manner. Based on our findings, we suggest that the newly found long TLR5 transcripts may be involved in the negative regulation of TLR5 expression and function.