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Open Access Highly Accessed Research article

Functional characterization of the ER stress induced X-box-binding protein-1 (Xbp-1) in the porcine system

Jin-Yu Zhang12, Kyu-Sun Lee1, Ji-Su Kim3, Bong-Seok Song3, Dong-Il Jin2, Deog-Bon Koo4* and Kweon Yu1*

Author Affiliations

1 Aging Research Centre, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, Korea

2 Dept. Animal Science, Chungnam National University, Daejeon, Korea

3 National Primate Research Center, KRIBB, Ochang, Chungbuk Korea

4 Dept. of Biotechnology, Daegu University, Gyeongbuk, Korea

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BMC Molecular Biology 2011, 12:25  doi:10.1186/1471-2199-12-25

Published: 24 May 2011

Abstract

Background

The unfolded protein response (UPR) is an evolutionary conserved adaptive reaction for increasing cell survival under endoplasmic reticulum (ER) stress conditions. X-box-binding protein-1 (Xbp1) is a key transcription factor of UPR that activates genes involved in protein folding, secretion, and degradation to restore ER function. The UPR induced by ER stress was extensively studied in diseases linked to protein misfolding and aggregations. However, in the porcine system, genes in the UPR pathway were not investigated. In this study, we isolated and characterized the porcine Xbp1 (pXbp1) gene in ER stress using porcine embryonic fibroblast (PEF) cells and porcine organs. ER stress was induced by the treatment of tunicamycin and cell viability was investigated by the MTT assay. For cloning and analyzing the expression pattern of pXbp1, RT-PCR analysis and Western blot were used. Knock-down of pXbp1 was performed by the siRNA-mediated gene silencing.

Results

We found that the pXbp1 mRNA was the subject of the IRE1α-mediated unconventional splicing by ER stress. Knock-down of pXbp1 enhanced ER stress-mediated cell death in PEF cells. In adult organs, pXbp1 mRNA and protein were expressed and the spliced forms were detected.

Conclusions

It was first found that the UPR mechanisms and the function of pXbp1 in the porcine system. These results indicate that pXbp1 plays an important role during the ER stress response like other animal systems and open a new opportunity for examining the UPR pathway in the porcine model system.