Biotechnology of Human Disorders
  Molecular Biology and Genetics
Electronic Journal of Biotechnology ISSN: 0717-3458 Vol. 14 No. 3, Issue of May 15, 2011
© 2011 by Pontificia Universidad Católica de Valparaíso -- Chile Received November 25, 2010 / Accepted March 24, 2011
DOI: 10.2225/vol14-issue3-fulltext-9   
RESEARCH ARTICLE

Rapamycin pre-treatment abrogates Tumour Necrosis Factor-α down-regulatory effects on LXR-α and PXR mRNA expression via inhibition of c-Jun N-terminal kinase 1 activation in HepG2 cells

Di-Lin Ng1 · Shin-Wei Tie2 · Pei-Chin Ong1 · Wyi-Sian Lim2 · Tengku-Sifzizul Tengku-Muhammad3 · Quok-Cheong Choo1 · Choy-Hoong Chew*2

1 Department of Biological Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, Kampar, Perak, Malaysia
2 Department of Biomedical Science, Faculty of Science, Universiti Tunku Abdul Rahman, Jalan Universiti, Bandar Barat, Kampar, Perak, Malaysia
3 Department of Biological Science, Faculty of Science and Technology, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu, Malaysia

*Corresponding author: chewch@utar.edu.my

Financial support: This study is supported in parts by E-Science Fund (02-02-11-SF0039) by the Malaysia’s Ministry of Science, Technology and Innovation (MOSTI).

Keywords: Akt, c-Jun, homeostasis, inflammation, MKK7, transcription factor.

Abstract    

The Liver X Receptor (LXR) and Pregnane X Receptor (PXR) are members of the nuclear receptor superfamily. Previously, they have been classified as important regulators of lipid homeostasis. However, recent studies have shown that they may be implicated in anti-inflammatory responses as well. This study shows that Tumour Necrosis Factor-α (TNF-α) treatment reduces both LXR-α and PXR mRNA expression. However, pre-treatment with rapamycin, an mTOR inhibitor, followed by TNF-α stimulation, significantly induces LXR-α and PXR mRNA expression to ~17- and ~2-fold, respectively. This suggests that mTORC1, a multi-molecular complex of which mTOR is a member, may act as a negative regulator that inhibits the induction of LXR-α and PXR as anti-inflammatory genes. It is also shown here that inhibition of JNK1 via the mTOR/Akt pathway coincides with the up-regulation of LXR-α and PXR mRNA, after TNF-α treatment. Together, these observations suggest that JNK1 possibly act downstream of mTORC1 as an LXR-α and PXR inhibitor. From the results gleaned in this study, rapamycin (and its analogues) may be used to reduce acute inflammation by promoting the induction of LXR-α and PXR as anti-inflammatory genes.