Transcription regulation of nuclear receptor PXR: Role of SUMO-1 modification and NDSM in receptor function. (15th January 2016)

• Record Type: Journal Article
• Authors: Priyanka, ; Kotiya, Deepak; Rana, Manjul; Subbarao, N.; Puri, Niti; Tyagi, Rakesh K.
• Is Part Of: Molecular and cellular endocrinology. Volume 420(2016)
• Page Start: 194
• Page End: 207
• Publication Date: 2016-01-15
• Subjects: Nuclear receptor -- SUMOylation -- PXR -- Transcription factor -- Xenobiotic metabolism; Endocrinology -- Periodicals; Molecular biology -- Periodicals; Cytology -- Periodicals; Endocrinology -- Periodicals; Hormones -- Periodicals; Endocrinologie -- Périodiques; Cytology; Endocrinology; Molecular biology; Periodicals; 573.4
• DOI: 10.1016/j.mce.2015.11.001
• Languages: English
• ISSNs: 0303-7207

Abstract

Abstract: Pregnane & Xenobiotic Receptor (PXR) is one of the 48 members of the nuclear receptor superfamily of ligand-modulated transcription factors. PXR plays an important role in metabolism and elimination of diverse noxious endobiotics and xenobiotics. Like in case of some nuclear receptors its function may also be differentially altered, positively or negatively, by various post-translational modifications. In this context, regulation of PXR function by SUMOylation is the subject of present investigation. Here, we report that human PXR is modified by SUMO-1 resulting in its enhanced transcriptional activity. RT-PCR analysis showed that PXR SUMOylation in presence of rifampicin also enhances the endogenous expression levels of key PXR-regulated genes like CYP3A4, CYP2C9, MDR1 and UGT1A1. In addition, mammalian two-hybrid assay exhibited enhanced interaction between PXR and co-activator SRC-1. EMSA results revealed that SUMOylation has no influence on the DNA binding ability of PXR. In silico analysis suggested that PXR protein contains four putative SUMOylation sites, centered at K108, K129, K160 and K170. In addition to this, we identified the presence of NDSM (N egative charge amino acidD ependentS UMOylationM otif) in PXR. Substitution of all its four putative lysine residues along with NDSM abolished the effect of SUMO-1-mediated transactivation function of PXR. Furthermore, we show that interaction between PXR and E2-conjugation enzyme UBCh9, an important step for implementation of SUMOylation event, was reduced in case of NDSM mutant PXRD115A. Overall, our results suggest that SUMOylation at specific sites on PXR protein are involved in enhancement of transcription function of this receptor. Highlights: PTMs regulate transcriptional function of nuclear receptors, including PXR. We show that modification by SUMO-1 enhances PXR transcription function. We observe that disruption of SUMO motif attenuates PXR transcriptional activity. We report existence and involvement of NDSM in PXR transcriptional regulation. SUMOylation at specific sites regulates PXR transcription function.