NIF LinkOut Portal

Options
Only Pubmed Central
Include Pubmed Central
Sections
Title
Abstract
Introduction
Methods
Results
Supplement
Appendix
Contributions
Background
Commentary
Funding
Limitations
Caption
FILTERS

RBCK1, an E3 ubiquitin ligase, interacts with and ubiquinates the human pregnane X receptor.

Authors:
Rana R, Coulter S, Kinyamu H, Goldstein JA
Affiliation:
Journal:
Drug metabolism and disposition: the biological fate of chemicals

Abstract

The pregnane X receptor (PXR, NR1I2) plays a pivotal role in the disposition and detoxification of numerous foreign and endogenous chemicals by increasing transcription of numerous target genes, including phase I and II drug-metabolizing enzymes and transporters. In the present study, yeast two-hybrid screening identified an E3 ubiquitin ligase, RBCK1 (Ring-B-box-coiled-coil protein interacting with protein kinase C-1), as a human pregnane X receptor (hPXR)-interacting protein. Coimmunoprecipitation studies confirmed the interaction between RBCK1 and hPXR when both were ectopically expressed in AD-293 cells. Domain mapping studies showed that the interaction between RBCK1 and hPXR involves all RBCK1 domains. We further demonstrate that RBCK1 ubiquitinates hPXR, and this may target hPXR for degradation by the ubiquitin-proteasome pathway. Simultaneous ectopic overexpression of RBCK1 and PXR decreased PXR levels in AD-293 cells, and this decrease was inhibited by the proteasomal inhibitor MG-132 (carbobenzoxy-Leu-Leu-leucinal). Furthermore, overexpression of RBCK1 decreased endogenous levels of PXR in HepG2 cells. Of importance, ectopic overexpression and silencing of endogenous RBCK1 in primary human hepatocytes resulted in a decrease and increase, respectively, in endogenous PXR protein levels and in the induction of PXR target genes by rifampicin. These results suggest that RBCK1 is important for the ubiquitination of PXR and may play a role in its proteasomal degradation.

  1. Welcome

    Welcome to NIF. Explore available research resources: data, tools and materials, from across the web

  2. Community Resources

    Search for resources specially selected for NIF community

  3. More Resources

    Search across hundreds of additional biomedical databases

  4. Literature

    Search Pub Med abstracts and full text from PubMed Central

  5. Insert your Query

    Enter your search terms here and hit return. Search results for the selected tab will be returned.

  6. Join the Community

    Click here to login or register and join this community.

  7. Categories

    Narrow your search by selecting a category. For additional help in searching, view our tutorials.

  8. Query Info

    Displays the total number of search results. Provides additional information on search terms, e.g., automated query expansions, and any included categories or facets. Expansions, filters and facets can be removed by clicking on the X. Clicking on the + restores them.

  9. Search Results

    Displays individual records and a brief description. Click on the icons below each record to explore additional display options.

X