A functional cross-talk between liver X receptor-α and constitutive androstane receptor links lipogenesis and xenobiotic responses
| Autor: | Shaheen Khadem, Yonggong Zhai, Taira Wada, Song Li, Wen Xie, Songrong Ren, Ramalinga Kuruba, Bin Zhang |
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| Rok vydání: | 2010 |
| Předmět: |
Agonist
medicine.medical_specialty medicine.drug_class Pyridines Receptors Cytoplasmic and Nuclear Mice Transgenic Biology digestive system Xenobiotics Mice Internal medicine Constitutive androstane receptor medicine polycyclic compounds Animals Receptor Liver X receptor Cells Cultured Constitutive Androstane Receptor Liver X Receptors Pharmacology Mice Knockout Lipogenesis Receptor Cross-Talk Articles Orphan Nuclear Receptors Mice Inbred C57BL Endocrinology Nuclear receptor Molecular Medicine lipids (amino acids peptides and proteins) Female Chromatin immunoprecipitation human activities |
| Zdroj: | Molecular pharmacology. 78(4) |
| ISSN: | 1521-0111 |
| Popis: | The liver X receptor (LXR) and constitutive androstane receptor (CAR) are two nuclear receptors postulated to have distinct functions. LXR is a sterol sensor that promotes lipogenesis, whereas CAR is a xenosensor that controls xenobiotic responses. Here, we show that LXRα and CAR are functionally related in vivo. Loss of CAR increased the expression of lipogenic LXR target genes, leading to increased hepatic triglyceride accumulation, whereas activation of CAR inhibited the expression of LXR target genes and LXR ligand-induced lipogenesis. On the other hand, a combined loss of LXR α and β increased the basal expression of xenobiotic CAR target genes, whereas activation of LXR inhibited the expression of CAR target genes and sensitized mice to xenobiotic toxicants. The mutual suppression between LXRα and CAR was also observed in cell culture and reporter gene assays. LXRα, like CAR, exhibited constitutive activity in the absence of an exogenously added ligand by recruiting nuclear receptor coactivators. Interestingly, although CAR competed with LXRα for coactivators, the constitutive activity and recruitment of coactivators was not required for CAR to suppress the activity of LXRα. In vivo chromatin immunoprecipitation assay showed that cotreatment of a CAR agonist compromised the LXR agonist responsive recruitment of LXRα to Srebp-1c, whereas an LXR agonist inhibited the CAR agonist-responsive recruitment of CAR to Cyp2b10. In conclusion, our results have revealed dual functions of LXRα and CAR in lipogenesis and xenobiotic responses, establishing a unique role of these two receptors in integrating xenobiotic and endobiotic homeostasis. |
| Databáze: | OpenAIRE |
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