| First Author | Gullberg H | Year | 2000 |
| Journal | Mol Endocrinol | Volume | 14 |
| Issue | 11 | Pages | 1739-49 |
| PubMed ID | 11075809 | Mgi Jnum | J:125475 |
| Mgi Id | MGI:3758564 | Doi | 10.1210/mend.14.11.0548 |
| Citation | Gullberg H, et al. (2000) Thyroid hormone receptor beta-deficient mice show complete loss of the normal cholesterol 7alpha-hydroxylase (CYP7A) response to thyroid hormone but display enhanced resistance to dietary cholesterol. Mol Endocrinol 14(11):1739-49 |
| abstractText | Thyroid hormone (T3) influences hepatic cholesterol metabolism, and previous studies have established an important role of this hormone in the regulation of cholesterol 7alpha-hydroxylase (CYP7A), the rate-limiting enzyme in the synthesis of bile acids. To evaluate the respective contribution of thyroid hormone receptors (TR) alpha1 and beta in this regulation, the responses to 2% dietary cholesterol and T3 were studied in TRalpha1 and TRbeta knockout mice under hypo- and hyperthyroid conditions. Our experiments show that the normal stimulation in CYP7A activity and mRNA level by T3 is lost in TRbeta-/- but not in TRalpha1-/-mice, identifying TRbeta as the mediator of T3 action on CYP7A and, consequently, as a major regulator of cholesterol metabolism in vivo. Somewhat unexpectedly, T3-deficient TRbeta-/- mice showed an augmented CYP7A response after challenge with dietary cholesterol, and these animals did not develop hypercholesterolemia to the extent as did wild-type (wt) controls. The latter results lend strong support to the concept that TRs may exert regulatory effects in vivo independent of T3. |
