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Updated: Aug 18, 2026

Measurement of Fatty Acid β-Oxidation in a Suspension of Freshly Isolated Mouse Hepatocytes
Published on: September 9, 2021
Thioesterase activity and acyl-CoA/fatty acid cross-talk of hepatocyte nuclear factor-4{alpha}
Rachel Hertz1, Bella Kalderon, Tamara Byk
1Department of Human Nutrition and Metabolism, Hebrew University Medical School, Ein-Kerem, P. O. Box 12272, Jerusalem 91120, Israel.
Abstract:
Hepatocyte nuclear factor-4alpha (HNF-4alpha) activity is modulated by natural and xenobiotic fatty acid and fatty acyl-CoA ligands as a function of their chain length, unsaturation, and substitutions. The acyl-CoA site of HNF-4alpha is reported here to consist of the E-F domain, to bind long-chain acyl-CoAs but not the respective free acids, and to catalyze the hydrolysis of bound fatty acyl-CoAs. The free acid pocket, previously reported in the x-ray structure of HNF-4alpha E-domain, entraps fatty acids but excludes acyl-CoAs. The acyl-CoA and free acid sites are distinctive and noncongruent. Free fatty acid products of HNF-4alpha thioesterase may exchange with free acids entrapped in the fatty acid pocket of HNF-4alpha. Cross-talk between the acyl-CoA and free fatty acid binding sites is abrogated by high affinity, nonhydrolyzable acyl-CoA ligands of HNF-4alpha that inhibit its thioesterase activity. Hence, HNF-4alpha transcriptional activity is controlled by its two interrelated acyl ligands and two binding sites interphased in tandem by the thioesterase activity. The acyl-CoA/free-acid and receptor/enzyme duality of HNF-4alpha extends the paradigm of nuclear receptors.
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