Long-term Oral Administration of an HNF4α Agonist Prevents Weight Gain and Hepatic Steatosis by Promoting Increased Mitochondrial Mass and Function

We report here that the potent HNF4α agonist N-trans-caffeoyltyramine (NCT) promotes weight loss by inducing an increase in mitochondrial mass and function, including fatty acid oxidation. Previously, we found in a short term trial in obese mice that NCT promoted reversal of hepatic steatosis through a mechanism involving the stimulation of lipophagy by dihydroceramides. NCT led to increased dihydroceramide levels by inhibiting dihydroceramide conversion to ceramides. Here, we were able to administer NCT orally, permitting longer term administration. Mice fed NCT mixed with high fat diet exhibited decreased weight. Examination of RNA-seq data revealed an increase in PPARGC1A, a central regulator of mitochondrial biogenesis. In addition to the decreased hepatic steatosis that we found previously, mice fed a high fat diet containing NCT mice weighed substantially less than control mice fed high fat diet alone. They had increased mitochondrial mass, exhibited increased fatty acid oxidation, and had an increased level of NAD. Markers of liver inflammation such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα), which are important in the progression of non-alcoholic fatty liver disease to non-alcoholic steatohepatitis were decreased by NCT. There was no evidence of any toxicity from NCT consumption. These results indicate that HNF4α is an important regulator of mitochondrial mass and function and support that use of HNF4α to treat disorders of fatty acid excess, potentially including obesity, NAFLD, and NASH.