Abstract
Excessive fructose intake is a risk factor for the development of obesity and its complications. Targeting ketohexokinase (KHK), the first enzyme of fructose metabolism, has been investigated for the management of metabolic dysfunction–associated steatotic liver disease (MASLD). We compared the effects of systemic, small molecule inhibitor of KHK enzymatic activity with hepatocyte-specific, N-acetylgalactosamine siRNA–mediated knockdown of KHK in mice on an HFD. We measured KHK enzymatic activity, extensively quantified glycogen accumulation, performed RNA-Seq analysis, and enumerated hepatic metabolites using mass spectrometry. Both KHK siRNA and KHK inhibitor led to an improvement in liver steatosis; however, via substantially different mechanisms, KHK knockdown decreased the de novo lipogenesis pathway, whereas the inhibitor increased the fatty acid oxidation pathway. Moreover, KHK knockdown completely prevented hepatic fructolysis and improved glucose tolerance. Conversely, the KHK inhibitor only partially reduced fructolysis, but it also targeted triokinase, mediating the third step of fructolysis. This led to the accumulation of fructose-1 phosphate, resulting in glycogen accumulation, hepatomegaly, and impaired glucose tolerance. Overexpression of wild-type, but not kinase-dead, KHK in cultured hepatocytes increased hepatocyte injury and glycogen accumulation after treatment with fructose. The differences between KHK inhibition and knockdown are, in part, explained by the kinase-dependent and -independent effects of KHK on hepatic metabolism.
Document Type
Article
Publication Date
10-2024
Digital Object Identifier (DOI)
https://doi.org/10.1172/jci.insight.184396
Funding Information
The authors would like to thank Leila Noetzli, Ho-Chou Tu, and Kevin Fitzgerald at Alnylam Pharmaceutical for their assistance with the project. Additionally, we thank Mark Keibler for quantifying F1P in vivo. We greatly appreciate Terry Flier and Anna Borodovsky at Alnylam for critically reading the manuscript. Next, we would like to thank Jian-Ming Liu for measuring the in vitro potency of the inhibitor and Sara Lindblom for formulating the inhibitor for oral administration at AstraZeneca. We thank Gregory Graft (University of Kentucky) for providing ABCD2 antibody. We thank the Biopolymers Facility Genomics Core Facility at Harvard Medical School for their expertise and instrument availability that supported RNA-Seq work. This work was supported in part by the North American Society For Pediatric Gastroenterology, Hepatology & Nutrition Foundation Young Investigator Award, Pediatric Scientist Development Program Award (HD000850), and Center of Research in Obesity and Cardiovascular Disease Pilot and Feasibility Grant (GM127211) awarded to SS. Alnylam Pharmaceutical funded this work, in part, via a sponsored research agreement awarded to SS. This research was supported by the University of Kentucky Office of the Vice President for Research through the Diabetes and Obesity Research Priority Area
Repository Citation
Park, Se-Hyung; Fadhul, Taghreed; Conroy, Lindsey R.; Clarke, Harrison A.; Sun, Ramon; Wallenius, Kristina; Boucher, Jeremie; O'Mahony, Gavin; Boianelli, Alessandro; Persson, Marie; Jung, Sunhee; Jang, Cholsoon; Loria, Analia S.; Martinez, Genesee J.; Kipp, Zachary A.; Bates, Evelyn A.; Hinds, Terry D. Jr.; Divanovic, Senad; and Softic, Samir, "Knockdown of ketohexokinase versus inhibition of its kinase activity exert divergent effects on fructose metabolism" (2024). Markey Cancer Center Faculty Publications. 277.
https://uknowledge.uky.edu/markey_facpub/277
Included in
Biochemical Phenomena, Metabolism, and Nutrition Commons, Biochemistry Commons, Oncology Commons
Notes/Citation Information
© 2024, Park et al. This is an open access article published under the terms of the Creative Commons Attribution 4.0 International License.