Knockdown of ketohexokinase versus inhibition of its kinase activity exert divergent effects on fructose metabolism

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.

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Publication Details

Journal
JCI Insight
Published
2024-10-17
DOI
https://doi.org/10.1172/jci.insight.184396
Citations
11
Primary Topic
Diet, Metabolism, and Disease
Type
article
Field-Weighted Citation Impact
3.93

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article

Knockdown of ketohexokinase versus inhibition of its kinase activity exert divergent effects on fructose metabolism

Sunhee Jung, Cholsoon Jang, Lindsey R. Conroy, Jérémie Boucher et al.
11 citations
JCI Insight
Diet, Metabolism, and Disease
3.93
article

Knockdown of ketohexokinase versus inhibition of its kinase activity exert divergent effects on fructose metabolism

Sunhee Jung, Cholsoon Jang, Lindsey R. Conroy, Jérémie Boucher, Alessandro Boianelli, Harrison A. Clarke, Senad Divanovic, Evelyn Bates, Ramon C. Sun, Gavin O’Mahony, Terry D. Hinds, Samir Softic, Zachary A. Kipp, Taghreed Fadhul, Genesee J. Martinez, Sehyung Park, Analia S. Loria, Kristina Wallenius, Marie Persson
article en
11 citations

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.

JCI InsightVol. 9(23)
Cincinnati Children's Hospital Medical Center (US), Joslin Diabetes Center (US), Harvard University (US), University of Kentucky (US), University of California, Irvine (US), University of Florida (US), AstraZeneca (Netherlands) (NL), AstraZeneca (Finland) (FI), Irvine University (US), AstraZeneca (Sweden) (SE), Pediatrics and Genetics (US), Institute of Medicinal Plant Development (CN), AstraZeneca (Germany) (DE), University of Gothenburg (SE)
AstraZeneca, Alnylam Pharmaceuticals, University of Kentucky
Zero hunger
Openalex Percentile: Top 5%
Diet, Metabolism, and Disease
3.93
DOIOpen Access PDFOpenAlex
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