Differential Metabolic and Multi-tissue Transcriptomic Responses to Fructose Consumption among Genetically Diverse Mice [Hypothalamus]

The escalating prevalence of metabolic syndrome (MetS) poses significant risks to type 2 diabetes mellitus, cardiovascular diseases, and non-alcoholic fatty liver disease. High fructose intake has emerged as an environmental risk for MetS and the associated metabolic diseases. To examine inter-individual variability in MetS susceptibility in response to fructose consumption, here we fed three inbred mouse strains, namely C57BL/6J (B6), DBA (DBA) and FVB/NJ (FVB) with 8% fructose in drinking water for 12 weeks. We found that fructose-fed DBA mice had significantly higher amount of body weight, adiposity, and glucose intolerance starting from the 4th week of fructose feeding compared to the control group, while B6 and FVB showed no differences in these phenotypes over the course of fructose feeding. In addition, elevated insulin levels were found in fructose-fed DBA and FVB mice, and cholesterol levels were uniquely elevated in B6 mice. To explore the molecular underpinnings of the observed distinct phenotypic responses among strains, we applied RNA sequencing to investigate the effect of fructose on the transcriptional profiles of liver and hypothalamus tissues, revealing strain- and tissue-specific patterns of transcriptional and pathway perturbations. Strain-specific liver pathways altered by fructose include fatty acid and cholesterol metabolic pathways for B6 and PPAR signaling for DBA. In hypothalamus tissue, only B6 showed significantly enriched pathways such as protein folding, pancreatic secretion, and fatty acid beta-oxidation. Using network modeling, we predicted potential strain-specific key regulators of fructose response such as Fgf21 (DBA) and Lss (B6) in liver, and Fmod (B6) in hypothalamus. We validated strain-biased responses of Fgf21 and Lss to fructose in primary hepatocytes. Our findings support that fructose perturbs different tissue networks and pathways in genetically diverse mice and associates with distinct features of metabolic dysfunctions. These results highlight individualized molecular and metabolic responses to fructose consumption and may help guide the development of personalized strategies against fructose-induced MetS. Male DBA, B6 and FVB mice (Jackson Laboratory) of 7 weeks old weighing 20-25 g were randomly assigned to 8% fructose treatment (n=8-12, 8% w/v fructose in the drinking water) and control group (n=8-10, drinking water) for 14 weeks. We chose 8% fructose to mimic the average fructose consumption found in sugar-sweetened beverages (~10% w/v) consumed in humans. Mice had free access to water and diets and were maintained under standard housing condition (room temperature 22-24 ??C) with 12 h light/dark cycle. Daily food and drink intake were monitored on per-cage basis. The mice were examined for changes in metabolic phenotypes including body weight, body fat, lean mass, intraperitoneal glucose tolerance test (IPGTT), and serum levels of insulin, glucose, total cholesterol (TC), high density lipoprotein cholesterol (HDL), un-esterified cholesterol, free fatty acids (FFA), and triglycerides (TG), as detailed in the following sections. Mice were sacrificed at the end of the 14-week fructose treatment experiment, and hypothalamus and liver tissues were dissected out, flash frozen and stored at ?70??C until use.