title: Interplay between FGF21 and insulin action in the liver regulates metabolism.
abstract: The hormone FGF21 regulates carbohydrate and lipid homeostasis as well as body weight, and increasing FGF21 improves metabolic abnormalities associated with obesity and diabetes. FGF21 is thought to act on its target tissues, including liver and adipose tissue, to improve insulin sensitivity and reduce adiposity. Here, we used mice with selective hepatic inactivation of the IR (LIRKO) to determine whether insulin sensitization in liver mediates FGF21 metabolic actions. Remarkably, hyperglycemia was completely normalized following FGF21 treatment in LIRKO mice, even though FGF21 did not reduce gluconeogenesis in these animals. Improvements in blood sugar were due in part to increased glucose uptake in brown fat, browning of white fat, and overall increased energy expenditure. These effects were preserved even after removal of the main interscapular brown fat pad. In contrast to its retained effects on reducing glucose levels, the effects of FGF21 on reducing circulating cholesterol and hepatic triglycerides and regulating the expression of key genes involved in cholesterol and lipid metabolism in liver were disrupted in LIRKO mice. Thus, FGF21 corrects hyperglycemia in diabetic mice independently of insulin action in the liver by increasing energy metabolism via activation of brown fat and browning of white fat, but intact liver insulin action is required for FGF21 to control hepatic lipid metabolism.
authors.forename: Brice
authors.initials: B
authors.lastname: Emanuelli
authors.forename: Sara G
authors.initials: SG
authors.lastname: Vienberg
authors.forename: Graham
authors.initials: G
authors.lastname: Smyth
authors.forename: Christine
authors.initials: C
authors.lastname: Cheng
authors.forename: Kristin I
authors.initials: KI
authors.lastname: Stanford
authors.forename: Manimozhiyan
authors.initials: M
authors.lastname: Arumugam
authors.forename: Mervyn D
authors.initials: MD
authors.lastname: Michael
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Adams
authors.forename: Alexei
authors.initials: A
authors.lastname: Kharitonenkov
authors.forename: C Ronald
authors.initials: CR
authors.lastname: Kahn
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D002784:Cholesterol / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D005786:Gene Expression Regulation; D006943:Hyperglycemia / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000235:genetics; D008055:Lipids / Q000737:chemistry; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009929:Organ Size; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; C414620:fibroblast growth factor 21; D005346:Fibroblast Growth Factors; D002784:Cholesterol