title: FIAT Deletion Increases Bone Mass But Does Not Prevent High-Fat-Diet-Induced Metabolic Complications.
abstract: Factor inhibiting activating transcription factor 4 (ATF4)-mediated transcription (FIAT) interacts with ATF4 to repress its transcriptional activity. We performed a phenotypic analysis of Fiat-deficient male mice (Fiat-/Y) at 8 and 16 weeks of age. Microcomputed tomography analysis of the distal femur demonstrated 46% and 13% age-dependent increases in trabecular bone volume and thickness, respectively, in Fiat-/Y mice. Cortical bone measurements at the femoral midshaft revealed a substantial increase in cortical thickness in older Fiat-/Y mice. Bone gain was related to increased mineral apposition rate and increased osteoblast function. Femoral stiffness and strength were substantially increased in Fiat-/Y compared with wild-type (WT) mice. We also investigated whether FIAT contributes to metabolic function. When fed standard mouse chow, Fiat-/Y animals were glucose-tolerant. However, when fed a high-fat diet (HFD) for 8 weeks, Fiat-/Y mice gained more weight than control mice, with a specific increase in white adipose tissue fat mass. The increase in fat mass was due to reduced energy expenditure, which correlated with reduced fatty acid oxidation and lipolysis in the adipose tissue of mutant mice. The expression of the Scd1 gene, involved in lipogenesis, was upregulated in the subcutaneous adipose tissue of Fiat-/Y mice. Moreover, HFD-fed Fiat-/Y mice exhibited increased circulating leptin and insulin levels relative to WT mice, demonstrating that endocrine abnormalities are associated with the disturbance in energy balance. We conclude that Fiat-/Y mice exhibited an anabolic bone phenotype but displayed increased susceptibility to developing metabolic-related disorders when consuming an HFD.
authors.affiliation: Research Centre, Shriners Hospital for Children-Canada, Montreal, Quebec, Canada.|Departments of Human Genetics, McGill University, Montreal, Quebec, Canada.
authors.forename: Bahareh
authors.initials: B
authors.lastname: Hekmatnejad
authors.affiliation: Research Centre, Shriners Hospital for Children-Canada, Montreal, Quebec, Canada.|Departments of Human Genetics, McGill University, Montreal, Quebec, Canada.
authors.forename: Vionnie W C
authors.initials: VW
authors.lastname: Yu
authors.affiliation: Research Centre, Shriners Hospital for Children-Canada, Montreal, Quebec, Canada.
authors.forename: William
authors.initials: W
authors.lastname: Addison
authors.affiliation: Research Centre, Shriners Hospital for Children-Canada, Montreal, Quebec, Canada.
authors.forename: Vice
authors.initials: V
authors.lastname: Mandic
authors.affiliation: Research Centre, Shriners Hospital for Children-Canada, Montreal, Quebec, Canada.|Departments of Human Genetics, McGill University, Montreal, Quebec, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Pellicelli
authors.affiliation: Research Centre, Shriners Hospital for Children-Canada, Montreal, Quebec, Canada.
authors.forename: Alice
authors.initials: A
authors.lastname: Arabian
authors.affiliation: Research Centre, Shriners Hospital for Children-Canada, Montreal, Quebec, Canada.|Departments of Human Genetics, McGill University, Montreal, Quebec, Canada.
authors.forename: René
authors.initials: R
authors.lastname: St-Arnaud
mesh_terms: D052436:Adipose Tissue, White / Q000378:metabolism; D050154:Adiposity; D000367:Age Factors; D000818:Animals; D001835:Body Weight; D015519:Bone Density; D056970:Co-Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D059305:Diet, High-Fat / Q000009:adverse effects*; D004734:Energy Metabolism; D050155:Lipogenesis; D008066:Lipolysis; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism; D010101:Oxygen Consumption; D010641:Phenotype; D016474:Weight-Bearing
chemical_list: D056970:Co-Repressor Proteins; D009687:Nuclear Proteins; C502605:Txlng protein, mouse