Browsing by Author "Henderson, Gregory C."

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    Albumin Deficiency Reduces Hepatic Steatosis and Improves Glucose Metabolism in a Mouse Model of Diet-Induced Obesity
    (MDPI, 2023-04-25) Abdollahi, Afsoun; Narayanan, Sanjeev K.; Frankovich, Alexandra; Lai, Yen-Chun; Zhang, Yi; Henderson, Gregory C.; Anatomy, Cell Biology and Physiology, School of Medicine
    Serum albumin facilitates the transport of free fatty acids (FFAs) from adipose tissue to other organs. It was not known if impeding this process could protect from hepatic steatosis and metabolic dysfunction in obesity. We tested whether albumin knockout (Alb−/−) mice would exhibit a reduction in plasma FFA concentration, reduced hepatic lipid accumulation, and improved glucoregulation as compared to wild-type (WT) mice. Male homozygous albumin knockout mice (Alb−/−) and WT controls were fed a low-fat diet (LFD) or high-fat diet (HFD). Alb−/− mice exhibited a similar body weight gain and body composition as WT on both diets. Despite HFD-induced obesity, Alb−/− mice were protected from various comorbidities. Compared to WT mice on the HFD, Alb−/− exhibited lower plasma FFA levels, lower blood glucose levels during glucose tolerance and insulin tolerance tests, and lower hepatic steatosis and inflammation. Alb−/− mice on HFD also exhibited elevated expression of multiple genes in the liver and adipose tissues, such as peroxisome proliferator-activated receptor α in both tissues, as well as glucose transporter-4 and adiponectin in adipose tissues. The results indicate that albumin’s FFA transport function may be involved in the development of hepatic lipid accumulation and dysregulated glucose metabolism in obesity.
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    GCN2 is required to increase fibroblast growth factor 21 and maintain hepatic triglyceride homeostasis during asparaginase treatment
    (APS, 2015-02-15) Wilson, Gabriel J.; Lennox, Brittany A.; She, Pengxiang; Mirek, Emily T.; Al Baghdadi, Rana J. T.; Fusakio, Michael E.; Dixon, Joseph L.; Henderson, Gregory C.; Wek, Ronald C.; Anthony, Tracy G.; Department of Biochemistry & Molecular Biology, IU School of Medicine
    The antileukemic agent asparaginase triggers the amino acid response (AAR) in the liver by activating the eukaryotic initiation factor 2 (eIF2) kinase general control nonderepressible 2 (GCN2). To explore the mechanism by which AAR induction is necessary to mitigate hepatic lipid accumulation and prevent liver dysfunction during continued asparaginase treatment, wild-type and Gcn2 null mice were injected once daily with asparaginase or phosphate buffered saline for up to 14 days. Asparaginase induced mRNA expression of multiple AAR genes and greatly increased circulating concentrations of the metabolic hormone fibroblast growth factor 21 (FGF21) independent of food intake. Loss of Gcn2 precluded mRNA expression and circulating levels of FGF21 and blocked mRNA expression of multiple genes regulating lipid synthesis and metabolism including Fas, Ppara, Pparg, Acadm, and Scd1 in both liver and white adipose tissue. Furthermore, rates of triglyceride export and protein expression of apolipoproteinB-100 were significantly reduced in the livers of Gcn2 null mice treated with asparaginase, providing a mechanistic basis for the increase in hepatic lipid content. Loss of AAR-regulated antioxidant defenses in Gcn2 null livers was signified by reduced Gpx1 gene expression alongside increased lipid peroxidation. Substantial reductions in antithrombin III hepatic expression and activity in the blood of asparaginase-treated Gcn2 null mice indicated liver dysfunction. These results suggest that the ability of the liver to adapt to prolonged asparaginase treatment is influenced by GCN2-directed regulation of FGF21 and oxidative defenses, which, when lost, corresponds with maladaptive effects on lipid metabolism and hemostasis.