Effects of leptin deficiency and short-term repletion on hepatic gene expression in genetically obese mice.

By supplying most organs of the body with metabolic substrates, the liver plays a central role in maintaining energy balance. Hepatic metabolism of glucose, fatty acids, and lipoproteins is disrupted in the leptin-deficient obese (Lep(ob)/Lep(ob)) mouse, leading to hyperglycemia, steatosis, and hypercholesterolemia. Microarray expression profiles were used to identify transcriptional perturbations that underlie the altered hepatic physiology of Lep(ob)/Lep(ob) mice. A wide variety of genes involved in fatty acid metabolism are altered in expression, which suggests that both fatty acid synthesis and oxidation programs are activated in obese mice. The expression of a small subset of genes is upregulated by leptin deficiency, not modulated by caloric restriction, and markedly suppressed by short-term leptin treatment. Among these leptin-regulated genes, apolipoprotein A-IV is a strong candidate for mediating the atherogenic-resistant phenotype of Lep(ob)/Lep(ob) mice.