Furthermore, unlike db/db mice with a global loss of leptin signaling, lean mice with a liver-specific loss of leptin signaling have normal total fasting plasma triglycerides and cholesterol levels.13 It appears that although mice with a hepatocyte-specific loss of leptin signaling have increased incorporation ABT-888 molecular weight of triglycerides into VLDL particles, they do not develop hypertriglyceridemia due to their concurrent reduction in hepatic apoB production. However, in more metabolically stressed obese, hyperinsulinemic mice, we did observe a more pronounced perturbation in fasting plasma triglycerides and lipid
tolerance. Interestingly, patients with metabolic syndrome have a higher proportion of large
VLDL than healthy patients, even in patients with normal plasma triglyceride levels.33 Therefore, subtle effects of hepatic leptin resistance on lipid metabolism could have a major impact on health. Our model of hepatic leptin resistance shows that loss of leptin signaling in the liver can contribute to the development of hepatic steatosis and large, triglyceride-rich lipoproteins. Given that obese humans are leptin-resistant, our data suggest that defects in lipid metabolism seen in obesity may stem in part from resistance to leptin action in the liver. Although the effects of liver leptin signaling on lipid metabolism appear subtle, our data show
that these effects are more pronounced in obese and hyperinsulinemic states. Intriguingly, polymorphisms check details in the LEPR,34 HL,35 and LPL36 genes have been linked with familial combined hyperlipidemia, the most common genetically linked hyperlipidemia in humans. Thus, alterations to HL and LPL activity in the liver due to hepatic leptin resistance may result in increased risk of dyslipidemia and perhaps contribute to the development of metabolic syndrome. We thank Streamson C. Chua (Albert Einstein College of Medicine) for his generous contribution of the Leprflox/flox mice and A. F. Parlow (National Hormone and Peptide Program) 上海皓元 for providing mouse recombinant leptin. We also thank Martin G. Myers (University of Michigan) and Christopher J. Rhodes (University of Chicago) for providing the Ad-Lepr-b virus. Additional Supporting Information may be found in the online version of this article. “
“Random integration of hepatitis B virus (HBV) DNA into the host genome is frequent in human hepatocellular carcinoma (HCC) and this leads to truncation of the HBV DNA, particularly at the C-terminal end of the HBV X protein (HBx). In this study, we investigated the frequency of this natural C-terminal truncation of HBx in human HCCs and its functional significance. In 50 HBV-positive patients with HCC, full-length HBx was detected in all nontumorous livers.