Ethanol administration only slightly induced oxidative stress in WT mice, as demonstrated by the levels of hepatic malondialdehyde (MDA) (Fig. 3C). Hepatic lipin-1 ablation led to a robust increase in the hepatic MDA levels up to nearly 8-fold in mice fed a control diet compared to WT controls (Fig. 3C). Remarkably, ethanol feeding to lipin-1LKO drastically increased MDA levels ∼16-fold compared with ethanol-fed WT mice, and ∼2-fold compared with lipin-1LKO fed with control diet (Fig. 3C). The data demonstrate that removal of lipin-1 generates
oxidative stress in the liver, and the oxidative stress is further augmented in response to ethanol administration in lipin-1LKO mice. We dissected the mechanism for lipin-1 function in mediating
hepatic inflammatory process by investigating two major inflammatory regulators, NF-κB and NFATc4.[22, 23] Ethanol feeding to WT mice or deletion of hepatic lipin-1 stimulated NF-κB activity, demonstrated Metformin by increased acetylated NF-κB, enhanced phosphorylated IκBα, reduced IκBα protein, and elevated NF-κB DNA binding activity compared to WT control mice (Fig. 4). The activation of NF-κB was significantly augmented in the livers of ethanol-fed ITF2357 datasheet lipin-1LKO mice compared to all other groups (Fig. 4). Ethanol feeding significantly increased nuclear accumulation of NFATc4 and decreased the amount of NFATc4 in the cytoplasm in WT mice, and the increased nucleocytoplasmic shuttling of NFATc4 was more pronounced in ethanol-fed selleck inhibitor lipin-1LKO mice (Fig. 4).[23, 24] Collectively, these results clearly suggest that deletion of lipin-1 led to activation of both NF-κB and NFATc4 and subsequently exacerbated inflammation in ethanol-fed lipin-1LKO mice. We assessed the total hepatic fatty acid β-oxidation capacity and VLDL-TAG secretion in WT and Lipin-1LKO mice fed ethanol. The rate of hepatic fatty acid oxidation was significantly decreased in the lipin-1LKO mice fed with ethanol compared to all other groups (Fig. 5A). Accordingly, ethanol feeding
modestly but significantly reduced serum β-hydroxybutyrate (β-OHB), a marker for hepatic fatty acid oxidation, in lipin-1LKO mice compared with ethanol-fed WT mice (Fig. 5B). Ethanol administration significantly decreased the rates of VLDL-TAG secretion in the livers of WT mice compared with WT controls (Fig. 5C). VLDL-TAG secretion rates were significantly increased in lipin-1LKO mice fed a control diet compared with WT controls. Interestingly, ethanol feeding largely abolished the increase in VLDL-TAG secretion in lipin-1LKO mice (Fig. 5C). Taken together, our results demonstrate that genetic removal of hepatic lipin-1 deranges the overall rate of fatty acid oxidation and VLDL-TAG secretion, and these impairments are further aggravated in response to ethanol administration in lipin-1LKO mice. We investigated the effect of chronic alcohol administration and lipin-1 deficiency on PGC-1α.