MitoNEET (mNT) (CDGSH iron-sulfur domain-containing protein 1 or CISD1) is an outer mitochondrial membrane protein that donates 2Fe-2S clusters to apo-acceptor proteins. In the present study, using a global mNT knock-out (mNTKO) mouse model, we investigated the in vivo functional role of mNT in the development of alcoholic steatohepatitis. Experimental alcoholic steatohepatitis was achieved by pair feeding wild-type (WT) and mNTKO mice with Lieber-DeCarli ethanol-containing diets for 4 weeks. Strikingly, chronically ethanol-fed mNTKO mice were completely resistant to ethanolinduced steatohepatitis as revealed by dramatically reduced hepatic triglycerides, decreased hepatic cholesterol level, diminished liver inflammatory response, and normalized serum ALT levels. Mechanistic studies demonstrated that ethanol administration to mNTKO mice induced two pivotal endocrine hormones, namely, adipose-derived adiponectin and gut-derived fibroblast growth factor 15 (Fgf15). The elevation in circulating levels of adiponectin and Fgf15 led to normalized hepatic and serum levels of bile acids, limited hepatic accumulation of toxic bile, attenuated inflammation, and amelioration of liver injury in the ethanol-fed mNTKO mice. Other potential mechanisms such as reduced oxidative stress, activated Sirt1 signaling, and diminished NF-B activity also contribute to hepatic improvement in the ethanol-fed mNTKO mice. In conclusion, the present study identified adiponectin and Fgf15 as pivotal adipose-gut-liver metabolic coordinators in mediating the protective action of mNT deficiency against development of alcoholic steatohepatitis in mice. Our findings may help to establish mNT as a novel therapeutic target and pharmacological inhibition of mNT may be beneficial for the prevention and treatment of human alcoholic steatohepatitis.NEET proteins (mitoNEET (CISD1, mNT), 3 nutrient-deprivation autophagy factor-1 (NAF-1; CISD2), and Miner 2 (CISD3)) are a class of redox active iron-sulfur (2Fe-2S) proteins (1, 2). Among the three NEET family members, mNT encoded by the CISD1 gene is the founding member of the NEET family, and it is localized in the outer mitochondrial membrane and regulates the maturation and shuttling of 2Fe-2S clusters. mNT has been identified as a mitochondrial target of the anti-diabetic thiazolidinedione drugs (3, 4). Thiazolidinediones such as pioglitazone are capable of binding and stabilizing the mNT protein against 2Fe-2S cluster release, and thus, protecting tissue from mitochondrial injury (4). NAF-1 encoded by CISD2 is closely related to mNT, sharing 44% overall sequence identity and highly similar structure and functions (1, 5). However, the functions of CISD3 are not well understood.Increasing evidences have revealed that mNT is an important regulator of diverse biological processes, including mitochondrial function, iron metabolism, reactive oxygen species (ROS) homeostasis, lipid metabolism, inflammation process, and autophagy (1-4, 6 -15). Utilizing gain and loss of function mouse models, studies have demo...

We have previously shown that the ethanol-mediated elevation of lipocaline-2 (LCN2) is closely associated with the development of alcoholic fatty liver disease (AFLD) in mice. Herein, we aimed to understand the functional significance of LCN2 induction by ethanol and to explore its underlying mechanisms. We evaluated the effects of LCN2 in an in vitro cellular alcoholic steatosis model and in an animal study using wild-type and LCN2 knockout mice fed for 4 weeks with an ethanol-supplemented Lieber-DeCarli diet. In the cellular model of alcoholic steatosis, recombinant LCN2 or overexpression of LCN2 exacerbated ethanol-induced fat accumulation, whereas knocking down LCN2 prevented steatosis in hepatocytes exposed to ethanol. Consistently, removal of LCN2 partially but significantly alleviated alcoholic fatty liver injury in mice. Mechanistically, LCN2 mediates detrimental effects of ethanol in the liver via disrupted multiple signaling pathways, including aberrant nicotinamide phosphoribosyltransferaseesirtuin 1 axis, perturbed endocrine metabolic regulatory fibroblast growth factor 15/19 signaling, and impaired chaperone-mediated autophagy. Finally, compared with healthy human livers, liver samples from patients with AFLD had lower gene expression of several LCN2-regualted molecules. Our study demonstrated a pivotal and causal role of LCN2 in the development of AFLD and suggested that targeting the LCN2 could be of great value for the treatment of human AFLD. (Am J Pathol 2016 http://dx

Lipin-1 is a phosphatidate phosphohydrolase (PAP) required for the generation of diacylglycerol during glycerolipid synthesis, and exhibits dual functions in the regulation of lipid metabolism. Lipin-1 has been implicated in the pathogenesis of alcoholic liver disease (ALD). In the present study, we assessed lipin-1 function in myeloid cells in ALD using a myeloid cell-specific lipin-1 knockout (mLipin-1KO) mouse model. Utilizing the Gao-binge ethanol feeding protocol, matched mLipin-1KO mice and littermate loxP control (WT) mice were pair-fed with either an ethanol-containing diet or an ethanol-free diet (control). Surprisingly, deletion of lipin-1 in myeloid cells dramatically attenuated liver inflammatory responses and ameliorated liver injury that would normally occur following the ethanol feeding protocol, but slightly exacerbated the ethanol-induced steatosis in mice. Mechanistically, myeloid cell-specific lipin-1 deficiency concomitantly increased the fat-derived adiponectin and ileum-derived fibroblast growth factor (FGF) 15. In concordance with concerted elevation of circulating adiponectin and FGF15, myeloid cell-specific lipin-1 deficiency diminished hepatic nuclear factor kappa B (NF-κB) activity, limited liver inflammatory responses, normalized serum levels of bile acids, and protected mice from liver damage after ethanol challenge. Our novel data demonstrate that myeloid cell-specific deletion of lipin-1 ameliorated inflammation and alcoholic hepatitis in mice via activation of endocrine adiponectin-FGF15 signaling.

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Lipin‐1 is a Mg 2+ ‐dependent phosphatidic acid phosphohydrolase involved in the generation of diacylglycerol during synthesis of phospholipids and triglycerides. Ethanol‐mediated inhibitory effects on adipose‐specific lipin‐1 expression were associated with experimental steatohepatitis in rodents. In the present study, using an adipose‐specific lipin‐1 overexpression transgenic ( Lpin1 ‐Tg) mouse model, we tested a hypothesis that adipose‐specific lipin‐1 overexpression in mice might dampen ethanol‐induced liver damage. Experimental alcoholic steatohepatitis was induced by pair‐feeding ethanol to Lpin1 ‐Tg and wild‐type (WT) mice using the chronic‐plus‐binge ethanol feeding protocol. Unexpectedly, following the chronic‐plus‐binge ethanol challenge, Lpin1 ‐Tg mice exhibited much more pronounced steatosis, exacerbated inflammation, augmented elevation of serum liver enzymes, hepatobiliary damage, and fibrogenic responses compared with the WT mice. Mechanistically, overexpression of adipose lipin‐1 in mice facilitated the onset of hepatic ferroptosis, which is an iron‐dependent form of cell death, and subsequently induced ferroptotic liver damage in mice under ethanol exposure. Concurrently, adipose lipin‐1 overexpression induced defective adiponectin signaling pathways in ethanol‐fed mice. Conclusion : We identified ferroptosis as a mechanism in mediating the detrimental effects of adipose‐specific lipin‐1 overexpression in mice under chronic‐plus‐binge ethanol exposure. Our present study sheds light on potential therapeutic approaches for the prevention and treatment of human alcoholic steatohepatitis.