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Hematopoietic tissue factor-protease-activated receptor 2 signaling promotes hepatic inflammation and contributes to pathways of gluconeogenesis and steatosis in obese mice.

ABSTRACT: Failure to inhibit hepatic gluconeogenesis is a major mechanism contributing to fasting hyperglycemia in type 2 diabetes and, along with steatosis, is the hallmark of hepatic insulin resistance. Obesity is associated with chronic inflammation in multiple tissues, and hepatic inflammation is mechanistically linked to both steatosis and hepatic insulin resistance. Here, we delineate a role for coagulation signaling via tissue factor (TF) and proteinase-activated receptor 2 (PAR2) in obesity-mediated hepatic inflammation, steatosis, and gluconeogenesis. In diet-induced obese mice, TF tail signaling independent of PAR2 drives CD11b(+)CD11c(+) hepatic macrophage recruitment, and TF-PAR2 signaling contributes to the accumulation of hepatic CD8(+) T cells. Transcripts of key pathways of gluconeogenesis, lipogenesis, and inflammatory cytokines were reduced in high-fat diet-fed mice that lack the cytoplasmic domain of TF (F3) (TF(?CT)) or that are deficient in PAR2 (F2rl1), as well as by pharmacological inhibition of TF-PAR2 signaling in diet-induced obese mice. These gluconeogenic, lipogenic, and inflammatory pathway transcripts were similarly reduced in response to genetic ablation or pharmacological inhibition of TF-PAR2 signaling in hematopoietic cells and were mechanistically associated with activation of AMP-activated protein kinase (AMPK). These findings indicate that hematopoietic TF-PAR2 signaling plays a pivotal role in the hepatic inflammatory responses, steatosis, and hepatic insulin resistance that lead to systemic insulin resistance and type 2 diabetes in obesity.

SUBMITTER: Wang J

PROVIDER: S-EPMC4305186 | biostudies-other | 2015 Feb

REPOSITORIES: biostudies-other

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Hematopoietic tissue factor-protease-activated receptor 2 signaling promotes hepatic inflammation and contributes to pathways of gluconeogenesis and steatosis in obese mice.

Wang Jing J Chakrabarty Sagarika S Bui Quyen Q Ruf Wolfram W Samad Fahumiya F

The American journal of pathology 20141202 2

Failure to inhibit hepatic gluconeogenesis is a major mechanism contributing to fasting hyperglycemia in type 2 diabetes and, along with steatosis, is the hallmark of hepatic insulin resistance. Obesity is associated with chronic inflammation in multiple tissues, and hepatic inflammation is mechanistically linked to both steatosis and hepatic insulin resistance. Here, we delineate a role for coagulation signaling via tissue factor (TF) and proteinase-activated receptor 2 (PAR2) in obesity-mediat ...[more]

PMID: 25476527

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Project description:BackgroundPeroxisome proliferator-activated receptor gamma (PPARγ) signaling has been shown to regulate lipogenesis and lipid accumulation. Previous studies have shown that hepatic PPARγ is up-regulated in steatotic liver of both animal and human. However, the effects of hepatic PPARγ signaling on alcoholic liver disease (ALD) remain elusive.MethodsTo determine the role of hepatic PPARγ signaling on ALD, wild-type (WT) and hepatocyte-specific PPARγ knockdown (PPARγ∆Hep) mice were fed a modified Lieber-DeCarli alcohol or isocaloric maltose dextrin control liquid diet for 8 weeks to induce ALD. Blood parameters, hepatic steatosis, and inflammation were measured after 8-week alcohol feeding.ResultsAlcohol feeding to WT mice resulted in liver damage (alanine aminotransferase [ALT], 94.68 ± 17.05 U/L; aspartate aminotransferase [AST], 55.87 ± 11.29 U/L), which was significantly alleviated by hepatic PPARγ knockdown (ALT, 57.36 ± 14.98 U/L; AST, 38.06 ± 3.35 U/L). Alcohol feeding led to marked lipid accumulation and up-regulation of lipogenic genes including fatty acid transport protein 1 (FATP1), acetyl-CoA carboxylase (ACC), fatty acid synthase (FASN), lipin1 (LIPIN1), diacylglycerol acyltransferase 1 (DGAT1), and diacylglycerol acyltransferase 2 (DGAT2) in the livers of WT mice. Knockdown of hepatic PPARγ significantly alleviated alcohol-induced lipid accumulation and abolished the up-regulation of FASN, DGAT1, and DGAT2. Silencing of PPARγ in FL83B cells significantly decreased ethanol (EtOH)-, linoleic acid-, and EtOH plus linoleic acid-induced lipid accumulation. Knockdown of hepatic PPARγ also significantly reduced alcohol-induced inflammatory chemokine (monocyte chemotactic protein 1 [MCP1], keratinocyte-derived chemokine [KC], interferon gamma-induced protein 10 [IP-10]) and inflammatory infiltration (lymphocyte antigen 6 complex, locus G [Ly6G], and F4/80).ConclusionsThe results suggest that hepatic PPARγ signaling contributes to alcohol-induced liver injury by promoting hepatic steatosis and inflammation.

Project description:Fatty liver hemorrhagic syndrome (FLHS) in laying hens, a nutritional metabolic disorder disease, can lead to the decline of laying rate, shortening of laying peak period and increase of mortality, which seriously constrain the sustainable development of layer industry. Until now, there is no effective strategies can prevent and control the occurrence of fatty liver hemorrhagic syndrome in laying hens. The AMP-activated protein kinase (AMPK), a major sensor of cellular energy status, acts a crucial role in regulating lipid metabolism, oxidative stress and inflammatory responses in body. However, the potential molecular mechanisms about AMP-activated protein kinase signal in controlling the occurrence of fatty liver hemorrhagic syndrome are remain unclear. In present study, we found that the phosphorylated AMP-activated protein kinase (Thr172) protein level was markedly reduced in palmitic acid plus oleic acid (PO)-induced primary chicken hepatocytes. Moreover, blocked AMP-activated protein kinase signal by AMP-activated protein kinase inhibitor compound C obviously exacerbated lipid metabolism disorders, oxidative stress and inflammatory response triggered by palmitic acid plus oleic acid in primary chicken hepatocytes. Nevertheless, the lipid metabolism disorders, oxidative stress and inflammatory response challenged by palmitic acid plus oleic acid were obviously alleviated through activation of AMP-activated protein kinase signal with AMP-activated protein kinase activator AICAR in hepatocytes. In addition, we found that the beneficial effects of AMP-activated protein kinase signal in relieving lipid metabolism disorders, oxidative stress and inflammatory response are achieved by activating the nuclear factor erythroid 2-related factor 2 (NRF-2)/kelch-like ECH-associated protein 1 (KEAP1) pathway and inhibiting the NF-κB pathway in PO-stimulated primary chicken hepatocytes. Collectively, our data demonstrated that AMP-activated protein kinase acts as a potential target for the prevention of fatty liver hemorrhagic syndrome occurrence in laying hens.

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Hematopoietic tissue factor-protease-activated receptor 2 signaling promotes hepatic inflammation and contributes to pathways of gluconeogenesis and steatosis in obese mice.

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Hematopoietic tissue factor-protease-activated receptor 2 signaling promotes hepatic inflammation and contributes to pathways of gluconeogenesis and steatosis in obese mice.

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