Transgenic mice expressing high levels of human apolipoprotein B develop severe atherosclerotic lesions in response to a high-fat diet.

Abstract Background IκBNS is one of the nuclear IκB proteins and regulates a subset of Toll-like receptor (TLR) dependent genes. LPS acts as extremely strong stimulator of innate immunity. We tried to investigate whether stimulation of innate immunity could promote atherosclerosis in the IκBNS-deficient atherogenic mice. However all IκBNS-deficient mice died of LPS challenge at a dose of which almost all wild-type mice survived, because IκBNS-deficient mice are highly sensitive to LPS-induced endotoxin shock. Then, we decided to use a cholate-containing high fat diet (HFD(CA(+))), which has been widely used as an atherogenic diet in mice. Furthermore, HFD(CA(+)) has been shown to induce TLR4 mediated early inflammatory response. The present study aims to clarify the lack of IκBNS promotes atherogenesis in LDL receptor-deficient (LDLr−/−) mice fed HFD(CA(+)) compared with those fed a cholate-free HFD (HFD(CA(−)). Methods and results Mice that lacked IκBNS (IκBNS−/−) were crossed with LDLr−/− mice and formation of atherosclerotic lesions was analyzed after 6 weeks consumption of HFD(CA(+)) or HFD(CA(−)). The extent of atherosclerosis in the aorta (en face) was significantly increased in IκBNS−/−/LDLr−/−(CA(+)) mice compared with others after 6-week consumption of HFD (p<0.01) (Figure). Interestingly, HFD(CA(−)) did not induce significant atherosclerotic lesions in IκBNS−/−/LDLr−/− compared with LDLr−/− mice after 6-week consumption (Figure). Immunostaining of aortic root lesion revealed that HFD(CA(+)) significantly increased positive area of Mac-3 (macrophage) by 1.5-fold (p=0.01) and TLR4, interleukin-6 (IL-6) expression by 1.7-fold (P<0.05) and 1.5-fold (p<0.05) respectively in IκBNS−/−/LDLr−/− (CA(+)) compared to LDLr−/− (CA(+)) mice. Furthermore, active STAT3 (pSTAT3)-positive cells were significantly increased by 1.7-fold in the atherosclerotic lesions of IκBNS−/−/LDLr−/− (CA(+)) compared with LDLr−/− (CA(+)) mice (p<0.01). TLR4 positive areas, IL-6 positive areas, and pSTAT3 positive cells were overlapped with Mac-3, indicating that TLR4-IL-6-STAT3 axis was activated in macrophages in IκBNS−/−/LDLr−/− (CA(+)) mice. On the other hand, HFD(CA(−)) could not induce any difference in these immunoreactivities of arteriosclerotic lesions between IκBNS−/−/LDLr−/− (CA(−)) compared with LDLr−/− (CA(−)) mice. These findings suggest that IκBNS deficiency and HFD(CA(+)) promote atherogenesis in LDLr−/− mice via TLR4/IL-6/STAT3 pathway. Finally, we show the monocytes from peripheral blood of IκBNS−/−/LDLr−/− (CA(+)) mice were found to contain the most mounts of Ly6Chi among four groups, suggesting that lack of IκBNS enhances inflammation in the response HFD(CA(+)) feeding and thereby influence atherogenesis in IκBNS−/−/LDLr−/− mice. Aortic root atherosclerotic lesions Conclusions The present study is the first to demonstrate that the activation of innate immune system using HFD(CA(+)) induced significant inflammation and atherogenesis in IκBNS−/−/LDLr−/− compared with LDLr−/− mice.

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SIM1 Overexpression Partially Rescues Agouti Yellow and Diet-Induced Obesity by Normalizing Food Intake

Endocrinology ◽

10.1210/en.2006-0453 ◽

2006 ◽

Vol 147 (10) ◽

pp. 4542-4549 ◽

Cited By ~ 54

Author(s):

Bassil M. Kublaoui ◽

J. Lloyd Holder ◽

Kristen P. Tolson ◽

Terry Gemelli ◽

Andrew R. Zinn

Keyword(s):

Food Intake ◽

Energy Expenditure ◽

Transgenic Mice ◽

High Fat Diet ◽

Chow Diet ◽

High Fat ◽

Enhanced Sensitivity ◽

Diet Induced Obesity ◽

Melanocortin 4 Receptor ◽

Obesity In Mice

Single-minded 1 (SIM1) mutations are associated with obesity in mice and humans. Haploinsufficiency of mouse Sim1 causes hyperphagic obesity with increased linear growth and enhanced sensitivity to a high-fat diet, a phenotype similar to that of agouti yellow and melanocortin 4 receptor knockout mice. To investigate the effects of increased Sim1 dosage, we generated transgenic mice that overexpress human SIM1 and examined their phenotype. Compared with wild-type mice, SIM1 transgenic mice had no obvious phenotype on a low-fat chow diet but were resistant to diet-induced obesity on a high-fat diet due to reduced food intake with no change in energy expenditure. The SIM1 transgene also completely rescued the hyperphagia and partially rescued the obesity of agouti yellow mice, in which melanocortin signaling is abrogated. Our results indicate that the melanocortin 4 receptor signals through Sim1 or its transcriptional targets in controlling food intake but not energy expenditure.

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CTRP9 transgenic mice are protected from diet-induced obesity and metabolic dysfunction

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00110.2013 ◽

2013 ◽

Vol 305 (5) ◽

pp. R522-R533 ◽

Cited By ~ 70

Author(s):

Jonathan M. Peterson ◽

Zhikui Wei ◽

Marcus M. Seldin ◽

Mardi S. Byerly ◽

Susan Aja ◽

...

Keyword(s):

Skeletal Muscle ◽

Adipose Tissue ◽

Transgenic Mice ◽

High Fat Diet ◽

Fat Oxidation ◽

Acid Oxidation ◽

Ampk Activation ◽

High Fat ◽

Diet Induced Obesity

CTRP9 is a secreted multimeric protein of the C1q family and the closest paralog of the insulin-sensitizing adipokine, adiponectin. The metabolic function of this adipose tissue-derived plasma protein remains largely unknown. Here, we show that the circulating levels of CTRP9 are downregulated in diet-induced obese mice and upregulated upon refeeding. Overexpressing CTRP9 resulted in lean mice that dramatically resisted weight gain induced by a high-fat diet, largely through decreased food intake and increased basal metabolism. Enhanced fat oxidation in CTRP9 transgenic mice resulted from increases in skeletal muscle mitochondrial content, expression of enzymes involved in fatty acid oxidation (LCAD and MCAD), and chronic AMPK activation. Hepatic and skeletal muscle triglyceride levels were substantially decreased in transgenic mice. Consequently, CTRP9 transgenic mice had a greatly improved metabolic profile with markedly reduced fasting insulin and glucose levels. The high-fat diet-induced obesity, insulin resistance, and hepatic steatosis observed in wild-type mice were prevented in transgenic mice. Consistent with the in vivo data, recombinant protein significantly enhanced fat oxidation in L6 myotubes via AMPK activation and reduced lipid accumulation in H4IIE hepatocytes. Collectively, these data establish CTRP9 as a novel metabolic regulator and a new component of the metabolic network that links adipose tissue to lipid metabolism in skeletal muscle and liver.

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