Sex differences in the expression and function of hepatic very low-density lipoprotein receptor during protein deficiency in mice
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ABSTRACT: Very low-density lipoprotein (VLDL) receptor (VLDLR), a member of the low-density lipoprotein receptor family, is responsible for VLDL uptake in peripheral tissues. We reported that significant increase in hepatic VLDLR levels following protein restriction in male mice does not contribute to hepatic fat accumulation, indicating that VLDLR may have hitherto unknown functions. Here, we used RNA-sequencing analysis of liver samples to analysis the effects of protein restriction on hepatic VLDLR in male and female mice.
Project description:We previously found that a native lipoprotein mix with a high VLDL+LDL/HDL ratio causes a global de novoDNA methylation in THP-1 macrophages. In the present experiment we assessed the consequences of global lipoprotein-induced de novo DNA methylation on global gene expression in the same cells. Moreover, we sought to use gene expression array data to measure RNA expression levels for candidate factors mediating the epigenetic effects of lipoproteins. Experiment Overall Design: Human native VLDL, LDL and HDL lipoproteins were isolated from buffy coats, fractionated by ultracentrifugation, stored at -80deg., desalted to PBS before usage and kept at 4deg. for a maximum of 7d. THP-1 monocytes were differentiated to macrophages, stimulated for 24h with a mix of 68.8mg/ml VLDL, 32.1mg/ml LDL, 91.1mg/ml HDL or unstimulated (control), in serum-free medium with 2% BSA. Three independently isolated lipoprotein samples were used in triplicate.
Project description:Stearoyl-CoA desaturase 1-deficient (SCD1-/-) mice have impaired monounsaturated fatty acid (MUFA) synthesis. When maintained on a very low-fat, high-carbohydrate (VLF-HC) diet, SCD1-/- mice develop severe hypercholesterolemia characterized by an increase in apolipoprotein B-containing lipoproteins and the appearance of lipoprotein-X. Additionally, high-density lipoprotein cholesterol is dramatically reduced in VLF-HC SCD1-/- mice. The concomitant presence of elevated plasma bile acids, bilirubin and aminotransferases in the VLF-HC SCD1-/- mouse are indicative of hepatic dysfunction. Supplementation of the VLF-HC diet with unsaturated fat (canola oil), but not saturated fat (coconut oil), prevents these plasma phenotypes. However, dietary oleate was not as effective as canola oil in reducing low-density lipoprotein cholesterol, signifying an additional role for dietary polyunsaturated fatty acid deficiency in the development of this phenotype. These results indicate that lack of SCD1 results in an increased requirement for dietary unsaturated fat to compensate for impaired MUFA synthesis and to prevent hypercholesterolemia and hepatic dysfunction. Keywords: repeat (genotype and diet)
Project description:The MS data set contains the result from HDL VLDL corona used in the publication, titled Multiomics analysis of naturally efficacious LNP coronas reveals high-density lipoprotein is necessary for LNP function.
Project description:The very low density lipoprotein receptor (VLDLR) is a multi-ligand receptor that mediates pleiotropic biological processes, such as brain development. In this dataset, we include the expression data obtained from lungs from mice that had been challenged with house dust mite to induce experimental asthma or saline, as a control. These data are used to obtain genes that are differentially expressed in response to VLDLR signaling.
Project description:The very low density lipoprotein receptor (VLDLR) is a multi-ligand receptor that mediates pleiotropic biological processes, such as brain development. In this dataset, we include the expression data obtained from lungs from mice that had been challenged with house dust mite to induce experimental asthma or saline, as a control. These data are used to obtain genes that are differentially expressed in response to VLDLR signaling. We compared wild type and VLDLR knock out mice that had been sensitized and challenged with house dust mite or saline, as a control. There were total 16 samples with four biological relicates in each group.
Project description:Background and Aims: Inflammasome-mediated caspase-1 activity regulates the maturation and release of the pro-inflammatory cytokines interleukin (IL)-1M-CM-^_ and IL-18. Recently, we showed that caspase-1 deficiency strongly reduces high fat diet-induced adiposity although the mechanism is still unclear. We now aimed to elucidate the mechanism by which caspase-1 deficiency reduces modulates resistance to high fat diet-feeding fat accumulation in adipose tissue by focusing on the role of caspase-1 in the regulation of triglyceride (TG)-rich lipoprotein metabolism. Methods: Caspase-1 deficient and wild-type mice (both C57Bl/6 background) were used to determine postprandial TG kinetics, intestinal TG absorption, VLDL-TG production as well as TG clearance, all of which strongly contribute to the supply of TG for storage in adipose tissue. Micro-array and qPCR analysis were used to unravel intestinal and hepatic metabolic pathways involved. Results: Caspase-1 deficiency reduced the postprandial response to an oral lipid load, while tissue specific clearance of TG-rich lipoproteins was not changed. Indeed, an oral olive oil gavage containing [3H]TG revealed that caspase-1 deficiency significantly decreased intestinal chylomicron-TG production and reduced the uptake of [3H]TG-derived FA by liver, muscle, and adipose tissue. Similarly, caspase-1 deficiency reduced the hepatic VLDL-TG production without reducing VLDL-apoB production, despite an elevated hepatic TG content. Pathway analysis revealed that caspase-1 deficiency reduces intestinal and hepatic expression of genes involved in lipogenesis. Conclusions: Absence of caspase-1 reduces assembly and secretion of TG-rich lipoproteins, thereby reducing the availability of TG-derived FA for uptake by peripheral organs including adipose tissue. We anticipate that caspase-1 represents a novel link between innate immunity and lipid metabolism. Keywords: Expression profiling by array Wild-type (WT) and Casp1-null mice were maintained at lab chow. Animals, aged between 14 and 16 weeks (n=3 per genotype), were killed and liver and intestinal segments were removed. Livers were isolated from mice that were fasted over night, whereas intesines were removed from mice 2 hrs after they received an oral lipid load.Total RNA was isolated and subjected to gene expression profiling.
Project description:Background: Non-alcoholic fatty liver disease (NAFLD) affects nearly 25% of the global population. Cardiovascular disease (CVD) is the most common cause of death among patients with NAFLD, in line with highly prevalent dyslipidemia in this population. Increased plasma triglyceride (TG)-rich lipoprotein (TRL) concentrations, an important risk factor for CVD, are closely linked with hepatic TG content. Therefore, it is of great interest to identify regulatory mechanisms of hepatic TRL production and remnant uptake in the setting of hepatic steatosis. Approach and results: To identify liver-regulated pathways linking intra-hepatic and plasma TG metabolism, we performed transcriptomic analysis of liver biopsies from two independent cohorts of obese patients. Hepatic APOF (encoding apolipoprotein F) expression showed the 4th strongest negatively correlation with hepatic steatosis and the strongest negative correlation with plasma TG levels. The effects of adenoviral-mediated human ApoF (hApoF) overexpression on plasma and hepatic TG were assessed in C57BL6/J mice. Surprisingly, hApoF overexpression increased both hepatic VLDL-TG secretion and hepatic lipoprotein remnant clearance, associated a ~25% reduction in plasma TG levels. Conversely, reducing endogenous ApoF expression reduced VLDL secretion in vivo, and reduced hepatocyte VLDL uptake by ~15% in vitro. Transcriptomic analysis of APOF-overexpressing mouse livers revealed a gene signature related to enhanced ApoB-lipoprotein clearance, including increased expression of Ldlr and Lrp1, among others. Conclusion: These data reveal a previously undescribed role for ApoF in the control of plasma and hepatic lipoprotein metabolism by favoring VLDL-TG secretion and hepatic lipoprotein remnant particle clearance.
Project description:Background and Aims: Inflammasome-mediated caspase-1 activity regulates the maturation and release of the pro-inflammatory cytokines interleukin (IL)-1ß and IL-18. Recently, we showed that caspase-1 deficiency strongly reduces high fat diet-induced adiposity although the mechanism is still unclear. We now aimed to elucidate the mechanism by which caspase-1 deficiency reduces modulates resistance to high fat diet-feeding fat accumulation in adipose tissue by focusing on the role of caspase-1 in the regulation of triglyceride (TG)-rich lipoprotein metabolism. Methods: Caspase-1 deficient and wild-type mice (both C57Bl/6 background) were used to determine postprandial TG kinetics, intestinal TG absorption, VLDL-TG production as well as TG clearance, all of which strongly contribute to the supply of TG for storage in adipose tissue. Micro-array and qPCR analysis were used to unravel intestinal and hepatic metabolic pathways involved. Results: Caspase-1 deficiency reduced the postprandial response to an oral lipid load, while tissue specific clearance of TG-rich lipoproteins was not changed. Indeed, an oral olive oil gavage containing [3H]TG revealed that caspase-1 deficiency significantly decreased intestinal chylomicron-TG production and reduced the uptake of [3H]TG-derived FA by liver, muscle, and adipose tissue. Similarly, caspase-1 deficiency reduced the hepatic VLDL-TG production without reducing VLDL-apoB production, despite an elevated hepatic TG content. Pathway analysis revealed that caspase-1 deficiency reduces intestinal and hepatic expression of genes involved in lipogenesis. Conclusions: Absence of caspase-1 reduces assembly and secretion of TG-rich lipoproteins, thereby reducing the availability of TG-derived FA for uptake by peripheral organs including adipose tissue. We anticipate that caspase-1 represents a novel link between innate immunity and lipid metabolism. Keywords: Expression profiling by array