Background & aims: The catabolic pathways of n-3 triglyceride (TG) rich particles (n-3 TGRP) have not been clearly elucidated. In this study, we investigated the effects of lipoprotein lipase (LPL) on the catabolism of n-3 TGRP compared to n-6 TGRP in vivo and in vitro, and we determined whether particle size affects the biological functions of LPL in n-3 TGRP catabolism.Methods: Four types of lipid emulsions, chylomicron (CM)-sized n-3 TG and n-6 TG emulsions, and very low density lipoprotein (VLDL)-sized n-3 TG and n-6 TG emulsions, were labeled with 1,1'-dloctadecy1-3,3,3',3'-tetramethylindo-carbocyanine perchlorate (DiI) and administered via a bolus injection to LPL gene knockout (LPL+/-) mice in vivo and were added to cultured LPL miRNA-transfected 3T3-L1 adipocytes in vitro.Results: With CM-sized emulsions, a reduction in LPL expression in LPL+/- mice had almost no effect on tissue uptake of n-3 TG emulsions with smaller changes in their initial blood clearance; however, greater effects were observed for VLDL-sized n-3 TG emulsions with respect to tissue uptake with greater changes in their initial blood clearance, compared to n-6 TG emulsions with the same size. In vitro, LPL miRNA transfection had smaller effects on CM-sized and greater effects on VLDL-sized n-3 TG emulsions, with respect to particle uptake, cell TG mass, particle-cell binding and particle lipolysis.Conclusion: These results suggested that LPL is more important for catabolism of n-3 TGRP of smaller size; whereas it is essential for catabolism of all sizes of n-6 TGRP. (C) 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

We report evidence of a detailed epigenetic modification of the leptin promoter and the effects of n-3 polyunsaturated fatty acids (n-3 PUFAs), which is closely associated with the leptin gene transcription in obesity. In the adipose tissue of diet induced obese (DIO) mice, methylation of the CpG island and the binding of methyl-CpG-binding domain protein 2 (MBD2) and DNA methyltransferases (DNMTs) at the leptin promoter are increased and RNA Pol II is decreased. Additionally, histones H3 and H4 are hypoacetylated, lysine 4 of histone H3 (H3K4) is hypomethylated and the binding of histone deacetylases (HDACs) 1, 2 and 6 is increased at the leptin promoter in the DIO mice. These modifications may serve a feedback role to maintain leptin concentrations within a normal range. The regulation of leptin transcriptional expression by n-3 PUFAs is mediated, at least in part, by epigenetic targets, such as MBD2 and histone modifications.

OBJECTIVEThe role of epigenetic modifications on leptin expression during the development of obesity has not been clearly determined. This study aimed to investigate changes in the expression of DNA methyltransferases (DNMTs) at the leptin promoter and their effect on gene transcription during the development of obesity.METHODSUsing a high-fat diet (HFD)-induced obese (DIO) mouse model, we examined adipose expression of leptin, its promoter associated DNMTs and the methyl CpG-binding domain protein 2 (MBD2) at different time points after HFD feeding.RESULTSThe leptin expression levels in epididymal fat were significantly increased after feeding the mice a HFD for 4, 8, 12 and 18 weeks (w), as opposed to feeding them a standard diet (SD). However, the CpG promoter methylation fractions were significantly reduced at 8 w with a decreased association of MBD2 and DNMT1, and increased at 12 w and 18 w with an increased association of MBD2, DNMT3A and DNMT3B, after HFD feeding. Additionally, the binding of RNA polymerase II was increased at 8 w and decreased at 18 w after HFD feeding compared with SD feeding.CONCLUSIONSThese data indicate that time-specific changes in promoter associated DNMTs may be associated with the regulation of leptin expression, indicating that a complex and dynamic epigenetic mechanism underlies aberrant leptin expression during the development of obesity.

OBJECTIVE:To investigate the genome-wide promoter methylation and gene expression for the identification of methylation markers in obesity.METHODS:Using a high-fat, diet-induced obese mouse model, we performed comprehensive DNA methylation profiling of gene promoters to determine the differentially methylated genes using methylated DNA immunoprecipitation followed by hybridization to the NimbleGen MM8 CpG plus Promoter Microarray. We further integrated epigenomics data with gene expression profiling to identify promoters exhibiting an association between methylation status and the expression of downstream genes.RESULTS:A total of 24 hypermethylated promoters and 42 hypomethylated promoters in epididymal fat were selected as methylation markers, which were associated with downregulated and upregulated gene expression, respectively. The promoter methylation and differential gene expression of three markers (Mmp2, Foxj3 and Ube2q2) in the fat were validated by sequencing bisulfitemodified DNA and real-time reverse transcriptase PCR. The genes with these differentially methylated promoters and the associated transcriptional expression in the fat were primarily involved in biological activities in lipid metabolism and storage, cellular differentiation, immunity and the pathogenesis of obesity-related complications.CONCLUSIONS:This study represents the first effort to determine methylation markers in obese mice that may regulate gene transcription in obesity. Our approach has potential relevance for clinical applications by identifying markers useful in elucidating the mechanisms of obesity pathogenesis and its complications.

In this study, we investigated epigenetic modifications in the promoter region of the leptin gene and related effects of dietary n‐3 polyunsaturated fatty acids (n‐3 FA) in diet induced obese (DIO) mice. Male C57 BL/6J mice were fed with two high‐fat diets with different fat types – sunflower oil (n‐3 FA deficient) and fish oil, with a low‐fat diet ‐‐ sunflower oil as control. Compared to the mice fed with the control diet, expressions of leptin in plasma and epididymal fat were increased 8 fold in the n‐3 PUFA deficient DIO mice (P<0.01), and fish oil n‐3 FA in the DIO diet reversed the increased leptin expressions. The mean methylation fractions in most CpG sites of the leptin promoter were higher in the DIO mice (77% and 75%) than those in control (70%) with increasing binding of methylated CpG binding protein 2 by 40%. Also, increased H3 acetylation and decreased H4 acetylation at the leptin promoter were found in n‐3 deficient DIO mice, and the increased H3 acetylation was inhibited by dietary n‐3 FA. Methylation of Lys4 on H3 (H3K4) was reduced and that of Lys9 on H3 (H3K9) was increased in n‐3 deficient DIO mice as compared with control mice, and n‐3 FA in the DIO diet reversed the reduction of H3K4 methylation with no effects on H3K9 methylation. Therefore, epigenetic modification of the leptin promoter region may relate to expressions of leptin and this process may be regulated in part by n‐3 FA.Supported by the Nutricia Research Foundation (2009–15 and 2010‐E4).Grant Funding Source: Nutrition (ASN)

Objective: To study the relation of PC-1,EphA3 and SGEF in the protein expression in 293T and LNCaP cells.Methods: We detected the relation of EphA3,SGEF and PC-1 in LNCaP cells by RT-PCR and Western blot.The influences of EphA3 on the expression of SGEF in 293T and LNCaP cells were detected.Results: In LNCaP cells,EphA3 and SGEF can be induced by PC-1 in the level of RNA and protein,whlie EphA3 has no apparente influence on SGEF.In 293T cells,SGEF is regulated by EphA3.Conclusion: The interaction on the protein expression of PC-1,EphA3 and SGEF is associated with the types of cells.