- Email: [email protected]
Dietary fatty acids and formation of lipid droplets in human preadipocytes (SVF) and endothelial cells
S6
Abstracts / Chemistry and Physics of Lipids 164S (2011) S5–S8
PL 7 Dietary fatty acids and formation of lipid droplets in human preadipocytes (SVF) and endothelial cells Beata Kiec-Wilk 1,2 , Anna Dembinska-Kiec 1,∗
Polus 1 , Gerd
Schmitz 3 , Aldona
1
Department of Clinical Biochemistry, Jagiellonian University, Cracow, Poland 2 Department of Metabolic Diseases, Jagiellonian University, Cracow, Poland 3 Department of Clinical Biochemistry, University Hospital, Regensburg, Germany Insulin resistance-induced hyperglycemia and excess of circulating free fatty acids (FFA) is the hall-mark of glucolipotoxicity and lipid droplet (LD) formation in cells not devoted to metabolic substrate storage. Mitochondrial substrate overload induces free radical formation, endoplasmic reticulum (ER)-stress, changes in mitochondrial membrane potential (Dy), and LD formation. The fluctuating changes in mitochondrial membrane potential (MMP) induces autophagy promoting lysosomal degradation of modified proteins and lipids – the important mechanisms for cell survival and protection from apoptosis and cellular death. Dietary FFAs (PA, OA, except EPA) induced formation of different to SVF (TG-rich) type of LD than in endothelial cells (phospholipid-rich). The bioinformatic analysis of microarray (Agilent) and lipidomic (MS/MS) results revealed an different (in comparison with the other FA) ability of EPA to induce the ER-stress, apoptosis, angiogenesis related gene clusters. All used FFAs, activated autophagy – related genes (i.e. charperones, LAMP2) expression. Additionally AA induced the lipodystrophy gene Lpin what may explain the decreased accumulation of LD in SVF in presence of this FA. Thus EPA protects endothelial cells against the FFA-induced lipotoxicity by accelerating glucose uptake and metabolism, protects against mitochondrial impairment, ER stress and in consequences against the stress-induced LD phospholipidosis, cellular dysfunction and death. The effect of changes in sphingomyelin, ceramide and phospholipid composition (length in FFA) is noticed. Acknowledgements: This work was supported by EU F7: LIPIDOMICNET (Grant Agreement 202272). doi:10.1016/j.chemphyslip.2011.05.042 PL 8 Mechanisms behind beneficial effects of marine lipids
and hence properties of cellular membranes, gene transcription, adiponectin-mediated induction of AMP-activated protein kinase activity, cannabinoid receptors, and other mechanisms. Our experiments in C57BL/6 mice fed high-fat diet revealed that liver, white adipose tissue and muscle represent important targets for n−3 LCPUFA action. Tissue-specific effects of n−3 LC-PUFA depend in large on the combination with other treatments. Thus, combined treatment using n−3 LC-PUFA and (i) a mild calorie restriction reduced strongly body fat accumulation, while inducing a metabolic switch toward lipid catabolism and suppression of lipogenesis in adipose tissue; and (ii) antidiabetics thizolidinediones, exerted additive effects in the counteraction of obesity, dyslipidaemia and insulin resistance, while improving in additive/synergistic manner muscle insulin sensitivity. Both types of combination treatments exerted additivity in the suppression of low-grade inflammation, which is associated with obesity. These results are relevant for improving therapy for patients with diabetes and other diseases clustered in metabolic syndrome. doi:10.1016/j.chemphyslip.2011.05.043 SO 6 Controlling cholesterol synthesis beyond HMG-CoA reductase Saloni Gill, Julian Stevenson, Ika Kristiana, Andrew Brown ∗ BABS, University of New South Wales, Sydney, Australia Exquisite control of cholesterol synthesis is crucial for maintaining homeostasis of this vital yet potentially toxic lipid. Squalene monooxygenase (SM) catalyzes the first oxygenation step in cholesterol synthesis, acting on squalene before cyclization into the basic steroid structure. Using model cell systems, we found that cholesterol caused the accumulation of the substrate squalene, suggesting that SM may serve as a flux-controlling enzyme beyond 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR, considered as rate-limiting). Cholesterol accelerated the proteasomal degradation of SM which required the N-terminal domain, partially conserved in vertebrates, but not lower organisms. Unlike HMGR, SM degradation is not mediated by Insig, 24,25-dihydrolanosterol or side-chain oxysterols, but rather by cholesterol itself. Importantly, SM’s N-terminal domain conferred cholesterol-regulated turnover on heterologous fusion proteins. Furthermore, proteasomal inhibition almost totally eliminated squalene accumulation, highlighting the importance of this degradation mechanism for the control of SM, and suggesting this as a possible control point in cholesterol synthesis.
Jan Kopecky Department of Adipose Tissue Biology, Institute of Physiology of the Academy of Sciences of the Czech Republic, Prague, Czech Republic Development of obesity-associated diseases, like type 2 diabetes, dyslipidaemia and cardiovascular disease (i.e., components of metabolic syndrome) could be delayed by lifestyle modifications, while both dietary and pharmacological interventions are required for the therapy. Naturally occurring n−3 long-chain (LC) PUFA, EPA and DHA, act as hypolipidaemics, reduce cardiac events and may decrease the progression of atherosclerosis. In animal studies, n−3 LC-PUFA efficiently prevent the development of obesity, hepatic steatosis and dyslipidaemia, as well as impaired glucose tolerance, while exerting pronounced anti-inflammatory effects. However, in diabetic patients, n−3 LC-PUFA appeared to have little effect on glycaemic control. Biological effects of n−3 LC-PUFA and their active metabolites, eicosanoids and other lipid mediators, are mediated by multiple mechanisms in peripheral tissues, including the changes in fatty acid composition of phospholipids
doi:10.1016/j.chemphyslip.2011.05.044
Abstracts / Chemistry and Physics of Lipids 164S (2011) S5–S8
PL 7 Dietary fatty acids and formation of lipid droplets in human preadipocytes (SVF) and endothelial cells Beata Kiec-Wilk 1,2 , Anna Dembinska-Kiec 1,∗
Polus 1 , Gerd
Schmitz 3 , Aldona
1
Department of Clinical Biochemistry, Jagiellonian University, Cracow, Poland 2 Department of Metabolic Diseases, Jagiellonian University, Cracow, Poland 3 Department of Clinical Biochemistry, University Hospital, Regensburg, Germany Insulin resistance-induced hyperglycemia and excess of circulating free fatty acids (FFA) is the hall-mark of glucolipotoxicity and lipid droplet (LD) formation in cells not devoted to metabolic substrate storage. Mitochondrial substrate overload induces free radical formation, endoplasmic reticulum (ER)-stress, changes in mitochondrial membrane potential (Dy), and LD formation. The fluctuating changes in mitochondrial membrane potential (MMP) induces autophagy promoting lysosomal degradation of modified proteins and lipids – the important mechanisms for cell survival and protection from apoptosis and cellular death. Dietary FFAs (PA, OA, except EPA) induced formation of different to SVF (TG-rich) type of LD than in endothelial cells (phospholipid-rich). The bioinformatic analysis of microarray (Agilent) and lipidomic (MS/MS) results revealed an different (in comparison with the other FA) ability of EPA to induce the ER-stress, apoptosis, angiogenesis related gene clusters. All used FFAs, activated autophagy – related genes (i.e. charperones, LAMP2) expression. Additionally AA induced the lipodystrophy gene Lpin what may explain the decreased accumulation of LD in SVF in presence of this FA. Thus EPA protects endothelial cells against the FFA-induced lipotoxicity by accelerating glucose uptake and metabolism, protects against mitochondrial impairment, ER stress and in consequences against the stress-induced LD phospholipidosis, cellular dysfunction and death. The effect of changes in sphingomyelin, ceramide and phospholipid composition (length in FFA) is noticed. Acknowledgements: This work was supported by EU F7: LIPIDOMICNET (Grant Agreement 202272). doi:10.1016/j.chemphyslip.2011.05.042 PL 8 Mechanisms behind beneficial effects of marine lipids
and hence properties of cellular membranes, gene transcription, adiponectin-mediated induction of AMP-activated protein kinase activity, cannabinoid receptors, and other mechanisms. Our experiments in C57BL/6 mice fed high-fat diet revealed that liver, white adipose tissue and muscle represent important targets for n−3 LCPUFA action. Tissue-specific effects of n−3 LC-PUFA depend in large on the combination with other treatments. Thus, combined treatment using n−3 LC-PUFA and (i) a mild calorie restriction reduced strongly body fat accumulation, while inducing a metabolic switch toward lipid catabolism and suppression of lipogenesis in adipose tissue; and (ii) antidiabetics thizolidinediones, exerted additive effects in the counteraction of obesity, dyslipidaemia and insulin resistance, while improving in additive/synergistic manner muscle insulin sensitivity. Both types of combination treatments exerted additivity in the suppression of low-grade inflammation, which is associated with obesity. These results are relevant for improving therapy for patients with diabetes and other diseases clustered in metabolic syndrome. doi:10.1016/j.chemphyslip.2011.05.043 SO 6 Controlling cholesterol synthesis beyond HMG-CoA reductase Saloni Gill, Julian Stevenson, Ika Kristiana, Andrew Brown ∗ BABS, University of New South Wales, Sydney, Australia Exquisite control of cholesterol synthesis is crucial for maintaining homeostasis of this vital yet potentially toxic lipid. Squalene monooxygenase (SM) catalyzes the first oxygenation step in cholesterol synthesis, acting on squalene before cyclization into the basic steroid structure. Using model cell systems, we found that cholesterol caused the accumulation of the substrate squalene, suggesting that SM may serve as a flux-controlling enzyme beyond 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR, considered as rate-limiting). Cholesterol accelerated the proteasomal degradation of SM which required the N-terminal domain, partially conserved in vertebrates, but not lower organisms. Unlike HMGR, SM degradation is not mediated by Insig, 24,25-dihydrolanosterol or side-chain oxysterols, but rather by cholesterol itself. Importantly, SM’s N-terminal domain conferred cholesterol-regulated turnover on heterologous fusion proteins. Furthermore, proteasomal inhibition almost totally eliminated squalene accumulation, highlighting the importance of this degradation mechanism for the control of SM, and suggesting this as a possible control point in cholesterol synthesis.
Jan Kopecky Department of Adipose Tissue Biology, Institute of Physiology of the Academy of Sciences of the Czech Republic, Prague, Czech Republic Development of obesity-associated diseases, like type 2 diabetes, dyslipidaemia and cardiovascular disease (i.e., components of metabolic syndrome) could be delayed by lifestyle modifications, while both dietary and pharmacological interventions are required for the therapy. Naturally occurring n−3 long-chain (LC) PUFA, EPA and DHA, act as hypolipidaemics, reduce cardiac events and may decrease the progression of atherosclerosis. In animal studies, n−3 LC-PUFA efficiently prevent the development of obesity, hepatic steatosis and dyslipidaemia, as well as impaired glucose tolerance, while exerting pronounced anti-inflammatory effects. However, in diabetic patients, n−3 LC-PUFA appeared to have little effect on glycaemic control. Biological effects of n−3 LC-PUFA and their active metabolites, eicosanoids and other lipid mediators, are mediated by multiple mechanisms in peripheral tissues, including the changes in fatty acid composition of phospholipids
doi:10.1016/j.chemphyslip.2011.05.044