Apolipoprotein CIII overexpression exacerbates diet-induced obesity due to adipose tissue higher exogenous lipid uptake
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RESEARCH
Open Access
Apolipoprotein CIII overexpression exacerbates diet-induced obesity due to adipose tissue higher exogenous lipid uptake and retention and lower lipolysis rates Helena F. Raposo1, Adriene A. Paiva1, Larissa S. Kato1 and Helena C. F. de Oliveira1,2*
Abstract Background: Hypertriglyceridemia is a common type of dyslipidemia found in obesity. However, it is not established whether primary hyperlipidemia can predispose to obesity. Evidences have suggested that proteins primarily related to plasma lipoprotein transport, such as apolipoprotein (apo) CIII and E, may significantly affect the process of body fat accumulation. We have previously observed an increased adiposity in response to a high fat diet (HFD) in mice overexpressing apoCIII. Here, we examined the potential mechanisms involved in this exacerbated response of apoCIII mice to the HFD. Methods: We measured body energy balance, tissue capacity to store exogenous lipids, lipogenesis and lipolysis rates in non-transgenic and apoCIII overexpressing mice fed a HFD during two months. Results: Food intake, fat excretion and whole body CO2 production were similar in both groups. However, the adipose tissue mass (45 %) and leptin plasma levels (2-fold) were significantly greater in apoCIII mice. Lipogenesis rates were similar, while exogenous lipid retention was increased in perigonadal (2-fold) and brown adipose tissues (40 %) of apoCIII mice. In addition, adipocyte basal lipolysis (55 %) and in vivo lipolysis index (30 %) were significantly decreased in apoCIII mice. A fat tolerance test evidenced delayed plasma triglyceride clearance and greater transient availability of non-esterified fatty acids (NEFA) during the post-prandial state in the apoCIII mice plasma. Thus, apoCIII overexpression resulted in increased NEFA availability to adipose uptake and decreased adipocyte lipolysis, favoring lipid enlargement of adipose depots. Conclusion: We propose that plasma apoCIII levels represent a new risk factor for diet-induced obesity. Keywords: Adipose tissue, Hypertriglyceridemia, High-fat diet, Lipid metabolism, Transgenic animal models
Background Obesity is a condition in which excess body fat accumulates and may adversely affect one’s health. Body fat content is determined by interactions between genetic and environmental factors acting through the mediators of energy intake and expenditure [1, 2]. The World Health * Correspondence: [email protected] 1 Department of Structural and Functional Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil 2 Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato, 255, Campinas, SP CEP 13083-862, Brazil
Organization estimates that in 2014 approximately 2 billion people around the world were overweight, and approximately 600 million were obese [3]. Overweight and obesity are associated with an excess of cardiovascular and non-cardiovascular deaths in the general population [4, 5]. Hypertriglyceridemia is one of the most common types of dyslipidemia found in
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