title: Modulation of adipose tissue lipolysis and body weight by high-density lipoproteins in mice.
abstract: BACKGROUND
  Obesity is associated with reduced levels of circulating high-density lipoproteins (HDLs) and its major protein, apolipoprotein (apo) A-I. As a result of the role of HDL and apoA-I in cellular lipid transport, low HDL and apoA-I may contribute directly to establishing or maintaining the obese condition.
  
  
  METHODS
  To test this, male C57BL/6 wild-type (WT), apoA-I deficient (apoA-I(-/-)) and apoA-I transgenic (apoA-I(tg/tg)) mice were fed obesogenic diets (ODs) and monitored for several clinical parameters. We also performed cell culture studies.
  
  
  RESULTS
  ApoA-I(-/-) mice gained significantly more body weight and body fat than WT mice over 20 weeks despite their reduced food intake. During a caloric restriction regime imposed on OD-fed mice, apoA-I deficiency significantly inhibited the loss of body fat as compared with WT mice. Reduced body fat loss with caloric restriction in apoA-I(-/-) mice was associated with blunted stimulated adipose tissue lipolysis as verified by decreased levels of phosphorylated hormone-sensitive lipase (p-HSL) and lipolytic enzyme mRNA. In contrast to apoA-I(-/-) mice, apoA-I(tg/tg) mice gained relatively less weight than WT mice, consistent with other reports. ApoA-I(tg/tg) mice showed increased adipose tissue lipolysis, verified by increased levels of p-HSL and lipolytic enzyme mRNA. In cell culture studies, HDL and apoA-I specifically increased catecholamine-induced lipolysis possibly through modulating the adipocyte plasma membrane cholesterol content.
  
  
  CONCLUSIONS
  Thus, apoA-I and HDL contribute to modulating body fat content by controlling the extent of lipolysis. ApoA-I and HDL are key components of lipid metabolism in adipose tissue and constitute new therapeutic targets in obesity.
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: H
authors.initials: H
authors.lastname: Wei
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Averill
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: T S
authors.initials: TS
authors.lastname: McMillen
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: F
authors.initials: F
authors.lastname: Dastvan
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: P
authors.initials: P
authors.lastname: Mitra
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Subramanian
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Tang
authors.affiliation: Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA.
authors.forename: A
authors.initials: A
authors.lastname: Chait
authors.affiliation: 1] Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, and Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA, USA [2] Center of Cardiovascular Biology, Department of Medicine, University of Washington, Seattle, WA, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Leboeuf